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authorArnd Bergmann <arnd@arndb.de>2010-08-07 18:25:34 +0200
committerJens Axboe <jaxboe@fusionio.com>2010-08-07 18:25:34 +0200
commit6e9624b8caec290d28b4c6d9ec75749df6372b87 (patch)
tree47225b544e1da82742795553dc4e8aa70c17afdc /drivers/md
parent8a6cfeb6deca3a8fefd639d898b0d163c0b5d368 (diff)
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block: push down BKL into .open and .release
The open and release block_device_operations are currently called with the BKL held. In order to change that, we must first make sure that all drivers that currently rely on this have no regressions. This blindly pushes the BKL into all .open and .release operations for all block drivers to prepare for the next step. The drivers can subsequently replace the BKL with their own locks or remove it completely when it can be shown that it is not needed. The functions blkdev_get and blkdev_put are the only remaining users of the big kernel lock in the block layer, besides a few uses in the ioctl code, none of which need to serialize with blkdev_{get,put}. Most of these two functions is also under the protection of bdev->bd_mutex, including the actual calls to ->open and ->release, and the common code does not access any global data structures that need the BKL. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Christoph Hellwig <hch@infradead.org> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/dm.c7
-rw-r--r--drivers/md/md.c6
2 files changed, 13 insertions, 0 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index d505a96845c1..a3f21dc02bd8 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -15,6 +15,7 @@
#include <linux/blkpg.h>
#include <linux/bio.h>
#include <linux/buffer_head.h>
+#include <linux/smp_lock.h>
#include <linux/mempool.h>
#include <linux/slab.h>
#include <linux/idr.h>
@@ -338,6 +339,7 @@ static int dm_blk_open(struct block_device *bdev, fmode_t mode)
{
struct mapped_device *md;
+ lock_kernel();
spin_lock(&_minor_lock);
md = bdev->bd_disk->private_data;
@@ -355,6 +357,7 @@ static int dm_blk_open(struct block_device *bdev, fmode_t mode)
out:
spin_unlock(&_minor_lock);
+ unlock_kernel();
return md ? 0 : -ENXIO;
}
@@ -362,8 +365,12 @@ out:
static int dm_blk_close(struct gendisk *disk, fmode_t mode)
{
struct mapped_device *md = disk->private_data;
+
+ lock_kernel();
atomic_dec(&md->open_count);
dm_put(md);
+ unlock_kernel();
+
return 0;
}
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 1893af678779..700c96edf9b2 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -36,6 +36,7 @@
#include <linux/blkdev.h>
#include <linux/sysctl.h>
#include <linux/seq_file.h>
+#include <linux/smp_lock.h>
#include <linux/buffer_head.h> /* for invalidate_bdev */
#include <linux/poll.h>
#include <linux/ctype.h>
@@ -5902,6 +5903,7 @@ static int md_open(struct block_device *bdev, fmode_t mode)
mddev_t *mddev = mddev_find(bdev->bd_dev);
int err;
+ lock_kernel();
if (mddev->gendisk != bdev->bd_disk) {
/* we are racing with mddev_put which is discarding this
* bd_disk.
@@ -5910,6 +5912,7 @@ static int md_open(struct block_device *bdev, fmode_t mode)
/* Wait until bdev->bd_disk is definitely gone */
flush_scheduled_work();
/* Then retry the open from the top */
+ unlock_kernel();
return -ERESTARTSYS;
}
BUG_ON(mddev != bdev->bd_disk->private_data);
@@ -5923,6 +5926,7 @@ static int md_open(struct block_device *bdev, fmode_t mode)
check_disk_size_change(mddev->gendisk, bdev);
out:
+ unlock_kernel();
return err;
}
@@ -5931,8 +5935,10 @@ static int md_release(struct gendisk *disk, fmode_t mode)
mddev_t *mddev = disk->private_data;
BUG_ON(!mddev);
+ lock_kernel();
atomic_dec(&mddev->openers);
mddev_put(mddev);
+ unlock_kernel();
return 0;
}