On Thu, Feb 03, 2005 at 07:51:37AM -0800, Badari Pulavarty wrote:
> On Wed, 2005-02-02 at 12:19, Sonny Rao wrote:
> > On Wed, Feb 02, 2005 at 07:32:04AM -0800, Badari Pulavarty wrote:
> > > Hi,
> > >
> > > I forgot the reason why we don't have ext3_writepages() ?
> > > I can dig through to find out, but it would be easy to ask
> > > people.
> > >
> > > Please let me know.
> >
> > Badari, I seem to have successfully hacked the writeback mode to use
> > writepages on a User-Mode Linux instance. I'm going to try it on a
> > real box soon. The only issue is that pdflush is passing the create
> > parameter as 1 to writepages, which doesn't exactly make sense. I
> > suppose it might be needed for a filesystem like XFS which does
> > delayed block allocation ? In ext3 however, the blocks should have
> > been allocated beforehand.
>
> Funny, I am also hacking writepages for writeback mode. You are a step
> ahead of me :) Please let me know, how it goes.
Well it seems to work, here's my (rather ugly) patch.
I'm doing some performance comparisons now.
Sonny
diff -Naurp linux-2.6.10-original/fs/ext3/inode.c
linux-2.6.10-working/fs/ext3/inode.c
--- linux-2.6.10-original/fs/ext3/inode.c 2004-12-24 15:35:01.000000000
-0600
+++ linux-2.6.10-working/fs/ext3/inode.c 2005-01-29 10:45:09.599837136
-0600
@@ -810,6 +810,18 @@ static int ext3_get_block(struct inode *
return ret;
}
+static int ext3_get_block_wpages(struct inode *inode, sector_t iblock,
+ struct buffer_head *bh_result, int create)
+{
+ /* ugly hack, just pass 0 tfor create to get_block_handle */
+ /* the blocks shouldd have already been allocated ifwe're in */
+ /* writepages writeback */
+ return ext3_get_block_handle(NULL, inode, iblock,
+ bh_result, 0, 0);
+}
+
+
+
#define DIO_CREDITS (EXT3_RESERVE_TRANS_BLOCKS + 32)
static int
@@ -1025,6 +1037,32 @@ out:
return ret;
}
+static int ext3_nobh_prepare_write(struct file *file, struct page *page,
+ unsigned from, unsigned to)
+{
+ struct inode *inode = page->mapping->host;
+ int ret;
+ int needed_blocks = ext3_writepage_trans_blocks(inode);
+ handle_t *handle;
+ int retries = 0;
+
+retry:
+ handle = ext3_journal_start(inode, needed_blocks);
+ if (IS_ERR(handle)) {
+ ret = PTR_ERR(handle);
+ goto out;
+ }
+ ret = nobh_prepare_write(page, from, to, ext3_get_block);
+ if (ret)
+ ext3_journal_stop(handle);
+ if (ret == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
+ goto retry;
+out:
+
+ return ret;
+}
+
+
static int
ext3_journal_dirty_data(handle_t *handle, struct buffer_head *bh)
{
@@ -1092,7 +1130,7 @@ static int ext3_writeback_commit_write(s
new_i_size = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
if (new_i_size > EXT3_I(inode)->i_disksize)
EXT3_I(inode)->i_disksize = new_i_size;
- ret = generic_commit_write(file, page, from, to);
+ ret = nobh_commit_write(file, page, from, to);
ret2 = ext3_journal_stop(handle);
if (!ret)
ret = ret2;
@@ -1321,6 +1359,14 @@ out_fail:
return ret;
}
+static int
+ext3_writeback_writepages(struct address_space *mapping,
+ struct writeback_control *wbc)
+{
+ return mpage_writepages(mapping, wbc, ext3_get_block_wpages);
+}
+
+
static int ext3_writeback_writepage(struct page *page,
struct writeback_control *wbc)
{
@@ -1552,8 +1598,9 @@ static struct address_space_operations e
.readpage = ext3_readpage,
.readpages = ext3_readpages,
.writepage = ext3_writeback_writepage,
+ .writepages = ext3_writeback_writepages,
.sync_page = block_sync_page,
- .prepare_write = ext3_prepare_write,
+ .prepare_write = ext3_nobh_prepare_write,
.commit_write = ext3_writeback_commit_write,
.bmap = ext3_bmap,
.invalidatepage = ext3_invalidatepage,
