Describe new metadata namespace: "qemu". Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> --- docs/interop/nbd.txt | 37 +++++++++++++++++++++++++++++++++++++ MAINTAINERS | 1 + 2 files changed, 38 insertions(+) create mode 100644 docs/interop/nbd.txt
diff --git a/docs/interop/nbd.txt b/docs/interop/nbd.txt new file mode 100644 index 0000000000..7366269fc0 --- /dev/null +++ b/docs/interop/nbd.txt @@ -0,0 +1,37 @@ +Qemu supports NBD protocol, and has internal NBD client (look at +block/nbd.c), internal NBD server (look at blockdev-nbd.c) as well as +external NBD server tool - qemu-nbd.c. The common code is placed in +nbd/*. + +NBD protocol is specified here: +https://github.com/NetworkBlockDevice/nbd/blob/master/doc/proto.md + +This following paragraphs describe some specific properties of NBD +protocol realization in Qemu. + + += Metadata namespaces = + +Qemu supports "base:allocation" metadata context as defined in the NBD +protocol specification and defines own metadata namespace: "qemu". + + +== "qemu" namespace == + +For now, the only type of metadata context in the namespace is dirty +bitmap. All available metadata contexts have the following form: + + qemu:dirty-bitmap:<dirty-bitmap-export-name> + +Each dirty-bitmap metadata context defines the only one flag for +extents in reply for NBD_CMD_BLOCK_STATUS: + + bit 0: NBD_STATE_DIRTY, means that the extent is "dirty" + +For NBD_OPT_LIST_META_CONTEXT the following queries are supported +additionally to "qemu:dirty-bitmap:<dirty-bitmap-export-name>": + +* "qemu:" : returns list of all available metadata contexts in the + namespace. +* "qemu:dirty-bitmap:" : returns list of all available dirty-bitmap + metadata contexts. diff --git a/MAINTAINERS b/MAINTAINERS index e187b1f18f..887b479440 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -1923,6 +1923,7 @@ F: nbd/ F: include/block/nbd* F: qemu-nbd.* F: blockdev-nbd.c +F: docs/interop/nbd.txt T: git git://repo.or.cz/qemu/ericb.git nbd NFS -- 2.11.1