qemu-ga: add guest-fstrim command
FITRIM is a mounted filesystem feature to discard (or "trim") blocks which
are not in use by the filesystem. This is useful for solid-state drives
(SSDs) and thinly-provisioned storage. Provide access to the feature
from the host so that filesystems can be trimmed periodically or before
migration.
Here is an example using scsi_debug:
# modprobe scsi_debug lbpu=1 lbpws=1
# sg_vpd -p0xb2 /dev/sdb
Logical block provisioning VPD page (SBC):
Unmap command supported (LBPU): 1
Write same (16) with unmap bit supported (LBWS): 1
Write same (10) with unmap bit supported (LBWS10): 0
# mke2fs /dev/sdb
# cat /sys/bus/pseudo/drivers/scsi_debug/map
1-616,16257-16383
# mount /dev/sdb /run/media/pbonzini/test
# dd if=/dev/zero of=/run/media/pbonzini/test/file
# cat map
1-616,645-1588,1599-4026,4029-16383
# rm /run/media/pbonzini/test/file
# ./qemu-ga /dev/fd/0
{"execute":"guest-fstrim"}
{"return": {}}
# cat map
1-612
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
diff --git a/qga/commands-win32.c b/qga/commands-win32.c
index eb8d140..54bc546 100644
--- a/qga/commands-win32.c
+++ b/qga/commands-win32.c
@@ -173,6 +173,17 @@
return 0;
}
+/*
+ * Walk list of mounted file systems in the guest, and discard unused
+ * areas.
+ */
+void qmp_guest_fstrim(bool has_minimum, int64_t minimum, Error **err)
+{
+ error_set(err, QERR_UNSUPPORTED);
+
+ return;
+}
+
typedef enum {
GUEST_SUSPEND_MODE_DISK,
GUEST_SUSPEND_MODE_RAM
