xfs: fix might_sleep() warning when initialising per-ag tree

The use of radix_tree_preload() only works if the radix tree was
initialised without the __GFP_WAIT flag. The per-ag tree uses
GFP_NOFS, so does not trigger allocation of new tree nodes from the
preloaded array. Hence it enters the allocator with a spinlock held
and triggers the might_sleep() warnings.

Reported-by; Chris Mason <chris.mason@oracle.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>

diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 2d811e5..ef1233b 100644 (file)
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -1254,7 +1254,7 @@ xfs_mountfs(
         * Allocate and initialize the per-ag data.
         */
        spin_lock_init(&mp->m_perag_lock);
-       INIT_RADIX_TREE(&mp->m_perag_tree, GFP_NOFS);
+       INIT_RADIX_TREE(&mp->m_perag_tree, GFP_ATOMIC);
        error = xfs_initialize_perag(mp, sbp->sb_agcount, &mp->m_maxagi);
        if (error) {
                cmn_err(CE_WARN, "XFS: Failed per-ag init: %d", error);