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Date: Fri, 18 Jan 2013 13:00:43 +0100
From: Jan Kara <jack@...e.cz>
To: Ted Tso <tytso@....edu>
Cc: linux-ext4@...r.kernel.org, Jan Kara <jack@...e.cz>
Subject: [PATCH 09/12] 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 <jack@...e.cz>
---
fs/ext4/inode.c | 145 ++++++++++++++-----------------------------------------
1 files changed, 36 insertions(+), 109 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 359d06e..0eb27e1 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 @@ out:
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 +2144,37 @@ 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--;
--
1.7.1
--
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