[linux-lvm] Question about VFS Locking patch, why is a change needed?
Steven Dake
sdake at mvista.com
Tue Apr 22 07:12:04 UTC 2003
Chris,
Thanks for the info !
-steve
Chris Mason wrote:
>On Thu, 2003-04-17 at 20:43, Steven Dake wrote:
>
>
>>Folks,
>>
>>I was analyzing the VFS locking patch and I wanted to know if someone
>>could explain the purpose of a change in the reiserfs for me:
>>
>>The change is:
>>Index: linus.21/fs/reiserfs/super.c
>>--- linus.21/fs/reiserfs/super.c Fri, 11 Jan 2002 10:14:59 -0500 root
>>(linux/41_super.c 1.2.2.1.2.1.1.1 644)
>>+++ linus.21(w)/fs/reiserfs/super.c Mon, 28 Jan 2002 13:50:56 -0500 root
>>(linux/41_super.c 1.2.2.1.2.1.1.1 644)
>>@@ -66,7 +66,7 @@
>> reiserfs_prepare_for_journal(s, SB_BUFFER_WITH_SB(s), 1);
>> journal_mark_dirty(&th, s, SB_BUFFER_WITH_SB (s));
>> reiserfs_block_writes(&th) ;
>>- journal_end(&th, s, 1) ;
>>+ journal_end_sync(&th, s, 1) ;
>> }
>> s->s_dirt = dirty;
>> unlock_kernel() ;
>>
>>I tried LVM with and without this change even under heavy load and LVM
>>can still create mountable snapshots of a reiser filesystem without the
>>change. Why is it there?
>>
>>
>
>journal_end will do an asynchronous commit, which means it won't wait
>for the journal to actually finish writing to disk. journal_end_sync
>will wait until the commit is fully on disk.
>
>In most cases, the reiserfs_block_writes call is sufficient and the
>journal_end_sync change isn't needed, but there are a few corner cases
>depending on the number of log writers where journal_end_sync is
>required.
>
>-chris
>
>
>
>_______________________________________________
>linux-lvm mailing list
>linux-lvm at sistina.com
>http://lists.sistina.com/mailman/listinfo/linux-lvm
>read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>
>
>
>
>
More information about the linux-lvm
mailing list