Commit 54b02eb0 authored by Anton Altaparmakov's avatar Anton Altaparmakov
Browse files

NTFS: Optimize fs/ntfs/aops.c::ntfs_write_block() by extending the page 


      lock protection over the buffer submission for i/o which allows the
      removal of the get_bh()/put_bh() pairs for each buffer.

Signed-off-by: default avatarAnton Altaparmakov <aia21@cantab.net>
parent bd45fdd2

fs/ntfs/ChangeLog

+3 −0
Original line number Diff line number Diff line
@@ -81,6 +81,9 @@ ToDo/Notes: 
	  only zeroes.

	- Fixup handling of sparse, compressed, and encrypted attributes in

	  fs/ntfs/aops.c::ntfs_writepage().

	- Optimize fs/ntfs/aops.c::ntfs_write_block() by extending the page

	  lock protection over the buffer submission for i/o which allows the

	  removal of the get_bh()/put_bh() pairs for each buffer.



2.1.23 - Implement extension of resident files and make writing safe as well as

	 many bug fixes, cleanups, and enhancements...

fs/ntfs/aops.c

+3 −10
Original line number Diff line number Diff line
@@ -735,7 +735,7 @@ static int ntfs_write_block(struct page *page, struct writeback_control *wbc) 
	/* For the error case, need to reset bh to the beginning. */

	bh = head;



	/* Just an optimization, so ->readpage() isn't called later. */

	/* Just an optimization, so ->readpage() is not called later. */

	if (unlikely(!PageUptodate(page))) {

		int uptodate = 1;

		do {
@@ -751,7 +751,6 @@ static int ntfs_write_block(struct page *page, struct writeback_control *wbc) 


	/* Setup all mapped, dirty buffers for async write i/o. */

	do {

		get_bh(bh);

		if (buffer_mapped(bh) && buffer_dirty(bh)) {

			lock_buffer(bh);

			if (test_clear_buffer_dirty(bh)) {
@@ -789,14 +788,8 @@ static int ntfs_write_block(struct page *page, struct writeback_control *wbc) 


	BUG_ON(PageWriteback(page));

	set_page_writeback(page);	/* Keeps try_to_free_buffers() away. */

	unlock_page(page);



	/*

	 * Submit the prepared buffers for i/o. Note the page is unlocked,

	 * and the async write i/o completion handler can end_page_writeback()

	 * at any time after the *first* submit_bh(). So the buffers can then

	 * disappear...

	 */

	/* Submit the prepared buffers for i/o. */

	need_end_writeback = TRUE;

	do {

		struct buffer_head *next = bh->b_this_page;
@@ -804,9 +797,9 @@ static int ntfs_write_block(struct page *page, struct writeback_control *wbc) 
			submit_bh(WRITE, bh);

			need_end_writeback = FALSE;

		}

		put_bh(bh);

		bh = next;

	} while (bh != head);

	unlock_page(page);



	/* If no i/o was started, need to end_page_writeback(). */

	if (unlikely(need_end_writeback))