/*
 * Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
 */

#include <linux/time.h>
#include <linux/fs.h>
#include "reiserfs.h"
#include "acl.h"
#include "xattr.h"
#include <linux/exportfs.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <asm/unaligned.h>
#include <linux/buffer_head.h>
#include <linux/mpage.h>
#include <linux/writeback.h>
#include <linux/quotaops.h>
#include <linux/swap.h>
#include <linux/uio.h>
#include <linux/bio.h>

int reiserfs_commit_write(struct file *f, struct page *page,
                          unsigned from, unsigned to);

void reiserfs_evict_inode(struct inode *inode)
{
        /*
         * We need blocks for transaction + (user+group) quota
         * update (possibly delete)
         */
        int jbegin_count =
            JOURNAL_PER_BALANCE_CNT * 2 +
            2 * REISERFS_QUOTA_INIT_BLOCKS(inode->i_sb);
        struct reiserfs_transaction_handle th;
        int err;

        if (!inode->i_nlink && !is_bad_inode(inode))
                dquot_initialize(inode);

        truncate_inode_pages_final(&inode->i_data);
        if (inode->i_nlink)
                goto no_delete;

        /*
         * The = 0 happens when we abort creating a new inode
         * for some reason like lack of space..
         * also handles bad_inode case
         */
        if (!(inode->i_state & I_NEW) && INODE_PKEY(inode)->k_objectid != 0) {

                reiserfs_delete_xattrs(inode);

                reiserfs_write_lock(inode->i_sb);

                if (journal_begin(&th, inode->i_sb, jbegin_count))
                        goto out;
                reiserfs_update_inode_transaction(inode);

                reiserfs_discard_prealloc(&th, inode);

                err = reiserfs_delete_object(&th, inode);

                /*
                 * Do quota update inside a transaction for journaled quotas.
                 * We must do that after delete_object so that quota updates
                 * go into the same transaction as stat data deletion
                 */
                if (!err) {
                        int depth = reiserfs_write_unlock_nested(inode->i_sb);
                        dquot_free_inode(inode);
                        reiserfs_write_lock_nested(inode->i_sb, depth);
                }

                if (journal_end(&th))
                        goto out;

                /*
                 * check return value from reiserfs_delete_object after
                 * ending the transaction
                 */
                if (err)
                    goto out;

                /*
                 * all items of file are deleted, so we can remove
                 * "save" link
                 * we can't do anything about an error here
                 */
                remove_save_link(inode, 0 /* not truncate */);
out:
                reiserfs_write_unlock(inode->i_sb);
        } else {
                /* no object items are in the tree */
                ;
        }

        /* note this must go after the journal_end to prevent deadlock */
        clear_inode(inode);

        dquot_drop(inode);
        inode->i_blocks = 0;
        return;

no_delete:
        clear_inode(inode);
        dquot_drop(inode);
}

static void _make_cpu_key(struct cpu_key *key, int version, __u32 dirid,
                          __u32 objectid, loff_t offset, int type, int length)
{
        key->version = version;

        key->on_disk_key.k_dir_id = dirid;
        key->on_disk_key.k_objectid = objectid;
        set_cpu_key_k_offset(key, offset);
        set_cpu_key_k_type(key, type);
        key->key_length = length;
}

/*
 * take base of inode_key (it comes from inode always) (dirid, objectid)
 * and version from an inode, set offset and type of key
 */
void make_cpu_key(struct cpu_key *key, struct inode *inode, loff_t offset,
                  int type, int length)
{
        _make_cpu_key(key, get_inode_item_key_version(inode),
                      le32_to_cpu(INODE_PKEY(inode)->k_dir_id),
                      le32_to_cpu(INODE_PKEY(inode)->k_objectid), offset, type,
                      length);
}

/* when key is 0, do not set version and short key */
inline void make_le_item_head(struct item_head *ih, const struct cpu_key *key,
                              int version,
                              loff_t offset, int type, int length,
                              int entry_count /*or ih_free_space */ )
{
        if (key) {
                ih->ih_key.k_dir_id = cpu_to_le32(key->on_disk_key.k_dir_id);
                ih->ih_key.k_objectid =
                    cpu_to_le32(key->on_disk_key.k_objectid);
        }
        put_ih_version(ih, version);
        set_le_ih_k_offset(ih, offset);
        set_le_ih_k_type(ih, type);
        put_ih_item_len(ih, length);
        /*    set_ih_free_space (ih, 0); */
        /*
         * for directory items it is entry count, for directs and stat
         * datas - 0xffff, for indirects - 0
         */
        put_ih_entry_count(ih, entry_count);
}

/*
 * FIXME: we might cache recently accessed indirect item
 * Ugh.  Not too eager for that....
 * I cut the code until such time as I see a convincing argument (benchmark).
 * I don't want a bloated inode struct..., and I don't like code complexity....
 */

/*
 * cutting the code is fine, since it really isn't in use yet and is easy
 * to add back in.  But, Vladimir has a really good idea here.  Think
 * about what happens for reading a file.  For each page,
 * The VFS layer calls reiserfs_readpage, who searches the tree to find
 * an indirect item.  This indirect item has X number of pointers, where
 * X is a big number if we've done the block allocation right.  But,
 * we only use one or two of these pointers during each call to readpage,
 * needlessly researching again later on.
 *
 * The size of the cache could be dynamic based on the size of the file.
 *
 * I'd also like to see us cache the location the stat data item, since
 * we are needlessly researching for that frequently.
 *
 * --chris
 */

/*
 * If this page has a file tail in it, and
 * it was read in by get_block_create_0, the page data is valid,
 * but tail is still sitting in a direct item, and we can't write to
 * it.  So, look through this page, and check all the mapped buffers
 * to make sure they have valid block numbers.  Any that don't need
 * to be unmapped, so that __block_write_begin will correctly call
 * reiserfs_get_block to convert the tail into an unformatted node
 */
static inline void fix_tail_page_for_writing(struct page *page)
{
        struct buffer_head *head, *next, *bh;

        if (page && page_has_buffers(page)) {
                head = page_buffers(page);
                bh = head;
                do {
                        next = bh->b_this_page;
                        if (buffer_mapped(bh) && bh->b_blocknr == 0) {
                                reiserfs_unmap_buffer(bh);
                        }
                        bh = next;
                } while (bh != head);
        }
}

/*
 * reiserfs_get_block does not need to allocate a block only if it has been
 * done already or non-hole position has been found in the indirect item
 */
static inline int allocation_needed(int retval, b_blocknr_t allocated,
                                    struct item_head *ih,
                                    __le32 * item, int pos_in_item)
{
        if (allocated)
                return 0;
        if (retval == POSITION_FOUND && is_indirect_le_ih(ih) &&
            get_block_num(item, pos_in_item))
                return 0;
        return 1;
}

static inline int indirect_item_found(int retval, struct item_head *ih)
{
        return (retval == POSITION_FOUND) && is_indirect_le_ih(ih);
}

static inline void set_block_dev_mapped(struct buffer_head *bh,
                                        b_blocknr_t block, struct inode *inode)
{
        map_bh(bh, inode->i_sb, block);
}

/*
 * files which were created in the earlier version can not be longer,
 * than 2 gb
 */
static int file_capable(struct inode *inode, sector_t block)
{
        /* it is new file. */
        if (get_inode_item_key_version(inode) != KEY_FORMAT_3_5 ||
            /* old file, but 'block' is inside of 2gb */
            block < (1 << (31 - inode->i_sb->s_blocksize_bits)))
                return 1;

        return 0;
}

static int restart_transaction(struct reiserfs_transaction_handle *th,
                               struct inode *inode, struct treepath *path)
{
        struct super_block *s = th->t_super;
        int err;

        BUG_ON(!th->t_trans_id);
        BUG_ON(!th->t_refcount);

        pathrelse(path);

        /* we cannot restart while nested */
        if (th->t_refcount > 1) {
                return 0;
        }
        reiserfs_update_sd(th, inode);
        err = journal_end(th);
        if (!err) {
                err = journal_begin(th, s, JOURNAL_PER_BALANCE_CNT * 6);
                if (!err)
                        reiserfs_update_inode_transaction(inode);
        }
        return err;
}

/*
 * it is called by get_block when create == 0. Returns block number
 * for 'block'-th logical block of file. When it hits direct item it
 * returns 0 (being called from bmap) or read direct item into piece
 * of page (bh_result)
 * Please improve the english/clarity in the comment above, as it is
 * hard to understand.
 */
static int _get_block_create_0(struct inode *inode, sector_t block,
                               struct buffer_head *bh_result, int args)
{
        INITIALIZE_PATH(path);
        struct cpu_key key;
        struct buffer_head *bh;
        struct item_head *ih, tmp_ih;
        b_blocknr_t blocknr;
        char *p = NULL;
        int chars;
        int ret;
        int result;
        int done = 0;
        unsigned long offset;

        /* prepare the key to look for the 'block'-th block of file */
        make_cpu_key(&key, inode,
                     (loff_t) block * inode->i_sb->s_blocksize + 1, TYPE_ANY,
                     3);

        result = search_for_position_by_key(inode->i_sb, &key, &path);
        if (result != POSITION_FOUND) {
                pathrelse(&path);
                if (p)
                        kunmap(bh_result->b_page);
                if (result == IO_ERROR)
                        return -EIO;
                /*
                 * We do not return -ENOENT if there is a hole but page is
                 * uptodate, because it means that there is some MMAPED data
                 * associated with it that is yet to be written to disk.
                 */
                if ((args & GET_BLOCK_NO_HOLE)
                    && !PageUptodate(bh_result->b_page)) {
                        return -ENOENT;
                }
                return 0;
        }

        bh = get_last_bh(&path);
        ih = tp_item_head(&path);
        if (is_indirect_le_ih(ih)) {
                __le32 *ind_item = (__le32 *) ih_item_body(bh, ih);

                /*
                 * FIXME: here we could cache indirect item or part of it in
                 * the inode to avoid search_by_key in case of subsequent
                 * access to file
                 */
                blocknr = get_block_num(ind_item, path.pos_in_item);
                ret = 0;
                if (blocknr) {
                        map_bh(bh_result, inode->i_sb, blocknr);
                        if (path.pos_in_item ==
                            ((ih_item_len(ih) / UNFM_P_SIZE) - 1)) {
                                set_buffer_boundary(bh_result);
                        }
                } else
                        /*
                         * We do not return -ENOENT if there is a hole but
                         * page is uptodate, because it means that there is
                         * some MMAPED data associated with it that is
                         * yet to be written to disk.
                         */
                if ((args & GET_BLOCK_NO_HOLE)
                            && !PageUptodate(bh_result->b_page)) {
                        ret = -ENOENT;
                }

                pathrelse(&path);
                if (p)
                        kunmap(bh_result->b_page);
                return ret;
        }
        /* requested data are in direct item(s) */
        if (!(args & GET_BLOCK_READ_DIRECT)) {
                /*
                 * we are called by bmap. FIXME: we can not map block of file
                 * when it is stored in direct item(s)
                 */
                pathrelse(&path);
                if (p)
                        kunmap(bh_result->b_page);
                return -ENOENT;
        }

        /*
         * if we've got a direct item, and the buffer or page was uptodate,
         * we don't want to pull data off disk again.  skip to the
         * end, where we map the buffer and return
         */
        if (buffer_uptodate(bh_result)) {
                goto finished;
        } else
                /*
                 * grab_tail_page can trigger calls to reiserfs_get_block on
                 * up to date pages without any buffers.  If the page is up
                 * to date, we don't want read old data off disk.  Set the up
                 * to date bit on the buffer instead and jump to the end
                 */
        if (!bh_result->b_page || PageUptodate(bh_result->b_page)) {
                set_buffer_uptodate(bh_result);
                goto finished;
        }
        /* read file tail into part of page */
        offset = (cpu_key_k_offset(&key) - 1) & (PAGE_SIZE - 1);
        copy_item_head(&tmp_ih, ih);

        /*
         * we only want to kmap if we are reading the tail into the page.
         * this is not the common case, so we don't kmap until we are
         * sure we need to.  But, this means the item might move if
         * kmap schedules
         */
        if (!p)
                p = (char *)kmap(bh_result->b_page);

        p += offset;
        memset(p, 0, inode->i_sb->s_blocksize);
        do {
                if (!is_direct_le_ih(ih)) {
                        BUG();
                }
                /*
                 * make sure we don't read more bytes than actually exist in
                 * the file.  This can happen in odd cases where i_size isn't
                 * correct, and when direct item padding results in a few
                 * extra bytes at the end of the direct item
                 */
                if ((le_ih_k_offset(ih) + path.pos_in_item) > inode->i_size)
                        break;
                if ((le_ih_k_offset(ih) - 1 + ih_item_len(ih)) > inode->i_size) {
                        chars =
                            inode->i_size - (le_ih_k_offset(ih) - 1) -
                            path.pos_in_item;
                        done = 1;
                } else {
                        chars = ih_item_len(ih) - path.pos_in_item;
                }
                memcpy(p, ih_item_body(bh, ih) + path.pos_in_item, chars);

                if (done)
                        break;

                p += chars;

                /*
                 * we done, if read direct item is not the last item of
                 * node FIXME: we could try to check right delimiting key
                 * to see whether direct item continues in the right
                 * neighbor or rely on i_size
                 */
                if (PATH_LAST_POSITION(&path) != (B_NR_ITEMS(bh) - 1))
                        break;

                /* update key to look for the next piece */
                set_cpu_key_k_offset(&key, cpu_key_k_offset(&key) + chars);
                result = search_for_position_by_key(inode->i_sb, &key, &path);
                if (result != POSITION_FOUND)
                        /* i/o error most likely */
                        break;
                bh = get_last_bh(&path);
                ih = tp_item_head(&path);
        } while (1);

        flush_dcache_page(bh_result->b_page);
        kunmap(bh_result->b_page);

finished:
        pathrelse(&path);

        if (result == IO_ERROR)
                return -EIO;

        /*
         * this buffer has valid data, but isn't valid for io.  mapping it to
         * block #0 tells the rest of reiserfs it just has a tail in it
         */
        map_bh(bh_result, inode->i_sb, 0);
        set_buffer_uptodate(bh_result);
        return 0;
}

/*
 * this is called to create file map. So, _get_block_create_0 will not
 * read direct item
 */
static int reiserfs_bmap(struct inode *inode, sector_t block,
                         struct buffer_head *bh_result, int create)
{
        if (!file_capable(inode, block))
                return -EFBIG;

        reiserfs_write_lock(inode->i_sb);
        /* do not read the direct item */
        _get_block_create_0(inode, block, bh_result, 0);
        reiserfs_write_unlock(inode->i_sb);
        return 0;
}

/*
 * special version of get_block that is only used by grab_tail_page right
 * now.  It is sent to __block_write_begin, and when you try to get a
 * block past the end of the file (or a block from a hole) it returns
 * -ENOENT instead of a valid buffer.  __block_write_begin expects to
 * be able to do i/o on the buffers returned, unless an error value
 * is also returned.
 *
 * So, this allows __block_write_begin to be used for reading a single block
 * in a page.  Where it does not produce a valid page for holes, or past the
 * end of the file.  This turns out to be exactly what we need for reading
 * tails for conversion.
 *
 * The point of the wrapper is forcing a certain value for create, even
 * though the VFS layer is calling this function with create==1.  If you
 * don't want to send create == GET_BLOCK_NO_HOLE to reiserfs_get_block,
 * don't use this function.
*/
static int reiserfs_get_block_create_0(struct inode *inode, sector_t block,
                                       struct buffer_head *bh_result,
                                       int create)
{
        return reiserfs_get_block(inode, block, bh_result, GET_BLOCK_NO_HOLE);
}

/*
 * This is special helper for reiserfs_get_block in case we are executing
 * direct_IO request.
 */
static int reiserfs_get_blocks_direct_io(struct inode *inode,
                                         sector_t iblock,
                                         struct buffer_head *bh_result,
                                         int create)
{
        int ret;

        bh_result->b_page = NULL;

        /*
         * We set the b_size before reiserfs_get_block call since it is
         * referenced in convert_tail_for_hole() that may be called from
         * reiserfs_get_block()
         */
        bh_result->b_size = i_blocksize(inode);

        ret = reiserfs_get_block(inode, iblock, bh_result,
                                 create | GET_BLOCK_NO_DANGLE);
        if (ret)
                goto out;

        /* don't allow direct io onto tail pages */
        if (buffer_mapped(bh_result) && bh_result->b_blocknr == 0) {
                /*
                 * make sure future calls to the direct io funcs for this
                 * offset in the file fail by unmapping the buffer
                 */
                clear_buffer_mapped(bh_result);
                ret = -EINVAL;
        }

        /*
         * Possible unpacked tail. Flush the data before pages have
         * disappeared
         */
        if (REISERFS_I(inode)->i_flags & i_pack_on_close_mask) {
                int err;

                reiserfs_write_lock(inode->i_sb);

                err = reiserfs_commit_for_inode(inode);
                REISERFS_I(inode)->i_flags &= ~i_pack_on_close_mask;

                reiserfs_write_unlock(inode->i_sb);

                if (err < 0)
                        ret = err;
        }
out:
        return ret;
}

/*
 * helper function for when reiserfs_get_block is called for a hole
 * but the file tail is still in a direct item
 * bh_result is the buffer head for the hole
 * tail_offset is the offset of the start of the tail in the file
 *
 * This calls prepare_write, which will start a new transaction
 * you should not be in a transaction, or have any paths held when you
 * call this.
 */
static int convert_tail_for_hole(struct inode *inode,
                                 struct buffer_head *bh_result,
                                 loff_t tail_offset)
{
        unsigned long index;
        unsigned long tail_end;
        unsigned long tail_start;
        struct page *tail_page;
        struct page *hole_page = bh_result->b_page;
        int retval = 0;

        if ((tail_offset & (bh_result->b_size - 1)) != 1)
                return -EIO;

        /* always try to read until the end of the block */
        tail_start = tail_offset & (PAGE_SIZE - 1);
        tail_end = (tail_start | (bh_result->b_size - 1)) + 1;

        index = tail_offset >> PAGE_SHIFT;
        /*
         * hole_page can be zero in case of direct_io, we are sure
         * that we cannot get here if we write with O_DIRECT into tail page
         */
        if (!hole_page || index != hole_page->index) {
                tail_page = grab_cache_page(inode->i_mapping, index);
                retval = -ENOMEM;
                if (!tail_page) {
                        goto out;
                }
        } else {
                tail_page = hole_page;
        }

        /*
         * we don't have to make sure the conversion did not happen while
         * we were locking the page because anyone that could convert
         * must first take i_mutex.
         *
         * We must fix the tail page for writing because it might have buffers
         * that are mapped, but have a block number of 0.  This indicates tail
         * data that has been read directly into the page, and
         * __block_write_begin won't trigger a get_block in this case.
         */
        fix_tail_page_for_writing(tail_page);
        retval = __reiserfs_write_begin(tail_page, tail_start,
                                      tail_end - tail_start);
        if (retval)
                goto unlock;

        /* tail conversion might change the data in the page */
        flush_dcache_page(tail_page);

        retval = reiserfs_commit_write(NULL, tail_page, tail_start, tail_end);

unlock:
        if (tail_page != hole_page) {
                unlock_page(tail_page);
                put_page(tail_page);
        }
out:
        return retval;
}

static inline int _allocate_block(struct reiserfs_transaction_handle *th,
                                  sector_t block,
                                  struct inode *inode,
                                  b_blocknr_t * allocated_block_nr,
                                  struct treepath *path, int flags)
{
        BUG_ON(!th->t_trans_id);

#ifdef REISERFS_PREALLOCATE
        if (!(flags & GET_BLOCK_NO_IMUX)) {
                return reiserfs_new_unf_blocknrs2(th, inode, allocated_block_nr,
                                                  path, block);
        }
#endif
        return reiserfs_new_unf_blocknrs(th, inode, allocated_block_nr, path,
                                         block);
}

int reiserfs_get_block(struct inode *inode, sector_t block,
                       struct buffer_head *bh_result, int create)
{
        int repeat, retval = 0;
        /* b_blocknr_t is (unsigned) 32 bit int*/
        b_blocknr_t allocated_block_nr = 0;
        INITIALIZE_PATH(path);
        int pos_in_item;
        struct cpu_key key;
        struct buffer_head *bh, *unbh = NULL;
        struct item_head *ih, tmp_ih;
        __le32 *item;
        int done;
        int fs_gen;
        struct reiserfs_transaction_handle *th = NULL;
        /*
         * space reserved in transaction batch:
         * . 3 balancings in direct->indirect conversion
         * . 1 block involved into reiserfs_update_sd()
         * XXX in practically impossible worst case direct2indirect()
         * can incur (much) more than 3 balancings.
         * quota update for user, group
         */
        int jbegin_count =
            JOURNAL_PER_BALANCE_CNT * 3 + 1 +
            2 * REISERFS_QUOTA_TRANS_BLOCKS(inode->i_sb);
        int version;
        int dangle = 1;
        loff_t new_offset =
            (((loff_t) block) << inode->i_sb->s_blocksize_bits) + 1;

        reiserfs_write_lock(inode->i_sb);
        version = get_inode_item_key_version(inode);

        if (!file_capable(inode, block)) {
                reiserfs_write_unlock(inode->i_sb);
                return -EFBIG;
        }

        /*
         * if !create, we aren't changing the FS, so we don't need to
         * log anything, so we don't need to start a transaction
         */
        if (!(create & GET_BLOCK_CREATE)) {
                int ret;
                /* find number of block-th logical block of the file */
                ret = _get_block_create_0(inode, block, bh_result,
                                          create | GET_BLOCK_READ_DIRECT);
                reiserfs_write_unlock(inode->i_sb);
                return ret;
        }

        /*
         * if we're already in a transaction, make sure to close
         * any new transactions we start in this func
         */
        if ((create & GET_BLOCK_NO_DANGLE) ||
            reiserfs_transaction_running(inode->i_sb))
                dangle = 0;

        /*
         * If file is of such a size, that it might have a tail and
         * tails are enabled  we should mark it as possibly needing
         * tail packing on close
         */
        if ((have_large_tails(inode->i_sb)
             && inode->i_size < i_block_size(inode) * 4)
            || (have_small_tails(inode->i_sb)
                && inode->i_size < i_block_size(inode)))
                REISERFS_I(inode)->i_flags |= i_pack_on_close_mask;

        /* set the key of the first byte in the 'block'-th block of file */
        make_cpu_key(&key, inode, new_offset, TYPE_ANY, 3 /*key length */ );
        if ((new_offset + inode->i_sb->s_blocksize - 1) > inode->i_size) {
start_trans:
                th = reiserfs_persistent_transaction(inode->i_sb, jbegin_count);
                if (!th) {
                        retval = -ENOMEM;
                        goto failure;
                }
                reiserfs_update_inode_transaction(inode);
        }
research:

        retval = search_for_position_by_key(inode->i_sb, &key, &path);
        if (retval == IO_ERROR) {
                retval = -EIO;
                goto failure;
        }

        bh = get_last_bh(&path);
        ih = tp_item_head(&path);
        item = tp_item_body(&path);
        pos_in_item = path.pos_in_item;

        fs_gen = get_generation(inode->i_sb);
        copy_item_head(&tmp_ih, ih);

        if (allocation_needed
            (retval, allocated_block_nr, ih, item, pos_in_item)) {
                /* we have to allocate block for the unformatted node */
                if (!th) {
                        pathrelse(&path);
                        goto start_trans;
                }

                repeat =
                    _allocate_block(th, block, inode, &allocated_block_nr,
                                    &path, create);

                /*
                 * restart the transaction to give the journal a chance to free
                 * some blocks.  releases the path, so we have to go back to
                 * research if we succeed on the second try
                 */
                if (repeat == NO_DISK_SPACE || repeat == QUOTA_EXCEEDED) {
                        SB_JOURNAL(inode->i_sb)->j_next_async_flush = 1;
                        retval = restart_transaction(th, inode, &path);
                        if (retval)
                                goto failure;
                        repeat =
                            _allocate_block(th, block, inode,
                                            &allocated_block_nr, NULL, create);

                        if (repeat != NO_DISK_SPACE && repeat != QUOTA_EXCEEDED) {
                                goto research;
                        }
                        if (repeat == QUOTA_EXCEEDED)
                                retval = -EDQUOT;
                        else
                                retval = -ENOSPC;
                        goto failure;
                }

                if (fs_changed(fs_gen, inode->i_sb)
                    && item_moved(&tmp_ih, &path)) {
                        goto research;
                }
        }

        if (indirect_item_found(retval, ih)) {
                b_blocknr_t unfm_ptr;
                /*
                 * 'block'-th block is in the file already (there is
                 * corresponding cell in some indirect item). But it may be
                 * zero unformatted node pointer (hole)
                 */
                unfm_ptr = get_block_num(item, pos_in_item);
                if (unfm_ptr == 0) {
                        /* use allocated block to plug the hole */
                        reiserfs_prepare_for_journal(inode->i_sb, bh, 1);
                        if (fs_changed(fs_gen, inode->i_sb)
                            && item_moved(&tmp_ih, &path)) {
                                reiserfs_restore_prepared_buffer(inode->i_sb,
                                                                 bh);
                                goto research;
                        }
                        set_buffer_new(bh_result);
                        if (buffer_dirty(bh_result)
                            && reiserfs_data_ordered(inode->i_sb))
                                reiserfs_add_ordered_list(inode, bh_result);
                        put_block_num(item, pos_in_item, allocated_block_nr);
                        unfm_ptr = allocated_block_nr;
                        journal_mark_dirty(th, bh);
                        reiserfs_update_sd(th, inode);
                }
                set_block_dev_mapped(bh_result, unfm_ptr, inode);
                pathrelse(&path);
                retval = 0;
                if (!dangle && th)
                        retval = reiserfs_end_persistent_transaction(th);

                reiserfs_write_unlock(inode->i_sb);

                /*
                 * the item was found, so new blocks were not added to the file
                 * there is no need to make sure the inode is updated with this
                 * transaction
                 */
                return retval;
        }

        if (!th) {
                pathrelse(&path);
                goto start_trans;
        }

        /*
         * desired position is not found or is in the direct item. We have
         * to append file with holes up to 'block'-th block converting
         * direct items to indirect one if necessary
         */
        done = 0;
        do {
                if (is_statdata_le_ih(ih)) {
                        __le32 unp = 0;
                        struct cpu_key tmp_key;

                        /* indirect item has to be inserted */
                        make_le_item_head(&tmp_ih, &key, version, 1,
                                          TYPE_INDIRECT, UNFM_P_SIZE,
                                          0 /* free_space */ );

                        /*
                         * we are going to add 'block'-th block to the file.
                         * Use allocated block for that
                         */
                        if (cpu_key_k_offset(&key) == 1) {
                                unp = cpu_to_le32(allocated_block_nr);
                                set_block_dev_mapped(bh_result,
                                                     allocated_block_nr, inode);
                                set_buffer_new(bh_result);
                                done = 1;
                        }
                        tmp_key = key;  /* ;) */
                        set_cpu_key_k_offset(&tmp_key, 1);
                        PATH_LAST_POSITION(&path)++;

                        retval =
                            reiserfs_insert_item(th, &path, &tmp_key, &tmp_ih,
                                                 inode, (char *)&unp);
                        if (retval) {
                                reiserfs_free_block(th, inode,
                                                    allocated_block_nr, 1);
                                /*
                                 * retval == -ENOSPC, -EDQUOT or -EIO
                                 * or -EEXIST
                                 */
                                goto failure;
                        }
                } else if (is_direct_le_ih(ih)) {
                        /* direct item has to be converted */
                        loff_t tail_offset;

                        tail_offset =
                            ((le_ih_k_offset(ih) -
                              1) & ~(inode->i_sb->s_blocksize - 1)) + 1;

                        /*
                         * direct item we just found fits into block we have
                         * to map. Convert it into unformatted node: use
                         * bh_result for the conversion
                         */
                        if (tail_offset == cpu_key_k_offset(&key)) {
                                set_block_dev_mapped(bh_result,
                                                     allocated_block_nr, inode);
                                unbh = bh_result;
                                done = 1;
                        } else {
                                /*
                                 * we have to pad file tail stored in direct
                                 * item(s) up to block size and convert it
                                 * to unformatted node. FIXME: this should
                                 * also get into page cache
                                 */

                                pathrelse(&path);
                                /*
                                 * ugly, but we can only end the transaction if
                                 * we aren't nested
                                 */
                                BUG_ON(!th->t_refcount);
                                if (th->t_refcount == 1) {
                                        retval =
                                            reiserfs_end_persistent_transaction
                                            (th);
                                        th = NULL;
                                        if (retval)
                                                goto failure;
                                }

                                retval =
                                    convert_tail_for_hole(inode, bh_result,
                                                          tail_offset);
                                if (retval) {
                                        if (retval != -ENOSPC)
                                                reiserfs_error(inode->i_sb,
                                                        "clm-6004",
                                                        "convert tail failed "
                                                        "inode %lu, error %d",
                                                        inode->i_ino,
                                                        retval);
                                        if (allocated_block_nr) {
                                                /*
                                                 * the bitmap, the super,
                                                 * and the stat data == 3
                                                 */
                                                if (!th)
                                                        th = reiserfs_persistent_transaction(inode->i_sb, 3);
                                                if (th)
                                                        reiserfs_free_block(th,
                                                                            inode,
                                                                            allocated_block_nr,
                                                                            1);
                                        }
                                        goto failure;
                                }
                                goto research;
                        }
                        retval =
                            direct2indirect(th, inode, &path, unbh,
                                            tail_offset);
                        if (retval) {
                                reiserfs_unmap_buffer(unbh);
                                reiserfs_free_block(th, inode,
                                                    allocated_block_nr, 1);
                                goto failure;
                        }
                        /*
                         * it is important the set_buffer_uptodate is done
                         * after the direct2indirect.  The buffer might
                         * contain valid data newer than the data on disk
                         * (read by readpage, changed, and then sent here by
                         * writepage).  direct2indirect needs to know if unbh
                         * was already up to date, so it can decide if the
                         * data in unbh needs to be replaced with data from
                         * the disk
                         */
                        set_buffer_uptodate(unbh);

                        /*
                         * unbh->b_page == NULL in case of DIRECT_IO request,
                         * this means buffer will disappear shortly, so it
                         * should not be added to
                         */
                        if (unbh->b_page) {
                                /*
                                 * we've converted the tail, so we must
                                 * flush unbh before the transaction commits
                                 */
                                reiserfs_add_tail_list(inode, unbh);

                                /*
                                 * mark it dirty now to prevent commit_write
                                 * from adding this buffer to the inode's
                                 * dirty buffer list
                                 */
                                /*
                                 * AKPM: changed __mark_buffer_dirty to
                                 * mark_buffer_dirty().  It's still atomic,
                                 * but it sets the page dirty too, which makes
                                 * it eligible for writeback at any time by the
                                 * VM (which was also the case with
                                 * __mark_buffer_dirty())

                                 */
                                mark_buffer_dirty(unbh);
                        }
                } else {
                        /*
                         * append indirect item with holes if needed, when
                         * appending pointer to 'block'-th block use block,
                         * which is already allocated
                         */
                        struct cpu_key tmp_key;
                        /*
                         * We use this in case we need to allocate
                         * only one block which is a fastpath
                         */
                        unp_t unf_single = 0;
                        unp_t *un;
                        __u64 max_to_insert =
                            MAX_ITEM_LEN(inode->i_sb->s_blocksize) /
                            UNFM_P_SIZE;
                        __u64 blocks_needed;

                        RFALSE(pos_in_item != ih_item_len(ih) / UNFM_P_SIZE,
                               "vs-804: invalid position for append");
                        /*
                         * indirect item has to be appended,
                         * set up key of that position
                         * (key type is unimportant)
                         */
                        make_cpu_key(&tmp_key, inode,
                                     le_key_k_offset(version,
                                                     &ih->ih_key) +
                                     op_bytes_number(ih,
                                                     inode->i_sb->s_blocksize),
                                     TYPE_INDIRECT, 3);

                        RFALSE(cpu_key_k_offset(&tmp_key) > cpu_key_k_offset(&key),
                               "green-805: invalid offset");
                        blocks_needed =
                            1 +
                            ((cpu_key_k_offset(&key) -
                              cpu_key_k_offset(&tmp_key)) >> inode->i_sb->
                             s_blocksize_bits);

                        if (blocks_needed == 1) {
                                un = &unf_single;
                        } else {
                                un = kcalloc(min(blocks_needed, max_to_insert),
                                             UNFM_P_SIZE, GFP_NOFS);
                                if (!un) {
                                        un = &unf_single;
                                        blocks_needed = 1;
                                        max_to_insert = 0;
                                }
                        }
                        if (blocks_needed <= max_to_insert) {
                                /*
                                 * we are going to add target block to
                                 * the file. Use allocated block for that
                                 */
                                un[blocks_needed - 1] =
                                    cpu_to_le32(allocated_block_nr);
                                set_block_dev_mapped(bh_result,
                                                     allocated_block_nr, inode);
                                set_buffer_new(bh_result);
                                done = 1;
                        } else {
                                /* paste hole to the indirect item */
                                /*
                                 * If kcalloc failed, max_to_insert becomes
                                 * zero and it means we only have space for
                                 * one block
                                 */
                                blocks_needed =
                                    max_to_insert ? max_to_insert : 1;
                        }
                        retval =
                            reiserfs_paste_into_item(th, &path, &tmp_key, inode,
                                                     (char *)un,
                                                     UNFM_P_SIZE *
                                                     blocks_needed);

                        if (blocks_needed != 1)
                                kfree(un);

                        if (retval) {
                                reiserfs_free_block(th, inode,
                                                    allocated_block_nr, 1);
                                goto failure;
                        }
                        if (!done) {
                                /*
                                 * We need to mark new file size in case
                                 * this function will be interrupted/aborted
                                 * later on. And we may do this only for
                                 * holes.
                                 */
                                inode->i_size +=
                                    inode->i_sb->s_blocksize * blocks_needed;
                        }
                }

                if (done == 1)
                        break;

                /*
                 * this loop could log more blocks than we had originally
                 * asked for.  So, we have to allow the transaction to end
                 * if it is too big or too full.  Update the inode so things
                 * are consistent if we crash before the function returns
                 * release the path so that anybody waiting on the path before
                 * ending their transaction will be able to continue.
                 */
                if (journal_transaction_should_end(th, th->t_blocks_allocated)) {
                        retval = restart_transaction(th, inode, &path);
                        if (retval)
                                goto failure;
                }
                /*
                 * inserting indirect pointers for a hole can take a
                 * long time.  reschedule if needed and also release the write
                 * lock for others.
                 */
                reiserfs_cond_resched(inode->i_sb);

                retval = search_for_position_by_key(inode->i_sb, &key, &path);
                if (retval == IO_ERROR) {
                        retval = -EIO;
                        goto failure;
                }
                if (retval == POSITION_FOUND) {
                        reiserfs_warning(inode->i_sb, "vs-825",
                                         "%K should not be found", &key);
                        retval = -EEXIST;
                        if (allocated_block_nr)
                                reiserfs_free_block(th, inode,
                                                    allocated_block_nr, 1);
                        pathrelse(&path);
                        goto failure;
                }
                bh = get_last_bh(&path);
                ih = tp_item_head(&path);
                item = tp_item_body(&path);
                pos_in_item = path.pos_in_item;
        } while (1);

        retval = 0;

failure:
        if (th && (!dangle || (retval && !th->t_trans_id))) {
                int err;
                if (th->t_trans_id)
                        reiserfs_update_sd(th, inode);
                err = reiserfs_end_persistent_transaction(th);
                if (err)
                        retval = err;
        }

        reiserfs_write_unlock(inode->i_sb);
        reiserfs_check_path(&path);
        return retval;
}

static void reiserfs_readahead(struct readahead_control *rac)
{
        mpage_readahead(rac, reiserfs_get_block);
}

/*
 * Compute real number of used bytes by file
 * Following three functions can go away when we'll have enough space in
 * stat item
 */
static int real_space_diff(struct inode *inode, int sd_size)
{
        int bytes;
        loff_t blocksize = inode->i_sb->s_blocksize;

        if (S_ISLNK(inode->i_mode) || S_ISDIR(inode->i_mode))
                return sd_size;

        /*
         * End of file is also in full block with indirect reference, so round
         * up to the next block.
         *
         * there is just no way to know if the tail is actually packed
         * on the file, so we have to assume it isn't.  When we pack the
         * tail, we add 4 bytes to pretend there really is an unformatted
         * node pointer
         */
        bytes =
            ((inode->i_size +
              (blocksize - 1)) >> inode->i_sb->s_blocksize_bits) * UNFM_P_SIZE +
            sd_size;
        return bytes;
}

static inline loff_t to_real_used_space(struct inode *inode, ulong blocks,
                                        int sd_size)
{
        if (S_ISLNK(inode->i_mode) || S_ISDIR(inode->i_mode)) {
                return inode->i_size +
                    (loff_t) (real_space_diff(inode, sd_size));
        }
        return ((loff_t) real_space_diff(inode, sd_size)) +
            (((loff_t) blocks) << 9);
}

/* Compute number of blocks used by file in ReiserFS counting */
static inline ulong to_fake_used_blocks(struct inode *inode, int sd_size)
{
        loff_t bytes = inode_get_bytes(inode);
        loff_t real_space = real_space_diff(inode, sd_size);

        /* keeps fsck and non-quota versions of reiserfs happy */
        if (S_ISLNK(inode->i_mode) || S_ISDIR(inode->i_mode)) {
                bytes += (loff_t) 511;
        }

        /*
         * files from before the quota patch might i_blocks such that
         * bytes < real_space.  Deal with that here to prevent it from
         * going negative.
         */
        if (bytes < real_space)
                return 0;
        return (bytes - real_space) >> 9;
}

/*
 * BAD: new directories have stat data of new type and all other items
 * of old type. Version stored in the inode says about body items, so
 * in update_stat_data we can not rely on inode, but have to check
 * item version directly
 */

/* called by read_locked_inode */
static void init_inode(struct inode *inode, struct treepath *path)
{
        struct buffer_head *bh;
        struct item_head *ih;
        __u32 rdev;

        bh = PATH_PLAST_BUFFER(path);
        ih = tp_item_head(path);

        copy_key(INODE_PKEY(inode), &ih->ih_key);

        INIT_LIST_HEAD(&REISERFS_I(inode)->i_prealloc_list);
        REISERFS_I(inode)->i_flags = 0;
        REISERFS_I(inode)->i_prealloc_block = 0;
        REISERFS_I(inode)->i_prealloc_count = 0;
        REISERFS_I(inode)->i_trans_id = 0;
        REISERFS_I(inode)->i_jl = NULL;
        reiserfs_init_xattr_rwsem(inode);

        if (stat_data_v1(ih)) {
                struct stat_data_v1 *sd =
                    (struct stat_data_v1 *)ih_item_body(bh, ih);
                unsigned long blocks;

                set_inode_item_key_version(inode, KEY_FORMAT_3_5);
                set_inode_sd_version(inode, STAT_DATA_V1);
                inode->i_mode = sd_v1_mode(sd);
                set_nlink(inode, sd_v1_nlink(sd));
                i_uid_write(inode, sd_v1_uid(sd));
                i_gid_write(inode, sd_v1_gid(sd));
                inode->i_size = sd_v1_size(sd);
                inode->i_atime.tv_sec = sd_v1_atime(sd);
                inode->i_mtime.tv_sec = sd_v1_mtime(sd);
                inode->i_ctime.tv_sec = sd_v1_ctime(sd);
                inode->i_atime.tv_nsec = 0;
                inode->i_ctime.tv_nsec = 0;
                inode->i_mtime.tv_nsec = 0;

                inode->i_blocks = sd_v1_blocks(sd);
                inode->i_generation = le32_to_cpu(INODE_PKEY(inode)->k_dir_id);
                blocks = (inode->i_size + 511) >> 9;
                blocks = _ROUND_UP(blocks, inode->i_sb->s_blocksize >> 9);

                /*
                 * there was a bug in <=3.5.23 when i_blocks could take
                 * negative values. Starting from 3.5.17 this value could
                 * even be stored in stat data. For such files we set
                 * i_blocks based on file size. Just 2 notes: this can be
                 * wrong for sparse files. On-disk value will be only
                 * updated if file's inode will ever change
                 */
                if (inode->i_blocks > blocks) {
                        inode->i_blocks = blocks;
                }

                rdev = sd_v1_rdev(sd);
                REISERFS_I(inode)->i_first_direct_byte =
                    sd_v1_first_direct_byte(sd);

                /*
                 * an early bug in the quota code can give us an odd
                 * number for the block count.  This is incorrect, fix it here.
                 */
                if (inode->i_blocks & 1) {
                        inode->i_blocks++;
                }
                inode_set_bytes(inode,
                                to_real_used_space(inode, inode->i_blocks,
                                                   SD_V1_SIZE));
                /*
                 * nopack is initially zero for v1 objects. For v2 objects,
                 * nopack is initialised from sd_attrs
                 */
                REISERFS_I(inode)->i_flags &= ~i_nopack_mask;
        } else {
                /*
                 * new stat data found, but object may have old items
                 * (directories and symlinks)
                 */
                struct stat_data *sd = (struct stat_data *)ih_item_body(bh, ih);

                inode->i_mode = sd_v2_mode(sd);
                set_nlink(inode, sd_v2_nlink(sd));
                i_uid_write(inode, sd_v2_uid(sd));
                inode->i_size = sd_v2_size(sd);
                i_gid_write(inode, sd_v2_gid(sd));
                inode->i_mtime.tv_sec = sd_v2_mtime(sd);
                inode->i_atime.tv_sec = sd_v2_atime(sd);
                inode->i_ctime.tv_sec = sd_v2_ctime(sd);
                inode->i_ctime.tv_nsec = 0;
                inode->i_mtime.tv_nsec = 0;
                inode->i_atime.tv_nsec = 0;
                inode->i_blocks = sd_v2_blocks(sd);
                rdev = sd_v2_rdev(sd);
                if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode))
                        inode->i_generation =
                            le32_to_cpu(INODE_PKEY(inode)->k_dir_id);
                else
                        inode->i_generation = sd_v2_generation(sd);

                if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
                        set_inode_item_key_version(inode, KEY_FORMAT_3_5);
                else
                        set_inode_item_key_version(inode, KEY_FORMAT_3_6);
                REISERFS_I(inode)->i_first_direct_byte = 0;
                set_inode_sd_version(inode, STAT_DATA_V2);
                inode_set_bytes(inode,
                                to_real_used_space(inode, inode->i_blocks,
                                                   SD_V2_SIZE));
                /*
                 * read persistent inode attributes from sd and initialise
                 * generic inode flags from them
                 */
                REISERFS_I(inode)->i_attrs = sd_v2_attrs(sd);
                sd_attrs_to_i_attrs(sd_v2_attrs(sd), inode);
        }

        pathrelse(path);
        if (S_ISREG(inode->i_mode)) {
                inode->i_op = &reiserfs_file_inode_operations;
                inode->i_fop = &reiserfs_file_operations;
                inode->i_mapping->a_ops = &reiserfs_address_space_operations;
        } else if (S_ISDIR(inode->i_mode)) {
                inode->i_op = &reiserfs_dir_inode_operations;
                inode->i_fop = &reiserfs_dir_operations;
        } else if (S_ISLNK(inode->i_mode)) {
                inode->i_op = &reiserfs_symlink_inode_operations;
                inode_nohighmem(inode);
                inode->i_mapping->a_ops = &reiserfs_address_space_operations;
        } else {
                inode->i_blocks = 0;
                inode->i_op = &reiserfs_special_inode_operations;
                init_special_inode(inode, inode->i_mode, new_decode_dev(rdev));
        }
}

/* update new stat data with inode fields */
static void inode2sd(void *sd, struct inode *inode, loff_t size)
{
        struct stat_data *sd_v2 = (struct stat_data *)sd;

        set_sd_v2_mode(sd_v2, inode->i_mode);
        set_sd_v2_nlink(sd_v2, inode->i_nlink);
        set_sd_v2_uid(sd_v2, i_uid_read(inode));
        set_sd_v2_size(sd_v2, size);
        set_sd_v2_gid(sd_v2, i_gid_read(inode));
        set_sd_v2_mtime(sd_v2, inode->i_mtime.tv_sec);
        set_sd_v2_atime(sd_v2, inode->i_atime.tv_sec);
        set_sd_v2_ctime(sd_v2, inode->i_ctime.tv_sec);
        set_sd_v2_blocks(sd_v2, to_fake_used_blocks(inode, SD_V2_SIZE));
        if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode))
                set_sd_v2_rdev(sd_v2, new_encode_dev(inode->i_rdev));
        else
                set_sd_v2_generation(sd_v2, inode->i_generation);
        set_sd_v2_attrs(sd_v2, REISERFS_I(inode)->i_attrs);
}

/* used to copy inode's fields to old stat data */
static void inode2sd_v1(void *sd, struct inode *inode, loff_t size)
{
        struct stat_data_v1 *sd_v1 = (struct stat_data_v1 *)sd;

        set_sd_v1_mode(sd_v1, inode->i_mode);
        set_sd_v1_uid(sd_v1, i_uid_read(inode));
        set_sd_v1_gid(sd_v1, i_gid_read(inode));
        set_sd_v1_nlink(sd_v1, inode->i_nlink);
        set_sd_v1_size(sd_v1, size);
        set_sd_v1_atime(sd_v1, inode->i_atime.tv_sec);
        set_sd_v1_ctime(sd_v1, inode->i_ctime.tv_sec);
        set_sd_v1_mtime(sd_v1, inode->i_mtime.tv_sec);

        if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode))
                set_sd_v1_rdev(sd_v1, new_encode_dev(inode->i_rdev));
        else
                set_sd_v1_blocks(sd_v1, to_fake_used_blocks(inode, SD_V1_SIZE));

        /* Sigh. i_first_direct_byte is back */
        set_sd_v1_first_direct_byte(sd_v1,
                                    REISERFS_I(inode)->i_first_direct_byte);
}

/*
 * NOTE, you must prepare the buffer head before sending it here,
 * and then log it after the call
 */
static void update_stat_data(struct treepath *path, struct inode *inode,
                             loff_t size)
{
        struct buffer_head *bh;
        struct item_head *ih;

        bh = PATH_PLAST_BUFFER(path);
        ih = tp_item_head(path);

        if (!is_statdata_le_ih(ih))
                reiserfs_panic(inode->i_sb, "vs-13065", "key %k, found item %h",
                               INODE_PKEY(inode), ih);

        /* path points to old stat data */
        if (stat_data_v1(ih)) {
                inode2sd_v1(ih_item_body(bh, ih), inode, size);
        } else {
                inode2sd(ih_item_body(bh, ih), inode, size);
        }

        return;
}

void reiserfs_update_sd_size(struct reiserfs_transaction_handle *th,
                             struct inode *inode, loff_t size)
{
        struct cpu_key key;
        INITIALIZE_PATH(path);
        struct buffer_head *bh;
        int fs_gen;
        struct item_head *ih, tmp_ih;
        int retval;

        BUG_ON(!th->t_trans_id);

        /* key type is unimportant */
        make_cpu_key(&key, inode, SD_OFFSET, TYPE_STAT_DATA, 3);

        for (;;) {
                int pos;
                /* look for the object's stat data */
                retval = search_item(inode->i_sb, &key, &path);
                if (retval == IO_ERROR) {
                        reiserfs_error(inode->i_sb, "vs-13050",
                                       "i/o failure occurred trying to "
                                       "update %K stat data", &key);
                        return;
                }
                if (retval == ITEM_NOT_FOUND) {
                        pos = PATH_LAST_POSITION(&path);
                        pathrelse(&path);
                        if (inode->i_nlink == 0) {
                                /*reiserfs_warning (inode->i_sb, "vs-13050: reiserfs_update_sd: i_nlink == 0, stat data not found"); */
                                return;
                        }
                        reiserfs_warning(inode->i_sb, "vs-13060",
                                         "stat data of object %k (nlink == %d) "
                                         "not found (pos %d)",
                                         INODE_PKEY(inode), inode->i_nlink,
                                         pos);
                        reiserfs_check_path(&path);
                        return;
                }

                /*
                 * sigh, prepare_for_journal might schedule.  When it
                 * schedules the FS might change.  We have to detect that,
                 * and loop back to the search if the stat data item has moved
                 */
                bh = get_last_bh(&path);
                ih = tp_item_head(&path);
                copy_item_head(&tmp_ih, ih);
                fs_gen = get_generation(inode->i_sb);
                reiserfs_prepare_for_journal(inode->i_sb, bh, 1);

                /* Stat_data item has been moved after scheduling. */
                if (fs_changed(fs_gen, inode->i_sb)
                    && item_moved(&tmp_ih, &path)) {
                        reiserfs_restore_prepared_buffer(inode->i_sb, bh);
                        continue;
                }
                break;
        }
        update_stat_data(&path, inode, size);
        journal_mark_dirty(th, bh);
        pathrelse(&path);
        return;
}

/*
 * reiserfs_read_locked_inode is called to read the inode off disk, and it
 * does a make_bad_inode when things go wrong.  But, we need to make sure
 * and clear the key in the private portion of the inode, otherwise a
 * corresponding iput might try to delete whatever object the inode last
 * represented.
 */
static void reiserfs_make_bad_inode(struct inode *inode)
{
        memset(INODE_PKEY(inode), 0, KEY_SIZE);
        make_bad_inode(inode);
}

/*
 * initially this function was derived from minix or ext2's analog and
 * evolved as the prototype did
 */
int reiserfs_init_locked_inode(struct inode *inode, void *p)
{
        struct reiserfs_iget_args *args = (struct reiserfs_iget_args *)p;
        inode->i_ino = args->objectid;
        INODE_PKEY(inode)->k_dir_id = cpu_to_le32(args->dirid);
        return 0;
}

/*
 * looks for stat data in the tree, and fills up the fields of in-core
 * inode stat data fields
 */
void reiserfs_read_locked_inode(struct inode *inode,
                                struct reiserfs_iget_args *args)
{
        INITIALIZE_PATH(path_to_sd);
        struct cpu_key key;
        unsigned long dirino;
        int retval;

        dirino = args->dirid;

        /*
         * set version 1, version 2 could be used too, because stat data
         * key is the same in both versions
         */
        _make_cpu_key(&key, KEY_FORMAT_3_5, dirino, inode->i_ino, 0, 0, 3);

        /* look for the object's stat data */
        retval = search_item(inode->i_sb, &key, &path_to_sd);
        if (retval == IO_ERROR) {
                reiserfs_error(inode->i_sb, "vs-13070",
                               "i/o failure occurred trying to find "
                               "stat data of %K", &key);
                reiserfs_make_bad_inode(inode);
                return;
        }

        /* a stale NFS handle can trigger this without it being an error */
        if (retval != ITEM_FOUND) {
                pathrelse(&path_to_sd);
                reiserfs_make_bad_inode(inode);
                clear_nlink(inode);
                return;
        }

        init_inode(inode, &path_to_sd);

        /*
         * It is possible that knfsd is trying to access inode of a file
         * that is being removed from the disk by some other thread. As we
         * update sd on unlink all that is required is to check for nlink
         * here. This bug was first found by Sizif when debugging
         * SquidNG/Butterfly, forgotten, and found again after Philippe
         * Gramoulle <philippe.gramoulle@mmania.com> reproduced it.

         * More logical fix would require changes in fs/inode.c:iput() to
         * remove inode from hash-table _after_ fs cleaned disk stuff up and
         * in iget() to return NULL if I_FREEING inode is found in
         * hash-table.
         */

        /*
         * Currently there is one place where it's ok to meet inode with
         * nlink==0: processing of open-unlinked and half-truncated files
         * during mount (fs/reiserfs/super.c:finish_unfinished()).
         */
        if ((inode->i_nlink == 0) &&
            !REISERFS_SB(inode->i_sb)->s_is_unlinked_ok) {
                reiserfs_warning(inode->i_sb, "vs-13075",
                                 "dead inode read from disk %K. "
                                 "This is likely to be race with knfsd. Ignore",
                                 &key);
                reiserfs_make_bad_inode(inode);
        }

        /* init inode should be relsing */
        reiserfs_check_path(&path_to_sd);

        /*
         * Stat data v1 doesn't support ACLs.
         */
        if (get_inode_sd_version(inode) == STAT_DATA_V1)
                cache_no_acl(inode);
}

/*
 * reiserfs_find_actor() - "find actor" reiserfs supplies to iget5_locked().
 *
 * @inode:    inode from hash table to check
 * @opaque:   "cookie" passed to iget5_locked(). This is &reiserfs_iget_args.
 *
 * This function is called by iget5_locked() to distinguish reiserfs inodes
 * having the same inode numbers. Such inodes can only exist due to some
 * error condition. One of them should be bad. Inodes with identical
 * inode numbers (objectids) are distinguished by parent directory ids.
 *
 */
int reiserfs_find_actor(struct inode *inode, void *opaque)
{
        struct reiserfs_iget_args *args;

        args = opaque;
        /* args is already in CPU order */
        return (inode->i_ino == args->objectid) &&
            (le32_to_cpu(INODE_PKEY(inode)->k_dir_id) == args->dirid);
}

struct inode *reiserfs_iget(struct super_block *s, const struct cpu_key *key)
{
        struct inode *inode;
        struct reiserfs_iget_args args;
        int depth;

        args.objectid = key->on_disk_key.k_objectid;
        args.dirid = key->on_disk_key.k_dir_id;
        depth = reiserfs_write_unlock_nested(s);
        inode = iget5_locked(s, key->on_disk_key.k_objectid,
                             reiserfs_find_actor, reiserfs_init_locked_inode,
                             (void *)(&args));
        reiserfs_write_lock_nested(s, depth);
        if (!inode)
                return ERR_PTR(-ENOMEM);

        if (inode->i_state & I_NEW) {
                reiserfs_read_locked_inode(inode, &args);
                unlock_new_inode(inode);
        }

        if (comp_short_keys(INODE_PKEY(inode), key) || is_bad_inode(inode)) {
                /* either due to i/o error or a stale NFS handle */
                iput(inode);
                inode = NULL;
        }
        return inode;
}

static struct dentry *reiserfs_get_dentry(struct super_block *sb,
        u32 objectid, u32 dir_id, u32 generation)

{
        struct cpu_key key;
        struct inode *inode;

        key.on_disk_key.k_objectid = objectid;
        key.on_disk_key.k_dir_id = dir_id;
        reiserfs_write_lock(sb);
        inode = reiserfs_iget(sb, &key);
        if (inode && !IS_ERR(inode) && generation != 0 &&
            generation != inode->i_generation) {
                iput(inode);
                inode = NULL;
        }
        reiserfs_write_unlock(sb);

        return d_obtain_alias(inode);
}

struct dentry *reiserfs_fh_to_dentry(struct super_block *sb, struct fid *fid,
                int fh_len, int fh_type)
{
        /*
         * fhtype happens to reflect the number of u32s encoded.
         * due to a bug in earlier code, fhtype might indicate there
         * are more u32s then actually fitted.
         * so if fhtype seems to be more than len, reduce fhtype.
         * Valid types are:
         *   2 - objectid + dir_id - legacy support
         *   3 - objectid + dir_id + generation
         *   4 - objectid + dir_id + objectid and dirid of parent - legacy
         *   5 - objectid + dir_id + generation + objectid and dirid of parent
         *   6 - as above plus generation of directory
         * 6 does not fit in NFSv2 handles
         */
        if (fh_type > fh_len) {
                if (fh_type != 6 || fh_len != 5)
                        reiserfs_warning(sb, "reiserfs-13077",
                                "nfsd/reiserfs, fhtype=%d, len=%d - odd",
                                fh_type, fh_len);
                fh_type = fh_len;
        }
        if (fh_len < 2)
                return NULL;

        return reiserfs_get_dentry(sb, fid->raw[0], fid->raw[1],
                (fh_type == 3 || fh_type >= 5) ? fid->raw[2] : 0);
}

struct dentry *reiserfs_fh_to_parent(struct super_block *sb, struct fid *fid,
                int fh_len, int fh_type)
{
        if (fh_type > fh_len)
                fh_type = fh_len;
        if (fh_type < 4)
                return NULL;

        return reiserfs_get_dentry(sb,
                (fh_type >= 5) ? fid->raw[3] : fid->raw[2],
                (fh_type >= 5) ? fid->raw[4] : fid->raw[3],
                (fh_type == 6) ? fid->raw[5] : 0);
}

int reiserfs_encode_fh(struct inode *inode, __u32 * data, int *lenp,
                       struct inode *parent)
{
        int maxlen = *lenp;

        if (parent && (maxlen < 5)) {
                *lenp = 5;
                return FILEID_INVALID;
        } else if (maxlen < 3) {
                *lenp = 3;
                return FILEID_INVALID;
        }

        data[0] = inode->i_ino;
        data[1] = le32_to_cpu(INODE_PKEY(inode)->k_dir_id);
        data[2] = inode->i_generation;
        *lenp = 3;
        if (parent) {
                data[3] = parent->i_ino;
                data[4] = le32_to_cpu(INODE_PKEY(parent)->k_dir_id);
                *lenp = 5;
                if (maxlen >= 6) {
                        data[5] = parent->i_generation;
                        *lenp = 6;
                }
        }
        return *lenp;
}

/*
 * looks for stat data, then copies fields to it, marks the buffer
 * containing stat data as dirty
 */
/*
 * reiserfs inodes are never really dirty, since the dirty inode call
 * always logs them.  This call allows the VFS inode marking routines
 * to properly mark inodes for datasync and such, but only actually
 * does something when called for a synchronous update.
 */
int reiserfs_write_inode(struct inode *inode, struct writeback_control *wbc)
{
        struct reiserfs_transaction_handle th;
        int jbegin_count = 1;

        if (sb_rdonly(inode->i_sb))
                return -EROFS;
        /*
         * memory pressure can sometimes initiate write_inode calls with
         * sync == 1,
         * these cases are just when the system needs ram, not when the
         * inode needs to reach disk for safety, and they can safely be
         * ignored because the altered inode has already been logged.
         */
        if (wbc->sync_mode == WB_SYNC_ALL && !(current->flags & PF_MEMALLOC)) {
                reiserfs_write_lock(inode->i_sb);
                if (!journal_begin(&th, inode->i_sb, jbegin_count)) {
                        reiserfs_update_sd(&th, inode);
                        journal_end_sync(&th);
                }
                reiserfs_write_unlock(inode->i_sb);
        }
        return 0;
}

/*
 * stat data of new object is inserted already, this inserts the item
 * containing "." and ".." entries
 */
static int reiserfs_new_directory(struct reiserfs_transaction_handle *th,
                                  struct inode *inode,
                                  struct item_head *ih, struct treepath *path,
                                  struct inode *dir)
{
        struct super_block *sb = th->t_super;
        char empty_dir[EMPTY_DIR_SIZE];
        char *body = empty_dir;
        struct cpu_key key;
        int retval;

        BUG_ON(!th->t_trans_id);

        _make_cpu_key(&key, KEY_FORMAT_3_5, le32_to_cpu(ih->ih_key.k_dir_id),
                      le32_to_cpu(ih->ih_key.k_objectid), DOT_OFFSET,
                      TYPE_DIRENTRY, 3 /*key length */ );

        /*
         * compose item head for new item. Directories consist of items of
         * old type (ITEM_VERSION_1). Do not set key (second arg is 0), it
         * is done by reiserfs_new_inode
         */
        if (old_format_only(sb)) {
                make_le_item_head(ih, NULL, KEY_FORMAT_3_5, DOT_OFFSET,
                                  TYPE_DIRENTRY, EMPTY_DIR_SIZE_V1, 2);

                make_empty_dir_item_v1(body, ih->ih_key.k_dir_id,
                                       ih->ih_key.k_objectid,
                                       INODE_PKEY(dir)->k_dir_id,
                                       INODE_PKEY(dir)->k_objectid);
        } else {
                make_le_item_head(ih, NULL, KEY_FORMAT_3_5, DOT_OFFSET,
                                  TYPE_DIRENTRY, EMPTY_DIR_SIZE, 2);

                make_empty_dir_item(body, ih->ih_key.k_dir_id,
                                    ih->ih_key.k_objectid,
                                    INODE_PKEY(dir)->k_dir_id,
                                    INODE_PKEY(dir)->k_objectid);
        }

        /* look for place in the tree for new item */
        retval = search_item(sb, &key, path);
        if (retval == IO_ERROR) {
                reiserfs_error(sb, "vs-13080",
                               "i/o failure occurred creating new directory");
                return -EIO;
        }
        if (retval == ITEM_FOUND) {
                pathrelse(path);
                reiserfs_warning(sb, "vs-13070",
                                 "object with this key exists (%k)",
                                 &(ih->ih_key));
                return -EEXIST;
        }

        /* insert item, that is empty directory item */
        return reiserfs_insert_item(th, path, &key, ih, inode, body);
}

/*
 * stat data of object has been inserted, this inserts the item
 * containing the body of symlink
 */
static int reiserfs_new_symlink(struct reiserfs_transaction_handle *th,
                                struct inode *inode,
                                struct item_head *ih,
                                struct treepath *path, const char *symname,
                                int item_len)
{
        struct super_block *sb = th->t_super;
        struct cpu_key key;
        int retval;

        BUG_ON(!th->t_trans_id);

        _make_cpu_key(&key, KEY_FORMAT_3_5,
                      le32_to_cpu(ih->ih_key.k_dir_id),
                      le32_to_cpu(ih->ih_key.k_objectid),
                      1, TYPE_DIRECT, 3 /*key length */ );

        make_le_item_head(ih, NULL, KEY_FORMAT_3_5, 1, TYPE_DIRECT, item_len,
                          0 /*free_space */ );

        /* look for place in the tree for new item */
        retval = search_item(sb, &key, path);
        if (retval == IO_ERROR) {
                reiserfs_error(sb, "vs-13080",
                               "i/o failure occurred creating new symlink");
                return -EIO;
        }
        if (retval == ITEM_FOUND) {
                pathrelse(path);
                reiserfs_warning(sb, "vs-13080",
                                 "object with this key exists (%k)",
                                 &(ih->ih_key));
                return -EEXIST;
        }

        /* insert item, that is body of symlink */
        return reiserfs_insert_item(th, path, &key, ih, inode, symname);
}

/*
 * inserts the stat data into the tree, and then calls
 * reiserfs_new_directory (to insert ".", ".." item if new object is
 * directory) or reiserfs_new_symlink (to insert symlink body if new
 * object is symlink) or nothing (if new object is regular file)

 * NOTE! uid and gid must already be set in the inode.  If we return
 * non-zero due to an error, we have to drop the quota previously allocated
 * for the fresh inode.  This can only be done outside a transaction, so
 * if we return non-zero, we also end the transaction.
 *
 * @th: active transaction handle
 * @dir: parent directory for new inode
 * @mode: mode of new inode
 * @symname: symlink contents if inode is symlink
 * @isize: 0 for regular file, EMPTY_DIR_SIZE for dirs, strlen(symname) for
 *         symlinks
 * @inode: inode to be filled
 * @security: optional security context to associate with this inode
 */
int reiserfs_new_inode(struct reiserfs_transaction_handle *th,
                       struct inode *dir, umode_t mode, const char *symname,
                       /* 0 for regular, EMTRY_DIR_SIZE for dirs,
                          strlen (symname) for symlinks) */
                       loff_t i_size, struct dentry *dentry,
                       struct inode *inode,
                       struct reiserfs_security_handle *security)
{
        struct super_block *sb = dir->i_sb;
        struct reiserfs_iget_args args;
        INITIALIZE_PATH(path_to_key);
        struct cpu_key key;
        struct item_head ih;
        struct stat_data sd;
        int retval;
        int err;
        int depth;

        BUG_ON(!th->t_trans_id);

        depth = reiserfs_write_unlock_nested(sb);
        err = dquot_alloc_inode(inode);
        reiserfs_write_lock_nested(sb, depth);
        if (err)
                goto out_end_trans;
        if (!dir->i_nlink) {
                err = -EPERM;
                goto out_bad_inode;
        }

        /* item head of new item */
        ih.ih_key.k_dir_id = reiserfs_choose_packing(dir);
        ih.ih_key.k_objectid = cpu_to_le32(reiserfs_get_unused_objectid(th));
        if (!ih.ih_key.k_objectid) {
                err = -ENOMEM;
                goto out_bad_inode;
        }
        args.objectid = inode->i_ino = le32_to_cpu(ih.ih_key.k_objectid);
        if (old_format_only(sb))
                make_le_item_head(&ih, NULL, KEY_FORMAT_3_5, SD_OFFSET,
                                  TYPE_STAT_DATA, SD_V1_SIZE, MAX_US_INT);
        else
                make_le_item_head(&ih, NULL, KEY_FORMAT_3_6, SD_OFFSET,
                                  TYPE_STAT_DATA, SD_SIZE, MAX_US_INT);
        memcpy(INODE_PKEY(inode), &ih.ih_key, KEY_SIZE);
        args.dirid = le32_to_cpu(ih.ih_key.k_dir_id);

        depth = reiserfs_write_unlock_nested(inode->i_sb);
        err = insert_inode_locked4(inode, args.objectid,
                             reiserfs_find_actor, &args);
        reiserfs_write_lock_nested(inode->i_sb, depth);
        if (err) {
                err = -EINVAL;
                goto out_bad_inode;
        }

        if (old_format_only(sb))
                /*
                 * not a perfect generation count, as object ids can be reused,
                 * but this is as good as reiserfs can do right now.
                 * note that the private part of inode isn't filled in yet,
                 * we have to use the directory.
                 */
                inode->i_generation = le32_to_cpu(INODE_PKEY(dir)->k_objectid);
        else
#if defined( USE_INODE_GENERATION_COUNTER )
                inode->i_generation =
                    le32_to_cpu(REISERFS_SB(sb)->s_rs->s_inode_generation);
#else
                inode->i_generation = ++event;
#endif

        /* fill stat data */
        set_nlink(inode, (S_ISDIR(mode) ? 2 : 1));

        /* uid and gid must already be set by the caller for quota init */

        inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
        inode->i_size = i_size;
        inode->i_blocks = 0;
        inode->i_bytes = 0;

        REISERFS_I(inode)->i_first_direct_byte = S_ISLNK(mode) ? 1 :
            U32_MAX /*NO_BYTES_IN_DIRECT_ITEM */ ;

        INIT_LIST_HEAD(&REISERFS_I(inode)->i_prealloc_list);
        REISERFS_I(inode)->i_flags = 0;
        REISERFS_I(inode)->i_prealloc_block = 0;
        REISERFS_I(inode)->i_prealloc_count = 0;
        REISERFS_I(inode)->i_trans_id = 0;
        REISERFS_I(inode)->i_jl = NULL;
        REISERFS_I(inode)->i_attrs =
            REISERFS_I(dir)->i_attrs & REISERFS_INHERIT_MASK;
        sd_attrs_to_i_attrs(REISERFS_I(inode)->i_attrs, inode);
        reiserfs_init_xattr_rwsem(inode);

        /* key to search for correct place for new stat data */
        _make_cpu_key(&key, KEY_FORMAT_3_6, le32_to_cpu(ih.ih_key.k_dir_id),
                      le32_to_cpu(ih.ih_key.k_objectid), SD_OFFSET,
                      TYPE_STAT_DATA, 3 /*key length */ );

        /* find proper place for inserting of stat data */
        retval = search_item(sb, &key, &path_to_key);
        if (retval == IO_ERROR) {
                err = -EIO;
                goto out_bad_inode;
        }
        if (retval == ITEM_FOUND) {
                pathrelse(&path_to_key);
                err = -EEXIST;
                goto out_bad_inode;
        }
        if (old_format_only(sb)) {
                /* i_uid or i_gid is too big to be stored in stat data v3.5 */
                if (i_uid_read(inode) & ~0xffff || i_gid_read(inode) & ~0xffff) {
                        pathrelse(&path_to_key);
                        err = -EINVAL;
                        goto out_bad_inode;
                }
                inode2sd_v1(&sd, inode, inode->i_size);
        } else {
                inode2sd(&sd, inode, inode->i_size);
        }
        /*
         * store in in-core inode the key of stat data and version all
         * object items will have (directory items will have old offset
         * format, other new objects will consist of new items)
         */
        if (old_format_only(sb) || S_ISDIR(mode) || S_ISLNK(mode))
                set_inode_item_key_version(inode, KEY_FORMAT_3_5);
        else
                set_inode_item_key_version(inode, KEY_FORMAT_3_6);
        if (old_format_only(sb))
                set_inode_sd_version(inode, STAT_DATA_V1);
        else
                set_inode_sd_version(inode, STAT_DATA_V2);

        /* insert the stat data into the tree */
#ifdef DISPLACE_NEW_PACKING_LOCALITIES
        if (REISERFS_I(dir)->new_packing_locality)
                th->displace_new_blocks = 1;
#endif
        retval =
            reiserfs_insert_item(th, &path_to_key, &key, &ih, inode,
                                 (char *)(&sd));
        if (retval) {
                err = retval;
                reiserfs_check_path(&path_to_key);
                goto out_bad_inode;
        }
#ifdef DISPLACE_NEW_PACKING_LOCALITIES
        if (!th->displace_new_blocks)
                REISERFS_I(dir)->new_packing_locality = 0;
#endif
        if (S_ISDIR(mode)) {
                /* insert item with "." and ".." */
                retval =
                    reiserfs_new_directory(th, inode, &ih, &path_to_key, dir);
        }

        if (S_ISLNK(mode)) {
                /* insert body of symlink */
                if (!old_format_only(sb))
                        i_size = ROUND_UP(i_size);
                retval =
                    reiserfs_new_symlink(th, inode, &ih, &path_to_key, symname,
                                         i_size);
        }
        if (retval) {
                err = retval;
                reiserfs_check_path(&path_to_key);
                journal_end(th);
                goto out_inserted_sd;
        }

        /*
         * Mark it private if we're creating the privroot
         * or something under it.
         */
        if (IS_PRIVATE(dir) || dentry == REISERFS_SB(sb)->priv_root) {
                inode->i_flags |= S_PRIVATE;
                inode->i_opflags &= ~IOP_XATTR;
        }

        if (reiserfs_posixacl(inode->i_sb)) {
                reiserfs_write_unlock(inode->i_sb);
                retval = reiserfs_inherit_default_acl(th, dir, dentry, inode);
                reiserfs_write_lock(inode->i_sb);
                if (retval) {
                        err = retval;
                        reiserfs_check_path(&path_to_key);
                        journal_end(th);
                        goto out_inserted_sd;
                }
        } else if (inode->i_sb->s_flags & SB_POSIXACL) {
                reiserfs_warning(inode->i_sb, "jdm-13090",
                                 "ACLs aren't enabled in the fs, "
                                 "but vfs thinks they are!");
        }

        if (security->name) {
                reiserfs_write_unlock(inode->i_sb);
                retval = reiserfs_security_write(th, inode, security);
                reiserfs_write_lock(inode->i_sb);
                if (retval) {
                        err = retval;
                        reiserfs_check_path(&path_to_key);
                        retval = journal_end(th);
                        if (retval)
                                err = retval;
                        goto out_inserted_sd;
                }
        }

        reiserfs_update_sd(th, inode);
        reiserfs_check_path(&path_to_key);

        return 0;

out_bad_inode:
        /* Invalidate the object, nothing was inserted yet */
        INODE_PKEY(inode)->k_objectid = 0;

        /* Quota change must be inside a transaction for journaling */
        depth = reiserfs_write_unlock_nested(inode->i_sb);
        dquot_free_inode(inode);
        reiserfs_write_lock_nested(inode->i_sb, depth);

out_end_trans:
        journal_end(th);
        /*
         * Drop can be outside and it needs more credits so it's better
         * to have it outside
         */
        depth = reiserfs_write_unlock_nested(inode->i_sb);
        dquot_drop(inode);
        reiserfs_write_lock_nested(inode->i_sb, depth);
        inode->i_flags |= S_NOQUOTA;
        make_bad_inode(inode);

out_inserted_sd:
        clear_nlink(inode);
        th->t_trans_id = 0;     /* so the caller can't use this handle later */
        if (inode->i_state & I_NEW)
                unlock_new_inode(inode);
        iput(inode);
        return err;
}

/*
 * finds the tail page in the page cache,
 * reads the last block in.
 *
 * On success, page_result is set to a locked, pinned page, and bh_result
 * is set to an up to date buffer for the last block in the file.  returns 0.
 *
 * tail conversion is not done, so bh_result might not be valid for writing
 * check buffer_mapped(bh_result) and bh_result->b_blocknr != 0 before
 * trying to write the block.
 *
 * on failure, nonzero is returned, page_result and bh_result are untouched.
 */
static int grab_tail_page(struct inode *inode,
                          struct page **page_result,
                          struct buffer_head **bh_result)
{

        /*
         * we want the page with the last byte in the file,
         * not the page that will hold the next byte for appending
         */
        unsigned long index = (inode->i_size - 1) >> PAGE_SHIFT;
        unsigned long pos = 0;
        unsigned long start = 0;
        unsigned long blocksize = inode->i_sb->s_blocksize;
        unsigned long offset = (inode->i_size) & (PAGE_SIZE - 1);
        struct buffer_head *bh;
        struct buffer_head *head;
        struct page *page;
        int error;

        /*
         * we know that we are only called with inode->i_size > 0.
         * we also know that a file tail can never be as big as a block
         * If i_size % blocksize == 0, our file is currently block aligned
         * and it won't need converting or zeroing after a truncate.
         */
        if ((offset & (blocksize - 1)) == 0) {
                return -ENOENT;
        }
        page = grab_cache_page(inode->i_mapping, index);
        error = -ENOMEM;
        if (!page) {
                goto out;
        }
        /* start within the page of the last block in the file */
        start = (offset / blocksize) * blocksize;

        error = __block_write_begin(page, start, offset - start,
                                    reiserfs_get_block_create_0);
        if (error)
                goto unlock;

        head = page_buffers(page);
        bh = head;
        do {
                if (pos >= start) {
                        break;
                }
                bh = bh->b_this_page;
                pos += blocksize;
        } while (bh != head);

        if (!buffer_uptodate(bh)) {
                /*
                 * note, this should never happen, prepare_write should be
                 * taking care of this for us.  If the buffer isn't up to
                 * date, I've screwed up the code to find the buffer, or the
                 * code to call prepare_write
                 */
                reiserfs_error(inode->i_sb, "clm-6000",
                               "error reading block %lu", bh->b_blocknr);
                error = -EIO;
                goto unlock;
        }
        *bh_result = bh;
        *page_result = page;

out:
        return error;

unlock:
        unlock_page(page);
        put_page(page);
        return error;
}

/*
 * vfs version of truncate file.  Must NOT be called with
 * a transaction already started.
 *
 * some code taken from block_truncate_page
 */
int reiserfs_truncate_file(struct inode *inode, int update_timestamps)
{
        struct reiserfs_transaction_handle th;
        /* we want the offset for the first byte after the end of the file */
        unsigned long offset = inode->i_size & (PAGE_SIZE - 1);
        unsigned blocksize = inode->i_sb->s_blocksize;
        unsigned length;
        struct page *page = NULL;
        int error;
        struct buffer_head *bh = NULL;
        int err2;

        reiserfs_write_lock(inode->i_sb);

        if (inode->i_size > 0) {
                error = grab_tail_page(inode, &page, &bh);
                if (error) {
                        /*
                         * -ENOENT means we truncated past the end of the
                         * file, and get_block_create_0 could not find a
                         * block to read in, which is ok.
                         */
                        if (error != -ENOENT)
                                reiserfs_error(inode->i_sb, "clm-6001",
                                               "grab_tail_page failed %d",
                                               error);
                        page = NULL;
                        bh = NULL;
                }
        }

        /*
         * so, if page != NULL, we have a buffer head for the offset at
         * the end of the file. if the bh is mapped, and bh->b_blocknr != 0,
         * then we have an unformatted node.  Otherwise, we have a direct item,
         * and no zeroing is required on disk.  We zero after the truncate,
         * because the truncate might pack the item anyway
         * (it will unmap bh if it packs).
         *
         * it is enough to reserve space in transaction for 2 balancings:
         * one for "save" link adding and another for the first
         * cut_from_item. 1 is for update_sd
         */
        error = journal_begin(&th, inode->i_sb,
                              JOURNAL_PER_BALANCE_CNT * 2 + 1);
        if (error)
                goto out;
        reiserfs_update_inode_transaction(inode);
        if (update_timestamps)
                /*
                 * we are doing real truncate: if the system crashes
                 * before the last transaction of truncating gets committed
                 * - on reboot the file either appears truncated properly
                 * or not truncated at all
                 */
                add_save_link(&th, inode, 1);
        err2 = reiserfs_do_truncate(&th, inode, page, update_timestamps);
        error = journal_end(&th);
        if (error)
                goto out;

        /* check reiserfs_do_truncate after ending the transaction */
        if (err2) {
                error = err2;
                goto out;
        }
        
        if (update_timestamps) {
                error = remove_save_link(inode, 1 /* truncate */);
                if (error)
                        goto out;
        }

        if (page) {
                length = offset & (blocksize - 1);
                /* if we are not on a block boundary */
                if (length) {
                        length = blocksize - length;
                        zero_user(page, offset, length);
                        if (buffer_mapped(bh) && bh->b_blocknr != 0) {
                                mark_buffer_dirty(bh);
                        }
                }
                unlock_page(page);
                put_page(page);
        }

        reiserfs_write_unlock(inode->i_sb);

        return 0;
out:
        if (page) {
                unlock_page(page);
                put_page(page);
        }

        reiserfs_write_unlock(inode->i_sb);

        return error;
}

static int map_block_for_writepage(struct inode *inode,
                                   struct buffer_head *bh_result,
                                   unsigned long block)
{
        struct reiserfs_transaction_handle th;
        int fs_gen;
        struct item_head tmp_ih;
        struct item_head *ih;
        struct buffer_head *bh;
        __le32 *item;
        struct cpu_key key;
        INITIALIZE_PATH(path);
        int pos_in_item;
        int jbegin_count = JOURNAL_PER_BALANCE_CNT;
        loff_t byte_offset = ((loff_t)block << inode->i_sb->s_blocksize_bits)+1;
        int retval;
        int use_get_block = 0;
        int bytes_copied = 0;
        int copy_size;
        int trans_running = 0;

        /*
         * catch places below that try to log something without
         * starting a trans
         */
        th.t_trans_id = 0;

        if (!buffer_uptodate(bh_result)) {
                return -EIO;
        }

        kmap(bh_result->b_page);
start_over:
        reiserfs_write_lock(inode->i_sb);
        make_cpu_key(&key, inode, byte_offset, TYPE_ANY, 3);

research:
        retval = search_for_position_by_key(inode->i_sb, &key, &path);
        if (retval != POSITION_FOUND) {
                use_get_block = 1;
                goto out;
        }

        bh = get_last_bh(&path);
        ih = tp_item_head(&path);
        item = tp_item_body(&path);
        pos_in_item = path.pos_in_item;

        /* we've found an unformatted node */
        if (indirect_item_found(retval, ih)) {
                if (bytes_copied > 0) {
                        reiserfs_warning(inode->i_sb, "clm-6002",
                                         "bytes_copied %d", bytes_copied);
                }
                if (!get_block_num(item, pos_in_item)) {
                        /* crap, we are writing to a hole */
                        use_get_block = 1;
                        goto out;
                }
                set_block_dev_mapped(bh_result,
                                     get_block_num(item, pos_in_item), inode);
        } else if (is_direct_le_ih(ih)) {
                char *p;
                p = page_address(bh_result->b_page);
                p += (byte_offset - 1) & (PAGE_SIZE - 1);
                copy_size = ih_item_len(ih) - pos_in_item;

                fs_gen = get_generation(inode->i_sb);
                copy_item_head(&tmp_ih, ih);

                if (!trans_running) {
                        /* vs-3050 is gone, no need to drop the path */
                        retval = journal_begin(&th, inode->i_sb, jbegin_count);
                        if (retval)
                                goto out;
                        reiserfs_update_inode_transaction(inode);
                        trans_running = 1;
                        if (fs_changed(fs_gen, inode->i_sb)
                            && item_moved(&tmp_ih, &path)) {
                                reiserfs_restore_prepared_buffer(inode->i_sb,
                                                                 bh);
                                goto research;
                        }
                }

                reiserfs_prepare_for_journal(inode->i_sb, bh, 1);

                if (fs_changed(fs_gen, inode->i_sb)
                    && item_moved(&tmp_ih, &path)) {
                        reiserfs_restore_prepared_buffer(inode->i_sb, bh);
                        goto research;
                }

                memcpy(ih_item_body(bh, ih) + pos_in_item, p + bytes_copied,
                       copy_size);

                journal_mark_dirty(&th, bh);
                bytes_copied += copy_size;
                set_block_dev_mapped(bh_result, 0, inode);

                /* are there still bytes left? */
                if (bytes_copied < bh_result->b_size &&
                    (byte_offset + bytes_copied) < inode->i_size) {
                        set_cpu_key_k_offset(&key,
                                             cpu_key_k_offset(&key) +
                                             copy_size);
                        goto research;
                }
        } else {
                reiserfs_warning(inode->i_sb, "clm-6003",
                                 "bad item inode %lu", inode->i_ino);
                retval = -EIO;
                goto out;
        }
        retval = 0;

out:
        pathrelse(&path);
        if (trans_running) {
                int err = journal_end(&th);
                if (err)
                        retval = err;
                trans_running = 0;
        }
        reiserfs_write_unlock(inode->i_sb);

        /* this is where we fill in holes in the file. */
        if (use_get_block) {
                retval = reiserfs_get_block(inode, block, bh_result,
                                            GET_BLOCK_CREATE | GET_BLOCK_NO_IMUX
                                            | GET_BLOCK_NO_DANGLE);
                if (!retval) {
                        if (!buffer_mapped(bh_result)
                            || bh_result->b_blocknr == 0) {
                                /* get_block failed to find a mapped unformatted node. */
                                use_get_block = 0;
                                goto start_over;
                        }
                }
        }
        kunmap(bh_result->b_page);

        if (!retval && buffer_mapped(bh_result) && bh_result->b_blocknr == 0) {
                /*
                 * we've copied data from the page into the direct item, so the
                 * buffer in the page is now clean, mark it to reflect that.
                 */
                lock_buffer(bh_result);
                clear_buffer_dirty(bh_result);
                unlock_buffer(bh_result);
        }
        return retval;
}

/*
 * mason@suse.com: updated in 2.5.54 to follow the same general io
 * start/recovery path as __block_write_full_page, along with special
 * code to handle reiserfs tails.
 */
static int reiserfs_write_full_page(struct page *page,
                                    struct writeback_control *wbc)
{
        struct inode *inode = page->mapping->host;
        unsigned long end_index = inode->i_size >> PAGE_SHIFT;
        int error = 0;
        unsigned long block;
        sector_t last_block;
        struct buffer_head *head, *bh;
        int partial = 0;
        int nr = 0;
        int checked = PageChecked(page);
        struct reiserfs_transaction_handle th;
        struct super_block *s = inode->i_sb;
        int bh_per_page = PAGE_SIZE / s->s_blocksize;
        th.t_trans_id = 0;

        /* no logging allowed when nonblocking or from PF_MEMALLOC */
        if (checked && (current->flags & PF_MEMALLOC)) {
                redirty_page_for_writepage(wbc, page);
                unlock_page(page);
                return 0;
        }

        /*
         * The page dirty bit is cleared before writepage is called, which
         * means we have to tell create_empty_buffers to make dirty buffers
         * The page really should be up to date at this point, so tossing
         * in the BH_Uptodate is just a sanity check.
         */
        if (!page_has_buffers(page)) {
                create_empty_buffers(page, s->s_blocksize,
                                     (1 << BH_Dirty) | (1 << BH_Uptodate));
        }
        head = page_buffers(page);

        /*
         * last page in the file, zero out any contents past the
         * last byte in the file
         */
        if (page->index >= end_index) {
                unsigned last_offset;

                last_offset = inode->i_size & (PAGE_SIZE - 1);
                /* no file contents in this page */
                if (page->index >= end_index + 1 || !last_offset) {
                        unlock_page(page);
                        return 0;
                }
                zero_user_segment(page, last_offset, PAGE_SIZE);
        }
        bh = head;
        block = page->index << (PAGE_SHIFT - s->s_blocksize_bits);
        last_block = (i_size_read(inode) - 1) >> inode->i_blkbits;
        /* first map all the buffers, logging any direct items we find */
        do {
                if (block > last_block) {
                        /*
                         * This can happen when the block size is less than
                         * the page size.  The corresponding bytes in the page
                         * were zero filled above
                         */
                        clear_buffer_dirty(bh);
                        set_buffer_uptodate(bh);
                } else if ((checked || buffer_dirty(bh)) &&
                           (!buffer_mapped(bh) || bh->b_blocknr == 0)) {
                        /*
                         * not mapped yet, or it points to a direct item, search
                         * the btree for the mapping info, and log any direct
                         * items found
                         */
                        if ((error = map_block_for_writepage(inode, bh, block))) {
                                goto fail;
                        }
                }
                bh = bh->b_this_page;
                block++;
        } while (bh != head);

        /*
         * we start the transaction after map_block_for_writepage,
         * because it can create holes in the file (an unbounded operation).
         * starting it here, we can make a reliable estimate for how many
         * blocks we're going to log
         */
        if (checked) {
                ClearPageChecked(page);
                reiserfs_write_lock(s);
                error = journal_begin(&th, s, bh_per_page + 1);
                if (error) {
                        reiserfs_write_unlock(s);
                        goto fail;
                }
                reiserfs_update_inode_transaction(inode);
        }
        /* now go through and lock any dirty buffers on the page */
        do {
                get_bh(bh);
                if (!buffer_mapped(bh))
                        continue;
                if (buffer_mapped(bh) && bh->b_blocknr == 0)
                        continue;

                if (checked) {
                        reiserfs_prepare_for_journal(s, bh, 1);
                        journal_mark_dirty(&th, bh);
                        continue;
                }
                /*
                 * from this point on, we know the buffer is mapped to a
                 * real block and not a direct item
                 */
                if (wbc->sync_mode != WB_SYNC_NONE) {
                        lock_buffer(bh);
                } else {
                        if (!trylock_buffer(bh)) {
                                redirty_page_for_writepage(wbc, page);
                                continue;
                        }
                }
                if (test_clear_buffer_dirty(bh)) {
                        mark_buffer_async_write(bh);
                } else {
                        unlock_buffer(bh);
                }
        } while ((bh = bh->b_this_page) != head);

        if (checked) {
                error = journal_end(&th);
                reiserfs_write_unlock(s);
                if (error)
                        goto fail;
        }
        BUG_ON(PageWriteback(page));
        set_page_writeback(page);
        unlock_page(page);

        /*
         * since any buffer might be the only dirty buffer on the page,
         * the first submit_bh can bring the page out of writeback.
         * be careful with the buffers.
         */
        do {
                struct buffer_head *next = bh->b_this_page;
                if (buffer_async_write(bh)) {
                        submit_bh(REQ_OP_WRITE, 0, bh);
                        nr++;
                }
                put_bh(bh);
                bh = next;
        } while (bh != head);

        error = 0;
done:
        if (nr == 0) {
                /*
                 * if this page only had a direct item, it is very possible for
                 * no io to be required without there being an error.  Or,
                 * someone else could have locked them and sent them down the
                 * pipe without locking the page
                 */
                bh = head;
                do {
                        if (!buffer_uptodate(bh)) {
                                partial = 1;
                                break;
                        }
                        bh = bh->b_this_page;
                } while (bh != head);
                if (!partial)
                        SetPageUptodate(page);
                end_page_writeback(page);
        }
        return error;

fail:
        /*
         * catches various errors, we need to make sure any valid dirty blocks
         * get to the media.  The page is currently locked and not marked for
         * writeback
         */
        ClearPageUptodate(page);
        bh = head;
        do {
                get_bh(bh);
                if (buffer_mapped(bh) && buffer_dirty(bh) && bh->b_blocknr) {
                        lock_buffer(bh);
                        mark_buffer_async_write(bh);
                } else {
                        /*
                         * clear any dirty bits that might have come from
                         * getting attached to a dirty page
                         */
                        clear_buffer_dirty(bh);
                }
                bh = bh->b_this_page;
        } while (bh != head);
        SetPageError(page);
        BUG_ON(PageWriteback(page));
        set_page_writeback(page);
        unlock_page(page);
        do {
                struct buffer_head *next = bh->b_this_page;
                if (buffer_async_write(bh)) {
                        clear_buffer_dirty(bh);
                        submit_bh(REQ_OP_WRITE, 0, bh);
                        nr++;
                }
                put_bh(bh);
                bh = next;
        } while (bh != head);
        goto done;
}

static int reiserfs_readpage(struct file *f, struct page *page)
{
        return block_read_full_page(page, reiserfs_get_block);
}

static int reiserfs_writepage(struct page *page, struct writeback_control *wbc)
{
        struct inode *inode = page->mapping->host;
        reiserfs_wait_on_write_block(inode->i_sb);
        return reiserfs_write_full_page(page, wbc);
}

static void reiserfs_truncate_failed_write(struct inode *inode)
{
        truncate_inode_pages(inode->i_mapping, inode->i_size);
        reiserfs_truncate_file(inode, 0);
}

static int reiserfs_write_begin(struct file *file,
                                struct address_space *mapping,
                                loff_t pos, unsigned len, unsigned flags,
                                struct page **pagep, void **fsdata)
{
        struct inode *inode;
        struct page *page;
        pgoff_t index;
        int ret;
        int old_ref = 0;

        inode = mapping->host;
        *fsdata = NULL;
        if (flags & AOP_FLAG_CONT_EXPAND &&
            (pos & (inode->i_sb->s_blocksize - 1)) == 0) {
                pos ++;
                *fsdata = (void *)(unsigned long)flags;
        }

        index = pos >> PAGE_SHIFT;
        page = grab_cache_page_write_begin(mapping, index, flags);
        if (!page)
                return -ENOMEM;
        *pagep = page;

        reiserfs_wait_on_write_block(inode->i_sb);
        fix_tail_page_for_writing(page);
        if (reiserfs_transaction_running(inode->i_sb)) {
                struct reiserfs_transaction_handle *th;
                th = (struct reiserfs_transaction_handle *)current->
                    journal_info;
                BUG_ON(!th->t_refcount);
                BUG_ON(!th->t_trans_id);
                old_ref = th->t_refcount;
                th->t_refcount++;
        }
        ret = __block_write_begin(page, pos, len, reiserfs_get_block);
        if (ret && reiserfs_transaction_running(inode->i_sb)) {
                struct reiserfs_transaction_handle *th = current->journal_info;
                /*
                 * this gets a little ugly.  If reiserfs_get_block returned an
                 * error and left a transacstion running, we've got to close
                 * it, and we've got to free handle if it was a persistent
                 * transaction.
                 *
                 * But, if we had nested into an existing transaction, we need
                 * to just drop the ref count on the handle.
                 *
                 * If old_ref == 0, the transaction is from reiserfs_get_block,
                 * and it was a persistent trans.  Otherwise, it was nested
                 * above.
                 */
                if (th->t_refcount > old_ref) {
                        if (old_ref)
                                th->t_refcount--;
                        else {
                                int err;
                                reiserfs_write_lock(inode->i_sb);
                                err = reiserfs_end_persistent_transaction(th);
                                reiserfs_write_unlock(inode->i_sb);
                                if (err)
                                        ret = err;
                        }
                }
        }
        if (ret) {
                unlock_page(page);
                put_page(page);
                /* Truncate allocated blocks */
                reiserfs_truncate_failed_write(inode);
        }
        return ret;
}

int __reiserfs_write_begin(struct page *page, unsigned from, unsigned len)
{
        struct inode *inode = page->mapping->host;
        int ret;
        int old_ref = 0;
        int depth;

        depth = reiserfs_write_unlock_nested(inode->i_sb);
        reiserfs_wait_on_write_block(inode->i_sb);
        reiserfs_write_lock_nested(inode->i_sb, depth);

        fix_tail_page_for_writing(page);
        if (reiserfs_transaction_running(inode->i_sb)) {
                struct reiserfs_transaction_handle *th;
                th = (struct reiserfs_transaction_handle *)current->
                    journal_info;
                BUG_ON(!th->t_refcount);
                BUG_ON(!th->t_trans_id);
                old_ref = th->t_refcount;
                th->t_refcount++;
        }

        ret = __block_write_begin(page, from, len, reiserfs_get_block);
        if (ret && reiserfs_transaction_running(inode->i_sb)) {
                struct reiserfs_transaction_handle *th = current->journal_info;
                /*
                 * this gets a little ugly.  If reiserfs_get_block returned an
                 * error and left a transacstion running, we've got to close
                 * it, and we've got to free handle if it was a persistent
                 * transaction.
                 *
                 * But, if we had nested into an existing transaction, we need
                 * to just drop the ref count on the handle.
                 *
                 * If old_ref == 0, the transaction is from reiserfs_get_block,
                 * and it was a persistent trans.  Otherwise, it was nested
                 * above.
                 */
                if (th->t_refcount > old_ref) {
                        if (old_ref)
                                th->t_refcount--;
                        else {
                                int err;
                                reiserfs_write_lock(inode->i_sb);
                                err = reiserfs_end_persistent_transaction(th);
                                reiserfs_write_unlock(inode->i_sb);
                                if (err)
                                        ret = err;
                        }
                }
        }
        return ret;

}

static sector_t reiserfs_aop_bmap(struct address_space *as, sector_t block)
{
        return generic_block_bmap(as, block, reiserfs_bmap);
}

static int reiserfs_write_end(struct file *file, struct address_space *mapping,
                              loff_t pos, unsigned len, unsigned copied,
                              struct page *page, void *fsdata)
{
        struct inode *inode = page->mapping->host;
        int ret = 0;
        int update_sd = 0;
        struct reiserfs_transaction_handle *th;
        unsigned start;
        bool locked = false;

        if ((unsigned long)fsdata & AOP_FLAG_CONT_EXPAND)
                pos ++;

        reiserfs_wait_on_write_block(inode->i_sb);
        if (reiserfs_transaction_running(inode->i_sb))
                th = current->journal_info;
        else
                th = NULL;

        start = pos & (PAGE_SIZE - 1);
        if (unlikely(copied < len)) {
                if (!PageUptodate(page))
                        copied = 0;

                page_zero_new_buffers(page, start + copied, start + len);
        }
        flush_dcache_page(page);

        reiserfs_commit_page(inode, page, start, start + copied);

        /*
         * generic_commit_write does this for us, but does not update the
         * transaction tracking stuff when the size changes.  So, we have
         * to do the i_size updates here.
         */
        if (pos + copied > inode->i_size) {
                struct reiserfs_transaction_handle myth;
                reiserfs_write_lock(inode->i_sb);
                locked = true;
                /*
                 * If the file have grown beyond the border where it
                 * can have a tail, unmark it as needing a tail
                 * packing
                 */
                if ((have_large_tails(inode->i_sb)
                     && inode->i_size > i_block_size(inode) * 4)
                    || (have_small_tails(inode->i_sb)
                        && inode->i_size > i_block_size(inode)))
                        REISERFS_I(inode)->i_flags &= ~i_pack_on_close_mask;

                ret = journal_begin(&myth, inode->i_sb, 1);
                if (ret)
                        goto journal_error;

                reiserfs_update_inode_transaction(inode);
                inode->i_size = pos + copied;
                /*
                 * this will just nest into our transaction.  It's important
                 * to use mark_inode_dirty so the inode gets pushed around on
                 * the dirty lists, and so that O_SYNC works as expected
                 */
                mark_inode_dirty(inode);
                reiserfs_update_sd(&myth, inode);
                update_sd = 1;
                ret = journal_end(&myth);
                if (ret)
                        goto journal_error;
        }
        if (th) {
                if (!locked) {
                        reiserfs_write_lock(inode->i_sb);
                        locked = true;
                }
                if (!update_sd)
                        mark_inode_dirty(inode);
                ret = reiserfs_end_persistent_transaction(th);
                if (ret)
                        goto out;
        }

out:
        if (locked)
                reiserfs_write_unlock(inode->i_sb);
        unlock_page(page);
        put_page(page);

        if (pos + len > inode->i_size)
                reiserfs_truncate_failed_write(inode);

        return ret == 0 ? copied : ret;

journal_error:
        reiserfs_write_unlock(inode->i_sb);
        locked = false;
        if (th) {
                if (!update_sd)
                        reiserfs_update_sd(th, inode);
                ret = reiserfs_end_persistent_transaction(th);
        }
        goto out;
}

int reiserfs_commit_write(struct file *f, struct page *page,
                          unsigned from, unsigned to)
{
        struct inode *inode = page->mapping->host;
        loff_t pos = ((loff_t) page->index << PAGE_SHIFT) + to;
        int ret = 0;
        int update_sd = 0;
        struct reiserfs_transaction_handle *th = NULL;
        int depth;