[PATCH] fuse: make fuse connection a kobject

Kobjectify fuse_conn, and make it visible under /sys/fs/fuse/connections.

Lacking any natural naming, connections are numbered.

This patch doesn't add any attributes, just the infrastructure.

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 164 insertions, 43 deletions

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 5cd43bf917a4..de4a0a0bda8a 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -852,9 +852,11 @@ static int fuse_dev_release(struct inode *inode, struct file *file)
                 fc->connected = 0;
                 end_requests(fc, &fc->pending);
                 end_requests(fc, &fc->processing);
-                fuse_release_conn(fc);
         }
         spin_unlock(&fuse_lock);
+        if (fc)
+                kobject_put(&fc->kobj);
+
         return 0;
 }
 
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index e824a09d3151..6ef1e5f5873b 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -196,9 +196,6 @@ struct fuse_req {
  * unmounted.
  */
 struct fuse_conn {
-        /** Reference count */
-        int count;
-
         /** The user id for this mount */
         uid_t user_id;
 
@@ -288,6 +285,9 @@ struct fuse_conn {
 
         /** Backing dev info */
         struct backing_dev_info bdi;
+
+        /** kobject */
+        struct kobject kobj;
 };
 
 static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
@@ -300,6 +300,11 @@ 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);
@@ -400,12 +405,6 @@ void fuse_init_symlink(struct inode *inode);
 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr);
 
 /**
- * Check if the connection can be released, and if yes, then free the
- * connection structure
- */
-void fuse_release_conn(struct fuse_conn *fc);
-
-/**
  * Initialize the client device
  */
 int fuse_dev_init(void);
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index d6a09fdaa941..514b700c863d 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -24,6 +24,13 @@ MODULE_LICENSE("GPL");
 
 spinlock_t fuse_lock;
 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);
+};
 
 #define FUSE_SUPER_MAGIC 0x65735546
 
@@ -201,11 +208,12 @@ static void fuse_put_super(struct super_block *sb)
         spin_lock(&fuse_lock);
         fc->mounted = 0;
         fc->connected = 0;
+        spin_unlock(&fuse_lock);
+        up_write(&fc->sbput_sem);
         /* Flush all readers on this fs */
         wake_up_all(&fc->waitq);
-        up_write(&fc->sbput_sem);
-        fuse_release_conn(fc);
-        spin_unlock(&fuse_lock);
+        kobject_del(&fc->kobj);
+        kobject_put(&fc->kobj);
 }
 
 static void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatfs *attr)
@@ -354,8 +362,10 @@ static int fuse_show_options(struct seq_file *m, struct vfsmount *mnt)
         return 0;
 }
 
-static void free_conn(struct fuse_conn *fc)
+static void fuse_conn_release(struct kobject *kobj)
 {
+        struct fuse_conn *fc = get_fuse_conn_kobj(kobj);
+
         while (!list_empty(&fc->unused_list)) {
                 struct fuse_req *req;
                 req = list_entry(fc->unused_list.next, struct fuse_req, list);
@@ -365,20 +375,12 @@ static void free_conn(struct fuse_conn *fc)
         kfree(fc);
 }
 
-/* Must be called with the fuse lock held */
-void fuse_release_conn(struct fuse_conn *fc)
-{
-        fc->count--;
-        if (!fc->count)
-                free_conn(fc);
-}
-
 static struct fuse_conn *new_conn(void)
 {
         struct fuse_conn *fc;
 
         fc = kzalloc(sizeof(*fc), GFP_KERNEL);
-        if (fc != NULL) {
+        if (fc) {
                 int i;
                 init_waitqueue_head(&fc->waitq);
                 INIT_LIST_HEAD(&fc->pending);
@@ -388,10 +390,12 @@ static struct fuse_conn *new_conn(void)
                 INIT_LIST_HEAD(&fc->background);
                 sema_init(&fc->outstanding_sem, 1); /* One for INIT */
                 init_rwsem(&fc->sbput_sem);
+                kobj_set_kset_s(fc, connections_subsys);
+                kobject_init(&fc->kobj);
                 for (i = 0; i < FUSE_MAX_OUTSTANDING; i++) {
                         struct fuse_req *req = fuse_request_alloc();
                         if (!req) {
-                                free_conn(fc);
+                                kobject_put(&fc->kobj);
                                 return NULL;
                         }
                         list_add(&req->list, &fc->unused_list);
@@ -406,25 +410,32 @@ static struct fuse_conn *new_conn(void)
 static struct fuse_conn *get_conn(struct file *file, struct super_block *sb)
 {
         struct fuse_conn *fc;
+        int err;
 
+        err = -EINVAL;
         if (file->f_op != &fuse_dev_operations)
-                return ERR_PTR(-EINVAL);
+                goto out_err;
+
+        err = -ENOMEM;
         fc = new_conn();
-        if (fc == NULL)
-                return ERR_PTR(-ENOMEM);
+        if (!fc)
+                goto out_err;
+
         spin_lock(&fuse_lock);
-        if (file->private_data) {
-                free_conn(fc);
-                fc = ERR_PTR(-EINVAL);
-        } else {
-                file->private_data = fc;
-                sb->s_fs_info = fc;
-                fc->mounted = 1;
-                fc->connected = 1;
-                fc->count = 2;
-        }
+        err = -EINVAL;
+        if (file->private_data)
+                goto out_unlock;
+
+        kobject_get(&fc->kobj);
+        file->private_data = fc;
         spin_unlock(&fuse_lock);
         return fc;
+
+ out_unlock:
+        spin_unlock(&fuse_lock);
+        kobject_put(&fc->kobj);
+ out_err:
+        return ERR_PTR(err);
 }
 
 static struct inode *get_root_inode(struct super_block *sb, unsigned mode)
@@ -447,12 +458,23 @@ static struct super_operations fuse_super_operations = {
         .show_options   = fuse_show_options,
 };
 
+static unsigned long long conn_id(void)
+{
+        static unsigned long long ctr = 1;
+        unsigned long long val;
+        spin_lock(&fuse_lock);
+        val = ctr++;
+        spin_unlock(&fuse_lock);
+        return val;
+}
+
 static int fuse_fill_super(struct super_block *sb, void *data, int silent)
 {
         struct fuse_conn *fc;
         struct inode *root;
         struct fuse_mount_data d;
         struct file *file;
+        struct dentry *root_dentry;
         int err;
 
         if (!parse_fuse_opt((char *) data, &d))
@@ -480,23 +502,42 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent)
         if (fc->max_read / PAGE_CACHE_SIZE < fc->bdi.ra_pages)
                 fc->bdi.ra_pages = fc->max_read / PAGE_CACHE_SIZE;
 
+        /* Used by get_root_inode() */
+        sb->s_fs_info = fc;
+
         err = -ENOMEM;
         root = get_root_inode(sb, d.rootmode);
-        if (root == NULL)
+        if (!root)
                 goto err;
 
-        sb->s_root = d_alloc_root(root);
-        if (!sb->s_root) {
+        root_dentry = d_alloc_root(root);
+        if (!root_dentry) {
                 iput(root);
                 goto err;
         }
+
+        err = kobject_set_name(&fc->kobj, "%llu", conn_id());
+        if (err)
+                goto err_put_root;
+
+        err = kobject_add(&fc->kobj);
+        if (err)
+                goto err_put_root;
+
+        sb->s_root = root_dentry;
+        spin_lock(&fuse_lock);
+        fc->mounted = 1;
+        fc->connected = 1;
+        spin_unlock(&fuse_lock);
+
         fuse_send_init(fc);
+
         return 0;
 
+ err_put_root:
+        dput(root_dentry);
  err:
-        spin_lock(&fuse_lock);
-        fuse_release_conn(fc);
-        spin_unlock(&fuse_lock);
+        kobject_put(&fc->kobj);
         return err;
 }
 
@@ -514,6 +555,50 @@ static struct file_system_type fuse_fs_type = {
         .kill_sb        = kill_anon_super,
 };
 
+static struct attribute *fuse_conn_attrs[] = {
+        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 void fuse_inode_init_once(void *foo, kmem_cache_t *cachep,
                                  unsigned long flags)
 {
@@ -551,6 +636,34 @@ static void fuse_fs_cleanup(void)
         kmem_cache_destroy(fuse_inode_cachep);
 }
 
+static int fuse_sysfs_init(void)
+{
+        int err;
+
+        kset_set_kset_s(&fuse_subsys, fs_subsys);
+        err = subsystem_register(&fuse_subsys);
+        if (err)
+                goto out_err;
+
+        kset_set_kset_s(&connections_subsys, fuse_subsys);
+        err = subsystem_register(&connections_subsys);
+        if (err)
+                goto out_fuse_unregister;
+
+        return 0;
+
+ out_fuse_unregister:
+        subsystem_unregister(&fuse_subsys);
+ out_err:
+        return err;
+}
+
+static void fuse_sysfs_cleanup(void)
+{
+        subsystem_unregister(&connections_subsys);
+        subsystem_unregister(&fuse_subsys);
+}
+
 static int __init fuse_init(void)
 {
         int res;
@@ -567,8 +680,14 @@ static int __init fuse_init(void)
         if (res)
                 goto err_fs_cleanup;
 
+        res = fuse_sysfs_init();
+        if (res)
+                goto err_dev_cleanup;
+
         return 0;
 
+ err_dev_cleanup:
+        fuse_dev_cleanup();
  err_fs_cleanup:
         fuse_fs_cleanup();
  err:
@@ -579,6 +698,7 @@ static void __exit fuse_exit(void)
 {
         printk(KERN_DEBUG "fuse exit\n");
 
+        fuse_sysfs_cleanup();
         fuse_fs_cleanup();
         fuse_dev_cleanup();
 }