[PATCH 8 of 8] MD: raid5 do not set fullsync

Add new flag for struct mdk_rdev_s to indicate when recovery can use bitmap

Device-mapper can tell if a device is in-sync, in need of partial (bitmap aided)
recovery, or in need of complete recovery. The raid5 code assumes that if a
device is not in-sync, then it must undergo complete recovery - it does not
honor the bitmap. The flag 'RecoverByBitmap' has been introduced to force raid5
not to set 'conf->fullsync' if the superblock routines have already determined
that only a partial recovery is necessary.

RFC-by: Jonathan Brassow

Index: linux-2.6/drivers/md/raid5.c
============================================================ =======
--- linux-2.6.orig/drivers/md/raid5.c
+++ linux-2.6/drivers/md/raid5.c
@@ -4858,7 +4858,7 @@ static raid5_conf_t *setup_conf(mddev_t
printk(KERN_INFO "md/raid:%s: device %s operational as raid"
" disk %d\n",
mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
- } else
+ } else if (!test_bit(RecoverByBitmap, &rdev->flags))
/* Cannot rely on bitmap to complete recovery */
conf->fullsync = 1;
}
Index: linux-2.6/drivers/md/md.h
============================================================ =======
--- linux-2.6.orig/drivers/md/md.h
+++ linux-2.6/drivers/md/md.h
@@ -77,6 +77,8 @@ struct mdk_rdev_s
#define Blocked 8 /* An error occurred on an externally
* managed array, don't allow writes
* until it is cleared */
+#define RecoverByBitmap 9 /* Used by device-mapper to ensure this
+ * device is recovered by the bitmap. */
wait_queue_head_t blocked_wait;

int desc_nr; /* descriptor index in the superblock */


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Re: [PATCH 8 of 8] MD: raid5 do not set fullsync

On Tue, 07 Jun 2011 17:52:43 -0500 Jonathan Brassow
wrote:

> Add new flag for struct mdk_rdev_s to indicate when recovery can use bitmap
>
> Device-mapper can tell if a device is in-sync, in need of partial (bitmap aided)
> recovery, or in need of complete recovery. The raid5 code assumes that if a
> device is not in-sync, then it must undergo complete recovery - it does not
> honor the bitmap. The flag 'RecoverByBitmap' has been introduced to force raid5
> not to set 'conf->fullsync' if the superblock routines have already determined
> that only a partial recovery is necessary.
>
> RFC-by: Jonathan Brassow
>
> Index: linux-2.6/drivers/md/raid5.c
> ============================================================ =======
> --- linux-2.6.orig/drivers/md/raid5.c
> +++ linux-2.6/drivers/md/raid5.c
> @@ -4858,7 +4858,7 @@ static raid5_conf_t *setup_conf(mddev_t
> printk(KERN_INFO "md/raid:%s: device %s operational as raid"
> " disk %d\n",
> mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
> - } else
> + } else if (!test_bit(RecoverByBitmap, &rdev->flags))
> /* Cannot rely on bitmap to complete recovery */
> conf->fullsync = 1;

I think we can just do
} else if (rdev->saved_raid_disk != raid_disk)

and not add an extra flag.
This is more in keeping with e.g. raid5_add_disk.

Thanks,

NeilBrown


> }
> Index: linux-2.6/drivers/md/md.h
> ============================================================ =======
> --- linux-2.6.orig/drivers/md/md.h
> +++ linux-2.6/drivers/md/md.h
> @@ -77,6 +77,8 @@ struct mdk_rdev_s
> #define Blocked 8 /* An error occurred on an externally
> * managed array, don't allow writes
> * until it is cleared */
> +#define RecoverByBitmap 9 /* Used by device-mapper to ensure this
> + * device is recovered by the bitmap. */
> wait_queue_head_t blocked_wait;
>
> int desc_nr; /* descriptor index in the superblock */
>
>
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