ext3: Fix fdatasync() for files with only i_size changes

commit 156bddd8e505b295540f3ca0e27dda68cb0d49aa upstream.

Code tracking when transaction needs to be committed on fdatasync(2) forgets
to handle a situation when only inode's i_size is changed. Thus in such
situations fdatasync(2) doesn't force transaction with new i_size to disk
and that can result in wrong i_size after a crash.

Fix the issue by updating inode's i_datasync_tid whenever its size is
updated.

Reported-by: Kristian Nielsen <knielsen@knielsen-hq.org>
Signed-off-by: Jan Kara <jack@suse.cz>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
index 5b3f907..71b263f 100644 (file)
--- a/fs/ext3/inode.c
+++ b/fs/ext3/inode.c
@@ -3072,6 +3072,8 @@ static int ext3_do_update_inode(handle_t *handle,
        struct ext3_inode_info *ei = EXT3_I(inode);
        struct buffer_head *bh = iloc->bh;
        int err = 0, rc, block;
+       int need_datasync = 0;
+       __le32 disksize;
 
 again:
        /* we can't allow multiple procs in here at once, its a bit racey */
@@ -3109,7 +3111,11 @@ again:
                raw_inode->i_gid_high = 0;
        }
        raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
-       raw_inode->i_size = cpu_to_le32(ei->i_disksize);
+       disksize = cpu_to_le32(ei->i_disksize);
+       if (disksize != raw_inode->i_size) {
+               need_datasync = 1;
+               raw_inode->i_size = disksize;
+       }
        raw_inode->i_atime = cpu_to_le32(inode->i_atime.tv_sec);
        raw_inode->i_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
        raw_inode->i_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
@@ -3125,8 +3131,11 @@ again:
        if (!S_ISREG(inode->i_mode)) {
                raw_inode->i_dir_acl = cpu_to_le32(ei->i_dir_acl);
        } else {
-               raw_inode->i_size_high =
-                       cpu_to_le32(ei->i_disksize >> 32);
+               disksize = cpu_to_le32(ei->i_disksize >> 32);
+               if (disksize != raw_inode->i_size_high) {
+                       raw_inode->i_size_high = disksize;
+                       need_datasync = 1;
+               }
                if (ei->i_disksize > 0x7fffffffULL) {
                        struct super_block *sb = inode->i_sb;
                        if (!EXT3_HAS_RO_COMPAT_FEATURE(sb,
@@ -3179,6 +3188,8 @@ again:
        ext3_clear_inode_state(inode, EXT3_STATE_NEW);
 
        atomic_set(&ei->i_sync_tid, handle->h_transaction->t_tid);
+       if (need_datasync)
+               atomic_set(&ei->i_datasync_tid, handle->h_transaction->t_tid);
 out_brelse:
        brelse (bh);
        ext3_std_error(inode->i_sb, err);