diff options
author | Alex Elder <elder@inktank.com> | 2012-07-03 23:01:19 +0200 |
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committer | Alex Elder <elder@inktank.com> | 2012-10-01 21:30:53 +0200 |
commit | 35d489f94651ac19be55661732a7ee15c6304a55 (patch) | |
tree | e6e86b44f650d01eababc6c36a8cd4e02e90d608 /drivers/block/rbd.c | |
parent | rbd: get image features for a v2 image (diff) | |
download | linux-35d489f94651ac19be55661732a7ee15c6304a55.tar.xz linux-35d489f94651ac19be55661732a7ee15c6304a55.zip |
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>
Diffstat (limited to '')
-rw-r--r-- | drivers/block/rbd.c | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index b8b8271bd9e2..b673a8dc161d 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -62,6 +62,7 @@ #define RBD_MINORS_PER_MAJOR 256 /* max minors per blkdev */ #define RBD_MAX_SNAP_NAME_LEN 32 +#define RBD_MAX_SNAP_COUNT 510 /* allows max snapc to fit in 4KB */ #define RBD_MAX_OPT_LEN 1024 #define RBD_SNAP_HEAD_NAME "-" @@ -2240,6 +2241,84 @@ static int rbd_dev_v2_features(struct rbd_device *rbd_dev) &rbd_dev->header.features); } +static int rbd_dev_v2_snap_context(struct rbd_device *rbd_dev) +{ + size_t size; + int ret; + void *reply_buf; + void *p; + void *end; + u64 seq; + u32 snap_count; + struct ceph_snap_context *snapc; + u32 i; + + /* + * We'll need room for the seq value (maximum snapshot id), + * snapshot count, and array of that many snapshot ids. + * For now we have a fixed upper limit on the number we're + * prepared to receive. + */ + size = sizeof (__le64) + sizeof (__le32) + + RBD_MAX_SNAP_COUNT * sizeof (__le64); + reply_buf = kzalloc(size, GFP_KERNEL); + if (!reply_buf) + return -ENOMEM; + + ret = rbd_req_sync_exec(rbd_dev, rbd_dev->header_name, + "rbd", "get_snapcontext", + NULL, 0, + reply_buf, size, + CEPH_OSD_FLAG_READ, NULL); + dout("%s: rbd_req_sync_exec returned %d\n", __func__, ret); + if (ret < 0) + goto out; + + ret = -ERANGE; + p = reply_buf; + end = (char *) reply_buf + size; + ceph_decode_64_safe(&p, end, seq, out); + ceph_decode_32_safe(&p, end, snap_count, out); + + /* + * Make sure the reported number of snapshot ids wouldn't go + * beyond the end of our buffer. But before checking that, + * make sure the computed size of the snapshot context we + * allocate is representable in a size_t. + */ + if (snap_count > (SIZE_MAX - sizeof (struct ceph_snap_context)) + / sizeof (u64)) { + ret = -EINVAL; + goto out; + } + if (!ceph_has_room(&p, end, snap_count * sizeof (__le64))) + goto out; + + size = sizeof (struct ceph_snap_context) + + snap_count * sizeof (snapc->snaps[0]); + snapc = kmalloc(size, GFP_KERNEL); + if (!snapc) { + ret = -ENOMEM; + goto out; + } + + atomic_set(&snapc->nref, 1); + snapc->seq = seq; + snapc->num_snaps = snap_count; + for (i = 0; i < snap_count; i++) + snapc->snaps[i] = ceph_decode_64(&p); + + rbd_dev->header.snapc = snapc; + + dout(" snap context seq = %llu, snap_count = %u\n", + (unsigned long long) seq, (unsigned int) snap_count); + +out: + kfree(reply_buf); + + return 0; +} + /* * Scan the rbd device's current snapshot list and compare it to the * newly-received snapshot context. Remove any existing snapshots @@ -2779,6 +2858,12 @@ static int rbd_dev_v2_probe(struct rbd_device *rbd_dev) ret = rbd_dev_v2_features(rbd_dev); if (ret < 0) goto out_err; + + /* Get the snapshot context */ + + ret = rbd_dev_v2_snap_context(rbd_dev); + if (ret) + goto out_err; rbd_dev->image_format = 2; dout("discovered version 2 image, header name is %s\n", |