From f8bec37037aceb126d695c021cf4dc93b7238d47 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 28 Jan 2013 12:55:08 -0500 Subject: [PATCH] ext4: dirty page has always buffers attached ext4_writepage(), write_cache_pages_da(), and mpage_da_submit_io() doesn't have to deal with the case when page doesn't have buffers. We attach buffers to a page in ->write_begin() and ->page_mkwrite() which covers all places where a page can become dirty. Signed-off-by: Jan Kara Signed-off-by: "Theodore Ts'o" --- fs/ext4/inode.c | 147 +++++++++++++----------------------------------- 1 file changed, 38 insertions(+), 109 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index cbbf58327a29..8a89cbbf0f1a 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -132,8 +132,6 @@ static inline int ext4_begin_ordered_truncate(struct inode *inode, } static void ext4_invalidatepage(struct page *page, unsigned long offset); -static int noalloc_get_block_write(struct inode *inode, sector_t iblock, - struct buffer_head *bh_result, int create); static int __ext4_journalled_writepage(struct page *page, unsigned int len); static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh); static int ext4_discard_partial_page_buffers_no_lock(handle_t *handle, @@ -1374,7 +1372,7 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd, if (nr_pages == 0) break; for (i = 0; i < nr_pages; i++) { - int commit_write = 0, skip_page = 0; + int skip_page = 0; struct page *page = pvec.pages[i]; index = page->index; @@ -1396,27 +1394,9 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd, BUG_ON(!PageLocked(page)); BUG_ON(PageWriteback(page)); - /* - * If the page does not have buffers (for - * whatever reason), try to create them using - * __block_write_begin. If this fails, - * skip the page and move on. - */ - if (!page_has_buffers(page)) { - if (__block_write_begin(page, 0, len, - noalloc_get_block_write)) { - skip_page: - unlock_page(page); - continue; - } - commit_write = 1; - } - bh = page_bufs = page_buffers(page); block_start = 0; do { - if (!bh) - goto skip_page; if (map && (cur_logical >= map->m_lblk) && (cur_logical <= (map->m_lblk + (map->m_len - 1)))) { @@ -1444,12 +1424,10 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd, pblock++; } while (bh != page_bufs); - if (skip_page) - goto skip_page; - - if (commit_write) - /* mark the buffer_heads as dirty & uptodate */ - block_commit_write(page, 0, len); + if (skip_page) { + unlock_page(page); + continue; + } clear_page_dirty_for_io(page); err = ext4_bio_write_page(&io_submit, page, len, @@ -1869,27 +1847,6 @@ int ext4_da_get_block_prep(struct inode *inode, sector_t iblock, return 0; } -/* - * This function is used as a standard get_block_t calback function when there - * is no desire to allocate any blocks. It is used as a callback function for - * block_write_begin(). These functions should only try to map a single block - * at a time. - * - * Since this function doesn't do block allocations even if the caller - * requests it by passing in create=1, it is critically important that - * any caller checks to make sure that any buffer heads are returned - * by this function are either all already mapped or marked for - * delayed allocation before calling ext4_bio_write_page(). Otherwise, - * b_blocknr could be left unitialized, and the page write functions will - * be taken by surprise. - */ -static int noalloc_get_block_write(struct inode *inode, sector_t iblock, - struct buffer_head *bh_result, int create) -{ - BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize); - return _ext4_get_block(inode, iblock, bh_result, 0); -} - static int bget_one(handle_t *handle, struct buffer_head *bh) { get_bh(bh); @@ -2014,7 +1971,7 @@ static int __ext4_journalled_writepage(struct page *page, static int ext4_writepage(struct page *page, struct writeback_control *wbc) { - int ret = 0, commit_write = 0; + int ret = 0; loff_t size; unsigned int len; struct buffer_head *page_bufs = NULL; @@ -2028,21 +1985,6 @@ static int ext4_writepage(struct page *page, else len = PAGE_CACHE_SIZE; - /* - * If the page does not have buffers (for whatever reason), - * try to create them using __block_write_begin. If this - * fails, redirty the page and move on. - */ - if (!page_has_buffers(page)) { - if (__block_write_begin(page, 0, len, - noalloc_get_block_write)) { - redirty_page: - redirty_page_for_writepage(wbc, page); - unlock_page(page); - return 0; - } - commit_write = 1; - } page_bufs = page_buffers(page); if (ext4_walk_page_buffers(NULL, page_bufs, 0, len, NULL, ext4_bh_delay_or_unwritten)) { @@ -2056,11 +1998,10 @@ static int ext4_writepage(struct page *page, */ WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD)) == PF_MEMALLOC); - goto redirty_page; + redirty_page_for_writepage(wbc, page); + unlock_page(page); + return 0; } - if (commit_write) - /* now mark the buffer_heads as dirty and uptodate */ - block_commit_write(page, 0, len); if (PageChecked(page) && ext4_should_journal_data(inode)) /* @@ -2203,51 +2144,39 @@ static int write_cache_pages_da(handle_t *handle, logical = (sector_t) page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); - if (!page_has_buffers(page)) { - mpage_add_bh_to_extent(mpd, logical, - PAGE_CACHE_SIZE, - (1 << BH_Dirty) | (1 << BH_Uptodate)); - if (mpd->io_done) - goto ret_extent_tail; - } else { + /* Add all dirty buffers to mpd */ + head = page_buffers(page); + bh = head; + do { + BUG_ON(buffer_locked(bh)); /* - * Page with regular buffer heads, - * just add all dirty ones + * We need to try to allocate unmapped blocks + * in the same page. Otherwise we won't make + * progress with the page in ext4_writepage */ - head = page_buffers(page); - bh = head; - do { - BUG_ON(buffer_locked(bh)); + if (ext4_bh_delay_or_unwritten(NULL, bh)) { + mpage_add_bh_to_extent(mpd, logical, + bh->b_size, + bh->b_state); + if (mpd->io_done) + goto ret_extent_tail; + } else if (buffer_dirty(bh) && + buffer_mapped(bh)) { /* - * We need to try to allocate - * unmapped blocks in the same page. - * Otherwise we won't make progress - * with the page in ext4_writepage + * 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 (ext4_bh_delay_or_unwritten(NULL, bh)) { - mpage_add_bh_to_extent(mpd, logical, - bh->b_size, - bh->b_state); - 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. - */ - if (mpd->b_size == 0) - mpd->b_state = bh->b_state & BH_FLAGS; - } - logical++; - } while ((bh = bh->b_this_page) != head); - } + if (mpd->b_size == 0) + mpd->b_state = + bh->b_state & BH_FLAGS; + } + logical++; + } while ((bh = bh->b_this_page) != head); if (nr_to_write > 0) { nr_to_write--;