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kernfs: make kernfs_walk_ns() use kernfs_pr_cont_buf[]

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kernfs_walk_ns() uses a static path_buf[PATH_MAX] to separate out path
components.  Keeping around the 4k buffer just for kernfs_walk_ns() is
wasteful.  This patch makes it piggyback on kernfs_pr_cont_buf[]
instead.  This requires kernfs_walk_ns() to hold kernfs_rename_lock.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tejun Heo 2016-01-15 12:30:14 -05:00 committed by Greg Kroah-Hartman
parent 388f7b1d6e
commit e56ed358af
1 changed files with 14 additions and 5 deletions
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19
fs/kernfs/dir.c
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@ -691,15 +691,22 @@ static struct kernfs_node *kernfs_walk_ns(struct kernfs_node *parent,
const unsigned char *path,
const void *ns)
{
static char path_buf[PATH_MAX]; /* protected by kernfs_mutex */
size_t len = strlcpy(path_buf, path, PATH_MAX);
char *p = path_buf;
char *name;
size_t len;
char *p, *name;
lockdep_assert_held(&kernfs_mutex);
if (len >= PATH_MAX)
/* grab kernfs_rename_lock to piggy back on kernfs_pr_cont_buf */
spin_lock_irq(&kernfs_rename_lock);
len = strlcpy(kernfs_pr_cont_buf, path, sizeof(kernfs_pr_cont_buf));
if (len >= sizeof(kernfs_pr_cont_buf)) {
spin_unlock_irq(&kernfs_rename_lock);
return NULL;
}
p = kernfs_pr_cont_buf;
while ((name = strsep(&p, "/")) && parent) {
if (*name == '\0')
@ -707,6 +714,8 @@ static struct kernfs_node *kernfs_walk_ns(struct kernfs_node *parent,
parent = kernfs_find_ns(parent, name, ns);
}
spin_unlock_irq(&kernfs_rename_lock);
return parent;
}