linux-kernel - [PATCH 3.4 004/107] ext4: avoid deadlocks in the writeback path by using sb_getblk

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Date:	Wed, 16 Mar 2016 16:04:58 +0800
From:	lizf@...nel.org
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Nikolay Borisov <kernel@...p.com>,
	Theodore Ts'o <tytso@....edu>, Zefan Li <lizefan@...wei.com>
Subject: [PATCH 3.4 004/107] ext4: avoid deadlocks in the writeback path by using sb_getblk_gfp

From: Nikolay Borisov <kernel@...p.com>

3.4.111-rc1 review patch.  If anyone has any objections, please let me know.

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


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@...p.com>
Signed-off-by: Theodore Ts'o <tytso@....edu>
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li <lizefan@...wei.com>
---
 fs/ext4/extents.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index bbe09a9..e05cb4c 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -699,7 +699,8 @@ ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block,
 		path[ppos].p_depth = i;
 		path[ppos].p_ext = NULL;
 
-		bh = sb_getblk(inode->i_sb, path[ppos].p_block);
+		bh = sb_getblk_gfp(inode->i_sb, path[ppos].p_block,
+				   __GFP_MOVABLE | GFP_NOFS);
 		if (unlikely(!bh)) {
 			ret = -ENOMEM;
 			goto err;
@@ -904,7 +905,7 @@ 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 (!bh) {
 		err = -ENOMEM;
 		goto cleanup;
@@ -1088,7 +1089,7 @@ 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 (!bh)
 		return -ENOMEM;
 	lock_buffer(bh);
-- 
1.9.1