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author | Olof Johansson <olof@lixom.net> | 2014-07-19 15:03:08 -0700 |
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committer | Olof Johansson <olof@lixom.net> | 2014-07-19 15:03:08 -0700 |
commit | f37ac9e5a47d72eab5185b0ddc14dfc943cc9589 (patch) | |
tree | 53577aa529e3bbe718459d0626fc6d45ada3dcdd /fs/kernfs/mount.c | |
parent | 4338925434e4bf5ff714055713f3fb9b5fae9037 (diff) | |
parent | fc2cac41ebbfb16da8b036cba6ec6714ab780a6d (diff) | |
download | linux-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.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", |