diff options
author | Tejun Heo | 2013-11-28 14:54:40 -0500 |
---|---|---|
committer | Greg Kroah-Hartman | 2013-11-29 18:10:48 -0800 |
commit | ba7443bc656e5236c316b2acacc8b551f872910f (patch) | |
tree | 08b9a7a0504ae77abc634419167958ce4e6c4e64 /fs/kernfs/dir.c | |
parent | 061447a496b915f1dc8f8c645c6825f856d2bbac (diff) |
sysfs, kernfs: implement kernfs_create/destroy_root()
There currently is single kernfs hierarchy in the whole system which
is used for sysfs. kernfs needs to support multiple hierarchies to
allow other users. This patch introduces struct kernfs_root which
serves as the root of each kernfs hierarchy and implements
kernfs_create/destroy_root().
* Each kernfs_root is associated with a root sd (sysfs_dentry). The
root is freed when the root sd is released and kernfs_destory_root()
simply invokes kernfs_remove() on the root sd. sysfs_remove_one()
is updated to handle release of the root sd. Note that ps_iattr
update in sysfs_remove_one() is trivially updated for readability.
* Root sd's are now dynamically allocated using sysfs_new_dirent().
Update sysfs_alloc_ino() so that it gives out ino from 1 so that the
root sd still gets ino 1.
* While kernfs currently only points to the root sd, it'll soon grow
fields which are specific to each hierarchy. As determining a given
sd's root will be necessary, sd->s_dir.root is added. This backlink
fits better as a separate field in sd; however, sd->s_dir is inside
union with space to spare, so use it to save space and provide
kernfs_root() accessor to determine the root sd.
* As hierarchies may be destroyed now, each mount needs to hold onto
the hierarchy it's attached to. Update sysfs_fill_super() and
sysfs_kill_sb() so that they get and put the kernfs_root
respectively.
* sysfs_root is replaced with kernfs_root which is dynamically created
by invoking kernfs_create_root() from sysfs_init().
This patch doesn't introduce any visible behavior changes.
v2: kernfs_create_root() forgot to set @sd->priv. Fixed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/kernfs/dir.c')
-rw-r--r-- | fs/kernfs/dir.c | 71 |
1 files changed, 62 insertions, 9 deletions
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index a4ca4de3cb21..246740a741ef 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -211,7 +211,7 @@ static int sysfs_alloc_ino(unsigned int *pino) retry: spin_lock(&sysfs_ino_lock); - rc = ida_get_new_above(&sysfs_ino_ida, 2, &ino); + rc = ida_get_new_above(&sysfs_ino_ida, 1, &ino); spin_unlock(&sysfs_ino_lock); if (rc == -EAGAIN) { @@ -253,9 +253,11 @@ EXPORT_SYMBOL_GPL(kernfs_get); void kernfs_put(struct sysfs_dirent *sd) { struct sysfs_dirent *parent_sd; + struct kernfs_root *root; if (!sd || !atomic_dec_and_test(&sd->s_count)) return; + root = kernfs_root(sd); repeat: /* Moving/renaming is always done while holding reference. * sd->s_parent won't change beneath us. @@ -278,8 +280,13 @@ void kernfs_put(struct sysfs_dirent *sd) kmem_cache_free(sysfs_dir_cachep, sd); sd = parent_sd; - if (sd && atomic_dec_and_test(&sd->s_count)) - goto repeat; + if (sd) { + if (atomic_dec_and_test(&sd->s_count)) + goto repeat; + } else { + /* just released the root sd, free @root too */ + kfree(root); + } } EXPORT_SYMBOL_GPL(kernfs_put); @@ -493,13 +500,15 @@ static void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, if (sd->s_flags & SYSFS_FLAG_REMOVED) return; - sysfs_unlink_sibling(sd); + if (sd->s_parent) { + sysfs_unlink_sibling(sd); - /* Update timestamps on the parent */ - ps_iattr = sd->s_parent->s_iattr; - if (ps_iattr) { - struct iattr *ps_iattrs = &ps_iattr->ia_iattr; - ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME; + /* Update timestamps on the parent */ + ps_iattr = sd->s_parent->s_iattr; + if (ps_iattr) { + ps_iattr->ia_iattr.ia_ctime = CURRENT_TIME; + ps_iattr->ia_iattr.ia_mtime = CURRENT_TIME; + } } sd->s_flags |= SYSFS_FLAG_REMOVED; @@ -604,6 +613,49 @@ struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent, EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns); /** + * kernfs_create_root - create a new kernfs hierarchy + * @priv: opaque data associated with the new directory + * + * Returns the root of the new hierarchy on success, ERR_PTR() value on + * failure. + */ +struct kernfs_root *kernfs_create_root(void *priv) +{ + struct kernfs_root *root; + struct sysfs_dirent *sd; + + root = kzalloc(sizeof(*root), GFP_KERNEL); + if (!root) + return ERR_PTR(-ENOMEM); + + sd = sysfs_new_dirent("", S_IFDIR | S_IRUGO | S_IXUGO, SYSFS_DIR); + if (!sd) { + kfree(root); + return ERR_PTR(-ENOMEM); + } + + sd->s_flags &= ~SYSFS_FLAG_REMOVED; + sd->priv = priv; + sd->s_dir.root = root; + + root->sd = sd; + + return root; +} + +/** + * kernfs_destroy_root - destroy a kernfs hierarchy + * @root: root of the hierarchy to destroy + * + * Destroy the hierarchy anchored at @root by removing all existing + * directories and destroying @root. + */ +void kernfs_destroy_root(struct kernfs_root *root) +{ + kernfs_remove(root->sd); /* will also free @root */ +} + +/** * kernfs_create_dir_ns - create a directory * @parent: parent in which to create a new directory * @name: name of the new directory @@ -626,6 +678,7 @@ struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent, if (!sd) return ERR_PTR(-ENOMEM); + sd->s_dir.root = parent->s_dir.root; sd->s_ns = ns; sd->priv = priv; |