diff options
author | Hyeong-Jun Kim <hj514.kim@samsung.com> | 2021-12-10 13:30:12 +0900 |
---|---|---|
committer | Jaegeuk Kim <jaegeuk@kernel.org> | 2021-12-14 11:17:55 -0800 |
commit | 7377e853967ba45bf409e3b5536624d2cbc99f21 (patch) | |
tree | c6d4559a1905816d6bb72ecbf549e239f5dea081 /fs/f2fs | |
parent | 19bdba5265624ba6b9d9dd936a0c6ccc167cfe80 (diff) | |
download | linux-7377e853967ba45bf409e3b5536624d2cbc99f21.tar.bz2 |
f2fs: compress: fix potential deadlock of compress file
There is a potential deadlock between writeback process and a process
performing write_begin() or write_cache_pages() while trying to write
same compress file, but not compressable, as below:
[Process A] - doing checkpoint
[Process B] [Process C]
f2fs_write_cache_pages()
- lock_page() [all pages in cluster, 0-31]
- f2fs_write_multi_pages()
- f2fs_write_raw_pages()
- f2fs_write_single_data_page()
- f2fs_do_write_data_page()
- return -EAGAIN [f2fs_trylock_op() failed]
- unlock_page(page) [e.g., page 0]
- generic_perform_write()
- f2fs_write_begin()
- f2fs_prepare_compress_overwrite()
- prepare_compress_overwrite()
- lock_page() [e.g., page 0]
- lock_page() [e.g., page 1]
- lock_page(page) [e.g., page 0]
Since there is no compress process, it is no longer necessary to hold
locks on every pages in cluster within f2fs_write_raw_pages().
This patch changes f2fs_write_raw_pages() to release all locks first
and then perform write same as the non-compress file in
f2fs_write_cache_pages().
Fixes: 4c8ff7095bef ("f2fs: support data compression")
Signed-off-by: Hyeong-Jun Kim <hj514.kim@samsung.com>
Signed-off-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Youngjin Gil <youngjin.gil@samsung.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Diffstat (limited to 'fs/f2fs')
-rw-r--r-- | fs/f2fs/compress.c | 50 |
1 files changed, 22 insertions, 28 deletions
diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c index fb9e5149af5d..4b49038d150d 100644 --- a/fs/f2fs/compress.c +++ b/fs/f2fs/compress.c @@ -1456,25 +1456,38 @@ static int f2fs_write_raw_pages(struct compress_ctx *cc, enum iostat_type io_type) { struct address_space *mapping = cc->inode->i_mapping; - int _submitted, compr_blocks, ret; - int i = -1, err = 0; + int _submitted, compr_blocks, ret, i; compr_blocks = f2fs_compressed_blocks(cc); - if (compr_blocks < 0) { - err = compr_blocks; - goto out_err; + + for (i = 0; i < cc->cluster_size; i++) { + if (!cc->rpages[i]) + continue; + + redirty_page_for_writepage(wbc, cc->rpages[i]); + unlock_page(cc->rpages[i]); } + if (compr_blocks < 0) + return compr_blocks; + for (i = 0; i < cc->cluster_size; i++) { if (!cc->rpages[i]) continue; retry_write: + lock_page(cc->rpages[i]); + if (cc->rpages[i]->mapping != mapping) { +continue_unlock: unlock_page(cc->rpages[i]); continue; } - BUG_ON(!PageLocked(cc->rpages[i])); + if (!PageDirty(cc->rpages[i])) + goto continue_unlock; + + if (!clear_page_dirty_for_io(cc->rpages[i])) + goto continue_unlock; ret = f2fs_write_single_data_page(cc->rpages[i], &_submitted, NULL, NULL, wbc, io_type, @@ -1489,26 +1502,15 @@ retry_write: * avoid deadlock caused by cluster update race * from foreground operation. */ - if (IS_NOQUOTA(cc->inode)) { - err = 0; - goto out_err; - } + if (IS_NOQUOTA(cc->inode)) + return 0; ret = 0; cond_resched(); congestion_wait(BLK_RW_ASYNC, DEFAULT_IO_TIMEOUT); - lock_page(cc->rpages[i]); - - if (!PageDirty(cc->rpages[i])) { - unlock_page(cc->rpages[i]); - continue; - } - - clear_page_dirty_for_io(cc->rpages[i]); goto retry_write; } - err = ret; - goto out_err; + return ret; } *submitted += _submitted; @@ -1517,14 +1519,6 @@ retry_write: f2fs_balance_fs(F2FS_M_SB(mapping), true); return 0; -out_err: - for (++i; i < cc->cluster_size; i++) { - if (!cc->rpages[i]) - continue; - redirty_page_for_writepage(wbc, cc->rpages[i]); - unlock_page(cc->rpages[i]); - } - return err; } int f2fs_write_multi_pages(struct compress_ctx *cc, |