Messages in this thread | | | Date | Tue, 18 Sep 2018 11:17:05 -0700 | From | Jaegeuk Kim <> | Subject | Re: [PATCH] f2fs: avoid GC causing encrypted file corrupted |
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On 09/18, 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 |
segment 2 blkaddr = B?
> > 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,
C of ?
> 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.
move_data_block() checks PageUptodate() so it won't get garbage, yes? So, does ra_data_block need to check PageUptodate?
> > 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; > -- > 1.8.5.2
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