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    Subject[PATCH AUTOSEL 4.19 032/192] f2fs: fix to data block override node segment by mistake
    Date
    From: zhengliang <zhengliang6@huawei.com>

    [ Upstream commit a0770e13c8da83bdb64738c0209ab02dd3cfff8b ]

    v4: Rearrange the previous three versions.

    The following scenario could lead to data block override by mistake.

    TASK A | TASK kworker | TASK B | TASK C
    | | |
    open | | |
    write | | |
    close | | |
    | f2fs_write_data_pages | |
    | f2fs_write_cache_pages | |
    | f2fs_outplace_write_data | |
    | f2fs_allocate_data_block (get block in seg S, | |
    | S is full, and only | |
    | have this valid data | |
    | block) | |
    | allocate_segment | |
    | locate_dirty_segment (mark S as PRE) | |
    | f2fs_submit_page_write (submit but is not | |
    | written on dev) | |
    unlink | | |
    iput_final | | |
    f2fs_drop_inode | | |
    f2fs_truncate | | |
    (not evict) | | |
    | | write_checkpoint |
    | | flush merged bio but not wait file data writeback |
    | | set_prefree_as_free (mark S as FREE) |
    | | | update NODE/DATA
    | | | allocate_segment (select S)
    | writeback done | |

    So we need to guarantee io complete before truncate inode in f2fs_drop_inode.

    Reviewed-by: Chao Yu <yuchao0@huawei.com>
    Signed-off-by: Zheng Liang <zhengliang6@huawei.com>
    Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    fs/f2fs/super.c | 4 ++++
    1 file changed, 4 insertions(+)

    diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
    index c9639ef0e8d5..7c9de4a7b794 100644
    --- a/fs/f2fs/super.c
    +++ b/fs/f2fs/super.c
    @@ -897,6 +897,10 @@ static int f2fs_drop_inode(struct inode *inode)
    sb_start_intwrite(inode->i_sb);
    f2fs_i_size_write(inode, 0);

    + f2fs_submit_merged_write_cond(F2FS_I_SB(inode),
    + inode, NULL, 0, DATA);
    + truncate_inode_pages_final(inode->i_mapping);
    +
    if (F2FS_HAS_BLOCKS(inode))
    f2fs_truncate(inode);

    --
    2.19.1
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