Btrfs: Change find_extent_buffer to use TestSetPageLocked

This makes it possible for callers to check for extent_buffers in cache
without deadlocking against any btree locks held.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

2 files changed, 6 insertions, 3 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index a9b3a25a45b7..dc3c03c6612d 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1438,7 +1438,6 @@ static int pin_down_bytes(struct btrfs_root *root, u64 bytenr, u32 num_bytes,
         int err = 0;
 
         if (!pending) {
-#if 0
                 struct extent_buffer *buf;
                 buf = btrfs_find_tree_block(root, bytenr, num_bytes);
                 if (buf) {
@@ -1460,7 +1459,6 @@ static int pin_down_bytes(struct btrfs_root *root, u64 bytenr, u32 num_bytes,
                         }
                         free_extent_buffer(buf);
                 }
-#endif
                 update_pinned_extents(root, bytenr, num_bytes, 1);
         } else {
                 set_extent_bits(&root->fs_info->pending_del,
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index bd15cdcaba95..40a5f53cb040 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2808,10 +2808,15 @@ struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
                 goto lru_add;
 
         for (i = 0; i < num_pages; i++, index++) {
-                p = find_lock_page(mapping, index);
+                p = find_get_page(mapping, index);
                 if (!p) {
                         goto fail;
                 }
+                if (TestSetPageLocked(p)) {
+                        page_cache_release(p);
+                        goto fail;
+                }
+
                 set_page_extent_mapped(p);
                 mark_page_accessed(p);