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Commit dddac6a7 authored by Alan Jenkins's avatar Alan Jenkins Committed by Rafael J. Wysocki
Browse files

PM / Hibernate: Replace bdget call with simple atomic_inc of i_count 

Create bdgrab().  This function copies an existing reference to a
block_device.  It is safe to call from any context.

Hibernation code wishes to copy a reference to the active swap device.
Right now it calls bdget() under a spinlock, but this is wrong because
bdget() can sleep.  It doesn't need a full bdget() because we already
hold a reference to active swap devices (and the spinlock protects
against swapoff).

Fixes http://bugzilla.kernel.org/show_bug.cgi?id=13827



Signed-off-by: default avatarAlan Jenkins <alan-jenkins@tuffmail.co.uk>
Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
parent ec79be26

fs/block_dev.c

+10 −0
Original line number Diff line number Diff line
@@ -564,6 +564,16 @@ struct block_device *bdget(dev_t dev) 


EXPORT_SYMBOL(bdget);



/**

 * bdgrab -- Grab a reference to an already referenced block device

 * @bdev:	Block device to grab a reference to.

 */

struct block_device *bdgrab(struct block_device *bdev)

{

	atomic_inc(&bdev->bd_inode->i_count);

	return bdev;

}



long nr_blockdev_pages(void)

{

	struct block_device *bdev;

include/linux/fs.h

+1 −0
Original line number Diff line number Diff line
@@ -1946,6 +1946,7 @@ extern void putname(const char *name); 
extern int register_blkdev(unsigned int, const char *);

extern void unregister_blkdev(unsigned int, const char *);

extern struct block_device *bdget(dev_t);

extern struct block_device *bdgrab(struct block_device *bdev);

extern void bd_set_size(struct block_device *, loff_t size);

extern void bd_forget(struct inode *inode);

extern void bdput(struct block_device *);

mm/swapfile.c

+2 −2
Original line number Diff line number Diff line
@@ -753,7 +753,7 @@ int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p) 


		if (!bdev) {

			if (bdev_p)

				*bdev_p = bdget(sis->bdev->bd_dev);

				*bdev_p = bdgrab(sis->bdev);



			spin_unlock(&swap_lock);

			return i;
@@ -765,7 +765,7 @@ int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p) 
					struct swap_extent, list);

			if (se->start_block == offset) {

				if (bdev_p)

					*bdev_p = bdget(sis->bdev->bd_dev);

					*bdev_p = bdgrab(sis->bdev);



				spin_unlock(&swap_lock);

				bdput(bdev);