diff options
| -rw-r--r-- | Documentation/filesystems/fuse.txt | 30 | ||||
| -rw-r--r-- | fs/fuse/Makefile | 2 | ||||
| -rw-r--r-- | fs/fuse/control.c | 218 | ||||
| -rw-r--r-- | fs/fuse/dev.c | 2 | ||||
| -rw-r--r-- | fs/fuse/fuse_i.h | 53 | ||||
| -rw-r--r-- | fs/fuse/inode.c | 141 |
6 files changed, 331 insertions, 115 deletions
diff --git a/Documentation/filesystems/fuse.txt b/Documentation/filesystems/fuse.txt index e774777..324df27 100644 --- a/Documentation/filesystems/fuse.txt +++ b/Documentation/filesystems/fuse.txt @@ -18,6 +18,14 @@ Non-privileged mount (or user mount): user. NOTE: this is not the same as mounts allowed with the "user" option in /etc/fstab, which is not discussed here. +Filesystem connection: + + A connection between the filesystem daemon and the kernel. The + connection exists until either the daemon dies, or the filesystem is + umounted. Note that detaching (or lazy umounting) the filesystem + does _not_ break the connection, in this case it will exist until + the last reference to the filesystem is released. + Mount owner: The user who does the mounting. @@ -86,16 +94,20 @@ Mount options The default is infinite. Note that the size of read requests is limited anyway to 32 pages (which is 128kbyte on i386). -Sysfs -~~~~~ +Control filesystem +~~~~~~~~~~~~~~~~~~ + +There's a control filesystem for FUSE, which can be mounted by: -FUSE sets up the following hierarchy in sysfs: + mount -t fusectl none /sys/fs/fuse/connections - /sys/fs/fuse/connections/N/ +Mounting it under the '/sys/fs/fuse/connections' directory makes it +backwards compatible with earlier versions. -where N is an increasing number allocated to each new connection. +Under the fuse control filesystem each connection has a directory +named by a unique number. -For each connection the following attributes are defined: +For each connection the following files exist within this directory: 'waiting' @@ -110,7 +122,7 @@ For each connection the following attributes are defined: connection. This means that all waiting requests will be aborted an error returned for all aborted and new requests. -Only a privileged user may read or write these attributes. +Only the owner of the mount may read or write these files. Aborting a filesystem connection ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ @@ -139,8 +151,8 @@ the filesystem. There are several ways to do this: - Use forced umount (umount -f). Works in all cases but only if filesystem is still attached (it hasn't been lazy unmounted) - - Abort filesystem through the sysfs interface. Most powerful - method, always works. + - Abort filesystem through the FUSE control filesystem. Most + powerful method, always works. How do non-privileged mounts work? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ diff --git a/fs/fuse/Makefile b/fs/fuse/Makefile index c3e1f76..7243706 100644 --- a/fs/fuse/Makefile +++ b/fs/fuse/Makefile @@ -4,4 +4,4 @@ obj-$(CONFIG_FUSE_FS) += fuse.o -fuse-objs := dev.o dir.o file.o inode.o +fuse-objs := dev.o dir.o file.o inode.o control.o diff --git a/fs/fuse/control.c b/fs/fuse/control.c new file mode 100644 index 0000000..a3bce3a --- /dev/null +++ b/fs/fuse/control.c @@ -0,0 +1,218 @@ +/* + FUSE: Filesystem in Userspace + Copyright (C) 2001-2006 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/init.h> +#include <linux/module.h> + +#define FUSE_CTL_SUPER_MAGIC 0x65735543 + +/* + * This is non-NULL when the single instance of the control filesystem + * exists. Protected by fuse_mutex + */ +static struct super_block *fuse_control_sb; + +static struct fuse_conn *fuse_ctl_file_conn_get(struct file *file) +{ + struct fuse_conn *fc; + mutex_lock(&fuse_mutex); + fc = file->f_dentry->d_inode->u.generic_ip; + if (fc) + fc = fuse_conn_get(fc); + mutex_unlock(&fuse_mutex); + return fc; +} + +static ssize_t fuse_conn_abort_write(struct file *file, const char __user *buf, + size_t count, loff_t *ppos) +{ + struct fuse_conn *fc = fuse_ctl_file_conn_get(file); + if (fc) { + fuse_abort_conn(fc); + fuse_conn_put(fc); + } + return count; +} + +static ssize_t fuse_conn_waiting_read(struct file *file, char __user *buf, + size_t len, loff_t *ppos) +{ + char tmp[32]; + size_t size; + + if (!*ppos) { + struct fuse_conn *fc = fuse_ctl_file_conn_get(file); + if (!fc) + return 0; + + file->private_data=(void *)(long)atomic_read(&fc->num_waiting); + fuse_conn_put(fc); + } + size = sprintf(tmp, "%ld\n", (long)file->private_data); + return simple_read_from_buffer(buf, len, ppos, tmp, size); +} + +static const struct file_operations fuse_ctl_abort_ops = { + .open = nonseekable_open, + .write = fuse_conn_abort_write, +}; + +static const struct file_operations fuse_ctl_waiting_ops = { + .open = nonseekable_open, + .read = fuse_conn_waiting_read, +}; + +static struct dentry *fuse_ctl_add_dentry(struct dentry *parent, + struct fuse_conn *fc, + const char *name, + int mode, int nlink, + struct inode_operations *iop, + const struct file_operations *fop) +{ + struct dentry *dentry; + struct inode *inode; + + BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES); + dentry = d_alloc_name(parent, name); + if (!dentry) + return NULL; + + fc->ctl_dentry[fc->ctl_ndents++] = dentry; + inode = new_inode(fuse_control_sb); + if (!inode) + return NULL; + + inode->i_mode = mode; + inode->i_uid = fc->user_id; + inode->i_gid = fc->group_id; + inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; + /* setting ->i_op to NULL is not allowed */ + if (iop) + inode->i_op = iop; + inode->i_fop = fop; + inode->i_nlink = nlink; + inode->u.generic_ip = fc; + d_add(dentry, inode); + return dentry; +} + +/* + * Add a connection to the control filesystem (if it exists). Caller + * must host fuse_mutex + */ +int fuse_ctl_add_conn(struct fuse_conn *fc) +{ + struct dentry *parent; + char name[32]; + + if (!fuse_control_sb) + return 0; + + parent = fuse_control_sb->s_root; + parent->d_inode->i_nlink++; + sprintf(name, "%llu", (unsigned long long) fc->id); + parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR | 0500, 2, + &simple_dir_inode_operations, + &simple_dir_operations); + if (!parent) + goto err; + + if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG | 0400, 1, + NULL, &fuse_ctl_waiting_ops) || + !fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG | 0200, 1, + NULL, &fuse_ctl_abort_ops)) + goto err; + + return 0; + + err: + fuse_ctl_remove_conn(fc); + return -ENOMEM; +} + +/* + * Remove a connection from the control filesystem (if it exists). + * Caller must host fuse_mutex + */ +void fuse_ctl_remove_conn(struct fuse_conn *fc) +{ + int i; + + if (!fuse_control_sb) + return; + + for (i = fc->ctl_ndents - 1; i >= 0; i--) { + struct dentry *dentry = fc->ctl_dentry[i]; + dentry->d_inode->u.generic_ip = NULL; + d_drop(dentry); + dput(dentry); + } + fuse_control_sb->s_root->d_inode->i_nlink--; +} + +static int fuse_ctl_fill_super(struct super_block *sb, void *data, int silent) +{ + struct tree_descr empty_descr = {""}; + struct fuse_conn *fc; + int err; + + err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr); + if (err) + return err; + + mutex_lock(&fuse_mutex); + BUG_ON(fuse_control_sb); + fuse_control_sb = sb; + list_for_each_entry(fc, &fuse_conn_list, entry) { + err = fuse_ctl_add_conn(fc); + if (err) { + fuse_control_sb = NULL; + mutex_unlock(&fuse_mutex); + return err; + } + } + mutex_unlock(&fuse_mutex); + + return 0; +} + +static int fuse_ctl_get_sb(struct file_system_type *fs_type, int flags, + const char *dev_name, void *raw_data, + struct vfsmount *mnt) +{ + return get_sb_single(fs_type, flags, raw_data, + fuse_ctl_fill_super, mnt); +} + +static void fuse_ctl_kill_sb(struct super_block *sb) +{ + mutex_lock(&fuse_mutex); + fuse_control_sb = NULL; + mutex_unlock(&fuse_mutex); + + kill_litter_super(sb); +} + +static struct file_system_type fuse_ctl_fs_type = { + .owner = THIS_MODULE, + .name = "fusectl", + .get_sb = fuse_ctl_get_sb, + .kill_sb = fuse_ctl_kill_sb, +}; + +int __init fuse_ctl_init(void) +{ + return register_filesystem(&fuse_ctl_fs_type); +} + +void fuse_ctl_cleanup(void) +{ + unregister_filesystem(&fuse_ctl_fs_type); +} diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index fec4779..fe3adf5 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -833,7 +833,7 @@ static int fuse_dev_release(struct inode *inode, struct file *file) end_requests(fc, &fc->processing); spin_unlock(&fc->lock); fasync_helper(-1, file, 0, &fc->fasync); - kobject_put(&fc->kobj); + fuse_conn_put(fc); } return 0; diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 25f8581..ac12b01 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -14,6 +14,7 @@ #include <linux/spinlock.h> #include <linux/mm.h> #include <linux/backing-dev.h> +#include <linux/mutex.h> /** Max number of pages that can be used in a single read request */ #define FUSE_MAX_PAGES_PER_REQ 32 @@ -24,6 +25,9 @@ /** It could be as large as PATH_MAX, but would that have any uses? */ #define FUSE_NAME_MAX 1024 +/** Number of dentries for each connection in the control filesystem */ +#define FUSE_CTL_NUM_DENTRIES 3 + /** If the FUSE_DEFAULT_PERMISSIONS flag is given, the filesystem module will check permissions based on the file mode. Otherwise no permission checking is done in the kernel */ @@ -33,6 +37,11 @@ doing the mount will be allowed to access the filesystem */ #define FUSE_ALLOW_OTHER (1 << 1) +/** List of active connections */ +extern struct list_head fuse_conn_list; + +/** Global mutex protecting fuse_conn_list and the control filesystem */ +extern struct mutex fuse_mutex; /** FUSE inode */ struct fuse_inode { @@ -216,6 +225,9 @@ struct fuse_conn { /** Lock protecting accessess to members of this structure */ spinlock_t lock; + /** Refcount */ + atomic_t count; + /** The user id for this mount */ uid_t user_id; @@ -310,8 +322,17 @@ struct fuse_conn { /** Backing dev info */ struct backing_dev_info bdi; - /** kobject */ - struct kobject kobj; + /** Entry on the fuse_conn_list */ + struct list_head entry; + + /** Unique ID */ + u64 id; + + /** Dentries in the control filesystem */ + struct dentry *ctl_dentry[FUSE_CTL_NUM_DENTRIES]; + + /** number of dentries used in the above array */ + int ctl_ndents; /** O_ASYNC requests */ struct fasync_struct *fasync; @@ -327,11 +348,6 @@ static inline struct fuse_conn *get_fuse_conn(struct inode *inode) return get_fuse_conn_super(inode->i_sb); } -static inline struct fuse_conn *get_fuse_conn_kobj(struct kobject *obj) -{ - return container_of(obj, struct fuse_conn, kobj); -} - static inline struct fuse_inode *get_fuse_inode(struct inode *inode) { return container_of(inode, struct fuse_inode, inode); @@ -422,6 +438,9 @@ int fuse_dev_init(void); */ void fuse_dev_cleanup(void); +int fuse_ctl_init(void); +void fuse_ctl_cleanup(void); + /** * Allocate a request */ @@ -470,3 +489,23 @@ int fuse_do_getattr(struct inode *inode); * Invalidate inode attributes */ void fuse_invalidate_attr(struct inode *inode); + +/** + * Acquire reference to fuse_conn + */ +struct fuse_conn *fuse_conn_get(struct fuse_conn *fc); + +/** + * Release reference to fuse_conn + */ +void fuse_conn_put(struct fuse_conn *fc); + +/** + * Add connection to control filesystem + */ +int fuse_ctl_add_conn(struct fuse_conn *fc); + +/** + * Remove connection from control filesystem + */ +void fuse_ctl_remove_conn(struct fuse_conn *fc); diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index 0225729..13a7e8a 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -22,13 +22,8 @@ MODULE_DESCRIPTION("Filesystem in Userspace"); MODULE_LICENSE("GPL"); static kmem_cache_t *fuse_inode_cachep; -static struct subsystem connections_subsys; - -struct fuse_conn_attr { - struct attribute attr; - ssize_t (*show)(struct fuse_conn *, char *); - ssize_t (*store)(struct fuse_conn *, const char *, size_t); -}; +struct list_head fuse_conn_list; +DEFINE_MUTEX(fuse_mutex); #define FUSE_SUPER_MAGIC 0x65735546 @@ -211,8 +206,11 @@ static void fuse_put_super(struct super_block *sb) kill_fasync(&fc->fasync, SIGIO, POLL_IN); wake_up_all(&fc->waitq); wake_up_all(&fc->blocked_waitq); - kobject_del(&fc->kobj); - kobject_put(&fc->kobj); + mutex_lock(&fuse_mutex); + list_del(&fc->entry); + fuse_ctl_remove_conn(fc); + mutex_unlock(&fuse_mutex); + fuse_conn_put(fc); } static void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatfs *attr) @@ -362,11 +360,6 @@ static int fuse_show_options(struct seq_file *m, struct vfsmount *mnt) return 0; } -static void fuse_conn_release(struct kobject *kobj) -{ - kfree(get_fuse_conn_kobj(kobj)); -} - static struct fuse_conn *new_conn(void) { struct fuse_conn *fc; @@ -374,13 +367,12 @@ static struct fuse_conn *new_conn(void) fc = kzalloc(sizeof(*fc), GFP_KERNEL); if (fc) { spin_lock_init(&fc->lock); + atomic_set(&fc->count, 1); init_waitqueue_head(&fc->waitq); init_waitqueue_head(&fc->blocked_waitq); INIT_LIST_HEAD(&fc->pending); INIT_LIST_HEAD(&fc->processing); INIT_LIST_HEAD(&fc->io); - kobj_set_kset_s(fc, connections_subsys); - kobject_init(&fc->kobj); atomic_set(&fc->num_waiting, 0); fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; fc->bdi.unplug_io_fn = default_unplug_io_fn; @@ -390,6 +382,18 @@ static struct fuse_conn *new_conn(void) return fc; } +void fuse_conn_put(struct fuse_conn *fc) +{ + if (atomic_dec_and_test(&fc->count)) + kfree(fc); +} + +struct fuse_conn *fuse_conn_get(struct fuse_conn *fc) +{ + atomic_inc(&fc->count); + return fc; +} + static struct inode *get_root_inode(struct super_block *sb, unsigned mode) { struct fuse_attr attr; @@ -459,10 +463,9 @@ static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req) request_send_background(fc, req); } -static unsigned long long conn_id(void) +static u64 conn_id(void) { - /* BKL is held for ->get_sb() */ - static unsigned long long ctr = 1; + static u64 ctr = 1; return ctr++; } @@ -519,24 +522,21 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent) if (!init_req) goto err_put_root; - err = kobject_set_name(&fc->kobj, "%llu", conn_id()); - if (err) - goto err_free_req; - - err = kobject_add(&fc->kobj); - if (err) - goto err_free_req; - - /* Setting file->private_data can't race with other mount() - instances, since BKL is held for ->get_sb() */ + mutex_lock(&fuse_mutex); err = -EINVAL; if (file->private_data) - goto err_kobject_del; + goto err_unlock; + fc->id = conn_id(); + err = fuse_ctl_add_conn(fc); + if (err) + goto err_unlock; + + list_add_tail(&fc->entry, &fuse_conn_list); sb->s_root = root_dentry; fc->connected = 1; - kobject_get(&fc->kobj); - file->private_data = fc; + file->private_data = fuse_conn_get(fc); + mutex_unlock(&fuse_mutex); /* * atomic_dec_and_test() in fput() provides the necessary * memory barrier for file->private_data to be visible on all @@ -548,15 +548,14 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent) return 0; - err_kobject_del: - kobject_del(&fc->kobj); - err_free_req: + err_unlock: + mutex_unlock(&fuse_mutex); fuse_request_free(init_req); err_put_root: dput(root_dentry); err: fput(file); - kobject_put(&fc->kobj); + fuse_conn_put(fc); return err; } @@ -574,68 +573,8 @@ static struct file_system_type fuse_fs_type = { .kill_sb = kill_anon_super, }; -static ssize_t fuse_conn_waiting_show(struct fuse_conn *fc, char *page) -{ - return sprintf(page, "%i\n", atomic_read(&fc->num_waiting)); -} - -static ssize_t fuse_conn_abort_store(struct fuse_conn *fc, const char *page, - size_t count) -{ - fuse_abort_conn(fc); - return count; -} - -static struct fuse_conn_attr fuse_conn_waiting = - __ATTR(waiting, 0400, fuse_conn_waiting_show, NULL); -static struct fuse_conn_attr fuse_conn_abort = - __ATTR(abort, 0600, NULL, fuse_conn_abort_store); - -static struct attribute *fuse_conn_attrs[] = { - &fuse_conn_waiting.attr, - &fuse_conn_abort.attr, - NULL, -}; - -static ssize_t fuse_conn_attr_show(struct kobject *kobj, - struct attribute *attr, - char *page) -{ - struct fuse_conn_attr *fca = - container_of(attr, struct fuse_conn_attr, attr); - - if (fca->show) - return fca->show(get_fuse_conn_kobj(kobj), page); - else - return -EACCES; -} - -static ssize_t fuse_conn_attr_store(struct kobject *kobj, - struct attribute *attr, - const char *page, size_t count) -{ - struct fuse_conn_attr *fca = - container_of(attr, struct fuse_conn_attr, attr); - - if (fca->store) - return fca->store(get_fuse_conn_kobj(kobj), page, count); - else - return -EACCES; -} - -static struct sysfs_ops fuse_conn_sysfs_ops = { - .show = &fuse_conn_attr_show, - .store = &fuse_conn_attr_store, -}; - -static struct kobj_type ktype_fuse_conn = { - .release = fuse_conn_release, - .sysfs_ops = &fuse_conn_sysfs_ops, - .default_attrs = fuse_conn_attrs, -}; - static decl_subsys(fuse, NULL, NULL); -static decl_subsys(connections, &ktype_fuse_conn, NULL); +static decl_subsys(connections, NULL, NULL); static void fuse_inode_init_once(void *foo, kmem_cache_t *cachep, unsigned long flags) @@ -709,6 +648,7 @@ static int __init fuse_init(void) printk("fuse init (API version %i.%i)\n", FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION); + INIT_LIST_HEAD(&fuse_conn_list); res = fuse_fs_init(); if (res) goto err; @@ -721,8 +661,14 @@ static int __init fuse_init(void) if (res) goto err_dev_cleanup; + res = fuse_ctl_init(); + if (res) + goto err_sysfs_cleanup; + return 0; + err_sysfs_cleanup: + fuse_sysfs_cleanup(); err_dev_cleanup: fuse_dev_cleanup(); err_fs_cleanup: @@ -735,6 +681,7 @@ static void __exit fuse_exit(void) { printk(KERN_DEBUG "fuse exit\n"); + fuse_ctl_cleanup(); fuse_sysfs_cleanup(); fuse_fs_cleanup(); fuse_dev_cleanup(); |
