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Subject[PATCH 3.12 036/181] xfs: fix the wrong new_size/rnew_size at xfs_iext_realloc_direct()
Date
From: Jie Liu <jeff.liu@oracle.com>

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

===============

commit 17ec81c15fd022842f9bc947841ba9fb9eb52591 upstream.

At xfs_iext_realloc_direct(), the new_size is changed by adding
if_bytes if originally the extent records are stored at the inline
extent buffer, and we have to switch from it to a direct extent
list for those new allocated extents, this is wrong. e.g,

Create a file with three extents which was showing as following,

xfs_io -f -c "truncate 100m" /xfs/testme

for i in $(seq 0 5 10); do
offset=$(($i * $((1 << 20))))
xfs_io -c "pwrite $offset 1m" /xfs/testme
done

Inline
------
irec: if_bytes bytes_diff new_size
1st 0 16 16
2nd 16 16 32

Switching
--------- rnew_size
3rd 32 16 48 + 32 = 80 roundup=128

In this case, the desired value of new_size should be 48, and then
it will be roundup to 64 and be assigned to rnew_size.

However, this issue has been covered by resetting the if_bytes to
the new_size which is calculated at the begnning of xfs_iext_add()
before leaving out this function, and in turn make the rnew_size
correctly again. Hence, this can not be detected via xfstestes.

This patch fix above problem and revise the new_size comments at
xfs_iext_realloc_direct() to make it more readable. Also, fix the
comments while switching from the inline extent buffer to a direct
extent list to reflect this change.

Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
fs/xfs/xfs_inode_fork.c | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/fs/xfs/xfs_inode_fork.c b/fs/xfs/xfs_inode_fork.c
index 02f1083955bb..4fa56fcb38d1 100644
--- a/fs/xfs/xfs_inode_fork.c
+++ b/fs/xfs/xfs_inode_fork.c
@@ -1359,7 +1359,7 @@ xfs_iext_remove_indirect(
void
xfs_iext_realloc_direct(
xfs_ifork_t *ifp, /* inode fork pointer */
- int new_size) /* new size of extents */
+ int new_size) /* new size of extents after adding */
{
int rnew_size; /* real new size of extents */

@@ -1397,13 +1397,8 @@ xfs_iext_realloc_direct(
rnew_size - ifp->if_real_bytes);
}
}
- /*
- * Switch from the inline extent buffer to a direct
- * extent list. Be sure to include the inline extent
- * bytes in new_size.
- */
+ /* Switch from the inline extent buffer to a direct extent list */
else {
- new_size += ifp->if_bytes;
if (!is_power_of_2(new_size)) {
rnew_size = roundup_pow_of_two(new_size);
}
--
2.0.0


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