[PATCH] xfs: fix memory reclaim deadlock on agi buffer

[Peter Watkins <treestem@xxxxxxxxx>]

Note xfs_iget can be called while holding a locked agi buffer. If
it goes into memory reclaim then inode teardown may try to lock the
same buffer. Prevent the deadlock by calling radix_tree_preload
with GFP_NOFS.

Signed-off-by: Peter Watkins <treestem@xxxxxxxxx>
---
 fs/xfs/xfs_iget.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/xfs_iget.c b/fs/xfs/xfs_iget.c
index bcc6c24..8c6f806 100644
--- a/fs/xfs/xfs_iget.c
+++ b/fs/xfs/xfs_iget.c
@@ -334,9 +334,10 @@ xfs_iget_cache_miss(
        /*
         * Preload the radix tree so we can insert safely under the
         * write spinlock. Note that we cannot sleep inside the preload
-        * region.
+        * region. Since we can be called from transaction context, don't
+        * recurse into the file system.
         */
-       if (radix_tree_preload(GFP_KERNEL)) {
+       if (radix_tree_preload(GFP_NOFS)) {
                error = EAGAIN;
                goto out_destroy;
        }
-- 
1.7.0.4