[PATCH] md: Support suspending of IO to regions of an md array
This allows user-space to access data safely. This is needed for raid5
reshape as user-space needs to take a backup of the first few stripes before
allowing reshape to commence.
It will also be useful in cluster-aware raid1 configurations so that all
cluster members can leave a section of the array untouched while a
resync/recovery happens.
A 'start' and 'end' of the suspended range are written to 2 sysfs attributes.
Note that only one range can be suspended at a time.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/raid/md_k.h b/include/linux/raid/md_k.h
index 002ee631..c0d3097 100644
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -151,6 +151,10 @@
sector_t resync_mismatches; /* count of sectors where
* parity/replica mismatch found
*/
+
+ /* allow user-space to request suspension of IO to regions of the array */
+ sector_t suspend_lo;
+ sector_t suspend_hi;
/* if zero, use the system-wide default */
int sync_speed_min;
int sync_speed_max;