lkml.org 
[lkml]   [2018]   [Oct]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] f2fs: avoid GC causing encrypted file corrupted
From
Date
ping...

On 2018/9/18 20:39, Yunlong Song wrote:
> 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>
> ---
> fs/f2fs/gc.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index a4c1a41..c55fb62 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -641,6 +641,14 @@ 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);
> @@ -723,6 +731,8 @@ static void 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;

--
Thanks,
Yunlong Song


\
 
 \ /
  Last update: 2018-10-24 10:08    [W:0.064 / U:3.204 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site