Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted

Pull networking updates from Jakub Kicinski:
 "Core:

   - Add dedicated kmem_cache for typical/small skb->head, avoid having
     to access struct page at kfree time, and improve memory use.

   - Introduce sysctl to set default RPS configuration for new netdevs.

   - Define Netlink protocol specification format which can be used to
     describe messages used by each family and auto-generate parsers.
     Add tools for generating kernel data structures and uAPI headers.

   - Expose all net/core sysctls inside netns.

   - Remove 4s sleep in netpoll if carrier is instantly detected on
     boot.

   - Add configurable limit of MDB entries per port, and port-vlan.

   - Continue populating drop reasons throughout the stack.

   - Retire a handful of legacy Qdiscs and classifiers.

  Protocols:

   - Support IPv4 big TCP (TSO frames larger than 64kB).

   - Add IP_LOCAL_PORT_RANGE socket option, to control local port range
     on socket by socket basis.

   - Track and report in procfs number of MPTCP sockets used.

   - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
     manager.

   - IPv6: don't check net.ipv6.route.max_size and rely on garbage
     collection to free memory (similarly to IPv4).

   - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).

   - ICMP: add per-rate limit counters.

   - Add support for user scanning requests in ieee802154.

   - Remove static WEP support.

   - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
     reporting.

   - WiFi 7 EHT channel puncturing support (client & AP).

  BPF:

   - Add a rbtree data structure following the "next-gen data structure"
     precedent set by recently added linked list, that is, by using
     kfunc + kptr instead of adding a new BPF map type.

   - Expose XDP hints via kfuncs with initial support for RX hash and
     timestamp metadata.

   - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
     better support decap on GRE tunnel devices not operating in collect
     metadata.

   - Improve x86 JIT's codegen for PROBE_MEM runtime error checks.

   - Remove the need for trace_printk_lock for bpf_trace_printk and
     bpf_trace_vprintk helpers.

   - Extend libbpf's bpf_tracing.h support for tracing arguments of
     kprobes/uprobes and syscall as a special case.

   - Significantly reduce the search time for module symbols by
     livepatch and BPF.

   - Enable cpumasks to be used as kptrs, which is useful for tracing
     programs tracking which tasks end up running on which CPUs in
     different time intervals.

   - Add support for BPF trampoline on s390x and riscv64.

   - Add capability to export the XDP features supported by the NIC.

   - Add __bpf_kfunc tag for marking kernel functions as kfuncs.

   - Add cgroup.memory=nobpf kernel parameter option to disable BPF
     memory accounting for container environments.

  Netfilter:

   - Remove the CLUSTERIP target. It has been marked as obsolete for
     years, and we still have WARN splats wrt races of the out-of-band
     /proc interface installed by this target.

   - Add 'destroy' commands to nf_tables. They are identical to the
     existing 'delete' commands, but do not return an error if the
     referenced object (set, chain, rule...) did not exist.

  Driver API:

   - Improve cpumask_local_spread() locality to help NICs set the right
     IRQ affinity on AMD platforms.

   - Separate C22 and C45 MDIO bus transactions more clearly.

   - Introduce new DCB table to control DSCP rewrite on egress.

   - Support configuration of Physical Layer Collision Avoidance (PLCA)
     Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
     shared medium Ethernet.

   - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
     preemption of low priority frames by high priority frames.

   - Add support for controlling MACSec offload using netlink SET.

   - Rework devlink instance refcounts to allow registration and
     de-registration under the instance lock. Split the code into
     multiple files, drop some of the unnecessarily granular locks and
     factor out common parts of netlink operation handling.

   - Add TX frame aggregation parameters (for USB drivers).

   - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
     messages with notifications for debug.

   - Allow offloading of UDP NEW connections via act_ct.

   - Add support for per action HW stats in TC.

   - Support hardware miss to TC action (continue processing in SW from
     a specific point in the action chain).

   - Warn if old Wireless Extension user space interface is used with
     modern cfg80211/mac80211 drivers. Do not support Wireless
     Extensions for Wi-Fi 7 devices at all. Everyone should switch to
     using nl80211 interface instead.

   - Improve the CAN bit timing configuration. Use extack to return
     error messages directly to user space, update the SJW handling,
     including the definition of a new default value that will benefit
     CAN-FD controllers, by increasing their oscillator tolerance.

  New hardware / drivers:

   - Ethernet:
      - nVidia BlueField-3 support (control traffic driver)
      - Ethernet support for imx93 SoCs
      - Motorcomm yt8531 gigabit Ethernet PHY
      - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
      - Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
      - Amlogic gxl MDIO mux

   - WiFi:
      - RealTek RTL8188EU (rtl8xxxu)
      - Qualcomm Wi-Fi 7 devices (ath12k)

   - CAN:
      - Renesas R-Car V4H

  Drivers:

   - Bluetooth:
      - Set Per Platform Antenna Gain (PPAG) for Intel controllers.

   - Ethernet NICs:
      - Intel (1G, igc):
         - support TSN / Qbv / packet scheduling features of i226 model
      - Intel (100G, ice):
         - use GNSS subsystem instead of TTY
         - multi-buffer XDP support
         - extend support for GPIO pins to E823 devices
      - nVidia/Mellanox:
         - update the shared buffer configuration on PFC commands
         - implement PTP adjphase function for HW offset control
         - TC support for Geneve and GRE with VF tunnel offload
         - more efficient crypto key management method
         - multi-port eswitch support
      - Netronome/Corigine:
         - add DCB IEEE support
         - support IPsec offloading for NFP3800
      - Freescale/NXP (enetc):
         - support XDP_REDIRECT for XDP non-linear buffers
         - improve reconfig, avoid link flap and waiting for idle
         - support MAC Merge layer
      - Other NICs:
         - sfc/ef100: add basic devlink support for ef100
         - ionic: rx_push mode operation (writing descriptors via MMIO)
         - bnxt: use the auxiliary bus abstraction for RDMA
         - r8169: disable ASPM and reset bus in case of tx timeout
         - cpsw: support QSGMII mode for J721e CPSW9G
         - cpts: support pulse-per-second output
         - ngbe: add an mdio bus driver
         - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
         - r8152: handle devices with FW with NCM support
         - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
         - virtio-net: support multi buffer XDP
         - virtio/vsock: replace virtio_vsock_pkt with sk_buff
         - tsnep: XDP support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add support for latency TLV (in FW control messages)
      - Microchip (sparx5):
         - separate explicit and implicit traffic forwarding rules, make
           the implicit rules always active
         - add support for egress DSCP rewrite
         - IS0 VCAP support (Ingress Classification)
         - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
           etc.)
         - ES2 VCAP support (Egress Access Control)
         - support for Per-Stream Filtering and Policing (802.1Q,
           8.6.5.1)

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - add MAB (port auth) offload support
         - enable PTP receive for mv88e6390
      - NXP (ocelot):
         - support MAC Merge layer
         - support for the the vsc7512 internal copper phys
      - Microchip:
         - lan9303: convert to PHYLINK
         - lan966x: support TC flower filter statistics
         - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
         - lan937x: support Credit Based Shaper configuration
         - ksz9477: support Energy Efficient Ethernet
      - other:
         - qca8k: convert to regmap read/write API, use bulk operations
         - rswitch: Improve TX timestamp accuracy

   - Intel WiFi (iwlwifi):
      - EHT (Wi-Fi 7) rate reporting
      - STEP equalizer support: transfer some STEP (connection to radio
        on platforms with integrated wifi) related parameters from the
        BIOS to the firmware.

   - Qualcomm 802.11ax WiFi (ath11k):
      - IPQ5018 support
      - Fine Timing Measurement (FTM) responder role support
      - channel 177 support

   - MediaTek WiFi (mt76):
      - per-PHY LED support
      - mt7996: EHT (Wi-Fi 7) support
      - Wireless Ethernet Dispatch (WED) reset support
      - switch to using page pool allocator

   - RealTek WiFi (rtw89):
      - support new version of Bluetooth co-existance

   - Mobile:
      - rmnet: support TX aggregation"

* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
  page_pool: add a comment explaining the fragment counter usage
  net: ethtool: fix __ethtool_dev_mm_supported() implementation
  ethtool: pse-pd: Fix double word in comments
  xsk: add linux/vmalloc.h to xsk.c
  sefltests: netdevsim: wait for devlink instance after netns removal
  selftest: fib_tests: Always cleanup before exit
  net/mlx5e: Align IPsec ASO result memory to be as required by hardware
  net/mlx5e: TC, Set CT miss to the specific ct action instance
  net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
  net/mlx5: Refactor tc miss handling to a single function
  net/mlx5: Kconfig: Make tc offload depend on tc skb extension
  net/sched: flower: Support hardware miss to tc action
  net/sched: flower: Move filter handle initialization earlier
  net/sched: cls_api: Support hardware miss to tc action
  net/sched: Rename user cookie and act cookie
  sfc: fix builds without CONFIG_RTC_LIB
  sfc: clean up some inconsistent indentings
  net/mlx4_en: Introduce flexible array to silence overflow warning
  net: lan966x: Fix possible deadlock inside PTP
  net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
  ...

1 files changed, 674 insertions, 0 deletions

diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c
new file mode 100644
index 000000000..175a25fca
--- /dev/null
+++ b/fs/cachefiles/io.c
@@ -0,0 +1,674 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* kiocb-using read/write
+ *
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/mount.h>
+#include <linux/slab.h>
+#include <linux/file.h>
+#include <linux/uio.h>
+#include <linux/falloc.h>
+#include <linux/sched/mm.h>
+#include <trace/events/fscache.h>
+#include "internal.h"
+
+struct cachefiles_kiocb {
+	struct kiocb		iocb;
+	refcount_t		ki_refcnt;
+	loff_t			start;
+	union {
+		size_t		skipped;
+		size_t		len;
+	};
+	struct cachefiles_object *object;
+	netfs_io_terminated_t	term_func;
+	void			*term_func_priv;
+	bool			was_async;
+	unsigned int		inval_counter;	/* Copy of cookie->inval_counter */
+	u64			b_writing;
+};
+
+static inline void cachefiles_put_kiocb(struct cachefiles_kiocb *ki)
+{
+	if (refcount_dec_and_test(&ki->ki_refcnt)) {
+		cachefiles_put_object(ki->object, cachefiles_obj_put_ioreq);
+		fput(ki->iocb.ki_filp);
+		kfree(ki);
+	}
+}
+
+/*
+ * Handle completion of a read from the cache.
+ */
+static void cachefiles_read_complete(struct kiocb *iocb, long ret)
+{
+	struct cachefiles_kiocb *ki = container_of(iocb, struct cachefiles_kiocb, iocb);
+	struct inode *inode = file_inode(ki->iocb.ki_filp);
+
+	_enter("%ld", ret);
+
+	if (ret < 0)
+		trace_cachefiles_io_error(ki->object, inode, ret,
+					  cachefiles_trace_read_error);
+
+	if (ki->term_func) {
+		if (ret >= 0) {
+			if (ki->object->cookie->inval_counter == ki->inval_counter)
+				ki->skipped += ret;
+			else
+				ret = -ESTALE;
+		}
+
+		ki->term_func(ki->term_func_priv, ret, ki->was_async);
+	}
+
+	cachefiles_put_kiocb(ki);
+}
+
+/*
+ * Initiate a read from the cache.
+ */
+static int cachefiles_read(struct netfs_cache_resources *cres,
+			   loff_t start_pos,
+			   struct iov_iter *iter,
+			   enum netfs_read_from_hole read_hole,
+			   netfs_io_terminated_t term_func,
+			   void *term_func_priv)
+{
+	struct cachefiles_object *object;
+	struct cachefiles_kiocb *ki;
+	struct file *file;
+	unsigned int old_nofs;
+	ssize_t ret = -ENOBUFS;
+	size_t len = iov_iter_count(iter), skipped = 0;
+
+	if (!fscache_wait_for_operation(cres, FSCACHE_WANT_READ))
+		goto presubmission_error;
+
+	fscache_count_read();
+	object = cachefiles_cres_object(cres);
+	file = cachefiles_cres_file(cres);
+
+	_enter("%pD,%li,%llx,%zx/%llx",
+	       file, file_inode(file)->i_ino, start_pos, len,
+	       i_size_read(file_inode(file)));
+
+	/* If the caller asked us to seek for data before doing the read, then
+	 * we should do that now.  If we find a gap, we fill it with zeros.
+	 */
+	if (read_hole != NETFS_READ_HOLE_IGNORE) {
+		loff_t off = start_pos, off2;
+
+		off2 = cachefiles_inject_read_error();
+		if (off2 == 0)
+			off2 = vfs_llseek(file, off, SEEK_DATA);
+		if (off2 < 0 && off2 >= (loff_t)-MAX_ERRNO && off2 != -ENXIO) {
+			skipped = 0;
+			ret = off2;
+			goto presubmission_error;
+		}
+
+		if (off2 == -ENXIO || off2 >= start_pos + len) {
+			/* The region is beyond the EOF or there's no more data
+			 * in the region, so clear the rest of the buffer and
+			 * return success.
+			 */
+			ret = -ENODATA;
+			if (read_hole == NETFS_READ_HOLE_FAIL)
+				goto presubmission_error;
+
+			iov_iter_zero(len, iter);
+			skipped = len;
+			ret = 0;
+			goto presubmission_error;
+		}
+
+		skipped = off2 - off;
+		iov_iter_zero(skipped, iter);
+	}
+
+	ret = -ENOMEM;
+	ki = kzalloc(sizeof(struct cachefiles_kiocb), GFP_KERNEL);
+	if (!ki)
+		goto presubmission_error;
+
+	refcount_set(&ki->ki_refcnt, 2);
+	ki->iocb.ki_filp	= file;
+	ki->iocb.ki_pos		= start_pos + skipped;
+	ki->iocb.ki_flags	= IOCB_DIRECT;
+	ki->iocb.ki_ioprio	= get_current_ioprio();
+	ki->skipped		= skipped;
+	ki->object		= object;
+	ki->inval_counter	= cres->inval_counter;
+	ki->term_func		= term_func;
+	ki->term_func_priv	= term_func_priv;
+	ki->was_async		= true;
+
+	if (ki->term_func)
+		ki->iocb.ki_complete = cachefiles_read_complete;
+
+	get_file(ki->iocb.ki_filp);
+	cachefiles_grab_object(object, cachefiles_obj_get_ioreq);
+
+	trace_cachefiles_read(object, file_inode(file), ki->iocb.ki_pos, len - skipped);
+	old_nofs = memalloc_nofs_save();
+	ret = cachefiles_inject_read_error();
+	if (ret == 0)
+		ret = vfs_iocb_iter_read(file, &ki->iocb, iter);
+	memalloc_nofs_restore(old_nofs);
+	switch (ret) {
+	case -EIOCBQUEUED:
+		goto in_progress;
+
+	case -ERESTARTSYS:
+	case -ERESTARTNOINTR:
+	case -ERESTARTNOHAND:
+	case -ERESTART_RESTARTBLOCK:
+		/* There's no easy way to restart the syscall since other AIO's
+		 * may be already running. Just fail this IO with EINTR.
+		 */
+		ret = -EINTR;
+		fallthrough;
+	default:
+		ki->was_async = false;
+		cachefiles_read_complete(&ki->iocb, ret);
+		if (ret > 0)
+			ret = 0;
+		break;
+	}
+
+in_progress:
+	cachefiles_put_kiocb(ki);
+	_leave(" = %zd", ret);
+	return ret;
+
+presubmission_error:
+	if (term_func)
+		term_func(term_func_priv, ret < 0 ? ret : skipped, false);
+	return ret;
+}
+
+/*
+ * Query the occupancy of the cache in a region, returning where the next chunk
+ * of data starts and how long it is.
+ */
+static int cachefiles_query_occupancy(struct netfs_cache_resources *cres,
+				      loff_t start, size_t len, size_t granularity,
+				      loff_t *_data_start, size_t *_data_len)
+{
+	struct cachefiles_object *object;
+	struct file *file;
+	loff_t off, off2;
+
+	*_data_start = -1;
+	*_data_len = 0;
+
+	if (!fscache_wait_for_operation(cres, FSCACHE_WANT_READ))
+		return -ENOBUFS;
+
+	object = cachefiles_cres_object(cres);
+	file = cachefiles_cres_file(cres);
+	granularity = max_t(size_t, object->volume->cache->bsize, granularity);
+
+	_enter("%pD,%li,%llx,%zx/%llx",
+	       file, file_inode(file)->i_ino, start, len,
+	       i_size_read(file_inode(file)));
+
+	off = cachefiles_inject_read_error();
+	if (off == 0)
+		off = vfs_llseek(file, start, SEEK_DATA);
+	if (off == -ENXIO)
+		return -ENODATA; /* Beyond EOF */
+	if (off < 0 && off >= (loff_t)-MAX_ERRNO)
+		return -ENOBUFS; /* Error. */
+	if (round_up(off, granularity) >= start + len)
+		return -ENODATA; /* No data in range */
+
+	off2 = cachefiles_inject_read_error();
+	if (off2 == 0)
+		off2 = vfs_llseek(file, off, SEEK_HOLE);
+	if (off2 == -ENXIO)
+		return -ENODATA; /* Beyond EOF */
+	if (off2 < 0 && off2 >= (loff_t)-MAX_ERRNO)
+		return -ENOBUFS; /* Error. */
+
+	/* Round away partial blocks */
+	off = round_up(off, granularity);
+	off2 = round_down(off2, granularity);
+	if (off2 <= off)
+		return -ENODATA;
+
+	*_data_start = off;
+	if (off2 > start + len)
+		*_data_len = len;
+	else
+		*_data_len = off2 - off;
+	return 0;
+}
+
+/*
+ * Handle completion of a write to the cache.
+ */
+static void cachefiles_write_complete(struct kiocb *iocb, long ret)
+{
+	struct cachefiles_kiocb *ki = container_of(iocb, struct cachefiles_kiocb, iocb);
+	struct cachefiles_object *object = ki->object;
+	struct inode *inode = file_inode(ki->iocb.ki_filp);
+
+	_enter("%ld", ret);
+
+	/* Tell lockdep we inherited freeze protection from submission thread */
+	__sb_writers_acquired(inode->i_sb, SB_FREEZE_WRITE);
+	__sb_end_write(inode->i_sb, SB_FREEZE_WRITE);
+
+	if (ret < 0)
+		trace_cachefiles_io_error(object, inode, ret,
+					  cachefiles_trace_write_error);
+
+	atomic_long_sub(ki->b_writing, &object->volume->cache->b_writing);
+	set_bit(FSCACHE_COOKIE_HAVE_DATA, &object->cookie->flags);
+	if (ki->term_func)
+		ki->term_func(ki->term_func_priv, ret, ki->was_async);
+	cachefiles_put_kiocb(ki);
+}
+
+/*
+ * Initiate a write to the cache.
+ */
+int __cachefiles_write(struct cachefiles_object *object,
+		       struct file *file,
+		       loff_t start_pos,
+		       struct iov_iter *iter,
+		       netfs_io_terminated_t term_func,
+		       void *term_func_priv)
+{
+	struct cachefiles_cache *cache;
+	struct cachefiles_kiocb *ki;
+	struct inode *inode;
+	unsigned int old_nofs;
+	ssize_t ret;
+	size_t len = iov_iter_count(iter);
+
+	fscache_count_write();
+	cache = object->volume->cache;
+
+	_enter("%pD,%li,%llx,%zx/%llx",
+	       file, file_inode(file)->i_ino, start_pos, len,
+	       i_size_read(file_inode(file)));
+
+	ki = kzalloc(sizeof(struct cachefiles_kiocb), GFP_KERNEL);
+	if (!ki) {
+		if (term_func)
+			term_func(term_func_priv, -ENOMEM, false);
+		return -ENOMEM;
+	}
+
+	refcount_set(&ki->ki_refcnt, 2);
+	ki->iocb.ki_filp	= file;
+	ki->iocb.ki_pos		= start_pos;
+	ki->iocb.ki_flags	= IOCB_DIRECT | IOCB_WRITE;
+	ki->iocb.ki_ioprio	= get_current_ioprio();
+	ki->object		= object;
+	ki->start		= start_pos;
+	ki->len			= len;
+	ki->term_func		= term_func;
+	ki->term_func_priv	= term_func_priv;
+	ki->was_async		= true;
+	ki->b_writing		= (len + (1 << cache->bshift) - 1) >> cache->bshift;
+
+	if (ki->term_func)
+		ki->iocb.ki_complete = cachefiles_write_complete;
+	atomic_long_add(ki->b_writing, &cache->b_writing);
+
+	/* Open-code file_start_write here to grab freeze protection, which
+	 * will be released by another thread in aio_complete_rw().  Fool
+	 * lockdep by telling it the lock got released so that it doesn't
+	 * complain about the held lock when we return to userspace.
+	 */
+	inode = file_inode(file);
+	__sb_start_write(inode->i_sb, SB_FREEZE_WRITE);
+	__sb_writers_release(inode->i_sb, SB_FREEZE_WRITE);
+
+	get_file(ki->iocb.ki_filp);
+	cachefiles_grab_object(object, cachefiles_obj_get_ioreq);
+
+	trace_cachefiles_write(object, inode, ki->iocb.ki_pos, len);
+	old_nofs = memalloc_nofs_save();
+	ret = cachefiles_inject_write_error();
+	if (ret == 0)
+		ret = vfs_iocb_iter_write(file, &ki->iocb, iter);
+	memalloc_nofs_restore(old_nofs);
+	switch (ret) {
+	case -EIOCBQUEUED:
+		goto in_progress;
+
+	case -ERESTARTSYS:
+	case -ERESTARTNOINTR:
+	case -ERESTARTNOHAND:
+	case -ERESTART_RESTARTBLOCK:
+		/* There's no easy way to restart the syscall since other AIO's
+		 * may be already running. Just fail this IO with EINTR.
+		 */
+		ret = -EINTR;
+		fallthrough;
+	default:
+		ki->was_async = false;
+		cachefiles_write_complete(&ki->iocb, ret);
+		if (ret > 0)
+			ret = 0;
+		break;
+	}
+
+in_progress:
+	cachefiles_put_kiocb(ki);
+	_leave(" = %zd", ret);
+	return ret;
+}
+
+static int cachefiles_write(struct netfs_cache_resources *cres,
+			    loff_t start_pos,
+			    struct iov_iter *iter,
+			    netfs_io_terminated_t term_func,
+			    void *term_func_priv)
+{
+	if (!fscache_wait_for_operation(cres, FSCACHE_WANT_WRITE)) {
+		if (term_func)
+			term_func(term_func_priv, -ENOBUFS, false);
+		return -ENOBUFS;
+	}
+
+	return __cachefiles_write(cachefiles_cres_object(cres),
+				  cachefiles_cres_file(cres),
+				  start_pos, iter,
+				  term_func, term_func_priv);
+}
+
+static inline enum netfs_io_source
+cachefiles_do_prepare_read(struct netfs_cache_resources *cres,
+			   loff_t start, size_t *_len, loff_t i_size,
+			   unsigned long *_flags, ino_t netfs_ino)
+{
+	enum cachefiles_prepare_read_trace why;
+	struct cachefiles_object *object = NULL;
+	struct cachefiles_cache *cache;
+	struct fscache_cookie *cookie = fscache_cres_cookie(cres);
+	const struct cred *saved_cred;
+	struct file *file = cachefiles_cres_file(cres);
+	enum netfs_io_source ret = NETFS_DOWNLOAD_FROM_SERVER;
+	size_t len = *_len;
+	loff_t off, to;
+	ino_t ino = file ? file_inode(file)->i_ino : 0;
+	int rc;
+
+	_enter("%zx @%llx/%llx", len, start, i_size);
+
+	if (start >= i_size) {
+		ret = NETFS_FILL_WITH_ZEROES;
+		why = cachefiles_trace_read_after_eof;
+		goto out_no_object;
+	}
+
+	if (test_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags)) {
+		__set_bit(NETFS_SREQ_COPY_TO_CACHE, _flags);
+		why = cachefiles_trace_read_no_data;
+		if (!test_bit(NETFS_SREQ_ONDEMAND, _flags))
+			goto out_no_object;
+	}
+
+	/* The object and the file may be being created in the background. */
+	if (!file) {
+		why = cachefiles_trace_read_no_file;
+		if (!fscache_wait_for_operation(cres, FSCACHE_WANT_READ))
+			goto out_no_object;
+		file = cachefiles_cres_file(cres);
+		if (!file)
+			goto out_no_object;
+		ino = file_inode(file)->i_ino;
+	}
+
+	object = cachefiles_cres_object(cres);
+	cache = object->volume->cache;
+	cachefiles_begin_secure(cache, &saved_cred);
+retry:
+	off = cachefiles_inject_read_error();
+	if (off == 0)
+		off = vfs_llseek(file, start, SEEK_DATA);
+	if (off < 0 && off >= (loff_t)-MAX_ERRNO) {
+		if (off == (loff_t)-ENXIO) {
+			why = cachefiles_trace_read_seek_nxio;
+			goto download_and_store;
+		}
+		trace_cachefiles_io_error(object, file_inode(file), off,
+					  cachefiles_trace_seek_error);
+		why = cachefiles_trace_read_seek_error;
+		goto out;
+	}
+
+	if (off >= start + len) {
+		why = cachefiles_trace_read_found_hole;
+		goto download_and_store;
+	}
+
+	if (off > start) {
+		off = round_up(off, cache->bsize);
+		len = off - start;
+		*_len = len;
+		why = cachefiles_trace_read_found_part;
+		goto download_and_store;
+	}
+
+	to = cachefiles_inject_read_error();
+	if (to == 0)
+		to = vfs_llseek(file, start, SEEK_HOLE);
+	if (to < 0 && to >= (loff_t)-MAX_ERRNO) {
+		trace_cachefiles_io_error(object, file_inode(file), to,
+					  cachefiles_trace_seek_error);
+		why = cachefiles_trace_read_seek_error;
+		goto out;
+	}
+
+	if (to < start + len) {
+		if (start + len >= i_size)
+			to = round_up(to, cache->bsize);
+		else
+			to = round_down(to, cache->bsize);
+		len = to - start;
+		*_len = len;
+	}
+
+	why = cachefiles_trace_read_have_data;
+	ret = NETFS_READ_FROM_CACHE;
+	goto out;
+
+download_and_store:
+	__set_bit(NETFS_SREQ_COPY_TO_CACHE, _flags);
+	if (test_bit(NETFS_SREQ_ONDEMAND, _flags)) {
+		rc = cachefiles_ondemand_read(object, start, len);
+		if (!rc) {
+			__clear_bit(NETFS_SREQ_ONDEMAND, _flags);
+			goto retry;
+		}
+		ret = NETFS_INVALID_READ;
+	}
+out:
+	cachefiles_end_secure(cache, saved_cred);
+out_no_object:
+	trace_cachefiles_prep_read(object, start, len, *_flags, ret, why, ino, netfs_ino);
+	return ret;
+}
+
+/*
+ * Prepare a read operation, shortening it to a cached/uncached
+ * boundary as appropriate.
+ */
+static enum netfs_io_source cachefiles_prepare_read(struct netfs_io_subrequest *subreq,
+						    loff_t i_size)
+{
+	return cachefiles_do_prepare_read(&subreq->rreq->cache_resources,
+					  subreq->start, &subreq->len, i_size,
+					  &subreq->flags, subreq->rreq->inode->i_ino);
+}
+
+/*
+ * Prepare an on-demand read operation, shortening it to a cached/uncached
+ * boundary as appropriate.
+ */
+static enum netfs_io_source
+cachefiles_prepare_ondemand_read(struct netfs_cache_resources *cres,
+				 loff_t start, size_t *_len, loff_t i_size,
+				 unsigned long *_flags, ino_t ino)
+{
+	return cachefiles_do_prepare_read(cres, start, _len, i_size, _flags, ino);
+}
+
+/*
+ * Prepare for a write to occur.
+ */
+int __cachefiles_prepare_write(struct cachefiles_object *object,
+			       struct file *file,
+			       loff_t *_start, size_t *_len,
+			       bool no_space_allocated_yet)
+{
+	struct cachefiles_cache *cache = object->volume->cache;
+	loff_t start = *_start, pos;
+	size_t len = *_len, down;
+	int ret;
+
+	/* Round to DIO size */
+	down = start - round_down(start, PAGE_SIZE);
+	*_start = start - down;
+	*_len = round_up(down + len, PAGE_SIZE);
+
+	/* We need to work out whether there's sufficient disk space to perform
+	 * the write - but we can skip that check if we have space already
+	 * allocated.
+	 */
+	if (no_space_allocated_yet)
+		goto check_space;
+
+	pos = cachefiles_inject_read_error();
+	if (pos == 0)
+		pos = vfs_llseek(file, *_start, SEEK_DATA);
+	if (pos < 0 && pos >= (loff_t)-MAX_ERRNO) {
+		if (pos == -ENXIO)
+			goto check_space; /* Unallocated tail */
+		trace_cachefiles_io_error(object, file_inode(file), pos,
+					  cachefiles_trace_seek_error);
+		return pos;
+	}
+	if ((u64)pos >= (u64)*_start + *_len)
+		goto check_space; /* Unallocated region */
+
+	/* We have a block that's at least partially filled - if we're low on
+	 * space, we need to see if it's fully allocated.  If it's not, we may
+	 * want to cull it.
+	 */
+	if (cachefiles_has_space(cache, 0, *_len / PAGE_SIZE,
+				 cachefiles_has_space_check) == 0)
+		return 0; /* Enough space to simply overwrite the whole block */
+
+	pos = cachefiles_inject_read_error();
+	if (pos == 0)
+		pos = vfs_llseek(file, *_start, SEEK_HOLE);
+	if (pos < 0 && pos >= (loff_t)-MAX_ERRNO) {
+		trace_cachefiles_io_error(object, file_inode(file), pos,
+					  cachefiles_trace_seek_error);
+		return pos;
+	}
+	if ((u64)pos >= (u64)*_start + *_len)
+		return 0; /* Fully allocated */
+
+	/* Partially allocated, but insufficient space: cull. */
+	fscache_count_no_write_space();
+	ret = cachefiles_inject_remove_error();
+	if (ret == 0)
+		ret = vfs_fallocate(file, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
+				    *_start, *_len);
+	if (ret < 0) {
+		trace_cachefiles_io_error(object, file_inode(file), ret,
+					  cachefiles_trace_fallocate_error);
+		cachefiles_io_error_obj(object,
+					"CacheFiles: fallocate failed (%d)\n", ret);
+		ret = -EIO;
+	}
+
+	return ret;
+
+check_space:
+	return cachefiles_has_space(cache, 0, *_len / PAGE_SIZE,
+				    cachefiles_has_space_for_write);
+}
+
+static int cachefiles_prepare_write(struct netfs_cache_resources *cres,
+				    loff_t *_start, size_t *_len, loff_t i_size,
+				    bool no_space_allocated_yet)
+{
+	struct cachefiles_object *object = cachefiles_cres_object(cres);
+	struct cachefiles_cache *cache = object->volume->cache;
+	const struct cred *saved_cred;
+	int ret;
+
+	if (!cachefiles_cres_file(cres)) {
+		if (!fscache_wait_for_operation(cres, FSCACHE_WANT_WRITE))
+			return -ENOBUFS;
+		if (!cachefiles_cres_file(cres))
+			return -ENOBUFS;
+	}
+
+	cachefiles_begin_secure(cache, &saved_cred);
+	ret = __cachefiles_prepare_write(object, cachefiles_cres_file(cres),
+					 _start, _len,
+					 no_space_allocated_yet);
+	cachefiles_end_secure(cache, saved_cred);
+	return ret;
+}
+
+/*
+ * Clean up an operation.
+ */
+static void cachefiles_end_operation(struct netfs_cache_resources *cres)
+{
+	struct file *file = cachefiles_cres_file(cres);
+
+	if (file)
+		fput(file);
+	fscache_end_cookie_access(fscache_cres_cookie(cres), fscache_access_io_end);
+}
+
+static const struct netfs_cache_ops cachefiles_netfs_cache_ops = {
+	.end_operation		= cachefiles_end_operation,
+	.read			= cachefiles_read,
+	.write			= cachefiles_write,
+	.prepare_read		= cachefiles_prepare_read,
+	.prepare_write		= cachefiles_prepare_write,
+	.prepare_ondemand_read	= cachefiles_prepare_ondemand_read,
+	.query_occupancy	= cachefiles_query_occupancy,
+};
+
+/*
+ * Open the cache file when beginning a cache operation.
+ */
+bool cachefiles_begin_operation(struct netfs_cache_resources *cres,
+				enum fscache_want_state want_state)
+{
+	struct cachefiles_object *object = cachefiles_cres_object(cres);
+
+	if (!cachefiles_cres_file(cres)) {
+		cres->ops = &cachefiles_netfs_cache_ops;
+		if (object->file) {
+			spin_lock(&object->lock);
+			if (!cres->cache_priv2 && object->file)
+				cres->cache_priv2 = get_file(object->file);
+			spin_unlock(&object->lock);
+		}
+	}
+
+	if (!cachefiles_cres_file(cres) && want_state != FSCACHE_WANT_PARAMS) {
+		pr_err("failed to get cres->file\n");
+		return false;
+	}
+
+	return true;
+}