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authorJens Axboe <axboe@suse.de>2006-04-27 08:46:01 +0200
committerJens Axboe <axboe@nelson.home.kernel.dk>2006-04-27 08:59:48 +0200
commitebf43500ef148a380bd132743c3fc530111ac620 (patch)
tree01ddb60f5662cf92b96b0468bf9820518a611209 /mm/filemap.c
parenteb645a24de82496434cc81171d7f350edb327399 (diff)
downloadop-kernel-dev-ebf43500ef148a380bd132743c3fc530111ac620.zip
op-kernel-dev-ebf43500ef148a380bd132743c3fc530111ac620.tar.gz
[PATCH] Add find_get_pages_contig(): contiguous variant of find_get_pages()
find_get_pages_contig() will break out if we hit a hole in the page cache. From Andrew Morton, small modifications and documentation by me. Signed-off-by: Jens Axboe <axboe@suse.de>
Diffstat (limited to 'mm/filemap.c')
-rw-r--r--mm/filemap.c32
1 files changed, 32 insertions, 0 deletions
diff --git a/mm/filemap.c b/mm/filemap.c
index 3ef2073..fd57442 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -697,6 +697,38 @@ unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
return ret;
}
+/**
+ * find_get_pages_contig - gang contiguous pagecache lookup
+ * @mapping: The address_space to search
+ * @index: The starting page index
+ * @nr_pages: The maximum number of pages
+ * @pages: Where the resulting pages are placed
+ *
+ * find_get_pages_contig() works exactly like find_get_pages(), except
+ * that the returned number of pages are guaranteed to be contiguous.
+ *
+ * find_get_pages_contig() returns the number of pages which were found.
+ */
+unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
+ unsigned int nr_pages, struct page **pages)
+{
+ unsigned int i;
+ unsigned int ret;
+
+ read_lock_irq(&mapping->tree_lock);
+ ret = radix_tree_gang_lookup(&mapping->page_tree,
+ (void **)pages, index, nr_pages);
+ for (i = 0; i < ret; i++) {
+ if (pages[i]->mapping == NULL || pages[i]->index != index)
+ break;
+
+ page_cache_get(pages[i]);
+ index++;
+ }
+ read_unlock_irq(&mapping->tree_lock);
+ return i;
+}
+
/*
* Like find_get_pages, except we only return pages which are tagged with
* `tag'. We update *index to index the next page for the traversal.
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