Commit 35b47146 authored by Vishal Moola (Oracle)'s avatar Vishal Moola (Oracle) Committed by Andrew Morton
Browse files

filemap: add filemap_get_folios_contig() 

Patch series "Convert to filemap_get_folios_contig()", v3.

This patch series replaces find_get_pages_contig() with
filemap_get_folios_contig().


This patch (of 7):

This function is meant to replace find_get_pages_contig().

Unlike find_get_pages_contig(), filemap_get_folios_contig() no longer
takes in a target number of pages to find - It returns up to 15 contiguous
folios.

To be more consistent with filemap_get_folios(),
filemap_get_folios_contig() now also updates the start index passed in,
and takes an end index.

Link: https://lkml.kernel.org/r/20220824004023.77310-1-vishal.moola@gmail.com
Link: https://lkml.kernel.org/r/20220824004023.77310-2-vishal.moola@gmail.com


Signed-off-by: default avatarVishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: David Sterba <dsterba@suse.com>
Cc: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Sterba <dsterb@suse.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 641608f3

include/linux/pagemap.h

+2 −0
Original line number Diff line number Diff line
@@ -718,6 +718,8 @@ static inline struct page *find_subpage(struct page *head, pgoff_t index) 


unsigned filemap_get_folios(struct address_space *mapping, pgoff_t *start,

		pgoff_t end, struct folio_batch *fbatch);

unsigned filemap_get_folios_contig(struct address_space *mapping,

		pgoff_t *start, pgoff_t end, struct folio_batch *fbatch);

unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,

			       unsigned int nr_pages, struct page **pages);

unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,

mm/filemap.c

+73 −0
Original line number Diff line number Diff line
@@ -2196,6 +2196,79 @@ bool folio_more_pages(struct folio *folio, pgoff_t index, pgoff_t max) 
	return index < folio->index + folio_nr_pages(folio) - 1;

}



/**

 * filemap_get_folios_contig - Get a batch of contiguous folios

 * @mapping:	The address_space to search

 * @start:	The starting page index

 * @end:	The final page index (inclusive)

 * @fbatch:	The batch to fill

 *

 * filemap_get_folios_contig() works exactly like filemap_get_folios(),

 * except the returned folios are guaranteed to be contiguous. This may

 * not return all contiguous folios if the batch gets filled up.

 *

 * Return: The number of folios found.

 * Also update @start to be positioned for traversal of the next folio.

 */



unsigned filemap_get_folios_contig(struct address_space *mapping,

		pgoff_t *start, pgoff_t end, struct folio_batch *fbatch)

{

	XA_STATE(xas, &mapping->i_pages, *start);

	unsigned long nr;

	struct folio *folio;



	rcu_read_lock();



	for (folio = xas_load(&xas); folio && xas.xa_index <= end;

			folio = xas_next(&xas)) {

		if (xas_retry(&xas, folio))

			continue;

		/*

		 * If the entry has been swapped out, we can stop looking.

		 * No current caller is looking for DAX entries.

		 */

		if (xa_is_value(folio))

			goto update_start;



		if (!folio_try_get_rcu(folio))

			goto retry;



		if (unlikely(folio != xas_reload(&xas)))

			goto put_folio;



		if (!folio_batch_add(fbatch, folio)) {

			nr = folio_nr_pages(folio);



			if (folio_test_hugetlb(folio))

				nr = 1;

			*start = folio->index + nr;

			goto out;

		}

		continue;

put_folio:

		folio_put(folio);



retry:

		xas_reset(&xas);

	}



update_start:

	nr = folio_batch_count(fbatch);



	if (nr) {

		folio = fbatch->folios[nr - 1];

		if (folio_test_hugetlb(folio))

			*start = folio->index + 1;

		else

			*start = folio->index + folio_nr_pages(folio);

	}

out:

	rcu_read_unlock();

	return folio_batch_count(fbatch);

}

EXPORT_SYMBOL(filemap_get_folios_contig);



/**

 * find_get_pages_contig - gang contiguous pagecache lookup

 * @mapping:	The address_space to search