mm + fs: prepare for non-page entries in page cache radix trees
shmem mappings already contain exceptional entries where swap slot
information is remembered.
To be able to store eviction information for regular page cache, prepare
every site dealing with the radix trees directly to handle entries other
than pages.
The common lookup functions will filter out non-page entries and return
NULL for page cache holes, just as before. But provide a raw version of
the API which returns non-page entries as well, and switch shmem over to
use it.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Bob Liu <bob.liu@oracle.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Luigi Semenzato <semenzato@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Metin Doslu <metin@citusdata.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Ozgun Erdogan <ozgun@citusdata.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Roman Gushchin <klamm@yandex-team.ru>
Cc: Ryan Mallon <rmallon@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/shmem.c b/mm/shmem.c
index e470997..a3ba988 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -329,56 +329,6 @@
}
/*
- * Like find_get_pages, but collecting swap entries as well as pages.
- */
-static unsigned shmem_find_get_pages_and_swap(struct address_space *mapping,
- pgoff_t start, unsigned int nr_pages,
- struct page **pages, pgoff_t *indices)
-{
- void **slot;
- unsigned int ret = 0;
- struct radix_tree_iter iter;
-
- if (!nr_pages)
- return 0;
-
- rcu_read_lock();
-restart:
- radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
- 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))
- goto restart;
- /*
- * Otherwise, we must be storing a swap entry
- * here as an exceptional entry: so 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;
- pages[ret] = page;
- if (++ret == nr_pages)
- break;
- }
- rcu_read_unlock();
- return ret;
-}
-
-/*
* Remove swap entry from radix tree, free the swap and its page cache.
*/
static int shmem_free_swap(struct address_space *mapping,
@@ -396,21 +346,6 @@
}
/*
- * Pagevec may contain swap entries, so shuffle up pages before releasing.
- */
-static void shmem_deswap_pagevec(struct pagevec *pvec)
-{
- int i, j;
-
- for (i = 0, j = 0; i < pagevec_count(pvec); i++) {
- struct page *page = pvec->pages[i];
- if (!radix_tree_exceptional_entry(page))
- pvec->pages[j++] = page;
- }
- pvec->nr = j;
-}
-
-/*
* SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
*/
void shmem_unlock_mapping(struct address_space *mapping)
@@ -428,12 +363,12 @@
* Avoid pagevec_lookup(): find_get_pages() returns 0 as if it
* has finished, if it hits a row of PAGEVEC_SIZE swap entries.
*/
- pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
- PAGEVEC_SIZE, pvec.pages, indices);
+ pvec.nr = find_get_entries(mapping, index,
+ PAGEVEC_SIZE, pvec.pages, indices);
if (!pvec.nr)
break;
index = indices[pvec.nr - 1] + 1;
- shmem_deswap_pagevec(&pvec);
+ pagevec_remove_exceptionals(&pvec);
check_move_unevictable_pages(pvec.pages, pvec.nr);
pagevec_release(&pvec);
cond_resched();
@@ -465,9 +400,9 @@
pagevec_init(&pvec, 0);
index = start;
while (index < end) {
- pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
- min(end - index, (pgoff_t)PAGEVEC_SIZE),
- pvec.pages, indices);
+ pvec.nr = find_get_entries(mapping, index,
+ min(end - index, (pgoff_t)PAGEVEC_SIZE),
+ pvec.pages, indices);
if (!pvec.nr)
break;
mem_cgroup_uncharge_start();
@@ -496,7 +431,7 @@
}
unlock_page(page);
}
- shmem_deswap_pagevec(&pvec);
+ pagevec_remove_exceptionals(&pvec);
pagevec_release(&pvec);
mem_cgroup_uncharge_end();
cond_resched();
@@ -534,9 +469,10 @@
index = start;
for ( ; ; ) {
cond_resched();
- pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
+
+ pvec.nr = find_get_entries(mapping, index,
min(end - index, (pgoff_t)PAGEVEC_SIZE),
- pvec.pages, indices);
+ pvec.pages, indices);
if (!pvec.nr) {
if (index == start || unfalloc)
break;
@@ -544,7 +480,7 @@
continue;
}
if ((index == start || unfalloc) && indices[0] >= end) {
- shmem_deswap_pagevec(&pvec);
+ pagevec_remove_exceptionals(&pvec);
pagevec_release(&pvec);
break;
}
@@ -573,7 +509,7 @@
}
unlock_page(page);
}
- shmem_deswap_pagevec(&pvec);
+ pagevec_remove_exceptionals(&pvec);
pagevec_release(&pvec);
mem_cgroup_uncharge_end();
index++;
@@ -1079,7 +1015,7 @@
return -EFBIG;
repeat:
swap.val = 0;
- page = find_lock_page(mapping, index);
+ page = find_lock_entry(mapping, index);
if (radix_tree_exceptional_entry(page)) {
swap = radix_to_swp_entry(page);
page = NULL;
@@ -1416,6 +1352,11 @@
return inode;
}
+bool shmem_mapping(struct address_space *mapping)
+{
+ return mapping->backing_dev_info == &shmem_backing_dev_info;
+}
+
#ifdef CONFIG_TMPFS
static const struct inode_operations shmem_symlink_inode_operations;
static const struct inode_operations shmem_short_symlink_operations;
@@ -1728,7 +1669,7 @@
pagevec_init(&pvec, 0);
pvec.nr = 1; /* start small: we may be there already */
while (!done) {
- pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
+ pvec.nr = find_get_entries(mapping, index,
pvec.nr, pvec.pages, indices);
if (!pvec.nr) {
if (whence == SEEK_DATA)
@@ -1755,7 +1696,7 @@
break;
}
}
- shmem_deswap_pagevec(&pvec);
+ pagevec_remove_exceptionals(&pvec);
pagevec_release(&pvec);
pvec.nr = PAGEVEC_SIZE;
cond_resched();