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

#include <linux/time.h>
#include "reiserfs.h"
#include "acl.h"
#include "xattr.h"
#include <linux/uaccess.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
#include <linux/writeback.h>
#include <linux/blkdev.h>
#include <linux/buffer_head.h>
#include <linux/quotaops.h>

/*
 * We pack the tails of files on file close, not at the time they are written.
 * This implies an unnecessary copy of the tail and an unnecessary indirect item
 * insertion/balancing, for files that are written in one write.
 * It avoids unnecessary tail packings (balances) for files that are written in
 * multiple writes and are small enough to have tails.
 *
 * file_release is called by the VFS layer when the file is closed.  If
 * this is the last open file descriptor, and the file
 * small enough to have a tail, and the tail is currently in an
 * unformatted node, the tail is converted back into a direct item.
 *
 * We use reiserfs_truncate_file to pack the tail, since it already has
 * all the conditions coded.
 */
static int reiserfs_file_release(struct inode *inode, struct file *filp)
{

        struct reiserfs_transaction_handle th;
        int err;
        int jbegin_failure = 0;

        BUG_ON(!S_ISREG(inode->i_mode));

        if (atomic_add_unless(&REISERFS_I(inode)->openers, -1, 1))
                return 0;

        mutex_lock(&REISERFS_I(inode)->tailpack);

        if (!atomic_dec_and_test(&REISERFS_I(inode)->openers)) {
                mutex_unlock(&REISERFS_I(inode)->tailpack);
                return 0;
        }

        /* fast out for when nothing needs to be done */
        if ((!(REISERFS_I(inode)->i_flags & i_pack_on_close_mask) ||
             !tail_has_to_be_packed(inode)) &&
            REISERFS_I(inode)->i_prealloc_count <= 0) {
                mutex_unlock(&REISERFS_I(inode)->tailpack);
                return 0;
        }

        reiserfs_write_lock(inode->i_sb);
        /*
         * freeing preallocation only involves relogging blocks that
         * are already in the current transaction.  preallocation gets
         * freed at the end of each transaction, so it is impossible for
         * us to log any additional blocks (including quota blocks)
         */
        err = journal_begin(&th, inode->i_sb, 1);
        if (err) {
                /*
                 * uh oh, we can't allow the inode to go away while there
                 * is still preallocation blocks pending.  Try to join the
                 * aborted transaction
                 */
                jbegin_failure = err;
                err = journal_join_abort(&th, inode->i_sb);

                if (err) {
                        /*
                         * hmpf, our choices here aren't good.  We can pin
                         * the inode which will disallow unmount from ever
                         * happening, we can do nothing, which will corrupt
                         * random memory on unmount, or we can forcibly
                         * remove the file from the preallocation list, which
                         * will leak blocks on disk.  Lets pin the inode
                         * and let the admin know what is going on.
                         */
                        igrab(inode);
                        reiserfs_warning(inode->i_sb, "clm-9001",
                                         "pinning inode %lu because the "
                                         "preallocation can't be freed",
                                         inode->i_ino);
                        goto out;
                }
        }
        reiserfs_update_inode_transaction(inode);

#ifdef REISERFS_PREALLOCATE
        reiserfs_discard_prealloc(&th, inode);
#endif
        err = journal_end(&th);

        /* copy back the error code from journal_begin */
        if (!err)
                err = jbegin_failure;

        if (!err &&
            (REISERFS_I(inode)->i_flags & i_pack_on_close_mask) &&
            tail_has_to_be_packed(inode)) {

                /*
                 * if regular file is released by last holder and it has been
                 * appended (we append by unformatted node only) or its direct
                 * item(s) had to be converted, then it may have to be
                 * indirect2direct converted
                 */
                err = reiserfs_truncate_file(inode, 0);
        }
out:
        reiserfs_write_unlock(inode->i_sb);
        mutex_unlock(&REISERFS_I(inode)->tailpack);
        return err;
}

static int reiserfs_file_open(struct inode *inode, struct file *file)
{
        int err = dquot_file_open(inode, file);

        /* somebody might be tailpacking on final close; wait for it */
        if (!atomic_inc_not_zero(&REISERFS_I(inode)->openers)) {
                mutex_lock(&REISERFS_I(inode)->tailpack);
                atomic_inc(&REISERFS_I(inode)->openers);
                mutex_unlock(&REISERFS_I(inode)->tailpack);
        }
        return err;
}

void reiserfs_vfs_truncate_file(struct inode *inode)
{
        mutex_lock(&REISERFS_I(inode)->tailpack);
        reiserfs_truncate_file(inode, 1);
        mutex_unlock(&REISERFS_I(inode)->tailpack);
}

/* Sync a reiserfs file. */

/*
 * FIXME: sync_mapping_buffers() never has anything to sync.  Can
 * be removed...
 */

static int reiserfs_sync_file(struct file *filp, loff_t start, loff_t end,
                              int datasync)
{
        struct inode *inode = filp->f_mapping->host;
        int err;
        int barrier_done;

        err = file_write_and_wait_range(filp, start, end);
        if (err)
                return err;

        inode_lock(inode);
        BUG_ON(!S_ISREG(inode->i_mode));
        err = sync_mapping_buffers(inode->i_mapping);
        reiserfs_write_lock(inode->i_sb);
        barrier_done = reiserfs_commit_for_inode(inode);
        reiserfs_write_unlock(inode->i_sb);
        if (barrier_done != 1 && reiserfs_barrier_flush(inode->i_sb))
                blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL);
        inode_unlock(inode);
        if (barrier_done < 0)
                return barrier_done;
        return (err < 0) ? -EIO : 0;
}

/* taken fs/buffer.c:__block_commit_write */
int reiserfs_commit_page(struct inode *inode, struct page *page,
                         unsigned from, unsigned to)
{
        unsigned block_start, block_end;
        int partial = 0;
        unsigned blocksize;
        struct buffer_head *bh, *head;
        unsigned long i_size_index = inode->i_size >> PAGE_SHIFT;
        int new;
        int logit = reiserfs_file_data_log(inode);
        struct super_block *s = inode->i_sb;
        int bh_per_page = PAGE_SIZE / s->s_blocksize;
        struct reiserfs_transaction_handle th;
        int ret = 0;

        th.t_trans_id = 0;
        blocksize = i_blocksize(inode);

        if (logit) {
                reiserfs_write_lock(s);
                ret = journal_begin(&th, s, bh_per_page + 1);
                if (ret)
                        goto drop_write_lock;
                reiserfs_update_inode_transaction(inode);
        }
        for (bh = head = page_buffers(page), block_start = 0;
             bh != head || !block_start;
             block_start = block_end, bh = bh->b_this_page) {

                new = buffer_new(bh);
                clear_buffer_new(bh);
                block_end = block_start + blocksize;
                if (block_end <= from || block_start >= to) {
                        if (!buffer_uptodate(bh))
                                partial = 1;
                } else {
                        set_buffer_uptodate(bh);
                        if (logit) {
                                reiserfs_prepare_for_journal(s, bh, 1);
                                journal_mark_dirty(&th, bh);
                        } else if (!buffer_dirty(bh)) {
                                mark_buffer_dirty(bh);
                                /*
                                 * do data=ordered on any page past the end
                                 * of file and any buffer marked BH_New.
                                 */
                                if (reiserfs_data_ordered(inode->i_sb) &&
                                    (new || page->index >= i_size_index)) {
                                        reiserfs_add_ordered_list(inode, bh);
                                }
                        }
                }
        }
        if (logit) {
                ret = journal_end(&th);
drop_write_lock:
                reiserfs_write_unlock(s);
        }
        /*
         * If this is a partial write which happened to make all buffers
         * uptodate then we can optimize away a bogus readpage() for
         * the next read(). Here we 'discover' whether the page went
         * uptodate as a result of this (potentially partial) write.
         */
        if (!partial)
                SetPageUptodate(page);
        return ret;
}

const struct file_operations reiserfs_file_operations = {
        .unlocked_ioctl = reiserfs_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl = reiserfs_compat_ioctl,
#endif
        .mmap = generic_file_mmap,
        .open = reiserfs_file_open,
        .release = reiserfs_file_release,
        .fsync = reiserfs_sync_file,
        .read_iter = generic_file_read_iter,
        .write_iter = generic_file_write_iter,
        .splice_read = generic_file_splice_read,
        .splice_write = iter_file_splice_write,
        .llseek = generic_file_llseek,
};

const struct inode_operations reiserfs_file_inode_operations = {
        .setattr = reiserfs_setattr,
        .listxattr = reiserfs_listxattr,
        .permission = reiserfs_permission,
        .get_acl = reiserfs_get_acl,
        .set_acl = reiserfs_set_acl,
};