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Date: Sat, 12 Feb 2011 19:15:52 -0500
From: Theodore Ts'o <tytso@....edu>
To: Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc: Theodore Ts'o <tytso@....edu>
Subject: [PATCH,RFC 2/7] 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" <tytso@....edu>
---
fs/ext4/inode.c | 115 +++++++++++++++++++++++--------------------------------
1 files changed, 48 insertions(+), 67 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 627729f..e230f4f 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();
--
1.7.3.1
--
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