From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josh Durgin Subject: Re: [PATCH 3/6] rbd: get parent spec for version 2 images Date: Wed, 31 Oct 2012 18:33:16 -0700 Message-ID: <5091D15C.9000804@inktank.com> References: <509081C4.3050402@inktank.com> <509083A3.5030003@inktank.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-pa0-f46.google.com ([209.85.220.46]:39813 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754479Ab2KABda (ORCPT ); Wed, 31 Oct 2012 21:33:30 -0400 Received: by mail-pa0-f46.google.com with SMTP id hz1so1360244pad.19 for ; Wed, 31 Oct 2012 18:33:29 -0700 (PDT) In-Reply-To: <509083A3.5030003@inktank.com> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Alex Elder Cc: ceph-devel Reviewed-by: Josh Durgin On 10/30/2012 06:49 PM, Alex Elder wrote: > Add support for getting the the information identifying the parent > image for rbd images that have them. The child image holds a > reference to its parent image specification structure. Create a new > entry "parent" in /sys/bus/rbd/image/N/ to report the identifying > information for the parent image, if any. > > Signed-off-by: Alex Elder > --- > Documentation/ABI/testing/sysfs-bus-rbd | 4 + > drivers/block/rbd.c | 131 > +++++++++++++++++++++++++++++++ > include/linux/ceph/rados.h | 2 + > 3 files changed, 137 insertions(+) > > diff --git a/Documentation/ABI/testing/sysfs-bus-rbd > b/Documentation/ABI/testing/sysfs-bus-rbd > index 1cf2adf..cd9213c 100644 > --- a/Documentation/ABI/testing/sysfs-bus-rbd > +++ b/Documentation/ABI/testing/sysfs-bus-rbd > @@ -70,6 +70,10 @@ snap_* > > A directory per each snapshot > > +parent > + > + Information identifying the pool, image, and snapshot id for > + the parent image in a layered rbd image (format 2 only). > > Entries under /sys/bus/rbd/devices//snap_ > ------------------------------------------------------------- > diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c > index 28052ff..bce1fcf 100644 > --- a/drivers/block/rbd.c > +++ b/drivers/block/rbd.c > @@ -217,6 +217,9 @@ struct rbd_device { > struct ceph_osd_event *watch_event; > struct ceph_osd_request *watch_request; > > + struct rbd_spec *parent_spec; > + u64 parent_overlap; > + > /* protects updating the header */ > struct rw_semaphore header_rwsem; > > @@ -2009,6 +2012,49 @@ static ssize_t rbd_snap_show(struct device *dev, > return sprintf(buf, "%s\n", rbd_dev->spec->snap_name); > } > > +/* > + * For an rbd v2 image, shows the pool id, image id, and snapshot id > + * for the parent image. If there is no parent, simply shows > + * "(no parent image)". > + */ > +static ssize_t rbd_parent_show(struct device *dev, > + struct device_attribute *attr, > + char *buf) > +{ > + struct rbd_device *rbd_dev = dev_to_rbd_dev(dev); > + struct rbd_spec *spec = rbd_dev->parent_spec; > + int count; > + char *bufp = buf; > + > + if (!spec) > + return sprintf(buf, "(no parent image)\n"); > + > + count = sprintf(bufp, "pool_id %llu\npool_name %s\n", > + (unsigned long long) spec->pool_id, spec->pool_name); > + if (count < 0) > + return count; > + bufp += count; > + > + count = sprintf(bufp, "image_id %s\nimage_name %s\n", spec->image_id, > + spec->image_name ? spec->image_name : "(unknown)"); > + if (count < 0) > + return count; > + bufp += count; > + > + count = sprintf(bufp, "snap_id %llu\nsnap_name %s\n", > + (unsigned long long) spec->snap_id, spec->snap_name); > + if (count < 0) > + return count; > + bufp += count; > + > + count = sprintf(bufp, "overlap %llu\n", rbd_dev->parent_overlap); > + if (count < 0) > + return count; > + bufp += count; > + > + return (ssize_t) (bufp - buf); > +} > + > static ssize_t rbd_image_refresh(struct device *dev, > struct device_attribute *attr, > const char *buf, > @@ -2032,6 +2078,7 @@ static DEVICE_ATTR(name, S_IRUGO, rbd_name_show, > NULL); > static DEVICE_ATTR(image_id, S_IRUGO, rbd_image_id_show, NULL); > static DEVICE_ATTR(refresh, S_IWUSR, NULL, rbd_image_refresh); > static DEVICE_ATTR(current_snap, S_IRUGO, rbd_snap_show, NULL); > +static DEVICE_ATTR(parent, S_IRUGO, rbd_parent_show, NULL); > > static struct attribute *rbd_attrs[] = { > &dev_attr_size.attr, > @@ -2043,6 +2090,7 @@ static struct attribute *rbd_attrs[] = { > &dev_attr_name.attr, > &dev_attr_image_id.attr, > &dev_attr_current_snap.attr, > + &dev_attr_parent.attr, > &dev_attr_refresh.attr, > NULL > }; > @@ -2192,6 +2240,7 @@ struct rbd_device *rbd_dev_create(struct > rbd_client *rbdc, > > static void rbd_dev_destroy(struct rbd_device *rbd_dev) > { > + rbd_spec_put(rbd_dev->parent_spec); > kfree(rbd_dev->header_name); > rbd_put_client(rbd_dev->rbd_client); > rbd_spec_put(rbd_dev->spec); > @@ -2400,6 +2449,71 @@ static int rbd_dev_v2_features(struct rbd_device > *rbd_dev) > &rbd_dev->header.features); > } > > +static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev) > +{ > + struct rbd_spec *parent_spec; > + size_t size; > + void *reply_buf = NULL; > + __le64 snapid; > + void *p; > + void *end; > + char *image_id; > + u64 overlap; > + size_t len = 0; > + int ret; > + > + parent_spec = rbd_spec_alloc(); > + if (!parent_spec) > + return -ENOMEM; > + > + size = sizeof (__le64) + /* pool_id */ > + sizeof (__le32) + RBD_IMAGE_ID_LEN_MAX + /* image_id */ > + sizeof (__le64) + /* snap_id */ > + sizeof (__le64); /* overlap */ > + reply_buf = kmalloc(size, GFP_KERNEL); > + if (!reply_buf) { > + ret = -ENOMEM; > + goto out_err; > + } > + > + snapid = cpu_to_le64(CEPH_NOSNAP); > + ret = rbd_req_sync_exec(rbd_dev, rbd_dev->header_name, > + "rbd", "get_parent", > + (char *) &snapid, sizeof (snapid), > + (char *) reply_buf, size, > + CEPH_OSD_FLAG_READ, NULL); > + dout("%s: rbd_req_sync_exec returned %d\n", __func__, ret); > + if (ret < 0) > + goto out_err; > + > + ret = -ERANGE; > + p = reply_buf; > + end = (char *) reply_buf + size; > + ceph_decode_64_safe(&p, end, parent_spec->pool_id, out_err); > + if (parent_spec->pool_id == CEPH_NOPOOL) > + goto out; /* No parent? No problem. */ > + > + image_id = ceph_extract_encoded_string(&p, end, &len, GFP_KERNEL); > + if (IS_ERR(image_id)) { > + ret = PTR_ERR(image_id); > + goto out_err; > + } > + parent_spec->image_id = image_id; > + ceph_decode_64_safe(&p, end, parent_spec->snap_id, out_err); > + ceph_decode_64_safe(&p, end, overlap, out_err); > + > + rbd_dev->parent_overlap = overlap; > + rbd_dev->parent_spec = parent_spec; > + parent_spec = NULL; /* rbd_dev now owns this */ > +out: > + ret = 0; > +out_err: > + kfree(reply_buf); > + rbd_spec_put(parent_spec); > + > + return ret; > +} > + > static int rbd_dev_v2_snap_context(struct rbd_device *rbd_dev, u64 *ver) > { > size_t size; > @@ -3154,6 +3268,12 @@ static int rbd_dev_v1_probe(struct rbd_device > *rbd_dev) > ret = rbd_read_header(rbd_dev, &rbd_dev->header); > if (ret < 0) > goto out_err; > + > + /* Version 1 images have no parent (no layering) */ > + > + rbd_dev->parent_spec = NULL; > + rbd_dev->parent_overlap = 0; > + > rbd_dev->image_format = 1; > > dout("discovered version 1 image, header name is %s\n", > @@ -3205,6 +3325,14 @@ static int rbd_dev_v2_probe(struct rbd_device > *rbd_dev) > if (ret < 0) > goto out_err; > > + /* If the image supports layering, get the parent info */ > + > + if (rbd_dev->header.features & RBD_FEATURE_LAYERING) { > + ret = rbd_dev_v2_parent_info(rbd_dev); > + if (ret < 0) > + goto out_err; > + } > + > /* crypto and compression type aren't (yet) supported for v2 images */ > > rbd_dev->header.crypt_type = 0; > @@ -3224,6 +3352,9 @@ static int rbd_dev_v2_probe(struct rbd_device > *rbd_dev) > > return 0; > out_err: > + rbd_dev->parent_overlap = 0; > + rbd_spec_put(rbd_dev->parent_spec); > + rbd_dev->parent_spec = NULL; > kfree(rbd_dev->header_name); > rbd_dev->header_name = NULL; > kfree(rbd_dev->header.object_prefix); > diff --git a/include/linux/ceph/rados.h b/include/linux/ceph/rados.h > index 0a99099..15077db 100644 > --- a/include/linux/ceph/rados.h > +++ b/include/linux/ceph/rados.h > @@ -87,6 +87,8 @@ struct ceph_pg { > * > * lpgp_num -- as above. > */ > +#define CEPH_NOPOOL ((__u64) (-1)) /* pool id not defined */ > + > #define CEPH_PG_TYPE_REP 1 > #define CEPH_PG_TYPE_RAID4 2 > #define CEPH_PG_POOL_VERSION 2 >