(2011/11/15 17:07), Yongqiang Yang wrote:
> delalloc blocks should be allocated before changing journal mode,
> otherwise they can not be allocated and even more truncate on
> delalloc blocks could triggre BUG by flushing delalloc buffers.
>
> Signed-off-by: Yongqiang Yang <xiaoqiangnk@xxxxxxxxx>
> ---
> fs/ext4/inode.c | 11 +++++++++++
> 1 files changed, 11 insertions(+), 0 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index de05e86..384f8a7 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -4676,6 +4676,17 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val)
> return 0;
> if (is_journal_aborted(journal))
> return -EROFS;
> + /* We have to allocate physical blocks for delalloc blocks
> + * before flushing journal. otherwise delalloc blocks can not
> + * be allocated any more. even more truncate on delalloc blocks
> + * could trigger BUG by flushing delalloc blocks in journal.
> + * There is no delalloc block in non-journal data mode.
> + */
> + if (val && test_opt(inode->i_sb, DELALLOC)) {
> + err = ext4_alloc_da_blocks(inode);
> + if (err < 0)
> + return err;
> + }
>
> jbd2_journal_lock_updates(journal);
> jbd2_journal_flush(journal);
Though I tested your patch by my reproducer that caused a panic which you
pointed out, a panic did not happen.
-------------------------------------------------------------------------------
#!/bin/sh
echo "a" > /tmp/a # file under an ext4 filesystem
chattr +j /tmp/a
echo "a" >> /tmp/a
chattr -j /tmp/a
-------------------------------------------------------------------------------
So, this patch looks good to me.
Tested-by: Toshiyuki Okajima <toshi.okajima@xxxxxxxxxxxxxx>
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