btrfs: pass NOWAIT for set/clear extent bits as another bit

The only flags we now pass to set_extent_bit/__clear_extent_bit are
GFP_NOFS and GFP_NOWAIT (a few functions handling mappings). This
requires an extra parameter to be passed everywhere but is almost always
the same.

Encode the GFP_NOWAIT as an artificial extent bit and extract the
real bits and gfp mask in the lowest level helpers. Now the passed
gfp mask is not actually used and can be removed.

Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/fs/btrfs/extent-io-tree.c b/fs/btrfs/extent-io-tree.c
index 29a225836e28..83e40c02f62e 100644
--- a/fs/btrfs/extent-io-tree.c
+++ b/fs/btrfs/extent-io-tree.c
@@ -533,6 +533,16 @@ static struct extent_state *clear_state_bit(struct extent_io_tree *tree,
 }
 
 /*
+ * Detect if extent bits request NOWAIT semantics and set the gfp mask accordingly,
+ * unset the EXTENT_NOWAIT bit.
+ */
+static void set_gfp_mask_from_bits(u32 *bits, gfp_t *mask)
+{
+	*mask = (*bits & EXTENT_NOWAIT ? GFP_NOWAIT : GFP_NOFS);
+	*bits &= EXTENT_NOWAIT - 1;
+}
+
+/*
  * Clear some bits on a range in the tree.  This may require splitting or
  * inserting elements in the tree, so the gfp mask is used to indicate which
  * allocations or sleeping are allowed.
@@ -557,6 +567,7 @@ int __clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 	int wake;
 	int delete = (bits & EXTENT_CLEAR_ALL_BITS);
 
+	set_gfp_mask_from_bits(&bits, &mask);
 	btrfs_debug_check_extent_io_range(tree, start, end);
 	trace_btrfs_clear_extent_bit(tree, start, end - start + 1, bits);
 
@@ -979,6 +990,7 @@ static int __set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 	u64 last_end;
 	u32 exclusive_bits = (bits & EXTENT_LOCKED);
 
+	set_gfp_mask_from_bits(&bits, &mask);
 	btrfs_debug_check_extent_io_range(tree, start, end);
 	trace_btrfs_set_extent_bit(tree, start, end - start + 1, bits);