[libvirt] [PATCH 10/11] Rewrite qemu-img backing store format handling
Daniel P. Berrange
berrange at redhat.com
Mon Jul 12 13:30:47 UTC 2010
When creating qcow2 files with a backing store, it is important
to set an explicit format to prevent QEMU probing. The storage
backend was only doing this if it found a 'kvm-img' binary. This
is wrong because plenty of kvm-img binaries don't support an
explicit format, and plenty of 'qemu-img' binaries do support
a format. The result was that most qcow2 files were not getting
a backing store format.
This patch runs 'qemu-img -h' to check for the two support
argument formats
'-o backing_format=raw'
'-F raw'
and use whichever option it finds
* src/storage/storage_backend.c: Query binary to determine
how to set the backing store format
---
src/storage/storage_backend.c | 214 +++++++++++++++++++++++++++++------------
1 files changed, 152 insertions(+), 62 deletions(-)
diff --git a/src/storage/storage_backend.c b/src/storage/storage_backend.c
index aba8937..c185693 100644
--- a/src/storage/storage_backend.c
+++ b/src/storage/storage_backend.c
@@ -561,6 +561,69 @@ static int virStorageBackendCreateExecCommand(virStoragePoolObjPtr pool,
return 0;
}
+enum {
+ QEMU_IMG_BACKING_FORMAT_NONE = 0,
+ QEMU_IMG_BACKING_FORMAT_FLAG,
+ QEMU_IMG_BACKING_FORMAT_OPTIONS,
+};
+
+static int virStorageBackendQEMUImgBackingFormat(const char *qemuimg)
+{
+ const char *const qemuarg[] = { qemuimg, "-h", NULL };
+ const char *const qemuenv[] = { "LC_ALL=C", NULL };
+ pid_t child = 0;
+ int status;
+ int newstdout = -1;
+ char *help = NULL;
+ enum { MAX_HELP_OUTPUT_SIZE = 1024*8 };
+ int len;
+ char *start;
+ char *end;
+ char *tmp;
+ int ret = -1;
+
+ if (virExec(qemuarg, qemuenv, NULL,
+ &child, -1, &newstdout, NULL, VIR_EXEC_CLEAR_CAPS) < 0)
+ goto cleanup;
+
+ if ((len = virFileReadLimFD(newstdout, MAX_HELP_OUTPUT_SIZE, &help)) < 0) {
+ virReportSystemError(errno,
+ _("Unable to read '%s -h' output"),
+ qemuimg);
+ goto cleanup;
+ }
+
+ start = strstr(help, " create ");
+ end = strstr(start, "\n");
+ if ((tmp = strstr(start, "-F fmt")) && tmp < end)
+ ret = QEMU_IMG_BACKING_FORMAT_FLAG;
+ else if ((tmp = strstr(start, "[-o options]")) && tmp < end)
+ ret = QEMU_IMG_BACKING_FORMAT_OPTIONS;
+ else
+ ret = QEMU_IMG_BACKING_FORMAT_NONE;
+
+cleanup:
+ VIR_FREE(help);
+ close(newstdout);
+rewait:
+ if (child) {
+ if (waitpid(child, &status, 0) != child) {
+ if (errno == EINTR)
+ goto rewait;
+
+ VIR_ERROR(_("Unexpected exit status from qemu %d pid %lu"),
+ WEXITSTATUS(status), (unsigned long)child);
+ }
+ if (WEXITSTATUS(status) != 0) {
+ VIR_WARN("Unexpected exit status '%d', qemu probably failed",
+ WEXITSTATUS(status));
+ }
+ }
+
+ return ret;
+}
+
+
static int
virStorageBackendCreateQemuImg(virConnectPtr conn,
virStoragePoolObjPtr pool,
@@ -568,10 +631,9 @@ virStorageBackendCreateQemuImg(virConnectPtr conn,
virStorageVolDefPtr inputvol,
unsigned int flags ATTRIBUTE_UNUSED)
{
- int ret;
+ int ret = -1;
char size[100];
char *create_tool;
- short use_kvmimg;
const char *type = virStorageFileFormatTypeToString(vol->target.format);
const char *backingType = vol->backingStore.path ?
@@ -582,41 +644,10 @@ virStorageBackendCreateQemuImg(virConnectPtr conn,
const char *inputPath = inputvol ? inputvol->target.path : NULL;
/* Treat input block devices as 'raw' format */
const char *inputType = inputPath ?
- virStorageFileFormatTypeToString(inputvol->type == VIR_STORAGE_VOL_BLOCK ? VIR_STORAGE_FILE_RAW : inputvol->target.format) :
- NULL;
-
- const char **imgargv;
- /* The extra NULL field is for indicating encryption (-e). */
- const char *imgargvnormal[] = {
- NULL, "create",
- "-f", type,
- vol->target.path,
- size,
- NULL,
- NULL
- };
- /* Extra NULL fields are for including "backingType" when using
- * kvm-img (-F backingType), and for indicating encryption (-e).
- */
- const char *imgargvbacking[] = {
- NULL, "create",
- "-f", type,
- "-b", vol->backingStore.path,
- vol->target.path,
- size,
- NULL,
- NULL,
- NULL,
- NULL
- };
- const char *convargv[] = {
- NULL, "convert",
- "-f", inputType,
- "-O", type,
- inputPath,
- vol->target.path,
- NULL,
- };
+ virStorageFileFormatTypeToString(inputvol->type == VIR_STORAGE_VOL_BLOCK ?
+ VIR_STORAGE_FILE_RAW :
+ inputvol->target.format) :
+ NULL;
if (type == NULL) {
virStorageReportError(VIR_ERR_INTERNAL_ERROR,
@@ -690,44 +721,103 @@ virStorageBackendCreateQemuImg(virConnectPtr conn,
}
}
- if ((create_tool = virFindFileInPath("kvm-img")) != NULL)
- use_kvmimg = 1;
- else if ((create_tool = virFindFileInPath("qemu-img")) != NULL)
- use_kvmimg = 0;
- else {
+ /* Size in KB */
+ snprintf(size, sizeof(size), "%lluK", vol->capacity/1024);
+
+ /* KVM is usually ahead of qemu on features, so try that first */
+ create_tool = virFindFileInPath("kvm-img");
+ if (!create_tool)
+ create_tool = virFindFileInPath("qemu-img");
+
+ if (!create_tool) {
virStorageReportError(VIR_ERR_INTERNAL_ERROR,
"%s", _("unable to find kvm-img or qemu-img"));
return -1;
}
if (inputvol) {
- convargv[0] = create_tool;
- imgargv = convargv;
+ const char *imgargv[] = {
+ create_tool,
+ "convert",
+ "-f", inputType,
+ "-O", type,
+ inputPath,
+ vol->target.path,
+ NULL,
+ };
+
+ ret = virStorageBackendCreateExecCommand(pool, vol, imgargv);
} else if (vol->backingStore.path) {
- imgargvbacking[0] = create_tool;
- if (use_kvmimg) {
- imgargvbacking[6] = "-F";
- imgargvbacking[7] = backingType;
- imgargvbacking[8] = vol->target.path;
- imgargvbacking[9] = size;
+ const char *imgargv[] = {
+ create_tool,
+ "create",
+ "-f", type,
+ "-b", vol->backingStore.path,
+ NULL,
+ NULL,
+ NULL,
+ NULL,
+ NULL,
+ NULL
+ };
+ int imgformat = virStorageBackendQEMUImgBackingFormat(create_tool);
+ char *optflag = NULL;
+ if (imgformat < 0)
+ goto cleanup;
+
+ switch (imgformat) {
+ case QEMU_IMG_BACKING_FORMAT_FLAG:
+ imgargv[6] = "-F";
+ imgargv[7] = backingType;
+ imgargv[8] = vol->target.path;
+ imgargv[9] = size;
+ if (vol->target.encryption != NULL)
+ imgargv[10] = "-e";
+ break;
+
+ case QEMU_IMG_BACKING_FORMAT_OPTIONS:
+ if (virAsprintf(&optflag, "backing_fmt=%s", backingType) < 0) {
+ virReportOOMError();
+ goto cleanup;
+ }
+ imgargv[6] = "-o";
+ imgargv[7] = optflag;
+ imgargv[8] = vol->target.path;
+ imgargv[9] = size;
if (vol->target.encryption != NULL)
- imgargvbacking[10] = "-e";
- } else if (vol->target.encryption != NULL)
- imgargvbacking[8] = "-e";
- imgargv = imgargvbacking;
+ imgargv[10] = "-e";
+ break;
+
+ default:
+ VIR_INFO("Unable to set backing store format for %s with %s",
+ vol->target.path, create_tool);
+ imgargv[6] = vol->target.path;
+ imgargv[7] = size;
+ if (vol->target.encryption != NULL)
+ imgargv[8] = "-e";
+ }
+
+ ret = virStorageBackendCreateExecCommand(pool, vol, imgargv);
+ VIR_FREE(optflag);
} else {
- imgargvnormal[0] = create_tool;
- imgargv = imgargvnormal;
+ /* The extra NULL field is for indicating encryption (-e). */
+ const char *imgargv[] = {
+ create_tool,
+ "create",
+ "-f", type,
+ vol->target.path,
+ size,
+ NULL,
+ NULL
+ };
if (vol->target.encryption != NULL)
imgargv[6] = "-e";
- }
+ ret = virStorageBackendCreateExecCommand(pool, vol, imgargv);
+ }
- /* Size in KB */
- snprintf(size, sizeof(size), "%lluK", vol->capacity/1024);
-
- ret = virStorageBackendCreateExecCommand(pool, vol, imgargv);
- VIR_FREE(imgargv[0]);
+ cleanup:
+ VIR_FREE(create_tool);
return ret;
}
--
1.7.1.1
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