From e636c8d336489bf3eed5878299e6cc045bbad077 Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:17:29 +0000
Subject: [PATCH] debug lk

---
 kernel/fs/fuse/inode.c | 1076 ++++++++++++++++++++++++++++++++++++++++-------------------
 1 files changed, 722 insertions(+), 354 deletions(-)

diff --git a/kernel/fs/fuse/inode.c b/kernel/fs/fuse/inode.c
index 821597c..47490cc 100644
--- a/kernel/fs/fuse/inode.c
+++ b/kernel/fs/fuse/inode.c
@@ -15,7 +15,8 @@
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
-#include <linux/parser.h>
+#include <linux/fs_context.h>
+#include <linux/fs_parser.h>
 #include <linux/statfs.h>
 #include <linux/random.h>
 #include <linux/sched.h>
@@ -26,6 +27,7 @@
 MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
 MODULE_DESCRIPTION("Filesystem in Userspace");
 MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(ANDROID_GKI_VFS_EXPORT_ONLY);
 
 static struct kmem_cache *fuse_inode_cachep;
 struct list_head fuse_conn_list;
@@ -59,89 +61,93 @@
 /** Congestion starts at 75% of maximum */
 #define FUSE_DEFAULT_CONGESTION_THRESHOLD (FUSE_DEFAULT_MAX_BACKGROUND * 3 / 4)
 
-struct fuse_mount_data {
-	int fd;
-	unsigned rootmode;
-	kuid_t user_id;
-	kgid_t group_id;
-	unsigned fd_present:1;
-	unsigned rootmode_present:1;
-	unsigned user_id_present:1;
-	unsigned group_id_present:1;
-	unsigned default_permissions:1;
-	unsigned allow_other:1;
-	unsigned max_read;
-	unsigned blksize;
-};
+#ifdef CONFIG_BLOCK
+static struct file_system_type fuseblk_fs_type;
+#endif
 
 struct fuse_forget_link *fuse_alloc_forget(void)
 {
-	return kzalloc(sizeof(struct fuse_forget_link), GFP_KERNEL);
+	return kzalloc(sizeof(struct fuse_forget_link), GFP_KERNEL_ACCOUNT);
 }
 
 static struct inode *fuse_alloc_inode(struct super_block *sb)
 {
-	struct inode *inode;
 	struct fuse_inode *fi;
 
-	inode = kmem_cache_alloc(fuse_inode_cachep, GFP_KERNEL);
-	if (!inode)
+	fi = kmem_cache_alloc(fuse_inode_cachep, GFP_KERNEL);
+	if (!fi)
 		return NULL;
 
-	fi = get_fuse_inode(inode);
 	fi->i_time = 0;
+	fi->inval_mask = 0;
 	fi->nodeid = 0;
 	fi->nlookup = 0;
 	fi->attr_version = 0;
-	fi->writectr = 0;
 	fi->orig_ino = 0;
 	fi->state = 0;
-	INIT_LIST_HEAD(&fi->write_files);
-	INIT_LIST_HEAD(&fi->queued_writes);
-	INIT_LIST_HEAD(&fi->writepages);
-	init_waitqueue_head(&fi->page_waitq);
 	mutex_init(&fi->mutex);
+	init_rwsem(&fi->i_mmap_sem);
+	spin_lock_init(&fi->lock);
 	fi->forget = fuse_alloc_forget();
-	if (!fi->forget) {
-		kmem_cache_free(fuse_inode_cachep, inode);
-		return NULL;
-	}
+	if (!fi->forget)
+		goto out_free;
 
-	return inode;
+	if (IS_ENABLED(CONFIG_FUSE_DAX) && !fuse_dax_inode_alloc(sb, fi))
+		goto out_free_forget;
+
+	return &fi->inode;
+
+out_free_forget:
+	kfree(fi->forget);
+out_free:
+	kmem_cache_free(fuse_inode_cachep, fi);
+	return NULL;
 }
 
-static void fuse_i_callback(struct rcu_head *head)
-{
-	struct inode *inode = container_of(head, struct inode, i_rcu);
-	kmem_cache_free(fuse_inode_cachep, inode);
-}
-
-static void fuse_destroy_inode(struct inode *inode)
+static void fuse_free_inode(struct inode *inode)
 {
 	struct fuse_inode *fi = get_fuse_inode(inode);
-	BUG_ON(!list_empty(&fi->write_files));
-	BUG_ON(!list_empty(&fi->queued_writes));
+
 	mutex_destroy(&fi->mutex);
 	kfree(fi->forget);
-	call_rcu(&inode->i_rcu, fuse_i_callback);
+#ifdef CONFIG_FUSE_DAX
+	kfree(fi->dax);
+#endif
+	kmem_cache_free(fuse_inode_cachep, fi);
 }
 
 static void fuse_evict_inode(struct inode *inode)
 {
+	struct fuse_inode *fi = get_fuse_inode(inode);
+
+	/* Will write inode on close/munmap and in all other dirtiers */
+	WARN_ON(inode->i_state & I_DIRTY_INODE);
+
 	truncate_inode_pages_final(&inode->i_data);
 	clear_inode(inode);
 	if (inode->i_sb->s_flags & SB_ACTIVE) {
 		struct fuse_conn *fc = get_fuse_conn(inode);
-		struct fuse_inode *fi = get_fuse_inode(inode);
-		fuse_queue_forget(fc, fi->forget, fi->nodeid, fi->nlookup);
-		fi->forget = NULL;
+
+		if (FUSE_IS_DAX(inode))
+			fuse_dax_inode_cleanup(inode);
+		if (fi->nlookup) {
+			fuse_queue_forget(fc, fi->forget, fi->nodeid,
+					  fi->nlookup);
+			fi->forget = NULL;
+		}
+	}
+	if (S_ISREG(inode->i_mode) && !fuse_is_bad(inode)) {
+		WARN_ON(!list_empty(&fi->write_files));
+		WARN_ON(!list_empty(&fi->queued_writes));
 	}
 }
 
-static int fuse_remount_fs(struct super_block *sb, int *flags, char *data)
+static int fuse_reconfigure(struct fs_context *fc)
 {
+	struct super_block *sb = fc->root->d_sb;
+
 	sync_filesystem(sb);
-	if (*flags & SB_MANDLOCK)
+	if (fc->sb_flags & SB_MANDLOCK)
 		return -EINVAL;
 
 	return 0;
@@ -165,8 +171,11 @@
 	struct fuse_conn *fc = get_fuse_conn(inode);
 	struct fuse_inode *fi = get_fuse_inode(inode);
 
-	fi->attr_version = ++fc->attr_version;
+	lockdep_assert_held(&fi->lock);
+
+	fi->attr_version = atomic64_inc_return(&fc->attr_version);
 	fi->i_time = attr_valid;
+	WRITE_ONCE(fi->inval_mask, 0);
 
 	inode->i_ino     = fuse_squash_ino(attr->ino);
 	inode->i_mode    = (inode->i_mode & S_IFMT) | (attr->mode & 07777);
@@ -174,6 +183,12 @@
 	inode->i_uid     = make_kuid(fc->user_ns, attr->uid);
 	inode->i_gid     = make_kgid(fc->user_ns, attr->gid);
 	inode->i_blocks  = attr->blocks;
+
+	/* Sanitize nsecs */
+	attr->atimensec = min_t(u32, attr->atimensec, NSEC_PER_SEC - 1);
+	attr->mtimensec = min_t(u32, attr->mtimensec, NSEC_PER_SEC - 1);
+	attr->ctimensec = min_t(u32, attr->ctimensec, NSEC_PER_SEC - 1);
+
 	inode->i_atime.tv_sec   = attr->atime;
 	inode->i_atime.tv_nsec  = attr->atimensec;
 	/* mtime from server may be stale due to local buffered write */
@@ -210,10 +225,10 @@
 	loff_t oldsize;
 	struct timespec64 old_mtime;
 
-	spin_lock(&fc->lock);
+	spin_lock(&fi->lock);
 	if ((attr_version != 0 && fi->attr_version > attr_version) ||
 	    test_bit(FUSE_I_SIZE_UNSTABLE, &fi->state)) {
-		spin_unlock(&fc->lock);
+		spin_unlock(&fi->lock);
 		return;
 	}
 
@@ -228,14 +243,15 @@
 	 */
 	if (!is_wb || !S_ISREG(inode->i_mode))
 		i_size_write(inode, attr->size);
-	spin_unlock(&fc->lock);
+	spin_unlock(&fi->lock);
 
 	if (!is_wb && S_ISREG(inode->i_mode)) {
 		bool inval = false;
 
 		if (oldsize != attr->size) {
 			truncate_pagecache(inode, attr->size);
-			inval = true;
+			if (!fc->explicit_inval_data)
+				inval = true;
 		} else if (fc->auto_inval_data) {
 			struct timespec64 new_mtime = {
 				.tv_sec = attr->mtime,
@@ -279,7 +295,7 @@
 		BUG();
 }
 
-int fuse_inode_eq(struct inode *inode, void *_nodeidp)
+static int fuse_inode_eq(struct inode *inode, void *_nodeidp)
 {
 	u64 nodeid = *(u64 *) _nodeidp;
 	if (get_node_id(inode) == nodeid)
@@ -303,7 +319,26 @@
 	struct fuse_inode *fi;
 	struct fuse_conn *fc = get_fuse_conn_super(sb);
 
- retry:
+	/*
+	 * Auto mount points get their node id from the submount root, which is
+	 * not a unique identifier within this filesystem.
+	 *
+	 * To avoid conflicts, do not place submount points into the inode hash
+	 * table.
+	 */
+	if (fc->auto_submounts && (attr->flags & FUSE_ATTR_SUBMOUNT) &&
+	    S_ISDIR(attr->mode)) {
+		inode = new_inode(sb);
+		if (!inode)
+			return NULL;
+
+		fuse_init_inode(inode, attr);
+		get_fuse_inode(inode)->nodeid = nodeid;
+		inode->i_flags |= S_AUTOMOUNT;
+		goto done;
+	}
+
+retry:
 	inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set, &nodeid);
 	if (!inode)
 		return NULL;
@@ -315,32 +350,60 @@
 		inode->i_generation = generation;
 		fuse_init_inode(inode, attr);
 		unlock_new_inode(inode);
-	} else if ((inode->i_mode ^ attr->mode) & S_IFMT) {
-		/* Inode has changed type, any I/O on the old should fail */
+	} else if (fuse_stale_inode(inode, generation, attr)) {
+		/* nodeid was reused, any I/O on the old inode should fail */
 		fuse_make_bad(inode);
 		iput(inode);
 		goto retry;
 	}
-
+done:
 	fi = get_fuse_inode(inode);
-	spin_lock(&fc->lock);
+	spin_lock(&fi->lock);
 	fi->nlookup++;
-	spin_unlock(&fc->lock);
+	spin_unlock(&fi->lock);
 	fuse_change_attributes(inode, attr, attr_valid, attr_version);
 
 	return inode;
 }
 
-int fuse_reverse_inval_inode(struct super_block *sb, u64 nodeid,
+struct inode *fuse_ilookup(struct fuse_conn *fc, u64 nodeid,
+			   struct fuse_mount **fm)
+{
+	struct fuse_mount *fm_iter;
+	struct inode *inode;
+
+	WARN_ON(!rwsem_is_locked(&fc->killsb));
+	list_for_each_entry(fm_iter, &fc->mounts, fc_entry) {
+		if (!fm_iter->sb)
+			continue;
+
+		inode = ilookup5(fm_iter->sb, nodeid, fuse_inode_eq, &nodeid);
+		if (inode) {
+			if (fm)
+				*fm = fm_iter;
+			return inode;
+		}
+	}
+
+	return NULL;
+}
+
+int fuse_reverse_inval_inode(struct fuse_conn *fc, u64 nodeid,
 			     loff_t offset, loff_t len)
 {
+	struct fuse_inode *fi;
 	struct inode *inode;
 	pgoff_t pg_start;
 	pgoff_t pg_end;
 
-	inode = ilookup5(sb, nodeid, fuse_inode_eq, &nodeid);
+	inode = fuse_ilookup(fc, nodeid, NULL);
 	if (!inode)
 		return -ENOENT;
+
+	fi = get_fuse_inode(inode);
+	spin_lock(&fi->lock);
+	fi->attr_version = atomic64_inc_return(&fc->attr_version);
+	spin_unlock(&fi->lock);
 
 	fuse_invalidate_attr(inode);
 	forget_all_cached_acls(inode);
@@ -377,32 +440,29 @@
 
 static void fuse_umount_begin(struct super_block *sb)
 {
-	fuse_abort_conn(get_fuse_conn_super(sb), false);
+	struct fuse_conn *fc = get_fuse_conn_super(sb);
+
+	if (!fc->no_force_umount)
+		fuse_abort_conn(fc);
 }
 
-static void fuse_send_destroy(struct fuse_conn *fc)
+static void fuse_send_destroy(struct fuse_mount *fm)
 {
-	struct fuse_req *req = fc->destroy_req;
-	if (req && fc->conn_init) {
-		fc->destroy_req = NULL;
-		req->in.h.opcode = FUSE_DESTROY;
-		__set_bit(FR_FORCE, &req->flags);
-		__clear_bit(FR_BACKGROUND, &req->flags);
-		fuse_request_send(fc, req);
-		fuse_put_request(fc, req);
+	if (fm->fc->conn_init) {
+		FUSE_ARGS(args);
+
+		args.opcode = FUSE_DESTROY;
+		args.force = true;
+		args.nocreds = true;
+		fuse_simple_request(fm, &args);
 	}
 }
 
 static void fuse_put_super(struct super_block *sb)
 {
-	struct fuse_conn *fc = get_fuse_conn_super(sb);
+	struct fuse_mount *fm = get_fuse_mount_super(sb);
 
-	mutex_lock(&fuse_mutex);
-	list_del(&fc->entry);
-	fuse_ctl_remove_conn(fc);
-	mutex_unlock(&fuse_mutex);
-
-	fuse_conn_put(fc);
+	fuse_mount_put(fm);
 }
 
 static void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatfs *attr)
@@ -422,30 +482,32 @@
 static int fuse_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
 	struct super_block *sb = dentry->d_sb;
-	struct fuse_conn *fc = get_fuse_conn_super(sb);
+	struct fuse_mount *fm = get_fuse_mount_super(sb);
 	FUSE_ARGS(args);
 	struct fuse_statfs_out outarg;
 	int err;
 
-	if (!fuse_allow_current_process(fc)) {
+	if (!fuse_allow_current_process(fm->fc)) {
 		buf->f_type = FUSE_SUPER_MAGIC;
 		return 0;
 	}
 
 	memset(&outarg, 0, sizeof(outarg));
-	args.in.numargs = 0;
-	args.in.h.opcode = FUSE_STATFS;
-	args.in.h.nodeid = get_node_id(d_inode(dentry));
-	args.out.numargs = 1;
-	args.out.args[0].size = sizeof(outarg);
-	args.out.args[0].value = &outarg;
-	err = fuse_simple_request(fc, &args);
+	args.in_numargs = 0;
+	args.opcode = FUSE_STATFS;
+	args.nodeid = get_node_id(d_inode(dentry));
+	args.out_numargs = 1;
+	args.out_args[0].size = sizeof(outarg);
+	args.out_args[0].value = &outarg;
+	err = fuse_simple_request(fm, &args);
 	if (!err)
 		convert_fuse_statfs(buf, &outarg.st);
 	return err;
 }
 
 enum {
+	OPT_SOURCE,
+	OPT_SUBTYPE,
 	OPT_FD,
 	OPT_ROOTMODE,
 	OPT_USER_ID,
@@ -457,111 +519,115 @@
 	OPT_ERR
 };
 
-static const match_table_t tokens = {
-	{OPT_FD,			"fd=%u"},
-	{OPT_ROOTMODE,			"rootmode=%o"},
-	{OPT_USER_ID,			"user_id=%u"},
-	{OPT_GROUP_ID,			"group_id=%u"},
-	{OPT_DEFAULT_PERMISSIONS,	"default_permissions"},
-	{OPT_ALLOW_OTHER,		"allow_other"},
-	{OPT_MAX_READ,			"max_read=%u"},
-	{OPT_BLKSIZE,			"blksize=%u"},
-	{OPT_ERR,			NULL}
+static const struct fs_parameter_spec fuse_fs_parameters[] = {
+	fsparam_string	("source",		OPT_SOURCE),
+	fsparam_u32	("fd",			OPT_FD),
+	fsparam_u32oct	("rootmode",		OPT_ROOTMODE),
+	fsparam_u32	("user_id",		OPT_USER_ID),
+	fsparam_u32	("group_id",		OPT_GROUP_ID),
+	fsparam_flag	("default_permissions",	OPT_DEFAULT_PERMISSIONS),
+	fsparam_flag	("allow_other",		OPT_ALLOW_OTHER),
+	fsparam_u32	("max_read",		OPT_MAX_READ),
+	fsparam_u32	("blksize",		OPT_BLKSIZE),
+	fsparam_string	("subtype",		OPT_SUBTYPE),
+	{}
 };
 
-static int fuse_match_uint(substring_t *s, unsigned int *res)
+static int fuse_parse_param(struct fs_context *fc, struct fs_parameter *param)
 {
-	int err = -ENOMEM;
-	char *buf = match_strdup(s);
-	if (buf) {
-		err = kstrtouint(buf, 10, res);
-		kfree(buf);
-	}
-	return err;
-}
+	struct fs_parse_result result;
+	struct fuse_fs_context *ctx = fc->fs_private;
+	int opt;
 
-static int parse_fuse_opt(char *opt, struct fuse_mount_data *d, int is_bdev,
-			  struct user_namespace *user_ns)
-{
-	char *p;
-	memset(d, 0, sizeof(struct fuse_mount_data));
-	d->max_read = ~0;
-	d->blksize = FUSE_DEFAULT_BLKSIZE;
-
-	while ((p = strsep(&opt, ",")) != NULL) {
-		int token;
-		int value;
-		unsigned uv;
-		substring_t args[MAX_OPT_ARGS];
-		if (!*p)
-			continue;
-
-		token = match_token(p, tokens, args);
-		switch (token) {
-		case OPT_FD:
-			if (match_int(&args[0], &value))
-				return 0;
-			d->fd = value;
-			d->fd_present = 1;
-			break;
-
-		case OPT_ROOTMODE:
-			if (match_octal(&args[0], &value))
-				return 0;
-			if (!fuse_valid_type(value))
-				return 0;
-			d->rootmode = value;
-			d->rootmode_present = 1;
-			break;
-
-		case OPT_USER_ID:
-			if (fuse_match_uint(&args[0], &uv))
-				return 0;
-			d->user_id = make_kuid(user_ns, uv);
-			if (!uid_valid(d->user_id))
-				return 0;
-			d->user_id_present = 1;
-			break;
-
-		case OPT_GROUP_ID:
-			if (fuse_match_uint(&args[0], &uv))
-				return 0;
-			d->group_id = make_kgid(user_ns, uv);
-			if (!gid_valid(d->group_id))
-				return 0;
-			d->group_id_present = 1;
-			break;
-
-		case OPT_DEFAULT_PERMISSIONS:
-			d->default_permissions = 1;
-			break;
-
-		case OPT_ALLOW_OTHER:
-			d->allow_other = 1;
-			break;
-
-		case OPT_MAX_READ:
-			if (match_int(&args[0], &value))
-				return 0;
-			d->max_read = value;
-			break;
-
-		case OPT_BLKSIZE:
-			if (!is_bdev || match_int(&args[0], &value))
-				return 0;
-			d->blksize = value;
-			break;
-
-		default:
+	if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) {
+		/*
+		 * Ignore options coming from mount(MS_REMOUNT) for backward
+		 * compatibility.
+		 */
+		if (fc->oldapi)
 			return 0;
-		}
+
+		return invalfc(fc, "No changes allowed in reconfigure");
 	}
 
-	if (!d->fd_present || !d->rootmode_present ||
-	    !d->user_id_present || !d->group_id_present)
+	opt = fs_parse(fc, fuse_fs_parameters, param, &result);
+	if (opt < 0)
+		return opt;
+
+	switch (opt) {
+	case OPT_SOURCE:
+		if (fc->source)
+			return invalfc(fc, "Multiple sources specified");
+		fc->source = param->string;
+		param->string = NULL;
+		break;
+
+	case OPT_SUBTYPE:
+		if (ctx->subtype)
+			return invalfc(fc, "Multiple subtypes specified");
+		ctx->subtype = param->string;
+		param->string = NULL;
 		return 0;
 
-	return 1;
+	case OPT_FD:
+		ctx->fd = result.uint_32;
+		ctx->fd_present = true;
+		break;
+
+	case OPT_ROOTMODE:
+		if (!fuse_valid_type(result.uint_32))
+			return invalfc(fc, "Invalid rootmode");
+		ctx->rootmode = result.uint_32;
+		ctx->rootmode_present = true;
+		break;
+
+	case OPT_USER_ID:
+		ctx->user_id = make_kuid(fc->user_ns, result.uint_32);
+		if (!uid_valid(ctx->user_id))
+			return invalfc(fc, "Invalid user_id");
+		ctx->user_id_present = true;
+		break;
+
+	case OPT_GROUP_ID:
+		ctx->group_id = make_kgid(fc->user_ns, result.uint_32);
+		if (!gid_valid(ctx->group_id))
+			return invalfc(fc, "Invalid group_id");
+		ctx->group_id_present = true;
+		break;
+
+	case OPT_DEFAULT_PERMISSIONS:
+		ctx->default_permissions = true;
+		break;
+
+	case OPT_ALLOW_OTHER:
+		ctx->allow_other = true;
+		break;
+
+	case OPT_MAX_READ:
+		ctx->max_read = result.uint_32;
+		break;
+
+	case OPT_BLKSIZE:
+		if (!ctx->is_bdev)
+			return invalfc(fc, "blksize only supported for fuseblk");
+		ctx->blksize = result.uint_32;
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void fuse_free_fc(struct fs_context *fc)
+{
+	struct fuse_fs_context *ctx = fc->fs_private;
+
+	if (ctx) {
+		kfree(ctx->subtype);
+		kfree(ctx);
+	}
 }
 
 static int fuse_show_options(struct seq_file *m, struct dentry *root)
@@ -569,20 +635,31 @@
 	struct super_block *sb = root->d_sb;
 	struct fuse_conn *fc = get_fuse_conn_super(sb);
 
-	seq_printf(m, ",user_id=%u", from_kuid_munged(fc->user_ns, fc->user_id));
-	seq_printf(m, ",group_id=%u", from_kgid_munged(fc->user_ns, fc->group_id));
-	if (fc->default_permissions)
-		seq_puts(m, ",default_permissions");
-	if (fc->allow_other)
-		seq_puts(m, ",allow_other");
-	if (fc->max_read != ~0)
-		seq_printf(m, ",max_read=%u", fc->max_read);
-	if (sb->s_bdev && sb->s_blocksize != FUSE_DEFAULT_BLKSIZE)
-		seq_printf(m, ",blksize=%lu", sb->s_blocksize);
+	if (fc->legacy_opts_show) {
+		seq_printf(m, ",user_id=%u",
+			   from_kuid_munged(fc->user_ns, fc->user_id));
+		seq_printf(m, ",group_id=%u",
+			   from_kgid_munged(fc->user_ns, fc->group_id));
+		if (fc->default_permissions)
+			seq_puts(m, ",default_permissions");
+		if (fc->allow_other)
+			seq_puts(m, ",allow_other");
+		if (fc->max_read != ~0)
+			seq_printf(m, ",max_read=%u", fc->max_read);
+		if (sb->s_bdev && sb->s_blocksize != FUSE_DEFAULT_BLKSIZE)
+			seq_printf(m, ",blksize=%lu", sb->s_blocksize);
+	}
+#ifdef CONFIG_FUSE_DAX
+	if (fc->dax)
+		seq_puts(m, ",dax");
+#endif
+
 	return 0;
 }
 
-static void fuse_iqueue_init(struct fuse_iqueue *fiq)
+static void fuse_iqueue_init(struct fuse_iqueue *fiq,
+			     const struct fuse_iqueue_ops *ops,
+			     void *priv)
 {
 	memset(fiq, 0, sizeof(struct fuse_iqueue));
 	spin_lock_init(&fiq->lock);
@@ -591,50 +668,69 @@
 	INIT_LIST_HEAD(&fiq->interrupts);
 	fiq->forget_list_tail = &fiq->forget_list_head;
 	fiq->connected = 1;
+	fiq->ops = ops;
+	fiq->priv = priv;
 }
 
 static void fuse_pqueue_init(struct fuse_pqueue *fpq)
 {
-	memset(fpq, 0, sizeof(struct fuse_pqueue));
+	unsigned int i;
+
 	spin_lock_init(&fpq->lock);
-	INIT_LIST_HEAD(&fpq->processing);
+	for (i = 0; i < FUSE_PQ_HASH_SIZE; i++)
+		INIT_LIST_HEAD(&fpq->processing[i]);
 	INIT_LIST_HEAD(&fpq->io);
 	fpq->connected = 1;
 }
 
-void fuse_conn_init(struct fuse_conn *fc, struct user_namespace *user_ns)
+void fuse_conn_init(struct fuse_conn *fc, struct fuse_mount *fm,
+		    struct user_namespace *user_ns,
+		    const struct fuse_iqueue_ops *fiq_ops, void *fiq_priv)
 {
 	memset(fc, 0, sizeof(*fc));
 	spin_lock_init(&fc->lock);
+	spin_lock_init(&fc->bg_lock);
+	spin_lock_init(&fc->passthrough_req_lock);
 	init_rwsem(&fc->killsb);
 	refcount_set(&fc->count, 1);
 	atomic_set(&fc->dev_count, 1);
 	init_waitqueue_head(&fc->blocked_waitq);
-	init_waitqueue_head(&fc->reserved_req_waitq);
-	fuse_iqueue_init(&fc->iq);
+	fuse_iqueue_init(&fc->iq, fiq_ops, fiq_priv);
 	INIT_LIST_HEAD(&fc->bg_queue);
 	INIT_LIST_HEAD(&fc->entry);
 	INIT_LIST_HEAD(&fc->devices);
+	idr_init(&fc->passthrough_req);
 	atomic_set(&fc->num_waiting, 0);
 	fc->max_background = FUSE_DEFAULT_MAX_BACKGROUND;
 	fc->congestion_threshold = FUSE_DEFAULT_CONGESTION_THRESHOLD;
-	fc->khctr = 0;
+	atomic64_set(&fc->khctr, 0);
 	fc->polled_files = RB_ROOT;
 	fc->blocked = 0;
 	fc->initialized = 0;
 	fc->connected = 1;
-	fc->attr_version = 1;
+	atomic64_set(&fc->attr_version, 1);
 	get_random_bytes(&fc->scramble_key, sizeof(fc->scramble_key));
 	fc->pid_ns = get_pid_ns(task_active_pid_ns(current));
 	fc->user_ns = get_user_ns(user_ns);
+	fc->max_pages = FUSE_DEFAULT_MAX_PAGES_PER_REQ;
+	fc->max_pages_limit = FUSE_MAX_MAX_PAGES;
+
+	INIT_LIST_HEAD(&fc->mounts);
+	list_add(&fm->fc_entry, &fc->mounts);
+	fm->fc = fc;
+	refcount_set(&fm->count, 1);
 }
 EXPORT_SYMBOL_GPL(fuse_conn_init);
 
 void fuse_conn_put(struct fuse_conn *fc)
 {
 	if (refcount_dec_and_test(&fc->count)) {
-		if (fc->destroy_req)
-			fuse_request_free(fc->destroy_req);
+		struct fuse_iqueue *fiq = &fc->iq;
+
+		if (IS_ENABLED(CONFIG_FUSE_DAX))
+			fuse_dax_conn_free(fc);
+		if (fiq->ops->release)
+			fiq->ops->release(fiq);
 		put_pid_ns(fc->pid_ns);
 		put_user_ns(fc->user_ns);
 		fc->release(fc);
@@ -648,6 +744,23 @@
 	return fc;
 }
 EXPORT_SYMBOL_GPL(fuse_conn_get);
+
+void fuse_mount_put(struct fuse_mount *fm)
+{
+	if (refcount_dec_and_test(&fm->count)) {
+		if (fm->fc)
+			fuse_conn_put(fm->fc);
+		kfree(fm);
+	}
+}
+EXPORT_SYMBOL_GPL(fuse_mount_put);
+
+struct fuse_mount *fuse_mount_get(struct fuse_mount *fm)
+{
+	refcount_inc(&fm->count);
+	return fm;
+}
+EXPORT_SYMBOL_GPL(fuse_mount_get);
 
 static struct inode *fuse_get_root_inode(struct super_block *sb, unsigned mode)
 {
@@ -809,11 +922,10 @@
 
 static const struct super_operations fuse_super_operations = {
 	.alloc_inode    = fuse_alloc_inode,
-	.destroy_inode  = fuse_destroy_inode,
+	.free_inode     = fuse_free_inode,
 	.evict_inode	= fuse_evict_inode,
 	.write_inode	= fuse_write_inode,
 	.drop_inode	= generic_delete_inode,
-	.remount_fs	= fuse_remount_fs,
 	.put_super	= fuse_put_super,
 	.umount_begin	= fuse_umount_begin,
 	.statfs		= fuse_statfs,
@@ -822,9 +934,12 @@
 
 static void sanitize_global_limit(unsigned *limit)
 {
+	/*
+	 * The default maximum number of async requests is calculated to consume
+	 * 1/2^13 of the total memory, assuming 392 bytes per request.
+	 */
 	if (*limit == 0)
-		*limit = ((totalram_pages << PAGE_SHIFT) >> 13) /
-			 sizeof(struct fuse_req);
+		*limit = ((totalram_pages() << PAGE_SHIFT) >> 13) / 392;
 
 	if (*limit >= 1 << 16)
 		*limit = (1 << 16) - 1;
@@ -853,6 +968,7 @@
 	sanitize_global_limit(&max_user_bgreq);
 	sanitize_global_limit(&max_user_congthresh);
 
+	spin_lock(&fc->bg_lock);
 	if (arg->max_background) {
 		fc->max_background = arg->max_background;
 
@@ -866,14 +982,25 @@
 		    fc->congestion_threshold > max_user_congthresh)
 			fc->congestion_threshold = max_user_congthresh;
 	}
+	spin_unlock(&fc->bg_lock);
 }
 
-static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
-{
-	struct fuse_init_out *arg = &req->misc.init_out;
+struct fuse_init_args {
+	struct fuse_args args;
+	struct fuse_init_in in;
+	struct fuse_init_out out;
+};
 
-	if (req->out.h.error || arg->major != FUSE_KERNEL_VERSION)
-		fc->conn_error = 1;
+static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args,
+			       int error)
+{
+	struct fuse_conn *fc = fm->fc;
+	struct fuse_init_args *ia = container_of(args, typeof(*ia), args);
+	struct fuse_init_out *arg = &ia->out;
+	bool ok = true;
+
+	if (error || arg->major != FUSE_KERNEL_VERSION)
+		ok = false;
 	else {
 		unsigned long ra_pages;
 
@@ -905,6 +1032,8 @@
 				fc->dont_mask = 1;
 			if (arg->flags & FUSE_AUTO_INVAL_DATA)
 				fc->auto_inval_data = 1;
+			else if (arg->flags & FUSE_EXPLICIT_INVAL_DATA)
+				fc->explicit_inval_data = 1;
 			if (arg->flags & FUSE_DO_READDIRPLUS) {
 				fc->do_readdirplus = 1;
 				if (arg->flags & FUSE_READDIRPLUS_AUTO)
@@ -919,66 +1048,121 @@
 			if (arg->flags & FUSE_HANDLE_KILLPRIV)
 				fc->handle_killpriv = 1;
 			if (arg->time_gran && arg->time_gran <= 1000000000)
-				fc->sb->s_time_gran = arg->time_gran;
+				fm->sb->s_time_gran = arg->time_gran;
 			if ((arg->flags & FUSE_POSIX_ACL)) {
 				fc->default_permissions = 1;
 				fc->posix_acl = 1;
-				fc->sb->s_xattr = fuse_acl_xattr_handlers;
+				fm->sb->s_xattr = fuse_acl_xattr_handlers;
 			}
+			if (arg->flags & FUSE_CACHE_SYMLINKS)
+				fc->cache_symlinks = 1;
 			if (arg->flags & FUSE_ABORT_ERROR)
 				fc->abort_err = 1;
+			if (arg->flags & FUSE_MAX_PAGES) {
+				fc->max_pages =
+					min_t(unsigned int, fc->max_pages_limit,
+					max_t(unsigned int, arg->max_pages, 1));
+			}
+			if (IS_ENABLED(CONFIG_FUSE_DAX) &&
+			    arg->flags & FUSE_MAP_ALIGNMENT &&
+			    !fuse_dax_check_alignment(fc, arg->map_alignment)) {
+				ok = false;
+			}
+			if (arg->flags & FUSE_PASSTHROUGH) {
+				fc->passthrough = 1;
+				/* Prevent further stacking */
+				fm->sb->s_stack_depth =
+					FILESYSTEM_MAX_STACK_DEPTH;
+			}
 		} else {
 			ra_pages = fc->max_read / PAGE_SIZE;
 			fc->no_lock = 1;
 			fc->no_flock = 1;
 		}
 
-		fc->sb->s_bdi->ra_pages =
-				min(fc->sb->s_bdi->ra_pages, ra_pages);
+		fm->sb->s_bdi->ra_pages =
+				min(fm->sb->s_bdi->ra_pages, ra_pages);
 		fc->minor = arg->minor;
 		fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;
 		fc->max_write = max_t(unsigned, 4096, fc->max_write);
 		fc->conn_init = 1;
 	}
+	kfree(ia);
+
+	if (!ok) {
+		fc->conn_init = 0;
+		fc->conn_error = 1;
+	}
+
 	fuse_set_initialized(fc);
 	wake_up_all(&fc->blocked_waitq);
 }
 
-static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)
+void fuse_send_init(struct fuse_mount *fm)
 {
-	struct fuse_init_in *arg = &req->misc.init_in;
+	struct fuse_init_args *ia;
 
-	arg->major = FUSE_KERNEL_VERSION;
-	arg->minor = FUSE_KERNEL_MINOR_VERSION;
-	arg->max_readahead = fc->sb->s_bdi->ra_pages * PAGE_SIZE;
-	arg->flags |= FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_ATOMIC_O_TRUNC |
+	ia = kzalloc(sizeof(*ia), GFP_KERNEL | __GFP_NOFAIL);
+
+	ia->in.major = FUSE_KERNEL_VERSION;
+	ia->in.minor = FUSE_KERNEL_MINOR_VERSION;
+	ia->in.max_readahead = fm->sb->s_bdi->ra_pages * PAGE_SIZE;
+	ia->in.flags |=
+		FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_ATOMIC_O_TRUNC |
 		FUSE_EXPORT_SUPPORT | FUSE_BIG_WRITES | FUSE_DONT_MASK |
 		FUSE_SPLICE_WRITE | FUSE_SPLICE_MOVE | FUSE_SPLICE_READ |
 		FUSE_FLOCK_LOCKS | FUSE_HAS_IOCTL_DIR | FUSE_AUTO_INVAL_DATA |
 		FUSE_DO_READDIRPLUS | FUSE_READDIRPLUS_AUTO | FUSE_ASYNC_DIO |
 		FUSE_WRITEBACK_CACHE | FUSE_NO_OPEN_SUPPORT |
 		FUSE_PARALLEL_DIROPS | FUSE_HANDLE_KILLPRIV | FUSE_POSIX_ACL |
-		FUSE_ABORT_ERROR;
-	req->in.h.opcode = FUSE_INIT;
-	req->in.numargs = 1;
-	req->in.args[0].size = sizeof(*arg);
-	req->in.args[0].value = arg;
-	req->out.numargs = 1;
+		FUSE_ABORT_ERROR | FUSE_MAX_PAGES | FUSE_CACHE_SYMLINKS |
+		FUSE_NO_OPENDIR_SUPPORT | FUSE_EXPLICIT_INVAL_DATA |
+		FUSE_PASSTHROUGH;
+#ifdef CONFIG_FUSE_DAX
+	if (fm->fc->dax)
+		ia->in.flags |= FUSE_MAP_ALIGNMENT;
+#endif
+	if (fm->fc->auto_submounts)
+		ia->in.flags |= FUSE_SUBMOUNTS;
+
+	ia->args.opcode = FUSE_INIT;
+	ia->args.in_numargs = 1;
+	ia->args.in_args[0].size = sizeof(ia->in);
+	ia->args.in_args[0].value = &ia->in;
+	ia->args.out_numargs = 1;
 	/* Variable length argument used for backward compatibility
 	   with interface version < 7.5.  Rest of init_out is zeroed
 	   by do_get_request(), so a short reply is not a problem */
-	req->out.argvar = 1;
-	req->out.args[0].size = sizeof(struct fuse_init_out);
-	req->out.args[0].value = &req->misc.init_out;
-	req->end = process_init_reply;
-	fuse_request_send_background(fc, req);
+	ia->args.out_argvar = true;
+	ia->args.out_args[0].size = sizeof(ia->out);
+	ia->args.out_args[0].value = &ia->out;
+	ia->args.force = true;
+	ia->args.nocreds = true;
+	ia->args.end = process_init_reply;
+
+	if (fuse_simple_background(fm, &ia->args, GFP_KERNEL) != 0)
+		process_init_reply(fm, &ia->args, -ENOTCONN);
+}
+EXPORT_SYMBOL_GPL(fuse_send_init);
+
+static int free_fuse_passthrough(int id, void *p, void *data)
+{
+	struct fuse_passthrough *passthrough = (struct fuse_passthrough *)p;
+
+	fuse_passthrough_release(passthrough);
+	kfree(p);
+
+	return 0;
 }
 
-static void fuse_free_conn(struct fuse_conn *fc)
+void fuse_free_conn(struct fuse_conn *fc)
 {
 	WARN_ON(!list_empty(&fc->devices));
+	idr_for_each(&fc->passthrough_req, free_fuse_passthrough, NULL);
+	idr_destroy(&fc->passthrough_req);
 	kfree_rcu(fc, rcu);
 }
+EXPORT_SYMBOL_GPL(fuse_free_conn);
 
 static int fuse_bdi_init(struct fuse_conn *fc, struct super_block *sb)
 {
@@ -999,9 +1183,9 @@
 	if (err)
 		return err;
 
-	sb->s_bdi->ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_SIZE;
 	/* fuse does it's own writeback accounting */
-	sb->s_bdi->capabilities = BDI_CAP_NO_ACCT_WB | BDI_CAP_STRICTLIMIT;
+	sb->s_bdi->capabilities &= ~BDI_CAP_WRITEBACK_ACCT;
+	sb->s_bdi->capabilities |= BDI_CAP_STRICTLIMIT;
 
 	/*
 	 * For a single fuse filesystem use max 1% of dirty +
@@ -1020,23 +1204,49 @@
 	return 0;
 }
 
-struct fuse_dev *fuse_dev_alloc(struct fuse_conn *fc)
+struct fuse_dev *fuse_dev_alloc(void)
 {
 	struct fuse_dev *fud;
+	struct list_head *pq;
 
 	fud = kzalloc(sizeof(struct fuse_dev), GFP_KERNEL);
-	if (fud) {
-		fud->fc = fuse_conn_get(fc);
-		fuse_pqueue_init(&fud->pq);
+	if (!fud)
+		return NULL;
 
-		spin_lock(&fc->lock);
-		list_add_tail(&fud->entry, &fc->devices);
-		spin_unlock(&fc->lock);
+	pq = kcalloc(FUSE_PQ_HASH_SIZE, sizeof(struct list_head), GFP_KERNEL);
+	if (!pq) {
+		kfree(fud);
+		return NULL;
 	}
+
+	fud->pq.processing = pq;
+	fuse_pqueue_init(&fud->pq);
 
 	return fud;
 }
 EXPORT_SYMBOL_GPL(fuse_dev_alloc);
+
+void fuse_dev_install(struct fuse_dev *fud, struct fuse_conn *fc)
+{
+	fud->fc = fuse_conn_get(fc);
+	spin_lock(&fc->lock);
+	list_add_tail(&fud->entry, &fc->devices);
+	spin_unlock(&fc->lock);
+}
+EXPORT_SYMBOL_GPL(fuse_dev_install);
+
+struct fuse_dev *fuse_dev_alloc_install(struct fuse_conn *fc)
+{
+	struct fuse_dev *fud;
+
+	fud = fuse_dev_alloc();
+	if (!fud)
+		return NULL;
+
+	fuse_dev_install(fud, fc);
+	return fud;
+}
+EXPORT_SYMBOL_GPL(fuse_dev_alloc_install);
 
 void fuse_dev_free(struct fuse_dev *fud)
 {
@@ -1049,41 +1259,35 @@
 
 		fuse_conn_put(fc);
 	}
+	kfree(fud->pq.processing);
 	kfree(fud);
 }
 EXPORT_SYMBOL_GPL(fuse_dev_free);
 
-static int fuse_fill_super(struct super_block *sb, void *data, int silent)
+static void fuse_fill_attr_from_inode(struct fuse_attr *attr,
+				      const struct fuse_inode *fi)
 {
-	struct fuse_dev *fud;
-	struct fuse_conn *fc;
-	struct inode *root;
-	struct fuse_mount_data d;
-	struct file *file;
-	struct dentry *root_dentry;
-	struct fuse_req *init_req;
-	int err;
-	int is_bdev = sb->s_bdev != NULL;
+	*attr = (struct fuse_attr){
+		.ino		= fi->inode.i_ino,
+		.size		= fi->inode.i_size,
+		.blocks		= fi->inode.i_blocks,
+		.atime		= fi->inode.i_atime.tv_sec,
+		.mtime		= fi->inode.i_mtime.tv_sec,
+		.ctime		= fi->inode.i_ctime.tv_sec,
+		.atimensec	= fi->inode.i_atime.tv_nsec,
+		.mtimensec	= fi->inode.i_mtime.tv_nsec,
+		.ctimensec	= fi->inode.i_ctime.tv_nsec,
+		.mode		= fi->inode.i_mode,
+		.nlink		= fi->inode.i_nlink,
+		.uid		= fi->inode.i_uid.val,
+		.gid		= fi->inode.i_gid.val,
+		.rdev		= fi->inode.i_rdev,
+		.blksize	= 1u << fi->inode.i_blkbits,
+	};
+}
 
-	err = -EINVAL;
-	if (sb->s_flags & SB_MANDLOCK)
-		goto err;
-
-	sb->s_flags &= ~(SB_NOSEC | SB_I_VERSION);
-
-	if (!parse_fuse_opt(data, &d, is_bdev, sb->s_user_ns))
-		goto err;
-
-	if (is_bdev) {
-#ifdef CONFIG_BLOCK
-		err = -EINVAL;
-		if (!sb_set_blocksize(sb, d.blksize))
-			goto err;
-#endif
-	} else {
-		sb->s_blocksize = PAGE_SIZE;
-		sb->s_blocksize_bits = PAGE_SHIFT;
-	}
+static void fuse_sb_defaults(struct super_block *sb)
+{
 	sb->s_magic = FUSE_SUPER_MAGIC;
 	sb->s_op = &fuse_super_operations;
 	sb->s_xattr = fuse_xattr_handlers;
@@ -1093,19 +1297,7 @@
 	sb->s_iflags |= SB_I_IMA_UNVERIFIABLE_SIGNATURE;
 	if (sb->s_user_ns != &init_user_ns)
 		sb->s_iflags |= SB_I_UNTRUSTED_MOUNTER;
-
-	file = fget(d.fd);
-	err = -EINVAL;
-	if (!file)
-		goto err;
-
-	/*
-	 * Require mount to happen from the same user namespace which
-	 * opened /dev/fuse to prevent potential attacks.
-	 */
-	if (file->f_op != &fuse_dev_operations ||
-	    file->f_cred->user_ns != sb->s_user_ns)
-		goto err_fput;
+	sb->s_flags &= ~(SB_NOSEC | SB_I_VERSION);
 
 	/*
 	 * If we are not in the initial user namespace posix
@@ -1113,21 +1305,89 @@
 	 */
 	if (sb->s_user_ns != &init_user_ns)
 		sb->s_xattr = fuse_no_acl_xattr_handlers;
+}
 
-	fc = kmalloc(sizeof(*fc), GFP_KERNEL);
-	err = -ENOMEM;
-	if (!fc)
-		goto err_fput;
+int fuse_fill_super_submount(struct super_block *sb,
+			     struct fuse_inode *parent_fi)
+{
+	struct fuse_mount *fm = get_fuse_mount_super(sb);
+	struct super_block *parent_sb = parent_fi->inode.i_sb;
+	struct fuse_attr root_attr;
+	struct inode *root;
 
-	fuse_conn_init(fc, sb->s_user_ns);
-	fc->release = fuse_free_conn;
+	fuse_sb_defaults(sb);
+	fm->sb = sb;
 
-	fud = fuse_dev_alloc(fc);
-	if (!fud)
-		goto err_put_conn;
+	WARN_ON(sb->s_bdi != &noop_backing_dev_info);
+	sb->s_bdi = bdi_get(parent_sb->s_bdi);
+
+	sb->s_xattr = parent_sb->s_xattr;
+	sb->s_time_gran = parent_sb->s_time_gran;
+	sb->s_blocksize = parent_sb->s_blocksize;
+	sb->s_blocksize_bits = parent_sb->s_blocksize_bits;
+	sb->s_subtype = kstrdup(parent_sb->s_subtype, GFP_KERNEL);
+	if (parent_sb->s_subtype && !sb->s_subtype)
+		return -ENOMEM;
+
+	fuse_fill_attr_from_inode(&root_attr, parent_fi);
+	root = fuse_iget(sb, parent_fi->nodeid, 0, &root_attr, 0, 0);
+	/*
+	 * This inode is just a duplicate, so it is not looked up and
+	 * its nlookup should not be incremented.  fuse_iget() does
+	 * that, though, so undo it here.
+	 */
+	get_fuse_inode(root)->nlookup--;
+	sb->s_d_op = &fuse_dentry_operations;
+	sb->s_root = d_make_root(root);
+	if (!sb->s_root)
+		return -ENOMEM;
+
+	return 0;
+}
+
+int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
+{
+	struct fuse_dev *fud = NULL;
+	struct fuse_mount *fm = get_fuse_mount_super(sb);
+	struct fuse_conn *fc = fm->fc;
+	struct inode *root;
+	struct dentry *root_dentry;
+	int err;
+
+	err = -EINVAL;
+	if (sb->s_flags & SB_MANDLOCK)
+		goto err;
+
+	fuse_sb_defaults(sb);
+
+	if (ctx->is_bdev) {
+#ifdef CONFIG_BLOCK
+		err = -EINVAL;
+		if (!sb_set_blocksize(sb, ctx->blksize))
+			goto err;
+#endif
+	} else {
+		sb->s_blocksize = PAGE_SIZE;
+		sb->s_blocksize_bits = PAGE_SHIFT;
+	}
+
+	sb->s_subtype = ctx->subtype;
+	ctx->subtype = NULL;
+	if (IS_ENABLED(CONFIG_FUSE_DAX)) {
+		err = fuse_dax_conn_alloc(fc, ctx->dax_dev);
+		if (err)
+			goto err;
+	}
+
+	if (ctx->fudptr) {
+		err = -ENOMEM;
+		fud = fuse_dev_alloc_install(fc);
+		if (!fud)
+			goto err_free_dax;
+	}
 
 	fc->dev = sb->s_dev;
-	fc->sb = sb;
+	fm->sb = sb;
 	err = fuse_bdi_init(fc, sb);
 	if (err)
 		goto err_dev_free;
@@ -1137,17 +1397,18 @@
 		fc->dont_mask = 1;
 	sb->s_flags |= SB_POSIXACL;
 
-	fc->default_permissions = d.default_permissions;
-	fc->allow_other = d.allow_other;
-	fc->user_id = d.user_id;
-	fc->group_id = d.group_id;
-	fc->max_read = max_t(unsigned, 4096, d.max_read);
-
-	/* Used by get_root_inode() */
-	sb->s_fs_info = fc;
+	fc->default_permissions = ctx->default_permissions;
+	fc->allow_other = ctx->allow_other;
+	fc->user_id = ctx->user_id;
+	fc->group_id = ctx->group_id;
+	fc->legacy_opts_show = ctx->legacy_opts_show;
+	fc->max_read = max_t(unsigned int, 4096, ctx->max_read);
+	fc->destroy = ctx->destroy;
+	fc->no_control = ctx->no_control;
+	fc->no_force_umount = ctx->no_force_umount;
 
 	err = -ENOMEM;
-	root = fuse_get_root_inode(sb, d.rootmode);
+	root = fuse_get_root_inode(sb, ctx->rootmode);
 	sb->s_d_op = &fuse_root_dentry_operations;
 	root_dentry = d_make_root(root);
 	if (!root_dentry)
@@ -1155,20 +1416,9 @@
 	/* Root dentry doesn't have .d_revalidate */
 	sb->s_d_op = &fuse_dentry_operations;
 
-	init_req = fuse_request_alloc(0);
-	if (!init_req)
-		goto err_put_root;
-	__set_bit(FR_BACKGROUND, &init_req->flags);
-
-	if (is_bdev) {
-		fc->destroy_req = fuse_request_alloc(0);
-		if (!fc->destroy_req)
-			goto err_free_init_req;
-	}
-
 	mutex_lock(&fuse_mutex);
 	err = -EINVAL;
-	if (file->private_data)
+	if (ctx->fudptr && *ctx->fudptr)
 		goto err_unlock;
 
 	err = fuse_ctl_add_conn(fc);
@@ -1177,29 +1427,77 @@
 
 	list_add_tail(&fc->entry, &fuse_conn_list);
 	sb->s_root = root_dentry;
-	file->private_data = fud;
+	if (ctx->fudptr)
+		*ctx->fudptr = fud;
 	mutex_unlock(&fuse_mutex);
+	return 0;
+
+ err_unlock:
+	mutex_unlock(&fuse_mutex);
+	dput(root_dentry);
+ err_dev_free:
+	if (fud)
+		fuse_dev_free(fud);
+ err_free_dax:
+	if (IS_ENABLED(CONFIG_FUSE_DAX))
+		fuse_dax_conn_free(fc);
+ err:
+	return err;
+}
+EXPORT_SYMBOL_GPL(fuse_fill_super_common);
+
+static int fuse_fill_super(struct super_block *sb, struct fs_context *fsc)
+{
+	struct fuse_fs_context *ctx = fsc->fs_private;
+	struct file *file;
+	int err;
+	struct fuse_conn *fc;
+	struct fuse_mount *fm;
+
+	err = -EINVAL;
+	file = fget(ctx->fd);
+	if (!file)
+		goto err;
+
+	/*
+	 * Require mount to happen from the same user namespace which
+	 * opened /dev/fuse to prevent potential attacks.
+	 */
+	if ((file->f_op != &fuse_dev_operations) ||
+	    (file->f_cred->user_ns != sb->s_user_ns))
+		goto err_fput;
+	ctx->fudptr = &file->private_data;
+
+	fc = kmalloc(sizeof(*fc), GFP_KERNEL);
+	err = -ENOMEM;
+	if (!fc)
+		goto err_fput;
+
+	fm = kzalloc(sizeof(*fm), GFP_KERNEL);
+	if (!fm) {
+		kfree(fc);
+		goto err_fput;
+	}
+
+	fuse_conn_init(fc, fm, sb->s_user_ns, &fuse_dev_fiq_ops, NULL);
+	fc->release = fuse_free_conn;
+
+	sb->s_fs_info = fm;
+
+	err = fuse_fill_super_common(sb, ctx);
+	if (err)
+		goto err_put_conn;
 	/*
 	 * atomic_dec_and_test() in fput() provides the necessary
 	 * memory barrier for file->private_data to be visible on all
 	 * CPUs after this
 	 */
 	fput(file);
-
-	fuse_send_init(fc, init_req);
-
+	fuse_send_init(get_fuse_mount_super(sb));
 	return 0;
 
- err_unlock:
-	mutex_unlock(&fuse_mutex);
- err_free_init_req:
-	fuse_request_free(init_req);
- err_put_root:
-	dput(root_dentry);
- err_dev_free:
-	fuse_dev_free(fud);
  err_put_conn:
-	fuse_conn_put(fc);
+	fuse_mount_put(fm);
 	sb->s_fs_info = NULL;
  err_fput:
 	fput(file);
@@ -1207,32 +1505,100 @@
 	return err;
 }
 
-static struct dentry *fuse_mount(struct file_system_type *fs_type,
-		       int flags, const char *dev_name,
-		       void *raw_data)
+static int fuse_get_tree(struct fs_context *fc)
 {
-	return mount_nodev(fs_type, flags, raw_data, fuse_fill_super);
+	struct fuse_fs_context *ctx = fc->fs_private;
+
+	if (!ctx->fd_present || !ctx->rootmode_present ||
+	    !ctx->user_id_present || !ctx->group_id_present)
+		return -EINVAL;
+
+#ifdef CONFIG_BLOCK
+	if (ctx->is_bdev)
+		return get_tree_bdev(fc, fuse_fill_super);
+#endif
+
+	return get_tree_nodev(fc, fuse_fill_super);
 }
 
-static void fuse_sb_destroy(struct super_block *sb)
+static const struct fs_context_operations fuse_context_ops = {
+	.free		= fuse_free_fc,
+	.parse_param	= fuse_parse_param,
+	.reconfigure	= fuse_reconfigure,
+	.get_tree	= fuse_get_tree,
+};
+
+/*
+ * Set up the filesystem mount context.
+ */
+static int fuse_init_fs_context(struct fs_context *fc)
 {
-	struct fuse_conn *fc = get_fuse_conn_super(sb);
+	struct fuse_fs_context *ctx;
 
-	if (fc) {
-		fuse_send_destroy(fc);
+	ctx = kzalloc(sizeof(struct fuse_fs_context), GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
 
-		fuse_abort_conn(fc, false);
-		fuse_wait_aborted(fc);
+	ctx->max_read = ~0;
+	ctx->blksize = FUSE_DEFAULT_BLKSIZE;
+	ctx->legacy_opts_show = true;
 
-		down_write(&fc->killsb);
-		fc->sb = NULL;
-		up_write(&fc->killsb);
+#ifdef CONFIG_BLOCK
+	if (fc->fs_type == &fuseblk_fs_type) {
+		ctx->is_bdev = true;
+		ctx->destroy = true;
+	}
+#endif
+
+	fc->fs_private = ctx;
+	fc->ops = &fuse_context_ops;
+	return 0;
+}
+
+bool fuse_mount_remove(struct fuse_mount *fm)
+{
+	struct fuse_conn *fc = fm->fc;
+	bool last = false;
+
+	down_write(&fc->killsb);
+	list_del_init(&fm->fc_entry);
+	if (list_empty(&fc->mounts))
+		last = true;
+	up_write(&fc->killsb);
+
+	return last;
+}
+EXPORT_SYMBOL_GPL(fuse_mount_remove);
+
+void fuse_conn_destroy(struct fuse_mount *fm)
+{
+	struct fuse_conn *fc = fm->fc;
+
+	if (fc->destroy)
+		fuse_send_destroy(fm);
+
+	fuse_abort_conn(fc);
+	fuse_wait_aborted(fc);
+
+	if (!list_empty(&fc->entry)) {
+		mutex_lock(&fuse_mutex);
+		list_del(&fc->entry);
+		fuse_ctl_remove_conn(fc);
+		mutex_unlock(&fuse_mutex);
 	}
 }
+EXPORT_SYMBOL_GPL(fuse_conn_destroy);
 
 static void fuse_kill_sb_anon(struct super_block *sb)
 {
-	fuse_sb_destroy(sb);
+	struct fuse_mount *fm = get_fuse_mount_super(sb);
+	bool last;
+
+	if (fm) {
+		last = fuse_mount_remove(fm);
+		if (last)
+			fuse_conn_destroy(fm);
+	}
 	kill_anon_super(sb);
 }
 
@@ -1240,29 +1606,31 @@
 	.owner		= THIS_MODULE,
 	.name		= "fuse",
 	.fs_flags	= FS_HAS_SUBTYPE | FS_USERNS_MOUNT,
-	.mount		= fuse_mount,
+	.init_fs_context = fuse_init_fs_context,
+	.parameters	= fuse_fs_parameters,
 	.kill_sb	= fuse_kill_sb_anon,
 };
 MODULE_ALIAS_FS("fuse");
 
 #ifdef CONFIG_BLOCK
-static struct dentry *fuse_mount_blk(struct file_system_type *fs_type,
-			   int flags, const char *dev_name,
-			   void *raw_data)
-{
-	return mount_bdev(fs_type, flags, dev_name, raw_data, fuse_fill_super);
-}
-
 static void fuse_kill_sb_blk(struct super_block *sb)
 {
-	fuse_sb_destroy(sb);
+	struct fuse_mount *fm = get_fuse_mount_super(sb);
+	bool last;
+
+	if (sb->s_root) {
+		last = fuse_mount_remove(fm);
+		if (last)
+			fuse_conn_destroy(fm);
+	}
 	kill_block_super(sb);
 }
 
 static struct file_system_type fuseblk_fs_type = {
 	.owner		= THIS_MODULE,
 	.name		= "fuseblk",
-	.mount		= fuse_mount_blk,
+	.init_fs_context = fuse_init_fs_context,
+	.parameters	= fuse_fs_parameters,
 	.kill_sb	= fuse_kill_sb_blk,
 	.fs_flags	= FS_REQUIRES_DEV | FS_HAS_SUBTYPE,
 };
@@ -1372,8 +1740,8 @@
 {
 	int res;
 
-	printk(KERN_INFO "fuse init (API version %i.%i)\n",
-	       FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);
+	pr_info("init (API version %i.%i)\n",
+		FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);
 
 	INIT_LIST_HEAD(&fuse_conn_list);
 	res = fuse_fs_init();
@@ -1409,7 +1777,7 @@
 
 static void __exit fuse_exit(void)
 {
-	printk(KERN_DEBUG "fuse exit\n");
+	pr_debug("exit\n");
 
 	fuse_ctl_cleanup();
 	fuse_sysfs_cleanup();

--
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