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, 46 insertions, 0 deletions

diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
new file mode 100644
index 000000000..8efbcf699
--- /dev/null
+++ b/drivers/firmware/efi/Makefile
@@ -0,0 +1,46 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for linux kernel
+#
+
+#
+# ARM64 maps efi runtime services in userspace addresses
+# which don't have KASAN shadow. So dereference of these addresses
+# in efi_call_virt() will cause crash if this code instrumented.
+#
+KASAN_SANITIZE_runtime-wrappers.o	:= n
+
+obj-$(CONFIG_ACPI_BGRT) 		+= efi-bgrt.o
+obj-$(CONFIG_EFI)			+= efi.o vars.o reboot.o memattr.o tpm.o
+obj-$(CONFIG_EFI)			+= memmap.o
+ifneq ($(CONFIG_EFI_CAPSULE_LOADER),)
+obj-$(CONFIG_EFI)			+= capsule.o
+endif
+obj-$(CONFIG_EFI_PARAMS_FROM_FDT)	+= fdtparams.o
+obj-$(CONFIG_EFI_ESRT)			+= esrt.o
+obj-$(CONFIG_EFI_VARS_PSTORE)		+= efi-pstore.o
+obj-$(CONFIG_UEFI_CPER)			+= cper.o cper_cxl.o
+obj-$(CONFIG_EFI_RUNTIME_WRAPPERS)	+= runtime-wrappers.o
+subdir-$(CONFIG_EFI_STUB)		+= libstub
+obj-$(CONFIG_EFI_BOOTLOADER_CONTROL)	+= efibc.o
+obj-$(CONFIG_EFI_TEST)			+= test/
+obj-$(CONFIG_EFI_DEV_PATH_PARSER)	+= dev-path-parser.o
+obj-$(CONFIG_APPLE_PROPERTIES)		+= apple-properties.o
+obj-$(CONFIG_EFI_RCI2_TABLE)		+= rci2-table.o
+obj-$(CONFIG_EFI_EMBEDDED_FIRMWARE)	+= embedded-firmware.o
+obj-$(CONFIG_LOAD_UEFI_KEYS)		+= mokvar-table.o
+obj-$(CONFIG_OVMF_DEBUG_LOG)		+= ovmf-debug-log.o
+
+obj-$(CONFIG_SYSFB)			+= sysfb_efi.o
+
+arm-obj-$(CONFIG_EFI)			:= efi-init.o arm-runtime.o
+obj-$(CONFIG_ARM)			+= $(arm-obj-y)
+obj-$(CONFIG_ARM64)			+= $(arm-obj-y)
+riscv-obj-$(CONFIG_EFI)			:= efi-init.o riscv-runtime.o
+obj-$(CONFIG_RISCV)			+= $(riscv-obj-y)
+obj-$(CONFIG_EFI_CAPSULE_LOADER)	+= capsule-loader.o
+obj-$(CONFIG_EFI_EARLYCON)		+= earlycon.o
+obj-$(CONFIG_UEFI_CPER_ARM)		+= cper-arm.o
+obj-$(CONFIG_UEFI_CPER_X86)		+= cper-x86.o
+obj-$(CONFIG_UNACCEPTED_MEMORY)		+= unaccepted_memory.o
+obj-$(CONFIG_TEE_STMM_EFI)		+= stmm/tee_stmm_efi.o