From: Cong Wang <xiyou.wangcong@gmail.com>
To: stable@vger.kernel.org
Cc: viro@zeniv.linux.org.uk, gregkh@linuxfoundation.org,
linux-fsdevel@vger.kernel.org
Subject: [Patch 3.14 stable 02/16] fold try_prune_one_dentry()
Date: Thu, 6 Nov 2014 11:37:06 -0800 [thread overview]
Message-ID: <1415302640-5876-3-git-send-email-xiyou.wangcong@gmail.com> (raw)
In-Reply-To: <1415302640-5876-1-git-send-email-xiyou.wangcong@gmail.com>
From: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
(cherry picked from commit 5c47e6d0ad608987b91affbcf7d1fc12dfbe8fb4)
---
fs/dcache.c | 75 +++++++++++++++++++++----------------------------------------
1 file changed, 25 insertions(+), 50 deletions(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index d289bb9..bea71ca 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -786,47 +786,9 @@ void d_prune_aliases(struct inode *inode)
}
EXPORT_SYMBOL(d_prune_aliases);
-/*
- * Try to throw away a dentry - free the inode, dput the parent.
- * Requires dentry->d_lock is held, and dentry->d_count == 0.
- * Releases dentry->d_lock.
- *
- * This may fail if locks cannot be acquired no problem, just try again.
- */
-static struct dentry * try_prune_one_dentry(struct dentry *dentry)
- __releases(dentry->d_lock)
-{
- struct dentry *parent;
-
- parent = dentry_kill(dentry, 0);
- /*
- * If dentry_kill returns NULL, we have nothing more to do.
- * if it returns the same dentry, trylocks failed. In either
- * case, just loop again.
- *
- * Otherwise, we need to prune ancestors too. This is necessary
- * to prevent quadratic behavior of shrink_dcache_parent(), but
- * is also expected to be beneficial in reducing dentry cache
- * fragmentation.
- */
- if (!parent)
- return NULL;
- if (parent == dentry)
- return dentry;
-
- /* Prune ancestors. */
- dentry = parent;
- while (dentry) {
- if (lockref_put_or_lock(&dentry->d_lockref))
- return NULL;
- dentry = dentry_kill(dentry, 1);
- }
- return NULL;
-}
-
static void shrink_dentry_list(struct list_head *list)
{
- struct dentry *dentry;
+ struct dentry *dentry, *parent;
rcu_read_lock();
for (;;) {
@@ -862,22 +824,35 @@ static void shrink_dentry_list(struct list_head *list)
}
rcu_read_unlock();
+ parent = dentry_kill(dentry, 0);
/*
- * If 'try_to_prune()' returns a dentry, it will
- * be the same one we passed in, and d_lock will
- * have been held the whole time, so it will not
- * have been added to any other lists. We failed
- * to get the inode lock.
- *
- * We just add it back to the shrink list.
+ * If dentry_kill returns NULL, we have nothing more to do.
*/
- dentry = try_prune_one_dentry(dentry);
-
- rcu_read_lock();
- if (dentry) {
+ if (!parent) {
+ rcu_read_lock();
+ continue;
+ }
+ if (unlikely(parent == dentry)) {
+ /*
+ * trylocks have failed and d_lock has been held the
+ * whole time, so it could not have been added to any
+ * other lists. Just add it back to the shrink list.
+ */
+ rcu_read_lock();
d_shrink_add(dentry, list);
spin_unlock(&dentry->d_lock);
+ continue;
}
+ /*
+ * We need to prune ancestors too. This is necessary to prevent
+ * quadratic behavior of shrink_dcache_parent(), but is also
+ * expected to be beneficial in reducing dentry cache
+ * fragmentation.
+ */
+ dentry = parent;
+ while (dentry && !lockref_put_or_lock(&dentry->d_lockref))
+ dentry = dentry_kill(dentry, 1);
+ rcu_read_lock();
}
rcu_read_unlock();
}
--
1.8.3.1
next prev parent reply other threads:[~2014-11-06 19:37 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-06 19:37 [Patch 3.14 stable 00/16] vfs: fix dentry shrink list corruption Cong Wang
2014-11-06 19:37 ` [Patch 3.14 stable 01/16] fold d_kill() and d_free() Cong Wang
2015-05-18 17:44 ` Greg KH
2015-05-21 0:31 ` [PATCH 3.14] " Vinson Lee
2015-05-21 0:31 ` [PATCH] " Vinson Lee
2015-06-29 23:56 ` [PATCH 3.14] " Greg KH
2014-11-06 19:37 ` Cong Wang [this message]
2014-11-06 19:37 ` [Patch 3.14 stable 03/16] new helper: dentry_free() Cong Wang
2014-11-06 19:37 ` [Patch 3.14 stable 04/16] expand the call of dentry_lru_del() in dentry_kill() Cong Wang
2014-11-06 19:37 ` [Patch 3.14 stable 05/16] dentry_kill(): don't try to remove from shrink list Cong Wang
2014-11-06 19:37 ` [Patch 3.14 stable 06/16] don't remove from shrink list in select_collect() Cong Wang
2014-11-06 19:37 ` [Patch 3.14 stable 07/16] more graceful recovery in umount_collect() Cong Wang
2014-11-06 19:37 ` [Patch 3.14 stable 08/16] dcache: don't need rcu in shrink_dentry_list() Cong Wang
2014-11-06 19:37 ` [Patch 3.14 stable 09/16] lift the "already marked killed" case into shrink_dentry_list() Cong Wang
2014-11-06 19:37 ` [Patch 3.14 stable 10/16] split dentry_kill() Cong Wang
2014-11-06 19:37 ` [Patch 3.14 stable 11/16] expand dentry_kill(dentry, 0) in shrink_dentry_list() Cong Wang
2014-11-06 19:37 ` [Patch 3.14 stable 12/16] shrink_dentry_list(): take parent's ->d_lock earlier Cong Wang
2014-11-06 19:37 ` [Patch 3.14 stable 13/16] dealing with the rest of shrink_dentry_list() livelock Cong Wang
2014-11-06 19:37 ` [Patch 3.14 stable 14/16] dentry_kill() doesn't need the second argument now Cong Wang
2014-11-06 19:37 ` [Patch 3.14 stable 15/16] dcache: add missing lockdep annotation Cong Wang
2014-11-06 19:37 ` [Patch 3.14 stable 16/16] lock_parent: don't step on stale ->d_parent of all-but-freed one Cong Wang
2015-02-03 23:11 ` [Patch 3.14 stable 00/16] vfs: fix dentry shrink list corruption Greg KH
2015-02-04 3:30 ` Cong Wang
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