This is a note to let you know that I've just added the patch titled
f2fs: fix lock dependency in between dio_rwsem & i_mmap_sem
to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
f2fs-fix-lock-dependency-in-between-dio_rwsem-i_mmap_sem.patch
and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Mon Apr 9 10:16:32 CEST 2018
From: Chao Yu <yuchao0@xxxxxxxxxx>
Date: Thu, 23 Nov 2017 23:26:52 +0800
Subject: f2fs: fix lock dependency in between dio_rwsem & i_mmap_sem
From: Chao Yu <yuchao0@xxxxxxxxxx>
[ Upstream commit 21020812c9e1ab593367fad9ce579f842a0b406d ]
test/generic/208 reports a potential deadlock as below:
Chain exists of:
&mm->mmap_sem --> &fi->i_mmap_sem --> &fi->dio_rwsem[WRITE]
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&fi->dio_rwsem[WRITE]);
lock(&fi->i_mmap_sem);
lock(&fi->dio_rwsem[WRITE]);
lock(&mm->mmap_sem);
This patch changes the lock dependency as below in fallocate() to
fix this issue:
- dio_rwsem
- i_mmap_sem
Fixes: bb06664a534b ("f2fs: avoid race in between GC and block exchange")
Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx>
Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/f2fs/file.c | 20 +++++++++-----------
1 file changed, 9 insertions(+), 11 deletions(-)
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1186,14 +1186,14 @@ static int f2fs_collapse_range(struct in
pg_start = offset >> PAGE_SHIFT;
pg_end = (offset + len) >> PAGE_SHIFT;
+ /* avoid gc operation during block exchange */
+ down_write(&F2FS_I(inode)->dio_rwsem[WRITE]);
+
down_write(&F2FS_I(inode)->i_mmap_sem);
/* write out all dirty pages from offset */
ret = filemap_write_and_wait_range(inode->i_mapping, offset, LLONG_MAX);
if (ret)
- goto out;
-
- /* avoid gc operation during block exchange */
- down_write(&F2FS_I(inode)->dio_rwsem[WRITE]);
+ goto out_unlock;
truncate_pagecache(inode, offset);
@@ -1212,9 +1212,8 @@ static int f2fs_collapse_range(struct in
if (!ret)
f2fs_i_size_write(inode, new_size);
out_unlock:
- up_write(&F2FS_I(inode)->dio_rwsem[WRITE]);
-out:
up_write(&F2FS_I(inode)->i_mmap_sem);
+ up_write(&F2FS_I(inode)->dio_rwsem[WRITE]);
return ret;
}
@@ -1385,6 +1384,9 @@ static int f2fs_insert_range(struct inod
f2fs_balance_fs(sbi, true);
+ /* avoid gc operation during block exchange */
+ down_write(&F2FS_I(inode)->dio_rwsem[WRITE]);
+
down_write(&F2FS_I(inode)->i_mmap_sem);
ret = truncate_blocks(inode, i_size_read(inode), true);
if (ret)
@@ -1395,9 +1397,6 @@ static int f2fs_insert_range(struct inod
if (ret)
goto out;
- /* avoid gc operation during block exchange */
- down_write(&F2FS_I(inode)->dio_rwsem[WRITE]);
-
truncate_pagecache(inode, offset);
pg_start = offset >> PAGE_SHIFT;
@@ -1425,10 +1424,9 @@ static int f2fs_insert_range(struct inod
if (!ret)
f2fs_i_size_write(inode, new_size);
-
- up_write(&F2FS_I(inode)->dio_rwsem[WRITE]);
out:
up_write(&F2FS_I(inode)->i_mmap_sem);
+ up_write(&F2FS_I(inode)->dio_rwsem[WRITE]);
return ret;
}
Patches currently in stable-queue which might be from yuchao0@xxxxxxxxxx are
queue-4.15/f2fs-fix-lock-dependency-in-between-dio_rwsem-i_mmap_sem.patch