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authorOlof Johansson <olof@lixom.net>2014-07-19 15:03:08 -0700
committerOlof Johansson <olof@lixom.net>2014-07-19 15:03:08 -0700
commitf37ac9e5a47d72eab5185b0ddc14dfc943cc9589 (patch)
tree53577aa529e3bbe718459d0626fc6d45ada3dcdd /fs/kernfs/mount.c
parent4338925434e4bf5ff714055713f3fb9b5fae9037 (diff)
parentfc2cac41ebbfb16da8b036cba6ec6714ab780a6d (diff)
downloadlinux-f37ac9e5a47d72eab5185b0ddc14dfc943cc9589.tar.bz2
Merge tag 'exynos-cpuidle' of git://git.kernel.org/pub/scm/linux/kernel/git/kgene/linux-samsung into next/soc
Merge "Samsung exynos cpuidle update for v3.17" from Kukjin Kim: - add callbacks exynos_suspend() and exynos_powered_up() for support cpuidle through mcpm - skip exynos_cpuidle for exynos5420 because is uses cpuidle-big-liggle generic cpuidle driver - add generic functions to calculate cpu number is used for pmu and this is required for exynos5420 multi-cluster - add of_device_id structure for big.LITTLE cpuidle and add "samsung,exynos5420" compatible string for exynos5420 * tag 'exynos-cpuidle' of git://git.kernel.org/pub/scm/linux/kernel/git/kgene/linux-samsung: ARM: EXYNOS: populate suspend and powered_up callbacks for mcpm ARM: EXYNOS: do not allow cpuidle registration for exynos5420 cpuidle: big.LITTLE: init driver for exynos5420 cpuidle: big.LITTLE: Add ARCH_EXYNOS entry in config ARM: EXYNOS: add generic function to calculate cpu number cpuidle: big.LITTLE: add of_device_id structure + Linux 3.16-rc5 Signed-off-by: Olof Johansson <olof@lixom.net>
Diffstat (limited to 'fs/kernfs/mount.c')
-rw-r--r--fs/kernfs/mount.c30
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",