From dd05add7b2b6004c5fa3a1f276f56d8668f86b65 Mon Sep 17 00:00:00 2001 From: Paulo Alcantara Date: Sat, 26 Sep 2026 19:20:30 -0300 Subject: netfs: zero the tail of a short DIO/unbuffered read 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 Reviewed-by: Namjae Jeon Signed-off-by: Paulo Alcantara Cc: Christian Brauner Cc: Matthew Wilcox Cc: Ronnie Sahlberg Cc: Shyam Prasad N Cc: Tom Talpey Cc: Bharath SM Cc: stable@vger.kernel.org --- drivers/vhost/Kconfig | 116 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 116 insertions(+) create mode 100644 drivers/vhost/Kconfig (limited to 'drivers/vhost/Kconfig') diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig new file mode 100644 index 000000000..bc0f38574 --- /dev/null +++ b/drivers/vhost/Kconfig @@ -0,0 +1,116 @@ +# SPDX-License-Identifier: GPL-2.0-only +config VHOST_IOTLB + tristate + help + Generic IOTLB implementation for vhost and vringh. + This option is selected by any driver which needs to support + an IOMMU in software. + +config VHOST_RING + tristate + select VHOST_IOTLB + help + This option is selected by any driver which needs to access + the host side of a virtio ring. + +config VHOST_TASK + bool + default n + +config VHOST + tristate + select VHOST_IOTLB + select VHOST_TASK + help + This option is selected by any driver which needs to access + the core of vhost. + +menuconfig VHOST_MENU + bool "VHOST drivers" + default y + +if VHOST_MENU + +config VHOST_NET + tristate "Host kernel accelerator for virtio net" + depends on NET && EVENTFD && (TUN || !TUN) && (TAP || !TAP) + select VHOST + help + This kernel module can be loaded in host kernel to accelerate + guest networking with virtio_net. Not to be confused with virtio_net + module itself which needs to be loaded in guest kernel. + + To compile this driver as a module, choose M here: the module will + be called vhost_net. + +config VHOST_SCSI + tristate "VHOST_SCSI TCM fabric driver" + depends on TARGET_CORE && EVENTFD + select VHOST + select SG_POOL + default n + help + Say M here to enable the vhost_scsi TCM fabric module + for use with virtio-scsi guests + +config VHOST_VSOCK + tristate "vhost virtio-vsock driver" + depends on VSOCKETS && EVENTFD + select VHOST + select VIRTIO_VSOCKETS_COMMON + default n + help + This kernel module can be loaded in the host kernel to provide AF_VSOCK + sockets for communicating with guests. The guests must have the + virtio_transport.ko driver loaded to use the virtio-vsock device. + + To compile this driver as a module, choose M here: the module will be called + vhost_vsock. + +config VHOST_VDPA + tristate "Vhost driver for vDPA-based backend" + depends on EVENTFD + select VHOST + select IRQ_BYPASS_MANAGER + depends on VDPA + help + This kernel module can be loaded in host kernel to accelerate + guest virtio devices with the vDPA-based backends. + + To compile this driver as a module, choose M here: the module + will be called vhost_vdpa. + +config VHOST_CROSS_ENDIAN_LEGACY + bool "Cross-endian support for vhost" + default n + help + This option allows vhost to support guests with a different byte + ordering from host while using legacy virtio. + + Userspace programs can control the feature using the + VHOST_SET_VRING_ENDIAN and VHOST_GET_VRING_ENDIAN ioctls. + + This is only useful on a few platforms (ppc64 and arm64). Since it + adds some overhead, it is disabled by default. + + If unsure, say "N". + +config VHOST_ENABLE_FORK_OWNER_CONTROL + bool "Enable VHOST_ENABLE_FORK_OWNER_CONTROL" + default y + help + This option enables two IOCTLs: VHOST_SET_FORK_FROM_OWNER and + VHOST_GET_FORK_FROM_OWNER. These allow userspace applications + to modify the vhost worker mode for vhost devices. + + Also expose module parameter 'fork_from_owner_default' to allow users + to configure the default mode for vhost workers. + + By default, `VHOST_ENABLE_FORK_OWNER_CONTROL` is set to `y`, + users can change the worker thread mode as needed. + If this config is disabled (n),the related IOCTLs and parameters will + be unavailable. + + If unsure, say "Y". + +endif -- cgit v1.3.1