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    Subject[PATCH AUTOSEL 4.20 085/304] f2fs: avoid GC causing encrypted file corrupted
    Date
    From: Yunlong Song <yunlong.song@huawei.com>

    [ Upstream commit 9bf1a3f73927492c8be127b642197125e9d52be8 ]

    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>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    fs/f2fs/gc.c | 10 ++++++++++
    1 file changed, 10 insertions(+)

    diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
    index a07241fb8537..c96e7c6354ef 100644
    --- 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;
    --
    2.19.1
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