Commit 137db333 authored by Darrick J. Wong's avatar Darrick J. Wong
Browse files

xfs: teach xfile to pass back direct-map pages to caller 



Certain xfile array operations (such as sorting) can be sped up quite a
bit by allowing xfile users to grab a page to bulk-read the records
contained within it.  Create helper methods to facilitate this.

Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
parent c390c645

fs/xfs/scrub/trace.h

+2 −0
Original line number Diff line number Diff line
@@ -821,6 +821,8 @@ DEFINE_EVENT(xfile_class, name, \ 
DEFINE_XFILE_EVENT(xfile_pread);

DEFINE_XFILE_EVENT(xfile_pwrite);

DEFINE_XFILE_EVENT(xfile_seek_data);

DEFINE_XFILE_EVENT(xfile_get_page);

DEFINE_XFILE_EVENT(xfile_put_page);



TRACE_EVENT(xfarray_create,

	TP_PROTO(struct xfarray *xfa, unsigned long long required_capacity),

fs/xfs/scrub/xfile.c

+108 −0
Original line number Diff line number Diff line
@@ -310,3 +310,111 @@ xfile_stat( 
	statbuf->bytes = ks.blocks << SECTOR_SHIFT;

	return 0;

}



/*

 * Grab the (locked) page for a memory object.  The object cannot span a page

 * boundary.  Returns 0 (and a locked page) if successful, -ENOTBLK if we

 * cannot grab the page, or the usual negative errno.

 */

int

xfile_get_page(

	struct xfile		*xf,

	loff_t			pos,

	unsigned int		len,

	struct xfile_page	*xfpage)

{

	struct inode		*inode = file_inode(xf->file);

	struct address_space	*mapping = inode->i_mapping;

	const struct address_space_operations *aops = mapping->a_ops;

	struct page		*page = NULL;

	void			*fsdata = NULL;

	loff_t			key = round_down(pos, PAGE_SIZE);

	unsigned int		pflags;

	int			error;



	if (inode->i_sb->s_maxbytes - pos < len)

		return -ENOMEM;

	if (len > PAGE_SIZE - offset_in_page(pos))

		return -ENOTBLK;



	trace_xfile_get_page(xf, pos, len);



	pflags = memalloc_nofs_save();



	/*

	 * We call write_begin directly here to avoid all the freezer

	 * protection lock-taking that happens in the normal path.  shmem

	 * doesn't support fs freeze, but lockdep doesn't know that and will

	 * trip over that.

	 */

	error = aops->write_begin(NULL, mapping, key, PAGE_SIZE, &page,

			&fsdata);

	if (error)

		goto out_pflags;



	/* We got the page, so make sure we push out EOF. */

	if (i_size_read(inode) < pos + len)

		i_size_write(inode, pos + len);



	/*

	 * If the page isn't up to date, fill it with zeroes before we hand it

	 * to the caller and make sure the backing store will hold on to them.

	 */

	if (!PageUptodate(page)) {

		void	*kaddr;



		kaddr = kmap_local_page(page);

		memset(kaddr, 0, PAGE_SIZE);

		kunmap_local(kaddr);

		SetPageUptodate(page);

	}



	/*

	 * Mark each page dirty so that the contents are written to some

	 * backing store when we drop this buffer, and take an extra reference

	 * to prevent the xfile page from being swapped or removed from the

	 * page cache by reclaim if the caller unlocks the page.

	 */

	set_page_dirty(page);

	get_page(page);



	xfpage->page = page;

	xfpage->fsdata = fsdata;

	xfpage->pos = key;

out_pflags:

	memalloc_nofs_restore(pflags);

	return error;

}



/*

 * Release the (locked) page for a memory object.  Returns 0 or a negative

 * errno.

 */

int

xfile_put_page(

	struct xfile		*xf,

	struct xfile_page	*xfpage)

{

	struct inode		*inode = file_inode(xf->file);

	struct address_space	*mapping = inode->i_mapping;

	const struct address_space_operations *aops = mapping->a_ops;

	unsigned int		pflags;

	int			ret;



	trace_xfile_put_page(xf, xfpage->pos, PAGE_SIZE);



	/* Give back the reference that we took in xfile_get_page. */

	put_page(xfpage->page);



	pflags = memalloc_nofs_save();

	ret = aops->write_end(NULL, mapping, xfpage->pos, PAGE_SIZE, PAGE_SIZE,

			xfpage->page, xfpage->fsdata);

	memalloc_nofs_restore(pflags);

	memset(xfpage, 0, sizeof(struct xfile_page));



	if (ret < 0)

		return ret;

	if (ret != PAGE_SIZE)

		return -EIO;

	return 0;

}

fs/xfs/scrub/xfile.h

+10 −0
Original line number Diff line number Diff line
@@ -6,6 +6,12 @@ 
#ifndef __XFS_SCRUB_XFILE_H__

#define __XFS_SCRUB_XFILE_H__



struct xfile_page {

	struct page		*page;

	void			*fsdata;

	loff_t			pos;

};



struct xfile {

	struct file		*file;

};
@@ -54,4 +60,8 @@ struct xfile_stat { 


int xfile_stat(struct xfile *xf, struct xfile_stat *statbuf);



int xfile_get_page(struct xfile *xf, loff_t offset, unsigned int len,

		struct xfile_page *xbuf);

int xfile_put_page(struct xfile *xf, struct xfile_page *xbuf);



#endif /* __XFS_SCRUB_XFILE_H__ */