[3.19.y-ckt stable] Patch "sd: Fix maximum I/O size for BLOCK_PC requests" has been added to staging queue
Kamal Mostafa
kamal at canonical.com
Mon Sep 21 22:26:21 UTC 2015
This is a note to let you know that I have just added a patch titled
sd: Fix maximum I/O size for BLOCK_PC requests
to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree
which can be found at:
http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue
This patch is scheduled to be released in version 3.19.8-ckt7.
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Kamal
------
>From e1e49ffe075476c25bdb48f40e586d2c508fd2e9 Mon Sep 17 00:00:00 2001
From: "Martin K. Petersen" <martin.petersen at oracle.com>
Date: Tue, 23 Jun 2015 12:13:59 -0400
Subject: sd: Fix maximum I/O size for BLOCK_PC requests
commit 4f258a46346c03fa0bbb6199ffaf4e1f9f599660 upstream.
Commit bcdb247c6b6a ("sd: Limit transfer length") clamped the maximum
size of an I/O request to the MAXIMUM TRANSFER LENGTH field in the BLOCK
LIMITS VPD. This had the unfortunate effect of also limiting the maximum
size of non-filesystem requests sent to the device through sg/bsg.
Avoid using blk_queue_max_hw_sectors() and set the max_sectors queue
limit directly.
Also update the comment in blk_limits_max_hw_sectors() to clarify that
max_hw_sectors defines the limit for the I/O controller only.
Signed-off-by: Martin K. Petersen <martin.petersen at oracle.com>
Reported-by: Brian King <brking at linux.vnet.ibm.com>
Tested-by: Brian King <brking at linux.vnet.ibm.com>
Signed-off-by: James Bottomley <JBottomley at Odin.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
block/blk-settings.c | 4 ++--
drivers/scsi/sd.c | 6 +++---
2 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 12600bf..e0057d0 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -241,8 +241,8 @@ EXPORT_SYMBOL(blk_queue_bounce_limit);
* Description:
* Enables a low level driver to set a hard upper limit,
* max_hw_sectors, on the size of requests. max_hw_sectors is set by
- * the device driver based upon the combined capabilities of I/O
- * controller and storage device.
+ * the device driver based upon the capabilities of the I/O
+ * controller.
*
* max_sectors is a soft limit imposed by the block layer for
* filesystem type requests. This value can be overridden on a
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 7f71d7d..c80e1fe 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2794,9 +2794,9 @@ static int sd_revalidate_disk(struct gendisk *disk)
max_xfer = sdkp->max_xfer_blocks;
max_xfer <<= ilog2(sdp->sector_size) - 9;
- max_xfer = min_not_zero(queue_max_hw_sectors(sdkp->disk->queue),
- max_xfer);
- blk_queue_max_hw_sectors(sdkp->disk->queue, max_xfer);
+ sdkp->disk->queue->limits.max_sectors =
+ min_not_zero(queue_max_hw_sectors(sdkp->disk->queue), max_xfer);
+
set_capacity(disk, sdkp->capacity);
sd_config_write_same(sdkp);
kfree(buffer);
--
1.9.1
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