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* [PATCH] scsi:Prevent deletion of SCSI block device in use
@ 2016-09-13 16:38 Gurunath, Vasundhara
  2016-09-13 17:17 ` James Bottomley
  2016-09-13 18:25 ` Ewan D. Milne
  0 siblings, 2 replies; 8+ messages in thread
From: Gurunath, Vasundhara @ 2016-09-13 16:38 UTC (permalink / raw)
  To: jejb, martin.petersen
  Cc: linux-scsi, paulose.kuriakose.arackal, jasminder.kaur, Gurunath,
	Vasundhara

From: "Gurunath, Vasundhara" <vasundhara.gurunath@hpe.com>

SCSI block device can be removed, using write to sysfs
delete file as below:
echo 1 > /sys/block/sdX/device/delete
If the device is in use by applications, or part of
system configuration such as boot device, removal can
result in application disruptions or system down time.

An additional write option ? is added to SCSI sysfs
interface as below, in order to prevent accidental
deletion of devices in use.
echo ? > /sys/block/sdX/device/delete

In the absence of any usage, this option proceeds with
device deletion.  If the device is open, deletion is
prevented, and active Open and IO counts at the time of
deletion is logged. Information logged during latest
delete attempt can be obtained by issuing a read to the
delete file as below:
cat  /sys/block/sdX/device/delete

Signed-off-by: Vasundhara Gurunath <vasundhara.gurunath@hpe.com>
---
 drivers/scsi/scsi_sysfs.c  | 52 +++++++++++++++++++++++++++++++++++++++++++++-
 drivers/scsi/sd.c          |  4 ++++
 include/scsi/scsi_device.h |  2 ++
 3 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 0734927..b0cbfbb 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -12,6 +12,8 @@
 #include <linux/blkdev.h>
 #include <linux/device.h>
 #include <linux/pm_runtime.h>
+#include <linux/time.h>
+#include <linux/timer.h>
 
 #include <scsi/scsi.h>
 #include <scsi/scsi_device.h>
@@ -457,6 +459,8 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work)
 	kfree(sdev->vpd_pg83);
 	kfree(sdev->vpd_pg80);
 	kfree(sdev->inquiry);
+	if (sdev->delete_msg_buf != NULL)
+		kfree(sdev->delete_msg_buf);
 	kfree(sdev);
 
 	if (parent)
@@ -709,11 +713,57 @@ static ssize_t
 sdev_store_delete(struct device *dev, struct device_attribute *attr,
 		  const char *buf, size_t count)
 {
+	struct scsi_device *sdev = to_scsi_device(dev);
+	struct timeval tv;
+	struct tm tms;
+
+	if (buf[0] == '?')  {
+		if (sdev->usage_count) {
+			/*
+			* Buffer to hold I/O statistics on delete attempt.
+			*/
+			if (sdev->delete_msg_buf == NULL) {
+				sdev->delete_msg_buf =
+				kmalloc(128, GFP_KERNEL);
+				memset(sdev->delete_msg_buf, 0, 128);
+			}
+			do_gettimeofday(&tv);
+			time_to_tm(tv.tv_sec, 0, &tms);
+			sprintf(sdev->delete_msg_buf,
+				"Last delete attempt: %d:%d:%ld %02d:%02d\n"
+				"Open Count : %d\n"
+				"IO Active Count : %d\n"
+				"IO Done Count : %d\n",
+				tms.tm_mday, tms.tm_mon + 1,
+				tms.tm_year + 1900,
+				tms.tm_hour, tms.tm_min,
+				sdev->usage_count,
+				sdev->iorequest_cnt.counter,
+				sdev->iodone_cnt.counter);
+
+			return count;
+		}
+	}
+
+
 	if (device_remove_file_self(dev, attr))
 		scsi_remove_device(to_scsi_device(dev));
 	return count;
 };
-static DEVICE_ATTR(delete, S_IWUSR, NULL, sdev_store_delete);
+
+static ssize_t sdev_show_delete(struct device *dev,
+	struct device_attribute *attr, char *buf) {
+
+	struct scsi_device *sdev = to_scsi_device(dev);
+
+	if (sdev->delete_msg_buf != NULL)
+		return sprintf(buf, "%s", sdev->delete_msg_buf);
+	else
+		return 0;
+}
+
+static DEVICE_ATTR(delete, S_IRUGO | S_IWUSR,
+	sdev_show_delete, sdev_store_delete);
 
 static ssize_t
 store_state_field(struct device *dev, struct device_attribute *attr,
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index d3e852a..67d3406 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1235,6 +1235,7 @@ static int sd_open(struct block_device *bdev, fmode_t mode)
 		if (scsi_block_when_processing_errors(sdev))
 			scsi_set_medium_removal(sdev, SCSI_REMOVAL_PREVENT);
 	}
+	sdev->usage_count = sdkp->openers.counter;
 
 	return 0;
 
@@ -1267,6 +1268,7 @@ static void sd_release(struct gendisk *disk, fmode_t mode)
 		if (scsi_block_when_processing_errors(sdev))
 			scsi_set_medium_removal(sdev, SCSI_REMOVAL_ALLOW);
 	}
+	sdev->usage_count = sdkp->openers.counter;
 
 	/*
 	 * XXX and what if there are packets in flight and this close()
@@ -3082,6 +3084,8 @@ static int sd_probe(struct device *dev)
 	atomic_set(&sdkp->openers, 0);
 	atomic_set(&sdkp->device->ioerr_cnt, 0);
 
+	sdp->usage_count = sdkp->openers.counter;
+
 	if (!sdp->request_queue->rq_timeout) {
 		if (sdp->type != TYPE_MOD)
 			blk_queue_rq_timeout(sdp->request_queue, SD_TIMEOUT);
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 8a95631..ab79675 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -208,6 +208,8 @@ struct scsi_device {
 
 	unsigned char		access_state;
 	enum scsi_device_state sdev_state;
+	char                    *delete_msg_buf;
+	int                     usage_count;
 	unsigned long		sdev_data[0];
 } __attribute__((aligned(sizeof(unsigned long))));
 
-- 
1.8.3.1


^ permalink raw reply related	[flat|nested] 8+ messages in thread
* [PATCH] scsi:Prevent deletion of SCSI block device in use
@ 2016-09-19  9:11 Gurunath, Vasundhara (STSD)
  2016-09-19 12:55 ` James Bottomley
  0 siblings, 1 reply; 8+ messages in thread
From: Gurunath, Vasundhara (STSD) @ 2016-09-19  9:11 UTC (permalink / raw)
  To: James Bottomley, martin.petersen
  Cc: linux-scsi, Arackal, Paulose Kuriakose (STSD), Kaur, Jasminder (STSD)


James Bottomley <jejb@linux.vnet.ibm.com> wrote: 

>> From: "Gurunath, Vasundhara" <vasundhara.gurunath@hpe.com>
>>
>> SCSI block device can be removed, using write to sysfs delete file as
>> below:
>> echo 1 > /sys/block/sdX/device/delete If the device is in use by 
>> applications, or part of system configuration such as boot device, 
>> removal can result in application disruptions or system down time.
> >
>> An additional write option ? is added to SCSI sysfs interface as 
>> below, in order to prevent accidental deletion of devices in use.
>> echo ? > /sys/block/sdX/device/delete
>>
>> In the absence of any usage, this option proceeds with device 
>> deletion.  If the device is open, deletion is prevented, and active 
>> Open and IO counts at the time of deletion is logged. Information 
>> logged during latest delete attempt can be obtained by issuing a read 
>> to the delete file as below:
>> cat  /sys/block/sdX/device/delete

>OK, so I'm not too keen on this because our entire system is (finally) designed to be hot plug, so echoing 1 to delete simulates a hotplug event, and they >can come in at any time.

>Can you elaborate on why this is necessary?  Right at the moment, only 
>root is allowed to write to this file and cause a deletion ... plus the file is pretty >hard to find, buried as it is in sysfs;  So I would have thought it was pretty safe from accidental misuse; why does it need additional protection?

Some of the requests we got for such checks were from use cases on large system configurations with several LUNs.
The new changes do not disturb existing interfaces. Writes to the "delete" sysfs file such as a "1", as advertised in some distributions like RedHat today, will continue to delete the LUN. However we thought an option to check usages during delete can complement existing interfaces. 
 
The new changes get activated only when one wants to receive alerts on any lingering usages, and writes a "?" to delete the LUN.
A delete script can write "?" to sysfs delete files in bulk, while most LUNs get removed in the first attempt, the usages can be investigated if any LUNs remain with active usage counts. 

Hopefully overhead of these changes is minimal, it is few additional checks on usage counts and the log.
New changes get active only in delete context and doesn't get into I/O paths.

-Vasundhara



^ permalink raw reply	[flat|nested] 8+ messages in thread
* [PATCH] scsi:Prevent deletion of SCSI block device in use
@ 2016-08-19 10:36 Vasundhara Gurunath
  2016-08-22 15:36   ` kbuild test robot
  0 siblings, 1 reply; 8+ messages in thread
From: Vasundhara Gurunath @ 2016-08-19 10:36 UTC (permalink / raw)
  To: jejb, martin.petersen
  Cc: linux-scsi, linux-kernel, jasminder.kaur,
	paulose.kuriakose.arackal, Vasundhara Gurunath

SCSI block device can be removed, using write to sysfs delete file as below:
echo 1 > /sys/block/sdX/device/delete
If the device is in use by applications, or part of system configuration
such as boot device, removal can result in application disruptions or
system down time.

An additional write option ? is added to SCSI sysfs interface as below,
in order to prevent accidental deletion of devices in use.
echo ? > /sys/block/sdX/device/delete

In the absence of any usage, this option proceeds with device deletion.
If the device is open, deletion is prevented, and active Open and IO
counts at the time of deletion is logged. Information logged during latest
delete attempt can be obtained by issuing a read to the delete file as below:
cat  /sys/block/sdX/device/delete

Signed-off-by: Vasundhara Gurunath <vasundhara.gurunath@hpe.com>
---
 drivers/scsi/scsi_sysfs.c  | 51 +++++++++++++++++++++++++++++++++++++++++++++-
 drivers/scsi/sd.c          |  5 ++++-
 include/scsi/scsi_device.h |  2 ++
 3 files changed, 56 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 0734927..716b22a 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -12,6 +12,9 @@
 #include <linux/blkdev.h>
 #include <linux/device.h>
 #include <linux/pm_runtime.h>
+#include <linux/time.h>
+#include <linux/timer.h>
+
 
 #include <scsi/scsi.h>
 #include <scsi/scsi_device.h>
@@ -457,6 +460,9 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work)
 	kfree(sdev->vpd_pg83);
 	kfree(sdev->vpd_pg80);
 	kfree(sdev->inquiry);
+	if (sdev->delete_msg_buf != NULL)
+		kfree(sdev->delete_msg_buf);
+
 	kfree(sdev);
 
 	if (parent)
@@ -709,11 +715,54 @@ static ssize_t
 sdev_store_delete(struct device *dev, struct device_attribute *attr,
 		  const char *buf, size_t count)
 {
+	struct scsi_device *sdev = to_scsi_device(dev);
+	struct timeval tv;
+	struct tm tms;
+
+	if (buf[0] == '?')  {
+		if (sdev->usage_count) {
+			/*
+			 * Buffer to hold I/O statistics on delete attempt.
+			 */
+			if (sdev->delete_msg_buf == NULL) {
+				sdev->delete_msg_buf =
+				kmalloc(128, GFP_KERNEL);
+				memset(sdev->delete_msg_buf, 0, 128);
+			}
+			do_gettimeofday(&tv);
+			time_to_tm(tv.tv_sec, 0, &tms);
+			sprintf(sdev->delete_msg_buf,
+				"Last delete attempt: %d:%d:%d %02d:%02d\n"
+				"Open Count : %d\n"
+				"IO Active Count : %d\n"
+				"IO Done Count : %d\n",
+				tms.tm_mday, tms.tm_mon + 1,
+				tms.tm_year + 1900,
+				tms.tm_hour, tms.tm_min,
+				sdev->usage_count,
+				sdev->iorequest_cnt.counter,
+				sdev->iodone_cnt.counter);
+
+				return count;
+			}
+		}
+
 	if (device_remove_file_self(dev, attr))
 		scsi_remove_device(to_scsi_device(dev));
 	return count;
 };
-static DEVICE_ATTR(delete, S_IWUSR, NULL, sdev_store_delete);
+
+static ssize_t sdev_show_delete(struct device *dev,
+		struct device_attribute *attr, char *buf) {
+
+	struct scsi_device *sdev = to_scsi_device(dev);
+	if (sdev->delete_msg_buf != NULL)
+		return sprintf(buf, "%s", sdev->delete_msg_buf);
+	else
+		return 0;
+}
+static DEVICE_ATTR(delete, S_IRUGO | S_IWUSR, sdev_show_delete,
+			 sdev_store_delete);
 
 static ssize_t
 store_state_field(struct device *dev, struct device_attribute *attr,
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index d3e852a..d5cf25c 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1235,6 +1235,7 @@ static int sd_open(struct block_device *bdev, fmode_t mode)
 		if (scsi_block_when_processing_errors(sdev))
 			scsi_set_medium_removal(sdev, SCSI_REMOVAL_PREVENT);
 	}
+	sdev->usage_count = sdkp->openers.counter;
 
 	return 0;
 
@@ -1267,7 +1268,7 @@ static void sd_release(struct gendisk *disk, fmode_t mode)
 		if (scsi_block_when_processing_errors(sdev))
 			scsi_set_medium_removal(sdev, SCSI_REMOVAL_ALLOW);
 	}
-
+	sdev->usage_count = sdkp->openers.counter;
 	/*
 	 * XXX and what if there are packets in flight and this close()
 	 * XXX is followed by a "rmmod sd_mod"?
@@ -3082,6 +3083,8 @@ static int sd_probe(struct device *dev)
 	atomic_set(&sdkp->openers, 0);
 	atomic_set(&sdkp->device->ioerr_cnt, 0);
 
+	sdp->usage_count = sdkp->openers.counter;
+
 	if (!sdp->request_queue->rq_timeout) {
 		if (sdp->type != TYPE_MOD)
 			blk_queue_rq_timeout(sdp->request_queue, SD_TIMEOUT);
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 8a95631..ab79675 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -208,6 +208,8 @@ struct scsi_device {
 
 	unsigned char		access_state;
 	enum scsi_device_state sdev_state;
+	char                    *delete_msg_buf;
+	int                     usage_count;
 	unsigned long		sdev_data[0];
 } __attribute__((aligned(sizeof(unsigned long))));
 
-- 
1.8.3.1

^ permalink raw reply related	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2016-09-19 12:56 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-09-13 16:38 [PATCH] scsi:Prevent deletion of SCSI block device in use Gurunath, Vasundhara
2016-09-13 17:17 ` James Bottomley
2016-09-13 18:25 ` Ewan D. Milne
  -- strict thread matches above, loose matches on Subject: below --
2016-09-19  9:11 Gurunath, Vasundhara (STSD)
2016-09-19 12:55 ` James Bottomley
2016-08-19 10:36 Vasundhara Gurunath
2016-08-22 15:36 ` kbuild test robot
2016-08-22 15:36   ` kbuild test robot

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