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ext4: simple cleanups to write_cache_pages_da()
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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" <[email protected]>
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@tytso
tytso committed Feb 26, 2011
1 parent 8eb9e5c commit 4f01b02
Showing 1 changed file with 48 additions and 67 deletions.
115 changes: 48 additions & 67 deletions fs/ext4/inode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -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];
Expand All @@ -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?
*/
Expand All @@ -2820,8 +2805,7 @@ static int write_cache_pages_da(struct address_space *mapping,
*/
redirty_page_for_writepage(wbc, page);
unlock_page(page);
ret = MPAGE_DA_EXTENT_TAIL;
goto out;
goto ret_extent_tail;
}

/*
Expand All @@ -2838,15 +2822,15 @@ static int write_cache_pages_da(struct address_space *mapping,
(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;
Expand All @@ -2862,18 +2846,19 @@ static int write_cache_pages_da(struct address_space *mapping,
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;
Expand All @@ -2882,14 +2867,10 @@ static int write_cache_pages_da(struct address_space *mapping,
} 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
Expand All @@ -2900,15 +2881,15 @@ static int write_cache_pages_da(struct address_space *mapping,
* 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();
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