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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: bb06664a53 ("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>
This commit is contained in:
Chao Yu 2017-11-23 23:26:52 +08:00 committed by Jaegeuk Kim
parent e17d488bce
commit 21020812c9
1 changed files with 9 additions and 11 deletions
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20
fs/f2fs/file.c
View File

@ -1186,14 +1186,14 @@ 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);
@ -1212,9 +1212,8 @@ 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;
}
@ -1385,6 +1384,9 @@ 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)
@ -1395,9 +1397,6 @@ 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;
@ -1425,10 +1424,9 @@ 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;
}