[PATCH 3.19.y-ckt 017/107] ext4: avoid deadlocks in the writeback path by using sb_getblk_gfp

[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 c45653c341f5c8a0ce19c8f0ad4678640849cb86 upstream.

Switch ext4 to using sb_getblk_gfp with GFP_NOFS added to fix possible
deadlocks in the page writeback path.

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>
---
 fs/ext4/extents.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 410841e..4252860 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -503,7 +503,7 @@ __read_extent_tree_block(const char *function, unsigned int line,
 	struct buffer_head		*bh;
 	int				err;
 
-	bh = sb_getblk(inode->i_sb, pblk);
+	bh = sb_getblk_gfp(inode->i_sb, pblk, __GFP_MOVABLE | GFP_NOFS);
 	if (unlikely(!bh))
 		return ERR_PTR(-ENOMEM);
 
@@ -1088,7 +1088,7 @@ static int ext4_ext_split(handle_t *handle, struct inode *inode,
 		err = -EIO;
 		goto cleanup;
 	}
-	bh = sb_getblk(inode->i_sb, newblock);
+	bh = sb_getblk_gfp(inode->i_sb, newblock, __GFP_MOVABLE | GFP_NOFS);
 	if (unlikely(!bh)) {
 		err = -ENOMEM;
 		goto cleanup;
@@ -1282,7 +1282,7 @@ static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode,
 	if (newblock == 0)
 		return err;
 
-	bh = sb_getblk(inode->i_sb, newblock);
+	bh = sb_getblk_gfp(inode->i_sb, newblock, __GFP_MOVABLE | GFP_NOFS);
 	if (unlikely(!bh))
 		return -ENOMEM;
 	lock_buffer(bh);
-- 
1.9.1