[3.11.y.z extended stable] Patch "reiserfs: call truncate_setsize under tailpack mutex" 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: call truncate_setsize under tailpack mutex

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 14268efd8766d30fbf94f579060da2b7f80fdc8c Mon Sep 17 00:00:00 2001
From: Jeff Mahoney <jeffm at suse.com>
Date: Wed, 21 May 2014 13:28:07 -0400
Subject: reiserfs: call truncate_setsize under tailpack mutex

commit 22e7478ddbcb670e33fab72d0bbe7c394c3a2c84 upstream.

Prior to commit 0e4f6a791b1e (Fix reiserfs_file_release()), reiserfs
truncates serialized on i_mutex. They mostly still do, with the exception
of reiserfs_file_release. That blocks out other writers via the tailpack
mutex and the inode openers counter adjusted in reiserfs_file_open.

However, NFS will call reiserfs_setattr without having called ->open, so
we end up with a race when nfs is calling ->setattr while another
process is releasing the file. Ultimately, it triggers the
BUG_ON(inode->i_size != new_file_size) check in maybe_indirect_to_direct.

The solution is to pull the lock into reiserfs_setattr to encompass the
truncate_setsize call as well.

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/inode.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/reiserfs/inode.c b/fs/reiserfs/inode.c
index 0048cc16a6a8..9fa970e7b2cd 100644
--- a/fs/reiserfs/inode.c
+++ b/fs/reiserfs/inode.c
@@ -3217,8 +3217,14 @@ int reiserfs_setattr(struct dentry *dentry, struct iattr *attr)
 	    attr->ia_size != i_size_read(inode)) {
 		error = inode_newsize_ok(inode, attr->ia_size);
 		if (!error) {
+			/*
+			 * Could race against reiserfs_file_release
+			 * if called from NFS, so take tailpack mutex.
+			 */
+			mutex_lock(&REISERFS_I(inode)->tailpack);
 			truncate_setsize(inode, attr->ia_size);
-			reiserfs_vfs_truncate_file(inode);
+			reiserfs_truncate_file(inode, 1);
+			mutex_unlock(&REISERFS_I(inode)->tailpack);
 		}
 	}

--
1.9.1