From 3e7ee3e7b36fa4e2d88d8fb0a2577be95fc4636d Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Sun, 2 Apr 2006 23:11:04 +0200 Subject: [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 Signed-off-by: Jens Axboe --- fs/splice.c | 30 +++++++++++------------------- 1 file changed, 11 insertions(+), 19 deletions(-) (limited to 'fs/splice.c') 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 @@ static int page_cache_pipe_buf_steal(struct pipe_inode_info *info, 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 @@ static void page_cache_pipe_buf_release(struct pipe_inode_info *info, { 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 @@ static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf, { 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 @@ static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf, 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 @@ static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf, 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 @@ find_page: } 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 @@ find_page: balance_dirty_pages_ratelimited(mapping); out: - if (!stolen) { + if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) { page_cache_release(page); unlock_page(page); } -- cgit v1.1