Messages in this thread Patch in this message | | | Date | Fri, 18 Jul 2003 14:54:22 -0700 | From | Mark Fasheh <> | Subject | [PATCH-2.4] [RESEND] Fix deadlock in journal_create |
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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 */ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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