From: James Bottomley <jejb@linux.vnet.ibm.com>
To: Bart Van Assche <bart.vanassche@sandisk.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>
Cc: "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Jens Axboe <axboe@fb.com>,
"lsf@lists.linux-foundation.org" <lsf@lists.linux-foundation.org>
Subject: Re: [Lsf] LSF/MM Schedule and improving discard support
Date: Wed, 13 Apr 2016 09:51:04 -0700 [thread overview]
Message-ID: <1460566264.2322.13.camel@linux.vnet.ibm.com> (raw)
In-Reply-To: <570E73D5.3010502@sandisk.com>
On Wed, 2016-04-13 at 09:29 -0700, Bart Van Assche wrote:
> On 04/13/2016 09:21 AM, Martin K. Petersen wrote:
> > From a filesystem/ioctl perspective, BLKDISCARD is a hint. We
> > should not be
> > rounding off or aligning anything.
>
> Hello Martin,
>
> Today if a BLKDISCARD ioctl passes a non-aligned start and/or end
> sector to the kernel then the block layer will submit invalid (non
> -aligned) REQ_DISCARD requests to the block driver the ioctl applies
> to. This is not acceptable. Does the above mean that you are
> proposing to fail such BLKDISCARD ioctls with an error code?
The answer would be of course not. discard is a hint so malformed
discard gets ignored by the device and success is returned because you
can't oblige devices to obey hints (that's why they're called hints).
However, the problem of needing a mandatory discard for scrubbing
blocks is part of the fallocate discussion, I think.
James
next prev parent reply other threads:[~2016-04-13 16:51 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-07 15:39 LSF/MM Schedule and improving discard support Bart Van Assche
2016-04-07 15:51 ` James Bottomley
2016-04-13 15:57 ` Bart Van Assche
2016-04-13 16:21 ` Martin K. Petersen
2016-04-13 16:29 ` Bart Van Assche
2016-04-13 16:43 ` [Lsf] " Martin K. Petersen
2016-04-13 16:57 ` Bart Van Assche
2016-04-13 17:13 ` Martin K. Petersen
2016-04-13 16:51 ` James Bottomley [this message]
2016-04-13 17:30 ` Darrick J. Wong
2016-04-13 22:04 ` Douglas Gilbert
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