diff options
| author | NeilBrown <neilb@suse.de> | 2014-08-08 14:19:54 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-08-08 15:57:19 -0700 |
| commit | 668128e90b9596668141539326178dacc42af188 (patch) | |
| tree | d68268b71a156f2ed76999384e46d3dc36236975 /fs/autofs4 | |
| parent | c312442fe3ce9561137910db35ad1409d67dbac6 (diff) | |
| download | lwn-668128e90b9596668141539326178dacc42af188.tar.gz lwn-668128e90b9596668141539326178dacc42af188.zip | |
autofs4: don't take spinlock when not needed in autofs4_lookup_expiring
If the expiring_list is empty, we can avoid a costly spinlock in the
rcu-walk path through autofs4_d_manage (once the rest of the path
becomes rcu-walk friendly).
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/autofs4')
| -rw-r--r-- | fs/autofs4/root.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c index cc87c1abac97..fb202cadd4b3 100644 --- a/fs/autofs4/root.c +++ b/fs/autofs4/root.c @@ -166,8 +166,10 @@ static struct dentry *autofs4_lookup_active(struct dentry *dentry) const unsigned char *str = name->name; struct list_head *p, *head; - spin_lock(&sbi->lookup_lock); head = &sbi->active_list; + if (list_empty(head)) + return NULL; + spin_lock(&sbi->lookup_lock); list_for_each(p, head) { struct autofs_info *ino; struct dentry *active; @@ -218,8 +220,10 @@ static struct dentry *autofs4_lookup_expiring(struct dentry *dentry) const unsigned char *str = name->name; struct list_head *p, *head; - spin_lock(&sbi->lookup_lock); head = &sbi->expiring_list; + if (list_empty(head)) + return NULL; + spin_lock(&sbi->lookup_lock); list_for_each(p, head) { struct autofs_info *ino; struct dentry *expiring; |