From cf32bd9c86b6917d8446c00ea0081dde6e716a82 Mon Sep 17 00:00:00 2001 From: Ilya Dryomov Date: Mon, 19 Jan 2015 22:57:39 +0300 Subject: [PATCH] rbd: do not treat standalone as flatten If the clone is resized down to 0, it becomes standalone. If such resize is carried over while an image is mapped we would detect this and call rbd_dev_parent_put() which means "let go of all parent state, including the spec(s) of parent images(s)". This leads to a mismatch between "rbd info" and sysfs parent fields, so a fix is in order. # rbd create --image-format 2 --size 1 foo # rbd snap create foo@snap # rbd snap protect foo@snap # rbd clone foo@snap bar # DEV=$(rbd map bar) # rbd resize --allow-shrink --size 0 bar # rbd resize --size 1 bar # rbd info bar | grep parent parent: rbd/foo@snap Before: # cat /sys/bus/rbd/devices/0/parent (no parent image) After: # cat /sys/bus/rbd/devices/0/parent pool_id 0 pool_name rbd image_id 10056b8b4567 image_name foo snap_id 2 snap_name snap overlap 0 Signed-off-by: Ilya Dryomov Reviewed-by: Josh Durgin Reviewed-by: Alex Elder --- drivers/block/rbd.c | 30 ++++++++++-------------------- 1 file changed, 10 insertions(+), 20 deletions(-) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index b85d52005a21..e818c2a6ffb1 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -4273,32 +4273,22 @@ static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev) } /* - * We always update the parent overlap. If it's zero we - * treat it specially. + * We always update the parent overlap. If it's zero we issue + * a warning, as we will proceed as if there was no parent. */ - rbd_dev->parent_overlap = overlap; if (!overlap) { - - /* A null parent_spec indicates it's the initial probe */ - if (parent_spec) { - /* - * The overlap has become zero, so the clone - * must have been resized down to 0 at some - * point. Treat this the same as a flatten. - */ - rbd_dev_parent_put(rbd_dev); - pr_info("%s: clone image now standalone\n", - rbd_dev->disk->disk_name); + /* refresh, careful to warn just once */ + if (rbd_dev->parent_overlap) + rbd_warn(rbd_dev, + "clone now standalone (overlap became 0)"); } else { - /* - * For the initial probe, if we find the - * overlap is zero we just pretend there was - * no parent image. - */ - rbd_warn(rbd_dev, "ignoring parent with overlap 0"); + /* initial probe */ + rbd_warn(rbd_dev, "clone is standalone (overlap 0)"); } } + rbd_dev->parent_overlap = overlap; + out: ret = 0; out_err: