linux-kernel - [PATCH 03/17] blktrans: track open and close calls.

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Message-Id: <1264863768-27606-4-git-send-email-maximlevitsky@gmail.com>
Date:	Sat, 30 Jan 2010 17:02:34 +0200
From:	Maxim Levitsky <maximlevitsky@...il.com>
To:	David Woodhouse <dwmw2@...radead.org>
Cc:	Artem Bityutskiy <dedekind1@...il.com>,
	linux-mtd <linux-mtd@...ts.infradead.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Alex Dubov <oakad@...oo.com>, joern <joern@...fs.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Maxim Levitsky <maximlevitsky@...il.com>
Subject: [PATCH 03/17] blktrans: track open and close calls.

This patch adds tracking for open and close calls.
Now trans ->open and ->release are never called twise in a row
->release is also called once before mtd device disappers

Proper locking will be added in follow up patch

Signed-off-by: Maxim Levitsky <maximlevitsky@...il.com>
---
 drivers/mtd/mtd_blkdevs.c    |   18 ++++++++++++++++++
 include/linux/mtd/blktrans.h |    1 +
 2 files changed, 19 insertions(+), 0 deletions(-)

diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index 93c87af..966398b 100644
--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -128,6 +128,9 @@ static int blktrans_open(struct block_device *bdev, fmode_t mode)
 	if (!get_mtd_device(NULL, dev->mtd->index))
 		goto out;
 
+	if (dev->open++)
+		goto out;
+
 	if (!try_module_get(tr->owner))
 		goto out_tr;
 
@@ -153,6 +156,10 @@ static int blktrans_release(struct gendisk *disk, fmode_t mode)
 	struct mtd_blktrans_ops *tr = dev->tr;
 	int ret = 0;
 
+	dev->open--;
+	if (dev->open)
+		return 0;
+
 	if (tr->release)
 		ret = tr->release(dev);
 
@@ -304,6 +311,7 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 	if (new->readonly)
 		set_disk_ro(gd, 1);
 
+	new->open = 0;
 	add_disk(gd);
 
 	return 0;
@@ -333,6 +341,16 @@ int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
 	/* Stop the thread */
 	kthread_stop(old->thread);
 
+	if (old->open) {
+		if (old->tr->release)
+			old->tr->release(old);
+		put_mtd_device(old->mtd);
+	}
+
+	/* From now on, no calls into trans can be made */
+	/* Mtd device will be gone real soon now */
+	old->mtd = NULL;
+ 
 	blk_cleanup_queue(old->rq);
 	return 0;
 }
diff --git a/include/linux/mtd/blktrans.h b/include/linux/mtd/blktrans.h
index a4b3928..507f7b2 100644
--- a/include/linux/mtd/blktrans.h
+++ b/include/linux/mtd/blktrans.h
@@ -24,6 +24,7 @@ struct mtd_blktrans_dev {
 	int devnum;
 	unsigned long size;
 	int readonly;
+	int open;
 	struct gendisk *disk;
 	struct task_struct *thread;
 	struct request_queue *rq;
-- 
1.6.3.3

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