netfs: zero the tail of a short DIO/unbuffered readgrafted

The buffered read collector zero-fills the tail of a short read that
stops below the inode's i_size (netfs_clear_unread()), so a read that
races an extending write still returns the expected number of bytes.
The non-buffered collector path does no such thing: it just records
how much was transferred.

Add the same zero-fill for the non-buffered case, gated on
NETFS_SREQ_CLEAR_TAIL: a subreq's source sets that flag when a short
result from it is known to be safe to treat as a hole, as opposed to
NETFS_SREQ_HIT_EOF, which means the read genuinely ran off the end of
the file and should be reported short as-is. Only CLEAR_TAIL should
zero-fill here; a real EOF must stay a real short read.

No source currently sets CLEAR_TAIL on an unbuffered/DIO subrequest,
so this is inert on its own -- a following change teaches cifs to set
it in the one case that needs it.

Fixes: e2d46f2ec332 ("netfs: Change the read result collector to only use one work item")
Reviewed-by: David Howells <dhowells@redhat.com>
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Cc: Shyam Prasad N <sprasad@microsoft.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Bharath SM <bharathsm@microsoft.com>
Cc: stable@vger.kernel.org

1 files changed, 128 insertions, 0 deletions

diff --git a/lib/raid/raid6/Makefile b/lib/raid/raid6/Makefile
new file mode 100644
index 000000000..5cdb7223d
--- /dev/null
+++ b/lib/raid/raid6/Makefile
@@ -0,0 +1,128 @@
+# SPDX-License-Identifier: GPL-2.0
+
+CONTEXT_ANALYSIS := y
+
+ccflags-y			+= -I $(src)
+
+ifeq ($(CONFIG_RAID6_PQ_ARCH),y)
+CFLAGS_algos.o			+= -I$(src)/$(SRCARCH)
+endif
+
+obj-$(CONFIG_RAID6_PQ)		+= raid6_pq.o tests/
+
+raid6_pq-y			+= algos.o tables.o
+
+# generic integer generation and recovery implementation
+raid6_pq-y			+= int1.o int2.o int4.o int8.o
+raid6_pq-y			+= recov.o
+
+# architecture-specific generation and recovery implementations:
+raid6_pq-$(CONFIG_KERNEL_MODE_NEON) += arm/neon.o \
+				   arm/neon1.o \
+				   arm/neon2.o \
+				   arm/neon4.o \
+				   arm/neon8.o \
+				   arm/recov_neon.o \
+				   arm/recov_neon_inner.o
+raid6_pq-$(CONFIG_LOONGARCH)	+= loongarch/loongarch_simd.o \
+				   loongarch/recov_loongarch_simd.o
+raid6_pq-$(CONFIG_ALTIVEC)	+= powerpc/altivec1.o \
+				   powerpc/altivec2.o \
+				   powerpc/altivec4.o \
+				   powerpc/altivec8.o \
+				   powerpc/vpermxor1.o \
+				   powerpc/vpermxor2.o \
+				   powerpc/vpermxor4.o \
+				   powerpc/vpermxor8.o
+raid6_pq-$(CONFIG_RISCV_ISA_V)	+= riscv/rvv.o \
+				   riscv/recov_rvv.o
+raid6_pq-$(CONFIG_S390)		+= s390/s390vx8.o \
+				   s390/recov_s390xc.o
+ifeq ($(CONFIG_X86),y)
+raid6_pq-$(CONFIG_X86_32)	+= x86/mmx.o \
+				   x86/sse1.o
+endif
+raid6_pq-$(CONFIG_X86)		+= x86/sse2.o \
+				   x86/avx2.o \
+				   x86/avx512.o \
+				   x86/recov_ssse3.o \
+				   x86/recov_avx2.o \
+				   x86/recov_avx512.o
+
+hostprogs			+= mktables
+
+CFLAGS_arm/neon1.o += $(CC_FLAGS_FPU)
+CFLAGS_arm/neon2.o += $(CC_FLAGS_FPU)
+CFLAGS_arm/neon4.o += $(CC_FLAGS_FPU)
+CFLAGS_arm/neon8.o += $(CC_FLAGS_FPU)
+CFLAGS_arm/recov_neon_inner.o += $(CC_FLAGS_FPU)
+CFLAGS_REMOVE_arm/neon1.o += $(CC_FLAGS_NO_FPU)
+CFLAGS_REMOVE_arm/neon2.o += $(CC_FLAGS_NO_FPU)
+CFLAGS_REMOVE_arm/neon4.o += $(CC_FLAGS_NO_FPU)
+CFLAGS_REMOVE_arm/neon8.o += $(CC_FLAGS_NO_FPU)
+CFLAGS_REMOVE_arm/recov_neon_inner.o += $(CC_FLAGS_NO_FPU)
+
+ifeq ($(CONFIG_ALTIVEC),y)
+altivec_flags := -maltivec $(call cc-option,-mabi=altivec)
+# Enable <altivec.h>
+altivec_flags += -isystem $(shell $(CC) -print-file-name=include)
+
+CFLAGS_powerpc/altivec1.o += $(altivec_flags)
+CFLAGS_powerpc/altivec2.o += $(altivec_flags)
+CFLAGS_powerpc/altivec4.o += $(altivec_flags)
+CFLAGS_powerpc/altivec8.o += $(altivec_flags)
+CFLAGS_powerpc/vpermxor1.o += $(altivec_flags)
+CFLAGS_powerpc/vpermxor2.o += $(altivec_flags)
+CFLAGS_powerpc/vpermxor4.o += $(altivec_flags)
+CFLAGS_powerpc/vpermxor8.o += $(altivec_flags)
+
+ifdef CONFIG_CC_IS_CLANG
+# clang ppc port does not yet support -maltivec when -msoft-float is
+# enabled. A future release of clang will resolve this
+# https://llvm.org/pr31177
+CFLAGS_REMOVE_powerpc/altivec1.o  += -msoft-float
+CFLAGS_REMOVE_powerpc/altivec2.o  += -msoft-float
+CFLAGS_REMOVE_powerpc/altivec4.o  += -msoft-float
+CFLAGS_REMOVE_powerpc/altivec8.o  += -msoft-float
+CFLAGS_REMOVE_powerpc/vpermxor1.o += -msoft-float
+CFLAGS_REMOVE_powerpc/vpermxor2.o += -msoft-float
+CFLAGS_REMOVE_powerpc/vpermxor4.o += -msoft-float
+CFLAGS_REMOVE_powerpc/vpermxor8.o += -msoft-float
+endif # CONFIG_CC_IS_CLANG
+endif # CONFIG_ALTIVEC
+
+quiet_cmd_mktable = TABLE   $@
+      cmd_mktable = $(obj)/mktables > $@
+
+targets += tables.c
+$(obj)/tables.c: $(obj)/mktables FORCE
+	$(call if_changed,mktable)
+
+quiet_cmd_unroll = UNROLL  $@
+      cmd_unroll = $(AWK) -v N=$* -f $(src)/unroll.awk < $< > $@
+
+targets += int1.c int2.c int4.c int8.c
+$(obj)/int%.c: $(src)/int.uc $(src)/unroll.awk FORCE
+	$(call if_changed,unroll)
+
+targets += arm/neon1.c arm/neon2.c arm/neon4.c arm/neon8.c
+$(obj)/arm/neon%.c: $(src)/arm/neon.uc $(src)/unroll.awk FORCE
+	$(call if_changed,unroll)
+
+targets += powerpc/altivec1.c \
+	   powerpc/altivec2.c \
+	   powerpc/altivec4.c \
+	   powerpc/altivec8.c
+$(obj)/powerpc/altivec%.c: $(src)/powerpc/altivec.uc $(src)/unroll.awk FORCE
+	$(call if_changed,unroll)
+
+targets += powerpc/vpermxor1.c \
+	   powerpc/vpermxor2.c \
+	   powerpc/vpermxor4.c \
+	   powerpc/vpermxor8.c
+$(obj)/powerpc/vpermxor%.c: $(src)/powerpc/vpermxor.uc $(src)/unroll.awk FORCE
+	$(call if_changed,unroll)
+
+targets += s390/s390vx8.c
+$(obj)/s390/s390vx%.c: $(src)/s390/s390vx.uc $(src)/unroll.awk FORCE
+	$(call if_changed,unroll)