Hi,
I ran across a deadlock yesterday when trying to do a journal_create
at mount time. The problem is that journal_create does a sync_dev which
eventually tries to do a get_super which does:
down_read(&s->s_umount);
The problem arises if I call journal_create from my read_super method in
which case get_sb_bdev has already done:
down_write(&s->s_umount);
from alloc_super. Replacing the sync_dev call with an fsync_no_super seems
to have fixed the deadlock.
It you want to test this out using ext3 (I have verified it with my own
filesystem), simply follow these steps:
1) create an ext2 filesystem on a device
2) mount that new partition and make a "journal file" on it (using dd).
get the inode number of that file.
3) unmount it and remount it as an ext3 filesystem using the option:
journal=inode_number where inode number is the inode number of the journal
file you just created.
This will get ext3's read_super method to call ext3_create_journal which
will hang during a journal_create.
A one line patch is attached. Please let me know what you think.
--Mark
--
Mark Fasheh
Software Developer, Oracle Corp
[email protected]
--- linux-2.4.21-rc6/fs/jbd/journal.c.orig 2003-05-30 11:49:10.000000000 -0700
+++ linux-2.4.21-rc6/fs/jbd/journal.c 2003-05-30 11:49:18.000000000 -0700
@@ -912,7 +912,7 @@ int journal_create(journal_t *journal)
__brelse(bh);
}
- sync_dev(journal->j_dev);
+ fsync_no_super(journal->j_dev);
jbd_debug(1, "JBD: journal cleared.\n");
/* OK, fill in the initial static fields in the new superblock */
Hi,
On Fri, 2003-05-30 at 22:31, Mark Fasheh wrote:
> This will get ext3's read_super method to call ext3_create_journal which
> will hang during a journal_create.
>
> A one line patch is attached. Please let me know what you think.
Looks OK to me.
--Stephen