[PATCH] md: support write-mostly device in raid1
This allows a device in a raid1 to be marked as "write mostly". Read requests
will only be sent if there is no other option.
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/md/md.c b/drivers/md/md.c
index ae65446..f1ac356 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -670,6 +670,7 @@
if (mddev->level != LEVEL_MULTIPATH) {
rdev->faulty = 0;
+ rdev->flags = 0;
desc = sb->disks + rdev->desc_nr;
if (desc->state & (1<<MD_DISK_FAULTY))
@@ -679,6 +680,8 @@
rdev->in_sync = 1;
rdev->raid_disk = desc->raid_disk;
}
+ if (desc->state & (1<<MD_DISK_WRITEMOSTLY))
+ set_bit(WriteMostly, &rdev->flags);
} else /* MULTIPATH are always insync */
rdev->in_sync = 1;
return 0;
@@ -777,6 +780,8 @@
spare++;
working++;
}
+ if (test_bit(WriteMostly, &rdev2->flags))
+ d->state |= (1<<MD_DISK_WRITEMOSTLY);
}
/* now set the "removed" and "faulty" bits on any missing devices */
@@ -990,6 +995,9 @@
rdev->raid_disk = role;
break;
}
+ rdev->flags = 0;
+ if (sb->devflags & WriteMostly1)
+ set_bit(WriteMostly, &rdev->flags);
} else /* MULTIPATH are always insync */
rdev->in_sync = 1;
@@ -2152,6 +2160,8 @@
info.state |= (1<<MD_DISK_ACTIVE);
info.state |= (1<<MD_DISK_SYNC);
}
+ if (test_bit(WriteMostly, &rdev->flags))
+ info.state |= (1<<MD_DISK_WRITEMOSTLY);
} else {
info.major = info.minor = 0;
info.raid_disk = -1;
@@ -2237,6 +2247,9 @@
rdev->saved_raid_disk = rdev->raid_disk;
rdev->in_sync = 0; /* just to be sure */
+ if (info->state & (1<<MD_DISK_WRITEMOSTLY))
+ set_bit(WriteMostly, &rdev->flags);
+
rdev->raid_disk = -1;
err = bind_rdev_to_array(rdev, mddev);
if (err)
@@ -2277,6 +2290,9 @@
else
rdev->in_sync = 0;
+ if (info->state & (1<<MD_DISK_WRITEMOSTLY))
+ set_bit(WriteMostly, &rdev->flags);
+
err = bind_rdev_to_array(rdev, mddev);
if (err) {
export_rdev(rdev);
@@ -3329,6 +3345,8 @@
char b[BDEVNAME_SIZE];
seq_printf(seq, " %s[%d]",
bdevname(rdev->bdev,b), rdev->desc_nr);
+ if (test_bit(WriteMostly, &rdev->flags))
+ seq_printf(seq, "(W)");
if (rdev->faulty) {
seq_printf(seq, "(F)");
continue;