On 09/15/2017 11:06 PM, Liu Bo wrote:
> commit 4246a0b63bd8 ("block: add a bi_error field to struct bio")
> changed the logic of how dio read endio reports errors.
>
> For single stripe dio read, %bio->bi_status reflects the error before
> verifying checksum, and now we're updating it when data block matches
> with its checksum, while in the mismatching case, %bio->bi_status is
> not updated to relfect that.
>
> When some blocks in a file have been corrupted on disk, reading such a
> file ends up with
>
> 1) checksum errros are reported in kernel log
> 2) read(2) returns successfully with some content being 0x01.
>
> In order to fix it, we need to report its checksum mismatch error to
> the upper layer (dio layer in this case) as well.
I tested it, and now it works: even using O_DIRECT -EIO is returned if the file
is corrupted.
ghigo@venice:~/btrfs/crash-o-direct/t$ ls -li
total 16384
257 -rw-r--r-- 1 root root 16777216 Sep 15 20:51 abcd
ghigo@venice:~/btrfs/crash-o-direct/t$ date
Sat Sep 16 13:56:26 CEST 2017
ghigo@venice:~/btrfs/crash-o-direct/t$ cat abcd
cat: abcd: Input/output error
ghigo@venice:~/btrfs/crash-o-direct/t$ dmesg -T | tail -1
[Sat Sep 16 13:56:29 2017] BTRFS warning (device sdd5): csum failed root 5 ino
257 off 0 csum 0x98f94189 expected csum 0x0ab6be80 mirror 1
ghigo@venice:~/btrfs/crash-o-direct/t$ dd if=abcd iflag=direct
dd: error reading 'abcd': Input/output error
0+0 records in
0+0 records out
0 bytes copied, 0.000404156 s, 0.0 kB/s
ghigo@venice:~/btrfs/crash-o-direct/t$ dmesg -T | tail -1
[Sat Sep 16 13:56:41 2017] BTRFS warning (device sdd5): csum failed root 5 ino
257 off 0 csum 0x98f94189 expected csum 0x0ab6be80 mirror 1
>
> Signed-off-by: Liu Bo <bo.li....@oracle.com>
> Reported-by: Goffredo Baroncelli <kreij...@inwind.it>
> cc: Goffredo Baroncelli <kreij...@inwind.it>
> ---
> fs/btrfs/inode.c | 7 ++-----
> 1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 24bcd5c..a46799e 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -8267,11 +8267,8 @@ static void btrfs_endio_direct_read(struct bio *bio)
> struct btrfs_io_bio *io_bio = btrfs_io_bio(bio);
> blk_status_t err = bio->bi_status;
>
> - if (dip->flags & BTRFS_DIO_ORIG_BIO_SUBMITTED) {
> + if (dip->flags & BTRFS_DIO_ORIG_BIO_SUBMITTED)
> err = btrfs_subio_endio_read(inode, io_bio, err);
> - if (!err)
> - bio->bi_status = 0;
> - }
>
> unlock_extent(&BTRFS_I(inode)->io_tree, dip->logical_offset,
> dip->logical_offset + dip->bytes - 1);
> @@ -8279,7 +8276,7 @@ static void btrfs_endio_direct_read(struct bio *bio)
>
> kfree(dip);
>
> - dio_bio->bi_status = bio->bi_status;
> + dio_bio->bi_status = err;
> dio_end_io(dio_bio);
>
> if (io_bio->end_io)
>
--
gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it>
Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5
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