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

12 files changed, 12 insertions, 0 deletions

diff --git a/scripts/dtc/include-prefixes/arc b/scripts/dtc/include-prefixes/arc
new file mode 120000
index 000000000..5d21b5a69
--- /dev/null
+++ b/scripts/dtc/include-prefixes/arc
@@ -0,0 +1 @@
+../../../arch/arc/boot/dts
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/arm b/scripts/dtc/include-prefixes/arm
new file mode 120000
index 000000000..eb14d4515
--- /dev/null
+++ b/scripts/dtc/include-prefixes/arm
@@ -0,0 +1 @@
+../../../arch/arm/boot/dts
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/arm64 b/scripts/dtc/include-prefixes/arm64
new file mode 120000
index 000000000..275c42c21
--- /dev/null
+++ b/scripts/dtc/include-prefixes/arm64
@@ -0,0 +1 @@
+../../../arch/arm64/boot/dts
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/dt-bindings b/scripts/dtc/include-prefixes/dt-bindings
new file mode 120000
index 000000000..04fdbb3af
--- /dev/null
+++ b/scripts/dtc/include-prefixes/dt-bindings
@@ -0,0 +1 @@
+../../../include/dt-bindings
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/microblaze b/scripts/dtc/include-prefixes/microblaze
new file mode 120000
index 000000000..d9830330a
--- /dev/null
+++ b/scripts/dtc/include-prefixes/microblaze
@@ -0,0 +1 @@
+../../../arch/microblaze/boot/dts
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/mips b/scripts/dtc/include-prefixes/mips
new file mode 120000
index 000000000..ae8d4948d
--- /dev/null
+++ b/scripts/dtc/include-prefixes/mips
@@ -0,0 +1 @@
+../../../arch/mips/boot/dts
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/nios2 b/scripts/dtc/include-prefixes/nios2
new file mode 120000
index 000000000..51772336d
--- /dev/null
+++ b/scripts/dtc/include-prefixes/nios2
@@ -0,0 +1 @@
+../../../arch/nios2/boot/dts
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/openrisc b/scripts/dtc/include-prefixes/openrisc
new file mode 120000
index 000000000..71c3bc75c
--- /dev/null
+++ b/scripts/dtc/include-prefixes/openrisc
@@ -0,0 +1 @@
+../../../arch/openrisc/boot/dts
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/powerpc b/scripts/dtc/include-prefixes/powerpc
new file mode 120000
index 000000000..7cd6ec16e
--- /dev/null
+++ b/scripts/dtc/include-prefixes/powerpc
@@ -0,0 +1 @@
+../../../arch/powerpc/boot/dts
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/riscv b/scripts/dtc/include-prefixes/riscv
new file mode 120000
index 000000000..202509418
--- /dev/null
+++ b/scripts/dtc/include-prefixes/riscv
@@ -0,0 +1 @@
+../../../arch/riscv/boot/dts
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/sh b/scripts/dtc/include-prefixes/sh
new file mode 120000
index 000000000..67d37808c
--- /dev/null
+++ b/scripts/dtc/include-prefixes/sh
@@ -0,0 +1 @@
+../../../arch/sh/boot/dts
\ No newline at end of file
diff --git a/scripts/dtc/include-prefixes/xtensa b/scripts/dtc/include-prefixes/xtensa
new file mode 120000
index 000000000..d1eaf6ec7
--- /dev/null
+++ b/scripts/dtc/include-prefixes/xtensa
@@ -0,0 +1 @@
+../../../arch/xtensa/boot/dts
\ No newline at end of file