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, 22 insertions, 0 deletions

diff --git a/drivers/firewire/Makefile b/drivers/firewire/Makefile
new file mode 100644
index 000000000..1ff550e93
--- /dev/null
+++ b/drivers/firewire/Makefile
@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the Linux IEEE 1394 implementation
+#
+
+firewire-core-y += core-trace.o core-card.o core-cdev.o core-device.o \
+                   core-iso.o core-topology.o core-transaction.o
+firewire-ohci-y += ohci.o
+firewire-sbp2-y += sbp2.o
+firewire-net-y  += net.o
+
+obj-$(CONFIG_FIREWIRE)      += firewire-core.o
+obj-$(CONFIG_FIREWIRE_OHCI) += firewire-ohci.o
+obj-$(CONFIG_FIREWIRE_SBP2) += firewire-sbp2.o
+obj-$(CONFIG_FIREWIRE_NET)  += firewire-net.o
+obj-$(CONFIG_FIREWIRE_NOSY) += nosy.o
+obj-$(CONFIG_PROVIDE_OHCI1394_DMA_INIT) += init_ohci1394_dma.o
+
+obj-$(CONFIG_FIREWIRE_KUNIT_UAPI_TEST) += uapi-test.o
+obj-$(CONFIG_FIREWIRE_KUNIT_PACKET_SERDES_TEST) += packet-serdes-test.o
+obj-$(CONFIG_FIREWIRE_KUNIT_SELF_ID_SEQUENCE_HELPER_TEST) += self-id-sequence-helper-test.o
+obj-$(CONFIG_FIREWIRE_KUNIT_OHCI_SERDES_TEST) += ohci-serdes-test.o