[PATCH] kernfs: make kernfs_walk_ns() use kernfs_pr_cont_buf[]
From: Tejun Heo <tj@kernel.org>
Date: 2016-01-15 17:30:19
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cgroups, lkml, netfilter-devel
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> --- Hello, Greg, can you please route this one? Thanks. fs/kernfs/dir.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-)
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c@@ -698,15 +698,22 @@ static struct kernfs_node *kernfs_walk_n 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')
@@ -714,6 +721,8 @@ static struct kernfs_node *kernfs_walk_n parent = kernfs_find_ns(parent, name, ns); } + spin_unlock_irq(&kernfs_rename_lock); + return parent; }