Commit 7d828a06 authored by David Howells's avatar David Howells
Browse files

netfs: Provide tools to create a buffer in an xarray 



Provide tools to create a buffer in an xarray, with a function to add new
folios with a mark.  This will be used to create bounce buffer and can be
used more easily to create a list of folios the span of which would require
more than a page's worth of bio_vec structs.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
parent 21d706d5

fs/netfs/internal.h

+13 −0
Original line number Diff line number Diff line
@@ -56,6 +56,19 @@ static inline void netfs_proc_add_rreq(struct netfs_io_request *rreq) {} 
static inline void netfs_proc_del_rreq(struct netfs_io_request *rreq) {}

#endif



/*

 * misc.c

 */

#define NETFS_FLAG_PUT_MARK		BIT(0)

#define NETFS_FLAG_PAGECACHE_MARK	BIT(1)

int netfs_xa_store_and_mark(struct xarray *xa, unsigned long index,

			    struct folio *folio, unsigned int flags,

			    gfp_t gfp_mask);

int netfs_add_folios_to_buffer(struct xarray *buffer,

			       struct address_space *mapping,

			       pgoff_t index, pgoff_t to, gfp_t gfp_mask);

void netfs_clear_buffer(struct xarray *buffer);



/*

 * objects.c

 */

fs/netfs/misc.c

+81 −0
Original line number Diff line number Diff line
@@ -8,6 +8,87 @@ 
#include <linux/swap.h>

#include "internal.h"



/*

 * Attach a folio to the buffer and maybe set marks on it to say that we need

 * to put the folio later and twiddle the pagecache flags.

 */

int netfs_xa_store_and_mark(struct xarray *xa, unsigned long index,

			    struct folio *folio, unsigned int flags,

			    gfp_t gfp_mask)

{

	XA_STATE_ORDER(xas, xa, index, folio_order(folio));



retry:

	xas_lock(&xas);

	for (;;) {

		xas_store(&xas, folio);

		if (!xas_error(&xas))

			break;

		xas_unlock(&xas);

		if (!xas_nomem(&xas, gfp_mask))

			return xas_error(&xas);

		goto retry;

	}



	if (flags & NETFS_FLAG_PUT_MARK)

		xas_set_mark(&xas, NETFS_BUF_PUT_MARK);

	if (flags & NETFS_FLAG_PAGECACHE_MARK)

		xas_set_mark(&xas, NETFS_BUF_PAGECACHE_MARK);

	xas_unlock(&xas);

	return xas_error(&xas);

}



/*

 * Create the specified range of folios in the buffer attached to the read

 * request.  The folios are marked with NETFS_BUF_PUT_MARK so that we know that

 * these need freeing later.

 */

int netfs_add_folios_to_buffer(struct xarray *buffer,

			       struct address_space *mapping,

			       pgoff_t index, pgoff_t to, gfp_t gfp_mask)

{

	struct folio *folio;

	int ret;



	if (to + 1 == index) /* Page range is inclusive */

		return 0;



	do {

		/* TODO: Figure out what order folio can be allocated here */

		folio = filemap_alloc_folio(readahead_gfp_mask(mapping), 0);

		if (!folio)

			return -ENOMEM;

		folio->index = index;

		ret = netfs_xa_store_and_mark(buffer, index, folio,

					      NETFS_FLAG_PUT_MARK, gfp_mask);

		if (ret < 0) {

			folio_put(folio);

			return ret;

		}



		index += folio_nr_pages(folio);

	} while (index <= to && index != 0);



	return 0;

}



/*

 * Clear an xarray buffer, putting a ref on the folios that have

 * NETFS_BUF_PUT_MARK set.

 */

void netfs_clear_buffer(struct xarray *buffer)

{

	struct folio *folio;

	XA_STATE(xas, buffer, 0);



	rcu_read_lock();

	xas_for_each_marked(&xas, folio, ULONG_MAX, NETFS_BUF_PUT_MARK) {

		folio_put(folio);

	}

	rcu_read_unlock();

	xa_destroy(buffer);

}



/**

 * netfs_dirty_folio - Mark folio dirty and pin a cache object for writeback

 * @mapping: The mapping the folio belongs to.

include/linux/netfs.h

+4 −0
Original line number Diff line number Diff line
@@ -109,6 +109,10 @@ static inline int wait_on_page_fscache_killable(struct page *page) 
	return folio_wait_private_2_killable(page_folio(page));

}



/* Marks used on xarray-based buffers */

#define NETFS_BUF_PUT_MARK	XA_MARK_0	/* - Page needs putting  */

#define NETFS_BUF_PAGECACHE_MARK XA_MARK_1	/* - Page needs wb/dirty flag wrangling */



enum netfs_io_source {

	NETFS_FILL_WITH_ZEROES,

	NETFS_DOWNLOAD_FROM_SERVER,