gfs2: Use mapping->gfp_mask for metadata inodes

Set mapping->gfp mask to GFP_NOFS for all metadata inodes so that
allocating pages in the address space of those inodes won't call back
into the filesystem.  This allows to switch back from
find_or_create_page() to grab_cache_page() in two places.

Partially reverts commit 220cca2a4f58 ("GFS2: Change truncate page
allocation to be GFP_NOFS").

Thanks to Dan Carpenter <dan.carpenter@linaro.org> for pointing out a
Smatch static checker warning.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

1 files changed, 10 insertions, 4 deletions

diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index 17c994a0c0d0..fadf5c157603 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -276,10 +276,16 @@ struct inode *gfs2_lookup_simple(struct inode *dip, const char *name)
 	 * gfs2_lookup_simple callers expect ENOENT
 	 * and do not check for NULL.
 	 */
-	if (inode == NULL)
-		return ERR_PTR(-ENOENT);
-	else
-		return inode;
+	if (IS_ERR_OR_NULL(inode))
+		return inode ? inode : ERR_PTR(-ENOENT);
+
+	/*
+	 * Must not call back into the filesystem when allocating
+	 * pages in the metadata inode's address space.
+	 */
+	mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
+
+	return inode;
 }