btrfs: prepare to drop gfp mask parameter from clear_extent_bit

Use __clear_extent_bit directly in case we want to pass unknown
gfp flags. Otherwise all clear_extent_bit callers use GFP_NOFS, so we
can sink them to the function and reduce argument count, at the cost
that __clear_extent_bit has to be exported.
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent_io.c

@@ -581,7 +581,7 @@ static void extent_io_tree_panic(struct extent_io_tree *tree, int err)
  *
  * This takes the tree lock, and returns 0 on success and < 0 on error.
  */
-static int __clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
+int __clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 			      unsigned bits, int wake, int delete,
 			      struct extent_state **cached_state,
 			      gfp_t mask, struct extent_changeset *changeset)
@@ -4232,9 +4232,9 @@ static int try_release_extent_state(struct extent_map_tree *map,
 		 * at this point we can safely clear everything except the
 		 * locked bit and the nodatasum bit
 		 */
-		ret = clear_extent_bit(tree, start, end,
+		ret = __clear_extent_bit(tree, start, end,
 				 ~(EXTENT_LOCKED | EXTENT_NODATASUM),
-				 0, 0, NULL, mask);
+				 0, 0, NULL, mask, NULL);
 
 		/* if clear_extent_bit failed for enomem reasons,
 		 * we can't allow the release to continue.

fs/btrfs/extent_io.h

@@ -301,6 +301,10 @@ int clear_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
 int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 		     unsigned bits, int wake, int delete,
 		     struct extent_state **cached, gfp_t mask);
+int __clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
+		     unsigned bits, int wake, int delete,
+		     struct extent_state **cached, gfp_t mask,
+		     struct extent_changeset *changeset);
 
 static inline int unlock_extent(struct extent_io_tree *tree, u64 start, u64 end)
 {
@@ -311,8 +315,8 @@ static inline int unlock_extent(struct extent_io_tree *tree, u64 start, u64 end)
 static inline int unlock_extent_cached(struct extent_io_tree *tree, u64 start,
 		u64 end, struct extent_state **cached, gfp_t mask)
 {
-	return clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, cached,
-				mask);
+	return __clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, cached,
+				mask, NULL);
 }
 
 static inline int clear_extent_bits(struct extent_io_tree *tree, u64 start,
@@ -342,8 +346,8 @@ static inline int set_extent_bits(struct extent_io_tree *tree, u64 start,
 static inline int clear_extent_uptodate(struct extent_io_tree *tree, u64 start,
 		u64 end, struct extent_state **cached_state, gfp_t mask)
 {
-	return clear_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, 0,
-				cached_state, mask);
+	return __clear_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, 0,
+				cached_state, mask, NULL);
 }
 
 static inline int set_extent_dirty(struct extent_io_tree *tree, u64 start,