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

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.

CC: <stable@vger.kernel.org> # >= 2.6.32
Reported-by: Kristian Nielsen <knielsen@knielsen-hq.org>
Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 14 insertions, 3 deletions

diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
index a07597307fd1..ff574b4e345e 100644
--- 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;
         uid_t i_uid;
         gid_t i_gid;
 
@@ -3113,7 +3115,11 @@ 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);
@@ -3129,8 +3135,11 @@ 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,
@@ -3183,6 +3192,8 @@ 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);