linux-kernel - [PATCH 1/5] mtd: fix bdev exclusive open bugs in block2mtd::add

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Date:	Mon,  1 Nov 2010 17:15:25 +0100
From:	Tejun Heo <tj@...nel.org>
To:	axboe@...nel.dk, hch@...radead.org, linux-kernel@...r.kernel.org,
	petero2@...ia.com, schwidefsky@...ibm.com,
	heiko.carstens@...ibm.com, jack@...e.cz, akpm@...ux-foundation.org,
	adilger.kernel@...ger.ca, tytso@....edu, mfasheh@...e.com,
	joel.becker@...cle.com, aelder@....com, dm-devel@...hat.com,
	drbd-dev@...ts.linbit.com, neilb@...e.de, leochen@...adcom.com,
	sbranden@...adcom.com, chris.mason@...cle.com, swhiteho@...hat.com,
	shaggy@...ux.vnet.ibm.com, joern@...fs.org,
	konishi.ryusuke@....ntt.co.jp, reiserfs-devel@...r.kernel.org,
	viro@...iv.linux.org.uk
Cc:	Tejun Heo <tj@...nel.org>, linux-mtd@...ts.infradead.org
Subject: [PATCH 1/5] mtd: fix bdev exclusive open bugs in block2mtd::add_device()

There are two bdev exclusive open bugs.

* open_bdev_exclusive() must not be called with NULL holder.  Use dev
  as the holder.

* open_by_devnum() doesn't open the bdev exclusively but
  block2mtd_free_device() always assumes it.  Explicitly claim the
  bdev.

The latter is rather clumsy but will be simplified with future
blkdev_get/put() cleanups.

Signed-off-by: Tejun Heo <tj@...nel.org>
Cc: linux-mtd@...ts.infradead.org
---
 drivers/mtd/devices/block2mtd.c |   11 ++++++++++-
 1 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/drivers/mtd/devices/block2mtd.c b/drivers/mtd/devices/block2mtd.c
index 2cf0cc6..806a9ed 100644
--- a/drivers/mtd/devices/block2mtd.c
+++ b/drivers/mtd/devices/block2mtd.c
@@ -246,7 +246,7 @@ static struct block2mtd_dev *add_device(char *devname, int erase_size)
 		return NULL;
 
 	/* Get a handle on the device */
-	bdev = open_bdev_exclusive(devname, FMODE_READ|FMODE_WRITE, NULL);
+	bdev = open_bdev_exclusive(devname, FMODE_READ|FMODE_WRITE, dev);
 #ifndef MODULE
 	if (IS_ERR(bdev)) {
 
@@ -256,6 +256,15 @@ static struct block2mtd_dev *add_device(char *devname, int erase_size)
 		dev_t devt = name_to_dev_t(devname);
 		if (devt) {
 			bdev = open_by_devnum(devt, FMODE_WRITE | FMODE_READ);
+			if (!IS_ERR(bdev)) {
+				int ret;
+				ret = bd_claim(bdev, dev);
+				if (ret) {
+					blkdev_put(bdev,
+						   FMODE_READ | FMODE_WRITE);
+					bdev = ERR_PTR(ret);
+				}
+			}
 		}
 	}
 #endif
-- 
1.7.1

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