[Qemu-devel] [PATCH V2 3/4] qemu-nbd: add doc for internal snapshot export

[Wenchao Xia <xiawenc@linux.vnet.ibm.com>]

Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
---
 qemu-nbd.c    |    8 +++++++-
 qemu-nbd.texi |    8 +++++++-
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/qemu-nbd.c b/qemu-nbd.c
index e450d04..8cb4bf1 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -80,7 +80,13 @@ static void usage(const char *name)
 "\n"
 "Block device options:\n"
 "  -r, --read-only      export read-only\n"
-"  -s, --snapshot       use snapshot file\n"
+"  -s, --snapshot       use FILE as an external snapshot, create a temporary\n"
+"                       file with backing_file=FILE, redirect the write to\n"
+"                       the temporary one\n"
+"  -l, --snapshot-load=PARAM\n"
+"                       load an internal snapshot inside FILE and export it\n"
+"                       as an read-only device, PARAM format is\n"
+"                       'id=[ID],name=[NAME]'\n"
 "  -n, --nocache        disable host cache\n"
 "      --cache=MODE     set cache mode (none, writeback, ...)\n"
 #ifdef CONFIG_LINUX_AIO
diff --git a/qemu-nbd.texi b/qemu-nbd.texi
index 6055ec6..69e9e9a 100644
--- a/qemu-nbd.texi
+++ b/qemu-nbd.texi
@@ -27,7 +27,13 @@ Export QEMU disk image using NBD protocol.
 @item -P, --partition=@var{num}
   only expose partition @var{num}
 @item -s, --snapshot
-  use snapshot file
+  use @var{filename} as an external snapshot, create a temporary
+  file with backing_file=@var{filename}, redirect the write to
+  the temporary one
+@item -l, --snapshot-load=@var{param}
+  load an internal snapshot inside @var{filename} and export it
+  as an read-only device, @var{param} format is
+  'id=[ID],name=[NAME]'
 @item -n, --nocache
 @itemx --cache=@var{cache}
   set cache mode to be used with the file.  See the documentation of
-- 
1.7.1