Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 1402 insertions, 0 deletions

diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
new file mode 100644
index 000000000..3829554ca
--- /dev/null
+++ b/fs/9p/vfs_inode.c
@@ -0,0 +1,1402 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * This file contains vfs inode ops for the 9P2000 protocol.
+ *
+ *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
+ *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/pagemap.h>
+#include <linux/stat.h>
+#include <linux/string.h>
+#include <linux/namei.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/xattr.h>
+#include <linux/posix_acl.h>
+#include <net/9p/9p.h>
+#include <net/9p/client.h>
+
+#include "v9fs.h"
+#include "v9fs_vfs.h"
+#include "fid.h"
+#include "cache.h"
+#include "xattr.h"
+#include "acl.h"
+
+static const struct inode_operations v9fs_dir_inode_operations;
+static const struct inode_operations v9fs_dir_inode_operations_dotu;
+static const struct inode_operations v9fs_file_inode_operations;
+static const struct inode_operations v9fs_symlink_inode_operations;
+
+/**
+ * unixmode2p9mode - convert unix mode bits to plan 9
+ * @v9ses: v9fs session information
+ * @mode: mode to convert
+ *
+ */
+
+static u32 unixmode2p9mode(struct v9fs_session_info *v9ses, umode_t mode)
+{
+	int res;
+
+	res = mode & 0777;
+	if (S_ISDIR(mode))
+		res |= P9_DMDIR;
+	if (v9fs_proto_dotu(v9ses)) {
+		if (v9ses->nodev == 0) {
+			if (S_ISSOCK(mode))
+				res |= P9_DMSOCKET;
+			if (S_ISFIFO(mode))
+				res |= P9_DMNAMEDPIPE;
+			if (S_ISBLK(mode))
+				res |= P9_DMDEVICE;
+			if (S_ISCHR(mode))
+				res |= P9_DMDEVICE;
+		}
+
+		if ((mode & S_ISUID) == S_ISUID)
+			res |= P9_DMSETUID;
+		if ((mode & S_ISGID) == S_ISGID)
+			res |= P9_DMSETGID;
+		if ((mode & S_ISVTX) == S_ISVTX)
+			res |= P9_DMSETVTX;
+	}
+	return res;
+}
+
+/**
+ * p9mode2perm- convert plan9 mode bits to unix permission bits
+ * @v9ses: v9fs session information
+ * @stat: p9_wstat from which mode need to be derived
+ *
+ */
+static int p9mode2perm(struct v9fs_session_info *v9ses,
+		       struct p9_wstat *stat)
+{
+	int res;
+	int mode = stat->mode;
+
+	res = mode & 0777; /* S_IRWXUGO */
+	if (v9fs_proto_dotu(v9ses)) {
+		if ((mode & P9_DMSETUID) == P9_DMSETUID)
+			res |= S_ISUID;
+
+		if ((mode & P9_DMSETGID) == P9_DMSETGID)
+			res |= S_ISGID;
+
+		if ((mode & P9_DMSETVTX) == P9_DMSETVTX)
+			res |= S_ISVTX;
+	}
+	return res;
+}
+
+/**
+ * p9mode2unixmode- convert plan9 mode bits to unix mode bits
+ * @v9ses: v9fs session information
+ * @stat: p9_wstat from which mode need to be derived
+ * @rdev: major number, minor number in case of device files.
+ *
+ */
+static umode_t p9mode2unixmode(struct v9fs_session_info *v9ses,
+			       struct p9_wstat *stat, dev_t *rdev)
+{
+	int res, r;
+	u32 mode = stat->mode;
+
+	*rdev = 0;
+	res = p9mode2perm(v9ses, stat);
+
+	if ((mode & P9_DMDIR) == P9_DMDIR)
+		res |= S_IFDIR;
+	else if ((mode & P9_DMSYMLINK) && (v9fs_proto_dotu(v9ses)))
+		res |= S_IFLNK;
+	else if ((mode & P9_DMSOCKET) && (v9fs_proto_dotu(v9ses))
+		 && (v9ses->nodev == 0))
+		res |= S_IFSOCK;
+	else if ((mode & P9_DMNAMEDPIPE) && (v9fs_proto_dotu(v9ses))
+		 && (v9ses->nodev == 0))
+		res |= S_IFIFO;
+	else if ((mode & P9_DMDEVICE) && (v9fs_proto_dotu(v9ses))
+		 && (v9ses->nodev == 0)) {
+		char type = 0;
+		int major = -1, minor = -1;
+
+		r = sscanf(stat->extension, "%c %i %i", &type, &major, &minor);
+		if (r != 3) {
+			p9_debug(P9_DEBUG_ERROR,
+				 "invalid device string, umode will be bogus: %s\n",
+				 stat->extension);
+			return res;
+		}
+		switch (type) {
+		case 'c':
+			res |= S_IFCHR;
+			break;
+		case 'b':
+			res |= S_IFBLK;
+			break;
+		default:
+			p9_debug(P9_DEBUG_ERROR, "Unknown special type %c %s\n",
+				 type, stat->extension);
+		}
+		*rdev = MKDEV(major, minor);
+	} else
+		res |= S_IFREG;
+
+	return res;
+}
+
+/**
+ * v9fs_uflags2omode- convert posix open flags to plan 9 mode bits
+ * @uflags: flags to convert
+ * @extended: if .u extensions are active
+ */
+
+int v9fs_uflags2omode(int uflags, int extended)
+{
+	int ret;
+
+	switch (uflags&3) {
+	default:
+	case O_RDONLY:
+		ret = P9_OREAD;
+		break;
+
+	case O_WRONLY:
+		ret = P9_OWRITE;
+		break;
+
+	case O_RDWR:
+		ret = P9_ORDWR;
+		break;
+	}
+
+	if (uflags & O_TRUNC)
+		ret |= P9_OTRUNC;
+
+	if (extended) {
+		if (uflags & O_EXCL)
+			ret |= P9_OEXCL;
+
+		if (uflags & O_APPEND)
+			ret |= P9_OAPPEND;
+	}
+
+	return ret;
+}
+
+/**
+ * v9fs_blank_wstat - helper function to setup a 9P stat structure
+ * @wstat: structure to initialize
+ *
+ */
+
+void
+v9fs_blank_wstat(struct p9_wstat *wstat)
+{
+	wstat->type = ~0;
+	wstat->dev = ~0;
+	wstat->qid.type = ~0;
+	wstat->qid.version = ~0;
+	*((long long *)&wstat->qid.path) = ~0;
+	wstat->mode = ~0;
+	wstat->atime = ~0;
+	wstat->mtime = ~0;
+	wstat->length = ~0;
+	wstat->name = NULL;
+	wstat->uid = NULL;
+	wstat->gid = NULL;
+	wstat->muid = NULL;
+	wstat->n_uid = INVALID_UID;
+	wstat->n_gid = INVALID_GID;
+	wstat->n_muid = INVALID_UID;
+	wstat->extension = NULL;
+}
+
+/**
+ * v9fs_alloc_inode - helper function to allocate an inode
+ * @sb: The superblock to allocate the inode from
+ */
+struct inode *v9fs_alloc_inode(struct super_block *sb)
+{
+	struct v9fs_inode *v9inode;
+
+	v9inode = alloc_inode_sb(sb, v9fs_inode_cache, GFP_KERNEL);
+	if (!v9inode)
+		return NULL;
+	v9inode->cache_validity = 0;
+	mutex_init(&v9inode->v_mutex);
+	return &v9inode->netfs.inode;
+}
+
+/**
+ * v9fs_free_inode - destroy an inode
+ * @inode: The inode to be freed
+ */
+
+void v9fs_free_inode(struct inode *inode)
+{
+	kmem_cache_free(v9fs_inode_cache, V9FS_I(inode));
+}
+
+/*
+ * Set parameters for the netfs library
+ */
+void v9fs_set_netfs_context(struct inode *inode)
+{
+	struct v9fs_inode *v9inode = V9FS_I(inode);
+	netfs_inode_init(&v9inode->netfs, &v9fs_req_ops, true);
+}
+
+int v9fs_init_inode(struct v9fs_session_info *v9ses,
+		    struct inode *inode, umode_t mode, dev_t rdev)
+{
+	int err = 0;
+
+	inode_init_owner(&nop_mnt_idmap, inode, NULL, mode);
+	inode->i_blocks = 0;
+	inode->i_rdev = rdev;
+	simple_inode_init_ts(inode);
+	inode->i_mapping->a_ops = &v9fs_addr_operations;
+	inode->i_private = NULL;
+
+	switch (mode & S_IFMT) {
+	case S_IFIFO:
+	case S_IFBLK:
+	case S_IFCHR:
+	case S_IFSOCK:
+		if (v9fs_proto_dotl(v9ses)) {
+			inode->i_op = &v9fs_file_inode_operations_dotl;
+		} else if (v9fs_proto_dotu(v9ses)) {
+			inode->i_op = &v9fs_file_inode_operations;
+		} else {
+			p9_debug(P9_DEBUG_ERROR,
+				 "special files without extended mode\n");
+			err = -EINVAL;
+			goto error;
+		}
+		init_special_inode(inode, inode->i_mode, inode->i_rdev);
+		break;
+	case S_IFREG:
+		if (v9fs_proto_dotl(v9ses)) {
+			inode->i_op = &v9fs_file_inode_operations_dotl;
+			inode->i_fop = &v9fs_file_operations_dotl;
+		} else {
+			inode->i_op = &v9fs_file_inode_operations;
+			inode->i_fop = &v9fs_file_operations;
+		}
+
+		break;
+	case S_IFLNK:
+		if (!v9fs_proto_dotu(v9ses) && !v9fs_proto_dotl(v9ses)) {
+			p9_debug(P9_DEBUG_ERROR,
+				 "extended modes used with legacy protocol\n");
+			err = -EINVAL;
+			goto error;
+		}
+
+		if (v9fs_proto_dotl(v9ses)) {
+			inode->i_op = &v9fs_symlink_inode_operations_dotl;
+			inode_nohighmem(inode);
+		} else {
+			inode->i_op = &v9fs_symlink_inode_operations;
+		}
+
+		break;
+	case S_IFDIR:
+		inc_nlink(inode);
+		if (v9fs_proto_dotl(v9ses))
+			inode->i_op = &v9fs_dir_inode_operations_dotl;
+		else if (v9fs_proto_dotu(v9ses))
+			inode->i_op = &v9fs_dir_inode_operations_dotu;
+		else
+			inode->i_op = &v9fs_dir_inode_operations;
+
+		if (v9fs_proto_dotl(v9ses))
+			inode->i_fop = &v9fs_dir_operations_dotl;
+		else
+			inode->i_fop = &v9fs_dir_operations;
+
+		break;
+	default:
+		p9_debug(P9_DEBUG_ERROR, "BAD mode 0x%hx S_IFMT 0x%x\n",
+			 mode, mode & S_IFMT);
+		err = -EINVAL;
+		goto error;
+	}
+error:
+	return err;
+
+}
+
+/**
+ * v9fs_evict_inode - Remove an inode from the inode cache
+ * @inode: inode to release
+ *
+ */
+void v9fs_evict_inode(struct inode *inode)
+{
+	struct v9fs_inode __maybe_unused *v9inode = V9FS_I(inode);
+	__le32 __maybe_unused version;
+
+	if (!is_bad_inode(inode)) {
+		netfs_wait_for_outstanding_io(inode);
+		truncate_inode_pages_final(&inode->i_data);
+
+		version = cpu_to_le32(v9inode->qid.version);
+		netfs_clear_inode_writeback(inode, &version);
+
+		clear_inode(inode);
+		filemap_fdatawrite(&inode->i_data);
+
+#ifdef CONFIG_9P_FSCACHE
+		if (v9fs_inode_cookie(v9inode))
+			fscache_relinquish_cookie(v9fs_inode_cookie(v9inode), false);
+#endif
+	} else
+		clear_inode(inode);
+}
+
+static int v9fs_test_inode(struct inode *inode, void *data)
+{
+	int umode;
+	dev_t rdev;
+	struct v9fs_inode *v9inode = V9FS_I(inode);
+	struct p9_wstat *st = (struct p9_wstat *)data;
+	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
+
+	umode = p9mode2unixmode(v9ses, st, &rdev);
+	/* don't match inode of different type */
+	if (inode_wrong_type(inode, umode))
+		return 0;
+
+	/* compare qid details */
+	if (memcmp(&v9inode->qid.version,
+		   &st->qid.version, sizeof(v9inode->qid.version)))
+		return 0;
+
+	if (v9inode->qid.type != st->qid.type)
+		return 0;
+
+	if (v9inode->qid.path != st->qid.path)
+		return 0;
+	return 1;
+}
+
+static int v9fs_test_new_inode(struct inode *inode, void *data)
+{
+	return 0;
+}
+
+static int v9fs_set_inode(struct inode *inode,  void *data)
+{
+	struct v9fs_inode *v9inode = V9FS_I(inode);
+	struct p9_wstat *st = (struct p9_wstat *)data;
+
+	memcpy(&v9inode->qid, &st->qid, sizeof(st->qid));
+	return 0;
+}
+
+static struct inode *v9fs_qid_iget(struct super_block *sb,
+				   struct p9_qid *qid,
+				   struct p9_wstat *st,
+				   int new)
+{
+	dev_t rdev;
+	int retval;
+	umode_t umode;
+	struct inode *inode;
+	struct v9fs_session_info *v9ses = sb->s_fs_info;
+	int (*test)(struct inode *inode, void *data);
+
+	if (new)
+		test = v9fs_test_new_inode;
+	else
+		test = v9fs_test_inode;
+
+	inode = iget5_locked(sb, QID2INO(qid), test, v9fs_set_inode, st);
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+	if (!(inode_state_read_once(inode) & I_NEW))
+		return inode;
+	/*
+	 * initialize the inode with the stat info
+	 * FIXME!! we may need support for stale inodes
+	 * later.
+	 */
+	inode->i_ino = QID2INO(qid);
+	umode = p9mode2unixmode(v9ses, st, &rdev);
+	retval = v9fs_init_inode(v9ses, inode, umode, rdev);
+	if (retval)
+		goto error;
+
+	v9fs_stat2inode(st, inode, sb, 0);
+	v9fs_set_netfs_context(inode);
+	v9fs_cache_inode_get_cookie(inode);
+	unlock_new_inode(inode);
+	return inode;
+error:
+	iget_failed(inode);
+	return ERR_PTR(retval);
+
+}
+
+struct inode *
+v9fs_inode_from_fid(struct v9fs_session_info *v9ses, struct p9_fid *fid,
+		    struct super_block *sb, int new)
+{
+	struct p9_wstat *st;
+	struct inode *inode = NULL;
+
+	st = p9_client_stat(fid);
+	if (IS_ERR(st))
+		return ERR_CAST(st);
+
+	inode = v9fs_qid_iget(sb, &st->qid, st, new);
+	p9stat_free(st);
+	kfree(st);
+	return inode;
+}
+
+/**
+ * v9fs_at_to_dotl_flags- convert Linux specific AT flags to
+ * plan 9 AT flag.
+ * @flags: flags to convert
+ */
+static int v9fs_at_to_dotl_flags(int flags)
+{
+	int rflags = 0;
+
+	if (flags & AT_REMOVEDIR)
+		rflags |= P9_DOTL_AT_REMOVEDIR;
+
+	return rflags;
+}
+
+/**
+ * v9fs_dec_count - helper functon to drop i_nlink.
+ *
+ * If a directory had nlink <= 2 (including . and ..), then we should not drop
+ * the link count, which indicates the underlying exported fs doesn't maintain
+ * nlink accurately. e.g.
+ * - overlayfs sets nlink to 1 for merged dir
+ * - ext4 (with dir_nlink feature enabled) sets nlink to 1 if a dir has more
+ *   than EXT4_LINK_MAX (65000) links.
+ *
+ * In cacheless mode the server is the source of truth for nlink and the
+ * inode is going away immediately, so locally adjusting i_nlink buys
+ * nothing and races with concurrent metadata fetches that may already
+ * have observed the post-unlink value (nlink == 0).
+ *
+ * @inode: inode whose nlink is being dropped
+ */
+static void v9fs_dec_count(struct inode *inode)
+{
+	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
+
+	if (!(v9ses->cache & (CACHE_META | CACHE_LOOSE)))
+		return;
+	if (!S_ISDIR(inode->i_mode) || inode->i_nlink > 2)
+		drop_nlink(inode);
+}
+
+/**
+ * v9fs_remove - helper function to remove files and directories
+ * @dir: directory inode that is being deleted
+ * @dentry:  dentry that is being deleted
+ * @flags: removing a directory
+ *
+ */
+
+static int v9fs_remove(struct inode *dir, struct dentry *dentry, int flags)
+{
+	struct inode *inode;
+	int retval = -EOPNOTSUPP;
+	struct p9_fid *v9fid, *dfid;
+	struct v9fs_session_info *v9ses;
+
+	p9_debug(P9_DEBUG_VFS, "inode: %p dentry: %p rmdir: %x\n",
+		 dir, dentry, flags);
+
+	v9ses = v9fs_inode2v9ses(dir);
+	inode = d_inode(dentry);
+	dfid = v9fs_parent_fid(dentry);
+	if (IS_ERR(dfid)) {
+		retval = PTR_ERR(dfid);
+		p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", retval);
+		return retval;
+	}
+	if (v9fs_proto_dotl(v9ses))
+		retval = p9_client_unlinkat(dfid, dentry->d_name.name,
+					    v9fs_at_to_dotl_flags(flags));
+	p9_fid_put(dfid);
+	if (retval == -EOPNOTSUPP) {
+		/* Try the one based on path */
+		v9fid = v9fs_fid_clone(dentry);
+		if (IS_ERR(v9fid))
+			return PTR_ERR(v9fid);
+		retval = p9_client_remove(v9fid);
+	}
+	if (!retval) {
+		/*
+		 * directories on unlink should have zero
+		 * link count
+		 */
+		if (flags & AT_REMOVEDIR) {
+			clear_nlink(inode);
+			v9fs_dec_count(dir);
+		} else
+			v9fs_dec_count(inode);
+
+		v9fs_invalidate_inode_attr(inode);
+		v9fs_invalidate_inode_attr(dir);
+
+		/* invalidate all fids associated with dentry */
+		/* NOTE: This will not include open fids */
+		v9fs_dentry_fid_remove(dentry);
+	}
+	return retval;
+}
+
+/**
+ * v9fs_create - Create a file
+ * @v9ses: session information
+ * @dir: directory that dentry is being created in
+ * @dentry:  dentry that is being created
+ * @extension: 9p2000.u extension string to support devices, etc.
+ * @perm: create permissions
+ * @mode: open mode
+ *
+ */
+static struct p9_fid *
+v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
+		struct dentry *dentry, char *extension, u32 perm, u8 mode)
+{
+	int err;
+	const unsigned char *name;
+	struct p9_fid *dfid, *ofid = NULL, *fid = NULL;
+	struct inode *inode;
+
+	p9_debug(P9_DEBUG_VFS, "name %pd\n", dentry);
+
+	name = dentry->d_name.name;
+	dfid = v9fs_parent_fid(dentry);
+	if (IS_ERR(dfid)) {
+		err = PTR_ERR(dfid);
+		p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", err);
+		return ERR_PTR(err);
+	}
+
+	/* clone a fid to use for creation */
+	ofid = clone_fid(dfid);
+	if (IS_ERR(ofid)) {
+		err = PTR_ERR(ofid);
+		p9_debug(P9_DEBUG_VFS, "p9_client_walk failed %d\n", err);
+		goto error;
+	}
+
+	err = p9_client_fcreate(ofid, name, perm, mode, extension);
+	if (err < 0) {
+		p9_debug(P9_DEBUG_VFS, "p9_client_fcreate failed %d\n", err);
+		goto error;
+	}
+
+	if (!(perm & P9_DMLINK)) {
+		/* now walk from the parent so we can get unopened fid */
+		fid = p9_client_walk(dfid, 1, &name, 1);
+		if (IS_ERR(fid)) {
+			err = PTR_ERR(fid);
+			p9_debug(P9_DEBUG_VFS,
+				   "p9_client_walk failed %d\n", err);
+			goto error;
+		}
+		/*
+		 * instantiate inode and assign the unopened fid to the dentry
+		 */
+		inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
+		if (IS_ERR(inode)) {
+			err = PTR_ERR(inode);
+			p9_debug(P9_DEBUG_VFS,
+				   "inode creation failed %d\n", err);
+			goto error;
+		}
+		v9fs_fid_add(dentry, &fid);
+		d_instantiate(dentry, inode);
+	}
+	p9_fid_put(dfid);
+	return ofid;
+error:
+	p9_fid_put(dfid);
+	p9_fid_put(ofid);
+	p9_fid_put(fid);
+	return ERR_PTR(err);
+}
+
+/**
+ * v9fs_vfs_create - VFS hook to create a regular file
+ * @idmap: idmap of the mount
+ * @dir: The parent directory
+ * @dentry: The name of file to be created
+ * @mode: The UNIX file mode to set
+ *
+ * open(.., O_CREAT) is handled in v9fs_vfs_atomic_open().  This is only called
+ * for mknod(2).
+ *
+ */
+
+static int
+v9fs_vfs_create(struct mnt_idmap *idmap, struct inode *dir,
+		struct dentry *dentry, umode_t mode)
+{
+	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
+	u32 perm = unixmode2p9mode(v9ses, mode);
+	struct p9_fid *fid;
+
+	/* P9_OEXCL? */
+	fid = v9fs_create(v9ses, dir, dentry, NULL, perm, P9_ORDWR);
+	if (IS_ERR(fid))
+		return PTR_ERR(fid);
+
+	v9fs_invalidate_inode_attr(dir);
+	p9_fid_put(fid);
+
+	return 0;
+}
+
+/**
+ * v9fs_vfs_mkdir - VFS mkdir hook to create a directory
+ * @idmap: idmap of the mount
+ * @dir:  inode that is being unlinked
+ * @dentry: dentry that is being unlinked
+ * @mode: mode for new directory
+ *
+ */
+
+static struct dentry *v9fs_vfs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
+				     struct dentry *dentry, umode_t mode)
+{
+	u32 perm;
+	struct p9_fid *fid;
+	struct v9fs_session_info *v9ses;
+
+	p9_debug(P9_DEBUG_VFS, "name %pd\n", dentry);
+	v9ses = v9fs_inode2v9ses(dir);
+	perm = unixmode2p9mode(v9ses, mode);
+	fid = v9fs_create(v9ses, dir, dentry, NULL, perm, P9_OREAD);
+	if (IS_ERR(fid))
+		return ERR_CAST(fid);
+	inc_nlink(dir);
+	v9fs_invalidate_inode_attr(dir);
+	p9_fid_put(fid);
+	return NULL;
+}
+
+/**
+ * v9fs_vfs_lookup - VFS lookup hook to "walk" to a new inode
+ * @dir:  inode that is being walked from
+ * @dentry: dentry that is being walked to?
+ * @flags: lookup flags (unused)
+ *
+ */
+
+struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
+				      unsigned int flags)
+{
+	struct dentry *res;
+	struct v9fs_session_info *v9ses;
+	struct p9_fid *dfid, *fid;
+	struct inode *inode;
+	const unsigned char *name;
+
+	p9_debug(P9_DEBUG_VFS, "dir: %p dentry: (%pd) %p flags: %x\n",
+		 dir, dentry, dentry, flags);
+
+	if (dentry->d_name.len > NAME_MAX)
+		return ERR_PTR(-ENAMETOOLONG);
+
+	v9ses = v9fs_inode2v9ses(dir);
+	/* We can walk d_parent because we hold the dir->i_mutex */
+	dfid = v9fs_parent_fid(dentry);
+	if (IS_ERR(dfid))
+		return ERR_CAST(dfid);
+
+	/*
+	 * Make sure we don't use a wrong inode due to parallel
+	 * unlink. For cached mode create calls request for new
+	 * inode. But with cache disabled, lookup should do this.
+	 */
+	name = dentry->d_name.name;
+	fid = p9_client_walk(dfid, 1, &name, 1);
+	p9_fid_put(dfid);
+	if (fid == ERR_PTR(-ENOENT)) {
+		inode = NULL;
+		v9fs_ndentry_refresh_timeout(dentry);
+	} else if (IS_ERR(fid)) {
+		inode = ERR_CAST(fid);
+	} else if (v9ses->cache & (CACHE_META|CACHE_LOOSE)) {
+		inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
+	} else {
+		inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
+	}
+	/*
+	 * If we had a rename on the server and a parallel lookup
+	 * for the new name, then make sure we instantiate with
+	 * the new name. ie look up for a/b, while on server somebody
+	 * moved b under k and client parallely did a lookup for
+	 * k/b.
+	 */
+	res = d_splice_alias(inode, dentry);
+	if (!IS_ERR(fid)) {
+		if (!res)
+			v9fs_fid_add(dentry, &fid);
+		else if (!IS_ERR(res))
+			v9fs_fid_add(res, &fid);
+		else
+			p9_fid_put(fid);
+	}
+	return res;
+}
+
+static int
+v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
+		     struct file *file, unsigned int flags, umode_t mode)
+{
+	int err;
+	u32 perm;
+	struct v9fs_inode __maybe_unused *v9inode;
+	struct v9fs_session_info *v9ses;
+	struct p9_fid *fid;
+	struct inode *inode;
+	int p9_omode;
+
+	if (d_in_lookup(dentry)) {
+		struct dentry *res = v9fs_vfs_lookup(dir, dentry, 0);
+		if (res || d_really_is_positive(dentry))
+			return finish_no_open(file, res);
+	}
+
+	/* Only creates */
+	if (!(flags & O_CREAT))
+		return finish_no_open(file, NULL);
+
+	v9ses = v9fs_inode2v9ses(dir);
+	perm = unixmode2p9mode(v9ses, mode);
+	p9_omode = v9fs_uflags2omode(flags, v9fs_proto_dotu(v9ses));
+
+	if ((v9ses->cache & CACHE_WRITEBACK) && (p9_omode & P9_OWRITE)) {
+		p9_omode = (p9_omode & ~(P9_OWRITE | P9_OAPPEND)) | P9_ORDWR;
+		p9_debug(P9_DEBUG_CACHE,
+			"write-only file with writeback enabled, creating w/ O_RDWR\n");
+	}
+	fid = v9fs_create(v9ses, dir, dentry, NULL, perm, p9_omode);
+	if (IS_ERR(fid))
+		return PTR_ERR(fid);
+
+	v9fs_invalidate_inode_attr(dir);
+	inode = d_inode(dentry);
+	v9inode = V9FS_I(inode);
+	err = finish_open(file, dentry, generic_file_open);
+	if (unlikely(err)) {
+		p9_fid_put(fid);
+		return err;
+	}
+
+	file->private_data = fid;
+#ifdef CONFIG_9P_FSCACHE
+	if (v9ses->cache & CACHE_FSCACHE)
+		fscache_use_cookie(v9fs_inode_cookie(v9inode),
+				   file->f_mode & FMODE_WRITE);
+#endif
+
+	v9fs_fid_add_modes(fid, v9ses->flags, v9ses->cache, file->f_flags);
+	v9fs_open_fid_add(inode, &fid);
+
+	file->f_mode |= FMODE_CREATED;
+	return 0;
+}
+
+/**
+ * v9fs_vfs_unlink - VFS unlink hook to delete an inode
+ * @i:  inode that is being unlinked
+ * @d: dentry that is being unlinked
+ *
+ */
+
+int v9fs_vfs_unlink(struct inode *i, struct dentry *d)
+{
+	return v9fs_remove(i, d, 0);
+}
+
+/**
+ * v9fs_vfs_rmdir - VFS unlink hook to delete a directory
+ * @i:  inode that is being unlinked
+ * @d: dentry that is being unlinked
+ *
+ */
+
+int v9fs_vfs_rmdir(struct inode *i, struct dentry *d)
+{
+	return v9fs_remove(i, d, AT_REMOVEDIR);
+}
+
+/**
+ * v9fs_vfs_rename - VFS hook to rename an inode
+ * @idmap: The idmap of the mount
+ * @old_dir:  old dir inode
+ * @old_dentry: old dentry
+ * @new_dir: new dir inode
+ * @new_dentry: new dentry
+ * @flags: RENAME_* flags
+ *
+ */
+
+int
+v9fs_vfs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
+		struct dentry *old_dentry, struct inode *new_dir,
+		struct dentry *new_dentry, unsigned int flags)
+{
+	int retval;
+	struct inode *old_inode;
+	struct inode *new_inode;
+	struct v9fs_session_info *v9ses;
+	struct p9_fid *oldfid = NULL, *dfid = NULL;
+	struct p9_fid *olddirfid = NULL;
+	struct p9_fid *newdirfid = NULL;
+	struct p9_wstat wstat;
+
+	if (flags)
+		return -EINVAL;
+
+	p9_debug(P9_DEBUG_VFS, "\n");
+	old_inode = d_inode(old_dentry);
+	new_inode = d_inode(new_dentry);
+	v9ses = v9fs_inode2v9ses(old_inode);
+	oldfid = v9fs_fid_lookup(old_dentry);
+	if (IS_ERR(oldfid))
+		return PTR_ERR(oldfid);
+
+	dfid = v9fs_parent_fid(old_dentry);
+	olddirfid = clone_fid(dfid);
+	p9_fid_put(dfid);
+	dfid = NULL;
+
+	if (IS_ERR(olddirfid)) {
+		retval = PTR_ERR(olddirfid);
+		goto error;
+	}
+
+	dfid = v9fs_parent_fid(new_dentry);
+	newdirfid = clone_fid(dfid);
+	p9_fid_put(dfid);
+	dfid = NULL;
+
+	if (IS_ERR(newdirfid)) {
+		retval = PTR_ERR(newdirfid);
+		goto error;
+	}
+
+	down_write(&v9ses->rename_sem);
+	if (v9fs_proto_dotl(v9ses)) {
+		retval = p9_client_renameat(olddirfid, old_dentry->d_name.name,
+					    newdirfid, new_dentry->d_name.name);
+		if (retval == -EOPNOTSUPP)
+			retval = p9_client_rename(oldfid, newdirfid,
+						  new_dentry->d_name.name);
+		if (retval != -EOPNOTSUPP)
+			goto error_locked;
+	}
+	if (old_dentry->d_parent != new_dentry->d_parent) {
+		/*
+		 * 9P .u can only handle file rename in the same directory
+		 */
+
+		p9_debug(P9_DEBUG_ERROR, "old dir and new dir are different\n");
+		retval = -EXDEV;
+		goto error_locked;
+	}
+	v9fs_blank_wstat(&wstat);
+	wstat.muid = v9ses->uname;
+	wstat.name = new_dentry->d_name.name;
+	retval = p9_client_wstat(oldfid, &wstat);
+
+error_locked:
+	if (!retval) {
+		if (new_inode) {
+			if (S_ISDIR(new_inode->i_mode))
+				clear_nlink(new_inode);
+			else
+				v9fs_dec_count(new_inode);
+		}
+		if (S_ISDIR(old_inode->i_mode)) {
+			if (!new_inode)
+				inc_nlink(new_dir);
+			v9fs_dec_count(old_dir);
+		}
+		v9fs_invalidate_inode_attr(old_inode);
+		v9fs_invalidate_inode_attr(old_dir);
+		v9fs_invalidate_inode_attr(new_dir);
+
+		/* successful rename */
+		d_move(old_dentry, new_dentry);
+	}
+	up_write(&v9ses->rename_sem);
+
+error:
+	p9_fid_put(newdirfid);
+	p9_fid_put(olddirfid);
+	p9_fid_put(oldfid);
+	return retval;
+}
+
+/**
+ * v9fs_vfs_getattr - retrieve file metadata
+ * @idmap: idmap of the mount
+ * @path: Object to query
+ * @stat: metadata structure to populate
+ * @request_mask: Mask of STATX_xxx flags indicating the caller's interests
+ * @flags: AT_STATX_xxx setting
+ *
+ */
+
+static int
+v9fs_vfs_getattr(struct mnt_idmap *idmap, const struct path *path,
+		 struct kstat *stat, u32 request_mask, unsigned int flags)
+{
+	struct dentry *dentry = path->dentry;
+	struct inode *inode = d_inode(dentry);
+	struct v9fs_session_info *v9ses;
+	struct p9_fid *fid;
+	struct p9_wstat *st;
+
+	p9_debug(P9_DEBUG_VFS, "dentry: %p\n", dentry);
+	v9ses = v9fs_dentry2v9ses(dentry);
+	if (v9ses->cache & (CACHE_META|CACHE_LOOSE)) {
+		generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
+		return 0;
+	} else if (v9ses->cache & CACHE_WRITEBACK) {
+		if (S_ISREG(inode->i_mode)) {
+			int retval = filemap_fdatawrite(inode->i_mapping);
+
+			if (retval)
+				p9_debug(P9_DEBUG_ERROR,
+				    "flushing writeback during getattr returned %d\n", retval);
+		}
+	}
+	fid = v9fs_fid_lookup(dentry);
+	if (IS_ERR(fid))
+		return PTR_ERR(fid);
+
+	st = p9_client_stat(fid);
+	p9_fid_put(fid);
+	if (IS_ERR(st))
+		return PTR_ERR(st);
+
+	v9fs_stat2inode(st, d_inode(dentry), dentry->d_sb, 0);
+	generic_fillattr(&nop_mnt_idmap, request_mask, d_inode(dentry), stat);
+
+	p9stat_free(st);
+	kfree(st);
+	return 0;
+}
+
+/**
+ * v9fs_vfs_setattr - set file metadata
+ * @idmap: idmap of the mount
+ * @dentry: file whose metadata to set
+ * @iattr: metadata assignment structure
+ *
+ */
+
+static int v9fs_vfs_setattr(struct mnt_idmap *idmap,
+			    struct dentry *dentry, struct iattr *iattr)
+{
+	int retval, use_dentry = 0;
+	struct inode *inode = d_inode(dentry);
+	struct v9fs_session_info *v9ses;
+	struct p9_fid *fid = NULL;
+	struct p9_wstat wstat;
+
+	p9_debug(P9_DEBUG_VFS, "\n");
+	retval = setattr_prepare(&nop_mnt_idmap, dentry, iattr);
+	if (retval)
+		return retval;
+
+	v9ses = v9fs_dentry2v9ses(dentry);
+	if (iattr->ia_valid & ATTR_FILE) {
+		fid = iattr->ia_file->private_data;
+		WARN_ON(!fid);
+	}
+	if (!fid) {
+		fid = v9fs_fid_lookup(dentry);
+		use_dentry = 1;
+	}
+	if (IS_ERR(fid))
+		return PTR_ERR(fid);
+
+	v9fs_blank_wstat(&wstat);
+	if (iattr->ia_valid & ATTR_MODE)
+		wstat.mode = unixmode2p9mode(v9ses, iattr->ia_mode);
+
+	if (iattr->ia_valid & ATTR_MTIME)
+		wstat.mtime = iattr->ia_mtime.tv_sec;
+
+	if (iattr->ia_valid & ATTR_ATIME)
+		wstat.atime = iattr->ia_atime.tv_sec;
+
+	if (iattr->ia_valid & ATTR_SIZE)
+		wstat.length = iattr->ia_size;
+
+	if (v9fs_proto_dotu(v9ses)) {
+		if (iattr->ia_valid & ATTR_UID)
+			wstat.n_uid = iattr->ia_uid;
+
+		if (iattr->ia_valid & ATTR_GID)
+			wstat.n_gid = iattr->ia_gid;
+	}
+
+	/* Write all dirty data */
+	if (d_is_reg(dentry)) {
+		retval = filemap_fdatawrite(inode->i_mapping);
+		if (retval)
+			p9_debug(P9_DEBUG_ERROR,
+			    "flushing writeback during setattr returned %d\n", retval);
+	}
+
+	retval = p9_client_wstat(fid, &wstat);
+
+	if (use_dentry)
+		p9_fid_put(fid);
+
+	if (retval < 0)
+		return retval;
+
+	if ((iattr->ia_valid & ATTR_SIZE) &&
+		 iattr->ia_size != i_size_read(inode)) {
+		truncate_setsize(inode, iattr->ia_size);
+		netfs_resize_file(netfs_inode(inode), iattr->ia_size, true);
+
+#ifdef CONFIG_9P_FSCACHE
+		if (v9ses->cache & CACHE_FSCACHE) {
+			struct v9fs_inode *v9inode = V9FS_I(inode);
+
+			fscache_resize_cookie(v9fs_inode_cookie(v9inode), iattr->ia_size);
+		}
+#endif
+	}
+
+	v9fs_invalidate_inode_attr(inode);
+
+	setattr_copy(&nop_mnt_idmap, inode, iattr);
+	mark_inode_dirty(inode);
+	return 0;
+}
+
+/**
+ * v9fs_stat2inode - populate an inode structure with mistat info
+ * @stat: Plan 9 metadata (mistat) structure
+ * @inode: inode to populate
+ * @sb: superblock of filesystem
+ * @flags: control flags (e.g. V9FS_STAT2INODE_KEEP_ISIZE)
+ *
+ */
+
+void
+v9fs_stat2inode(struct p9_wstat *stat, struct inode *inode,
+		 struct super_block *sb, unsigned int flags)
+{
+	umode_t mode;
+	struct v9fs_session_info *v9ses = sb->s_fs_info;
+	struct v9fs_inode *v9inode = V9FS_I(inode);
+
+	inode_set_atime(inode, stat->atime, 0);
+	inode_set_mtime(inode, stat->mtime, 0);
+	inode_set_ctime(inode, stat->mtime, 0);
+
+	inode->i_uid = v9ses->dfltuid;
+	inode->i_gid = v9ses->dfltgid;
+
+	if (v9fs_proto_dotu(v9ses)) {
+		inode->i_uid = stat->n_uid;
+		inode->i_gid = stat->n_gid;
+	}
+	if ((S_ISREG(inode->i_mode)) || (S_ISDIR(inode->i_mode))) {
+		if (v9fs_proto_dotu(v9ses)) {
+			unsigned int i_nlink;
+			/*
+			 * Hadlink support got added later to the .u extension.
+			 * So there can be a server out there that doesn't
+			 * support this even with .u extension. That would
+			 * just leave us with stat->extension being an empty
+			 * string, though.
+			 */
+			/* HARDLINKCOUNT %u */
+			if (sscanf(stat->extension,
+				   " HARDLINKCOUNT %u", &i_nlink) == 1)
+				set_nlink(inode, i_nlink);
+		}
+	}
+	mode = p9mode2perm(v9ses, stat);
+	mode |= inode->i_mode & ~S_IALLUGO;
+	inode->i_mode = mode;
+
+	spin_lock(&inode->i_lock);
+	netfs_write_remote_i_size(inode, stat->length);
+	if (!(flags & V9FS_STAT2INODE_KEEP_ISIZE))
+		i_size_write(inode, stat->length);
+	/* not real number of blocks, but 512 byte ones ... */
+	inode->i_blocks = (stat->length + 512 - 1) >> 9;
+	spin_unlock(&inode->i_lock);
+	v9inode->cache_validity &= ~V9FS_INO_INVALID_ATTR;
+}
+
+/**
+ * v9fs_vfs_get_link - follow a symlink path
+ * @dentry: dentry for symlink
+ * @inode: inode for symlink
+ * @done: delayed call for when we are done with the return value
+ */
+
+static const char *v9fs_vfs_get_link(struct dentry *dentry,
+				     struct inode *inode,
+				     struct delayed_call *done)
+{
+	struct v9fs_session_info *v9ses;
+	struct p9_fid *fid;
+	struct p9_wstat *st;
+	char *res;
+
+	if (!dentry)
+		return ERR_PTR(-ECHILD);
+
+	v9ses = v9fs_dentry2v9ses(dentry);
+	if (!v9fs_proto_dotu(v9ses))
+		return ERR_PTR(-EBADF);
+
+	p9_debug(P9_DEBUG_VFS, "%pd\n", dentry);
+	fid = v9fs_fid_lookup(dentry);
+
+	if (IS_ERR(fid))
+		return ERR_CAST(fid);
+
+	st = p9_client_stat(fid);
+	p9_fid_put(fid);
+	if (IS_ERR(st))
+		return ERR_CAST(st);
+
+	if (!(st->mode & P9_DMSYMLINK)) {
+		p9stat_free(st);
+		kfree(st);
+		return ERR_PTR(-EINVAL);
+	}
+	res = st->extension;
+	st->extension = NULL;
+	if (strlen(res) >= PATH_MAX)
+		res[PATH_MAX - 1] = '\0';
+
+	p9stat_free(st);
+	kfree(st);
+	set_delayed_call(done, kfree_link, res);
+	return res;
+}
+
+/**
+ * v9fs_vfs_mkspecial - create a special file
+ * @dir: inode to create special file in
+ * @dentry: dentry to create
+ * @perm: mode to create special file
+ * @extension: 9p2000.u format extension string representing special file
+ *
+ */
+
+static int v9fs_vfs_mkspecial(struct inode *dir, struct dentry *dentry,
+	u32 perm, const char *extension)
+{
+	struct p9_fid *fid;
+	struct v9fs_session_info *v9ses;
+
+	v9ses = v9fs_inode2v9ses(dir);
+	if (!v9fs_proto_dotu(v9ses)) {
+		p9_debug(P9_DEBUG_ERROR, "not extended\n");
+		return -EPERM;
+	}
+
+	fid = v9fs_create(v9ses, dir, dentry, (char *) extension, perm,
+								P9_OREAD);
+	if (IS_ERR(fid))
+		return PTR_ERR(fid);
+
+	v9fs_invalidate_inode_attr(dir);
+	p9_fid_put(fid);
+	return 0;
+}
+
+/**
+ * v9fs_vfs_symlink - helper function to create symlinks
+ * @idmap: idmap of the mount
+ * @dir: directory inode containing symlink
+ * @dentry: dentry for symlink
+ * @symname: symlink data
+ *
+ * See Also: 9P2000.u RFC for more information
+ *
+ */
+
+static int
+v9fs_vfs_symlink(struct mnt_idmap *idmap, struct inode *dir,
+		 struct dentry *dentry, const char *symname)
+{
+	p9_debug(P9_DEBUG_VFS, " %llu,%pd,%s\n",
+		 dir->i_ino, dentry, symname);
+
+	return v9fs_vfs_mkspecial(dir, dentry, P9_DMSYMLINK, symname);
+}
+
+#define U32_MAX_DIGITS 10
+
+/**
+ * v9fs_vfs_link - create a hardlink
+ * @old_dentry: dentry for file to link to
+ * @dir: inode destination for new link
+ * @dentry: dentry for link
+ *
+ */
+
+static int
+v9fs_vfs_link(struct dentry *old_dentry, struct inode *dir,
+	      struct dentry *dentry)
+{
+	int retval;
+	char name[1 + U32_MAX_DIGITS + 2]; /* sign + number + \n + \0 */
+	struct p9_fid *oldfid;
+
+	p9_debug(P9_DEBUG_VFS, " %llu,%pd,%pd\n",
+		 dir->i_ino, dentry, old_dentry);
+
+	oldfid = v9fs_fid_clone(old_dentry);
+	if (IS_ERR(oldfid))
+		return PTR_ERR(oldfid);
+
+	sprintf(name, "%d\n", oldfid->fid);
+	retval = v9fs_vfs_mkspecial(dir, dentry, P9_DMLINK, name);
+	if (!retval) {
+		v9fs_refresh_inode(oldfid, d_inode(old_dentry));
+		v9fs_invalidate_inode_attr(dir);
+	}
+	p9_fid_put(oldfid);
+	return retval;
+}
+
+/**
+ * v9fs_vfs_mknod - create a special file
+ * @idmap: idmap of the mount
+ * @dir: inode destination for new link
+ * @dentry: dentry for file
+ * @mode: mode for creation
+ * @rdev: device associated with special file
+ *
+ */
+
+static int
+v9fs_vfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
+	       struct dentry *dentry, umode_t mode, dev_t rdev)
+{
+	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
+	int retval;
+	char name[2 + U32_MAX_DIGITS + 1 + U32_MAX_DIGITS + 1];
+	u32 perm;
+
+	p9_debug(P9_DEBUG_VFS, " %llu,%pd mode: %x MAJOR: %u MINOR: %u\n",
+		 dir->i_ino, dentry, mode,
+		 MAJOR(rdev), MINOR(rdev));
+
+	/* build extension */
+	if (S_ISBLK(mode))
+		sprintf(name, "b %u %u", MAJOR(rdev), MINOR(rdev));
+	else if (S_ISCHR(mode))
+		sprintf(name, "c %u %u", MAJOR(rdev), MINOR(rdev));
+	else
+		*name = 0;
+
+	perm = unixmode2p9mode(v9ses, mode);
+	retval = v9fs_vfs_mkspecial(dir, dentry, perm, name);
+
+	return retval;
+}
+
+int v9fs_refresh_inode(struct p9_fid *fid, struct inode *inode)
+{
+	int umode;
+	dev_t rdev;
+	struct p9_wstat *st;
+	struct v9fs_session_info *v9ses;
+	unsigned int flags;
+
+	v9ses = v9fs_inode2v9ses(inode);
+	st = p9_client_stat(fid);
+	if (IS_ERR(st))
+		return PTR_ERR(st);
+	/*
+	 * Don't update inode if the file type is different
+	 */
+	umode = p9mode2unixmode(v9ses, st, &rdev);
+	if (inode_wrong_type(inode, umode))
+		goto out;
+
+	/*
+	 * We don't want to refresh inode->i_size,
+	 * because we may have cached data
+	 */
+	flags = (v9ses->cache & CACHE_LOOSE) ?
+		V9FS_STAT2INODE_KEEP_ISIZE : 0;
+	v9fs_stat2inode(st, inode, inode->i_sb, flags);
+out:
+	p9stat_free(st);
+	kfree(st);
+	return 0;
+}
+
+static const struct inode_operations v9fs_dir_inode_operations_dotu = {
+	.create = v9fs_vfs_create,
+	.lookup = v9fs_vfs_lookup,
+	.atomic_open = v9fs_vfs_atomic_open,
+	.symlink = v9fs_vfs_symlink,
+	.link = v9fs_vfs_link,
+	.unlink = v9fs_vfs_unlink,
+	.mkdir = v9fs_vfs_mkdir,
+	.rmdir = v9fs_vfs_rmdir,
+	.mknod = v9fs_vfs_mknod,
+	.rename = v9fs_vfs_rename,
+	.getattr = v9fs_vfs_getattr,
+	.setattr = v9fs_vfs_setattr,
+};
+
+static const struct inode_operations v9fs_dir_inode_operations = {
+	.create = v9fs_vfs_create,
+	.lookup = v9fs_vfs_lookup,
+	.atomic_open = v9fs_vfs_atomic_open,
+	.unlink = v9fs_vfs_unlink,
+	.mkdir = v9fs_vfs_mkdir,
+	.rmdir = v9fs_vfs_rmdir,
+	.mknod = v9fs_vfs_mknod,
+	.rename = v9fs_vfs_rename,
+	.getattr = v9fs_vfs_getattr,
+	.setattr = v9fs_vfs_setattr,
+};
+
+static const struct inode_operations v9fs_file_inode_operations = {
+	.getattr = v9fs_vfs_getattr,
+	.setattr = v9fs_vfs_setattr,
+};
+
+static const struct inode_operations v9fs_symlink_inode_operations = {
+	.get_link = v9fs_vfs_get_link,
+	.getattr = v9fs_vfs_getattr,
+	.setattr = v9fs_vfs_setattr,
+};