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, 84 insertions, 0 deletions

diff --git a/drivers/rpmsg/Kconfig b/drivers/rpmsg/Kconfig
new file mode 100644
index 000000000..d3795860f
--- /dev/null
+++ b/drivers/rpmsg/Kconfig
@@ -0,0 +1,84 @@
+# SPDX-License-Identifier: GPL-2.0
+
+menu "Rpmsg drivers"
+
+# RPMSG always gets selected by whoever wants it
+config RPMSG
+	tristate
+
+config RPMSG_CHAR
+	tristate "RPMSG device interface"
+	depends on RPMSG
+	depends on NET
+	help
+	  Say Y here to export rpmsg endpoints as device files, usually found
+	  in /dev. They make it possible for user-space programs to send and
+	  receive rpmsg packets.
+
+config RPMSG_CTRL
+	tristate "RPMSG control interface"
+	depends on RPMSG && ( RPMSG_CHAR || RPMSG_CHAR=n )
+	help
+	  Say Y here to enable the support of the /dev/rpmsg_ctrlX API. This API
+	  allows user-space programs to create endpoints with specific service name,
+	  source and destination addresses.
+
+config RPMSG_NS
+	tristate "RPMSG name service announcement"
+	depends on RPMSG
+	help
+	  Say Y here to enable the support of the name service announcement
+	  channel that probes the associated RPMsg device on remote endpoint
+	  service announcement.
+
+config RPMSG_MTK_SCP
+	tristate "MediaTek SCP"
+	depends on MTK_SCP
+	select RPMSG
+	help
+	  Say y here to enable support providing communication channels to
+	  remote processors in MediaTek platforms.
+	  This use IPI and IPC to communicate with remote processors.
+
+config RPMSG_QCOM_GLINK
+	tristate
+	select RPMSG
+
+config RPMSG_QCOM_GLINK_RPM
+	tristate "Qualcomm RPM Glink driver"
+	select RPMSG_QCOM_GLINK
+	depends on HAS_IOMEM
+	depends on MAILBOX
+	help
+	  Say y here to enable support for the GLINK RPM communication driver,
+	  which serves as a channel for communication with the RPM in GLINK
+	  enabled systems.
+
+config RPMSG_QCOM_GLINK_SMEM
+	tristate "Qualcomm SMEM Glink driver"
+	select RPMSG_QCOM_GLINK
+	depends on MAILBOX
+	depends on QCOM_SMEM
+	help
+	  Say y here to enable support for the GLINK SMEM communication driver,
+	  which provides support for using the GLINK communication protocol
+	  over SMEM.
+
+config RPMSG_QCOM_SMD
+	tristate "Qualcomm Shared Memory Driver (SMD)"
+	depends on MAILBOX
+	depends on QCOM_SMEM
+	select RPMSG
+	help
+	  Say y here to enable support for the Qualcomm Shared Memory Driver
+	  providing communication channels to remote processors in Qualcomm
+	  platforms.
+
+config RPMSG_VIRTIO
+	tristate "Virtio RPMSG bus driver"
+	depends on HAS_DMA
+	select RPMSG
+	select RPMSG_NS
+	select VIRTIO
+
+endmenu