[3.13.y.z extended stable] Patch "[jffs2] kill wbuf_queued/wbuf_dwork_lock" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    [jffs2] kill wbuf_queued/wbuf_dwork_lock

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.10.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 383aa9d37f2dc336f80b87f38ccd23dd72fca698 Mon Sep 17 00:00:00 2001
From: Al Viro <viro at ZenIV.linux.org.uk>
Date: Fri, 1 Aug 2014 20:13:40 +0100
Subject: [jffs2] kill wbuf_queued/wbuf_dwork_lock

commit 99358a1ca53e8e6ce09423500191396f0e6584d2 upstream.

schedule_delayed_work() happening when the work is already pending is
a cheap no-op.  Don't bother with ->wbuf_queued logics - it's both
broken (cancelling ->wbuf_dwork leaves it set, as spotted by Jeff Harris)
and pointless.  It's cheaper to let schedule_delayed_work() handle that
case.

Reported-by: Jeff Harris <jefftharris at gmail.com>
Tested-by: Jeff Harris <jefftharris at gmail.com>
Signed-off-by: Al Viro <viro at zeniv.linux.org.uk>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 fs/jffs2/jffs2_fs_sb.h |  2 --
 fs/jffs2/wbuf.c        | 17 ++---------------
 2 files changed, 2 insertions(+), 17 deletions(-)

diff --git a/fs/jffs2/jffs2_fs_sb.h b/fs/jffs2/jffs2_fs_sb.h
index 413ef89..046fee8 100644
--- a/fs/jffs2/jffs2_fs_sb.h
+++ b/fs/jffs2/jffs2_fs_sb.h
@@ -134,8 +134,6 @@ struct jffs2_sb_info {
 	struct rw_semaphore wbuf_sem;	/* Protects the write buffer */

 	struct delayed_work wbuf_dwork; /* write-buffer write-out work */
-	int wbuf_queued;                /* non-zero delayed work is queued */
-	spinlock_t wbuf_dwork_lock;     /* protects wbuf_dwork and and wbuf_queued */

 	unsigned char *oobbuf;
 	int oobavail; /* How many bytes are available for JFFS2 in OOB */
diff --git a/fs/jffs2/wbuf.c b/fs/jffs2/wbuf.c
index a6597d6..09ed551 100644
--- a/fs/jffs2/wbuf.c
+++ b/fs/jffs2/wbuf.c
@@ -1162,10 +1162,6 @@ static void delayed_wbuf_sync(struct work_struct *work)
 	struct jffs2_sb_info *c = work_to_sb(work);
 	struct super_block *sb = OFNI_BS_2SFFJ(c);

-	spin_lock(&c->wbuf_dwork_lock);
-	c->wbuf_queued = 0;
-	spin_unlock(&c->wbuf_dwork_lock);
-
 	if (!(sb->s_flags & MS_RDONLY)) {
 		jffs2_dbg(1, "%s()\n", __func__);
 		jffs2_flush_wbuf_gc(c, 0);
@@ -1180,14 +1176,9 @@ void jffs2_dirty_trigger(struct jffs2_sb_info *c)
 	if (sb->s_flags & MS_RDONLY)
 		return;

-	spin_lock(&c->wbuf_dwork_lock);
-	if (!c->wbuf_queued) {
+	delay = msecs_to_jiffies(dirty_writeback_interval * 10);
+	if (queue_delayed_work(system_long_wq, &c->wbuf_dwork, delay))
 		jffs2_dbg(1, "%s()\n", __func__);
-		delay = msecs_to_jiffies(dirty_writeback_interval * 10);
-		queue_delayed_work(system_long_wq, &c->wbuf_dwork, delay);
-		c->wbuf_queued = 1;
-	}
-	spin_unlock(&c->wbuf_dwork_lock);
 }

 int jffs2_nand_flash_setup(struct jffs2_sb_info *c)
@@ -1211,7 +1202,6 @@ int jffs2_nand_flash_setup(struct jffs2_sb_info *c)

 	/* Initialise write buffer */
 	init_rwsem(&c->wbuf_sem);
-	spin_lock_init(&c->wbuf_dwork_lock);
 	INIT_DELAYED_WORK(&c->wbuf_dwork, delayed_wbuf_sync);
 	c->wbuf_pagesize = c->mtd->writesize;
 	c->wbuf_ofs = 0xFFFFFFFF;
@@ -1251,7 +1241,6 @@ int jffs2_dataflash_setup(struct jffs2_sb_info *c) {

 	/* Initialize write buffer */
 	init_rwsem(&c->wbuf_sem);
-	spin_lock_init(&c->wbuf_dwork_lock);
 	INIT_DELAYED_WORK(&c->wbuf_dwork, delayed_wbuf_sync);
 	c->wbuf_pagesize =  c->mtd->erasesize;

@@ -1311,7 +1300,6 @@ int jffs2_nor_wbuf_flash_setup(struct jffs2_sb_info *c) {

 	/* Initialize write buffer */
 	init_rwsem(&c->wbuf_sem);
-	spin_lock_init(&c->wbuf_dwork_lock);
 	INIT_DELAYED_WORK(&c->wbuf_dwork, delayed_wbuf_sync);

 	c->wbuf_pagesize = c->mtd->writesize;
@@ -1346,7 +1334,6 @@ int jffs2_ubivol_setup(struct jffs2_sb_info *c) {
 		return 0;

 	init_rwsem(&c->wbuf_sem);
-	spin_lock_init(&c->wbuf_dwork_lock);
 	INIT_DELAYED_WORK(&c->wbuf_dwork, delayed_wbuf_sync);

 	c->wbuf_pagesize =  c->mtd->writesize;
--
1.9.1