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f2fs: fix avoid race between truncate and background GC

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Thread A				Background GC
- f2fs_setattr isize to 0
 - truncate_setsize
					- gc_data_segment
					 - f2fs_get_read_data_page page #0
					  - set_page_dirty
					  - set_cold_data
 - f2fs_truncate

- f2fs_setattr isize to 4k
- read 4k <--- hit data in cached page #0

Above race condition can cause read out invalid data in a truncated
page, fix it by i_gc_rwsem[WRITE] lock.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Chao Yu
2018-08-05 23:04:25 +08:00
committed by Jaegeuk Kim
parent c7079853c8
commit a33c150237
2 changed files with 28 additions and 15 deletions
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4
fs/f2fs/data.c
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@@ -2199,8 +2199,12 @@ static void f2fs_write_failed(struct address_space *mapping, loff_t to)
if (to > i_size) {
down_write(&F2FS_I(inode)->i_mmap_sem);
down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
truncate_pagecache(inode, i_size);
f2fs_truncate_blocks(inode, i_size, true);
up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
up_write(&F2FS_I(inode)->i_mmap_sem);
}
}