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, 447 insertions, 0 deletions

diff --git a/fs/d_path.c b/fs/d_path.c
new file mode 100644
index 000000000..56a6ee4c6
--- /dev/null
+++ b/fs/d_path.c
@@ -0,0 +1,447 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/syscalls.h>
+#include <linux/export.h>
+#include <linux/uaccess.h>
+#include <linux/fs_struct.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/prefetch.h>
+#include "mount.h"
+
+struct prepend_buffer {
+	char *buf;
+	int len;
+};
+#define DECLARE_BUFFER(__name, __buf, __len) \
+	struct prepend_buffer __name = {.buf = __buf + __len, .len = __len}
+
+static char *extract_string(struct prepend_buffer *p)
+{
+	if (likely(p->len >= 0))
+		return p->buf;
+	return ERR_PTR(-ENAMETOOLONG);
+}
+
+static bool prepend_char(struct prepend_buffer *p, unsigned char c)
+{
+	if (likely(p->len > 0)) {
+		p->len--;
+		*--p->buf = c;
+		return true;
+	}
+	p->len = -1;
+	return false;
+}
+
+/*
+ * The source of the prepend data can be an optimistic load
+ * of a dentry name and length. And because we don't hold any
+ * locks, the length and the pointer to the name may not be
+ * in sync if a concurrent rename happens, and the kernel
+ * copy might fault as a result.
+ *
+ * The end result will correct itself when we check the
+ * rename sequence count, but we need to be able to handle
+ * the fault gracefully.
+ */
+static bool prepend_copy(void *dst, const void *src, int len)
+{
+	if (unlikely(copy_from_kernel_nofault(dst, src, len))) {
+		memset(dst, 'x', len);
+		return false;
+	}
+	return true;
+}
+
+static bool prepend(struct prepend_buffer *p, const char *str, int namelen)
+{
+	// Already overflowed?
+	if (p->len < 0)
+		return false;
+
+	// Will overflow?
+	if (p->len < namelen) {
+		// Fill as much as possible from the end of the name
+		str += namelen - p->len;
+		p->buf -= p->len;
+		prepend_copy(p->buf, str, p->len);
+		p->len = -1;
+		return false;
+	}
+
+	// Fits fully
+	p->len -= namelen;
+	p->buf -= namelen;
+	return prepend_copy(p->buf, str, namelen);
+}
+
+/**
+ * prepend_name - prepend a pathname in front of current buffer pointer
+ * @p: prepend buffer which contains buffer pointer and allocated length
+ * @name: name string and length qstr structure
+ *
+ * With RCU path tracing, it may race with d_move(). Use READ_ONCE() to
+ * make sure that either the old or the new name pointer and length are
+ * fetched. However, there may be mismatch between length and pointer.
+ * But since the length cannot be trusted, we need to copy the name very
+ * carefully when doing the prepend_copy(). It also prepends "/" at
+ * the beginning of the name. The sequence number check at the caller will
+ * retry it again when a d_move() does happen. So any garbage in the buffer
+ * due to mismatched pointer and length will be discarded.
+ *
+ * Load acquire is needed to make sure that we see the new name data even
+ * if we might get the length wrong.
+ */
+static bool prepend_name(struct prepend_buffer *p, const struct qstr *name)
+{
+	const char *dname = smp_load_acquire(&name->name); /* ^^^ */
+	u32 dlen = READ_ONCE(name->len);
+
+	return prepend(p, dname, dlen) && prepend_char(p, '/');
+}
+
+static int __prepend_path(const struct dentry *dentry, const struct mount *mnt,
+			  const struct path *root, struct prepend_buffer *p)
+{
+	while (dentry != root->dentry || &mnt->mnt != root->mnt) {
+		const struct dentry *parent = READ_ONCE(dentry->d_parent);
+
+		if (dentry == mnt->mnt.mnt_root) {
+			struct mount *m = READ_ONCE(mnt->mnt_parent);
+			struct mnt_namespace *mnt_ns;
+
+			if (likely(mnt != m)) {
+				dentry = READ_ONCE(mnt->mnt_mountpoint);
+				mnt = m;
+				continue;
+			}
+			/* Global root */
+			mnt_ns = READ_ONCE(mnt->mnt_ns);
+			/* open-coded is_mounted() to use local mnt_ns */
+			if (!IS_ERR_OR_NULL(mnt_ns) && !is_anon_ns(mnt_ns))
+				return 1;	// absolute root
+			else
+				return 2;	// detached or not attached yet
+		}
+
+		if (unlikely(dentry == parent))
+			/* Escaped? */
+			return 3;
+
+		prefetch(parent);
+		if (!prepend_name(p, &dentry->d_name))
+			break;
+		dentry = parent;
+	}
+	return 0;
+}
+
+/**
+ * prepend_path - Prepend path string to a buffer
+ * @path: the dentry/vfsmount to report
+ * @root: root vfsmnt/dentry
+ * @p: prepend buffer which contains buffer pointer and allocated length
+ *
+ * The function will first try to write out the pathname without taking any
+ * lock other than the RCU read lock to make sure that dentries won't go away.
+ * It only checks the sequence number of the global rename_lock as any change
+ * in the dentry's d_seq will be preceded by changes in the rename_lock
+ * sequence number. If the sequence number had been changed, it will restart
+ * the whole pathname back-tracing sequence again by taking the rename_lock.
+ * In this case, there is no need to take the RCU read lock as the recursive
+ * parent pointer references will keep the dentry chain alive as long as no
+ * rename operation is performed.
+ */
+static int prepend_path(const struct path *path,
+			const struct path *root,
+			struct prepend_buffer *p)
+{
+	unsigned seq, m_seq = 0;
+	struct prepend_buffer b;
+	int error;
+
+	rcu_read_lock();
+restart_mnt:
+	read_seqbegin_or_lock(&mount_lock, &m_seq);
+	seq = 0;
+	rcu_read_lock();
+restart:
+	b = *p;
+	read_seqbegin_or_lock(&rename_lock, &seq);
+	error = __prepend_path(path->dentry, real_mount(path->mnt), root, &b);
+	if (!(seq & 1))
+		rcu_read_unlock();
+	if (need_seqretry(&rename_lock, seq)) {
+		seq = 1;
+		goto restart;
+	}
+	done_seqretry(&rename_lock, seq);
+
+	if (!(m_seq & 1))
+		rcu_read_unlock();
+	if (need_seqretry(&mount_lock, m_seq)) {
+		m_seq = 1;
+		goto restart_mnt;
+	}
+	done_seqretry(&mount_lock, m_seq);
+
+	if (unlikely(error == 3))
+		b = *p;
+
+	if (b.len == p->len)
+		prepend_char(&b, '/');
+
+	*p = b;
+	return error;
+}
+
+/**
+ * __d_path - return the path of a dentry
+ * @path: the dentry/vfsmount to report
+ * @root: root vfsmnt/dentry
+ * @buf: buffer to return value in
+ * @buflen: buffer length
+ *
+ * Convert a dentry into an ASCII path name.
+ *
+ * Returns a pointer into the buffer or an error code if the
+ * path was too long.
+ *
+ * "buflen" should be positive.
+ *
+ * If the path is not reachable from the supplied root, return %NULL.
+ */
+char *__d_path(const struct path *path,
+	       const struct path *root,
+	       char *buf, int buflen)
+{
+	DECLARE_BUFFER(b, buf, buflen);
+
+	prepend_char(&b, 0);
+	if (unlikely(prepend_path(path, root, &b) > 0))
+		return NULL;
+	return extract_string(&b);
+}
+
+char *d_absolute_path(const struct path *path,
+	       char *buf, int buflen)
+{
+	struct path root = {};
+	DECLARE_BUFFER(b, buf, buflen);
+
+	prepend_char(&b, 0);
+	if (unlikely(prepend_path(path, &root, &b) > 1))
+		return ERR_PTR(-EINVAL);
+	return extract_string(&b);
+}
+
+static void get_fs_root_rcu(struct fs_struct *fs, struct path *root)
+{
+	unsigned seq;
+
+	do {
+		seq = read_seqcount_begin(&fs->seq);
+		*root = fs->root;
+	} while (read_seqcount_retry(&fs->seq, seq));
+}
+
+/**
+ * d_path - return the path of a dentry
+ * @path: path to report
+ * @buf: buffer to return value in
+ * @buflen: buffer length
+ *
+ * Convert a dentry into an ASCII path name. If the entry has been deleted
+ * the string " (deleted)" is appended. Note that this is ambiguous.
+ *
+ * Returns a pointer into the buffer or an error code if the path was
+ * too long. Note: Callers should use the returned pointer, not the passed
+ * in buffer, to use the name! The implementation often starts at an offset
+ * into the buffer, and may leave 0 bytes at the start.
+ *
+ * "buflen" should be positive.
+ */
+char *d_path(const struct path *path, char *buf, int buflen)
+{
+	DECLARE_BUFFER(b, buf, buflen);
+	struct path root;
+
+	/*
+	 * We have various synthetic filesystems that never get mounted.  On
+	 * these filesystems dentries are never used for lookup purposes, and
+	 * thus don't need to be hashed.  They also don't need a name until a
+	 * user wants to identify the object in /proc/pid/fd/.  The little hack
+	 * below allows us to generate a name for these objects on demand:
+	 *
+	 * Some pseudo inodes are mountable.  When they are mounted
+	 * path->dentry == path->mnt->mnt_root.  In that case don't call d_dname
+	 * and instead have d_path return the mounted path.
+	 */
+	if (path->dentry->d_op && path->dentry->d_op->d_dname &&
+	    (!IS_ROOT(path->dentry) || path->dentry != path->mnt->mnt_root))
+		return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
+
+	rcu_read_lock();
+	get_fs_root_rcu(current->fs, &root);
+	if (unlikely(d_unlinked(path->dentry)))
+		prepend(&b, " (deleted)", 11);
+	else
+		prepend_char(&b, 0);
+	prepend_path(path, &root, &b);
+	rcu_read_unlock();
+
+	return extract_string(&b);
+}
+EXPORT_SYMBOL(d_path);
+
+/*
+ * Helper function for dentry_operations.d_dname() members
+ */
+char *dynamic_dname(char *buffer, int buflen, const char *fmt, ...)
+{
+	va_list args;
+	char temp[64];
+	int sz;
+
+	va_start(args, fmt);
+	sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1;
+	va_end(args);
+
+	if (sz > sizeof(temp) || sz > buflen)
+		return ERR_PTR(-ENAMETOOLONG);
+
+	buffer += buflen - sz;
+	return memcpy(buffer, temp, sz);
+}
+
+char *simple_dname(struct dentry *dentry, char *buffer, int buflen)
+{
+	DECLARE_BUFFER(b, buffer, buflen);
+	/* these dentries are never renamed, so d_lock is not needed */
+	prepend(&b, " (deleted)", 11);
+	prepend(&b, dentry->d_name.name, dentry->d_name.len);
+	prepend_char(&b, '/');
+	return extract_string(&b);
+}
+
+/*
+ * Write full pathname from the root of the filesystem into the buffer.
+ */
+static char *__dentry_path(const struct dentry *d, struct prepend_buffer *p)
+{
+	const struct dentry *dentry;
+	struct prepend_buffer b;
+	int seq = 0;
+
+	rcu_read_lock();
+restart:
+	dentry = d;
+	b = *p;
+	read_seqbegin_or_lock(&rename_lock, &seq);
+	while (!IS_ROOT(dentry)) {
+		const struct dentry *parent = dentry->d_parent;
+
+		prefetch(parent);
+		if (!prepend_name(&b, &dentry->d_name))
+			break;
+		dentry = parent;
+	}
+	if (!(seq & 1))
+		rcu_read_unlock();
+	if (need_seqretry(&rename_lock, seq)) {
+		seq = 1;
+		goto restart;
+	}
+	done_seqretry(&rename_lock, seq);
+	if (b.len == p->len)
+		prepend_char(&b, '/');
+	return extract_string(&b);
+}
+
+char *dentry_path_raw(const struct dentry *dentry, char *buf, int buflen)
+{
+	DECLARE_BUFFER(b, buf, buflen);
+
+	prepend_char(&b, 0);
+	return __dentry_path(dentry, &b);
+}
+EXPORT_SYMBOL(dentry_path_raw);
+
+char *dentry_path(const struct dentry *dentry, char *buf, int buflen)
+{
+	DECLARE_BUFFER(b, buf, buflen);
+
+	if (unlikely(d_unlinked(dentry)))
+		prepend(&b, "//deleted", 10);
+	else
+		prepend_char(&b, 0);
+	return __dentry_path(dentry, &b);
+}
+
+static void get_fs_root_and_pwd_rcu(struct fs_struct *fs, struct path *root,
+				    struct path *pwd)
+{
+	unsigned seq;
+
+	do {
+		seq = read_seqcount_begin(&fs->seq);
+		*root = fs->root;
+		*pwd = fs->pwd;
+	} while (read_seqcount_retry(&fs->seq, seq));
+}
+
+/*
+ * NOTE! The user-level library version returns a
+ * character pointer. The kernel system call just
+ * returns the length of the buffer filled (which
+ * includes the ending '\0' character), or a negative
+ * error value. So libc would do something like
+ *
+ *	char *getcwd(char * buf, size_t size)
+ *	{
+ *		int retval;
+ *
+ *		retval = sys_getcwd(buf, size);
+ *		if (retval >= 0)
+ *			return buf;
+ *		errno = -retval;
+ *		return NULL;
+ *	}
+ */
+SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size)
+{
+	int error;
+	struct path pwd, root;
+	char *page = __getname();
+
+	if (!page)
+		return -ENOMEM;
+
+	rcu_read_lock();
+	get_fs_root_and_pwd_rcu(current->fs, &root, &pwd);
+
+	if (unlikely(d_unlinked(pwd.dentry))) {
+		rcu_read_unlock();
+		error = -ENOENT;
+	} else {
+		unsigned len;
+		DECLARE_BUFFER(b, page, PATH_MAX);
+
+		prepend_char(&b, 0);
+		if (unlikely(prepend_path(&pwd, &root, &b) > 0))
+			prepend(&b, "(unreachable)", 13);
+		rcu_read_unlock();
+
+		len = PATH_MAX - b.len;
+		if (unlikely(len > PATH_MAX))
+			error = -ENAMETOOLONG;
+		else if (unlikely(len > size))
+			error = -ERANGE;
+		else if (copy_to_user(buf, b.buf, len))
+			error = -EFAULT;
+		else
+			error = len;
+	}
+	__putname(page);
+	return error;
+}