From: Bart Van Assche <bart.vanassche@sandisk.com>
To: mchristi@redhat.com, linux-scsi@vger.kernel.org,
target-devel@vger.kernel.org, socketpair@gmail.com
Cc: stable@vger.kernel.org
Subject: Re: [PATCH 2/2] target: fix max discard sectors calculation
Date: Mon, 16 May 2016 11:57:42 -0700 [thread overview]
Message-ID: <573A1826.3050007@sandisk.com> (raw)
In-Reply-To: <1463424410-17196-3-git-send-email-mchristi@redhat.com>
On 05/16/2016 11:46 AM, mchristi@redhat.com wrote:
> diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
> index a4046ca..3f9f304 100644
> --- a/drivers/target/target_core_device.c
> +++ b/drivers/target/target_core_device.c
> @@ -826,8 +826,8 @@ bool target_configure_unmap_from_queue(struct se_dev_attrib *attrib,
> - attrib->max_unmap_lba_count = (q->limits.max_discard_sectors << 9) /
> - block_size;
> + attrib->max_unmap_lba_count =
> + ((u64)q->limits.max_discard_sectors << 9) / block_size;
Hello Mike,
That's a good catch. But seeing this patch makes me wonder whether this
patch introduces a 64-bit division? If so, I'm afraid this patch will
make 32-bit users unhappy. Have you considered to use do_div() or >>
(ilog2(block_size) - 9) instead? For the latter alternative no 64-bit
cast is needed.
Thanks,
Bart.
WARNING: multiple messages have this Message-ID (diff)
From: Bart Van Assche <bart.vanassche@sandisk.com>
To: <mchristi@redhat.com>, <linux-scsi@vger.kernel.org>,
<target-devel@vger.kernel.org>, <socketpair@gmail.com>
Cc: <stable@vger.kernel.org>
Subject: Re: [PATCH 2/2] target: fix max discard sectors calculation
Date: Mon, 16 May 2016 11:57:42 -0700 [thread overview]
Message-ID: <573A1826.3050007@sandisk.com> (raw)
In-Reply-To: <1463424410-17196-3-git-send-email-mchristi@redhat.com>
On 05/16/2016 11:46 AM, mchristi@redhat.com wrote:
> diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
> index a4046ca..3f9f304 100644
> --- a/drivers/target/target_core_device.c
> +++ b/drivers/target/target_core_device.c
> @@ -826,8 +826,8 @@ bool target_configure_unmap_from_queue(struct se_dev_attrib *attrib,
> - attrib->max_unmap_lba_count = (q->limits.max_discard_sectors << 9) /
> - block_size;
> + attrib->max_unmap_lba_count =
> + ((u64)q->limits.max_discard_sectors << 9) / block_size;
Hello Mike,
That's a good catch. But seeing this patch makes me wonder whether this
patch introduces a 64-bit division? If so, I'm afraid this patch will
make 32-bit users unhappy. Have you considered to use do_div() or >>
(ilog2(block_size) - 9) instead? For the latter alternative no 64-bit
cast is needed.
Thanks,
Bart.
next prev parent reply other threads:[~2016-05-16 18:57 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-16 18:46 [PATCH 0/2] fix max discard sectors calculation mchristi
2016-05-16 18:46 ` [PATCH 1/2] scsi: " mchristi
2016-05-16 22:44 ` Bart Van Assche
2016-05-16 22:44 ` Bart Van Assche
2016-05-17 3:46 ` Mike Christie
2016-05-16 18:46 ` [PATCH 2/2] target: " mchristi
2016-05-16 18:57 ` Bart Van Assche [this message]
2016-05-16 18:57 ` Bart Van Assche
2016-05-16 19:00 ` Mike Christie
2016-05-16 19:02 ` Martin K. Petersen
2016-05-16 19:02 ` Martin K. Petersen
2016-05-17 18:16 ` Bart Van Assche
2016-05-17 18:16 ` Bart Van Assche
2016-05-17 21:49 ` Mike Christie
2016-05-18 16:56 ` Bart Van Assche
2016-05-18 16:56 ` Bart Van Assche
2016-05-18 17:17 ` Mike Christie
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