reiserfs: Fix softlockup while waiting on an inode

When we wait for an inode through reiserfs_iget(), we hold
the reiserfs lock. And waiting for an inode may imply waiting
for its writeback. But the inode writeback path may also require
the reiserfs lock, which leads to a deadlock.

We just need to release the reiserfs lock from reiserfs_iget()
to fix this.

Reported-by: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Tested-by: Christian Kujau <lists@nerdbynature.de>
Cc: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/reiserfs/inode.c b/fs/reiserfs/inode.c
index 9087b10..2df0f5c 100644 (file)
--- a/fs/reiserfs/inode.c
+++ b/fs/reiserfs/inode.c
@@ -1497,9 +1497,11 @@ struct inode *reiserfs_iget(struct super_block *s, const struct cpu_key *key)
 
        args.objectid = key->on_disk_key.k_objectid;
        args.dirid = key->on_disk_key.k_dir_id;
+       reiserfs_write_unlock(s);
        inode = iget5_locked(s, key->on_disk_key.k_objectid,
                             reiserfs_find_actor, reiserfs_init_locked_inode,
                             (void *)(&args));
+       reiserfs_write_lock(s);
        if (!inode)
                return ERR_PTR(-ENOMEM);