Commit 3f666c56 authored by Vivek Goyal's avatar Vivek Goyal Committed by Dan Williams
Browse files

dax: Pass dax_dev instead of bdev to dax_writeback_mapping_range() 



As of now dax_writeback_mapping_range() takes "struct block_device" as a
parameter and dax_dev is searched from bdev name. This also involves taking
a fresh reference on dax_dev and putting that reference at the end of
function.

We are developing a new filesystem virtio-fs and using dax to access host
page cache directly. But there is no block device. IOW, we want to make
use of dax but want to get rid of this assumption that there is always
a block device associated with dax_dev.

So pass in "struct dax_device" as parameter instead of bdev.

ext2/ext4/xfs are current users and they already have a reference on
dax_device. So there is no need to take reference and drop reference to
dax_device on each call of this function.

Suggested-by: default avatarChristoph Hellwig <hch@infradead.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Link: https://lore.kernel.org/r/20200103183307.GB13350@redhat.com


Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent d1eef1c6

fs/dax.c

+1 −7
Original line number Diff line number Diff line
@@ -937,12 +937,11 @@ static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev, 
 * on persistent storage prior to completion of the operation.

 */

int dax_writeback_mapping_range(struct address_space *mapping,

		struct block_device *bdev, struct writeback_control *wbc)

		struct dax_device *dax_dev, struct writeback_control *wbc)

{

	XA_STATE(xas, &mapping->i_pages, wbc->range_start >> PAGE_SHIFT);

	struct inode *inode = mapping->host;

	pgoff_t end_index = wbc->range_end >> PAGE_SHIFT;

	struct dax_device *dax_dev;

	void *entry;

	int ret = 0;

	unsigned int scanned = 0;
@@ -953,10 +952,6 @@ int dax_writeback_mapping_range(struct address_space *mapping, 
	if (!mapping->nrexceptional || wbc->sync_mode != WB_SYNC_ALL)

		return 0;



	dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);

	if (!dax_dev)

		return -EIO;



	trace_dax_writeback_range(inode, xas.xa_index, end_index);



	tag_pages_for_writeback(mapping, xas.xa_index, end_index);
@@ -977,7 +972,6 @@ int dax_writeback_mapping_range(struct address_space *mapping, 
		xas_lock_irq(&xas);

	}

	xas_unlock_irq(&xas);

	put_dax(dax_dev);

	trace_dax_writeback_range_done(inode, xas.xa_index, end_index);

	return ret;

}

fs/ext2/inode.c

+3 −2
Original line number Diff line number Diff line
@@ -960,8 +960,9 @@ ext2_writepages(struct address_space *mapping, struct writeback_control *wbc) 
static int

ext2_dax_writepages(struct address_space *mapping, struct writeback_control *wbc)

{

	return dax_writeback_mapping_range(mapping,

			mapping->host->i_sb->s_bdev, wbc);

	struct ext2_sb_info *sbi = EXT2_SB(mapping->host->i_sb);



	return dax_writeback_mapping_range(mapping, sbi->s_daxdev, wbc);

}



const struct address_space_operations ext2_aops = {

fs/ext4/inode.c

+1 −1
Original line number Diff line number Diff line
@@ -2866,7 +2866,7 @@ static int ext4_dax_writepages(struct address_space *mapping, 
	percpu_down_read(&sbi->s_journal_flag_rwsem);

	trace_ext4_writepages(inode, wbc);



	ret = dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev, wbc);

	ret = dax_writeback_mapping_range(mapping, sbi->s_daxdev, wbc);

	trace_ext4_writepages_result(inode, wbc, ret,

				     nr_to_write - wbc->nr_to_write);

	percpu_up_read(&sbi->s_journal_flag_rwsem);

fs/xfs/xfs_aops.c

+1 −1
Original line number Diff line number Diff line
@@ -587,7 +587,7 @@ xfs_dax_writepages( 


	xfs_iflags_clear(ip, XFS_ITRUNCATED);

	return dax_writeback_mapping_range(mapping,

			xfs_inode_buftarg(ip)->bt_bdev, wbc);

			xfs_inode_buftarg(ip)->bt_daxdev, wbc);

}



STATIC sector_t

include/linux/dax.h

+2 −2
Original line number Diff line number Diff line
@@ -141,7 +141,7 @@ static inline void fs_put_dax(struct dax_device *dax_dev) 


struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev);

int dax_writeback_mapping_range(struct address_space *mapping,

		struct block_device *bdev, struct writeback_control *wbc);

		struct dax_device *dax_dev, struct writeback_control *wbc);



struct page *dax_layout_busy_page(struct address_space *mapping);

dax_entry_t dax_lock_page(struct page *page);
@@ -180,7 +180,7 @@ static inline struct page *dax_layout_busy_page(struct address_space *mapping) 
}



static inline int dax_writeback_mapping_range(struct address_space *mapping,

		struct block_device *bdev, struct writeback_control *wbc)

		struct dax_device *dax_dev, struct writeback_control *wbc)

{

	return -EOPNOTSUPP;

}

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