Messages in this thread Patch in this message | | | Date | Thu, 27 Jul 2006 12:19:45 +0200 | From | Nick Piggin <> | Subject | [patch] mm: non syncing lock_page |
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Sent this one a while back, but we decided it didn't need to be in 2.6.17. Any new comments on the patch?
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lock_page needs the caller to have a reference on the page->mapping inode due to sync_page, ergo set_page_dirty_lock is obviously buggy according to its comments.
Solve it by introducing a new lock_page_nosync which does not do a sync_page.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Index: linux-2.6/include/linux/pagemap.h =================================================================== --- linux-2.6.orig/include/linux/pagemap.h +++ linux-2.6/include/linux/pagemap.h @@ -130,14 +130,29 @@ static inline pgoff_t linear_page_index( } extern void FASTCALL(__lock_page(struct page *page)); +extern void FASTCALL(__lock_page_nosync(struct page *page)); extern void FASTCALL(unlock_page(struct page *page)); +/* + * lock_page may only be called if we have the page's inode pinned. + */ static inline void lock_page(struct page *page) { might_sleep(); if (TestSetPageLocked(page)) __lock_page(page); } + +/* + * lock_page_nosync should only be used if we can't pin the page's inode. + * Doesn't play quite so well with block device plugging. + */ +static inline void lock_page_nosync(struct page *page) +{ + might_sleep(); + if (TestSetPageLocked(page)) + __lock_page_nosync(page); +} /* * This is exported only for wait_on_page_locked/wait_on_page_writeback. Index: linux-2.6/mm/filemap.c =================================================================== --- linux-2.6.orig/mm/filemap.c +++ linux-2.6/mm/filemap.c @@ -488,6 +488,12 @@ struct page *page_cache_alloc_cold(struc EXPORT_SYMBOL(page_cache_alloc_cold); #endif +static int __sleep_on_page_lock(void *word) +{ + io_schedule(); + return 0; +} + /* * In order to wait for pages to become available there must be * waitqueues associated with pages. By using a hash table of @@ -577,6 +583,17 @@ void fastcall __lock_page(struct page *p } EXPORT_SYMBOL(__lock_page); +/* + * Variant of lock_page that does not require the caller to hold a reference + * on the page's mapping. + */ +void fastcall __lock_page_nosync(struct page *page) +{ + DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); + __wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock, + TASK_UNINTERRUPTIBLE); +} + /** * find_get_page - find and get a page reference * @mapping: the address_space to search Index: linux-2.6/mm/page-writeback.c =================================================================== --- linux-2.6.orig/mm/page-writeback.c +++ linux-2.6/mm/page-writeback.c @@ -690,7 +690,7 @@ int set_page_dirty_lock(struct page *pag { int ret; - lock_page(page); + lock_page_nosync(page); ret = set_page_dirty(page); unlock_page(page); return ret; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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