From 3f12c94d1b3cc3c9a403017b337a9d6f91a25465 Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Thu, 23 Nov 2017 23:26:52 +0800 Subject: [PATCH] f2fs: fix lock dependency in between dio_rwsem & i_mmap_sem 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 Signed-off-by: Jaegeuk Kim --- fs/f2fs/file.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-) diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index 25038cfc9217..db06eb788d56 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -1185,14 +1185,14 @@ static int f2fs_collapse_range(struct inode *inode, loff_t offset, loff_t len) 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); @@ -1211,9 +1211,8 @@ static int f2fs_collapse_range(struct inode *inode, loff_t offset, loff_t len) 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; } @@ -1384,6 +1383,9 @@ static int f2fs_insert_range(struct inode *inode, loff_t offset, loff_t len) 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) @@ -1394,9 +1396,6 @@ static int f2fs_insert_range(struct inode *inode, loff_t offset, loff_t len) 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; @@ -1424,10 +1423,9 @@ static int f2fs_insert_range(struct inode *inode, loff_t offset, loff_t len) 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; } -- 2.20.1