From 6fe6900e1e5b6fa9e5c59aa5061f244fe3f467e2 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Sun, 6 May 2007 14:49:04 -0700 Subject: mm: make read_cache_page synchronous Ensure pages are uptodate after returning from read_cache_page, which allows us to cut out most of the filesystem-internal PageUptodate calls. I didn't have a great look down the call chains, but this appears to fixes 7 possible use-before uptodate in hfs, 2 in hfsplus, 1 in jfs, a few in ecryptfs, 1 in jffs2, and a possible cleared data overwritten with readpage in block2mtd. All depending on whether the filler is async and/or can return with a !uptodate page. Signed-off-by: Nick Piggin Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/filemap.c | 49 ++++++++++++++++++++++++++++++++++++++----------- mm/swapfile.c | 3 --- 2 files changed, 38 insertions(+), 14 deletions(-) (limited to 'mm') diff --git a/mm/filemap.c b/mm/filemap.c index 5dfc093ceb3..070e7547d5b 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1726,7 +1726,7 @@ int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma) EXPORT_SYMBOL(generic_file_mmap); EXPORT_SYMBOL(generic_file_readonly_mmap); -static inline struct page *__read_cache_page(struct address_space *mapping, +static struct page *__read_cache_page(struct address_space *mapping, unsigned long index, int (*filler)(void *,struct page*), void *data) @@ -1763,17 +1763,11 @@ repeat: return page; } -/** - * read_cache_page - read into page cache, fill it if needed - * @mapping: the page's address_space - * @index: the page index - * @filler: function to perform the read - * @data: destination for read data - * - * Read into the page cache. If a page already exists, - * and PageUptodate() is not set, try to fill the page. +/* + * Same as read_cache_page, but don't wait for page to become unlocked + * after submitting it to the filler. */ -struct page *read_cache_page(struct address_space *mapping, +struct page *read_cache_page_async(struct address_space *mapping, unsigned long index, int (*filler)(void *,struct page*), void *data) @@ -1804,6 +1798,39 @@ retry: page_cache_release(page); page = ERR_PTR(err); } + out: + mark_page_accessed(page); + return page; +} +EXPORT_SYMBOL(read_cache_page_async); + +/** + * read_cache_page - read into page cache, fill it if needed + * @mapping: the page's address_space + * @index: the page index + * @filler: function to perform the read + * @data: destination for read data + * + * Read into the page cache. If a page already exists, and PageUptodate() is + * not set, try to fill the page then wait for it to become unlocked. + * + * If the page does not get brought uptodate, return -EIO. + */ +struct page *read_cache_page(struct address_space *mapping, + unsigned long index, + int (*filler)(void *,struct page*), + void *data) +{ + struct page *page; + + page = read_cache_page_async(mapping, index, filler, data); + if (IS_ERR(page)) + goto out; + wait_on_page_locked(page); + if (!PageUptodate(page)) { + page_cache_release(page); + page = ERR_PTR(-EIO); + } out: return page; } diff --git a/mm/swapfile.c b/mm/swapfile.c index a2d9bb4e80d..acc172cbe3a 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1531,9 +1531,6 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags) error = PTR_ERR(page); goto bad_swap; } - wait_on_page_locked(page); - if (!PageUptodate(page)) - goto bad_swap; kmap(page); swap_header = page_address(page); -- cgit v1.2.3