diff options
author | Tejun Heo <tj@kernel.org> | 2013-11-30 02:18:32 +0400 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-11-30 06:21:01 +0400 |
commit | cf9e5a73aaff0204801dd19cb4bd91d32f32026a (patch) | |
tree | 4a63d030a4c2ee08c06b97d348bcf42bdf7a3cd4 /include/linux | |
parent | fa736a951e456b996a76826ba78ff974414c3b55 (diff) | |
download | linux-cf9e5a73aaff0204801dd19cb4bd91d32f32026a.tar.xz |
sysfs, kernfs: make sysfs_dirent definition public
sysfs_dirent includes some information which should be available to
kernfs users - the type, flags, name and parent pointer. This patch
moves sysfs_dirent definition from kernfs/kernfs-internal.h to
include/linux/kernfs.h so that kernfs users can access them.
The type part of flags is exported as enum kernfs_node_type, the flags
kernfs_node_flag, sysfs_type() and kernfs_enable_ns() are moved to
include/linux/kernfs.h and the former is updated to return the enum
type. sysfs_dirent->s_parent and ->s_name are marked explicitly as
public.
This patch doesn't introduce any functional changes.
v2: Flags exported too and kernfs_enable_ns() definition moved.
v3: While moving kernfs_enable_ns() to include/linux/kernfs.h, v1 and
v2 put the definition outside CONFIG_SYSFS replacing the dummy
implementation with the actual implementation too. Unfortunately,
this can lead to oops when !CONFIG_SYSFS because
kernfs_enable_ns() may be called on a NULL @sd and now tries to
dereference @sd instead of not doing anything. This issue was
reported by Yuanhan Liu.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux')
-rw-r--r-- | include/linux/kernfs.h | 118 |
1 files changed, 114 insertions, 4 deletions
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index 75fcbe5c9d65..faaf4f29e33d 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -13,6 +13,9 @@ #include <linux/mutex.h> #include <linux/idr.h> #include <linux/lockdep.h> +#include <linux/rbtree.h> +#include <linux/atomic.h> +#include <linux/completion.h> struct file; struct iattr; @@ -21,7 +24,92 @@ struct vm_area_struct; struct super_block; struct file_system_type; -struct sysfs_dirent; +struct sysfs_open_dirent; +struct sysfs_inode_attrs; + +enum kernfs_node_type { + SYSFS_DIR = 0x0001, + SYSFS_KOBJ_ATTR = 0x0002, + SYSFS_KOBJ_LINK = 0x0004, +}; + +#define SYSFS_TYPE_MASK 0x000f +#define SYSFS_COPY_NAME (SYSFS_DIR | SYSFS_KOBJ_LINK) +#define SYSFS_ACTIVE_REF SYSFS_KOBJ_ATTR +#define SYSFS_FLAG_MASK ~SYSFS_TYPE_MASK + +enum kernfs_node_flag { + SYSFS_FLAG_REMOVED = 0x0010, + SYSFS_FLAG_NS = 0x0020, + SYSFS_FLAG_HAS_SEQ_SHOW = 0x0040, + SYSFS_FLAG_HAS_MMAP = 0x0080, + SYSFS_FLAG_LOCKDEP = 0x0100, +}; + +/* type-specific structures for sysfs_dirent->s_* union members */ +struct sysfs_elem_dir { + unsigned long subdirs; + /* children rbtree starts here and goes through sd->s_rb */ + struct rb_root children; + + /* + * The kernfs hierarchy this directory belongs to. This fits + * better directly in sysfs_dirent but is here to save space. + */ + struct kernfs_root *root; +}; + +struct sysfs_elem_symlink { + struct sysfs_dirent *target_sd; +}; + +struct sysfs_elem_attr { + const struct kernfs_ops *ops; + struct sysfs_open_dirent *open; + loff_t size; +}; + +/* + * sysfs_dirent - the building block of sysfs hierarchy. Each and every + * sysfs node is represented by single sysfs_dirent. Most fields are + * private to kernfs and shouldn't be accessed directly by kernfs users. + * + * As long as s_count reference is held, the sysfs_dirent itself is + * accessible. Dereferencing s_elem or any other outer entity + * requires s_active reference. + */ +struct sysfs_dirent { + atomic_t s_count; + atomic_t s_active; +#ifdef CONFIG_DEBUG_LOCK_ALLOC + struct lockdep_map dep_map; +#endif + /* the following two fields are published */ + struct sysfs_dirent *s_parent; + const char *s_name; + + struct rb_node s_rb; + + union { + struct completion *completion; + struct sysfs_dirent *removed_list; + } u; + + const void *s_ns; /* namespace tag */ + unsigned int s_hash; /* ns + name hash */ + union { + struct sysfs_elem_dir s_dir; + struct sysfs_elem_symlink s_symlink; + struct sysfs_elem_attr s_attr; + }; + + void *priv; + + unsigned short s_flags; + umode_t s_mode; + unsigned int s_ino; + struct sysfs_inode_attrs *s_iattr; +}; struct kernfs_root { /* published fields */ @@ -82,6 +170,26 @@ struct kernfs_ops { #ifdef CONFIG_SYSFS +static inline enum kernfs_node_type sysfs_type(struct sysfs_dirent *sd) +{ + return sd->s_flags & SYSFS_TYPE_MASK; +} + +/** + * kernfs_enable_ns - enable namespace under a directory + * @sd: directory of interest, should be empty + * + * This is to be called right after @sd is created to enable namespace + * under it. All children of @sd must have non-NULL namespace tags and + * only the ones which match the super_block's tag will be visible. + */ +static inline void kernfs_enable_ns(struct sysfs_dirent *sd) +{ + WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR); + WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children)); + sd->s_flags |= SYSFS_FLAG_NS; +} + struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent, const char *name, const void *ns); void kernfs_get(struct sysfs_dirent *sd); @@ -107,7 +215,6 @@ int kernfs_remove_by_name_ns(struct sysfs_dirent *parent, const char *name, const void *ns); int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent, const char *new_name, const void *new_ns); -void kernfs_enable_ns(struct sysfs_dirent *sd); int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr); void kernfs_notify(struct sysfs_dirent *sd); @@ -120,6 +227,11 @@ void kernfs_init(void); #else /* CONFIG_SYSFS */ +static inline enum kernfs_node_type sysfs_type(struct sysfs_dirent *sd) +{ return 0; } /* whatever */ + +static inline void kernfs_enable_ns(struct sysfs_dirent *sd) { } + static inline struct sysfs_dirent * kernfs_find_and_get_ns(struct sysfs_dirent *parent, const char *name, const void *ns) @@ -161,8 +273,6 @@ static inline int kernfs_rename_ns(struct sysfs_dirent *sd, const char *new_name, const void *new_ns) { return -ENOSYS; } -static inline void kernfs_enable_ns(struct sysfs_dirent *sd) { } - static inline int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr) { return -ENOSYS; } |