/*
 * Copyright 1999 Hans Reiser, see reiserfs/README for licensing and copyright
 * details
 */

#include <linux/time.h>
#include <linux/pagemap.h>
#include <linux/buffer_head.h>
#include "reiserfs.h"

/*
 * access to tail : when one is going to read tail it must make sure, that is
 * not running.  direct2indirect and indirect2direct can not run concurrently
 */

/*
 * Converts direct items to an unformatted node. Panics if file has no
 * tail. -ENOSPC if no disk space for conversion
 */
/*
 * path points to first direct item of the file regardless of how many of
 * them are there
 */
int direct2indirect(struct reiserfs_transaction_handle *th, struct inode *inode,
                    struct treepath *path, struct buffer_head *unbh,
                    loff_t tail_offset)
{
        struct super_block *sb = inode->i_sb;
        struct buffer_head *up_to_date_bh;
        struct item_head *p_le_ih = tp_item_head(path);
        unsigned long total_tail = 0;

        /* Key to search for the last byte of the converted item. */
        struct cpu_key end_key;

        /*
         * new indirect item to be inserted or key
         * of unfm pointer to be pasted
         */
        struct item_head ind_ih;
        int blk_size;
        /* returned value for reiserfs_insert_item and clones */
        int  retval;
        /* Handle on an unformatted node that will be inserted in the tree. */
        unp_t unfm_ptr;

        BUG_ON(!th->t_trans_id);

        REISERFS_SB(sb)->s_direct2indirect++;

        blk_size = sb->s_blocksize;

        /*
         * and key to search for append or insert pointer to the new
         * unformatted node.
         */
        copy_item_head(&ind_ih, p_le_ih);
        set_le_ih_k_offset(&ind_ih, tail_offset);
        set_le_ih_k_type(&ind_ih, TYPE_INDIRECT);

        /* Set the key to search for the place for new unfm pointer */
        make_cpu_key(&end_key, inode, tail_offset, TYPE_INDIRECT, 4);

        /* FIXME: we could avoid this */
        if (search_for_position_by_key(sb, &end_key, path) == POSITION_FOUND) {
                reiserfs_error(sb, "PAP-14030",
                               "pasted or inserted byte exists in "
                               "the tree %K. Use fsck to repair.", &end_key);
                pathrelse(path);
                return -EIO;
        }

        p_le_ih = tp_item_head(path);

        unfm_ptr = cpu_to_le32(unbh->b_blocknr);

        if (is_statdata_le_ih(p_le_ih)) {
                /* Insert new indirect item. */
                set_ih_free_space(&ind_ih, 0);  /* delete at nearest future */
                put_ih_item_len(&ind_ih, UNFM_P_SIZE);
                PATH_LAST_POSITION(path)++;
                retval =
                    reiserfs_insert_item(th, path, &end_key, &ind_ih, inode,
                                         (char *)&unfm_ptr);
        } else {
                /* Paste into last indirect item of an object. */
                retval = reiserfs_paste_into_item(th, path, &end_key, inode,
                                                    (char *)&unfm_ptr,
                                                    UNFM_P_SIZE);
        }
        if (retval) {
                return retval;
        }
        /*
         * note: from here there are two keys which have matching first
         *  three key components. They only differ by the fourth one.
         */

        /* Set the key to search for the direct items of the file */
        make_cpu_key(&end_key, inode, max_reiserfs_offset(inode), TYPE_DIRECT,
                     4);

        /*
         * Move bytes from the direct items to the new unformatted node
         * and delete them.
         */
        while (1) {
                int tail_size;

                /*
                 * end_key.k_offset is set so, that we will always have found
                 * last item of the file
                 */
                if (search_for_position_by_key(sb, &end_key, path) ==
                    POSITION_FOUND)
                        reiserfs_panic(sb, "PAP-14050",
                                       "direct item (%K) not found", &end_key);
                p_le_ih = tp_item_head(path);
                RFALSE(!is_direct_le_ih(p_le_ih),
                       "vs-14055: direct item expected(%K), found %h",
                       &end_key, p_le_ih);
                tail_size = (le_ih_k_offset(p_le_ih) & (blk_size - 1))
                    + ih_item_len(p_le_ih) - 1;

                /*
                 * we only send the unbh pointer if the buffer is not
                 * up to date.  this avoids overwriting good data from
                 * writepage() with old data from the disk or buffer cache
                 * Special case: unbh->b_page will be NULL if we are coming
                 * through DIRECT_IO handler here.
                 */
                if (!unbh->b_page || buffer_uptodate(unbh)
                    || PageUptodate(unbh->b_page)) {
                        up_to_date_bh = NULL;
                } else {
                        up_to_date_bh = unbh;
                }
                retval = reiserfs_delete_item(th, path, &end_key, inode,
                                                up_to_date_bh);

                total_tail += retval;

                /* done: file does not have direct items anymore */
                if (tail_size == retval)
                        break;

        }
        /*
         * if we've copied bytes from disk into the page, we need to zero
         * out the unused part of the block (it was not up to date before)
         */
        if (up_to_date_bh) {
                unsigned pgoff =
                    (tail_offset + total_tail - 1) & (PAGE_SIZE - 1);
                char *kaddr = kmap_atomic(up_to_date_bh->b_page);
                memset(kaddr + pgoff, 0, blk_size - total_tail);
                kunmap_atomic(kaddr);
        }

        REISERFS_I(inode)->i_first_direct_byte = U32_MAX;

        return 0;
}

/* stolen from fs/buffer.c */
void reiserfs_unmap_buffer(struct buffer_head *bh)
{
        lock_buffer(bh);
        if (buffer_journaled(bh) || buffer_journal_dirty(bh)) {
                BUG();
        }
        clear_buffer_dirty(bh);
        /*
         * Remove the buffer from whatever list it belongs to. We are mostly
         * interested in removing it from per-sb j_dirty_buffers list, to avoid
         * BUG() on attempt to write not mapped buffer
         */
        if ((!list_empty(&bh->b_assoc_buffers) || bh->b_private) && bh->b_page) {
                struct inode *inode = bh->b_page->mapping->host;
                struct reiserfs_journal *j = SB_JOURNAL(inode->i_sb);
                spin_lock(&j->j_dirty_buffers_lock);
                list_del_init(&bh->b_assoc_buffers);
                reiserfs_free_jh(bh);
                spin_unlock(&j->j_dirty_buffers_lock);
        }
        clear_buffer_mapped(bh);
        clear_buffer_req(bh);
        clear_buffer_new(bh);
        bh->b_bdev = NULL;
        unlock_buffer(bh);
}

/*
 * this first locks inode (neither reads nor sync are permitted),
 * reads tail through page cache, insert direct item. When direct item
 * inserted successfully inode is left locked. Return value is always
 * what we expect from it (number of cut bytes). But when tail remains
 * in the unformatted node, we set mode to SKIP_BALANCING and unlock
 * inode
 */
int indirect2direct(struct reiserfs_transaction_handle *th,
                    struct inode *inode, struct page *page,
                    struct treepath *path,      /* path to the indirect item. */
                    const struct cpu_key *item_key,     /* Key to look for
                                                         * unformatted node
                                                         * pointer to be cut. */
                    loff_t n_new_file_size,     /* New file size. */
                    char *mode)
{
        struct super_block *sb = inode->i_sb;
        struct item_head s_ih;
        unsigned long block_size = sb->s_blocksize;
        char *tail;
        int tail_len, round_tail_len;
        loff_t pos, pos1;       /* position of first byte of the tail */
        struct cpu_key key;

        BUG_ON(!th->t_trans_id);

        REISERFS_SB(sb)->s_indirect2direct++;

        *mode = M_SKIP_BALANCING;

        /* store item head path points to. */
        copy_item_head(&s_ih, tp_item_head(path));

        tail_len = (n_new_file_size & (block_size - 1));
        if (get_inode_sd_version(inode) == STAT_DATA_V2)
                round_tail_len = ROUND_UP(tail_len);
        else
                round_tail_len = tail_len;

        pos =
            le_ih_k_offset(&s_ih) - 1 + (ih_item_len(&s_ih) / UNFM_P_SIZE -
                                         1) * sb->s_blocksize;
        pos1 = pos;

        /*
         * we are protected by i_mutex. The tail can not disapper, not
         * append can be done either
         * we are in truncate or packing tail in file_release
         */

        tail = (char *)kmap(page);      /* this can schedule */

        if (path_changed(&s_ih, path)) {
                /* re-search indirect item */
                if (search_for_position_by_key(sb, item_key, path)
                    == POSITION_NOT_FOUND)
                        reiserfs_panic(sb, "PAP-5520",
                                       "item to be converted %K does not exist",
                                       item_key);
                copy_item_head(&s_ih, tp_item_head(path));
#ifdef CONFIG_REISERFS_CHECK
                pos = le_ih_k_offset(&s_ih) - 1 +
                    (ih_item_len(&s_ih) / UNFM_P_SIZE -
                     1) * sb->s_blocksize;
                if (pos != pos1)
                        reiserfs_panic(sb, "vs-5530", "tail position "
                                       "changed while we were reading it");
#endif
        }

        /* Set direct item header to insert. */
        make_le_item_head(&s_ih, NULL, get_inode_item_key_version(inode),
                          pos1 + 1, TYPE_DIRECT, round_tail_len,
                          0xffff /*ih_free_space */ );

        /*
         * we want a pointer to the first byte of the tail in the page.
         * the page was locked and this part of the page was up to date when
         * indirect2direct was called, so we know the bytes are still valid
         */
        tail = tail + (pos & (PAGE_SIZE - 1));

        PATH_LAST_POSITION(path)++;

        key = *item_key;
        set_cpu_key_k_type(&key, TYPE_DIRECT);
        key.key_length = 4;
        /* Insert tail as new direct item in the tree */
        if (reiserfs_insert_item(th, path, &key, &s_ih, inode,
                                 tail ? tail : NULL) < 0) {
                /*
                 * No disk memory. So we can not convert last unformatted node
                 * to the direct item.  In this case we used to adjust
                 * indirect items's ih_free_space. Now ih_free_space is not
                 * used, it would be ideal to write zeros to corresponding
                 * unformatted node. For now i_size is considered as guard for
                 * going out of file size
                 */
                kunmap(page);
                return block_size - round_tail_len;
        }
        kunmap(page);

        /* make sure to get the i_blocks changes from reiserfs_insert_item */
        reiserfs_update_sd(th, inode);

        /*
         * note: we have now the same as in above direct2indirect
         * conversion: there are two keys which have matching first three
         * key components. They only differ by the fourth one.
         */

        /*
         * We have inserted new direct item and must remove last
         * unformatted node.
         */
        *mode = M_CUT;

        /* we store position of first direct item in the in-core inode */
        /* mark_file_with_tail (inode, pos1 + 1); */
        REISERFS_I(inode)->i_first_direct_byte = pos1 + 1;

        return block_size - round_tail_len;
}