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Commit 87d8fe1e authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

add releasepage hooks to block devices which can be used by file systems 



Implement blkdev_releasepage() to release the buffer_heads and pages
after we release private data belonging to a mounted filesystem.

Cc: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 0087d9fb

fs/block_dev.c

+15 −0
Original line number Diff line number Diff line
@@ -1220,6 +1220,20 @@ static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg) 
	return blkdev_ioctl(bdev, mode, cmd, arg);

}



/*

 * Try to release a page associated with block device when the system

 * is under memory pressure.

 */

static int blkdev_releasepage(struct page *page, gfp_t wait)

{

	struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super;



	if (super && super->s_op->bdev_try_to_free_page)

		return super->s_op->bdev_try_to_free_page(super, page, wait);



	return try_to_free_buffers(page);

}



static const struct address_space_operations def_blk_aops = {

	.readpage	= blkdev_readpage,

	.writepage	= blkdev_writepage,
@@ -1227,6 +1241,7 @@ static const struct address_space_operations def_blk_aops = { 
	.write_begin	= blkdev_write_begin,

	.write_end	= blkdev_write_end,

	.writepages	= generic_writepages,

	.releasepage	= blkdev_releasepage,

	.direct_IO	= blkdev_direct_IO,

};

fs/super.c

+2 −0
Original line number Diff line number Diff line
@@ -800,6 +800,7 @@ int get_sb_bdev(struct file_system_type *fs_type, 
		}



		s->s_flags |= MS_ACTIVE;

		bdev->bd_super = s;

	}



	return simple_set_mnt(mnt, s);
@@ -819,6 +820,7 @@ void kill_block_super(struct super_block *sb) 
	struct block_device *bdev = sb->s_bdev;

	fmode_t mode = sb->s_mode;



	bdev->bd_super = 0;

	generic_shutdown_super(sb);

	sync_blockdev(bdev);

	close_bdev_exclusive(bdev, mode);

include/linux/fs.h

+2 −0
Original line number Diff line number Diff line
@@ -565,6 +565,7 @@ struct address_space { 
struct block_device {

	dev_t			bd_dev;  /* not a kdev_t - it's a search key */

	struct inode *		bd_inode;	/* will die */

	struct super_block *	bd_super;

	int			bd_openers;

	struct mutex		bd_mutex;	/* open/close mutex */

	struct semaphore	bd_mount_sem;
@@ -1385,6 +1386,7 @@ struct super_operations { 
	ssize_t (*quota_read)(struct super_block *, int, char *, size_t, loff_t);

	ssize_t (*quota_write)(struct super_block *, int, const char *, size_t, loff_t);

#endif

	int (*bdev_try_to_free_page)(struct super_block*, struct page*, gfp_t);

};



/*