[PATCH] splice: LRU fixups

Nick says that the current construct isn't safe. This goes back to the
original, but sets PIPE_BUF_FLAG_LRU on user pages as well as they all
seem to be on the LRU in the first place.

Signed-off-by: Jens Axboe <axboe@suse.de>

diff --git a/fs/splice.c b/fs/splice.c
index 27f5e37..0b20242 100644 (file)
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -78,6 +78,7 @@ static int page_cache_pipe_buf_steal(struct pipe_inode_info *info,
                return 1;
        }
 
+       buf->flags |= PIPE_BUF_FLAG_LRU;
        return 0;
 }
 
@@ -85,6 +86,7 @@ static void page_cache_pipe_buf_release(struct pipe_inode_info *info,
                                        struct pipe_buffer *buf)
 {
        page_cache_release(buf->page);
+       buf->flags &= ~PIPE_BUF_FLAG_LRU;
 }
 
 static int page_cache_pipe_buf_pin(struct pipe_inode_info *info,
@@ -141,6 +143,7 @@ static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe,
        if (!(buf->flags & PIPE_BUF_FLAG_GIFT))
                return 1;
 
+       buf->flags |= PIPE_BUF_FLAG_LRU;
        return generic_pipe_buf_steal(pipe, buf);
 }
 
@@ -566,37 +569,23 @@ static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf,
         */
        if ((sd->flags & SPLICE_F_MOVE) && this_len == PAGE_CACHE_SIZE) {
                /*
-                * If steal succeeds, buf->page is now pruned from the vm
-                * side (page cache) and we can reuse it. The page will also
-                * be locked on successful return.
+                * If steal succeeds, buf->page is now pruned from the
+                * pagecache and we can reuse it. The page will also be
+                * locked on successful return.
                 */
                if (buf->ops->steal(info, buf))
                        goto find_page;
 
                page = buf->page;
-               page_cache_get(page);
-
-               /*
-                * page must be on the LRU for adding to the pagecache.
-                * Check this without grabbing the zone lock, if it isn't
-                * the do grab the zone lock, recheck, and add if necessary.
-                */
-               if (!PageLRU(page)) {
-                       struct zone *zone = page_zone(page);
-
-                       spin_lock_irq(&zone->lru_lock);
-                       if (!PageLRU(page)) {
-                               SetPageLRU(page);
-                               add_page_to_inactive_list(zone, page);
-                       }
-                       spin_unlock_irq(&zone->lru_lock);
-               }
-
                if (add_to_page_cache(page, mapping, index, gfp_mask)) {
-                       page_cache_release(page);
                        unlock_page(page);
                        goto find_page;
                }
+
+               page_cache_get(page);
+
+               if (!(buf->flags & PIPE_BUF_FLAG_LRU))
+                       lru_cache_add(page);
        } else {
 find_page:
                page = find_lock_page(mapping, index);

diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index ba73108..ea4f7cd 100644 (file)
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -5,8 +5,9 @@
 
 #define PIPE_BUFFERS (16)
 
-#define PIPE_BUF_FLAG_ATOMIC   0x01    /* was atomically mapped */
-#define PIPE_BUF_FLAG_GIFT     0x02    /* page is a gift */
+#define PIPE_BUF_FLAG_LRU      0x01    /* page is on the LRU */
+#define PIPE_BUF_FLAG_ATOMIC   0x02    /* was atomically mapped */
+#define PIPE_BUF_FLAG_GIFT     0x04    /* page is a gift */
 
 struct pipe_buffer {
        struct page *page;