Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1931 insertions, 0 deletions

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
new file mode 100644
index 000000000..6098e0c7f
--- /dev/null
+++ b/fs/fuse/dir.c
@@ -0,0 +1,1931 @@
+/*
+  FUSE: Filesystem in Userspace
+  Copyright (C) 2001-2008  Miklos Szeredi <miklos@szeredi.hu>
+
+  This program can be distributed under the terms of the GNU GPL.
+  See the file COPYING.
+*/
+
+#include "fuse_i.h"
+
+#include <linux/pagemap.h>
+#include <linux/file.h>
+#include <linux/sched.h>
+#include <linux/namei.h>
+#include <linux/slab.h>
+#include <linux/xattr.h>
+#include <linux/posix_acl.h>
+
+static bool fuse_use_readdirplus(struct inode *dir, struct dir_context *ctx)
+{
+	struct fuse_conn *fc = get_fuse_conn(dir);
+	struct fuse_inode *fi = get_fuse_inode(dir);
+
+	if (!fc->do_readdirplus)
+		return false;
+	if (!fc->readdirplus_auto)
+		return true;
+	if (test_and_clear_bit(FUSE_I_ADVISE_RDPLUS, &fi->state))
+		return true;
+	if (ctx->pos == 0)
+		return true;
+	return false;
+}
+
+static void fuse_advise_use_readdirplus(struct inode *dir)
+{
+	struct fuse_inode *fi = get_fuse_inode(dir);
+
+	set_bit(FUSE_I_ADVISE_RDPLUS, &fi->state);
+}
+
+union fuse_dentry {
+	u64 time;
+	struct rcu_head rcu;
+};
+
+static inline void fuse_dentry_settime(struct dentry *entry, u64 time)
+{
+	((union fuse_dentry *) entry->d_fsdata)->time = time;
+}
+
+static inline u64 fuse_dentry_time(struct dentry *entry)
+{
+	return ((union fuse_dentry *) entry->d_fsdata)->time;
+}
+
+/*
+ * FUSE caches dentries and attributes with separate timeout.  The
+ * time in jiffies until the dentry/attributes are valid is stored in
+ * dentry->d_fsdata and fuse_inode->i_time respectively.
+ */
+
+/*
+ * Calculate the time in jiffies until a dentry/attributes are valid
+ */
+static u64 time_to_jiffies(u64 sec, u32 nsec)
+{
+	if (sec || nsec) {
+		struct timespec64 ts = {
+			sec,
+			min_t(u32, nsec, NSEC_PER_SEC - 1)
+		};
+
+		return get_jiffies_64() + timespec64_to_jiffies(&ts);
+	} else
+		return 0;
+}
+
+/*
+ * Set dentry and possibly attribute timeouts from the lookup/mk*
+ * replies
+ */
+static void fuse_change_entry_timeout(struct dentry *entry,
+				      struct fuse_entry_out *o)
+{
+	fuse_dentry_settime(entry,
+		time_to_jiffies(o->entry_valid, o->entry_valid_nsec));
+}
+
+static u64 attr_timeout(struct fuse_attr_out *o)
+{
+	return time_to_jiffies(o->attr_valid, o->attr_valid_nsec);
+}
+
+static u64 entry_attr_timeout(struct fuse_entry_out *o)
+{
+	return time_to_jiffies(o->attr_valid, o->attr_valid_nsec);
+}
+
+/*
+ * Mark the attributes as stale, so that at the next call to
+ * ->getattr() they will be fetched from userspace
+ */
+void fuse_invalidate_attr(struct inode *inode)
+{
+	get_fuse_inode(inode)->i_time = 0;
+}
+
+/**
+ * Mark the attributes as stale due to an atime change.  Avoid the invalidate if
+ * atime is not used.
+ */
+void fuse_invalidate_atime(struct inode *inode)
+{
+	if (!IS_RDONLY(inode))
+		fuse_invalidate_attr(inode);
+}
+
+/*
+ * Just mark the entry as stale, so that a next attempt to look it up
+ * will result in a new lookup call to userspace
+ *
+ * This is called when a dentry is about to become negative and the
+ * timeout is unknown (unlink, rmdir, rename and in some cases
+ * lookup)
+ */
+void fuse_invalidate_entry_cache(struct dentry *entry)
+{
+	fuse_dentry_settime(entry, 0);
+}
+
+/*
+ * Same as fuse_invalidate_entry_cache(), but also try to remove the
+ * dentry from the hash
+ */
+static void fuse_invalidate_entry(struct dentry *entry)
+{
+	d_invalidate(entry);
+	fuse_invalidate_entry_cache(entry);
+}
+
+static void fuse_lookup_init(struct fuse_conn *fc, struct fuse_args *args,
+			     u64 nodeid, const struct qstr *name,
+			     struct fuse_entry_out *outarg)
+{
+	memset(outarg, 0, sizeof(struct fuse_entry_out));
+	args->in.h.opcode = FUSE_LOOKUP;
+	args->in.h.nodeid = nodeid;
+	args->in.numargs = 1;
+	args->in.args[0].size = name->len + 1;
+	args->in.args[0].value = name->name;
+	args->out.numargs = 1;
+	args->out.args[0].size = sizeof(struct fuse_entry_out);
+	args->out.args[0].value = outarg;
+}
+
+u64 fuse_get_attr_version(struct fuse_conn *fc)
+{
+	u64 curr_version;
+
+	/*
+	 * The spin lock isn't actually needed on 64bit archs, but we
+	 * don't yet care too much about such optimizations.
+	 */
+	spin_lock(&fc->lock);
+	curr_version = fc->attr_version;
+	spin_unlock(&fc->lock);
+
+	return curr_version;
+}
+
+/*
+ * Check whether the dentry is still valid
+ *
+ * If the entry validity timeout has expired and the dentry is
+ * positive, try to redo the lookup.  If the lookup results in a
+ * different inode, then let the VFS invalidate the dentry and redo
+ * the lookup once more.  If the lookup results in the same inode,
+ * then refresh the attributes, timeouts and mark the dentry valid.
+ */
+static int fuse_dentry_revalidate(struct dentry *entry, unsigned int flags)
+{
+	struct inode *inode;
+	struct dentry *parent;
+	struct fuse_conn *fc;
+	struct fuse_inode *fi;
+	int ret;
+
+	inode = d_inode_rcu(entry);
+	if (inode && fuse_is_bad(inode))
+		goto invalid;
+	else if (time_before64(fuse_dentry_time(entry), get_jiffies_64()) ||
+		 (flags & LOOKUP_REVAL)) {
+		struct fuse_entry_out outarg;
+		FUSE_ARGS(args);
+		struct fuse_forget_link *forget;
+		u64 attr_version;
+
+		/* For negative dentries, always do a fresh lookup */
+		if (!inode)
+			goto invalid;
+
+		ret = -ECHILD;
+		if (flags & LOOKUP_RCU)
+			goto out;
+
+		fc = get_fuse_conn(inode);
+
+		forget = fuse_alloc_forget();
+		ret = -ENOMEM;
+		if (!forget)
+			goto out;
+
+		attr_version = fuse_get_attr_version(fc);
+
+		parent = dget_parent(entry);
+		fuse_lookup_init(fc, &args, get_node_id(d_inode(parent)),
+				 &entry->d_name, &outarg);
+		ret = fuse_simple_request(fc, &args);
+		dput(parent);
+		/* Zero nodeid is same as -ENOENT */
+		if (!ret && !outarg.nodeid)
+			ret = -ENOENT;
+		if (!ret) {
+			fi = get_fuse_inode(inode);
+			if (outarg.nodeid != get_node_id(inode)) {
+				fuse_queue_forget(fc, forget, outarg.nodeid, 1);
+				goto invalid;
+			}
+			spin_lock(&fc->lock);
+			fi->nlookup++;
+			spin_unlock(&fc->lock);
+		}
+		kfree(forget);
+		if (ret == -ENOMEM)
+			goto out;
+		if (ret || fuse_invalid_attr(&outarg.attr) ||
+		    (outarg.attr.mode ^ inode->i_mode) & S_IFMT)
+			goto invalid;
+
+		forget_all_cached_acls(inode);
+		fuse_change_attributes(inode, &outarg.attr,
+				       entry_attr_timeout(&outarg),
+				       attr_version);
+		fuse_change_entry_timeout(entry, &outarg);
+	} else if (inode) {
+		fi = get_fuse_inode(inode);
+		if (flags & LOOKUP_RCU) {
+			if (test_bit(FUSE_I_INIT_RDPLUS, &fi->state))
+				return -ECHILD;
+		} else if (test_and_clear_bit(FUSE_I_INIT_RDPLUS, &fi->state)) {
+			parent = dget_parent(entry);
+			fuse_advise_use_readdirplus(d_inode(parent));
+			dput(parent);
+		}
+	}
+	ret = 1;
+out:
+	return ret;
+
+invalid:
+	ret = 0;
+	goto out;
+}
+
+static int invalid_nodeid(u64 nodeid)
+{
+	return !nodeid || nodeid == FUSE_ROOT_ID;
+}
+
+static int fuse_dentry_init(struct dentry *dentry)
+{
+	dentry->d_fsdata = kzalloc(sizeof(union fuse_dentry), GFP_KERNEL);
+
+	return dentry->d_fsdata ? 0 : -ENOMEM;
+}
+static void fuse_dentry_release(struct dentry *dentry)
+{
+	union fuse_dentry *fd = dentry->d_fsdata;
+
+	kfree_rcu(fd, rcu);
+}
+
+const struct dentry_operations fuse_dentry_operations = {
+	.d_revalidate	= fuse_dentry_revalidate,
+	.d_init		= fuse_dentry_init,
+	.d_release	= fuse_dentry_release,
+};
+
+const struct dentry_operations fuse_root_dentry_operations = {
+	.d_init		= fuse_dentry_init,
+	.d_release	= fuse_dentry_release,
+};
+
+int fuse_valid_type(int m)
+{
+	return S_ISREG(m) || S_ISDIR(m) || S_ISLNK(m) || S_ISCHR(m) ||
+		S_ISBLK(m) || S_ISFIFO(m) || S_ISSOCK(m);
+}
+
+bool fuse_invalid_attr(struct fuse_attr *attr)
+{
+	return !fuse_valid_type(attr->mode) ||
+		attr->size > LLONG_MAX;
+}
+
+int fuse_lookup_name(struct super_block *sb, u64 nodeid, const struct qstr *name,
+		     struct fuse_entry_out *outarg, struct inode **inode)
+{
+	struct fuse_conn *fc = get_fuse_conn_super(sb);
+	FUSE_ARGS(args);
+	struct fuse_forget_link *forget;
+	u64 attr_version;
+	int err;
+
+	*inode = NULL;
+	err = -ENAMETOOLONG;
+	if (name->len > FUSE_NAME_MAX)
+		goto out;
+
+
+	forget = fuse_alloc_forget();
+	err = -ENOMEM;
+	if (!forget)
+		goto out;
+
+	attr_version = fuse_get_attr_version(fc);
+
+	fuse_lookup_init(fc, &args, nodeid, name, outarg);
+	err = fuse_simple_request(fc, &args);
+	/* Zero nodeid is same as -ENOENT, but with valid timeout */
+	if (err || !outarg->nodeid)
+		goto out_put_forget;
+
+	err = -EIO;
+	if (!outarg->nodeid)
+		goto out_put_forget;
+	if (fuse_invalid_attr(&outarg->attr))
+		goto out_put_forget;
+
+	*inode = fuse_iget(sb, outarg->nodeid, outarg->generation,
+			   &outarg->attr, entry_attr_timeout(outarg),
+			   attr_version);
+	err = -ENOMEM;
+	if (!*inode) {
+		fuse_queue_forget(fc, forget, outarg->nodeid, 1);
+		goto out;
+	}
+	err = 0;
+
+ out_put_forget:
+	kfree(forget);
+ out:
+	return err;
+}
+
+static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry,
+				  unsigned int flags)
+{
+	int err;
+	struct fuse_entry_out outarg;
+	struct inode *inode;
+	struct dentry *newent;
+	bool outarg_valid = true;
+	bool locked;
+
+	if (fuse_is_bad(dir))
+		return ERR_PTR(-EIO);
+
+	locked = fuse_lock_inode(dir);
+	err = fuse_lookup_name(dir->i_sb, get_node_id(dir), &entry->d_name,
+			       &outarg, &inode);
+	fuse_unlock_inode(dir, locked);
+	if (err == -ENOENT) {
+		outarg_valid = false;
+		err = 0;
+	}
+	if (err)
+		goto out_err;
+
+	err = -EIO;
+	if (inode && get_node_id(inode) == FUSE_ROOT_ID)
+		goto out_iput;
+
+	newent = d_splice_alias(inode, entry);
+	err = PTR_ERR(newent);
+	if (IS_ERR(newent))
+		goto out_err;
+
+	entry = newent ? newent : entry;
+	if (outarg_valid)
+		fuse_change_entry_timeout(entry, &outarg);
+	else
+		fuse_invalidate_entry_cache(entry);
+
+	fuse_advise_use_readdirplus(dir);
+	return newent;
+
+ out_iput:
+	iput(inode);
+ out_err:
+	return ERR_PTR(err);
+}
+
+/*
+ * Atomic create+open operation
+ *
+ * If the filesystem doesn't support this, then fall back to separate
+ * 'mknod' + 'open' requests.
+ */
+static int fuse_create_open(struct inode *dir, struct dentry *entry,
+			    struct file *file, unsigned flags,
+			    umode_t mode)
+{
+	int err;
+	struct inode *inode;
+	struct fuse_conn *fc = get_fuse_conn(dir);
+	FUSE_ARGS(args);
+	struct fuse_forget_link *forget;
+	struct fuse_create_in inarg;
+	struct fuse_open_out outopen;
+	struct fuse_entry_out outentry;
+	struct fuse_file *ff;
+
+	/* Userspace expects S_IFREG in create mode */
+	BUG_ON((mode & S_IFMT) != S_IFREG);
+
+	forget = fuse_alloc_forget();
+	err = -ENOMEM;
+	if (!forget)
+		goto out_err;
+
+	err = -ENOMEM;
+	ff = fuse_file_alloc(fc);
+	if (!ff)
+		goto out_put_forget_req;
+
+	if (!fc->dont_mask)
+		mode &= ~current_umask();
+
+	flags &= ~O_NOCTTY;
+	memset(&inarg, 0, sizeof(inarg));
+	memset(&outentry, 0, sizeof(outentry));
+	inarg.flags = flags;
+	inarg.mode = mode;
+	inarg.umask = current_umask();
+	args.in.h.opcode = FUSE_CREATE;
+	args.in.h.nodeid = get_node_id(dir);
+	args.in.numargs = 2;
+	args.in.args[0].size = sizeof(inarg);
+	args.in.args[0].value = &inarg;
+	args.in.args[1].size = entry->d_name.len + 1;
+	args.in.args[1].value = entry->d_name.name;
+	args.out.numargs = 2;
+	args.out.args[0].size = sizeof(outentry);
+	args.out.args[0].value = &outentry;
+	args.out.args[1].size = sizeof(outopen);
+	args.out.args[1].value = &outopen;
+	err = fuse_simple_request(fc, &args);
+	if (err)
+		goto out_free_ff;
+
+	err = -EIO;
+	if (!S_ISREG(outentry.attr.mode) || invalid_nodeid(outentry.nodeid) ||
+	    fuse_invalid_attr(&outentry.attr))
+		goto out_free_ff;
+
+	ff->fh = outopen.fh;
+	ff->nodeid = outentry.nodeid;
+	ff->open_flags = outopen.open_flags;
+	inode = fuse_iget(dir->i_sb, outentry.nodeid, outentry.generation,
+			  &outentry.attr, entry_attr_timeout(&outentry), 0);
+	if (!inode) {
+		flags &= ~(O_CREAT | O_EXCL | O_TRUNC);
+		fuse_sync_release(ff, flags);
+		fuse_queue_forget(fc, forget, outentry.nodeid, 1);
+		err = -ENOMEM;
+		goto out_err;
+	}
+	kfree(forget);
+	d_instantiate(entry, inode);
+	fuse_change_entry_timeout(entry, &outentry);
+	fuse_invalidate_attr(dir);
+	err = finish_open(file, entry, generic_file_open);
+	if (err) {
+		fuse_sync_release(ff, flags);
+	} else {
+		file->private_data = ff;
+		fuse_finish_open(inode, file);
+	}
+	return err;
+
+out_free_ff:
+	fuse_file_free(ff);
+out_put_forget_req:
+	kfree(forget);
+out_err:
+	return err;
+}
+
+static int fuse_mknod(struct inode *, struct dentry *, umode_t, dev_t);
+static int fuse_atomic_open(struct inode *dir, struct dentry *entry,
+			    struct file *file, unsigned flags,
+			    umode_t mode)
+{
+	int err;
+	struct fuse_conn *fc = get_fuse_conn(dir);
+	struct dentry *res = NULL;
+
+	if (fuse_is_bad(dir))
+		return -EIO;
+
+	if (d_in_lookup(entry)) {
+		res = fuse_lookup(dir, entry, 0);
+		if (IS_ERR(res))
+			return PTR_ERR(res);
+
+		if (res)
+			entry = res;
+	}
+
+	if (!(flags & O_CREAT) || d_really_is_positive(entry))
+		goto no_open;
+
+	/* Only creates */
+	file->f_mode |= FMODE_CREATED;
+
+	if (fc->no_create)
+		goto mknod;
+
+	err = fuse_create_open(dir, entry, file, flags, mode);
+	if (err == -ENOSYS) {
+		fc->no_create = 1;
+		goto mknod;
+	}
+out_dput:
+	dput(res);
+	return err;
+
+mknod:
+	err = fuse_mknod(dir, entry, mode, 0);
+	if (err)
+		goto out_dput;
+no_open:
+	return finish_no_open(file, res);
+}
+
+/*
+ * Code shared between mknod, mkdir, symlink and link
+ */
+static int create_new_entry(struct fuse_conn *fc, struct fuse_args *args,
+			    struct inode *dir, struct dentry *entry,
+			    umode_t mode)
+{
+	struct fuse_entry_out outarg;
+	struct inode *inode;
+	struct dentry *d;
+	int err;
+	struct fuse_forget_link *forget;
+
+	if (fuse_is_bad(dir))
+		return -EIO;
+
+	forget = fuse_alloc_forget();
+	if (!forget)
+		return -ENOMEM;
+
+	memset(&outarg, 0, sizeof(outarg));
+	args->in.h.nodeid = get_node_id(dir);
+	args->out.numargs = 1;
+	args->out.args[0].size = sizeof(outarg);
+	args->out.args[0].value = &outarg;
+	err = fuse_simple_request(fc, args);
+	if (err)
+		goto out_put_forget_req;
+
+	err = -EIO;
+	if (invalid_nodeid(outarg.nodeid) || fuse_invalid_attr(&outarg.attr))
+		goto out_put_forget_req;
+
+	if ((outarg.attr.mode ^ mode) & S_IFMT)
+		goto out_put_forget_req;
+
+	inode = fuse_iget(dir->i_sb, outarg.nodeid, outarg.generation,
+			  &outarg.attr, entry_attr_timeout(&outarg), 0);
+	if (!inode) {
+		fuse_queue_forget(fc, forget, outarg.nodeid, 1);
+		return -ENOMEM;
+	}
+	kfree(forget);
+
+	d_drop(entry);
+	d = d_splice_alias(inode, entry);
+	if (IS_ERR(d))
+		return PTR_ERR(d);
+
+	if (d) {
+		fuse_change_entry_timeout(d, &outarg);
+		dput(d);
+	} else {
+		fuse_change_entry_timeout(entry, &outarg);
+	}
+	fuse_invalidate_attr(dir);
+	return 0;
+
+ out_put_forget_req:
+	kfree(forget);
+	return err;
+}
+
+static int fuse_mknod(struct inode *dir, struct dentry *entry, umode_t mode,
+		      dev_t rdev)
+{
+	struct fuse_mknod_in inarg;
+	struct fuse_conn *fc = get_fuse_conn(dir);
+	FUSE_ARGS(args);
+
+	if (!fc->dont_mask)
+		mode &= ~current_umask();
+
+	memset(&inarg, 0, sizeof(inarg));
+	inarg.mode = mode;
+	inarg.rdev = new_encode_dev(rdev);
+	inarg.umask = current_umask();
+	args.in.h.opcode = FUSE_MKNOD;
+	args.in.numargs = 2;
+	args.in.args[0].size = sizeof(inarg);
+	args.in.args[0].value = &inarg;
+	args.in.args[1].size = entry->d_name.len + 1;
+	args.in.args[1].value = entry->d_name.name;
+	return create_new_entry(fc, &args, dir, entry, mode);
+}
+
+static int fuse_create(struct inode *dir, struct dentry *entry, umode_t mode,
+		       bool excl)
+{
+	return fuse_mknod(dir, entry, mode, 0);
+}
+
+static int fuse_mkdir(struct inode *dir, struct dentry *entry, umode_t mode)
+{
+	struct fuse_mkdir_in inarg;
+	struct fuse_conn *fc = get_fuse_conn(dir);
+	FUSE_ARGS(args);
+
+	if (!fc->dont_mask)
+		mode &= ~current_umask();
+
+	memset(&inarg, 0, sizeof(inarg));
+	inarg.mode = mode;
+	inarg.umask = current_umask();
+	args.in.h.opcode = FUSE_MKDIR;
+	args.in.numargs = 2;
+	args.in.args[0].size = sizeof(inarg);
+	args.in.args[0].value = &inarg;
+	args.in.args[1].size = entry->d_name.len + 1;
+	args.in.args[1].value = entry->d_name.name;
+	return create_new_entry(fc, &args, dir, entry, S_IFDIR);
+}
+
+static int fuse_symlink(struct inode *dir, struct dentry *entry,
+			const char *link)
+{
+	struct fuse_conn *fc = get_fuse_conn(dir);
+	unsigned len = strlen(link) + 1;
+	FUSE_ARGS(args);
+
+	args.in.h.opcode = FUSE_SYMLINK;
+	args.in.numargs = 2;
+	args.in.args[0].size = entry->d_name.len + 1;
+	args.in.args[0].value = entry->d_name.name;
+	args.in.args[1].size = len;
+	args.in.args[1].value = link;
+	return create_new_entry(fc, &args, dir, entry, S_IFLNK);
+}
+
+void fuse_update_ctime(struct inode *inode)
+{
+	if (!IS_NOCMTIME(inode)) {
+		inode->i_ctime = current_time(inode);
+		mark_inode_dirty_sync(inode);
+	}
+}
+
+static int fuse_unlink(struct inode *dir, struct dentry *entry)
+{
+	int err;
+	struct fuse_conn *fc = get_fuse_conn(dir);
+	FUSE_ARGS(args);
+
+	if (fuse_is_bad(dir))
+		return -EIO;
+
+	args.in.h.opcode = FUSE_UNLINK;
+	args.in.h.nodeid = get_node_id(dir);
+	args.in.numargs = 1;
+	args.in.args[0].size = entry->d_name.len + 1;
+	args.in.args[0].value = entry->d_name.name;
+	err = fuse_simple_request(fc, &args);
+	if (!err) {
+		struct inode *inode = d_inode(entry);
+		struct fuse_inode *fi = get_fuse_inode(inode);
+
+		spin_lock(&fc->lock);
+		fi->attr_version = ++fc->attr_version;
+		/*
+		 * If i_nlink == 0 then unlink doesn't make sense, yet this can
+		 * happen if userspace filesystem is careless.  It would be
+		 * difficult to enforce correct nlink usage so just ignore this
+		 * condition here
+		 */
+		if (inode->i_nlink > 0)
+			drop_nlink(inode);
+		spin_unlock(&fc->lock);
+		fuse_invalidate_attr(inode);
+		fuse_invalidate_attr(dir);
+		fuse_invalidate_entry_cache(entry);
+		fuse_update_ctime(inode);
+	} else if (err == -EINTR)
+		fuse_invalidate_entry(entry);
+	return err;
+}
+
+static int fuse_rmdir(struct inode *dir, struct dentry *entry)
+{
+	int err;
+	struct fuse_conn *fc = get_fuse_conn(dir);
+	FUSE_ARGS(args);
+
+	if (fuse_is_bad(dir))
+		return -EIO;
+
+	args.in.h.opcode = FUSE_RMDIR;
+	args.in.h.nodeid = get_node_id(dir);
+	args.in.numargs = 1;
+	args.in.args[0].size = entry->d_name.len + 1;
+	args.in.args[0].value = entry->d_name.name;
+	err = fuse_simple_request(fc, &args);
+	if (!err) {
+		clear_nlink(d_inode(entry));
+		fuse_invalidate_attr(dir);
+		fuse_invalidate_entry_cache(entry);
+	} else if (err == -EINTR)
+		fuse_invalidate_entry(entry);
+	return err;
+}
+
+static int fuse_rename_common(struct inode *olddir, struct dentry *oldent,
+			      struct inode *newdir, struct dentry *newent,
+			      unsigned int flags, int opcode, size_t argsize)
+{
+	int err;
+	struct fuse_rename2_in inarg;
+	struct fuse_conn *fc = get_fuse_conn(olddir);
+	FUSE_ARGS(args);
+
+	memset(&inarg, 0, argsize);
+	inarg.newdir = get_node_id(newdir);
+	inarg.flags = flags;
+	args.in.h.opcode = opcode;
+	args.in.h.nodeid = get_node_id(olddir);
+	args.in.numargs = 3;
+	args.in.args[0].size = argsize;
+	args.in.args[0].value = &inarg;
+	args.in.args[1].size = oldent->d_name.len + 1;
+	args.in.args[1].value = oldent->d_name.name;
+	args.in.args[2].size = newent->d_name.len + 1;
+	args.in.args[2].value = newent->d_name.name;
+	err = fuse_simple_request(fc, &args);
+	if (!err) {
+		/* ctime changes */
+		fuse_invalidate_attr(d_inode(oldent));
+		fuse_update_ctime(d_inode(oldent));
+
+		if (flags & RENAME_EXCHANGE) {
+			fuse_invalidate_attr(d_inode(newent));
+			fuse_update_ctime(d_inode(newent));
+		}
+
+		fuse_invalidate_attr(olddir);
+		if (olddir != newdir)
+			fuse_invalidate_attr(newdir);
+
+		/* newent will end up negative */
+		if (!(flags & RENAME_EXCHANGE) && d_really_is_positive(newent)) {
+			fuse_invalidate_attr(d_inode(newent));
+			fuse_invalidate_entry_cache(newent);
+			fuse_update_ctime(d_inode(newent));
+		}
+	} else if (err == -EINTR) {
+		/* If request was interrupted, DEITY only knows if the
+		   rename actually took place.  If the invalidation
+		   fails (e.g. some process has CWD under the renamed
+		   directory), then there can be inconsistency between
+		   the dcache and the real filesystem.  Tough luck. */
+		fuse_invalidate_entry(oldent);
+		if (d_really_is_positive(newent))
+			fuse_invalidate_entry(newent);
+	}
+
+	return err;
+}
+
+static int fuse_rename2(struct inode *olddir, struct dentry *oldent,
+			struct inode *newdir, struct dentry *newent,
+			unsigned int flags)
+{
+	struct fuse_conn *fc = get_fuse_conn(olddir);
+	int err;
+
+	if (fuse_is_bad(olddir))
+		return -EIO;
+
+	if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
+		return -EINVAL;
+
+	if (flags) {
+		if (fc->no_rename2 || fc->minor < 23)
+			return -EINVAL;
+
+		err = fuse_rename_common(olddir, oldent, newdir, newent, flags,
+					 FUSE_RENAME2,
+					 sizeof(struct fuse_rename2_in));
+		if (err == -ENOSYS) {
+			fc->no_rename2 = 1;
+			err = -EINVAL;
+		}
+	} else {
+		err = fuse_rename_common(olddir, oldent, newdir, newent, 0,
+					 FUSE_RENAME,
+					 sizeof(struct fuse_rename_in));
+	}
+
+	return err;
+}
+
+static int fuse_link(struct dentry *entry, struct inode *newdir,
+		     struct dentry *newent)
+{
+	int err;
+	struct fuse_link_in inarg;
+	struct inode *inode = d_inode(entry);
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	FUSE_ARGS(args);
+
+	memset(&inarg, 0, sizeof(inarg));
+	inarg.oldnodeid = get_node_id(inode);
+	args.in.h.opcode = FUSE_LINK;
+	args.in.numargs = 2;
+	args.in.args[0].size = sizeof(inarg);
+	args.in.args[0].value = &inarg;
+	args.in.args[1].size = newent->d_name.len + 1;
+	args.in.args[1].value = newent->d_name.name;
+	err = create_new_entry(fc, &args, newdir, newent, inode->i_mode);
+	/* Contrary to "normal" filesystems it can happen that link
+	   makes two "logical" inodes point to the same "physical"
+	   inode.  We invalidate the attributes of the old one, so it
+	   will reflect changes in the backing inode (link count,
+	   etc.)
+	*/
+	if (!err) {
+		struct fuse_inode *fi = get_fuse_inode(inode);
+
+		spin_lock(&fc->lock);
+		fi->attr_version = ++fc->attr_version;
+		if (likely(inode->i_nlink < UINT_MAX))
+			inc_nlink(inode);
+		spin_unlock(&fc->lock);
+		fuse_invalidate_attr(inode);
+		fuse_update_ctime(inode);
+	} else if (err == -EINTR) {
+		fuse_invalidate_attr(inode);
+	}
+	return err;
+}
+
+static void fuse_fillattr(struct inode *inode, struct fuse_attr *attr,
+			  struct kstat *stat)
+{
+	unsigned int blkbits;
+	struct fuse_conn *fc = get_fuse_conn(inode);
+
+	/* see the comment in fuse_change_attributes() */
+	if (fc->writeback_cache && S_ISREG(inode->i_mode)) {
+		attr->size = i_size_read(inode);
+		attr->mtime = inode->i_mtime.tv_sec;
+		attr->mtimensec = inode->i_mtime.tv_nsec;
+		attr->ctime = inode->i_ctime.tv_sec;
+		attr->ctimensec = inode->i_ctime.tv_nsec;
+	}
+
+	stat->dev = inode->i_sb->s_dev;
+	stat->ino = attr->ino;
+	stat->mode = (inode->i_mode & S_IFMT) | (attr->mode & 07777);
+	stat->nlink = attr->nlink;
+	stat->uid = make_kuid(fc->user_ns, attr->uid);
+	stat->gid = make_kgid(fc->user_ns, attr->gid);
+	stat->rdev = inode->i_rdev;
+	stat->atime.tv_sec = attr->atime;
+	stat->atime.tv_nsec = attr->atimensec;
+	stat->mtime.tv_sec = attr->mtime;
+	stat->mtime.tv_nsec = attr->mtimensec;
+	stat->ctime.tv_sec = attr->ctime;
+	stat->ctime.tv_nsec = attr->ctimensec;
+	stat->size = attr->size;
+	stat->blocks = attr->blocks;
+
+	if (attr->blksize != 0)
+		blkbits = ilog2(attr->blksize);
+	else
+		blkbits = inode->i_sb->s_blocksize_bits;
+
+	stat->blksize = 1 << blkbits;
+}
+
+static int fuse_do_getattr(struct inode *inode, struct kstat *stat,
+			   struct file *file)
+{
+	int err;
+	struct fuse_getattr_in inarg;
+	struct fuse_attr_out outarg;
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	FUSE_ARGS(args);
+	u64 attr_version;
+
+	attr_version = fuse_get_attr_version(fc);
+
+	memset(&inarg, 0, sizeof(inarg));
+	memset(&outarg, 0, sizeof(outarg));
+	/* Directories have separate file-handle space */
+	if (file && S_ISREG(inode->i_mode)) {
+		struct fuse_file *ff = file->private_data;
+
+		inarg.getattr_flags |= FUSE_GETATTR_FH;
+		inarg.fh = ff->fh;
+	}
+	args.in.h.opcode = FUSE_GETATTR;
+	args.in.h.nodeid = get_node_id(inode);
+	args.in.numargs = 1;
+	args.in.args[0].size = sizeof(inarg);
+	args.in.args[0].value = &inarg;
+	args.out.numargs = 1;
+	args.out.args[0].size = sizeof(outarg);
+	args.out.args[0].value = &outarg;
+	err = fuse_simple_request(fc, &args);
+	if (!err) {
+		if (fuse_invalid_attr(&outarg.attr) ||
+		    (inode->i_mode ^ outarg.attr.mode) & S_IFMT) {
+			fuse_make_bad(inode);
+			err = -EIO;
+		} else {
+			fuse_change_attributes(inode, &outarg.attr,
+					       attr_timeout(&outarg),
+					       attr_version);
+			if (stat)
+				fuse_fillattr(inode, &outarg.attr, stat);
+		}
+	}
+	return err;
+}
+
+static int fuse_update_get_attr(struct inode *inode, struct file *file,
+				struct kstat *stat, unsigned int flags)
+{
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	int err = 0;
+	bool sync;
+
+	if (flags & AT_STATX_FORCE_SYNC)
+		sync = true;
+	else if (flags & AT_STATX_DONT_SYNC)
+		sync = false;
+	else
+		sync = time_before64(fi->i_time, get_jiffies_64());
+
+	if (sync) {
+		forget_all_cached_acls(inode);
+		err = fuse_do_getattr(inode, stat, file);
+	} else if (stat) {
+		generic_fillattr(inode, stat);
+		stat->mode = fi->orig_i_mode;
+		stat->ino = fi->orig_ino;
+	}
+
+	return err;
+}
+
+int fuse_update_attributes(struct inode *inode, struct file *file)
+{
+	return fuse_update_get_attr(inode, file, NULL, 0);
+}
+
+int fuse_reverse_inval_entry(struct super_block *sb, u64 parent_nodeid,
+			     u64 child_nodeid, struct qstr *name)
+{
+	int err = -ENOTDIR;
+	struct inode *parent;
+	struct dentry *dir;
+	struct dentry *entry;
+
+	parent = ilookup5(sb, parent_nodeid, fuse_inode_eq, &parent_nodeid);
+	if (!parent)
+		return -ENOENT;
+
+	inode_lock_nested(parent, I_MUTEX_PARENT);
+	if (!S_ISDIR(parent->i_mode))
+		goto unlock;
+
+	err = -ENOENT;
+	dir = d_find_alias(parent);
+	if (!dir)
+		goto unlock;
+
+	name->hash = full_name_hash(dir, name->name, name->len);
+	entry = d_lookup(dir, name);
+	dput(dir);
+	if (!entry)
+		goto unlock;
+
+	fuse_invalidate_attr(parent);
+	fuse_invalidate_entry(entry);
+
+	if (child_nodeid != 0 && d_really_is_positive(entry)) {
+		inode_lock(d_inode(entry));
+		if (get_node_id(d_inode(entry)) != child_nodeid) {
+			err = -ENOENT;
+			goto badentry;
+		}
+		if (d_mountpoint(entry)) {
+			err = -EBUSY;
+			goto badentry;
+		}
+		if (d_is_dir(entry)) {
+			shrink_dcache_parent(entry);
+			if (!simple_empty(entry)) {
+				err = -ENOTEMPTY;
+				goto badentry;
+			}
+			d_inode(entry)->i_flags |= S_DEAD;
+		}
+		dont_mount(entry);
+		clear_nlink(d_inode(entry));
+		err = 0;
+ badentry:
+		inode_unlock(d_inode(entry));
+		if (!err)
+			d_delete(entry);
+	} else {
+		err = 0;
+	}
+	dput(entry);
+
+ unlock:
+	inode_unlock(parent);
+	iput(parent);
+	return err;
+}
+
+/*
+ * Calling into a user-controlled filesystem gives the filesystem
+ * daemon ptrace-like capabilities over the current process.  This
+ * means, that the filesystem daemon is able to record the exact
+ * filesystem operations performed, and can also control the behavior
+ * of the requester process in otherwise impossible ways.  For example
+ * it can delay the operation for arbitrary length of time allowing
+ * DoS against the requester.
+ *
+ * For this reason only those processes can call into the filesystem,
+ * for which the owner of the mount has ptrace privilege.  This
+ * excludes processes started by other users, suid or sgid processes.
+ */
+int fuse_allow_current_process(struct fuse_conn *fc)
+{
+	const struct cred *cred;
+
+	if (fc->allow_other)
+		return current_in_userns(fc->user_ns);
+
+	cred = current_cred();
+	if (uid_eq(cred->euid, fc->user_id) &&
+	    uid_eq(cred->suid, fc->user_id) &&
+	    uid_eq(cred->uid,  fc->user_id) &&
+	    gid_eq(cred->egid, fc->group_id) &&
+	    gid_eq(cred->sgid, fc->group_id) &&
+	    gid_eq(cred->gid,  fc->group_id))
+		return 1;
+
+	return 0;
+}
+
+static int fuse_access(struct inode *inode, int mask)
+{
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	FUSE_ARGS(args);
+	struct fuse_access_in inarg;
+	int err;
+
+	BUG_ON(mask & MAY_NOT_BLOCK);
+
+	if (fc->no_access)
+		return 0;
+
+	memset(&inarg, 0, sizeof(inarg));
+	inarg.mask = mask & (MAY_READ | MAY_WRITE | MAY_EXEC);
+	args.in.h.opcode = FUSE_ACCESS;
+	args.in.h.nodeid = get_node_id(inode);
+	args.in.numargs = 1;
+	args.in.args[0].size = sizeof(inarg);
+	args.in.args[0].value = &inarg;
+	err = fuse_simple_request(fc, &args);
+	if (err == -ENOSYS) {
+		fc->no_access = 1;
+		err = 0;
+	}
+	return err;
+}
+
+static int fuse_perm_getattr(struct inode *inode, int mask)
+{
+	if (mask & MAY_NOT_BLOCK)
+		return -ECHILD;
+
+	forget_all_cached_acls(inode);
+	return fuse_do_getattr(inode, NULL, NULL);
+}
+
+/*
+ * Check permission.  The two basic access models of FUSE are:
+ *
+ * 1) Local access checking ('default_permissions' mount option) based
+ * on file mode.  This is the plain old disk filesystem permission
+ * modell.
+ *
+ * 2) "Remote" access checking, where server is responsible for
+ * checking permission in each inode operation.  An exception to this
+ * is if ->permission() was invoked from sys_access() in which case an
+ * access request is sent.  Execute permission is still checked
+ * locally based on file mode.
+ */
+static int fuse_permission(struct inode *inode, int mask)
+{
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	bool refreshed = false;
+	int err = 0;
+
+	if (fuse_is_bad(inode))
+		return -EIO;
+
+	if (!fuse_allow_current_process(fc))
+		return -EACCES;
+
+	/*
+	 * If attributes are needed, refresh them before proceeding
+	 */
+	if (fc->default_permissions ||
+	    ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))) {
+		struct fuse_inode *fi = get_fuse_inode(inode);
+
+		if (time_before64(fi->i_time, get_jiffies_64())) {
+			refreshed = true;
+
+			err = fuse_perm_getattr(inode, mask);
+			if (err)
+				return err;
+		}
+	}
+
+	if (fc->default_permissions) {
+		err = generic_permission(inode, mask);
+
+		/* If permission is denied, try to refresh file
+		   attributes.  This is also needed, because the root
+		   node will at first have no permissions */
+		if (err == -EACCES && !refreshed) {
+			err = fuse_perm_getattr(inode, mask);
+			if (!err)
+				err = generic_permission(inode, mask);
+		}
+
+		/* Note: the opposite of the above test does not
+		   exist.  So if permissions are revoked this won't be
+		   noticed immediately, only after the attribute
+		   timeout has expired */
+	} else if (mask & (MAY_ACCESS | MAY_CHDIR)) {
+		err = fuse_access(inode, mask);
+	} else if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) {
+		if (!(inode->i_mode & S_IXUGO)) {
+			if (refreshed)
+				return -EACCES;
+
+			err = fuse_perm_getattr(inode, mask);
+			if (!err && !(inode->i_mode & S_IXUGO))
+				return -EACCES;
+		}
+	}
+	return err;
+}
+
+static int parse_dirfile(char *buf, size_t nbytes, struct file *file,
+			 struct dir_context *ctx)
+{
+	while (nbytes >= FUSE_NAME_OFFSET) {
+		struct fuse_dirent *dirent = (struct fuse_dirent *) buf;
+		size_t reclen = FUSE_DIRENT_SIZE(dirent);
+		if (!dirent->namelen || dirent->namelen > FUSE_NAME_MAX)
+			return -EIO;
+		if (reclen > nbytes)
+			break;
+		if (memchr(dirent->name, '/', dirent->namelen) != NULL)
+			return -EIO;
+
+		if (!dir_emit(ctx, dirent->name, dirent->namelen,
+			       dirent->ino, dirent->type))
+			break;
+
+		buf += reclen;
+		nbytes -= reclen;
+		ctx->pos = dirent->off;
+	}
+
+	return 0;
+}
+
+static int fuse_direntplus_link(struct file *file,
+				struct fuse_direntplus *direntplus,
+				u64 attr_version)
+{
+	struct fuse_entry_out *o = &direntplus->entry_out;
+	struct fuse_dirent *dirent = &direntplus->dirent;
+	struct dentry *parent = file->f_path.dentry;
+	struct qstr name = QSTR_INIT(dirent->name, dirent->namelen);
+	struct dentry *dentry;
+	struct dentry *alias;
+	struct inode *dir = d_inode(parent);
+	struct fuse_conn *fc;
+	struct inode *inode;
+	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
+
+	if (!o->nodeid) {
+		/*
+		 * Unlike in the case of fuse_lookup, zero nodeid does not mean
+		 * ENOENT. Instead, it only means the userspace filesystem did
+		 * not want to return attributes/handle for this entry.
+		 *
+		 * So do nothing.
+		 */
+		return 0;
+	}
+
+	if (name.name[0] == '.') {
+		/*
+		 * We could potentially refresh the attributes of the directory
+		 * and its parent?
+		 */
+		if (name.len == 1)
+			return 0;
+		if (name.name[1] == '.' && name.len == 2)
+			return 0;
+	}
+
+	if (invalid_nodeid(o->nodeid))
+		return -EIO;
+	if (fuse_invalid_attr(&o->attr))
+		return -EIO;
+
+	fc = get_fuse_conn(dir);
+
+	name.hash = full_name_hash(parent, name.name, name.len);
+	dentry = d_lookup(parent, &name);
+	if (!dentry) {
+retry:
+		dentry = d_alloc_parallel(parent, &name, &wq);
+		if (IS_ERR(dentry))
+			return PTR_ERR(dentry);
+	}
+	if (!d_in_lookup(dentry)) {
+		struct fuse_inode *fi;
+		inode = d_inode(dentry);
+		if (!inode ||
+		    get_node_id(inode) != o->nodeid ||
+		    ((o->attr.mode ^ inode->i_mode) & S_IFMT)) {
+			d_invalidate(dentry);
+			dput(dentry);
+			goto retry;
+		}
+		if (fuse_is_bad(inode)) {
+			dput(dentry);
+			return -EIO;
+		}
+
+		fi = get_fuse_inode(inode);
+		spin_lock(&fc->lock);
+		fi->nlookup++;
+		spin_unlock(&fc->lock);
+
+		forget_all_cached_acls(inode);
+		fuse_change_attributes(inode, &o->attr,
+				       entry_attr_timeout(o),
+				       attr_version);
+		/*
+		 * The other branch comes via fuse_iget()
+		 * which bumps nlookup inside
+		 */
+	} else {
+		inode = fuse_iget(dir->i_sb, o->nodeid, o->generation,
+				  &o->attr, entry_attr_timeout(o),
+				  attr_version);
+		if (!inode)
+			inode = ERR_PTR(-ENOMEM);
+
+		alias = d_splice_alias(inode, dentry);
+		d_lookup_done(dentry);
+		if (alias) {
+			dput(dentry);
+			dentry = alias;
+		}
+		if (IS_ERR(dentry))
+			return PTR_ERR(dentry);
+	}
+	if (fc->readdirplus_auto)
+		set_bit(FUSE_I_INIT_RDPLUS, &get_fuse_inode(inode)->state);
+	fuse_change_entry_timeout(dentry, o);
+
+	dput(dentry);
+	return 0;
+}
+
+static int parse_dirplusfile(char *buf, size_t nbytes, struct file *file,
+			     struct dir_context *ctx, u64 attr_version)
+{
+	struct fuse_direntplus *direntplus;
+	struct fuse_dirent *dirent;
+	size_t reclen;
+	int over = 0;
+	int ret;
+
+	while (nbytes >= FUSE_NAME_OFFSET_DIRENTPLUS) {
+		direntplus = (struct fuse_direntplus *) buf;
+		dirent = &direntplus->dirent;
+		reclen = FUSE_DIRENTPLUS_SIZE(direntplus);
+
+		if (!dirent->namelen || dirent->namelen > FUSE_NAME_MAX)
+			return -EIO;
+		if (reclen > nbytes)
+			break;
+		if (memchr(dirent->name, '/', dirent->namelen) != NULL)
+			return -EIO;
+
+		if (!over) {
+			/* We fill entries into dstbuf only as much as
+			   it can hold. But we still continue iterating
+			   over remaining entries to link them. If not,
+			   we need to send a FORGET for each of those
+			   which we did not link.
+			*/
+			over = !dir_emit(ctx, dirent->name, dirent->namelen,
+				       dirent->ino, dirent->type);
+			if (!over)
+				ctx->pos = dirent->off;
+		}
+
+		buf += reclen;
+		nbytes -= reclen;
+
+		ret = fuse_direntplus_link(file, direntplus, attr_version);
+		if (ret)
+			fuse_force_forget(file, direntplus->entry_out.nodeid);
+	}
+
+	return 0;
+}
+
+static int fuse_readdir(struct file *file, struct dir_context *ctx)
+{
+	int plus, err;
+	size_t nbytes;
+	struct page *page;
+	struct inode *inode = file_inode(file);
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	struct fuse_req *req;
+	u64 attr_version = 0;
+	bool locked;
+
+	if (fuse_is_bad(inode))
+		return -EIO;
+
+	req = fuse_get_req(fc, 1);
+	if (IS_ERR(req))
+		return PTR_ERR(req);
+
+	page = alloc_page(GFP_KERNEL);
+	if (!page) {
+		fuse_put_request(fc, req);
+		return -ENOMEM;
+	}
+
+	plus = fuse_use_readdirplus(inode, ctx);
+	req->out.argpages = 1;
+	req->num_pages = 1;
+	req->pages[0] = page;
+	req->page_descs[0].length = PAGE_SIZE;
+	if (plus) {
+		attr_version = fuse_get_attr_version(fc);
+		fuse_read_fill(req, file, ctx->pos, PAGE_SIZE,
+			       FUSE_READDIRPLUS);
+	} else {
+		fuse_read_fill(req, file, ctx->pos, PAGE_SIZE,
+			       FUSE_READDIR);
+	}
+	locked = fuse_lock_inode(inode);
+	fuse_request_send(fc, req);
+	fuse_unlock_inode(inode, locked);
+	nbytes = req->out.args[0].size;
+	err = req->out.h.error;
+	fuse_put_request(fc, req);
+	if (!err) {
+		if (plus) {
+			err = parse_dirplusfile(page_address(page), nbytes,
+						file, ctx,
+						attr_version);
+		} else {
+			err = parse_dirfile(page_address(page), nbytes, file,
+					    ctx);
+		}
+	}
+
+	__free_page(page);
+	fuse_invalidate_atime(inode);
+	return err;
+}
+
+static const char *fuse_get_link(struct dentry *dentry,
+				 struct inode *inode,
+				 struct delayed_call *done)
+{
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	FUSE_ARGS(args);
+	char *link;
+	ssize_t ret;
+
+	if (!dentry)
+		return ERR_PTR(-ECHILD);
+
+	if (fuse_is_bad(inode))
+		return ERR_PTR(-EIO);
+
+	link = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!link)
+		return ERR_PTR(-ENOMEM);
+
+	args.in.h.opcode = FUSE_READLINK;
+	args.in.h.nodeid = get_node_id(inode);
+	args.out.argvar = 1;
+	args.out.numargs = 1;
+	args.out.args[0].size = PAGE_SIZE - 1;
+	args.out.args[0].value = link;
+	ret = fuse_simple_request(fc, &args);
+	if (ret < 0) {
+		kfree(link);
+		link = ERR_PTR(ret);
+	} else {
+		link[ret] = '\0';
+		set_delayed_call(done, kfree_link, link);
+	}
+	fuse_invalidate_atime(inode);
+	return link;
+}
+
+static int fuse_dir_open(struct inode *inode, struct file *file)
+{
+	return fuse_open_common(inode, file, true);
+}
+
+static int fuse_dir_release(struct inode *inode, struct file *file)
+{
+	fuse_release_common(file, true);
+
+	return 0;
+}
+
+static int fuse_dir_fsync(struct file *file, loff_t start, loff_t end,
+			  int datasync)
+{
+	return fuse_fsync_common(file, start, end, datasync, 1);
+}
+
+static long fuse_dir_ioctl(struct file *file, unsigned int cmd,
+			    unsigned long arg)
+{
+	struct fuse_conn *fc = get_fuse_conn(file->f_mapping->host);
+
+	/* FUSE_IOCTL_DIR only supported for API version >= 7.18 */
+	if (fc->minor < 18)
+		return -ENOTTY;
+
+	return fuse_ioctl_common(file, cmd, arg, FUSE_IOCTL_DIR);
+}
+
+static long fuse_dir_compat_ioctl(struct file *file, unsigned int cmd,
+				   unsigned long arg)
+{
+	struct fuse_conn *fc = get_fuse_conn(file->f_mapping->host);
+
+	if (fc->minor < 18)
+		return -ENOTTY;
+
+	return fuse_ioctl_common(file, cmd, arg,
+				 FUSE_IOCTL_COMPAT | FUSE_IOCTL_DIR);
+}
+
+static bool update_mtime(unsigned ivalid, bool trust_local_mtime)
+{
+	/* Always update if mtime is explicitly set  */
+	if (ivalid & ATTR_MTIME_SET)
+		return true;
+
+	/* Or if kernel i_mtime is the official one */
+	if (trust_local_mtime)
+		return true;
+
+	/* If it's an open(O_TRUNC) or an ftruncate(), don't update */
+	if ((ivalid & ATTR_SIZE) && (ivalid & (ATTR_OPEN | ATTR_FILE)))
+		return false;
+
+	/* In all other cases update */
+	return true;
+}
+
+static void iattr_to_fattr(struct fuse_conn *fc, struct iattr *iattr,
+			   struct fuse_setattr_in *arg, bool trust_local_cmtime)
+{
+	unsigned ivalid = iattr->ia_valid;
+
+	if (ivalid & ATTR_MODE)
+		arg->valid |= FATTR_MODE,   arg->mode = iattr->ia_mode;
+	if (ivalid & ATTR_UID)
+		arg->valid |= FATTR_UID,    arg->uid = from_kuid(fc->user_ns, iattr->ia_uid);
+	if (ivalid & ATTR_GID)
+		arg->valid |= FATTR_GID,    arg->gid = from_kgid(fc->user_ns, iattr->ia_gid);
+	if (ivalid & ATTR_SIZE)
+		arg->valid |= FATTR_SIZE,   arg->size = iattr->ia_size;
+	if (ivalid & ATTR_ATIME) {
+		arg->valid |= FATTR_ATIME;
+		arg->atime = iattr->ia_atime.tv_sec;
+		arg->atimensec = iattr->ia_atime.tv_nsec;
+		if (!(ivalid & ATTR_ATIME_SET))
+			arg->valid |= FATTR_ATIME_NOW;
+	}
+	if ((ivalid & ATTR_MTIME) && update_mtime(ivalid, trust_local_cmtime)) {
+		arg->valid |= FATTR_MTIME;
+		arg->mtime = iattr->ia_mtime.tv_sec;
+		arg->mtimensec = iattr->ia_mtime.tv_nsec;
+		if (!(ivalid & ATTR_MTIME_SET) && !trust_local_cmtime)
+			arg->valid |= FATTR_MTIME_NOW;
+	}
+	if ((ivalid & ATTR_CTIME) && trust_local_cmtime) {
+		arg->valid |= FATTR_CTIME;
+		arg->ctime = iattr->ia_ctime.tv_sec;
+		arg->ctimensec = iattr->ia_ctime.tv_nsec;
+	}
+}
+
+/*
+ * Prevent concurrent writepages on inode
+ *
+ * This is done by adding a negative bias to the inode write counter
+ * and waiting for all pending writes to finish.
+ */
+void fuse_set_nowrite(struct inode *inode)
+{
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	struct fuse_inode *fi = get_fuse_inode(inode);
+
+	BUG_ON(!inode_is_locked(inode));
+
+	spin_lock(&fc->lock);
+	BUG_ON(fi->writectr < 0);
+	fi->writectr += FUSE_NOWRITE;
+	spin_unlock(&fc->lock);
+	wait_event(fi->page_waitq, fi->writectr == FUSE_NOWRITE);
+}
+
+/*
+ * Allow writepages on inode
+ *
+ * Remove the bias from the writecounter and send any queued
+ * writepages.
+ */
+static void __fuse_release_nowrite(struct inode *inode)
+{
+	struct fuse_inode *fi = get_fuse_inode(inode);
+
+	BUG_ON(fi->writectr != FUSE_NOWRITE);
+	fi->writectr = 0;
+	fuse_flush_writepages(inode);
+}
+
+void fuse_release_nowrite(struct inode *inode)
+{
+	struct fuse_conn *fc = get_fuse_conn(inode);
+
+	spin_lock(&fc->lock);
+	__fuse_release_nowrite(inode);
+	spin_unlock(&fc->lock);
+}
+
+static void fuse_setattr_fill(struct fuse_conn *fc, struct fuse_args *args,
+			      struct inode *inode,
+			      struct fuse_setattr_in *inarg_p,
+			      struct fuse_attr_out *outarg_p)
+{
+	args->in.h.opcode = FUSE_SETATTR;
+	args->in.h.nodeid = get_node_id(inode);
+	args->in.numargs = 1;
+	args->in.args[0].size = sizeof(*inarg_p);
+	args->in.args[0].value = inarg_p;
+	args->out.numargs = 1;
+	args->out.args[0].size = sizeof(*outarg_p);
+	args->out.args[0].value = outarg_p;
+}
+
+/*
+ * Flush inode->i_mtime to the server
+ */
+int fuse_flush_times(struct inode *inode, struct fuse_file *ff)
+{
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	FUSE_ARGS(args);
+	struct fuse_setattr_in inarg;
+	struct fuse_attr_out outarg;
+
+	memset(&inarg, 0, sizeof(inarg));
+	memset(&outarg, 0, sizeof(outarg));
+
+	inarg.valid = FATTR_MTIME;
+	inarg.mtime = inode->i_mtime.tv_sec;
+	inarg.mtimensec = inode->i_mtime.tv_nsec;
+	if (fc->minor >= 23) {
+		inarg.valid |= FATTR_CTIME;
+		inarg.ctime = inode->i_ctime.tv_sec;
+		inarg.ctimensec = inode->i_ctime.tv_nsec;
+	}
+	if (ff) {
+		inarg.valid |= FATTR_FH;
+		inarg.fh = ff->fh;
+	}
+	fuse_setattr_fill(fc, &args, inode, &inarg, &outarg);
+
+	return fuse_simple_request(fc, &args);
+}
+
+/*
+ * Set attributes, and at the same time refresh them.
+ *
+ * Truncation is slightly complicated, because the 'truncate' request
+ * may fail, in which case we don't want to touch the mapping.
+ * vmtruncate() doesn't allow for this case, so do the rlimit checking
+ * and the actual truncation by hand.
+ */
+int fuse_do_setattr(struct dentry *dentry, struct iattr *attr,
+		    struct file *file)
+{
+	struct inode *inode = d_inode(dentry);
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	struct fuse_inode *fi = get_fuse_inode(inode);
+	FUSE_ARGS(args);
+	struct fuse_setattr_in inarg;
+	struct fuse_attr_out outarg;
+	bool is_truncate = false;
+	bool is_wb = fc->writeback_cache;
+	loff_t oldsize;
+	int err;
+	bool trust_local_cmtime = is_wb && S_ISREG(inode->i_mode);
+
+	if (!fc->default_permissions)
+		attr->ia_valid |= ATTR_FORCE;
+
+	err = setattr_prepare(dentry, attr);
+	if (err)
+		return err;
+
+	if (attr->ia_valid & ATTR_OPEN) {
+		/* This is coming from open(..., ... | O_TRUNC); */
+		WARN_ON(!(attr->ia_valid & ATTR_SIZE));
+		WARN_ON(attr->ia_size != 0);
+		if (fc->atomic_o_trunc) {
+			/*
+			 * No need to send request to userspace, since actual
+			 * truncation has already been done by OPEN.  But still
+			 * need to truncate page cache.
+			 */
+			i_size_write(inode, 0);
+			truncate_pagecache(inode, 0);
+			return 0;
+		}
+		file = NULL;
+	}
+
+	if (attr->ia_valid & ATTR_SIZE)
+		is_truncate = true;
+
+	/* Flush dirty data/metadata before non-truncate SETATTR */
+	if (is_wb && S_ISREG(inode->i_mode) &&
+	    attr->ia_valid &
+			(ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_MTIME_SET |
+			 ATTR_TIMES_SET)) {
+		err = write_inode_now(inode, true);
+		if (err)
+			return err;
+
+		fuse_set_nowrite(inode);
+		fuse_release_nowrite(inode);
+	}
+
+	if (is_truncate) {
+		fuse_set_nowrite(inode);
+		set_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
+		if (trust_local_cmtime && attr->ia_size != inode->i_size)
+			attr->ia_valid |= ATTR_MTIME | ATTR_CTIME;
+	}
+
+	memset(&inarg, 0, sizeof(inarg));
+	memset(&outarg, 0, sizeof(outarg));
+	iattr_to_fattr(fc, attr, &inarg, trust_local_cmtime);
+	if (file) {
+		struct fuse_file *ff = file->private_data;
+		inarg.valid |= FATTR_FH;
+		inarg.fh = ff->fh;
+	}
+	if (attr->ia_valid & ATTR_SIZE) {
+		/* For mandatory locking in truncate */
+		inarg.valid |= FATTR_LOCKOWNER;
+		inarg.lock_owner = fuse_lock_owner_id(fc, current->files);
+	}
+	fuse_setattr_fill(fc, &args, inode, &inarg, &outarg);
+	err = fuse_simple_request(fc, &args);
+	if (err) {
+		if (err == -EINTR)
+			fuse_invalidate_attr(inode);
+		goto error;
+	}
+
+	if (fuse_invalid_attr(&outarg.attr) ||
+	    (inode->i_mode ^ outarg.attr.mode) & S_IFMT) {
+		fuse_make_bad(inode);
+		err = -EIO;
+		goto error;
+	}
+
+	spin_lock(&fc->lock);
+	/* the kernel maintains i_mtime locally */
+	if (trust_local_cmtime) {
+		if (attr->ia_valid & ATTR_MTIME)
+			inode->i_mtime = attr->ia_mtime;
+		if (attr->ia_valid & ATTR_CTIME)
+			inode->i_ctime = attr->ia_ctime;
+		/* FIXME: clear I_DIRTY_SYNC? */
+	}
+
+	fuse_change_attributes_common(inode, &outarg.attr,
+				      attr_timeout(&outarg));
+	oldsize = inode->i_size;
+	/* see the comment in fuse_change_attributes() */
+	if (!is_wb || is_truncate || !S_ISREG(inode->i_mode))
+		i_size_write(inode, outarg.attr.size);
+
+	if (is_truncate) {
+		/* NOTE: this may release/reacquire fc->lock */
+		__fuse_release_nowrite(inode);
+	}
+	spin_unlock(&fc->lock);
+
+	/*
+	 * Only call invalidate_inode_pages2() after removing
+	 * FUSE_NOWRITE, otherwise fuse_launder_page() would deadlock.
+	 */
+	if ((is_truncate || !is_wb) &&
+	    S_ISREG(inode->i_mode) && oldsize != outarg.attr.size) {
+		truncate_pagecache(inode, outarg.attr.size);
+		invalidate_inode_pages2(inode->i_mapping);
+	}
+
+	clear_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
+	return 0;
+
+error:
+	if (is_truncate)
+		fuse_release_nowrite(inode);
+
+	clear_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
+	return err;
+}
+
+static int fuse_setattr(struct dentry *entry, struct iattr *attr)
+{
+	struct inode *inode = d_inode(entry);
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	struct file *file = (attr->ia_valid & ATTR_FILE) ? attr->ia_file : NULL;
+	int ret;
+
+	if (fuse_is_bad(inode))
+		return -EIO;
+
+	if (!fuse_allow_current_process(get_fuse_conn(inode)))
+		return -EACCES;
+
+	if (attr->ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID)) {
+		attr->ia_valid &= ~(ATTR_KILL_SUID | ATTR_KILL_SGID |
+				    ATTR_MODE);
+
+		/*
+		 * The only sane way to reliably kill suid/sgid is to do it in
+		 * the userspace filesystem
+		 *
+		 * This should be done on write(), truncate() and chown().
+		 */
+		if (!fc->handle_killpriv) {
+			/*
+			 * ia_mode calculation may have used stale i_mode.
+			 * Refresh and recalculate.
+			 */
+			ret = fuse_do_getattr(inode, NULL, file);
+			if (ret)
+				return ret;
+
+			attr->ia_mode = inode->i_mode;
+			if (inode->i_mode & S_ISUID) {
+				attr->ia_valid |= ATTR_MODE;
+				attr->ia_mode &= ~S_ISUID;
+			}
+			if ((inode->i_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
+				attr->ia_valid |= ATTR_MODE;
+				attr->ia_mode &= ~S_ISGID;
+			}
+		}
+	}
+	if (!attr->ia_valid)
+		return 0;
+
+	ret = fuse_do_setattr(entry, attr, file);
+	if (!ret) {
+		/*
+		 * If filesystem supports acls it may have updated acl xattrs in
+		 * the filesystem, so forget cached acls for the inode.
+		 */
+		if (fc->posix_acl)
+			forget_all_cached_acls(inode);
+
+		/* Directory mode changed, may need to revalidate access */
+		if (d_is_dir(entry) && (attr->ia_valid & ATTR_MODE))
+			fuse_invalidate_entry_cache(entry);
+	}
+	return ret;
+}
+
+static int fuse_getattr(const struct path *path, struct kstat *stat,
+			u32 request_mask, unsigned int flags)
+{
+	struct inode *inode = d_inode(path->dentry);
+	struct fuse_conn *fc = get_fuse_conn(inode);
+
+	if (fuse_is_bad(inode))
+		return -EIO;
+
+	if (!fuse_allow_current_process(fc))
+		return -EACCES;
+
+	return fuse_update_get_attr(inode, NULL, stat, flags);
+}
+
+static const struct inode_operations fuse_dir_inode_operations = {
+	.lookup		= fuse_lookup,
+	.mkdir		= fuse_mkdir,
+	.symlink	= fuse_symlink,
+	.unlink		= fuse_unlink,
+	.rmdir		= fuse_rmdir,
+	.rename		= fuse_rename2,
+	.link		= fuse_link,
+	.setattr	= fuse_setattr,
+	.create		= fuse_create,
+	.atomic_open	= fuse_atomic_open,
+	.mknod		= fuse_mknod,
+	.permission	= fuse_permission,
+	.getattr	= fuse_getattr,
+	.listxattr	= fuse_listxattr,
+	.get_acl	= fuse_get_acl,
+	.set_acl	= fuse_set_acl,
+};
+
+static const struct file_operations fuse_dir_operations = {
+	.llseek		= generic_file_llseek,
+	.read		= generic_read_dir,
+	.iterate_shared	= fuse_readdir,
+	.open		= fuse_dir_open,
+	.release	= fuse_dir_release,
+	.fsync		= fuse_dir_fsync,
+	.unlocked_ioctl	= fuse_dir_ioctl,
+	.compat_ioctl	= fuse_dir_compat_ioctl,
+};
+
+static const struct inode_operations fuse_common_inode_operations = {
+	.setattr	= fuse_setattr,
+	.permission	= fuse_permission,
+	.getattr	= fuse_getattr,
+	.listxattr	= fuse_listxattr,
+	.get_acl	= fuse_get_acl,
+	.set_acl	= fuse_set_acl,
+};
+
+static const struct inode_operations fuse_symlink_inode_operations = {
+	.setattr	= fuse_setattr,
+	.get_link	= fuse_get_link,
+	.getattr	= fuse_getattr,
+	.listxattr	= fuse_listxattr,
+};
+
+void fuse_init_common(struct inode *inode)
+{
+	inode->i_op = &fuse_common_inode_operations;
+}
+
+void fuse_init_dir(struct inode *inode)
+{
+	inode->i_op = &fuse_dir_inode_operations;
+	inode->i_fop = &fuse_dir_operations;
+}
+
+void fuse_init_symlink(struct inode *inode)
+{
+	inode->i_op = &fuse_symlink_inode_operations;
+}