4.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Chao Yu yuchao0@huawei.com
[ 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@huawei.com Signed-off-by: Jaegeuk Kim jaegeuk@kernel.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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; }