[PATCH] splice: fix page stealing LRU handling.
Originally from Nick Piggin, just adapted to the newer branch.
You can't check PageLRU without holding zone->lru_lock. The page
release code can get away with it only because the page refcount is 0 at
that point. Also, you can't reliably remove pages from the LRU unless
the refcount is 0. Ever.
Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Jens Axboe <axboe@suse.de>
diff --git a/fs/splice.c b/fs/splice.c
index b5fb2f3..bfa42a2 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -67,16 +67,7 @@
if (!remove_mapping(mapping, page))
return 1;
- if (PageLRU(page)) {
- struct zone *zone = page_zone(page);
-
- spin_lock_irq(&zone->lru_lock);
- BUG_ON(!PageLRU(page));
- __ClearPageLRU(page);
- del_page_from_lru(zone, page);
- spin_unlock_irq(&zone->lru_lock);
- }
-
+ buf->flags |= PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU;
return 0;
}
@@ -85,6 +76,7 @@
{
page_cache_release(buf->page);
buf->page = NULL;
+ buf->flags &= ~(PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU);
}
static void *page_cache_pipe_buf_map(struct file *file,
@@ -414,11 +406,12 @@
{
struct file *file = sd->file;
struct address_space *mapping = file->f_mapping;
+ gfp_t gfp_mask = mapping_gfp_mask(mapping);
unsigned int offset;
struct page *page;
pgoff_t index;
char *src;
- int ret, stolen;
+ int ret;
/*
* after this, page will be locked and unmapped
@@ -429,7 +422,6 @@
index = sd->pos >> PAGE_CACHE_SHIFT;
offset = sd->pos & ~PAGE_CACHE_MASK;
- stolen = 0;
/*
* reuse buf page, if SPLICE_F_MOVE is set
@@ -443,15 +435,15 @@
goto find_page;
page = buf->page;
- stolen = 1;
- if (add_to_page_cache_lru(page, mapping, index,
- mapping_gfp_mask(mapping)))
+ if (add_to_page_cache(page, mapping, index, gfp_mask))
goto find_page;
+
+ if (!(buf->flags & PIPE_BUF_FLAG_LRU))
+ lru_cache_add(page);
} else {
find_page:
ret = -ENOMEM;
- page = find_or_create_page(mapping, index,
- mapping_gfp_mask(mapping));
+ page = find_or_create_page(mapping, index, gfp_mask);
if (!page)
goto out;
@@ -494,7 +486,7 @@
} else if (ret)
goto out;
- if (!stolen) {
+ if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) {
char *dst = kmap_atomic(page, KM_USER0);
memcpy(dst + offset, src + buf->offset, sd->len);
@@ -511,7 +503,7 @@
balance_dirty_pages_ratelimited(mapping);
out:
- if (!stolen) {
+ if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) {
page_cache_release(page);
unlock_page(page);
}