From 4f01b02c8c4e4111bd1adbcafb5741e8e991f5fd Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Sat, 26 Feb 2011 14:07:37 -0500 Subject: [PATCH] ext4: simple cleanups to write_cache_pages_da() Eliminate duplicate code, unneeded variables, etc., to make it easier to understand the code. No behavioral changes were made in this patch. Signed-off-by: "Theodore Ts'o" --- fs/ext4/inode.c | 115 ++++++++++++++++++++---------------------------- 1 file changed, 48 insertions(+), 67 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index fcd08ca0643b..1e718e87f466 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -2723,17 +2723,14 @@ static int write_cache_pages_da(struct address_space *mapping, struct mpage_da_data *mpd, pgoff_t *done_index) { - struct inode *inode = mpd->inode; - struct buffer_head *bh, *head; - sector_t logical; - int ret = 0; - int done = 0; - struct pagevec pvec; - unsigned nr_pages; - pgoff_t index; - pgoff_t end; /* Inclusive */ - long nr_to_write = wbc->nr_to_write; - int tag; + struct buffer_head *bh, *head; + struct inode *inode = mpd->inode; + struct pagevec pvec; + unsigned int nr_pages; + sector_t logical; + pgoff_t index, end; + long nr_to_write = wbc->nr_to_write; + int i, tag, ret = 0; pagevec_init(&pvec, 0); index = wbc->range_start >> PAGE_CACHE_SHIFT; @@ -2745,13 +2742,11 @@ static int write_cache_pages_da(struct address_space *mapping, tag = PAGECACHE_TAG_DIRTY; *done_index = index; - while (!done && (index <= end)) { - int i; - + while (index <= end) { nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag, min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1); if (nr_pages == 0) - break; + return 0; for (i = 0; i < nr_pages; i++) { struct page *page = pvec.pages[i]; @@ -2763,47 +2758,37 @@ static int write_cache_pages_da(struct address_space *mapping, * mapping. However, page->index will not change * because we have a reference on the page. */ - if (page->index > end) { - done = 1; - break; - } + if (page->index > end) + goto out; *done_index = page->index + 1; lock_page(page); /* - * Page truncated or invalidated. We can freely skip it - * then, even for data integrity operations: the page - * has disappeared concurrently, so there could be no - * real expectation of this data interity operation - * even if there is now a new, dirty page at the same - * pagecache address. + * If the page is no longer dirty, or its + * mapping no longer corresponds to inode we + * are writing (which means it has been + * truncated or invalidated), or the page is + * already under writeback and we are not + * doing a data integrity writeback, skip the page */ - if (unlikely(page->mapping != mapping)) { -continue_unlock: + if (!PageDirty(page) || + (PageWriteback(page) && + (wbc->sync_mode == WB_SYNC_NONE)) || + unlikely(page->mapping != mapping)) { + continue_unlock: unlock_page(page); continue; } - if (!PageDirty(page)) { - /* someone wrote it for us */ - goto continue_unlock; - } - - if (PageWriteback(page)) { - if (wbc->sync_mode != WB_SYNC_NONE) - wait_on_page_writeback(page); - else - goto continue_unlock; - } + if (PageWriteback(page)) + wait_on_page_writeback(page); BUG_ON(PageWriteback(page)); if (!clear_page_dirty_for_io(page)) goto continue_unlock; - /* BEGIN __mpage_da_writepage */ - /* * Can we merge this page to current extent? */ @@ -2820,8 +2805,7 @@ continue_unlock: */ redirty_page_for_writepage(wbc, page); unlock_page(page); - ret = MPAGE_DA_EXTENT_TAIL; - goto out; + goto ret_extent_tail; } /* @@ -2838,15 +2822,15 @@ continue_unlock: (PAGE_CACHE_SHIFT - inode->i_blkbits); if (!page_has_buffers(page)) { - mpage_add_bh_to_extent(mpd, logical, PAGE_CACHE_SIZE, + mpage_add_bh_to_extent(mpd, logical, + PAGE_CACHE_SIZE, (1 << BH_Dirty) | (1 << BH_Uptodate)); - if (mpd->io_done) { - ret = MPAGE_DA_EXTENT_TAIL; - goto out; - } + if (mpd->io_done) + goto ret_extent_tail; } else { /* - * Page with regular buffer heads, just add all dirty ones + * Page with regular buffer heads, + * just add all dirty ones */ head = page_buffers(page); bh = head; @@ -2862,18 +2846,19 @@ continue_unlock: mpage_add_bh_to_extent(mpd, logical, bh->b_size, bh->b_state); - if (mpd->io_done) { - ret = MPAGE_DA_EXTENT_TAIL; - goto out; - } + if (mpd->io_done) + goto ret_extent_tail; } else if (buffer_dirty(bh) && (buffer_mapped(bh))) { /* - * mapped dirty buffer. We need to update - * the b_state because we look at - * b_state in mpage_da_map_blocks. We don't - * update b_size because if we find an - * unmapped buffer_head later we need to - * use the b_state flag of that buffer_head. + * mapped dirty buffer. We need + * to update the b_state + * because we look at b_state + * in mpage_da_map_blocks. We + * don't update b_size because + * if we find an unmapped + * buffer_head later we need to + * use the b_state flag of that + * buffer_head. */ if (mpd->b_size == 0) mpd->b_state = bh->b_state & BH_FLAGS; @@ -2882,14 +2867,10 @@ continue_unlock: } while ((bh = bh->b_this_page) != head); } - ret = 0; - - /* END __mpage_da_writepage */ - if (nr_to_write > 0) { nr_to_write--; if (nr_to_write == 0 && - wbc->sync_mode == WB_SYNC_NONE) { + wbc->sync_mode == WB_SYNC_NONE) /* * We stop writing back only if we are * not doing integrity sync. In case of @@ -2900,15 +2881,15 @@ continue_unlock: * pages, but have not synced all of the * old dirty pages. */ - done = 1; - break; - } + goto out; } } pagevec_release(&pvec); cond_resched(); } - return ret; + return 0; +ret_extent_tail: + ret = MPAGE_DA_EXTENT_TAIL; out: pagevec_release(&pvec); cond_resched(); -- 2.39.5