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authorNeilBrown <neilb@suse.de>2011-12-23 10:17:51 +1100
committerNeilBrown <neilb@suse.de>2011-12-23 10:17:51 +1100
commit2d78f8c451785f030ac1676a18691896b59c69d8 (patch)
tree4dfe69115b2ca2fb8be2a671e7c8399c3925fcb9 /include/linux/raid
parentb8321b68d1445f308324517e45fb0a5c2b48e271 (diff)
md: create externally visible flags for supporting hot-replace.
hot-replace is a feature being added to md which will allow a device to be replaced without removing it from the array first. With hot-replace a spare can be activated and recovery can start while the original device is still in place, thus allowing a transition from an unreliable device to a reliable device without leaving the array degraded during the transition. It can also be use when the original device is still reliable but it not wanted for some reason. This will eventually be supported in RAID4/5/6 and RAID10. This patch adds a super-block flag to distinguish the replacement device. If an old kernel sees this flag it will reject the device. It also adds two per-device flags which are viewable and settable via sysfs. "want_replacement" can be set to request that a device be replaced. "replacement" is set to show that this device is replacing another device. The "rd%d" links in /sys/block/mdXx/md only apply to the original device, not the replacement. We currently don't make links for the replacement - there doesn't seem to be a need. Signed-off-by: NeilBrown <neilb@suse.de>
Diffstat (limited to 'include/linux/raid')
-rw-r--r--include/linux/raid/md_p.h7
1 files changed, 5 insertions, 2 deletions
diff --git a/include/linux/raid/md_p.h b/include/linux/raid/md_p.h
index 9e65d9e2066..6f6df86f1ae 100644
--- a/include/linux/raid/md_p.h
+++ b/include/linux/raid/md_p.h
@@ -277,7 +277,10 @@ struct mdp_superblock_1 {
*/
#define MD_FEATURE_RESHAPE_ACTIVE 4
#define MD_FEATURE_BAD_BLOCKS 8 /* badblock list is not empty */
-
-#define MD_FEATURE_ALL (1|2|4|8)
+#define MD_FEATURE_REPLACEMENT 16 /* This device is replacing an
+ * active device with same 'role'.
+ * 'recovery_offset' is also set.
+ */
+#define MD_FEATURE_ALL (1|2|4|8|16)
#endif