Hi, On Thu, 2004-04-01 at 10:40, Scorpion Yang wrote: > why is there a window between statements "err = > ext3_journal_get_write_access(handle, this_bh);" and > "ext3_journal_dirty_metadata(handle, this_bh);" ? That's the whole point of the journaling mechanism. To modify a block of metadata on the ext3 filesystem, you need to get write access first, then change the buffer, then queue the changes for the journal. There *has* to be a window between getting the write access and committing it, because that's the window where the buffer is allowed to be changed! The issue is that ext3 tries to do zero-copy writing of metadata to the journal whenever possible. So, a given buffer_head at some point in time might actually be waiting to be written to the journal. To maintain journal integrity, we cannot touch that data --- so we need to do a "get_write_access()" first so that the jbd layer can copy out the data that's destined for the journal. The caller can then safely modify the primary contents of the buffer_head. > In my test, there is an error in journal_dirty_metadata: jh is null In what context? Cheers, Stephen _______________________________________________ Ext3-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ext3-users
