ext4: fix fdatasync() for files with only i_size changes

commit b71fc079b5d8f42b2a52743c8d2f1d35d655b1c5 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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index efe63632474a4ad7758eb19840bdbb6e95cd7d24..babf4480c4ae2dd4685f7501744a455f355962fa 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5121,6 +5121,7 @@ static int ext4_do_update_inode(handle_t *handle,
        struct ext4_inode_info *ei = EXT4_I(inode);
        struct buffer_head *bh = iloc->bh;
        int err = 0, rc, block;
+       int need_datasync = 0;
 
        /* For fields not not tracking in the in-memory inode,
         * initialise them to zero for new inodes. */
@@ -5169,7 +5170,10 @@ static int ext4_do_update_inode(handle_t *handle,
                raw_inode->i_file_acl_high =
                        cpu_to_le16(ei->i_file_acl >> 32);
        raw_inode->i_file_acl_lo = cpu_to_le32(ei->i_file_acl);
-       ext4_isize_set(raw_inode, ei->i_disksize);
+       if (ei->i_disksize != ext4_isize(raw_inode)) {
+               ext4_isize_set(raw_inode, ei->i_disksize);
+               need_datasync = 1;
+       }
        if (ei->i_disksize > 0x7fffffffULL) {
                struct super_block *sb = inode->i_sb;
                if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
@@ -5222,7 +5226,7 @@ static int ext4_do_update_inode(handle_t *handle,
                err = rc;
        ext4_clear_inode_state(inode, EXT4_STATE_NEW);
 
-       ext4_update_inode_fsync_trans(handle, inode, 0);
+       ext4_update_inode_fsync_trans(handle, inode, need_datasync);
 out_brelse:
        brelse(bh);
        ext4_std_error(inode->i_sb, err);