From: Fam Zheng <famz@redhat.com>
To: Eric Farman <farman@linux.vnet.ibm.com>
Cc: kwolf@redhat.com, linux-scsi@vger.kernel.org,
qemu-block@nongnu.org, qemu-devel@nongnu.org, mreitz@redhat.com,
pbonzini@redhat.com
Subject: Re: [Qemu-devel] [RFC PATCH 0/3] scsi-generic and BLKSECTGET
Date: Tue, 17 Jan 2017 15:08:18 +0800 [thread overview]
Message-ID: <20170117070818.GE21563@lemon.Home> (raw)
In-Reply-To: <20170116211201.46601-1-farman@linux.vnet.ibm.com>
On Mon, 01/16 22:11, Eric Farman wrote:
> (cc'ing linux-scsi for the cover-letter; patches only to QEMU lists.)
>
> In the Linux kernel, I see two (three) places where the BLKSECTGET ioctl is
> handled:
>
> (1) block/(compat_)ioctl.c -- (compat_)blkdev_ioctl
> (2) drivers/scsi/sg.c -- sg_ioctl
>
> The former has been around forever[1], and returns a short value measured in
> sectors. A sector is generally assumed to be 512 bytes.
>
> The latter has been around for slightly less than forever[2], and returns an
> int that measures the value in bytes. A change to return the block count
> was brought up a few years ago[3] and nacked.
>
> As a convenient example, if I use the blockdev tool to drive the ioctl to a
> SCSI disk and its scsi-generic equivalent, I get different results:
Fun! :-/
The patch looks correct but I don't like how it is written a lot, but still
thanks for bringing it up so we won't be bitten in the future, and your detailed
explanation is much appreciated!
Fam
WARNING: multiple messages have this Message-ID (diff)
From: Fam Zheng <famz@redhat.com>
To: Eric Farman <farman@linux.vnet.ibm.com>
Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, kwolf@redhat.com,
pbonzini@redhat.com, linux-scsi@vger.kernel.org,
mreitz@redhat.com
Subject: Re: [Qemu-devel] [RFC PATCH 0/3] scsi-generic and BLKSECTGET
Date: Tue, 17 Jan 2017 15:08:18 +0800 [thread overview]
Message-ID: <20170117070818.GE21563@lemon.Home> (raw)
In-Reply-To: <20170116211201.46601-1-farman@linux.vnet.ibm.com>
On Mon, 01/16 22:11, Eric Farman wrote:
> (cc'ing linux-scsi for the cover-letter; patches only to QEMU lists.)
>
> In the Linux kernel, I see two (three) places where the BLKSECTGET ioctl is
> handled:
>
> (1) block/(compat_)ioctl.c -- (compat_)blkdev_ioctl
> (2) drivers/scsi/sg.c -- sg_ioctl
>
> The former has been around forever[1], and returns a short value measured in
> sectors. A sector is generally assumed to be 512 bytes.
>
> The latter has been around for slightly less than forever[2], and returns an
> int that measures the value in bytes. A change to return the block count
> was brought up a few years ago[3] and nacked.
>
> As a convenient example, if I use the blockdev tool to drive the ioctl to a
> SCSI disk and its scsi-generic equivalent, I get different results:
Fun! :-/
The patch looks correct but I don't like how it is written a lot, but still
thanks for bringing it up so we won't be bitten in the future, and your detailed
explanation is much appreciated!
Fam
next prev parent reply other threads:[~2017-01-17 7:08 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-16 21:11 [RFC PATCH 0/3] scsi-generic and BLKSECTGET Eric Farman
2017-01-16 21:11 ` [Qemu-devel] " Eric Farman
2017-01-16 21:11 ` [Qemu-devel] [PATCH 1/3] hw/scsi: Fix debug message of cdb structure in scsi-generic Eric Farman
2017-01-16 21:12 ` [Qemu-devel] [PATCH 2/3] block: Fix target variable of BLKSECTGET ioctl Eric Farman
2017-01-16 21:12 ` [Qemu-devel] [PATCH 3/3] block: get max_transfer limit for char (scsi-generic) devices Eric Farman
2017-01-17 7:04 ` Fam Zheng
2017-01-17 14:49 ` Eric Farman
2017-01-17 7:08 ` Fam Zheng [this message]
2017-01-17 7:08 ` [Qemu-devel] [RFC PATCH 0/3] scsi-generic and BLKSECTGET Fam Zheng
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