[PATCH 3.4 004/107] ext4: avoid deadlocks in the writeback path by using sb_getblk_gfp

lizf
2016-03-16T08:45:57Z

From: Nikolay Borisov <kernel@kyup.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@kyup.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li <lizefan@huawei.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