btrfs: Implement set_extent_bits_nowait

It will be used in a future patch that will require modifying an
extent_io_tree struct under a spinlock.
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/extent_io.c

@@ -1368,6 +1368,13 @@ int set_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
 				changeset);
 }
 
+int set_extent_bits_nowait(struct extent_io_tree *tree, u64 start, u64 end,
+			   unsigned bits)
+{
+	return __set_extent_bit(tree, start, end, bits, 0, NULL, NULL,
+				GFP_NOWAIT, NULL);
+}
+
 int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 		     unsigned bits, int wake, int delete,
 		     struct extent_state **cached)

fs/btrfs/extent_io.h

@@ -328,6 +328,8 @@ int set_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
 int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 		   unsigned bits, u64 *failed_start,
 		   struct extent_state **cached_state, gfp_t mask);
+int set_extent_bits_nowait(struct extent_io_tree *tree, u64 start, u64 end,
+			   unsigned bits);
 
 static inline int set_extent_bits(struct extent_io_tree *tree, u64 start,
 		u64 end, unsigned bits)