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authorIlya Dryomov <ilya.dryomov@inktank.com>2014-07-24 10:42:13 +0400
committerIlya Dryomov <ilya.dryomov@inktank.com>2014-07-25 13:16:50 +0400
commit4d9b67cddd9b9bc320473a334cc8023a4186092f (patch)
tree016babd2335843eafb456b801eec4fdb70bd9a1b /drivers/block
parente8f59b595d05b7251a9a3054c14567fd8c8220ef (diff)
rbd: take snap_id into account when reading in parent info
If we are mapping a snapshot, we must read in the parent_overlap value of that snapshot instead of that of the base image. Not doing so may in particular result in us returning zeros instead of user data: # cat overlap-snap.sh #!/bin/bash rbd create --size 10 --image-format 2 foo FOO_DEV=$(rbd map foo) dd if=/dev/urandom of=$FOO_DEV bs=1M &>/dev/null echo "Base image" dd if=$FOO_DEV bs=1 count=16 skip=$(((4 << 20) - 8)) 2>/dev/null | xxd rbd snap create foo@snap rbd snap protect foo@snap rbd clone foo@snap bar rbd snap create bar@snap BAR_DEV=$(rbd map bar@snap) echo "Snapshot" dd if=$BAR_DEV bs=1 count=16 skip=$(((4 << 20) - 8)) 2>/dev/null | xxd rbd resize --allow-shrink --size 4 bar echo "Snapshot after base image resize" dd if=$BAR_DEV bs=1 count=16 skip=$(((4 << 20) - 8)) 2>/dev/null | xxd # ./overlap-snap.sh Base image 0000000: e781 e33b d34b 2225 6034 2845 a2e3 36ed ...;.K"%`4(E..6. Snapshot 0000000: e781 e33b d34b 2225 6034 2845 a2e3 36ed ...;.K"%`4(E..6. Resizing image: 100% complete...done. Snapshot after base image resize 0000000: e781 e33b d34b 2225 0000 0000 0000 0000 ...;.K"%........ Even though bar@snap is taken with the old bar parent_overlap (8M), reads from bar@snap beyond the new bar parent_overlap (4M) return zeroes. Fix it. Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com> Reviewed-by: Alex Elder <elder@linaro.org>
Diffstat (limited to 'drivers/block')
-rw-r--r--drivers/block/rbd.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index c4606987e9d..cbc89fa9a67 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -4020,7 +4020,7 @@ static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev)
goto out_err;
}
- snapid = cpu_to_le64(CEPH_NOSNAP);
+ snapid = cpu_to_le64(rbd_dev->spec->snap_id);
ret = rbd_obj_method_sync(rbd_dev, rbd_dev->header_name,
"rbd", "get_parent",
&snapid, sizeof (snapid),