From: Goldwyn Rodrigues <rgoldwyn-l3A5Bk7waGM@public.gmane.org>
To: Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
Cc: linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
jack-IBi9RG/b67k@public.gmane.org,
linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-btrfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-xfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org,
linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
adam.manzanares-Sjgp3cTcYWE@public.gmane.org,
viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org,
Goldwyn Rodrigues <rgoldwyn-IBi9RG/b67k@public.gmane.org>
Subject: Re: [PATCH 09/10] xfs: nowait aio support
Date: Tue, 30 May 2017 11:13:29 -0500 [thread overview]
Message-ID: <f105d585-e88c-b037-9905-d0c608c609d9@suse.de> (raw)
In-Reply-To: <20170529083338.GC1899-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
On 05/29/2017 03:33 AM, Christoph Hellwig wrote:
> On Sun, May 28, 2017 at 09:38:26PM -0500, Goldwyn Rodrigues wrote:
>>
>>
>> On 05/28/2017 04:31 AM, Christoph Hellwig wrote:
>>> Despite my previous reviewed-by tag this will need another fix:
>>>
>>> xfs_file_iomap_begin needs to return EAGAIN if we don't have the extent
>>> list in memoery already. E.g. something like this:
>>>
>>> if ((flags & IOMAP_NOWAIT) && !(ip->i_d.if_flags & XFS_IFEXTENTS)) {
>>> error = -EAGAIN;
>>> goto out_unlock;
>>> }
>>>
>>> right after locking the ilock.
>>>
>>
>> I am not sure if it is right to penalize the application to write to
>> file which has been freshly opened (and is the first one to open). It
>> basically means extent maps needs to be read from disk. Do you see a
>> reason it would have a non-deterministic wait if it is the only user? I
>> understand the block layer can block if it has too many requests though.
>
> For either a read or a write we might have to read in the extent list
> (note that for few enough extents they are stored in the inode and
> we won't have to), in which case the call will block and by the
> semantics you define we'll need to return -EAGAIN.
Yes, that is right. I will include it in.
>
> Btw, can you write a small blurb up for the man page to document these
> ѕemantics in man-page like language?
>
Yes, but which man page would it belong to?
Should it be a subsection of errors in io_getevents/io_submit. We don't
want to add ERRORS to io_getevents() because it would be the return
value of the io_getevents call, and not the ones in the iocb structure.
Should it be a new man page, say for iocb(7/8)?
--
Goldwyn
next prev parent reply other threads:[~2017-05-30 16:13 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-24 16:41 [PATCH 0/10 v9] No wait AIO Goldwyn Rodrigues
2017-05-24 16:41 ` [PATCH 01/10] fs: Separate out kiocb flags setup based on RWF_* flags Goldwyn Rodrigues
2017-05-25 8:16 ` Jan Kara
2017-05-24 16:41 ` [PATCH 02/10] fs: Introduce filemap_range_has_page() Goldwyn Rodrigues
2017-05-25 8:25 ` Jan Kara
[not found] ` <20170524164150.9492-1-rgoldwyn-l3A5Bk7waGM@public.gmane.org>
2017-05-24 16:41 ` [PATCH 03/10] fs: Use RWF_* flags for AIO operations Goldwyn Rodrigues
2017-05-25 8:27 ` Jan Kara
2017-05-24 16:41 ` [PATCH 05/10] fs: return if direct write will trigger writeback Goldwyn Rodrigues
2017-05-25 8:32 ` Jan Kara
2017-05-28 9:27 ` [PATCH 0/10 v9] No wait AIO Christoph Hellwig
2017-05-29 2:38 ` Goldwyn Rodrigues
2017-05-29 8:32 ` Christoph Hellwig
2017-05-24 16:41 ` [PATCH 04/10] fs: Introduce RWF_NOWAIT Goldwyn Rodrigues
2017-05-25 8:30 ` Jan Kara
2017-05-24 16:41 ` [PATCH 06/10] fs: Introduce IOMAP_NOWAIT Goldwyn Rodrigues
2017-05-25 8:33 ` Jan Kara
2017-05-24 16:41 ` [PATCH 07/10] fs: return on congested block device Goldwyn Rodrigues
2017-05-24 16:41 ` [PATCH 08/10] ext4: nowait aio support Goldwyn Rodrigues
2017-05-24 16:41 ` [PATCH 09/10] xfs: " Goldwyn Rodrigues
2017-05-24 16:49 ` Darrick J. Wong
[not found] ` <20170524164150.9492-10-rgoldwyn-l3A5Bk7waGM@public.gmane.org>
2017-05-28 9:31 ` Christoph Hellwig
2017-05-29 2:38 ` Goldwyn Rodrigues
2017-05-29 8:21 ` Jan Kara
2017-05-29 8:33 ` Christoph Hellwig
[not found] ` <20170529083338.GC1899-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2017-05-30 16:13 ` Goldwyn Rodrigues [this message]
2017-05-31 8:51 ` Jan Kara
2017-05-24 16:41 ` [PATCH 10/10] btrfs: " Goldwyn Rodrigues
-- strict thread matches above, loose matches on Subject: below --
2017-06-15 15:59 [PATCH 0/10 v12] No wait AIO Goldwyn Rodrigues
2017-06-15 16:00 ` [PATCH 09/10] xfs: nowait aio support Goldwyn Rodrigues
2017-06-06 11:19 [PATCH 0/10 v11] No wait AIO Goldwyn Rodrigues
2017-06-06 11:19 ` [PATCH 09/10] xfs: nowait aio support Goldwyn Rodrigues
2017-06-05 5:35 [PATCH 0/10 v10] No wait AIO Goldwyn Rodrigues
2017-06-05 5:35 ` [PATCH 09/10] xfs: nowait aio support Goldwyn Rodrigues
2017-05-11 19:17 [PATCH 0/10 v8] No wait AIO Goldwyn Rodrigues
2017-05-11 19:17 ` [PATCH 09/10] xfs: nowait aio support Goldwyn Rodrigues
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