This is partial backport of fd2ed4d252701d3bbed4cd3e3d267ad469bb832a
(only the dm_internal_suspend and dm_internal_resume functions are
backported). This is needed for further patches.
Mikulas
commit fd2ed4d252701d3bbed4cd3e3d267ad469bb832a
Author: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Date: Fri Aug 16 10:54:23 2013 -0400
dm: add statistics support
Support the collection of I/O statistics on user-defined regions of
a DM device. If no regions are defined no statistics are collected so
there isn't any performance impact. Only bio-based DM devices are
currently supported.
Each user-defined region specifies a starting sector, length and step.
Individual statistics will be collected for each step-sized area within
the range specified.
The I/O statistics counters for each step-sized area of a region are
in the same format as /sys/block/*/stat or /proc/diskstats but extra
counters (12 and 13) are provided: total time spent reading and
writing in milliseconds. All these counters may be accessed by sending
the @stats_print message to the appropriate DM device via dmsetup.
The creation of DM statistics will allocate memory via kmalloc or
fallback to using vmalloc space. At most, 1/4 of the overall system
memory may be allocated by DM statistics. The admin can see how much
memory is used by reading
/sys/module/dm_mod/parameters/stats_current_allocated_bytes
See Documentation/device-mapper/statistics.txt for more details.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Alasdair G Kergon <agk@xxxxxxxxxx>
---
drivers/md/dm.c | 33 +++++++++++++++++++++++++++++++++
drivers/md/dm.h | 3 +++
2 files changed, 36 insertions(+)
Index: linux-stable/drivers/md/dm.c
===================================================================
--- linux-stable.orig/drivers/md/dm.c 2015-06-03 16:46:06.000000000 +0200
+++ linux-stable/drivers/md/dm.c 2015-06-03 16:54:13.000000000 +0200
@@ -2680,6 +2680,39 @@ out:
return r;
}
+/*
+ * Internal suspend/resume works like userspace-driven suspend. It waits
+ * until all bios finish and prevents issuing new bios to the target drivers.
+ * It may be used only from the kernel.
+ *
+ * Internal suspend holds md->suspend_lock, which prevents interaction with
+ * userspace-driven suspend.
+ */
+
+void dm_internal_suspend(struct mapped_device *md)
+{
+ mutex_lock(&md->suspend_lock);
+ if (dm_suspended_md(md))
+ return;
+
+ down_write(&md->io_lock);
+ set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
+ up_write(&md->io_lock);
+ flush_workqueue(md->wq);
+ dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
+}
+
+void dm_internal_resume(struct mapped_device *md)
+{
+ if (dm_suspended_md(md))
+ goto done;
+
+ dm_queue_flush(md);
+
+done:
+ mutex_unlock(&md->suspend_lock);
+}
+
/*-----------------------------------------------------------------
* Event notification.
*---------------------------------------------------------------*/
Index: linux-stable/drivers/md/dm.h
===================================================================
--- linux-stable.orig/drivers/md/dm.h 2015-06-03 16:54:17.000000000 +0200
+++ linux-stable/drivers/md/dm.h 2015-06-03 16:54:32.000000000 +0200
@@ -167,6 +167,9 @@ int dm_lock_for_deletion(struct mapped_d
int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action,
unsigned cookie);
+void dm_internal_suspend(struct mapped_device *md);
+void dm_internal_resume(struct mapped_device *md);
+
int dm_io_init(void);
void dm_io_exit(void);
--
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