[PATCH v2 2/2] ext4: Do not populate extents tree with outdated offsets while shifting extents

Roman Pen
2017-01-06T20:26:18Z

Inside ext4_ext_shift_extents() function ext4_find_extent() is called
without EXT4_EX_NOCACHE flag, which should prevent cache population.

This leads to oudated offsets in the extents tree and wrong blocks
afterwards.

Patch fixes the problem providing EXT4_EX_NOCACHE flag for each
ext4_find_extents() call inside ext4_ext_shift_extents function.

Signed-off-by: Roman Pen <roman.penyaev@profitbricks.com>
Cc: Namjae Jeon <namjae.jeon@samsung.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: linux-ext4@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
fs/ext4/extents.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 4d3014b5a3f9..2a97dff87b96 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -5334,7 +5334,8 @@ ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
ext4_lblk_t stop, *iterator, ex_start, ex_end;

/* Let path point to the last extent */
- path = ext4_find_extent(inode, EXT_MAX_BLOCKS - 1, NULL, 0);
+ path = ext4_find_extent(inode, EXT_MAX_BLOCKS - 1, NULL,
+ EXT4_EX_NOCACHE);
if (IS_ERR(path))
return PTR_ERR(path);

@@ -5350,7 +5351,8 @@ ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
* sure the hole is big enough to accommodate the shift.
*/
if (SHIFT == SHIFT_LEFT) {
- path = ext4_find_extent(inode, start - 1, &path, 0);
+ path = ext4_find_extent(inode, start - 1, &path,
+ EXT4_EX_NOCACHE);
if (IS_ERR(path))
return PTR_ERR(path);
depth = path->p_depth;
@@ -5388,7 +5390,8 @@ ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
* becomes NULL to indicate the end of the loop.
*/
while (iterator && start <= stop) {
- path = ext4_find_extent(inode, *iterator, &path, 0);
+ path = ext4_find_extent(inode, *iterator, &path,
+ EXT4_EX_NOCACHE);
if (IS_ERR(path))
return PTR_ERR(path);
depth = path->p_depth;
--
2.10.2