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authorMartin K. Petersen <martin.petersen@oracle.com>2017-09-27 21:38:59 -0400
committerMartin K. Petersen <martin.petersen@oracle.com>2017-10-02 22:16:25 -0400
commit77082ca503bed061f7fbda7cfd7c93beda967a41 (patch)
treedc722721e00d0a3f6ec06f379fd679a76684214b /drivers/scsi/sd.c
parent28a0bc4120d38a394499382ba21d6965a67a3703 (diff)
scsi: sd: Do not override max_sectors_kb sysfs setting
A user may lower the max_sectors_kb setting in sysfs to accommodate certain workloads. Previously we would always set the max I/O size to either the block layer default or the optional preferred I/O size reported by the device. Keep the current heuristics for the initial setting of max_sectors_kb. For subsequent invocations, only update the current queue limit if it exceeds the capabilities of the hardware. Cc: <stable@vger.kernel.org> Reported-by: Don Brace <don.brace@microsemi.com> Reviewed-by: Martin Wilck <mwilck@suse.com> Tested-by: Don Brace <don.brace@microsemi.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi/sd.c')
-rw-r--r--drivers/scsi/sd.c19
1 files changed, 14 insertions, 5 deletions
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 3d26a729825c..d175c5c5ccf8 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3107,8 +3107,6 @@ static int sd_revalidate_disk(struct gendisk *disk)
sd_read_security(sdkp, buffer);
}
- sdkp->first_scan = 0;
-
/*
* We now have all cache related info, determine how we deal
* with flush requests.
@@ -3123,7 +3121,7 @@ static int sd_revalidate_disk(struct gendisk *disk)
q->limits.max_dev_sectors = logical_to_sectors(sdp, dev_max);
/*
- * Use the device's preferred I/O size for reads and writes
+ * Determine the device's preferred I/O size for reads and writes
* unless the reported value is unreasonably small, large, or
* garbage.
*/
@@ -3137,8 +3135,19 @@ static int sd_revalidate_disk(struct gendisk *disk)
rw_max = min_not_zero(logical_to_sectors(sdp, dev_max),
(sector_t)BLK_DEF_MAX_SECTORS);
- /* Combine with controller limits */
- q->limits.max_sectors = min(rw_max, queue_max_hw_sectors(q));
+ /* Do not exceed controller limit */
+ rw_max = min(rw_max, queue_max_hw_sectors(q));
+
+ /*
+ * Only update max_sectors if previously unset or if the current value
+ * exceeds the capabilities of the hardware.
+ */
+ if (sdkp->first_scan ||
+ q->limits.max_sectors > q->limits.max_dev_sectors ||
+ q->limits.max_sectors > q->limits.max_hw_sectors)
+ q->limits.max_sectors = rw_max;
+
+ sdkp->first_scan = 0;
set_capacity(disk, logical_to_sectors(sdp, sdkp->capacity));
sd_config_write_same(sdkp);