[PATCH 3.12 079/182] reiserfs: fix race in readdir

Jiri Slaby
2014-05-13T09:40:39Z

From: Jeff Mahoney <jeffm@suse.com>

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

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

commit 01d8885785a60ae8f4c37b0ed75bdc96d0fc6a44 upstream.

jdm-20004 reiserfs_delete_xattrs: Couldn't delete all xattrs (-2)

The -ENOENT is due to readdir calling dir_emit on the same entry twice.

If the dir_emit callback sleeps and the tree is changed underneath us,
we won't be able to trust deh_offset(deh) anymore. We need to save
next_pos before we might sleep so we can find the next entry.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
fs/reiserfs/dir.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/reiserfs/dir.c b/fs/reiserfs/dir.c
index 1fd2051109a3..af677353a3f5 100644
--- a/fs/reiserfs/dir.c
+++ b/fs/reiserfs/dir.c
@@ -125,6 +125,7 @@ int reiserfs_readdir_inode(struct inode *inode, struct dir_context *ctx)
int d_reclen;
char *d_name;
ino_t d_ino;
+ loff_t cur_pos = deh_offset(deh);

if (!de_visible(deh))
/* it is hidden entry */
@@ -196,8 +197,9 @@ int reiserfs_readdir_inode(struct inode *inode, struct dir_context *ctx)
if (local_buf != small_buf) {
kfree(local_buf);
}
- // next entry should be looked for with such offset
- next_pos = deh_offset(deh) + 1;
+
+ /* deh_offset(deh) may be invalid now. */
+ next_pos = cur_pos + 1;

if (item_moved(&tmp_ih, &path_to_entry)) {
set_cpu_key_k_offset(&pos_key,
--
1.9.3