Re: Ext4 tree backports for 2.6.27.13 and 2.6.28.2

Chuck Ebbert
2009-02-11T20:36:20Z

On Wed, 11 Feb 2009 13:29:14 +0530
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> wrote:

> On Sat, Jan 31, 2009 at 12:25:39AM -0500, Theodore Ts'o wrote:
> > I've updated the ext4 backport branches on the ext4 git tree:
> >
> > git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git
> > http://git.kernel.org/?p=linux/kernel/git/tytso/ext4.git
> >
> > The for-stable branch is branched off of 2.6.28.2, and has a candidate
> > set of patches to be included in the next stable release. The
> > for-stable-2.6.27 branch is branched off of 2.6.27.13.
> >
> > I'm more confident with the 2.6.28 stable candidate than the 2.6.27
> > stable candidates at the moment, but given that we just missed the
> > 2.6.27.14 and 2.6.28.3 release cycles, that should give us plenty of
> > time to test the patches.
> >
> > - Ted
> >
> >
> > 8556e8f3 18d5cb0 fd3bd090
> > ext4: Don't allow new groups to be added during block allocation
> >
>
> This commit on for-stable-2.6.27 is not complete.
> ac->alloc_semp is not assigned in the code.
>

I think this fixes that one:

Add missing pieces to the below patch in the 2.6.27 ext4 patchset.
http://git.kernel.org/?p=linux/kernel/git/tytso/ext4.git;a=commitdiff;h=fd3bd090d7cc93292d3fa361b9c323752417bd7b
"ext4: Don't allow new groups to be added during block allocation"

Signed-off-by: Chuck Ebbert <cebbert@redhat.com>

Index: linux-2.6.27.noarch/fs/ext4/mballoc.c
===================================================================
--- linux-2.6.27.noarch.orig/fs/ext4/mballoc.c
+++ linux-2.6.27.noarch/fs/ext4/mballoc.c
@@ -1055,7 +1055,8 @@ static void ext4_mb_release_desc(struct
if (e4b->bd_buddy_page)
page_cache_release(e4b->bd_buddy_page);
/* Done with the buddy cache */
- up_read(e4b->alloc_semp);
+ if (e4b->alloc_semp)
+ up_read(e4b->alloc_semp);
}

@@ -1375,6 +1376,9 @@ static void ext4_mb_use_best_found(struc
get_page(ac->ac_bitmap_page);
ac->ac_buddy_page = e4b->bd_buddy_page;
get_page(ac->ac_buddy_page);
+ /* on allocation we use ac to track the held semaphore */
+ ac->alloc_semp = e4b->alloc_semp;
+ e4b->alloc_semp = NULL;
/* store last allocated for subsequent stream allocation */
if ((ac->ac_flags & EXT4_MB_HINT_DATA)) {
spin_lock(&sbi->s_md_lock);