[Qemu-devel] [PATCH 2/5] blockdev: add discard suboption to -drive

[Paolo Bonzini]

Add support for BDRV_O_UNMAP from the QEMU command-line.

Signed-off-by: Paolo Bonzini <address@hidden>
---
 blockdev.c      | 11 +++++++++++
 qemu-options.hx |  2 ++
 2 files changed, 13 insertions(+)

diff --git a/blockdev.c b/blockdev.c
index 63e6f1e..b4ae36a 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -378,6 +378,13 @@ DriveInfo *drive_init(QemuOpts *opts, BlockInterfaceType 
block_default_type)
        }
     }
 
+    if ((buf = qemu_opt_get(opts, "discard")) != NULL) {
+        if (bdrv_parse_discard_flags(buf, &bdrv_flags) != 0) {
+            error_report("invalid discard option");
+            return NULL;
+        }
+    }
+
     bdrv_flags |= BDRV_O_CACHE_WB;
     if ((buf = qemu_opt_get(opts, "cache")) != NULL) {
         if (bdrv_parse_cache_flags(buf, &bdrv_flags) != 0) {
@@ -1489,6 +1496,10 @@ QemuOptsList qemu_drive_opts = {
             .type = QEMU_OPT_STRING,
             .help = "disk image",
         },{
+            .name = "discard",
+            .type = QEMU_OPT_STRING,
+            .help = "discard operation (ignore/off, unmap/on)",
+        },{
             .name = "cache",
             .type = QEMU_OPT_STRING,
             .help = "host cache usage (none, writeback, writethrough, "
diff --git a/qemu-options.hx b/qemu-options.hx
index 046bdc0..d5a99c7 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -185,6 +185,8 @@ These options have the same definition as they have in 
@option{-hdachs}.
 @var{cache} is "none", "writeback", "unsafe", "directsync" or "writethrough" 
and controls how the host cache is used to access block data.
 @item address@hidden
 @var{aio} is "threads", or "native" and selects between pthread based disk I/O 
and native Linux AIO.
address@hidden address@hidden
address@hidden is one of "ignore" (or "off") or "unmap" (or "on") and controls 
whether @dfn{discard} (also known as @dfn{trim} or @dfn{unmap}) requests are 
ignored or passed to the filesystem.  Some machine types may not support 
discard requests.
 @item address@hidden
 Specify which disk @var{format} will be used rather than detecting
 the format.  Can be used to specifiy format=raw to avoid interpreting
-- 
1.8.1.2