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Subject[ 73/85] ext3: Fix fdatasync() for files with only i_size changes
Date
From: Greg KH <gregkh@linuxfoundation.org>

3.4-stable review patch. If anyone has any objections, please let me know.

------------------

From: Jan Kara <jack@suse.cz>

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/ext3/inode.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)

--- a/fs/ext3/inode.c
+++ b/fs/ext3/inode.c
@@ -3068,6 +3068,8 @@ static int ext3_do_update_inode(handle_t
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 */
@@ -3105,7 +3107,11 @@ 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);
@@ -3121,8 +3127,11 @@ 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,
@@ -3175,6 +3184,8 @@ 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);



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