diff mbox

[3/3] ext3: Avoid starting a transaction in writepage when not necessary

Message ID 20090327222346.GJ31071@duck.suse.cz
State Not Applicable, archived
Headers show

Commit Message

Jan Kara March 27, 2009, 10:23 p.m. UTC 
On Fri 27-03-09 16:24:31, Theodore Ts'o wrote:
> From: Jan Kara <jack@suse.cz>
> 
> We don't have to start a transaction in writepage() when all the blocks
> are a properly allocated. Even in ordered mode either the data has been
> written via write() and they are thus already added to transaction's list
> or the data was written via mmap and then it's random in which transaction
> they get written anyway.
> 
> This should help VM to pageout dirty memory without blocking on transaction
> commits.
> 
> Signed-off-by: Jan Kara <jack@suse.cz>
> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  Please, use the patch below instead (and I'd also wait a few days for
Mingo to check whether it also helps him). It also changes data=writeback
mode in the same way and it adheres to coding style...

									Honza

Comments

Theodore Ts'o March 27, 2009, 11:03 p.m. UTC | #1 
On Fri, Mar 27, 2009 at 11:23:46PM +0100, Jan Kara wrote:
> On Fri 27-03-09 16:24:31, Theodore Ts'o wrote:
> > From: Jan Kara <jack@suse.cz>
> > 
> > We don't have to start a transaction in writepage() when all the blocks
> > are a properly allocated. Even in ordered mode either the data has been
> > written via write() and they are thus already added to transaction's list
> > or the data was written via mmap and then it's random in which transaction
> > they get written anyway.
> > 
> > This should help VM to pageout dirty memory without blocking on transaction
> > commits.
> > 
> > Signed-off-by: Jan Kara <jack@suse.cz>
> > Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
>   Please, use the patch below instead (and I'd also wait a few days for
> Mingo to check whether it also helps him). It also changes data=writeback
> mode in the same way and it adheres to coding style...

FYI, Looks like Linus has already cherry-picked your first patch from
LKML and dropped it into mainline.  My other two patches haven't gone
in yet as far as I can tell.

So we'll need to do a delta patch that has the differences from your
new patch and what Linus has already pulled into mainline.

    	      	   	     	     	    - Ted
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diff mbox

Patch

diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
index e230f7a..73f605a 100644
--- a/fs/ext3/inode.c
+++ b/fs/ext3/inode.c
@@ -1420,6 +1420,10 @@  static int bput_one(handle_t *handle, struct buffer_head *bh)
 	return 0;
 }
 
+static int buffer_unmapped(handle_t *handle, struct buffer_head *bh)
+{
+	return !buffer_mapped(bh);
+}
 /*
  * Note that we always start a transaction even if we're not journalling
  * data.  This is to preserve ordering: any hole instantiation within
@@ -1490,6 +1494,19 @@  static int ext3_ordered_writepage(struct page *page,
 	if (ext3_journal_current_handle())
 		goto out_fail;
 
+	if (!page_has_buffers(page)) {
+		create_empty_buffers(page, inode->i_sb->s_blocksize,
+				(1 << BH_Dirty)|(1 << BH_Uptodate));
+		page_bufs = page_buffers(page);
+	} else {
+		page_bufs = page_buffers(page);
+		if (!walk_page_buffers(NULL, page_bufs, 0, PAGE_CACHE_SIZE,
+				       NULL, buffer_unmapped)) {
+			/* Provide NULL get_block() to catch bugs if buffers
+			 * weren't really mapped */
+			return block_write_full_page(page, NULL, wbc);
+		}
+	}
 	handle = ext3_journal_start(inode, ext3_writepage_trans_blocks(inode));
 
 	if (IS_ERR(handle)) {
@@ -1497,11 +1514,6 @@  static int ext3_ordered_writepage(struct page *page,
 		goto out_fail;
 	}
 
-	if (!page_has_buffers(page)) {
-		create_empty_buffers(page, inode->i_sb->s_blocksize,
-				(1 << BH_Dirty)|(1 << BH_Uptodate));
-	}
-	page_bufs = page_buffers(page);
 	walk_page_buffers(handle, page_bufs, 0,
 			PAGE_CACHE_SIZE, NULL, bget_one);
 
@@ -1549,6 +1561,15 @@  static int ext3_writeback_writepage(struct page *page,
 	if (ext3_journal_current_handle())
 		goto out_fail;
 
+	if (page_has_buffers(page)) {
+		if (!walk_page_buffers(NULL, page_buffers(page), 0,
+				      PAGE_CACHE_SIZE, NULL, buffer_unmapped)) {
+			/* Provide NULL get_block() to catch bugs if buffers
+			 * weren't really mapped */
+			return block_write_full_page(page, NULL, wbc);
+		}
+	}
+
 	handle = ext3_journal_start(inode, ext3_writepage_trans_blocks(inode));
 	if (IS_ERR(handle)) {
 		ret = PTR_ERR(handle);