f2fs: avoid GC causing encrypted file corrupted

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 6aa58d8a ("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
index a07241f..c96e7c6 100644 (file)
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -658,6 +658,14 @@ got_it:
        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;