Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422693AbWHXVex (ORCPT ); Thu, 24 Aug 2006 17:34:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1422721AbWHXVd7 (ORCPT ); Thu, 24 Aug 2006 17:33:59 -0400 Received: from mx1.redhat.com ([66.187.233.31]:10980 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S1422693AbWHXVdN (ORCPT ); Thu, 24 Aug 2006 17:33:13 -0400 From: David Howells Subject: [PATCH 08/17] BLOCK: Dissociate generic_writepages() from mpage stuff [try #2] Date: Thu, 24 Aug 2006 22:33:11 +0100 To: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Cc: dhowells@redhat.com Message-Id: <20060824213310.21323.91875.stgit@warthog.cambridge.redhat.com> In-Reply-To: <20060824213252.21323.18226.stgit@warthog.cambridge.redhat.com> References: <20060824213252.21323.18226.stgit@warthog.cambridge.redhat.com> Content-Type: text/plain; charset=utf-8; format=fixed Content-Transfer-Encoding: 8bit User-Agent: StGIT/0.10 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7177 Lines: 231 From: David Howells Dissociate the generic_writepages() function from the mpage stuff, moving its declaration to linux/mm.h and actually emitting a full implementation into mm/page-writeback.c. The implementation is a partial duplicate of mpage_writepages() with all BIO references removed. It is used by NFS to do writeback. Signed-Off-By: David Howells --- fs/block_dev.c | 1 fs/mpage.c | 2 + include/linux/mpage.h | 6 -- include/linux/writeback.h | 2 + mm/page-writeback.c | 135 +++++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 140 insertions(+), 6 deletions(-) diff --git a/fs/block_dev.c b/fs/block_dev.c index 3753457..8debde8 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -17,6 +17,7 @@ #include #include #include #include +#include #include #include #include diff --git a/fs/mpage.c b/fs/mpage.c index 1e45982..6792251 100644 --- a/fs/mpage.c +++ b/fs/mpage.c @@ -693,6 +693,8 @@ out: * the call was made get new I/O started against them. If wbc->sync_mode is * WB_SYNC_ALL then we were called for data integrity and we must wait for * existing IO to complete. + * + * !!!! If you fix this you should check generic_writepages() also!!!! */ int mpage_writepages(struct address_space *mapping, diff --git a/include/linux/mpage.h b/include/linux/mpage.h index 3ca8804..517c098 100644 --- a/include/linux/mpage.h +++ b/include/linux/mpage.h @@ -20,9 +20,3 @@ int mpage_writepages(struct address_spac struct writeback_control *wbc, get_block_t get_block); int mpage_writepage(struct page *page, get_block_t *get_block, struct writeback_control *wbc); - -static inline int -generic_writepages(struct address_space *mapping, struct writeback_control *wbc) -{ - return mpage_writepages(mapping, wbc, NULL); -} diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 9e38b56..671c43b 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -110,6 +110,8 @@ balance_dirty_pages_ratelimited(struct a } int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0); +extern int generic_writepages(struct address_space *mapping, + struct writeback_control *wbc); int do_writepages(struct address_space *mapping, struct writeback_control *wbc); int sync_page_range(struct inode *inode, struct address_space *mapping, loff_t pos, loff_t count); diff --git a/mm/page-writeback.c b/mm/page-writeback.c index f75d033..668716c 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -30,6 +30,7 @@ #include #include #include #include +#include /* * The maximum number of pages to writeout in a single bdflush/kupdate @@ -543,6 +544,140 @@ void __init page_writeback_init(void) register_cpu_notifier(&ratelimit_nb); } +/** + * generic_writepages - walk the list of dirty pages of the given + * address space and writepage() all of them. + * + * @mapping: address space structure to write + * @wbc: subtract the number of written pages from *@wbc->nr_to_write + * + * This is a library function, which implements the writepages() + * address_space_operation. + * + * If a page is already under I/O, generic_writepages() skips it, even + * if it's dirty. This is desirable behaviour for memory-cleaning writeback, + * but it is INCORRECT for data-integrity system calls such as fsync(). fsync() + * and msync() need to guarantee that all the data which was dirty at the time + * the call was made get new I/O started against them. If wbc->sync_mode is + * WB_SYNC_ALL then we were called for data integrity and we must wait for + * existing IO to complete. + * + * !!!! Derived from mpage_writepages() - if you fix this you should check that + * also !!!! + */ +int generic_writepages(struct address_space *mapping, + struct writeback_control *wbc) +{ + struct backing_dev_info *bdi = mapping->backing_dev_info; + int ret = 0; + int done = 0; + int (*writepage)(struct page *page, struct writeback_control *wbc); + struct pagevec pvec; + int nr_pages; + pgoff_t index; + pgoff_t end; /* Inclusive */ + int scanned = 0; + int range_whole = 0; + + if (wbc->nonblocking && bdi_write_congested(bdi)) { + wbc->encountered_congestion = 1; + return 0; + } + + writepage = mapping->a_ops->writepage; + + /* deal with chardevs and other special file */ + if (!writepage) + return 0; + + pagevec_init(&pvec, 0); + if (wbc->range_cyclic) { + index = mapping->writeback_index; /* Start from prev offset */ + end = -1; + } else { + index = wbc->range_start >> PAGE_CACHE_SHIFT; + end = wbc->range_end >> PAGE_CACHE_SHIFT; + if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) + range_whole = 1; + scanned = 1; + } +retry: + while (!done && (index <= end) && + (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, + PAGECACHE_TAG_DIRTY, + min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) { + unsigned i; + + scanned = 1; + for (i = 0; i < nr_pages; i++) { + struct page *page = pvec.pages[i]; + + /* + * At this point we hold neither mapping->tree_lock nor + * lock on the page itself: the page may be truncated or + * invalidated (changing page->mapping to NULL), or even + * swizzled back from swapper_space to tmpfs file + * mapping + */ + + lock_page(page); + + if (unlikely(page->mapping != mapping)) { + unlock_page(page); + continue; + } + + if (!wbc->range_cyclic && page->index > end) { + done = 1; + unlock_page(page); + continue; + } + + if (wbc->sync_mode != WB_SYNC_NONE) + wait_on_page_writeback(page); + + if (PageWriteback(page) || + !clear_page_dirty_for_io(page)) { + unlock_page(page); + continue; + } + + ret = (*writepage)(page, wbc); + if (ret) { + if (ret == -ENOSPC) + set_bit(AS_ENOSPC, &mapping->flags); + else + set_bit(AS_EIO, &mapping->flags); + } + + if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE)) + unlock_page(page); + if (ret || (--(wbc->nr_to_write) <= 0)) + done = 1; + if (wbc->nonblocking && bdi_write_congested(bdi)) { + wbc->encountered_congestion = 1; + done = 1; + } + } + pagevec_release(&pvec); + cond_resched(); + } + if (!scanned && !done) { + /* + * We hit the last page and there is more work to be done: wrap + * back to the start of the file + */ + scanned = 1; + index = 0; + goto retry; + } + if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0)) + mapping->writeback_index = index; + return ret; +} + +EXPORT_SYMBOL(generic_writepages); + int do_writepages(struct address_space *mapping, struct writeback_control *wbc) { int 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/