The patch titled
Subject: autofs4: don't take spinlock when not needed in autofs4_lookup_expiring
has been added to the -mm tree. Its filename is
autofs4-dont-take-spinlock-when-not-needed-in-autofs4_lookup_expiring.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/autofs4-dont-take-spinlock-when-not-needed-in-autofs4_lookup_expiring.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/autofs4-dont-take-spinlock-when-not-needed-in-autofs4_lookup_expiring.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: NeilBrown <neilb@xxxxxxx>
Subject: 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@xxxxxxx>
Reviewed-by: Ian Kent <raven@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/autofs4/root.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff -puN fs/autofs4/root.c~autofs4-dont-take-spinlock-when-not-needed-in-autofs4_lookup_expiring fs/autofs4/root.c
--- a/fs/autofs4/root.c~autofs4-dont-take-spinlock-when-not-needed-in-autofs4_lookup_expiring
+++ a/fs/autofs4/root.c
@@ -166,8 +166,10 @@ static struct dentry *autofs4_lookup_act
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_exp
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;
_
Patches currently in -mm which might be from neilb@xxxxxxx are
autofs4-remove-unused-autofs4_ispending.patch
autofs4-remove-a-redundant-assignment.patch
autofs4-comment-typo-remove-a-a-doubled-word.patch
autofs4-remove-some-unused-inline-functions.patch
autofs4-dont-take-spinlock-when-not-needed-in-autofs4_lookup_expiring.patch
linux-next.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
