From: Al Viro <viro@ZenIV.linux.org.uk>
To: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: axboe@kernel.dk, hch@lst.de, jack@suse.cz,
akpm@linux-foundation.org, linux-block@vger.kernel.org,
Goldwyn Rodrigues <rgoldwyn@suse.com>
Subject: Re: [PATCH 05/10] fs: return if direct I/O will trigger writeback
Date: Mon, 19 Jun 2017 17:44:27 +0100 [thread overview]
Message-ID: <20170619164427.GF10672@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20170619163348.15542-6-rgoldwyn@suse.de>
On Mon, Jun 19, 2017 at 11:33:43AM -0500, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@suse.com>
>
> Find out if the I/O will trigger a wait due to writeback. If yes,
> return -EAGAIN.
>
> Return -EINVAL for buffered AIO: there are multiple causes of
> delay such as page locks, dirty throttling logic, page loading
> from disk etc. which cannot be taken care of.
>
I don't believe that generic_file_read_iter() is sufficient. Consider
ext4_file_read_iter() -> ext4_dax_read_iter():
static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
struct inode *inode = file_inode(iocb->ki_filp);
ssize_t ret;
inode_lock_shared(inode);
IOW, your ext4 patch is missing a chunk. I hadn't checked xfs one...
next prev parent reply other threads:[~2017-06-19 16:44 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-19 16:33 [PATCH 0/10 v13] merge request: No wait AIO Goldwyn Rodrigues
2017-06-19 16:33 ` [PATCH 01/10] fs: Separate out kiocb flags setup based on RWF_* flags Goldwyn Rodrigues
2017-06-19 16:33 ` [PATCH 02/10] fs: Introduce filemap_range_has_page() Goldwyn Rodrigues
2017-06-19 16:33 ` [PATCH 03/10] fs: Use RWF_* flags for AIO operations Goldwyn Rodrigues
2017-06-19 16:33 ` [PATCH 04/10] fs: Introduce RWF_NOWAIT and FMODE_AIO_NOWAIT Goldwyn Rodrigues
2017-06-19 16:33 ` [PATCH 05/10] fs: return if direct I/O will trigger writeback Goldwyn Rodrigues
2017-06-19 16:44 ` Al Viro [this message]
2017-06-19 16:33 ` [PATCH 06/10] fs: Introduce IOMAP_NOWAIT Goldwyn Rodrigues
2017-06-19 16:33 ` [PATCH 07/10] block: return on congested block device Goldwyn Rodrigues
2017-06-19 16:33 ` [PATCH 08/10] ext4: nowait aio support Goldwyn Rodrigues
2017-06-19 16:33 ` [PATCH 09/10] xfs: " Goldwyn Rodrigues
2017-06-19 16:33 ` [PATCH 10/10] btrfs: " Goldwyn Rodrigues
2017-06-19 23:15 ` [PATCH 0/10 v13] merge request: No wait AIO Jens Axboe
2017-06-19 23:20 ` Goldwyn Rodrigues
2017-06-19 23:34 ` Al Viro
2017-06-19 23:36 ` Jens Axboe
2017-06-20 0:24 ` Al Viro
2017-06-20 7:20 ` Christoph Hellwig
2017-06-20 11:53 ` Goldwyn Rodrigues
-- strict thread matches above, loose matches on Subject: below --
2017-06-20 12:05 [PATCH 0/10 v14] " Goldwyn Rodrigues
2017-06-20 12:05 ` [PATCH 05/10] fs: return if direct I/O will trigger writeback Goldwyn Rodrigues
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