From: Ritesh Harjani <riteshh@linux.ibm.com>
To: Goldwyn Rodrigues <rgoldwyn@suse.com>, linux-ext4@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org, hch@infradead.org,
darrick.wong@oracle.com
Subject: Re: [PATCH v2] iomap: return partial I/O count on error in iomap_dio_bio_actor
Date: Fri, 21 Feb 2020 10:21:04 +0530 [thread overview]
Message-ID: <20200221045110.612705204E@d06av21.portsmouth.uk.ibm.com> (raw)
In-Reply-To: <20200220152355.5ticlkptc7kwrifz@fiona>
On 2/20/20 8:53 PM, Goldwyn Rodrigues wrote:
> In case of a block device error, written parameter in iomap_end()
> is zero as opposed to the amount of submitted I/O.
> Filesystems such as btrfs need to account for the I/O in ordered
> extents, even if it resulted in an error. Having (incomplete)
> submitted bytes in written gives the filesystem the amount of data
> which has been submitted before the error occurred, and the
> filesystem code can choose how to use it.
>
> The final returned error for iomap_dio_rw() is set by
> iomap_dio_complete().
>
> Partial writes in direct I/O are considered an error. So,
> ->iomap_end() using written == 0 as error must be changed
> to written < length. In this case, ext4 is the only user.
>
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
> ---
> fs/ext4/inode.c | 2 +-
> fs/iomap/direct-io.c | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index e60aca791d3f..e50e7414351a 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3475,7 +3475,7 @@ static int ext4_iomap_end(struct inode *inode, loff_t offset, loff_t length,
> * the I/O. Any blocks that may have been allocated in preparation for
> * the direct I/O will be reused during buffered I/O.
> */
> - if (flags & (IOMAP_WRITE | IOMAP_DIRECT) && written == 0)
> + if (flags & (IOMAP_WRITE | IOMAP_DIRECT) && written < length)
> return -ENOTBLK;
>
> return 0;
> diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
> index 41c1e7c20a1f..01865db1bd09 100644
> --- a/fs/iomap/direct-io.c
> +++ b/fs/iomap/direct-io.c
> @@ -264,7 +264,7 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length,
> size_t n;
> if (dio->error) {
> iov_iter_revert(dio->submit.iter, copied);
> - copied = ret = 0;
> + ret = 0;
> goto out;
> }
But if I am seeing this correctly, even after there was a dio->error
if you return copied > 0, then the loop in iomap_dio_rw will continue
for next iteration as well. Until the second time it won't copy
anything since dio->error is set and from there I guess it may return
0 which will break the loop.
Is this the correct flow? Shouldn't the while loop doing
iomap_apply in iomap_dio_rw should also break in case of
dio->error? Or did I miss anything?
-ritesh
next prev parent reply other threads:[~2020-02-21 4:51 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-20 15:23 [PATCH v2] iomap: return partial I/O count on error in iomap_dio_bio_actor Goldwyn Rodrigues
2020-02-20 17:42 ` Matthew Wilcox
2020-02-21 2:06 ` Goldwyn Rodrigues
2020-02-21 4:51 ` Ritesh Harjani [this message]
2020-02-21 12:48 ` Goldwyn Rodrigues
2020-02-25 20:53 ` Christoph Hellwig
2020-02-26 2:12 ` Damien Le Moal
2020-02-26 2:55 ` Goldwyn Rodrigues
2020-02-28 19:44 ` Goldwyn Rodrigues
2020-02-28 19:59 ` Matthew Wilcox
2020-02-28 20:35 ` Goldwyn Rodrigues
2020-03-02 13:31 ` Christoph Hellwig
2020-02-21 13:14 ` David Sterba
2020-02-20 15:24 Goldwyn Rodrigues
2020-03-19 15:08 Goldwyn Rodrigues
2020-03-20 14:05 ` Christoph Hellwig
2020-03-20 14:23 ` Josef Bacik
2020-03-20 14:35 ` Christoph Hellwig
2020-03-20 15:35 ` Goldwyn Rodrigues
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