From: Mark Fasheh <mark.fasheh@oracle.com>
To: marcelo@conectiva.com.br
Cc: sct@redhat.com, linux-kernel@vger.kernel.org
Subject: [PATCH-2.4] [RESEND] Fix deadlock in journal_create
Date: Fri, 18 Jul 2003 14:54:22 -0700 [thread overview]
Message-ID: <20030718215421.GF1014@ca-server1.us.oracle.com> (raw)
Marcelo,
I sent this initially against 2.4.21-rc6 and it didn't make it in
-- even though it got Stephen's OK. Here's a resend -- I've identified that
the bug still exists and 2.4.22-pre7. The patch didn't need to be changed as
it still applies cleanly.
I ran across a deadlock 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 trivial patch to fix this is attached.
--Mark
--
Mark Fasheh
Software Developer, Oracle Corp
mark.fasheh@oracle.com
--- linux-2.4.22-pre7/fs/jbd/journal.c.orig 2003-05-30 11:49:10.000000000 -0700
+++ linux-2.4.22-pre7/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 */
next reply other threads:[~2003-07-18 21:41 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-07-18 21:54 Mark Fasheh [this message]
2003-07-22 1:34 ` [PATCH-2.4] [RESEND] Fix deadlock in journal_create Stephen C. Tweedie
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