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authorTejun Heo <tj@kernel.org>2015-08-18 14:54:55 -0700
committerJens Axboe <axboe@fb.com>2015-08-18 15:49:15 -0700
commit9acee9c551f045d2c5b5261aa587331423fd7d92 (patch)
tree16f0ecafd4f842d6352dd85913283a262a8e56f0
parent60292bcc1b240a6708aa531c8ece1da2a78d560a (diff)
kernfs: implement kernfs_path_len()
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>
-rw-r--r--fs/kernfs/dir.c23
-rw-r--r--include/linux/kernfs.h4
2 files changed, 27 insertions, 0 deletions
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 2d48d28e1640..91e004518237 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -92,6 +92,29 @@ int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen)
}
/**
+ * 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
* @buf: buffer to copy @kn's name into
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 123be25ea15a..5d4e9c4b821d 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -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; }