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Commit 7e7f7749 authored by Ross Zwisler's avatar Ross Zwisler Committed by Linus Torvalds
Browse files

mm: add find_get_entries_tag() 



Add find_get_entries_tag() to the family of functions that include
find_get_entries(), find_get_pages() and find_get_pages_tag().  This is
needed for DAX dirty page handling because we need a list of both page
offsets and radix tree entries ('indices' and 'entries' in this
function) that are marked with the PAGECACHE_TAG_TOWRITE tag.

Signed-off-by: default avatarRoss Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jeff Layton <jlayton@poochiereds.net>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f9fe48be

include/linux/pagemap.h

+3 −0
Original line number Diff line number Diff line
@@ -361,6 +361,9 @@ unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start, 
			       unsigned int nr_pages, struct page **pages);

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

			int tag, unsigned int nr_pages, struct page **pages);

unsigned find_get_entries_tag(struct address_space *mapping, pgoff_t start,

			int tag, unsigned int nr_entries,

			struct page **entries, pgoff_t *indices);



struct page *grab_cache_page_write_begin(struct address_space *mapping,

			pgoff_t index, unsigned flags);

mm/filemap.c

+68 −0
Original line number Diff line number Diff line
@@ -1499,6 +1499,74 @@ unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, 
}

EXPORT_SYMBOL(find_get_pages_tag);



/**

 * find_get_entries_tag - find and return entries that match @tag

 * @mapping:	the address_space to search

 * @start:	the starting page cache index

 * @tag:	the tag index

 * @nr_entries:	the maximum number of entries

 * @entries:	where the resulting entries are placed

 * @indices:	the cache indices corresponding to the entries in @entries

 *

 * Like find_get_entries, except we only return entries which are tagged with

 * @tag.

 */

unsigned find_get_entries_tag(struct address_space *mapping, pgoff_t start,

			int tag, unsigned int nr_entries,

			struct page **entries, pgoff_t *indices)

{

	void **slot;

	unsigned int ret = 0;

	struct radix_tree_iter iter;



	if (!nr_entries)

		return 0;



	rcu_read_lock();

restart:

	radix_tree_for_each_tagged(slot, &mapping->page_tree,

				   &iter, start, tag) {

		struct page *page;

repeat:

		page = radix_tree_deref_slot(slot);

		if (unlikely(!page))

			continue;

		if (radix_tree_exception(page)) {

			if (radix_tree_deref_retry(page)) {

				/*

				 * Transient condition which can only trigger

				 * when entry at index 0 moves out of or back

				 * to root: none yet gotten, safe to restart.

				 */

				goto restart;

			}



			/*

			 * A shadow entry of a recently evicted page, a swap

			 * entry from shmem/tmpfs or a DAX entry.  Return it

			 * without attempting to raise page count.

			 */

			goto export;

		}

		if (!page_cache_get_speculative(page))

			goto repeat;



		/* Has the page moved? */

		if (unlikely(page != *slot)) {

			page_cache_release(page);

			goto repeat;

		}

export:

		indices[ret] = iter.index;

		entries[ret] = page;

		if (++ret == nr_entries)

			break;

	}

	rcu_read_unlock();

	return ret;

}

EXPORT_SYMBOL(find_get_entries_tag);



/*

 * CD/DVDs are error prone. When a medium error occurs, the driver may fail

 * a _large_ part of the i/o request. Imagine the worst scenario: