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Date: Thu, 20 Mar 2008 11:09:02 +0530
From: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To: Mingming Cao <cmm@...ibm.com>
Cc: Eric Sandeen <sandeen@...hat.com>,
ext4 <linux-ext4@...r.kernel.org>
Subject: Re: BUG with delayed allocation
On Wed, Mar 19, 2008 at 05:46:58PM -0700, Mingming Cao wrote:
> On Wed, 2008-03-19 at 14:22 +0530, Aneesh Kumar K.V wrote:
> > Hi,
> >
> > Eric actually observed it yesterday. I am able to reproduce it locally.
> > With delayed allocation we are observing wrong value of i_size.
> >
>
> The problem is current delalloc does not update on-disk i_size until
> writeout time, the in-core i_size is updated though.
>
ext4_da_writepages actually update the i_disksize during writeout time.
The writepage callback for delalloc was using ext4_writeback_writepage,
which didn't update the i_disksize. That is why some of the files have
correct size while some doesn't. I tested the below change and sent this
to list. But i appears vger dropped the mail to the list.
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 79930df..b74426d 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1488,6 +1488,43 @@ out:
return ret;
}
+static int ext4_da_writepage(struct page *page,
+ struct writeback_control *wbc)
+{
+ struct inode *inode = page->mapping->host;
+ handle_t *handle = NULL;
+ int ret = 0;
+ int err;
+
+ if (ext4_journal_current_handle())
+ goto out_fail;
+
+ handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
+ if (IS_ERR(handle)) {
+ ret = PTR_ERR(handle);
+ goto out_fail;
+ }
+
+ if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode))
+ ret = nobh_writepage(page, ext4_get_block, wbc);
+ else
+ ret = block_write_full_page(page, ext4_get_block, wbc);
+
+ if (!ret && inode->i_size > EXT4_I(inode)->i_disksize) {
+ EXT4_I(inode)->i_disksize = inode->i_size;
+ ext4_mark_inode_dirty(handle, inode);
+ }
+
+ err = ext4_journal_stop(handle);
+ if (!ret)
+ ret = err;
+ return ret;
+
+out_fail:
+ redirty_page_for_writepage(wbc, page);
+ unlock_page(page);
+ return ret;
+}
static int ext4_da_writepages(struct address_space *mapping,
struct writeback_control *wbc)
@@ -2015,7 +2052,7 @@ static const struct address_space_operations ext4_journalled_aops = {
static const struct address_space_operations ext4_da_aops = {
.readpage = ext4_readpage,
.readpages = ext4_readpages,
- .writepage = ext4_writeback_writepage,
+ .writepage = ext4_da_writepage,
.writepages = ext4_da_writepages,
.sync_page = block_sync_page,
.write_begin = ext4_da_write_begin,
> Could you try the following patch? It updates the i_disksize at the
> write_end time.
>
I will test the patch and update you. BTW shouldn't we update
i_disksize only after actual block got allocated ?
>
> Signed-off-by: Mingming Cao <cmm@...ibm.com>
> ---
> fs/ext4/inode.c | 39 ++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 38 insertions(+), 1 deletion(-)
>
> Index: linux-2.6.25-rc5/fs/ext4/inode.c
> ===================================================================
> --- linux-2.6.25-rc5.orig/fs/ext4/inode.c 2008-03-19 17:32:44.000000000 -0700
> +++ linux-2.6.25-rc5/fs/ext4/inode.c 2008-03-19 17:43:19.000000000 -0700
> @@ -1355,6 +1355,43 @@ static int ext4_writeback_write_end(stru
> return ret ? ret : copied;
> }
>
> +static int ext4_da_write_end(struct file *file,
> + struct address_space *mapping,
> + loff_t pos, unsigned len, unsigned copied,
> + struct page *page, void *fsdata)
> +{
> + handle_t *handle;
> + struct inode *inode = file->f_mapping->host;
> + int needed_blocks = ext4_writepage_trans_blocks(inode);
> + int ret = 0, ret2;
> + loff_t new_i_size;
> +
> + handle = ext4_journal_start(inode, needed_blocks);
> + if (IS_ERR(handle)) {
> + unlock_page(page);
> + page_cache_release(page);
> + ret = PTR_ERR(handle);
> + return ret;
> + }
> +
> + new_i_size = pos + copied;
> + if (new_i_size > EXT4_I(inode)->i_disksize)
> + EXT4_I(inode)->i_disksize = new_i_size;
> +
> + copied = ext4_generic_write_end(file, mapping, pos, len, copied,
> + page, fsdata);
> + if (copied < 0)
> + ret = copied;
> +
> + ret2 = ext4_journal_stop(handle);
> + if (!ret)
> + ret = ret2;
> + unlock_page(page);
> + page_cache_release(page);
> +
> + return ret ? ret : copied;
> +}
> +
> static int ext4_journalled_write_end(struct file *file,
> struct address_space *mapping,
> loff_t pos, unsigned len, unsigned copied,
> @@ -2020,7 +2057,7 @@ static const struct address_space_operat
> .writepages = ext4_da_writepages,
> .sync_page = block_sync_page,
> .write_begin = ext4_da_write_begin,
> - .write_end = generic_write_end,
> + .write_end = ext4_da_write_end,
> .bmap = ext4_bmap,
> .invalidatepage = ext4_da_invalidatepage,
> .releasepage = ext4_releasepage,
>
>
-aneesh
--
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