From 08b39fbd59781729da9fb6367decaf4804a22721 Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Thu, 8 Oct 2015 13:27:34 +0800 Subject: f2fs crypto: fix racing of accessing encrypted page among different competitors Since we use different page cache (normally inode's page cache for R/W and meta inode's page cache for GC) to cache the same physical block which is belong to an encrypted inode. Writeback of these two page cache should be exclusive, but now we didn't handle writeback state well, so there may be potential racing problem: a) kworker: f2fs_gc: - f2fs_write_data_pages - f2fs_write_data_page - do_write_data_page - write_data_page - f2fs_submit_page_mbio (page#1 in inode's page cache was queued in f2fs bio cache, and be ready to write to new blkaddr) - gc_data_segment - move_encrypted_block - pagecache_get_page (page#2 in meta inode's page cache was cached with the invalid datas of physical block located in new blkaddr) - f2fs_submit_page_mbio (page#1 was submitted, later, page#2 with invalid data will be submitted) b) f2fs_gc: - gc_data_segment - move_encrypted_block - f2fs_submit_page_mbio (page#1 in meta inode's page cache was queued in f2fs bio cache, and be ready to write to new blkaddr) user thread: - f2fs_write_begin - f2fs_submit_page_bio (we submit the request to block layer to update page#2 in inode's page cache with physical block located in new blkaddr, so here we may read gabbage data from new blkaddr since GC hasn't writebacked the page#1 yet) This patch fixes above potential racing problem for encrypted inode. Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim --- fs/f2fs/segment.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'fs/f2fs/segment.c') diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index 5337fd6fdc32..f37c21233b5c 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -1484,6 +1484,23 @@ void f2fs_wait_on_page_writeback(struct page *page, } } +void f2fs_wait_on_encrypted_page_writeback(struct f2fs_sb_info *sbi, + block_t blkaddr) +{ + struct page *cpage; + + if (blkaddr == NEW_ADDR) + return; + + f2fs_bug_on(sbi, blkaddr == NULL_ADDR); + + cpage = find_lock_page(META_MAPPING(sbi), blkaddr); + if (cpage) { + f2fs_wait_on_page_writeback(cpage, DATA); + f2fs_put_page(cpage, 1); + } +} + static int read_compacted_summaries(struct f2fs_sb_info *sbi) { struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi); -- cgit v1.2.3