[PATCH 1/3] md:Add support for Raid0->Raid5 takeover

[PATCH 1/3] md:Add support for Raid0->Raid5 takeover

[Trela, Maciej]

Hello Neil, I'm sending patches with new takeover transitions proposal:
0->5(4), 5(4)->0, 10->0, 0->10.

Regards,
Maciek


Signed-off-by: Maciej Trela <maciej.trela@intel.com>
---
 drivers/md/raid5.c |   50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 50 insertions(+), 0 deletions(-)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index e84204e..0fe78ea 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -5614,6 +5614,39 @@ static void raid5_quiesce(mddev_t *mddev, int state)
 }
 
 
+static void *raid5_takeover_raid0(mddev_t *mddev)
+{
+	int chunksect;
+	
+	if (mddev->degraded > 0) {
+	    printk(KERN_ERR "ERROR: Raid0 with degraded disks!: %d\n", mddev->degraded);
+		return ERR_PTR(-EINVAL);
+	}
+	
+	chunksect = 64*2; /* 64K by default */
+
+	/* The array must be an exact multiple of chunksize */
+	while (chunksect && (mddev->array_sectors & (chunksect-1)))
+		chunksect >>= 1;
+
+	if ((chunksect<<9) < STRIPE_SIZE) {
+		/* array size does not allow a suitable chunk size */
+		return ERR_PTR(-EINVAL);
+	}
+	
+	mddev->new_level = 5;
+	mddev->new_layout = ALGORITHM_PARITY_N;
+	mddev->new_chunk_sectors = chunksect;
+	mddev->degraded++;
+	mddev->raid_disks++;
+	mddev->delta_disks++;
+	/* make sure it will be not marked as dirty */
+	mddev->recovery_cp = MaxSector;
+
+	return setup_conf(mddev);
+}
+
+
 static void *raid5_takeover_raid1(mddev_t *mddev)
 {
 	int chunksect;
@@ -5737,12 +5770,29 @@ static int raid6_check_reshape(mddev_t *mddev)
 
 static void *raid5_takeover(mddev_t *mddev)
 {
+	mdk_rdev_t *rdev;
+	sector_t sectors, dev_sectors;
+
 	/* raid5 can take over:
 	 *  raid0 - if all devices are the same - make it a raid4 layout
 	 *  raid1 - if there are two drives.  We need to know the chunk size
 	 *  raid4 - trivial - just use a raid4 layout.
 	 *  raid6 - Providing it is a *_6 layout
 	 */
+	if (mddev->level == 0) {
+		/* make sure all devices are the same (only one zone is supported) */
+		sectors = mddev->dev_sectors;
+		sector_div(sectors, mddev->chunk_sectors);
+		list_for_each_entry(rdev, &mddev->disks, same_set) {
+			dev_sectors = rdev->sectors;
+			sector_div(dev_sectors, mddev->chunk_sectors);
+			if (dev_sectors != sectors) {
+				printk("error: cannot takeover raid 0 with different dev sizes.\n");
+				return ERR_PTR(-EINVAL);
+			}
+		}
+		return raid5_takeover_raid0(mddev);
+	}
 
 	if (mddev->level == 1)
 		return raid5_takeover_raid1(mddev);
-- 
1.6.3.3

Re: [PATCH 1/3] md:Add support for Raid0->Raid5 takeover

[Neil Brown]

On Fri, 29 Jan 2010 14:54:03 +0000
"Trela, Maciej" <Maciej.Trela@intel.com> wrote:

> Hello Neil, I'm sending patches with new takeover transitions proposal:
> 0->5(4), 5(4)->0, 10->0, 0->10.
> 
> Regards,
> Maciek
> 
> 
> Signed-off-by: Maciej Trela <maciej.trela@intel.com>
> ---
>  drivers/md/raid5.c |   50 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 50 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index e84204e..0fe78ea 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -5614,6 +5614,39 @@ static void raid5_quiesce(mddev_t *mddev, int state)
>  }
>  
>  
> +static void *raid5_takeover_raid0(mddev_t *mddev)
> +{
> +	int chunksect;
> +	
> +	if (mddev->degraded > 0) {
> +	    printk(KERN_ERR "ERROR: Raid0 with degraded disks!: %d\n", mddev->degraded);
> +		return ERR_PTR(-EINVAL);
> +	}
> +	
> +	chunksect = 64*2; /* 64K by default */
> +
> +	/* The array must be an exact multiple of chunksize */
> +	while (chunksect && (mddev->array_sectors & (chunksect-1)))
> +		chunksect >>= 1;
> +
> +	if ((chunksect<<9) < STRIPE_SIZE) {
> +		/* array size does not allow a suitable chunk size */
> +		return ERR_PTR(-EINVAL);
> +	}

This is wrong.  The chunksize for RAID5 must be exactly the same as the
chunksize for RAID0.  There is no place for guessing.



> +	
> +	mddev->new_level = 5;
> +	mddev->new_layout = ALGORITHM_PARITY_N;
> +	mddev->new_chunk_sectors = chunksect;
> +	mddev->degraded++;
> +	mddev->raid_disks++;
> +	mddev->delta_disks++;
> +	/* make sure it will be not marked as dirty */
> +	mddev->recovery_cp = MaxSector;
> +
> +	return setup_conf(mddev);
> +}
> +
> +
>  static void *raid5_takeover_raid1(mddev_t *mddev)
>  {
>  	int chunksect;
> @@ -5737,12 +5770,29 @@ static int raid6_check_reshape(mddev_t *mddev)
>  
>  static void *raid5_takeover(mddev_t *mddev)
>  {
> +	mdk_rdev_t *rdev;
> +	sector_t sectors, dev_sectors;
> +
>  	/* raid5 can take over:
>  	 *  raid0 - if all devices are the same - make it a raid4 layout
>  	 *  raid1 - if there are two drives.  We need to know the chunk size
>  	 *  raid4 - trivial - just use a raid4 layout.
>  	 *  raid6 - Providing it is a *_6 layout
>  	 */
> +	if (mddev->level == 0) {
> +		/* make sure all devices are the same (only one zone is supported) */
> +		sectors = mddev->dev_sectors;
> +		sector_div(sectors, mddev->chunk_sectors);
> +		list_for_each_entry(rdev, &mddev->disks, same_set) {
> +			dev_sectors = rdev->sectors;
> +			sector_div(dev_sectors, mddev->chunk_sectors);
> +			if (dev_sectors != sectors) {
> +				printk("error: cannot takeover raid 0 with different dev sizes.\n");
> +				return ERR_PTR(-EINVAL);
> +			}
> +		}
> +		return raid5_takeover_raid0(mddev);
> +	}

I would rather you just look inside the raid0_private_data to see tha
nr_strip_zones is zero.


Thanks,
NeilBrown

RE: [PATCH 1/3] md:Add support for Raid0->Raid5 takeover

[Trela, Maciej]

> 
> This is wrong.  The chunksize for RAID5 must be exactly the same as the
> chunksize for RAID0.  There is no place for guessing.
> 
> 
> 
> I would rather you just look inside the raid0_private_data to see tha
> nr_strip_zones is zero.
>

Both are fixed now.

Maciek Trela.
 


Signed-off-by: Maciej Trela <maciej.trela@intel.com>
---
 drivers/md/raid5.c |   33 +++++++++++++++++++++++++++++++++
 1 files changed, 33 insertions(+), 0 deletions(-)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index e84204e..2b99ad8 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -52,6 +52,7 @@
 #include <linux/cpu.h>
 #include "md.h"
 #include "raid5.h"
+#include "raid0.h"
 #include "bitmap.h"
 
 /*
@@ -5614,6 +5615,27 @@ static void raid5_quiesce(mddev_t *mddev, int state)
 }
 
 
+static void *raid5_takeover_raid0(mddev_t *mddev)
+{
+
+	if (mddev->degraded > 0) {
+	    printk(KERN_ERR "ERROR: Raid0 with degraded disks!: %d\n", mddev->degraded);
+		return ERR_PTR(-EINVAL);
+	}
+	
+	mddev->new_level = 5;
+	mddev->new_layout = ALGORITHM_PARITY_N;
+	mddev->new_chunk_sectors = mddev->chunk_sectors;
+	mddev->degraded++;
+	mddev->raid_disks++;
+	mddev->delta_disks++;
+	/* make sure it will be not marked as dirty */
+	mddev->recovery_cp = MaxSector;
+
+	return setup_conf(mddev);
+}
+
+
 static void *raid5_takeover_raid1(mddev_t *mddev)
 {
 	int chunksect;
@@ -5737,12 +5759,23 @@ static int raid6_check_reshape(mddev_t *mddev)
 
 static void *raid5_takeover(mddev_t *mddev)
 {
+	struct raid0_private_data *raid0_priv;
+
 	/* raid5 can take over:
 	 *  raid0 - if all devices are the same - make it a raid4 layout
 	 *  raid1 - if there are two drives.  We need to know the chunk size
 	 *  raid4 - trivial - just use a raid4 layout.
 	 *  raid6 - Providing it is a *_6 layout
 	 */
+	if (mddev->level == 0) {
+		/* for raid0 takeover only one zone is supported */
+		raid0_priv = (struct raid0_private_data*)(mddev->private);
+		if (raid0_priv->nr_strip_zones > 1) {
+				printk("error: cannot takeover raid 0 with more than one zone.\n");
+				return ERR_PTR(-EINVAL);
+		}
+		return raid5_takeover_raid0(mddev);
+	}
 
 	if (mddev->level == 1)
 		return raid5_takeover_raid1(mddev);
-- 
1.6.3.3