[3.11.y.z extended stable] Patch "reiserfs: fix race in readdir" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    reiserfs: fix race in readdir

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From ff0c57b6ff93bc02531b8e7f642d1563239d181f Mon Sep 17 00:00:00 2001
From: Jeff Mahoney <jeffm at suse.com>
Date: Wed, 2 Apr 2014 14:40:26 -0400
Subject: reiserfs: fix race in readdir

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 at suse.com>
Signed-off-by: Jan Kara <jack at suse.cz>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 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 03e4ca5..79b7b55 100644
--- a/fs/reiserfs/dir.c
+++ b/fs/reiserfs/dir.c
@@ -124,6 +124,7 @@ 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 */
@@ -195,8 +196,9 @@ 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,
--
1.9.1