forked from luck/tmp_suning_uos_patched
rbd: get the snapshot context for a v2 image
Fetch the snapshot context for an rbd format 2 image by calling the "get_snapcontext" method on its header object. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
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b1b5402aa9
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35d489f946
@ -62,6 +62,7 @@
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#define RBD_MINORS_PER_MAJOR 256 /* max minors per blkdev */
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#define RBD_MAX_SNAP_NAME_LEN 32
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#define RBD_MAX_SNAP_COUNT 510 /* allows max snapc to fit in 4KB */
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#define RBD_MAX_OPT_LEN 1024
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#define RBD_SNAP_HEAD_NAME "-"
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@ -2240,6 +2241,84 @@ static int rbd_dev_v2_features(struct rbd_device *rbd_dev)
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&rbd_dev->header.features);
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}
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static int rbd_dev_v2_snap_context(struct rbd_device *rbd_dev)
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{
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size_t size;
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int ret;
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void *reply_buf;
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void *p;
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void *end;
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u64 seq;
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u32 snap_count;
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struct ceph_snap_context *snapc;
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u32 i;
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/*
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* We'll need room for the seq value (maximum snapshot id),
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* snapshot count, and array of that many snapshot ids.
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* For now we have a fixed upper limit on the number we're
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* prepared to receive.
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*/
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size = sizeof (__le64) + sizeof (__le32) +
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RBD_MAX_SNAP_COUNT * sizeof (__le64);
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reply_buf = kzalloc(size, GFP_KERNEL);
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if (!reply_buf)
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return -ENOMEM;
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ret = rbd_req_sync_exec(rbd_dev, rbd_dev->header_name,
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"rbd", "get_snapcontext",
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NULL, 0,
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reply_buf, size,
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CEPH_OSD_FLAG_READ, NULL);
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dout("%s: rbd_req_sync_exec returned %d\n", __func__, ret);
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if (ret < 0)
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goto out;
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ret = -ERANGE;
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p = reply_buf;
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end = (char *) reply_buf + size;
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ceph_decode_64_safe(&p, end, seq, out);
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ceph_decode_32_safe(&p, end, snap_count, out);
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/*
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* Make sure the reported number of snapshot ids wouldn't go
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* beyond the end of our buffer. But before checking that,
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* make sure the computed size of the snapshot context we
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* allocate is representable in a size_t.
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*/
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if (snap_count > (SIZE_MAX - sizeof (struct ceph_snap_context))
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/ sizeof (u64)) {
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ret = -EINVAL;
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goto out;
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}
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if (!ceph_has_room(&p, end, snap_count * sizeof (__le64)))
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goto out;
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size = sizeof (struct ceph_snap_context) +
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snap_count * sizeof (snapc->snaps[0]);
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snapc = kmalloc(size, GFP_KERNEL);
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if (!snapc) {
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ret = -ENOMEM;
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goto out;
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}
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atomic_set(&snapc->nref, 1);
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snapc->seq = seq;
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snapc->num_snaps = snap_count;
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for (i = 0; i < snap_count; i++)
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snapc->snaps[i] = ceph_decode_64(&p);
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rbd_dev->header.snapc = snapc;
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dout(" snap context seq = %llu, snap_count = %u\n",
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(unsigned long long) seq, (unsigned int) snap_count);
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out:
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kfree(reply_buf);
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return 0;
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}
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/*
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* Scan the rbd device's current snapshot list and compare it to the
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* newly-received snapshot context. Remove any existing snapshots
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@ -2779,6 +2858,12 @@ static int rbd_dev_v2_probe(struct rbd_device *rbd_dev)
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ret = rbd_dev_v2_features(rbd_dev);
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if (ret < 0)
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goto out_err;
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/* Get the snapshot context */
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ret = rbd_dev_v2_snap_context(rbd_dev);
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if (ret)
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goto out_err;
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rbd_dev->image_format = 2;
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dout("discovered version 2 image, header name is %s\n",
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