[PATCH 8/9] btrfs: Make more generic the code for RAID 6 rebuilding

[Goffredo Baroncelli]

From: Goffredo Baroncelli 

The original code which handles the recovery of a RAID 6 disks array
assumes that all reads are multiple of 1 << GRUB_DISK_SECTOR_BITS and it
assumes that all the I/O is done via the struct grub_diskfilter_segment.
This is not true for the btrfs code. In order to reuse the native
grub_raid6_recover() code, it is modified to not call
grub_diskfilter_read_node() directly, but to call an handler passed
as an argument.

Signed-off-by: Goffredo Baroncelli 
Reviewed-by: Daniel Kiper 
---
 grub-core/disk/raid6_recover.c | 52 ++
 include/grub/diskfilter.h  |  9 ++
 2 files changed, 43 insertions(+), 18 deletions(-)

diff --git a/grub-core/disk/raid6_recover.c b/grub-core/disk/raid6_recover.c
index aa674f6ca..0cf691ddf 100644
--- a/grub-core/disk/raid6_recover.c
+++ b/grub-core/disk/raid6_recover.c
@@ -74,14 +74,26 @@ mod_255 (unsigned x)
 }
 
 static grub_err_t
-grub_raid6_recover (struct grub_diskfilter_segment *array, int disknr, int p,
-char *buf, grub_disk_addr_t sector, grub_size_t size)
+raid6_recover_read_node (void *data, int disknr,
+   grub_uint64_t sector,
+   void *buf, grub_size_t size)
+{
+struct grub_diskfilter_segment *array = data;
+
+return grub_diskfilter_read_node (>nodes[disknr],
+ (grub_disk_addr_t)sector,
+ size >> GRUB_DISK_SECTOR_BITS, buf);
+}
+
+grub_err_t
+grub_raid6_recover_gen (void *data, grub_uint64_t nstripes, int disknr, int p,
+   char *buf, grub_uint64_t sector, grub_size_t size,
+   int layout, raid_recover_read_t read_func)
 {
   int i, q, pos;
   int bad1 = -1, bad2 = -1;
   char *pbuf = 0, *qbuf = 0;
 
-  size <<= GRUB_DISK_SECTOR_BITS;
   pbuf = grub_zalloc (size);
   if (!pbuf)
 goto quit;
@@ -91,17 +103,17 @@ grub_raid6_recover (struct grub_diskfilter_segment *array, 
int disknr, int p,
 goto quit;
 
   q = p + 1;
-  if (q == (int) array->node_count)
+  if (q == (int) nstripes)
 q = 0;
 
   pos = q + 1;
-  if (pos == (int) array->node_count)
+  if (pos == (int) nstripes)
 pos = 0;
 
-  for (i = 0; i < (int) array->node_count - 2; i++)
+  for (i = 0; i < (int) nstripes - 2; i++)
 {
   int c;
-  if (array->layout & GRUB_RAID_LAYOUT_MUL_FROM_POS)
+  if (layout & GRUB_RAID_LAYOUT_MUL_FROM_POS)
c = pos;
   else
c = i;
@@ -109,8 +121,7 @@ grub_raid6_recover (struct grub_diskfilter_segment *array, 
int disknr, int p,
 bad1 = c;
   else
 {
-  if (! grub_diskfilter_read_node (>nodes[pos], sector,
-  size >> GRUB_DISK_SECTOR_BITS, buf))
+ if (!read_func(data, pos, sector, buf, size))
 {
   grub_crypto_xor (pbuf, pbuf, buf, size);
   grub_raid_block_mulx (c, buf, size);
@@ -128,7 +139,7 @@ grub_raid6_recover (struct grub_diskfilter_segment *array, 
int disknr, int p,
 }
 
   pos++;
-  if (pos == (int) array->node_count)
+  if (pos == (int) nstripes)
 pos = 0;
 }
 
@@ -139,16 +150,14 @@ grub_raid6_recover (struct grub_diskfilter_segment 
*array, int disknr, int p,
   if (bad2 < 0)
 {
   /* One bad device */
-  if ((! grub_diskfilter_read_node (>nodes[p], sector,
-   size >> GRUB_DISK_SECTOR_BITS, buf)))
+  if (!read_func(data, p, sector, buf, size))
 {
   grub_crypto_xor (buf, buf, pbuf, size);
   goto quit;
 }
 
   grub_errno = GRUB_ERR_NONE;
-  if (grub_diskfilter_read_node (>nodes[q], sector,
-size >> GRUB_DISK_SECTOR_BITS, buf))
+  if (read_func(data, q, sector, buf, size))
 goto quit;
 
   grub_crypto_xor (buf, buf, qbuf, size);
@@ -160,14 +169,12 @@ grub_raid6_recover (struct grub_diskfilter_segment 
*array, int disknr, int p,
   /* Two bad devices */
   unsigned c;
 
-  if (grub_diskfilter_read_node (>nodes[p], sector,
-size >> GRUB_DISK_SECTOR_BITS, buf))
+  if (read_func(data, p, sector, buf, size))
 goto quit;
 
   grub_crypto_xor (pbuf, pbuf, buf, size);
 
-  if (grub_diskfilter_read_node (>nodes[q], sector,
-size >> GRUB_DISK_SECTOR_BITS, buf))
+  if (read_func(data, q, sector, buf, size))
 goto quit;
 
   grub_crypto_xor (qbuf, qbuf, buf, size);
@@ -190,6 +197,15 @@ quit:
   return grub_errno;
 }
 
+static grub_err_t
+grub_raid6_recover (struct grub_diskfilter_segment *array, int disknr, int p,
+char *buf, grub_disk_addr_t sector, grub_size_t size)
+{
+  return grub_raid6_recover_gen (array, array->node_count, disknr, p, buf,
+sector, size << GRUB_DISK_SECTOR_BITS,
+

[PATCH 8/9] btrfs: Make more generic the code for RAID 6 rebuilding

[Goffredo Baroncelli]

From: Goffredo Baroncelli 

The original code which handles the recovery of a RAID 6 disks array
assumes that all reads are multiple of 1 << GRUB_DISK_SECTOR_BITS and it
assumes that all the I/O is done via the struct grub_diskfilter_segment.
This is not true for the btrfs code. In order to reuse the native
grub_raid6_recover() code, it is modified to not call
grub_diskfilter_read_node() directly, but to call an handler passed
as an argument.

Signed-off-by: Goffredo Baroncelli 
Reviewed-by: Daniel Kiper 
---
 grub-core/disk/raid6_recover.c | 52 ++
 include/grub/diskfilter.h  |  9 ++
 2 files changed, 43 insertions(+), 18 deletions(-)

diff --git a/grub-core/disk/raid6_recover.c b/grub-core/disk/raid6_recover.c
index aa674f6ca..0cf691ddf 100644
--- a/grub-core/disk/raid6_recover.c
+++ b/grub-core/disk/raid6_recover.c
@@ -74,14 +74,26 @@ mod_255 (unsigned x)
 }
 
 static grub_err_t
-grub_raid6_recover (struct grub_diskfilter_segment *array, int disknr, int p,
-char *buf, grub_disk_addr_t sector, grub_size_t size)
+raid6_recover_read_node (void *data, int disknr,
+   grub_uint64_t sector,
+   void *buf, grub_size_t size)
+{
+struct grub_diskfilter_segment *array = data;
+
+return grub_diskfilter_read_node (>nodes[disknr],
+ (grub_disk_addr_t)sector,
+ size >> GRUB_DISK_SECTOR_BITS, buf);
+}
+
+grub_err_t
+grub_raid6_recover_gen (void *data, grub_uint64_t nstripes, int disknr, int p,
+   char *buf, grub_uint64_t sector, grub_size_t size,
+   int layout, raid_recover_read_t read_func)
 {
   int i, q, pos;
   int bad1 = -1, bad2 = -1;
   char *pbuf = 0, *qbuf = 0;
 
-  size <<= GRUB_DISK_SECTOR_BITS;
   pbuf = grub_zalloc (size);
   if (!pbuf)
 goto quit;
@@ -91,17 +103,17 @@ grub_raid6_recover (struct grub_diskfilter_segment *array, 
int disknr, int p,
 goto quit;
 
   q = p + 1;
-  if (q == (int) array->node_count)
+  if (q == (int) nstripes)
 q = 0;
 
   pos = q + 1;
-  if (pos == (int) array->node_count)
+  if (pos == (int) nstripes)
 pos = 0;
 
-  for (i = 0; i < (int) array->node_count - 2; i++)
+  for (i = 0; i < (int) nstripes - 2; i++)
 {
   int c;
-  if (array->layout & GRUB_RAID_LAYOUT_MUL_FROM_POS)
+  if (layout & GRUB_RAID_LAYOUT_MUL_FROM_POS)
c = pos;
   else
c = i;
@@ -109,8 +121,7 @@ grub_raid6_recover (struct grub_diskfilter_segment *array, 
int disknr, int p,
 bad1 = c;
   else
 {
-  if (! grub_diskfilter_read_node (>nodes[pos], sector,
-  size >> GRUB_DISK_SECTOR_BITS, buf))
+ if (!read_func(data, pos, sector, buf, size))
 {
   grub_crypto_xor (pbuf, pbuf, buf, size);
   grub_raid_block_mulx (c, buf, size);
@@ -128,7 +139,7 @@ grub_raid6_recover (struct grub_diskfilter_segment *array, 
int disknr, int p,
 }
 
   pos++;
-  if (pos == (int) array->node_count)
+  if (pos == (int) nstripes)
 pos = 0;
 }
 
@@ -139,16 +150,14 @@ grub_raid6_recover (struct grub_diskfilter_segment 
*array, int disknr, int p,
   if (bad2 < 0)
 {
   /* One bad device */
-  if ((! grub_diskfilter_read_node (>nodes[p], sector,
-   size >> GRUB_DISK_SECTOR_BITS, buf)))
+  if (!read_func(data, p, sector, buf, size))
 {
   grub_crypto_xor (buf, buf, pbuf, size);
   goto quit;
 }
 
   grub_errno = GRUB_ERR_NONE;
-  if (grub_diskfilter_read_node (>nodes[q], sector,
-size >> GRUB_DISK_SECTOR_BITS, buf))
+  if (read_func(data, q, sector, buf, size))
 goto quit;
 
   grub_crypto_xor (buf, buf, qbuf, size);
@@ -160,14 +169,12 @@ grub_raid6_recover (struct grub_diskfilter_segment 
*array, int disknr, int p,
   /* Two bad devices */
   unsigned c;
 
-  if (grub_diskfilter_read_node (>nodes[p], sector,
-size >> GRUB_DISK_SECTOR_BITS, buf))
+  if (read_func(data, p, sector, buf, size))
 goto quit;
 
   grub_crypto_xor (pbuf, pbuf, buf, size);
 
-  if (grub_diskfilter_read_node (>nodes[q], sector,
-size >> GRUB_DISK_SECTOR_BITS, buf))
+  if (read_func(data, q, sector, buf, size))
 goto quit;
 
   grub_crypto_xor (qbuf, qbuf, buf, size);
@@ -190,6 +197,15 @@ quit:
   return grub_errno;
 }
 
+static grub_err_t
+grub_raid6_recover (struct grub_diskfilter_segment *array, int disknr, int p,
+char *buf, grub_disk_addr_t sector, grub_size_t size)
+{
+  return grub_raid6_recover_gen (array, array->node_count, disknr, p, buf,
+sector, size << GRUB_DISK_SECTOR_BITS,
+

[PATCH 8/9] btrfs: Make more generic the code for RAID 6 rebuilding

[Goffredo Baroncelli]

From: Goffredo Baroncelli 

The original code which handles the recovery of a RAID 6 disks array
assumes that all reads are multiple of 1 << GRUB_DISK_SECTOR_BITS and it
assumes that all the I/O is done via the struct grub_diskfilter_segment.
This is not true for the btrfs code. In order to reuse the native
grub_raid6_recover() code, it is modified to not call
grub_diskfilter_read_node() directly, but to call an handler passed
as an argument.

Signed-off-by: Goffredo Baroncelli 
Reviewed-by: Daniel Kiper 
---
 grub-core/disk/raid6_recover.c | 52 ++
 include/grub/diskfilter.h  |  9 ++
 2 files changed, 43 insertions(+), 18 deletions(-)

diff --git a/grub-core/disk/raid6_recover.c b/grub-core/disk/raid6_recover.c
index aa674f6ca..0cf691ddf 100644
--- a/grub-core/disk/raid6_recover.c
+++ b/grub-core/disk/raid6_recover.c
@@ -74,14 +74,26 @@ mod_255 (unsigned x)
 }
 
 static grub_err_t
-grub_raid6_recover (struct grub_diskfilter_segment *array, int disknr, int p,
-char *buf, grub_disk_addr_t sector, grub_size_t size)
+raid6_recover_read_node (void *data, int disknr,
+   grub_uint64_t sector,
+   void *buf, grub_size_t size)
+{
+struct grub_diskfilter_segment *array = data;
+
+return grub_diskfilter_read_node (>nodes[disknr],
+ (grub_disk_addr_t)sector,
+ size >> GRUB_DISK_SECTOR_BITS, buf);
+}
+
+grub_err_t
+grub_raid6_recover_gen (void *data, grub_uint64_t nstripes, int disknr, int p,
+   char *buf, grub_uint64_t sector, grub_size_t size,
+   int layout, raid_recover_read_t read_func)
 {
   int i, q, pos;
   int bad1 = -1, bad2 = -1;
   char *pbuf = 0, *qbuf = 0;
 
-  size <<= GRUB_DISK_SECTOR_BITS;
   pbuf = grub_zalloc (size);
   if (!pbuf)
 goto quit;
@@ -91,17 +103,17 @@ grub_raid6_recover (struct grub_diskfilter_segment *array, 
int disknr, int p,
 goto quit;
 
   q = p + 1;
-  if (q == (int) array->node_count)
+  if (q == (int) nstripes)
 q = 0;
 
   pos = q + 1;
-  if (pos == (int) array->node_count)
+  if (pos == (int) nstripes)
 pos = 0;
 
-  for (i = 0; i < (int) array->node_count - 2; i++)
+  for (i = 0; i < (int) nstripes - 2; i++)
 {
   int c;
-  if (array->layout & GRUB_RAID_LAYOUT_MUL_FROM_POS)
+  if (layout & GRUB_RAID_LAYOUT_MUL_FROM_POS)
c = pos;
   else
c = i;
@@ -109,8 +121,7 @@ grub_raid6_recover (struct grub_diskfilter_segment *array, 
int disknr, int p,
 bad1 = c;
   else
 {
-  if (! grub_diskfilter_read_node (>nodes[pos], sector,
-  size >> GRUB_DISK_SECTOR_BITS, buf))
+ if (!read_func(data, pos, sector, buf, size))
 {
   grub_crypto_xor (pbuf, pbuf, buf, size);
   grub_raid_block_mulx (c, buf, size);
@@ -128,7 +139,7 @@ grub_raid6_recover (struct grub_diskfilter_segment *array, 
int disknr, int p,
 }
 
   pos++;
-  if (pos == (int) array->node_count)
+  if (pos == (int) nstripes)
 pos = 0;
 }
 
@@ -139,16 +150,14 @@ grub_raid6_recover (struct grub_diskfilter_segment 
*array, int disknr, int p,
   if (bad2 < 0)
 {
   /* One bad device */
-  if ((! grub_diskfilter_read_node (>nodes[p], sector,
-   size >> GRUB_DISK_SECTOR_BITS, buf)))
+  if (!read_func(data, p, sector, buf, size))
 {
   grub_crypto_xor (buf, buf, pbuf, size);
   goto quit;
 }
 
   grub_errno = GRUB_ERR_NONE;
-  if (grub_diskfilter_read_node (>nodes[q], sector,
-size >> GRUB_DISK_SECTOR_BITS, buf))
+  if (read_func(data, q, sector, buf, size))
 goto quit;
 
   grub_crypto_xor (buf, buf, qbuf, size);
@@ -160,14 +169,12 @@ grub_raid6_recover (struct grub_diskfilter_segment 
*array, int disknr, int p,
   /* Two bad devices */
   unsigned c;
 
-  if (grub_diskfilter_read_node (>nodes[p], sector,
-size >> GRUB_DISK_SECTOR_BITS, buf))
+  if (read_func(data, p, sector, buf, size))
 goto quit;
 
   grub_crypto_xor (pbuf, pbuf, buf, size);
 
-  if (grub_diskfilter_read_node (>nodes[q], sector,
-size >> GRUB_DISK_SECTOR_BITS, buf))
+  if (read_func(data, q, sector, buf, size))
 goto quit;
 
   grub_crypto_xor (qbuf, qbuf, buf, size);
@@ -190,6 +197,15 @@ quit:
   return grub_errno;
 }
 
+static grub_err_t
+grub_raid6_recover (struct grub_diskfilter_segment *array, int disknr, int p,
+char *buf, grub_disk_addr_t sector, grub_size_t size)
+{
+  return grub_raid6_recover_gen (array, array->node_count, disknr, p, buf,
+sector, size << GRUB_DISK_SECTOR_BITS,
+

[PATCH 8/9] btrfs: Make more generic the code for RAID 6 rebuilding

[Goffredo Baroncelli]

From: Goffredo Baroncelli 

The original code which handles the recovery of a RAID 6 disks array
assumes that all reads are multiple of 1 << GRUB_DISK_SECTOR_BITS and it
assumes that all the I/O is done via the struct grub_diskfilter_segment.
This is not true for the btrfs code. In order to reuse the native
grub_raid6_recover() code, it is modified to not call
grub_diskfilter_read_node() directly, but to call an handler passed
as an argument.

Signed-off-by: Goffredo Baroncelli 
Reviewed-by: Daniel Kiper 
---
 grub-core/disk/raid6_recover.c | 52 ++
 include/grub/diskfilter.h  |  9 ++
 2 files changed, 43 insertions(+), 18 deletions(-)

diff --git a/grub-core/disk/raid6_recover.c b/grub-core/disk/raid6_recover.c
index aa674f6ca..0cf691ddf 100644
--- a/grub-core/disk/raid6_recover.c
+++ b/grub-core/disk/raid6_recover.c
@@ -74,14 +74,26 @@ mod_255 (unsigned x)
 }
 
 static grub_err_t
-grub_raid6_recover (struct grub_diskfilter_segment *array, int disknr, int p,
-char *buf, grub_disk_addr_t sector, grub_size_t size)
+raid6_recover_read_node (void *data, int disknr,
+   grub_uint64_t sector,
+   void *buf, grub_size_t size)
+{
+struct grub_diskfilter_segment *array = data;
+
+return grub_diskfilter_read_node (>nodes[disknr],
+ (grub_disk_addr_t)sector,
+ size >> GRUB_DISK_SECTOR_BITS, buf);
+}
+
+grub_err_t
+grub_raid6_recover_gen (void *data, grub_uint64_t nstripes, int disknr, int p,
+   char *buf, grub_uint64_t sector, grub_size_t size,
+   int layout, raid_recover_read_t read_func)
 {
   int i, q, pos;
   int bad1 = -1, bad2 = -1;
   char *pbuf = 0, *qbuf = 0;
 
-  size <<= GRUB_DISK_SECTOR_BITS;
   pbuf = grub_zalloc (size);
   if (!pbuf)
 goto quit;
@@ -91,17 +103,17 @@ grub_raid6_recover (struct grub_diskfilter_segment *array, 
int disknr, int p,
 goto quit;
 
   q = p + 1;
-  if (q == (int) array->node_count)
+  if (q == (int) nstripes)
 q = 0;
 
   pos = q + 1;
-  if (pos == (int) array->node_count)
+  if (pos == (int) nstripes)
 pos = 0;
 
-  for (i = 0; i < (int) array->node_count - 2; i++)
+  for (i = 0; i < (int) nstripes - 2; i++)
 {
   int c;
-  if (array->layout & GRUB_RAID_LAYOUT_MUL_FROM_POS)
+  if (layout & GRUB_RAID_LAYOUT_MUL_FROM_POS)
c = pos;
   else
c = i;
@@ -109,8 +121,7 @@ grub_raid6_recover (struct grub_diskfilter_segment *array, 
int disknr, int p,
 bad1 = c;
   else
 {
-  if (! grub_diskfilter_read_node (>nodes[pos], sector,
-  size >> GRUB_DISK_SECTOR_BITS, buf))
+ if (!read_func(data, pos, sector, buf, size))
 {
   grub_crypto_xor (pbuf, pbuf, buf, size);
   grub_raid_block_mulx (c, buf, size);
@@ -128,7 +139,7 @@ grub_raid6_recover (struct grub_diskfilter_segment *array, 
int disknr, int p,
 }
 
   pos++;
-  if (pos == (int) array->node_count)
+  if (pos == (int) nstripes)
 pos = 0;
 }
 
@@ -139,16 +150,14 @@ grub_raid6_recover (struct grub_diskfilter_segment 
*array, int disknr, int p,
   if (bad2 < 0)
 {
   /* One bad device */
-  if ((! grub_diskfilter_read_node (>nodes[p], sector,
-   size >> GRUB_DISK_SECTOR_BITS, buf)))
+  if (!read_func(data, p, sector, buf, size))
 {
   grub_crypto_xor (buf, buf, pbuf, size);
   goto quit;
 }
 
   grub_errno = GRUB_ERR_NONE;
-  if (grub_diskfilter_read_node (>nodes[q], sector,
-size >> GRUB_DISK_SECTOR_BITS, buf))
+  if (read_func(data, q, sector, buf, size))
 goto quit;
 
   grub_crypto_xor (buf, buf, qbuf, size);
@@ -160,14 +169,12 @@ grub_raid6_recover (struct grub_diskfilter_segment 
*array, int disknr, int p,
   /* Two bad devices */
   unsigned c;
 
-  if (grub_diskfilter_read_node (>nodes[p], sector,
-size >> GRUB_DISK_SECTOR_BITS, buf))
+  if (read_func(data, p, sector, buf, size))
 goto quit;
 
   grub_crypto_xor (pbuf, pbuf, buf, size);
 
-  if (grub_diskfilter_read_node (>nodes[q], sector,
-size >> GRUB_DISK_SECTOR_BITS, buf))
+  if (read_func(data, q, sector, buf, size))
 goto quit;
 
   grub_crypto_xor (qbuf, qbuf, buf, size);
@@ -190,6 +197,15 @@ quit:
   return grub_errno;
 }
 
+static grub_err_t
+grub_raid6_recover (struct grub_diskfilter_segment *array, int disknr, int p,
+char *buf, grub_disk_addr_t sector, grub_size_t size)
+{
+  return grub_raid6_recover_gen (array, array->node_count, disknr, p, buf,
+sector, size << GRUB_DISK_SECTOR_BITS,
+

Re: [PATCH 8/9] btrfs: Make more generic the code for RAID 6 rebuilding

[Daniel Kiper]

On Tue, Jun 19, 2018 at 07:39:55PM +0200, Goffredo Baroncelli wrote:
> The original code which handles the recovery of a RAID 6 disks array
> assumes that all reads are multiple of 1 << GRUB_DISK_SECTOR_BITS and it
> assumes that all the I/O is done via the struct grub_diskfilter_segment.
> This is not true for the btrfs code. In order to reuse the native
> grub_raid6_recover() code, it is modified to not call
> grub_diskfilter_read_node() directly, but to call an handler passed
> as an argument.
>
> Signed-off-by: Goffredo Baroncelli 

Reviewed-by: Daniel Kiper 

Daniel

___
Grub-devel mailing list
Grub-devel@gnu.org
https://lists.gnu.org/mailman/listinfo/grub-devel

[PATCH 8/9] btrfs: Make more generic the code for RAID 6 rebuilding

[Goffredo Baroncelli]

The original code which handles the recovery of a RAID 6 disks array
assumes that all reads are multiple of 1 << GRUB_DISK_SECTOR_BITS and it
assumes that all the I/O is done via the struct grub_diskfilter_segment.
This is not true for the btrfs code. In order to reuse the native
grub_raid6_recover() code, it is modified to not call
grub_diskfilter_read_node() directly, but to call an handler passed
as an argument.

Signed-off-by: Goffredo Baroncelli 
---
 grub-core/disk/raid6_recover.c | 52 ++
 include/grub/diskfilter.h  |  9 ++
 2 files changed, 43 insertions(+), 18 deletions(-)

diff --git a/grub-core/disk/raid6_recover.c b/grub-core/disk/raid6_recover.c
index aa674f6ca..0cf691ddf 100644
--- a/grub-core/disk/raid6_recover.c
+++ b/grub-core/disk/raid6_recover.c
@@ -74,14 +74,26 @@ mod_255 (unsigned x)
 }
 
 static grub_err_t
-grub_raid6_recover (struct grub_diskfilter_segment *array, int disknr, int p,
-char *buf, grub_disk_addr_t sector, grub_size_t size)
+raid6_recover_read_node (void *data, int disknr,
+   grub_uint64_t sector,
+   void *buf, grub_size_t size)
+{
+struct grub_diskfilter_segment *array = data;
+
+return grub_diskfilter_read_node (>nodes[disknr],
+ (grub_disk_addr_t)sector,
+ size >> GRUB_DISK_SECTOR_BITS, buf);
+}
+
+grub_err_t
+grub_raid6_recover_gen (void *data, grub_uint64_t nstripes, int disknr, int p,
+   char *buf, grub_uint64_t sector, grub_size_t size,
+   int layout, raid_recover_read_t read_func)
 {
   int i, q, pos;
   int bad1 = -1, bad2 = -1;
   char *pbuf = 0, *qbuf = 0;
 
-  size <<= GRUB_DISK_SECTOR_BITS;
   pbuf = grub_zalloc (size);
   if (!pbuf)
 goto quit;
@@ -91,17 +103,17 @@ grub_raid6_recover (struct grub_diskfilter_segment *array, 
int disknr, int p,
 goto quit;
 
   q = p + 1;
-  if (q == (int) array->node_count)
+  if (q == (int) nstripes)
 q = 0;
 
   pos = q + 1;
-  if (pos == (int) array->node_count)
+  if (pos == (int) nstripes)
 pos = 0;
 
-  for (i = 0; i < (int) array->node_count - 2; i++)
+  for (i = 0; i < (int) nstripes - 2; i++)
 {
   int c;
-  if (array->layout & GRUB_RAID_LAYOUT_MUL_FROM_POS)
+  if (layout & GRUB_RAID_LAYOUT_MUL_FROM_POS)
c = pos;
   else
c = i;
@@ -109,8 +121,7 @@ grub_raid6_recover (struct grub_diskfilter_segment *array, 
int disknr, int p,
 bad1 = c;
   else
 {
-  if (! grub_diskfilter_read_node (>nodes[pos], sector,
-  size >> GRUB_DISK_SECTOR_BITS, buf))
+ if (!read_func(data, pos, sector, buf, size))
 {
   grub_crypto_xor (pbuf, pbuf, buf, size);
   grub_raid_block_mulx (c, buf, size);
@@ -128,7 +139,7 @@ grub_raid6_recover (struct grub_diskfilter_segment *array, 
int disknr, int p,
 }
 
   pos++;
-  if (pos == (int) array->node_count)
+  if (pos == (int) nstripes)
 pos = 0;
 }
 
@@ -139,16 +150,14 @@ grub_raid6_recover (struct grub_diskfilter_segment 
*array, int disknr, int p,
   if (bad2 < 0)
 {
   /* One bad device */
-  if ((! grub_diskfilter_read_node (>nodes[p], sector,
-   size >> GRUB_DISK_SECTOR_BITS, buf)))
+  if (!read_func(data, p, sector, buf, size))
 {
   grub_crypto_xor (buf, buf, pbuf, size);
   goto quit;
 }
 
   grub_errno = GRUB_ERR_NONE;
-  if (grub_diskfilter_read_node (>nodes[q], sector,
-size >> GRUB_DISK_SECTOR_BITS, buf))
+  if (read_func(data, q, sector, buf, size))
 goto quit;
 
   grub_crypto_xor (buf, buf, qbuf, size);
@@ -160,14 +169,12 @@ grub_raid6_recover (struct grub_diskfilter_segment 
*array, int disknr, int p,
   /* Two bad devices */
   unsigned c;
 
-  if (grub_diskfilter_read_node (>nodes[p], sector,
-size >> GRUB_DISK_SECTOR_BITS, buf))
+  if (read_func(data, p, sector, buf, size))
 goto quit;
 
   grub_crypto_xor (pbuf, pbuf, buf, size);
 
-  if (grub_diskfilter_read_node (>nodes[q], sector,
-size >> GRUB_DISK_SECTOR_BITS, buf))
+  if (read_func(data, q, sector, buf, size))
 goto quit;
 
   grub_crypto_xor (qbuf, qbuf, buf, size);
@@ -190,6 +197,15 @@ quit:
   return grub_errno;
 }
 
+static grub_err_t
+grub_raid6_recover (struct grub_diskfilter_segment *array, int disknr, int p,
+char *buf, grub_disk_addr_t sector, grub_size_t size)
+{
+  return grub_raid6_recover_gen (array, array->node_count, disknr, p, buf,
+sector, size << GRUB_DISK_SECTOR_BITS,
+array->layout, raid6_recover_read_node);

[PATCH 8/9] btrfs: Make more generic the code for RAID 6 rebuilding

[Goffredo Baroncelli]

The original code which handles the recovery of a RAID 6 disks array
assumes that all reads are multiple of 1 << GRUB_DISK_SECTOR_BITS and it
assumes that all the I/O is done via the struct grub_diskfilter_segment.
This is not true for the btrfs code. In order to reuse the native
grub_raid6_recover() code, it is modified to not call
grub_diskfilter_read_node() directly, but to call an handler passed
as an argument.

Signed-off-by: Goffredo Baroncelli 
---
 grub-core/disk/raid6_recover.c | 52 ++
 include/grub/diskfilter.h  |  9 ++
 2 files changed, 43 insertions(+), 18 deletions(-)

diff --git a/grub-core/disk/raid6_recover.c b/grub-core/disk/raid6_recover.c
index aa674f6ca..0cf691ddf 100644
--- a/grub-core/disk/raid6_recover.c
+++ b/grub-core/disk/raid6_recover.c
@@ -74,14 +74,26 @@ mod_255 (unsigned x)
 }
 
 static grub_err_t
-grub_raid6_recover (struct grub_diskfilter_segment *array, int disknr, int p,
-char *buf, grub_disk_addr_t sector, grub_size_t size)
+raid6_recover_read_node (void *data, int disknr,
+   grub_uint64_t sector,
+   void *buf, grub_size_t size)
+{
+struct grub_diskfilter_segment *array = data;
+
+return grub_diskfilter_read_node (>nodes[disknr],
+ (grub_disk_addr_t)sector,
+ size >> GRUB_DISK_SECTOR_BITS, buf);
+}
+
+grub_err_t
+grub_raid6_recover_gen (void *data, grub_uint64_t nstripes, int disknr, int p,
+   char *buf, grub_uint64_t sector, grub_size_t size,
+   int layout, raid_recover_read_t read_func)
 {
   int i, q, pos;
   int bad1 = -1, bad2 = -1;
   char *pbuf = 0, *qbuf = 0;
 
-  size <<= GRUB_DISK_SECTOR_BITS;
   pbuf = grub_zalloc (size);
   if (!pbuf)
 goto quit;
@@ -91,17 +103,17 @@ grub_raid6_recover (struct grub_diskfilter_segment *array, 
int disknr, int p,
 goto quit;
 
   q = p + 1;
-  if (q == (int) array->node_count)
+  if (q == (int) nstripes)
 q = 0;
 
   pos = q + 1;
-  if (pos == (int) array->node_count)
+  if (pos == (int) nstripes)
 pos = 0;
 
-  for (i = 0; i < (int) array->node_count - 2; i++)
+  for (i = 0; i < (int) nstripes - 2; i++)
 {
   int c;
-  if (array->layout & GRUB_RAID_LAYOUT_MUL_FROM_POS)
+  if (layout & GRUB_RAID_LAYOUT_MUL_FROM_POS)
c = pos;
   else
c = i;
@@ -109,8 +121,7 @@ grub_raid6_recover (struct grub_diskfilter_segment *array, 
int disknr, int p,
 bad1 = c;
   else
 {
-  if (! grub_diskfilter_read_node (>nodes[pos], sector,
-  size >> GRUB_DISK_SECTOR_BITS, buf))
+ if (!read_func(data, pos, sector, buf, size))
 {
   grub_crypto_xor (pbuf, pbuf, buf, size);
   grub_raid_block_mulx (c, buf, size);
@@ -128,7 +139,7 @@ grub_raid6_recover (struct grub_diskfilter_segment *array, 
int disknr, int p,
 }
 
   pos++;
-  if (pos == (int) array->node_count)
+  if (pos == (int) nstripes)
 pos = 0;
 }
 
@@ -139,16 +150,14 @@ grub_raid6_recover (struct grub_diskfilter_segment 
*array, int disknr, int p,
   if (bad2 < 0)
 {
   /* One bad device */
-  if ((! grub_diskfilter_read_node (>nodes[p], sector,
-   size >> GRUB_DISK_SECTOR_BITS, buf)))
+  if (!read_func(data, p, sector, buf, size))
 {
   grub_crypto_xor (buf, buf, pbuf, size);
   goto quit;
 }
 
   grub_errno = GRUB_ERR_NONE;
-  if (grub_diskfilter_read_node (>nodes[q], sector,
-size >> GRUB_DISK_SECTOR_BITS, buf))
+  if (read_func(data, q, sector, buf, size))
 goto quit;
 
   grub_crypto_xor (buf, buf, qbuf, size);
@@ -160,14 +169,12 @@ grub_raid6_recover (struct grub_diskfilter_segment 
*array, int disknr, int p,
   /* Two bad devices */
   unsigned c;
 
-  if (grub_diskfilter_read_node (>nodes[p], sector,
-size >> GRUB_DISK_SECTOR_BITS, buf))
+  if (read_func(data, p, sector, buf, size))
 goto quit;
 
   grub_crypto_xor (pbuf, pbuf, buf, size);
 
-  if (grub_diskfilter_read_node (>nodes[q], sector,
-size >> GRUB_DISK_SECTOR_BITS, buf))
+  if (read_func(data, q, sector, buf, size))
 goto quit;
 
   grub_crypto_xor (qbuf, qbuf, buf, size);
@@ -190,6 +197,15 @@ quit:
   return grub_errno;
 }
 
+static grub_err_t
+grub_raid6_recover (struct grub_diskfilter_segment *array, int disknr, int p,
+char *buf, grub_disk_addr_t sector, grub_size_t size)
+{
+  return grub_raid6_recover_gen (array, array->node_count, disknr, p, buf,
+sector, size << GRUB_DISK_SECTOR_BITS,
+array->layout, raid6_recover_read_node);

Re: [PATCH 8/9] btrfs: make more generic the code for RAID 6 rebuilding

[Goffredo Baroncelli]

On 05/30/2018 02:05 PM, Daniel Kiper wrote:
> On Wed, May 16, 2018 at 08:48:18PM +0200, Goffredo Baroncelli wrote:
>> The original code which handles the recovery of a RAID 6 disks array
>> assumes that all reads are multiple of 1 << GRUB_DISK_SECTOR_BITS and it
>> assumes that all the I/O is done via the struct grub_diskfilter_segment.
>> This is not true for the btrfs code. In order to reuse the native
>> grub_raid6_recover() code, it is modified to not call
>> grub_diskfilter_read_node() directly, but to call an handler passed
>> as argument.
> 
> s/as argument/as an argument/
ok
> 
>> Signed-off-by: Goffredo Baroncelli 
>> ---
>>  grub-core/disk/raid6_recover.c | 53 ++
>>  include/grub/diskfilter.h  |  9 ++
>>  2 files changed, 44 insertions(+), 18 deletions(-)
>>
>> diff --git a/grub-core/disk/raid6_recover.c b/grub-core/disk/raid6_recover.c
>> index aa674f6ca..10ee495e2 100644
>> --- a/grub-core/disk/raid6_recover.c
>> +++ b/grub-core/disk/raid6_recover.c
>> @@ -74,14 +74,25 @@ mod_255 (unsigned x)
>>  }
>>
>>  static grub_err_t
>> -grub_raid6_recover (struct grub_diskfilter_segment *array, int disknr, int 
>> p,
>> -char *buf, grub_disk_addr_t sector, grub_size_t size)
>> +raid6_recover_read_node (void *data, int disk_nr,
> 
> s/disk_nr/disknr/

OK

>> +grub_uint64_t sector,
>> +void *buf, grub_size_t size)
>> +{
>> +struct grub_diskfilter_segment *array = data;
> 
> Please add one empty line here.
> 
>> +return grub_diskfilter_read_node (>nodes[disk_nr],
>> +  (grub_disk_addr_t)sector,
>> +  size >> GRUB_DISK_SECTOR_BITS, buf);
>> +}
>> +
>> +grub_err_t
>> +grub_raid6_recover_gen (void *data, grub_uint64_t nstripes, int disknr, int 
>> p,
>> +char *buf, grub_uint64_t sector, grub_size_t size,
>> +raid_recover_read_t read_func, int layout)
> 
> Could you change the order of read_func and layout arguments?
> I mean make read_func the last one and put the layout before it.
OK
> 
>>  {
>>int i, q, pos;
>>int bad1 = -1, bad2 = -1;
>>char *pbuf = 0, *qbuf = 0;
>>
>> -  size <<= GRUB_DISK_SECTOR_BITS;
>>pbuf = grub_zalloc (size);
>>if (!pbuf)
>>  goto quit;
>> @@ -91,17 +102,17 @@ grub_raid6_recover (struct grub_diskfilter_segment 
>> *array, int disknr, int p,
>>  goto quit;
>>
>>q = p + 1;
>> -  if (q == (int) array->node_count)
>> +  if (q == (int) nstripes)
>>  q = 0;
>>
>>pos = q + 1;
>> -  if (pos == (int) array->node_count)
>> +  if (pos == (int) nstripes)
>>  pos = 0;
>>
>> -  for (i = 0; i < (int) array->node_count - 2; i++)
>> +  for (i = 0; i < (int) nstripes - 2; i++)
>>  {
>>int c;
>> -  if (array->layout & GRUB_RAID_LAYOUT_MUL_FROM_POS)
>> +  if (layout & GRUB_RAID_LAYOUT_MUL_FROM_POS)
>>  c = pos;
>>else
>>  c = i;
>> @@ -109,8 +120,7 @@ grub_raid6_recover (struct grub_diskfilter_segment 
>> *array, int disknr, int p,
>>  bad1 = c;
>>else
>>  {
>> -  if (! grub_diskfilter_read_node (>nodes[pos], sector,
>> -   size >> GRUB_DISK_SECTOR_BITS, buf))
>> +  if (!read_func(data, pos, sector, buf, size))
>>  {
>>grub_crypto_xor (pbuf, pbuf, buf, size);
>>grub_raid_block_mulx (c, buf, size);
>> @@ -128,7 +138,7 @@ grub_raid6_recover (struct grub_diskfilter_segment 
>> *array, int disknr, int p,
>>  }
>>
>>pos++;
>> -  if (pos == (int) array->node_count)
>> +  if (pos == (int) nstripes)
>>  pos = 0;
>>  }
>>
>> @@ -139,16 +149,14 @@ grub_raid6_recover (struct grub_diskfilter_segment 
>> *array, int disknr, int p,
>>if (bad2 < 0)
>>  {
>>/* One bad device */
>> -  if ((! grub_diskfilter_read_node (>nodes[p], sector,
>> -size >> GRUB_DISK_SECTOR_BITS, buf)))
>> +  if (!read_func(data, p, sector, buf, size))
>>  {
>>grub_crypto_xor (buf, buf, pbuf, size);
>>goto quit;
>>  }
>>
>>grub_errno = GRUB_ERR_NONE;
>> -  if (grub_diskfilter_read_node (>nodes[q], sector,
>> - size >> GRUB_DISK_SECTOR_BITS, buf))
>> +  if (read_func(data, q, sector, buf, size))
>>  goto quit;
>>
>>grub_crypto_xor (buf, buf, qbuf, size);
>> @@ -160,14 +168,12 @@ grub_raid6_recover (struct grub_diskfilter_segment 
>> *array, int disknr, int p,
>>/* Two bad devices */
>>unsigned c;
>>
>> -  if (grub_diskfilter_read_node (>nodes[p], sector,
>> - size >> GRUB_DISK_SECTOR_BITS, buf))
>> +  if (read_func(data, p, sector, buf, size))
>>  goto quit;
>>
>>grub_crypto_xor (pbuf, pbuf, buf, size);
>>
>> -  if (grub_diskfilter_read_node 

Re: [PATCH 8/9] btrfs: make more generic the code for RAID 6 rebuilding

[Daniel Kiper]

On Wed, May 16, 2018 at 08:48:18PM +0200, Goffredo Baroncelli wrote:
> The original code which handles the recovery of a RAID 6 disks array
> assumes that all reads are multiple of 1 << GRUB_DISK_SECTOR_BITS and it
> assumes that all the I/O is done via the struct grub_diskfilter_segment.
> This is not true for the btrfs code. In order to reuse the native
> grub_raid6_recover() code, it is modified to not call
> grub_diskfilter_read_node() directly, but to call an handler passed
> as argument.

s/as argument/as an argument/

> Signed-off-by: Goffredo Baroncelli 
> ---
>  grub-core/disk/raid6_recover.c | 53 ++
>  include/grub/diskfilter.h  |  9 ++
>  2 files changed, 44 insertions(+), 18 deletions(-)
>
> diff --git a/grub-core/disk/raid6_recover.c b/grub-core/disk/raid6_recover.c
> index aa674f6ca..10ee495e2 100644
> --- a/grub-core/disk/raid6_recover.c
> +++ b/grub-core/disk/raid6_recover.c
> @@ -74,14 +74,25 @@ mod_255 (unsigned x)
>  }
>
>  static grub_err_t
> -grub_raid6_recover (struct grub_diskfilter_segment *array, int disknr, int p,
> -char *buf, grub_disk_addr_t sector, grub_size_t size)
> +raid6_recover_read_node (void *data, int disk_nr,

s/disk_nr/disknr/

> + grub_uint64_t sector,
> + void *buf, grub_size_t size)
> +{
> +struct grub_diskfilter_segment *array = data;

Please add one empty line here.

> +return grub_diskfilter_read_node (>nodes[disk_nr],
> +   (grub_disk_addr_t)sector,
> +   size >> GRUB_DISK_SECTOR_BITS, buf);
> +}
> +
> +grub_err_t
> +grub_raid6_recover_gen (void *data, grub_uint64_t nstripes, int disknr, int 
> p,
> + char *buf, grub_uint64_t sector, grub_size_t size,
> + raid_recover_read_t read_func, int layout)

Could you change the order of read_func and layout arguments?
I mean make read_func the last one and put the layout before it.

>  {
>int i, q, pos;
>int bad1 = -1, bad2 = -1;
>char *pbuf = 0, *qbuf = 0;
>
> -  size <<= GRUB_DISK_SECTOR_BITS;
>pbuf = grub_zalloc (size);
>if (!pbuf)
>  goto quit;
> @@ -91,17 +102,17 @@ grub_raid6_recover (struct grub_diskfilter_segment 
> *array, int disknr, int p,
>  goto quit;
>
>q = p + 1;
> -  if (q == (int) array->node_count)
> +  if (q == (int) nstripes)
>  q = 0;
>
>pos = q + 1;
> -  if (pos == (int) array->node_count)
> +  if (pos == (int) nstripes)
>  pos = 0;
>
> -  for (i = 0; i < (int) array->node_count - 2; i++)
> +  for (i = 0; i < (int) nstripes - 2; i++)
>  {
>int c;
> -  if (array->layout & GRUB_RAID_LAYOUT_MUL_FROM_POS)
> +  if (layout & GRUB_RAID_LAYOUT_MUL_FROM_POS)
>   c = pos;
>else
>   c = i;
> @@ -109,8 +120,7 @@ grub_raid6_recover (struct grub_diskfilter_segment 
> *array, int disknr, int p,
>  bad1 = c;
>else
>  {
> -  if (! grub_diskfilter_read_node (>nodes[pos], sector,
> -size >> GRUB_DISK_SECTOR_BITS, buf))
> +   if (!read_func(data, pos, sector, buf, size))
>  {
>grub_crypto_xor (pbuf, pbuf, buf, size);
>grub_raid_block_mulx (c, buf, size);
> @@ -128,7 +138,7 @@ grub_raid6_recover (struct grub_diskfilter_segment 
> *array, int disknr, int p,
>  }
>
>pos++;
> -  if (pos == (int) array->node_count)
> +  if (pos == (int) nstripes)
>  pos = 0;
>  }
>
> @@ -139,16 +149,14 @@ grub_raid6_recover (struct grub_diskfilter_segment 
> *array, int disknr, int p,
>if (bad2 < 0)
>  {
>/* One bad device */
> -  if ((! grub_diskfilter_read_node (>nodes[p], sector,
> - size >> GRUB_DISK_SECTOR_BITS, buf)))
> +  if (!read_func(data, p, sector, buf, size))
>  {
>grub_crypto_xor (buf, buf, pbuf, size);
>goto quit;
>  }
>
>grub_errno = GRUB_ERR_NONE;
> -  if (grub_diskfilter_read_node (>nodes[q], sector,
> -  size >> GRUB_DISK_SECTOR_BITS, buf))
> +  if (read_func(data, q, sector, buf, size))
>  goto quit;
>
>grub_crypto_xor (buf, buf, qbuf, size);
> @@ -160,14 +168,12 @@ grub_raid6_recover (struct grub_diskfilter_segment 
> *array, int disknr, int p,
>/* Two bad devices */
>unsigned c;
>
> -  if (grub_diskfilter_read_node (>nodes[p], sector,
> -  size >> GRUB_DISK_SECTOR_BITS, buf))
> +  if (read_func(data, p, sector, buf, size))
>  goto quit;
>
>grub_crypto_xor (pbuf, pbuf, buf, size);
>
> -  if (grub_diskfilter_read_node (>nodes[q], sector,
> -  size >> GRUB_DISK_SECTOR_BITS, buf))
> +  if (read_func(data, q, sector, buf, size))
>  goto quit;
>
>grub_crypto_xor 

[PATCH 8/9] btrfs: make more generic the code for RAID 6 rebuilding

[Goffredo Baroncelli]

The original code which handles the recovery of a RAID 6 disks array
assumes that all reads are multiple of 1 << GRUB_DISK_SECTOR_BITS and it
assumes that all the I/O is done via the struct grub_diskfilter_segment.
This is not true for the btrfs code. In order to reuse the native
grub_raid6_recover() code, it is modified to not call
grub_diskfilter_read_node() directly, but to call an handler passed
as argument.

Signed-off-by: Goffredo Baroncelli 
---
 grub-core/disk/raid6_recover.c | 53 ++
 include/grub/diskfilter.h  |  9 ++
 2 files changed, 44 insertions(+), 18 deletions(-)

diff --git a/grub-core/disk/raid6_recover.c b/grub-core/disk/raid6_recover.c
index aa674f6ca..10ee495e2 100644
--- a/grub-core/disk/raid6_recover.c
+++ b/grub-core/disk/raid6_recover.c
@@ -74,14 +74,25 @@ mod_255 (unsigned x)
 }
 
 static grub_err_t
-grub_raid6_recover (struct grub_diskfilter_segment *array, int disknr, int p,
-char *buf, grub_disk_addr_t sector, grub_size_t size)
+raid6_recover_read_node (void *data, int disk_nr,
+   grub_uint64_t sector,
+   void *buf, grub_size_t size)
+{
+struct grub_diskfilter_segment *array = data;
+return grub_diskfilter_read_node (>nodes[disk_nr],
+ (grub_disk_addr_t)sector,
+ size >> GRUB_DISK_SECTOR_BITS, buf);
+}
+
+grub_err_t
+grub_raid6_recover_gen (void *data, grub_uint64_t nstripes, int disknr, int p,
+   char *buf, grub_uint64_t sector, grub_size_t size,
+   raid_recover_read_t read_func, int layout)
 {
   int i, q, pos;
   int bad1 = -1, bad2 = -1;
   char *pbuf = 0, *qbuf = 0;
 
-  size <<= GRUB_DISK_SECTOR_BITS;
   pbuf = grub_zalloc (size);
   if (!pbuf)
 goto quit;
@@ -91,17 +102,17 @@ grub_raid6_recover (struct grub_diskfilter_segment *array, 
int disknr, int p,
 goto quit;
 
   q = p + 1;
-  if (q == (int) array->node_count)
+  if (q == (int) nstripes)
 q = 0;
 
   pos = q + 1;
-  if (pos == (int) array->node_count)
+  if (pos == (int) nstripes)
 pos = 0;
 
-  for (i = 0; i < (int) array->node_count - 2; i++)
+  for (i = 0; i < (int) nstripes - 2; i++)
 {
   int c;
-  if (array->layout & GRUB_RAID_LAYOUT_MUL_FROM_POS)
+  if (layout & GRUB_RAID_LAYOUT_MUL_FROM_POS)
c = pos;
   else
c = i;
@@ -109,8 +120,7 @@ grub_raid6_recover (struct grub_diskfilter_segment *array, 
int disknr, int p,
 bad1 = c;
   else
 {
-  if (! grub_diskfilter_read_node (>nodes[pos], sector,
-  size >> GRUB_DISK_SECTOR_BITS, buf))
+ if (!read_func(data, pos, sector, buf, size))
 {
   grub_crypto_xor (pbuf, pbuf, buf, size);
   grub_raid_block_mulx (c, buf, size);
@@ -128,7 +138,7 @@ grub_raid6_recover (struct grub_diskfilter_segment *array, 
int disknr, int p,
 }
 
   pos++;
-  if (pos == (int) array->node_count)
+  if (pos == (int) nstripes)
 pos = 0;
 }
 
@@ -139,16 +149,14 @@ grub_raid6_recover (struct grub_diskfilter_segment 
*array, int disknr, int p,
   if (bad2 < 0)
 {
   /* One bad device */
-  if ((! grub_diskfilter_read_node (>nodes[p], sector,
-   size >> GRUB_DISK_SECTOR_BITS, buf)))
+  if (!read_func(data, p, sector, buf, size))
 {
   grub_crypto_xor (buf, buf, pbuf, size);
   goto quit;
 }
 
   grub_errno = GRUB_ERR_NONE;
-  if (grub_diskfilter_read_node (>nodes[q], sector,
-size >> GRUB_DISK_SECTOR_BITS, buf))
+  if (read_func(data, q, sector, buf, size))
 goto quit;
 
   grub_crypto_xor (buf, buf, qbuf, size);
@@ -160,14 +168,12 @@ grub_raid6_recover (struct grub_diskfilter_segment 
*array, int disknr, int p,
   /* Two bad devices */
   unsigned c;
 
-  if (grub_diskfilter_read_node (>nodes[p], sector,
-size >> GRUB_DISK_SECTOR_BITS, buf))
+  if (read_func(data, p, sector, buf, size))
 goto quit;
 
   grub_crypto_xor (pbuf, pbuf, buf, size);
 
-  if (grub_diskfilter_read_node (>nodes[q], sector,
-size >> GRUB_DISK_SECTOR_BITS, buf))
+  if (read_func(data, q, sector, buf, size))
 goto quit;
 
   grub_crypto_xor (qbuf, qbuf, buf, size);
@@ -190,6 +196,17 @@ quit:
   return grub_errno;
 }
 
+static grub_err_t
+grub_raid6_recover (struct grub_diskfilter_segment *array, int disknr, int p,
+char *buf, grub_disk_addr_t sector, grub_size_t size)
+{
+
+  return grub_raid6_recover_gen (array, array->node_count, disknr, p, buf,
+sector, size << GRUB_DISK_SECTOR_BITS,
+