[PATCH 3.19.y-ckt 016/107] bufferhead: Add _gfp version for sb_getblk()

[Kamal Mostafa]

3.19.8-ckt5 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Nikolay Borisov <kernel at kyup.com>

commit bd7ade3cd9b0850264306f5c2b79024a417b6396 upstream.

sb_getblk() is used during ext4 (and possibly other FSes) writeback
paths. Sometimes such path require allocating memory and guaranteeing
that such allocation won't block. Currently, however, there is no way
to provide user flags for sb_getblk which could lead to deadlocks.

This patch implements a sb_getblk_gfp with the only difference it can
accept user-provided GFP flags.

Signed-off-by: Nikolay Borisov <kernel at kyup.com>
Signed-off-by: Theodore Ts'o <tytso at mit.edu>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 include/linux/buffer_head.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index 73b4522..e6797de 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -317,6 +317,13 @@ sb_getblk(struct super_block *sb, sector_t block)
 	return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
 }
 
+
+static inline struct buffer_head *
+sb_getblk_gfp(struct super_block *sb, sector_t block, gfp_t gfp)
+{
+	return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, gfp);
+}
+
 static inline struct buffer_head *
 sb_find_get_block(struct super_block *sb, sector_t block)
 {
-- 
1.9.1