Send notifications when we change the rbd header (e.g. create a snapshot)
and wait for such notifications.  This allows synchronizing the snapshot
creation between different rbd clients/rools.
Signed-off-by: NYehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: NSage Weil <sage@newdream.net>

Previously we didn't clean up the sysfs entry that was just
created.
Signed-off-by: NYehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: NSage Weil <sage@newdream.net>

The new interface creates directories per mapped image
and under each it creates a subdir per available snapshot.
This allows keeping a cleaner interface within the sysfs
guidelines. The ABI documentation was updated too.
Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NYehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: NSage Weil <sage@newdream.net>

We should be passing "buf" here insead of "bv".  This is tricky because
it's not the same as kmap() and kunmap().  GCC does warn about it if you
compile on i386 with CONFIG_HIGHMEM.
Signed-off-by: NDan Carpenter <error27@gmail.com>
Signed-off-by: NSage Weil <sage@newdream.net>

ceph_alloc_page_vector() returns ERR_PTR(-ENOMEM) on errors.
Signed-off-by: NDan Carpenter <error27@gmail.com>
Signed-off-by: NSage Weil <sage@newdream.net>

rbd_get_segment() can't return a negative value, we don't need to check
the return output.
Signed-off-by: NYehuda Sadeh <yehuda@hq.newdream.net>

rbd_client_create() doesn't free rbdc, this leads to many leaks.

seg_len in rbd_do_op() is unsigned, so (seg_len < 0) makes no sense.
Also if fixed check fails then seg_name is leaked.
Signed-off-by: NVasiliy Kulikov <segooon@gmail.com>
Signed-off-by: NYehuda Sadeh <yehuda@hq.newdream.net>

The rados block device (rbd), based on osdblk, creates a block device
that is backed by objects stored in the Ceph distributed object storage
cluster.  Each device consists of a single metadata object and data
striped over many data objects.

The rbd driver supports read-only snapshots.
Signed-off-by: NYehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: NSage Weil <sage@newdream.net>