x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 853 insertions, 0 deletions

diff --git a/fs/afs/inode.c b/fs/afs/inode.c
new file mode 100644
index 000000000..14f39a9be
--- /dev/null
+++ b/fs/afs/inode.c
@@ -0,0 +1,853 @@
+/*
+ * Copyright (c) 2002 Red Hat, Inc. All rights reserved.
+ *
+ * This software may be freely redistributed under the terms of the
+ * GNU General Public License.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ * Authors: David Woodhouse <dwmw2@infradead.org>
+ *          David Howells <dhowells@redhat.com>
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/sched.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/iversion.h>
+#include "internal.h"
+#include "afs_fs.h"
+
+static noinline void dump_vnode(struct afs_vnode *vnode, struct afs_vnode *parent_vnode)
+{
+	static unsigned long once_only;
+
+	pr_warn("kAFS: AFS vnode with undefined type %u\n", vnode->status.type);
+	pr_warn("kAFS: A=%d m=%o s=%llx v=%llx\n",
+		vnode->status.abort_code,
+		vnode->status.mode,
+		vnode->status.size,
+		vnode->status.data_version);
+	pr_warn("kAFS: vnode %llx:%llx:%x\n",
+		vnode->fid.vid,
+		vnode->fid.vnode,
+		vnode->fid.unique);
+	if (parent_vnode)
+		pr_warn("kAFS: dir %llx:%llx:%x\n",
+			parent_vnode->fid.vid,
+			parent_vnode->fid.vnode,
+			parent_vnode->fid.unique);
+
+	if (!test_and_set_bit(0, &once_only))
+		dump_stack();
+}
+
+/*
+ * Set parameters for the netfs library
+ */
+static void afs_set_netfs_context(struct afs_vnode *vnode, bool is_file)
+{
+	netfs_inode_init(&vnode->netfs, &afs_req_ops, is_file);
+}
+
+/*
+ * Initialise an inode from the vnode status.
+ */
+static int afs_inode_init_from_status(struct afs_operation *op,
+				      struct afs_vnode_param *vp,
+				      struct afs_vnode *vnode)
+{
+	struct afs_file_status *status = &vp->scb.status;
+	struct inode *inode = AFS_VNODE_TO_I(vnode);
+	struct timespec64 t;
+
+	_enter("{%llx:%llu.%u} %s",
+	       vp->fid.vid, vp->fid.vnode, vp->fid.unique,
+	       op->type ? op->type->name : "???");
+
+	_debug("FS: ft=%d lk=%d sz=%llu ver=%Lu mod=%hu",
+	       status->type,
+	       status->nlink,
+	       (unsigned long long) status->size,
+	       status->data_version,
+	       status->mode);
+
+	write_seqlock(&vnode->cb_lock);
+
+	vnode->cb_v_check = op->cb_v_break;
+	vnode->status = *status;
+
+	t = status->mtime_client;
+	inode_set_ctime_to_ts(inode, t);
+	inode_set_mtime_to_ts(inode, t);
+	inode_set_atime_to_ts(inode, t);
+	inode->i_flags |= S_NOATIME;
+	inode->i_uid = make_kuid(&init_user_ns, status->owner);
+	inode->i_gid = make_kgid(&init_user_ns, status->group);
+	set_nlink(&vnode->netfs.inode, status->nlink);
+
+	i_size_write(inode, status->size);
+	inode_set_bytes(inode, status->size);
+	afs_set_netfs_context(vnode, status->type == AFS_FTYPE_FILE);
+
+	switch (status->type) {
+	case AFS_FTYPE_FILE:
+		inode->i_mode	= S_IFREG | (status->mode & S_IALLUGO);
+		inode->i_op	= &afs_file_inode_operations;
+		inode->i_fop	= &afs_file_operations;
+		inode->i_mapping->a_ops	= &afs_file_aops;
+		mapping_set_large_folios(inode->i_mapping);
+		break;
+	case AFS_FTYPE_DIR:
+		inode->i_mode	= S_IFDIR |  (status->mode & S_IALLUGO);
+		inode->i_op	= &afs_dir_inode_operations;
+		inode->i_fop	= &afs_dir_file_operations;
+		inode->i_mapping->a_ops	= &afs_dir_aops;
+		__set_bit(NETFS_ICTX_SINGLE_NO_UPLOAD, &vnode->netfs.flags);
+		/* Assume locally cached directory data will be valid. */
+		__set_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
+		break;
+	case AFS_FTYPE_SYMLINK:
+		/* Symlinks with a mode of 0644 are actually mountpoints. */
+		if ((status->mode & 0777) == 0644) {
+			inode->i_flags |= S_AUTOMOUNT;
+
+			set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
+
+			inode->i_mode	= S_IFDIR | 0555;
+			inode->i_op	= &afs_mntpt_inode_operations;
+			inode->i_fop	= &afs_mntpt_file_operations;
+		} else {
+			inode->i_mode	= S_IFLNK | status->mode;
+			inode->i_op	= &afs_symlink_inode_operations;
+		}
+		inode->i_mapping->a_ops	= &afs_symlink_aops;
+		inode_nohighmem(inode);
+		break;
+	default:
+		dump_vnode(vnode, op->file[0].vnode != vnode ? op->file[0].vnode : NULL);
+		write_sequnlock(&vnode->cb_lock);
+		return afs_protocol_error(NULL, afs_eproto_file_type);
+	}
+
+	vnode->invalid_before	= status->data_version;
+	trace_afs_set_dv(vnode, status->data_version);
+	inode_set_iversion_raw(&vnode->netfs.inode, status->data_version);
+
+	if (!vp->scb.have_cb) {
+		/* it's a symlink we just created (the fileserver
+		 * didn't give us a callback) */
+		afs_clear_cb_promise(vnode, afs_cb_promise_set_new_symlink);
+	} else {
+		vnode->cb_server = op->server;
+		afs_set_cb_promise(vnode, vp->scb.callback.expires_at,
+				   afs_cb_promise_set_new_inode);
+	}
+
+	write_sequnlock(&vnode->cb_lock);
+	return 0;
+}
+
+/*
+ * Update the core inode struct from a returned status record.
+ */
+static void afs_apply_status(struct afs_operation *op,
+			     struct afs_vnode_param *vp)
+{
+	struct afs_file_status *status = &vp->scb.status;
+	struct afs_vnode *vnode = vp->vnode;
+	struct netfs_inode *ictx = &vnode->netfs;
+	struct inode *inode = &ictx->inode;
+	struct timespec64 t;
+	umode_t mode;
+	bool unexpected_jump = false;
+	bool data_changed = false;
+	bool change_size = vp->set_size;
+
+	_enter("{%llx:%llu.%u} %s",
+	       vp->fid.vid, vp->fid.vnode, vp->fid.unique,
+	       op->type ? op->type->name : "???");
+
+	BUG_ON(test_bit(AFS_VNODE_UNSET, &vnode->flags));
+
+	if (status->type != vnode->status.type) {
+		pr_warn("Vnode %llx:%llx:%x changed type %u to %u\n",
+			vnode->fid.vid,
+			vnode->fid.vnode,
+			vnode->fid.unique,
+			status->type, vnode->status.type);
+		afs_protocol_error(NULL, afs_eproto_bad_status);
+		return;
+	}
+
+	if (status->nlink != vnode->status.nlink)
+		set_nlink(inode, status->nlink);
+
+	if (status->owner != vnode->status.owner)
+		inode->i_uid = make_kuid(&init_user_ns, status->owner);
+
+	if (status->group != vnode->status.group)
+		inode->i_gid = make_kgid(&init_user_ns, status->group);
+
+	if (status->mode != vnode->status.mode) {
+		mode = inode->i_mode;
+		mode &= ~S_IALLUGO;
+		mode |= status->mode & S_IALLUGO;
+		WRITE_ONCE(inode->i_mode, mode);
+	}
+
+	t = status->mtime_client;
+	inode_set_mtime_to_ts(inode, t);
+	if (vp->update_ctime)
+		inode_set_ctime_to_ts(inode, op->ctime);
+
+	if (vnode->status.data_version != status->data_version) {
+		trace_afs_set_dv(vnode, status->data_version);
+		data_changed = true;
+	}
+
+	vnode->status = *status;
+
+	if (vp->dv_before + vp->dv_delta != status->data_version) {
+		trace_afs_dv_mismatch(vnode, vp->dv_before, vp->dv_delta,
+				      status->data_version);
+
+		if (vnode->cb_ro_snapshot == atomic_read(&vnode->volume->cb_ro_snapshot) &&
+		    atomic64_read(&vnode->cb_expires_at) != AFS_NO_CB_PROMISE)
+			pr_warn("kAFS: vnode modified {%llx:%llu} %llx->%llx %s (op=%x)\n",
+				vnode->fid.vid, vnode->fid.vnode,
+				(unsigned long long)vp->dv_before + vp->dv_delta,
+				(unsigned long long)status->data_version,
+				op->type ? op->type->name : "???",
+				op->debug_id);
+
+		vnode->invalid_before = status->data_version;
+		if (vnode->status.type == AFS_FTYPE_DIR)
+			afs_invalidate_dir(vnode, afs_dir_invalid_dv_mismatch);
+		else
+			set_bit(AFS_VNODE_ZAP_DATA, &vnode->flags);
+		change_size = true;
+		data_changed = true;
+		unexpected_jump = true;
+	} else if (vnode->status.type == AFS_FTYPE_DIR) {
+		/* Expected directory change is handled elsewhere so
+		 * that we can locally edit the directory and save on a
+		 * download.
+		 */
+		if (test_bit(AFS_VNODE_DIR_VALID, &vnode->flags))
+			data_changed = false;
+		change_size = true;
+	}
+
+	if (data_changed) {
+		unsigned long long zero_point, size = status->size;
+
+		inode_set_iversion_raw(inode, status->data_version);
+
+		/* Only update the size if the data version jumped.  If the
+		 * file is being modified locally, then we might have our own
+		 * idea of what the size should be that's not the same as
+		 * what's on the server.
+		 */
+		spin_lock(&inode->i_lock);
+
+		if (change_size || size > i_size_read(inode)) {
+			/* We can read the sizes directly as we hold i_lock. */
+			zero_point = ictx->_zero_point;
+
+			if (unexpected_jump)
+				zero_point = size;
+			netfs_write_sizes(inode, size, size, zero_point);
+			inode_set_bytes(inode, size);
+			inode_set_ctime_to_ts(inode, t);
+			inode_set_atime_to_ts(inode, t);
+		} else {
+			netfs_write_remote_i_size(inode, size);
+		}
+		spin_unlock(&inode->i_lock);
+
+		if (op->ops == &afs_fetch_data_operation)
+			op->fetch.subreq->rreq->i_size = size;
+	}
+}
+
+/*
+ * Apply a callback to a vnode.
+ */
+static void afs_apply_callback(struct afs_operation *op,
+			       struct afs_vnode_param *vp)
+{
+	struct afs_callback *cb = &vp->scb.callback;
+	struct afs_vnode *vnode = vp->vnode;
+
+	if (!afs_cb_is_broken(vp->cb_break_before, vnode)) {
+		if (op->volume->type == AFSVL_RWVOL)
+			vnode->cb_server = op->server;
+		afs_set_cb_promise(vnode, cb->expires_at, afs_cb_promise_set_apply_cb);
+	}
+}
+
+/*
+ * Apply the received status and callback to an inode all in the same critical
+ * section to avoid races with afs_validate().
+ */
+void afs_vnode_commit_status(struct afs_operation *op, struct afs_vnode_param *vp)
+{
+	struct afs_vnode *vnode = vp->vnode;
+
+	_enter("");
+
+	write_seqlock(&vnode->cb_lock);
+
+	if (vp->scb.have_error) {
+		/* A YFS server will return this from RemoveFile2 and AFS and
+		 * YFS will return this from InlineBulkStatus.
+		 */
+		if (vp->scb.status.abort_code == VNOVNODE) {
+			set_bit(AFS_VNODE_DELETED, &vnode->flags);
+			clear_nlink(&vnode->netfs.inode);
+			__afs_break_callback(vnode, afs_cb_break_for_deleted);
+			op->flags &= ~AFS_OPERATION_DIR_CONFLICT;
+		}
+	} else if (vp->scb.have_status) {
+		if (vp->speculative &&
+		    (test_bit(AFS_VNODE_MODIFYING, &vnode->flags) ||
+		     vp->dv_before != vnode->status.data_version))
+			/* Ignore the result of a speculative bulk status fetch
+			 * if it splits around a modification op, thereby
+			 * appearing to regress the data version.
+			 */
+			goto out;
+		afs_apply_status(op, vp);
+		if (vp->scb.have_cb)
+			afs_apply_callback(op, vp);
+	} else if (vp->op_unlinked && !(op->flags & AFS_OPERATION_DIR_CONFLICT)) {
+		drop_nlink(&vnode->netfs.inode);
+		if (vnode->netfs.inode.i_nlink == 0) {
+			set_bit(AFS_VNODE_DELETED, &vnode->flags);
+			__afs_break_callback(vnode, afs_cb_break_for_deleted);
+		}
+	}
+
+out:
+	write_sequnlock(&vnode->cb_lock);
+
+	if (vp->scb.have_status)
+		afs_cache_permit(vnode, op->key, vp->cb_break_before, &vp->scb);
+}
+
+static void afs_fetch_status_success(struct afs_operation *op)
+{
+	struct afs_vnode_param *vp = &op->file[op->fetch_status.which];
+	struct afs_vnode *vnode = vp->vnode;
+	int ret;
+
+	if (inode_state_read_once(&vnode->netfs.inode) & I_NEW) {
+		ret = afs_inode_init_from_status(op, vp, vnode);
+		afs_op_set_error(op, ret);
+		if (ret == 0)
+			afs_cache_permit(vnode, op->key, vp->cb_break_before, &vp->scb);
+	} else {
+		afs_vnode_commit_status(op, vp);
+	}
+}
+
+const struct afs_operation_ops afs_fetch_status_operation = {
+	.issue_afs_rpc	= afs_fs_fetch_status,
+	.issue_yfs_rpc	= yfs_fs_fetch_status,
+	.success	= afs_fetch_status_success,
+	.aborted	= afs_check_for_remote_deletion,
+};
+
+/*
+ * Fetch file status from the volume.
+ */
+int afs_fetch_status(struct afs_vnode *vnode, struct key *key, bool is_new,
+		     afs_access_t *_caller_access)
+{
+	struct afs_operation *op;
+
+	_enter("%s,{%llx:%llu.%u,S=%lx}",
+	       vnode->volume->name,
+	       vnode->fid.vid, vnode->fid.vnode, vnode->fid.unique,
+	       vnode->flags);
+
+	op = afs_alloc_operation(key, vnode->volume);
+	if (IS_ERR(op))
+		return PTR_ERR(op);
+
+	afs_op_set_vnode(op, 0, vnode);
+
+	op->nr_files	= 1;
+	op->ops		= &afs_fetch_status_operation;
+	afs_begin_vnode_operation(op);
+	afs_wait_for_operation(op);
+
+	if (_caller_access)
+		*_caller_access = op->file[0].scb.status.caller_access;
+	return afs_put_operation(op);
+}
+
+/*
+ * ilookup() comparator
+ */
+int afs_ilookup5_test_by_fid(struct inode *inode, void *opaque)
+{
+	struct afs_vnode *vnode = AFS_FS_I(inode);
+	struct afs_fid *fid = opaque;
+
+	return (fid->vnode == vnode->fid.vnode &&
+		fid->vnode_hi == vnode->fid.vnode_hi &&
+		fid->unique == vnode->fid.unique);
+}
+
+/*
+ * iget5() comparator
+ */
+static int afs_iget5_test(struct inode *inode, void *opaque)
+{
+	struct afs_vnode_param *vp = opaque;
+	//struct afs_vnode *vnode = AFS_FS_I(inode);
+
+	return afs_ilookup5_test_by_fid(inode, &vp->fid);
+}
+
+/*
+ * iget5() inode initialiser
+ */
+static int afs_iget5_set(struct inode *inode, void *opaque)
+{
+	struct afs_vnode_param *vp = opaque;
+	struct afs_super_info *as = AFS_FS_S(inode->i_sb);
+	struct afs_vnode *vnode = AFS_FS_I(inode);
+
+	vnode->volume		= as->volume;
+	vnode->fid		= vp->fid;
+
+	/* YFS supports 96-bit vnode IDs, but Linux only supports
+	 * 64-bit inode numbers.
+	 */
+	inode->i_ino		= vnode->fid.vnode;
+	inode->i_generation	= vnode->fid.unique;
+	return 0;
+}
+
+/*
+ * Get a cache cookie for an inode.
+ */
+static void afs_get_inode_cache(struct afs_vnode *vnode)
+{
+#ifdef CONFIG_AFS_FSCACHE
+	struct {
+		__be32 vnode_id;
+		__be32 unique;
+		__be32 vnode_id_ext[2];	/* Allow for a 96-bit key */
+	} __packed key;
+	struct afs_vnode_cache_aux aux;
+
+	if (vnode->status.type != AFS_FTYPE_FILE &&
+	    vnode->status.type != AFS_FTYPE_DIR &&
+	    vnode->status.type != AFS_FTYPE_SYMLINK) {
+		vnode->netfs.cache = NULL;
+		return;
+	}
+
+	key.vnode_id		= htonl(vnode->fid.vnode);
+	key.unique		= htonl(vnode->fid.unique);
+	key.vnode_id_ext[0]	= htonl(vnode->fid.vnode >> 32);
+	key.vnode_id_ext[1]	= htonl(vnode->fid.vnode_hi);
+	afs_set_cache_aux(vnode, &aux);
+
+	afs_vnode_set_cache(vnode,
+			    fscache_acquire_cookie(
+				    vnode->volume->cache,
+				    vnode->status.type == AFS_FTYPE_FILE ?
+				    0 : FSCACHE_ADV_SINGLE_CHUNK,
+				    &key, sizeof(key),
+				    &aux, sizeof(aux),
+				    i_size_read(&vnode->netfs.inode)));
+#endif
+}
+
+/*
+ * inode retrieval
+ */
+struct inode *afs_iget(struct afs_operation *op, struct afs_vnode_param *vp)
+{
+	struct afs_vnode_param *dvp = &op->file[0];
+	struct super_block *sb = dvp->vnode->netfs.inode.i_sb;
+	struct afs_vnode *vnode;
+	struct inode *inode;
+	int ret;
+
+	_enter(",{%llx:%llu.%u},,", vp->fid.vid, vp->fid.vnode, vp->fid.unique);
+
+	inode = iget5_locked(sb, vp->fid.vnode, afs_iget5_test, afs_iget5_set, vp);
+	if (!inode) {
+		_leave(" = -ENOMEM");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	vnode = AFS_FS_I(inode);
+
+	_debug("GOT INODE %p { vl=%llx vn=%llx, u=%x }",
+	       inode, vnode->fid.vid, vnode->fid.vnode, vnode->fid.unique);
+
+	/* deal with an existing inode */
+	if (!(inode_state_read_once(inode) & I_NEW)) {
+		_leave(" = %p", inode);
+		return inode;
+	}
+
+	ret = afs_inode_init_from_status(op, vp, vnode);
+	if (ret < 0)
+		goto bad_inode;
+
+	afs_get_inode_cache(vnode);
+
+	/* success */
+	clear_bit(AFS_VNODE_UNSET, &vnode->flags);
+	unlock_new_inode(inode);
+	_leave(" = %p", inode);
+	return inode;
+
+	/* failure */
+bad_inode:
+	iget_failed(inode);
+	_leave(" = %d [bad]", ret);
+	return ERR_PTR(ret);
+}
+
+static int afs_iget5_set_root(struct inode *inode, void *opaque)
+{
+	struct afs_super_info *as = AFS_FS_S(inode->i_sb);
+	struct afs_vnode *vnode = AFS_FS_I(inode);
+
+	vnode->volume		= as->volume;
+	vnode->fid.vid		= as->volume->vid;
+	vnode->fid.vnode	= 1;
+	vnode->fid.unique	= 1;
+	inode->i_ino		= 1;
+	inode->i_generation	= 1;
+	return 0;
+}
+
+/*
+ * Set up the root inode for a volume.  This is always vnode 1, unique 1 within
+ * the volume.
+ */
+struct inode *afs_root_iget(struct super_block *sb, struct key *key)
+{
+	struct afs_super_info *as = AFS_FS_S(sb);
+	struct afs_operation *op;
+	struct afs_vnode *vnode;
+	struct inode *inode;
+	int ret;
+
+	_enter(",{%llx},,", as->volume->vid);
+
+	inode = iget5_locked(sb, 1, NULL, afs_iget5_set_root, NULL);
+	if (!inode) {
+		_leave(" = -ENOMEM");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	_debug("GOT ROOT INODE %p { vl=%llx }", inode, as->volume->vid);
+
+	BUG_ON(!(inode_state_read_once(inode) & I_NEW));
+
+	vnode = AFS_FS_I(inode);
+	vnode->cb_v_check = atomic_read(&as->volume->cb_v_break);
+
+	op = afs_alloc_operation(key, as->volume);
+	if (IS_ERR(op)) {
+		ret = PTR_ERR(op);
+		goto error;
+	}
+
+	afs_op_set_vnode(op, 0, vnode);
+
+	op->nr_files	= 1;
+	op->ops		= &afs_fetch_status_operation;
+	ret = afs_do_sync_operation(op);
+	if (ret < 0)
+		goto error;
+
+	afs_get_inode_cache(vnode);
+
+	clear_bit(AFS_VNODE_UNSET, &vnode->flags);
+	unlock_new_inode(inode);
+	_leave(" = %p", inode);
+	return inode;
+
+error:
+	iget_failed(inode);
+	_leave(" = %d [bad]", ret);
+	return ERR_PTR(ret);
+}
+
+/*
+ * read the attributes of an inode
+ */
+int afs_getattr(struct mnt_idmap *idmap, const struct path *path,
+		struct kstat *stat, u32 request_mask, unsigned int query_flags)
+{
+	struct inode *inode = d_inode(path->dentry);
+	struct afs_vnode *vnode = AFS_FS_I(inode);
+	struct key *key;
+	int ret, seq;
+
+	_enter("{ ino=%llu v=%u }", inode->i_ino, inode->i_generation);
+
+	if (vnode->volume &&
+	    !(query_flags & AT_STATX_DONT_SYNC) &&
+	    atomic64_read(&vnode->cb_expires_at) == AFS_NO_CB_PROMISE) {
+		key = afs_request_key(vnode->volume->cell);
+		if (IS_ERR(key))
+			return PTR_ERR(key);
+		ret = afs_validate(vnode, key);
+		key_put(key);
+		if (ret < 0)
+			return ret;
+	}
+
+	do {
+		seq = read_seqbegin(&vnode->cb_lock);
+		generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
+		if (test_bit(AFS_VNODE_SILLY_DELETED, &vnode->flags) &&
+		    stat->nlink > 0)
+			stat->nlink -= 1;
+
+		/* Lie about the size of directories.  We maintain a locally
+		 * edited copy and may make different allocation decisions on
+		 * it, but we need to give userspace the server's size.
+		 */
+		if (S_ISDIR(inode->i_mode))
+			stat->size = netfs_read_remote_i_size(inode);
+	} while (read_seqretry(&vnode->cb_lock, seq));
+
+	return 0;
+}
+
+/*
+ * discard an AFS inode
+ */
+int afs_drop_inode(struct inode *inode)
+{
+	_enter("");
+
+	if (test_bit(AFS_VNODE_PSEUDODIR, &AFS_FS_I(inode)->flags))
+		return inode_just_drop(inode);
+	else
+		return inode_generic_drop(inode);
+}
+
+/*
+ * clear an AFS inode
+ */
+void afs_evict_inode(struct inode *inode)
+{
+	struct afs_vnode_cache_aux aux;
+	struct afs_super_info *sbi = AFS_FS_S(inode->i_sb);
+	struct afs_vnode *vnode = AFS_FS_I(inode);
+
+	_enter("{%llx:%llu.%d}",
+	       vnode->fid.vid,
+	       vnode->fid.vnode,
+	       vnode->fid.unique);
+
+	_debug("CLEAR INODE %p", inode);
+
+	ASSERTCMP(inode->i_ino, ==, vnode->fid.vnode);
+
+	if ((S_ISDIR(inode->i_mode) ||
+	     S_ISLNK(inode->i_mode)) &&
+	    (inode_state_read_once(inode) & I_DIRTY) &&
+	    !sbi->dyn_root) {
+		struct writeback_control wbc = {
+			.sync_mode = WB_SYNC_ALL,
+			.for_sync = true,
+			.range_end = LLONG_MAX,
+		};
+
+		inode->i_mapping->a_ops->writepages(inode->i_mapping, &wbc);
+	}
+
+	flush_delayed_work(&vnode->lock_work);
+	netfs_wait_for_outstanding_io(inode);
+	truncate_inode_pages_final(&inode->i_data);
+	netfs_free_folioq_buffer(vnode->directory);
+	if (vnode->symlink)
+		afs_evict_symlink(vnode);
+
+	afs_set_cache_aux(vnode, &aux);
+	netfs_clear_inode_writeback(inode, &aux);
+	clear_inode(inode);
+
+	while (!list_empty(&vnode->wb_keys)) {
+		struct afs_wb_key *wbk = list_entry(vnode->wb_keys.next,
+						    struct afs_wb_key, vnode_link);
+		list_del(&wbk->vnode_link);
+		afs_put_wb_key(wbk);
+	}
+
+	fscache_relinquish_cookie(afs_vnode_cache(vnode),
+				  test_bit(AFS_VNODE_DELETED, &vnode->flags));
+
+	afs_prune_wb_keys(vnode);
+	afs_put_permits(rcu_access_pointer(vnode->permit_cache));
+	key_put(vnode->silly_key);
+	vnode->silly_key = NULL;
+	key_put(vnode->lock_key);
+	vnode->lock_key = NULL;
+	_leave("");
+}
+
+static void afs_setattr_success(struct afs_operation *op)
+{
+	struct afs_vnode_param *vp = &op->file[0];
+	struct inode *inode = &vp->vnode->netfs.inode;
+	loff_t old_i_size = i_size_read(inode);
+
+	op->setattr.old_i_size = old_i_size;
+	afs_vnode_commit_status(op, vp);
+	/* inode->i_size has now been changed. */
+
+	if (op->setattr.attr->ia_valid & ATTR_SIZE) {
+		loff_t size = op->setattr.attr->ia_size;
+		if (size > old_i_size)
+			pagecache_isize_extended(inode, old_i_size, size);
+	}
+}
+
+static void afs_setattr_edit_file(struct afs_operation *op)
+{
+	struct afs_vnode_param *vp = &op->file[0];
+	struct afs_vnode *vnode = vp->vnode;
+	struct inode *inode = &vnode->netfs.inode;
+
+	if (op->setattr.attr->ia_valid & ATTR_SIZE) {
+		loff_t size = op->setattr.attr->ia_size;
+		loff_t old = op->setattr.old_i_size;
+
+		/* Note: inode->i_size was updated by afs_apply_status() inside
+		 * the I/O and callback locks.
+		 */
+
+		if (size != old) {
+			truncate_pagecache(inode, size);
+			netfs_resize_file(&vnode->netfs, size, true);
+			fscache_resize_cookie(afs_vnode_cache(vnode), size);
+		}
+	}
+}
+
+static const struct afs_operation_ops afs_setattr_operation = {
+	.issue_afs_rpc	= afs_fs_setattr,
+	.issue_yfs_rpc	= yfs_fs_setattr,
+	.success	= afs_setattr_success,
+	.edit_dir	= afs_setattr_edit_file,
+};
+
+/*
+ * set the attributes of an inode
+ */
+int afs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
+		struct iattr *attr)
+{
+	const unsigned int supported =
+		ATTR_SIZE | ATTR_MODE | ATTR_UID | ATTR_GID |
+		ATTR_MTIME | ATTR_MTIME_SET | ATTR_TIMES_SET | ATTR_TOUCH;
+	struct afs_operation *op;
+	struct afs_vnode *vnode = AFS_FS_I(d_inode(dentry));
+	struct inode *inode = &vnode->netfs.inode;
+	loff_t i_size;
+	int ret;
+
+	_enter("{%llx:%llu},{n=%pd},%x",
+	       vnode->fid.vid, vnode->fid.vnode, dentry,
+	       attr->ia_valid);
+
+	if (!(attr->ia_valid & supported)) {
+		_leave(" = 0 [unsupported]");
+		return 0;
+	}
+
+	i_size = i_size_read(inode);
+	if (attr->ia_valid & ATTR_SIZE) {
+		if (!S_ISREG(inode->i_mode))
+			return -EISDIR;
+
+		ret = inode_newsize_ok(inode, attr->ia_size);
+		if (ret)
+			return ret;
+
+		if (attr->ia_size == i_size)
+			attr->ia_valid &= ~ATTR_SIZE;
+	}
+
+	fscache_use_cookie(afs_vnode_cache(vnode), true);
+
+	/* Prevent any new writebacks from starting whilst we do this. */
+	down_write(&vnode->validate_lock);
+
+	if ((attr->ia_valid & ATTR_SIZE) && S_ISREG(inode->i_mode)) {
+		loff_t size = attr->ia_size;
+
+		/* Wait for any outstanding writes to the server to complete */
+		loff_t from = min(size, i_size);
+		loff_t to = max(size, i_size);
+		ret = filemap_fdatawait_range(inode->i_mapping, from, to);
+		if (ret < 0)
+			goto out_unlock;
+
+		/* Don't talk to the server if we're just shortening in-memory
+		 * writes that haven't gone to the server yet.
+		 */
+		if (!(attr->ia_valid & (supported & ~ATTR_SIZE & ~ATTR_MTIME)) &&
+		    attr->ia_size < i_size &&
+		    attr->ia_size > netfs_read_remote_i_size(inode)) {
+			truncate_setsize(inode, attr->ia_size);
+			netfs_resize_file(&vnode->netfs, size, false);
+			fscache_resize_cookie(afs_vnode_cache(vnode),
+					      attr->ia_size);
+			ret = 0;
+			goto out_unlock;
+		}
+	}
+
+	op = afs_alloc_operation(((attr->ia_valid & ATTR_FILE) ?
+				  afs_file_key(attr->ia_file) : NULL),
+				 vnode->volume);
+	if (IS_ERR(op)) {
+		ret = PTR_ERR(op);
+		goto out_unlock;
+	}
+
+	afs_op_set_vnode(op, 0, vnode);
+	op->setattr.attr = attr;
+
+	if (attr->ia_valid & ATTR_SIZE) {
+		op->file[0].dv_delta = 1;
+		op->file[0].set_size = true;
+	}
+	op->ctime = attr->ia_ctime;
+	op->file[0].update_ctime = 1;
+	op->file[0].modification = true;
+
+	op->ops = &afs_setattr_operation;
+	ret = afs_do_sync_operation(op);
+
+out_unlock:
+	up_write(&vnode->validate_lock);
+	fscache_unuse_cookie(afs_vnode_cache(vnode), NULL, NULL);
+	_leave(" = %d", ret);
+	return ret;
+}