+ btrfs-use-xor_gen.patch added to mm-nonmm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: btrfs: use xor_gen
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     btrfs-use-xor_gen.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/btrfs-use-xor_gen.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Christoph Hellwig <hch@lst.de>
Subject: btrfs: use xor_gen
Date: Fri, 27 Mar 2026 07:16:57 +0100

Use the new xor_gen helper instead of open coding the loop around
xor_blocks.  This helper is very similar to the existing run_xor helper in
btrfs, except that the destination buffer is passed explicitly.

Link: https://lkml.kernel.org/r/20260327061704.3707577-26-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: David Sterba <dsterba@suse.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chris Mason <clm@fb.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason A. Donenfeld <jason@zx2c4.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Li Nan <linan122@huawei.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Magnus Lindholm <linmag7@gmail.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Song Liu <song@kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Ted Ts'o <tytso@mit.edu>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/btrfs/raid56.c |   27 ++++-----------------------
 1 file changed, 4 insertions(+), 23 deletions(-)

--- a/fs/btrfs/raid56.c~btrfs-use-xor_gen
+++ a/fs/btrfs/raid56.c
@@ -618,26 +618,6 @@ static void cache_rbio(struct btrfs_raid
 }
 
 /*
- * helper function to run the xor_blocks api.  It is only
- * able to do MAX_XOR_BLOCKS at a time, so we need to
- * loop through.
- */
-static void run_xor(void **pages, int src_cnt, ssize_t len)
-{
-	int src_off = 0;
-	int xor_src_cnt = 0;
-	void *dest = pages[src_cnt];
-
-	while(src_cnt > 0) {
-		xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS);
-		xor_blocks(xor_src_cnt, len, dest, pages + src_off);
-
-		src_cnt -= xor_src_cnt;
-		src_off += xor_src_cnt;
-	}
-}
-
-/*
  * Returns true if the bio list inside this rbio covers an entire stripe (no
  * rmw required).
  */
@@ -1434,7 +1414,8 @@ static void generate_pq_vertical_step(st
 	} else {
 		/* raid5 */
 		memcpy(pointers[rbio->nr_data], pointers[0], step);
-		run_xor(pointers + 1, rbio->nr_data - 1, step);
+		xor_gen(pointers[rbio->nr_data], pointers + 1, rbio->nr_data - 1,
+				step);
 	}
 	for (stripe = stripe - 1; stripe >= 0; stripe--)
 		kunmap_local(pointers[stripe]);
@@ -2034,7 +2015,7 @@ pstripe:
 		pointers[rbio->nr_data - 1] = p;
 
 		/* Xor in the rest */
-		run_xor(pointers, rbio->nr_data - 1, step);
+		xor_gen(p, pointers, rbio->nr_data - 1, step);
 	}
 
 cleanup:
@@ -2672,7 +2653,7 @@ static bool verify_one_parity_step(struc
 	} else {
 		/* RAID5. */
 		memcpy(pointers[nr_data], pointers[0], step);
-		run_xor(pointers + 1, nr_data - 1, step);
+		xor_gen(pointers[nr_data], pointers + 1, nr_data - 1, step);
 	}
 
 	/* Check scrubbing parity and repair it. */
_

Patches currently in -mm which might be from hch@lst.de are

xor-assert-that-xor_blocks-is-not-call-from-interrupt-context.patch
arm-xor-remove-in_interrupt-handling.patch
arm64-xor-fix-conflicting-attributes-for-xor_block_template.patch
um-xor-cleanup-xorh.patch
xor-move-to-lib-raid.patch
xor-small-cleanups.patch
xor-cleanup-registration-and-probing.patch
xor-split-xorh.patch
xor-remove-macro-abuse-for-xor-implementation-registrations.patch
xor-move-generic-implementations-out-of-asm-generic-xorh.patch
alpha-move-the-xor-code-to-lib-raid.patch
arm-move-the-xor-code-to-lib-raid.patch
arm64-move-the-xor-code-to-lib-raid.patch
loongarch-move-the-xor-code-to-lib-raid.patch
powerpc-move-the-xor-code-to-lib-raid.patch
riscv-move-the-xor-code-to-lib-raid.patch
sparc-move-the-xor-code-to-lib-raid.patch
s390-move-the-xor-code-to-lib-raid.patch
x86-move-the-xor-code-to-lib-raid.patch
xor-avoid-indirect-calls-for-arm64-optimized-ops.patch
xor-make-xorko-self-contained-in-lib-raid.patch
xor-add-a-better-public-api.patch
xor-add-a-better-public-api-2.patch
async_xor-use-xor_gen.patch
btrfs-use-xor_gen.patch
xor-pass-the-entire-operation-to-the-low-level-ops.patch
xor-use-static_call-for-xor_gen.patch
xor-add-a-kunit-test-case.patch