f2fs: avoid GC causing encrypted file corrupted

Yunlong Song · Jaegeuk Kim · commit 9bf1a3f73927 · 2018-11-26T15:53:54.000-08:00
The encrypted file may be corrupted by GC in following case: Time 1: | segment 1 blkaddr = A | GC -> | segment 2 blkaddr = B | Encrypted block 1 is moved from blkaddr A of segment 1 to blkaddr B of segment 2, Time 2: | segment 1 blkaddr = B | GC -> | segment 3 blkaddr = C | Before page 1 is written back and if segment 2 become a victim, then page 1 is moved from blkaddr B of segment 2 to blkaddr Cof segment 3, during the GC process of Time 2, f2fs should wait for page 1 written back before reading it, or move_data_block will read a garbage block from blkaddr B since page is not written back to blkaddr B yet. Commit 6aa58d8 ("f2fs: readahead encrypted block during GC") introduce ra_data_block to read encrypted block, but it forgets to add f2fs_wait_on_page_writeback to avoid racing between GC and flush. Signed-off-by: Yunlong Song <yunlong.song@huawei.com> Reviewed-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
@@ -658,6 +658,14 @@ static int ra_data_block(struct inode *inode, pgoff_t index)
 	fio.page = page;
 	fio.new_blkaddr = fio.old_blkaddr = dn.data_blkaddr;
 
+	/*
+	 * don't cache encrypted data into meta inode until previous dirty
+	 * data were writebacked to avoid racing between GC and flush.
+	 */
+	f2fs_wait_on_page_writeback(page, DATA, true);
+
+	f2fs_wait_on_block_writeback(inode, dn.data_blkaddr);
+
 	fio.encrypted_page = f2fs_pagecache_get_page(META_MAPPING(sbi),
 					dn.data_blkaddr,
 					FGP_LOCK | FGP_CREAT, GFP_NOFS);
@@ -745,6 +753,8 @@ static int move_data_block(struct inode *inode, block_t bidx,
 	 */
 	f2fs_wait_on_page_writeback(page, DATA, true);
 
+	f2fs_wait_on_block_writeback(inode, dn.data_blkaddr);
+
 	err = f2fs_get_node_info(fio.sbi, dn.nid, &ni);
 	if (err)
 		goto put_out;
