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memfd: Convert memfd_tag_pins to XArray 

Switch to a batch-processing model like memfd_wait_for_pins() and
use the xa_state previously set up by memfd_wait_for_pins().

Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
This commit is contained in:
Matthew Wilcox 2017-11-22 08:37:38 -05:00
parent 2313216f86
commit ef3038a573
1 changed files with 17 additions and 25 deletions
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42
mm/memfd.c
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@ -28,37 +28,29 @@
#define MEMFD_TAG_PINNED PAGECACHE_TAG_TOWRITE #define MEMFD_TAG_PINNED PAGECACHE_TAG_TOWRITE
#define LAST_SCAN 4 /* about 150ms max */ #define LAST_SCAN 4 /* about 150ms max */
static void memfd_tag_pins(struct address_space *mapping) static void memfd_tag_pins(struct xa_state *xas)
{ {
struct radix_tree_iter iter;
void __rcu **slot;
pgoff_t start;
struct page *page; struct page *page;
unsigned int tagged = 0;
lru_add_drain(); lru_add_drain();
start = 0;
rcu_read_lock();
radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start) { xas_lock_irq(xas);
page = radix_tree_deref_slot(slot); xas_for_each(xas, page, ULONG_MAX) {
if (!page || radix_tree_exception(page)) { if (xa_is_value(page))
if (radix_tree_deref_retry(page)) { continue;
slot = radix_tree_iter_retry(&iter); if (page_count(page) - page_mapcount(page) > 1)
continue; xas_set_mark(xas, MEMFD_TAG_PINNED);
}
} else if (page_count(page) - page_mapcount(page) > 1) {
xa_lock_irq(&mapping->i_pages);
radix_tree_tag_set(&mapping->i_pages, iter.index,
MEMFD_TAG_PINNED);
xa_unlock_irq(&mapping->i_pages);
}
if (need_resched()) { if (++tagged % XA_CHECK_SCHED)
slot = radix_tree_iter_resume(slot, &iter); continue;
cond_resched_rcu();
} xas_pause(xas);
xas_unlock_irq(xas);
cond_resched();
xas_lock_irq(xas);
} }
rcu_read_unlock(); xas_unlock_irq(xas);
} }
/* /*
@ -76,7 +68,7 @@ static int memfd_wait_for_pins(struct address_space *mapping)
struct page *page; struct page *page;
int error, scan; int error, scan;
memfd_tag_pins(mapping); memfd_tag_pins(&xas);
error = 0; error = 0;
for (scan = 0; scan <= LAST_SCAN; scan++) { for (scan = 0; scan <= LAST_SCAN; scan++) {