[PATCH] f2fs: wait writeback before reading data to avoid stale encrypted block

[Jaegeuk Kim]

If background GC is running very frequently by gc_urgent, the next GC
can see unwritten data generated by the previous GC, which incurs to write
stale corrupted data in disk.

Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
---
 fs/f2fs/gc.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index a07241fb8537..49fea136a3f3 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -658,6 +658,9 @@ static int ra_data_block(struct inode *inode, pgoff_t index)
 	fio.page = page;
 	fio.new_blkaddr = fio.old_blkaddr = dn.data_blkaddr;
 
+	/* wait writeback before reading out */
+	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);
@@ -755,6 +758,9 @@ static int move_data_block(struct inode *inode, block_t bidx,
 	fio.page = page;
 	fio.new_blkaddr = fio.old_blkaddr = dn.data_blkaddr;
 
+	/* wait writeback before reading out */
+	f2fs_wait_on_block_writeback(inode, fio.old_blkaddr);
+
 	if (lfs_mode)
 		down_write(&fio.sbi->io_order_lock);
 
-- 
2.19.0.605.g01d371f741-goog