Patch name: dm-raid-allow-metadata-devices.patch
Add the ability to parse and use metadata devices. Metadata
devices are not required. If they are provided, they are used
to store a (minimal) superblock and bitmap.
RFC-by: Jonathan Brassow <jbrassow@xxxxxxxxxx>
Index: linux-2.6/drivers/md/dm-raid.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-raid.c
+++ linux-2.6/drivers/md/dm-raid.c
@@ -7,6 +7,7 @@
#include "md.h"
#include "raid5.h"
#include "dm.h"
+#include "bitmap.h"
#define DM_MSG_PREFIX "raid"
@@ -32,6 +33,13 @@ struct raid_set {
struct dm_target *ti;
struct mddev_s md;
struct raid_type *raid_type;
+
+ enum sync {
+ DEFAULTSYNC, /* Synchronize if necessary */
+ NOSYNC, /* Devices known to be already in sync */
+ FORCESYNC, /* Force a sync to happen */
+ } sync;
+
struct target_callbacks callbacks;
struct raid_dev dev[0];
};
@@ -115,6 +123,12 @@ static void context_free(struct raid_set
{
int i;
for (i = 0; i < rs->md.raid_disks; i++) {
+ if (rs->dev[i].meta_dev)
+ dm_put_device(rs->ti, rs->dev[i].meta_dev);
+ if (rs->dev[i].rdev.sb_page)
+ put_page(rs->dev[i].rdev.sb_page);
+ rs->dev[i].rdev.sb_page = NULL;
+ rs->dev[i].rdev.sb_loaded = 0;
if (rs->dev[i].data_dev)
dm_put_device(rs->ti, rs->dev[i].data_dev);
}
@@ -125,11 +139,20 @@ static void context_free(struct raid_set
* <meta_dev>: meta device name or '-' if missing
* <data_dev>: data device name or '-' if missing
*
- * This code parses those words.
+ * The following are acceptable:
+ * - -
+ * - <data_dev>
+ * <meta_dev> <data_dev>
+ * The following is not allowed:
+ * <meta_dev> -
+ *
+ * This code parses those words. If there is a failure,
+ * context_free must be used to unwind the operations.
*/
static int dev_parms(struct raid_set *rs, char **argv)
{
int i;
+ int metadata_available = 0;
for (i = 0; i < rs->md.raid_disks; i++, argv += 2) {
int err = 0;
@@ -147,8 +170,16 @@ static int dev_parms(struct raid_set *rs
rs->dev[i].rdev.mddev = &rs->md;
if (strcmp(argv[0], "-") != 0) {
- rs->ti->error = "Metadata devices not supported";
- return -EINVAL;
+ err = dm_get_device(rs->ti, argv[0],
+ dm_table_get_mode(rs->ti->table),
+ &rs->dev[i].meta_dev);
+ rs->ti->error = "RAID metadata device lookup failure";
+ if (err)
+ return err;
+
+ rs->dev[i].rdev.sb_page = alloc_page(GFP_KERNEL);
+ if (!rs->dev[i].rdev.sb_page)
+ return -ENOMEM;
}
if (strcmp(argv[1], "-") == 0) {
@@ -157,6 +188,10 @@ static int dev_parms(struct raid_set *rs
(rs->dev[i].rdev.recovery_offset == 0))
return -EINVAL;
+ rs->ti->error = "No data device supplied with metadata device";
+ if (rs->dev[i].meta_dev)
+ return -EINVAL;
+
continue;
}
@@ -167,10 +202,44 @@ static int dev_parms(struct raid_set *rs
if (err)
return err;
+ if (rs->dev[i].meta_dev) {
+ metadata_available = 1;
+ rs->dev[i].rdev.meta_bdev = rs->dev[i].meta_dev->bdev;
+ }
rs->dev[i].rdev.bdev = rs->dev[i].data_dev->bdev;
list_add(&rs->dev[i].rdev.same_set, &rs->md.disks);
}
+ if (metadata_available) {
+ rs->md.external = 0;
+ rs->md.persistent = 1;
+ rs->md.major_version = 2;
+ }
+ /*
+ * Now we know if there were any metadata devices specified.
+ * DEFAULTSYNC is to perform the sync if there are no metadata
+ * devices, but to defer judgement (not perform the sync) if
+ * there are metadata devices.
+ *
+ * FIXME: make sure we don't need to make further adjustments if
+ * there are devices to rebuild (that should be handled
+ * independently by rdev's recovery_offset)
+ */
+ switch (rs->sync) {
+ case NOSYNC:
+ rs->md.recovery_cp = MaxSector;
+ break;
+ case FORCESYNC:
+ rs->md.recovery_cp = 0;
+ break;
+ case DEFAULTSYNC:
+ rs->md.recovery_cp = (metadata_available) ? MaxSector : 0;
+ break;
+ default:
+ BUG();
+ }
+
+
rs->ti->error = NULL;
return 0;
}
@@ -228,17 +297,27 @@ static int parse_raid_params(struct raid
return -EINVAL;
rs->ti->error = "Bad RAID option";
+ /*
+ * Default behavior is to treat as in-sync
+ * FIXME: Might be better to default to MaxSector
+ * if there are metadata disks, but 0 otherwise
+ */
+ rs->sync = DEFAULTSYNC;
if (num_raid_params) {
if (!strcmp(argv[0], "nosync"))
- rs->md.recovery_cp = MaxSector;
+ rs->sync = NOSYNC;
else if (!strcmp(argv[0], "sync"))
- rs->md.recovery_cp = 0;
- else
+ rs->sync = FORCESYNC;
+ else /* No other valid options yet */
return -EINVAL;
}
- rs->md.persistent = 0;
+ /*
+ * These will be adjusted in dev_parms if
+ * metadata devices are provided.
+ */
rs->md.external = 1;
+ rs->md.persistent = 0;
rs->ti->error = NULL;
return 0;
@@ -272,8 +351,6 @@ static void raid_unplug(void *v)
* <raid_type> <#raid_params> <raid_params> \
* <#raid_devs> { <meta_dev1> <dev1> .. <meta_devN> <devN> }
*
- * ** metadata devices are not supported yet, use '-' instead **
- *
* <raid_params> varies by <raid_type>. See 'parse_raid_params' for
* details on possible <raid_params>.
*/
@@ -442,7 +519,10 @@ static int raid_status(struct dm_target
DMEMIT("%d ", rs->md.raid_disks);
for (i = 0; i < rs->md.raid_disks; i++) {
- DMEMIT("- "); /* metadata device */
+ if (rs->dev[i].meta_dev)
+ DMEMIT("%s ", rs->dev[i].meta_dev->name);
+ else
+ DMEMIT("- ");
if (rs->dev[i].data_dev)
DMEMIT("%s ", rs->dev[i].data_dev->name);
@@ -501,6 +581,7 @@ static void raid_resume(struct dm_target
{
struct raid_set *rs = ti->private;
+ bitmap_load(&rs->md);
mddev_resume(&rs->md);
}
--
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