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kernfs: implement kernfs_path_len()

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Add a function to determine the path length of a kernfs node.  This
for now will be used by writeback tracepoint updates.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Tejun Heo 2015-08-18 14:54:55 -07:00 committed by Jens Axboe
parent 60292bcc1b
commit 9acee9c551
2 changed files with 27 additions and 0 deletions
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23
fs/kernfs/dir.c
View file

@ -91,6 +91,29 @@ int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen)
return ret;
}
/**
* kernfs_path_len - determine the length of the full path of a given node
* @kn: kernfs_node of interest
*
* The returned length doesn't include the space for the terminating '\0'.
*/
size_t kernfs_path_len(struct kernfs_node *kn)
{
size_t len = 0;
unsigned long flags;
spin_lock_irqsave(&kernfs_rename_lock, flags);
do {
len += strlen(kn->name) + 1;
kn = kn->parent;
} while (kn && kn->parent);
spin_unlock_irqrestore(&kernfs_rename_lock, flags);
return len;
}
/**
* kernfs_path - build full path of a given node
* @kn: kernfs_node of interest

4
include/linux/kernfs.h
View file

@ -266,6 +266,7 @@ static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
}
int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen);
size_t kernfs_path_len(struct kernfs_node *kn);
char * __must_check kernfs_path(struct kernfs_node *kn, char *buf,
size_t buflen);
void pr_cont_kernfs_name(struct kernfs_node *kn);
@ -332,6 +333,9 @@ static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
static inline int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen)
{ return -ENOSYS; }
static inline size_t kernfs_path_len(struct kernfs_node *kn)
{ return 0; }
static inline char * __must_check kernfs_path(struct kernfs_node *kn, char *buf,
size_t buflen)
{ return NULL; }