From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Howells Subject: [PATCH 11/14] FS-Cache: Release page->private in failed readahead [try #10] Date: Fri, 19 May 2006 16:47:08 +0100 Message-ID: <20060519154708.11791.66846.stgit@warthog.cambridge.redhat.com> References: <20060519154640.11791.2928.stgit@warthog.cambridge.redhat.com> Reply-To: Linux filesystem caching discussion list Cc: linux-fsdevel@vger.kernel.org, linux-cachefs@redhat.com, nfsv4@linux-nfs.org, linux-kernel@vger.kernel.org Return-path: To: torvalds@osdl.org, akpm@osdl.org, steved@redhat.com, trond.myklebust@fys.uio.no, aviro@redhat.com In-Reply-To: <20060519154640.11791.2928.stgit@warthog.cambridge.redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-cachefs-bounces@redhat.com Errors-To: linux-cachefs-bounces@redhat.com List-Id: linux-fsdevel.vger.kernel.org The attached patch causes read_cache_pages() to release page-private data on a page for which add_to_page_cache() fails or the filler function fails. This permits pages with caching references associated with them to be cleaned up. Further changes [try #9] that have been made: (*) The try_to_release_page() is called instead of calling the releasepage() op directly. (*) The page is locked before try_to_release_page() is called. (*) The call to try_to_release_page() and page_cache_release() have been abstracted out into a helper function as this bit of code occurs twice.. Further changes [try #10] that have been made: (*) The comment header on the helper function is much expanded. This states why there's a need to call the releasepage() op in the event of an error. (*) BUG() if the page is already locked when we try and lock it. (*) Don't set the page mapping pointer until we've locked the page. (*) The page is unlocked after try_to_release_page() is called. Signed-Off-By: David Howells --- mm/readahead.c | 25 +++++++++++++++++++++++-- 1 files changed, 23 insertions(+), 2 deletions(-) diff --git a/mm/readahead.c b/mm/readahead.c index 0f142a4..f9361f2 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -14,6 +14,7 @@ #include #include #include #include +#include void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page) { @@ -117,6 +118,26 @@ static inline unsigned long get_next_ra_ #define list_to_page(head) (list_entry((head)->prev, struct page, lru)) +/* + * see if a page needs releasing upon read_cache_pages() failure + * - the caller of read_cache_pages() may have set PG_private before calling, + * such as the NFS fs marking pages that are cached locally on disk, thus we + * need to give the fs a chance to clean up in the event of an error + */ +static inline void read_cache_pages_release_page(struct address_space *mapping, + struct page *page) +{ + if (PagePrivate(page)) { + if (TestSetPageLocked(page)) + BUG(); + page->mapping = mapping; + try_to_release_page(page, GFP_KERNEL); + page->mapping = NULL; + unlock_page(page); + } + page_cache_release(page); +} + /** * read_cache_pages - populate an address space with some pages, and * start reads against them. @@ -141,7 +162,7 @@ int read_cache_pages(struct address_spac page = list_to_page(pages); list_del(&page->lru); if (add_to_page_cache(page, mapping, page->index, GFP_KERNEL)) { - page_cache_release(page); + read_cache_pages_release_page(mapping, page); continue; } ret = filler(data, page); @@ -153,7 +174,7 @@ int read_cache_pages(struct address_spac victim = list_to_page(pages); list_del(&victim->lru); - page_cache_release(victim); + read_cache_pages_release_page(mapping, victim); } break; }