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author | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-07-21 10:07:25 -0700 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-07-21 10:07:25 -0700 |
commit | 90125edbc49ec58b9101c4271bb1d87b04a4620f (patch) | |
tree | 068353d4234435b17ade687b50a5d5015bdf1ad9 /fs/kernfs | |
parent | 0a8adf584759cbcbce5d88d419db01a8d0373abf (diff) | |
parent | 9a3c4145af32125c5ee39c0272662b47307a8323 (diff) |
Merge 3.16-rc6 into driver-core-next
We want the platform changes in here as well.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/kernfs')
-rw-r--r-- | fs/kernfs/mount.c | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c index d171b98a6cdd..f973ae9b05f1 100644 --- a/fs/kernfs/mount.c +++ b/fs/kernfs/mount.c @@ -211,6 +211,36 @@ void kernfs_kill_sb(struct super_block *sb) kernfs_put(root_kn); } +/** + * kernfs_pin_sb: try to pin the superblock associated with a kernfs_root + * @kernfs_root: the kernfs_root in question + * @ns: the namespace tag + * + * Pin the superblock so the superblock won't be destroyed in subsequent + * operations. This can be used to block ->kill_sb() which may be useful + * for kernfs users which dynamically manage superblocks. + * + * Returns NULL if there's no superblock associated to this kernfs_root, or + * -EINVAL if the superblock is being freed. + */ +struct super_block *kernfs_pin_sb(struct kernfs_root *root, const void *ns) +{ + struct kernfs_super_info *info; + struct super_block *sb = NULL; + + mutex_lock(&kernfs_mutex); + list_for_each_entry(info, &root->supers, node) { + if (info->ns == ns) { + sb = info->sb; + if (!atomic_inc_not_zero(&info->sb->s_active)) + sb = ERR_PTR(-EINVAL); + break; + } + } + mutex_unlock(&kernfs_mutex); + return sb; +} + void __init kernfs_init(void) { kernfs_node_cache = kmem_cache_create("kernfs_node_cache", |