On Monday 04 February 2008 5:12:28 am Aneesh Kumar K.V wrote:
> Hi,
>
> This is with the new ext3 -> ext4 migrate code added. The recently added
> lockdep for jbd2 helped to find this out. We want to hold the i_data_sem
> on the ext3 inode during migration to prevent walking the ext3 inode
> when it is being converted to ext4 format. Also we want to avoid
> file truncation and new blocks being added while converting to ext4.
> Also we dont want to reserve large number of credits for journal.
> Any idea how to fix this ?
>
Hello,
Seems you should be taking the i_data_sem after starting the journal in
ext4_ext_migrate. I haven't looked at this stuff too much, but everywhere I
see i_data_sem taken its within a journal_start/journal_stop. Here's the
patch. Let me know if I'm way off btw, like I said I'm new to this :). Thank
you,
Josef
Index: linux-2.6/fs/ext4/migrate.c
===================================================================
--- linux-2.6.orig/fs/ext4/migrate.c
+++ linux-2.6/fs/ext4/migrate.c
@@ -414,7 +414,6 @@ int ext4_ext_migrate(struct inode *inode
if ((EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
return -EINVAL;
- down_write(&EXT4_I(inode)->i_data_sem);
handle = ext4_journal_start(inode,
EXT4_DATA_TRANS_BLOCKS(inode->i_sb) +
EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3 +
@@ -424,6 +423,9 @@ int ext4_ext_migrate(struct inode *inode
retval = PTR_ERR(handle);
goto err_out;
}
+
+ down_write(&EXT4_I(inode)->i_data_sem);
+
tmp_inode = ext4_new_inode(handle,
inode->i_sb->s_root->d_inode,
S_IFREG);
@@ -549,10 +551,10 @@ err_out:
*/
tmp_inode->i_nlink = 0;
- ext4_journal_stop(handle);
-
up_write(&EXT4_I(inode)->i_data_sem);
+ ext4_journal_stop(handle);
+
if (tmp_inode)
iput(tmp_inode);
-
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