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Message-Id: <1297556157-21559-2-git-send-email-tytso@mit.edu>
Date: Sat, 12 Feb 2011 19:15:51 -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 1/7] ext4: fold __mpage_da_writepage() into write_cache_pages_da()
Fold the __mpage_da_writepage() function into write_cache_pages_da().
This will give us opportunities to clean up and simplify the resulting
code.
Signed-off-by: "Theodore Ts'o" <tytso@....edu>
---
fs/ext4/inode.c | 206 ++++++++++++++++++++++++-------------------------------
1 files changed, 91 insertions(+), 115 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9f7f9e4..627729f 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2438,102 +2438,6 @@ static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh)
}
/*
- * __mpage_da_writepage - finds extent of pages and blocks
- *
- * @page: page to consider
- * @wbc: not used, we just follow rules
- * @data: context
- *
- * The function finds extents of pages and scan them for all blocks.
- */
-static int __mpage_da_writepage(struct page *page,
- struct writeback_control *wbc,
- struct mpage_da_data *mpd)
-{
- struct inode *inode = mpd->inode;
- struct buffer_head *bh, *head;
- sector_t logical;
-
- /*
- * Can we merge this page to current extent?
- */
- if (mpd->next_page != page->index) {
- /*
- * Nope, we can't. So, we map non-allocated blocks
- * and start IO on them
- */
- if (mpd->next_page != mpd->first_page) {
- mpage_da_map_and_submit(mpd);
- /*
- * skip rest of the page in the page_vec
- */
- redirty_page_for_writepage(wbc, page);
- unlock_page(page);
- return MPAGE_DA_EXTENT_TAIL;
- }
-
- /*
- * Start next extent of pages ...
- */
- mpd->first_page = page->index;
-
- /*
- * ... and blocks
- */
- mpd->b_size = 0;
- mpd->b_state = 0;
- mpd->b_blocknr = 0;
- }
-
- mpd->next_page = page->index + 1;
- 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)
- return MPAGE_DA_EXTENT_TAIL;
- } else {
- /*
- * Page with regular buffer heads, just add all dirty ones
- */
- head = page_buffers(page);
- bh = head;
- do {
- BUG_ON(buffer_locked(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
- */
- 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)
- return MPAGE_DA_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);
- }
-
- return 0;
-}
-
-/*
* This is a special get_blocks_t callback which is used by
* ext4_da_write_begin(). It will either return mapped block or
* reserve space for a single block.
@@ -2811,18 +2715,17 @@ static int ext4_da_writepages_trans_blocks(struct inode *inode)
/*
* write_cache_pages_da - walk the list of dirty pages of the given
- * address space and call the callback function (which usually writes
- * the pages).
- *
- * This is a forked version of write_cache_pages(). Differences:
- * Range cyclic is ignored.
- * no_nrwrite_index_update is always presumed true
+ * address space and accumulate pages that need writing, and call
+ * mpage_da_map_and_submit to map the pages and then write them.
*/
static int write_cache_pages_da(struct address_space *mapping,
struct writeback_control *wbc,
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;
@@ -2899,17 +2802,90 @@ continue_unlock:
if (!clear_page_dirty_for_io(page))
goto continue_unlock;
- ret = __mpage_da_writepage(page, wbc, mpd);
- if (unlikely(ret)) {
- if (ret == AOP_WRITEPAGE_ACTIVATE) {
+ /* BEGIN __mpage_da_writepage */
+
+ /*
+ * Can we merge this page to current extent?
+ */
+ if (mpd->next_page != page->index) {
+ /*
+ * Nope, we can't. So, we map
+ * non-allocated blocks and start IO
+ * on them
+ */
+ if (mpd->next_page != mpd->first_page) {
+ mpage_da_map_and_submit(mpd);
+ /*
+ * skip rest of the page in the page_vec
+ */
+ redirty_page_for_writepage(wbc, page);
unlock_page(page);
- ret = 0;
- } else {
- done = 1;
- break;
+ ret = MPAGE_DA_EXTENT_TAIL;
+ goto out;
+ }
+
+ /*
+ * Start next extent of pages and blocks
+ */
+ mpd->first_page = page->index;
+ mpd->b_size = 0;
+ mpd->b_state = 0;
+ mpd->b_blocknr = 0;
+ }
+
+ mpd->next_page = page->index + 1;
+ 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) {
+ ret = MPAGE_DA_EXTENT_TAIL;
+ goto out;
}
+ } else {
+ /*
+ * Page with regular buffer heads, just add all dirty ones
+ */
+ head = page_buffers(page);
+ bh = head;
+ do {
+ BUG_ON(buffer_locked(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
+ */
+ 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) {
+ ret = MPAGE_DA_EXTENT_TAIL;
+ goto out;
+ }
+ } 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);
}
+ ret = 0;
+
+ /* END __mpage_da_writepage */
+
if (nr_to_write > 0) {
nr_to_write--;
if (nr_to_write == 0 &&
@@ -2933,6 +2909,10 @@ continue_unlock:
cond_resched();
}
return ret;
+out:
+ pagevec_release(&pvec);
+ cond_resched();
+ return ret;
}
@@ -3059,13 +3039,9 @@ retry:
}
/*
- * Now call __mpage_da_writepage to find the next
+ * Now call write_cache_pages_da() to find the next
* contiguous region of logical blocks that need
- * blocks to be allocated by ext4. We don't actually
- * submit the blocks for I/O here, even though
- * write_cache_pages thinks it will, and will set the
- * pages as clean for write before calling
- * __mpage_da_writepage().
+ * blocks to be allocated by ext4 and submit them.
*/
mpd.b_size = 0;
mpd.b_state = 0;
--
1.7.3.1
--
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