linux-kernel - [PATCH 3.14 38/44] dont remove from shrink list in select

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Date:	Fri, 14 Aug 2015 10:45:15 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>,
	"Nicholas A. Bellinger" <nab@...ux-iscsi.org>
Subject: [PATCH 3.14 38/44] dont remove from shrink list in select_collect()

3.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Al Viro <viro@...iv.linux.org.uk>

commit fe91522a7ba82ca1a51b07e19954b3825e4aaa22 upstream.

	If we find something already on a shrink list, just increment
data->found and do nothing else.  Loops in shrink_dcache_parent() and
check_submounts_and_drop() will do the right thing - everything we
did put into our list will be evicted and if there had been nothing,
but data->found got non-zero, well, we have somebody else shrinking
those guys; just try again.

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
Cc: "Nicholas A. Bellinger" <nab@...ux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/dcache.c |   31 ++++++++++---------------------
 1 file changed, 10 insertions(+), 21 deletions(-)

--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1231,34 +1231,23 @@ static enum d_walk_ret select_collect(vo
 	if (data->start == dentry)
 		goto out;
 
-	/*
-	 * move only zero ref count dentries to the dispose list.
-	 *
-	 * Those which are presently on the shrink list, being processed
-	 * by shrink_dentry_list(), shouldn't be moved.  Otherwise the
-	 * loop in shrink_dcache_parent() might not make any progress
-	 * and loop forever.
-	 */
-	if (dentry->d_lockref.count) {
-		dentry_lru_del(dentry);
-	} else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) {
-		/*
-		 * We can't use d_lru_shrink_move() because we
-		 * need to get the global LRU lock and do the
-		 * LRU accounting.
-		 */
-		d_lru_del(dentry);
-		d_shrink_add(dentry, &data->dispose);
+	if (dentry->d_flags & DCACHE_SHRINK_LIST) {
 		data->found++;
-		ret = D_WALK_NORETRY;
+	} else {
+		if (dentry->d_flags & DCACHE_LRU_LIST)
+			d_lru_del(dentry);
+		if (!dentry->d_lockref.count) {
+			d_shrink_add(dentry, &data->dispose);
+			data->found++;
+		}
 	}
 	/*
 	 * We can return to the caller if we have found some (this
 	 * ensures forward progress). We'll be coming back to find
 	 * the rest.
 	 */
-	if (data->found && need_resched())
-		ret = D_WALK_QUIT;
+	if (!list_empty(&data->dispose))
+		ret = need_resched() ? D_WALK_QUIT : D_WALK_NORETRY;
 out:
 	return ret;
 }


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