On Mon, Dec 07 2009 at 10:52am -0500, Mike Snitzer <snitzer@xxxxxxxxxx> wrote: > On Mon, Dec 07 2009 at 8:19am -0500, > Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote: > > > Hi > > > > This changes the timeout to a sequence count. And adds a comment. > > > > Mikulas > > > > --- > > > > Avoit the timeout. > > > > Use a sequence count to resolve the race. The count increases each time > > an exception reallocation finishes. Use wait_event() to wait until the count > > changes. > > > > The chunk-reallocation logic is explained in the comment in the patch. > > > > Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> > > Here is an updated patch that falls at the end of my snapshot-merge > series here: > http://people.redhat.com/msnitzer/patches/snapshot-merge/kernel/2.6.33/ > > --- > > dm snapshot: change the snapshot reallocation timeout to a sequence count > > Use a sequence count to resolve the race between I/O to chunks that are > about to be merged. The count increases each time an exception > reallocation finishes. Use wait_event() to wait until the count > changes. > > The chunk-reallocation logic is now explained in snapshot_merge_process() > > Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> > --- > drivers/md/dm-snap.c | 45 +++++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 43 insertions(+), 2 deletions(-) > > Index: linux-rhel6/drivers/md/dm-snap.c > =================================================================== > --- linux-rhel6.orig/drivers/md/dm-snap.c > +++ linux-rhel6/drivers/md/dm-snap.c > @@ -271,6 +271,8 @@ static struct list_head *_origins; > static struct rw_semaphore _origins_lock; > > static DECLARE_WAIT_QUEUE_HEAD(_pending_exception_done); > +static DEFINE_SPINLOCK(_pending_exception_done_spinlock); > +static u64 _pending_exception_done_count = 0; BTW, checkpatch issues the following error: ERROR: do not initialise statics to 0 or NULL #24: FILE: drivers/md/dm-snap.c:275: +static u64 _pending_exception_done_count = 0; -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
