mm: implement find_get_pages_range_tag()

Patch series "Ranged pagevec tagged lookup", v3.

In this series I provide a ranged variant of pagevec_lookup_tag() and
use it in places where it makes sense.  This series removes some common
code and it also has a potential for speeding up some operations
similarly as for pagevec_lookup_range() (but for now I can think of only
artificial cases where this happens).

This patch (of 16):

Implement a variant of find_get_pages_tag() that stops iterating at
given index.  Lots of users of this function (through pagevec_lookup())
actually want a range lookup and all of them are currently open-coding
this.

Also create corresponding pagevec_lookup_range_tag() function.

Link: http://lkml.kernel.org/r/20171009151359.31984-2-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Bob Peterson <rpeterso@redhat.com>
Cc: Chao Yu <yuchao0@huawei.com>
Cc: David Howells <dhowells@redhat.com>
Cc: David Sterba <dsterba@suse.com>
Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Steve French <sfrench@samba.org>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index e08b5339023c0afae64a0ecb7a204ae3b4cb5295..956d6a80e126483b06319cfceeb578ab68db4bca 100644 (file)
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -366,8 +366,16 @@ static inline unsigned find_get_pages(struct address_space *mapping,
 }
 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_pages_range_tag(struct address_space *mapping, pgoff_t *index,
+                       pgoff_t end, int tag, unsigned int nr_pages,
+                       struct page **pages);
+static inline unsigned find_get_pages_tag(struct address_space *mapping,
+                       pgoff_t *index, int tag, unsigned int nr_pages,
+                       struct page **pages)
+{
+       return find_get_pages_range_tag(mapping, index, (pgoff_t)-1, tag,
+                                       nr_pages, 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);

diff --git a/include/linux/pagevec.h b/include/linux/pagevec.h
index 2636c0c0f279333959f2155adc4995d527257f9d..afc718f586f85d7a1f4accc5692bde265351d17f 100644 (file)
--- a/include/linux/pagevec.h
+++ b/include/linux/pagevec.h
@@ -38,9 +38,16 @@ static inline unsigned pagevec_lookup(struct pagevec *pvec,
        return pagevec_lookup_range(pvec, mapping, start, (pgoff_t)-1);
 }
 
-unsigned pagevec_lookup_tag(struct pagevec *pvec,
+unsigned pagevec_lookup_range_tag(struct pagevec *pvec,
+               struct address_space *mapping, pgoff_t *index, pgoff_t end,
+               int tag, unsigned nr_pages);
+static inline unsigned pagevec_lookup_tag(struct pagevec *pvec,
                struct address_space *mapping, pgoff_t *index, int tag,
-               unsigned nr_pages);
+               unsigned nr_pages)
+{
+       return pagevec_lookup_range_tag(pvec, mapping, index, (pgoff_t)-1, tag,
+                                       nr_pages);
+}
 
 static inline void pagevec_init(struct pagevec *pvec, int cold)
 {

diff --git a/mm/filemap.c b/mm/filemap.c
index 594d73fef8b43bae852f4f7ace1e8cfc46b23690..cf74d0dacc6a93b1b7ae7dcdbd8e6070821d0c62 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1754,9 +1754,10 @@ repeat:
 EXPORT_SYMBOL(find_get_pages_contig);
 
 /**
- * find_get_pages_tag - find and return pages that match @tag
+ * find_get_pages_range_tag - find and return pages in given range matching @tag
  * @mapping:   the address_space to search
  * @index:     the starting page index
+ * @end:       The final page index (inclusive)
  * @tag:       the tag index
  * @nr_pages:  the maximum number of pages
  * @pages:     where the resulting pages are placed
@@ -1764,8 +1765,9 @@ EXPORT_SYMBOL(find_get_pages_contig);
  * 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.
  */
-unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
-                       int tag, unsigned int nr_pages, struct page **pages)
+unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,
+                       pgoff_t end, int tag, unsigned int nr_pages,
+                       struct page **pages)
 {
        struct radix_tree_iter iter;
        void **slot;
@@ -1778,6 +1780,9 @@ unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
        radix_tree_for_each_tagged(slot, &mapping->page_tree,
                                   &iter, *index, tag) {
                struct page *head, *page;
+
+               if (iter.index > end)
+                       break;
 repeat:
                page = radix_tree_deref_slot(slot);
                if (unlikely(!page))
@@ -1819,18 +1824,28 @@ repeat:
                }
 
                pages[ret] = page;
-               if (++ret == nr_pages)
-                       break;
+               if (++ret == nr_pages) {
+                       *index = pages[ret - 1]->index + 1;
+                       goto out;
+               }
        }
 
+       /*
+        * We come here when we got at @end. We take care to not overflow the
+        * index @index as it confuses some of the callers. This breaks the
+        * iteration when there is page at index -1 but that is already broken
+        * anyway.
+        */
+       if (end == (pgoff_t)-1)
+               *index = (pgoff_t)-1;
+       else
+               *index = end + 1;
+out:
        rcu_read_unlock();
 
-       if (ret)
-               *index = pages[ret - 1]->index + 1;
-
        return ret;
 }
-EXPORT_SYMBOL(find_get_pages_tag);
+EXPORT_SYMBOL(find_get_pages_range_tag);
 
 /**
  * find_get_entries_tag - find and return entries that match @tag

diff --git a/mm/swap.c b/mm/swap.c
index a77d68f2c1b61de1bc8102656e7e482a442963b1..e1c74eb8a775d4e8985caa070bb0b93efce70843 100644 (file)
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -986,14 +986,15 @@ unsigned pagevec_lookup_range(struct pagevec *pvec,
 }
 EXPORT_SYMBOL(pagevec_lookup_range);
 
-unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
-               pgoff_t *index, int tag, unsigned nr_pages)
+unsigned pagevec_lookup_range_tag(struct pagevec *pvec,
+               struct address_space *mapping, pgoff_t *index, pgoff_t end,
+               int tag, unsigned nr_pages)
 {
-       pvec->nr = find_get_pages_tag(mapping, index, tag,
+       pvec->nr = find_get_pages_range_tag(mapping, index, end, tag,
                                        nr_pages, pvec->pages);
        return pagevec_count(pvec);
 }
-EXPORT_SYMBOL(pagevec_lookup_tag);
+EXPORT_SYMBOL(pagevec_lookup_range_tag);
 
 /*
  * Perform any setup for the swap system