141 src/drives.c
View file
@@ -86,8 +86,7 @@ static struct drive *
create_drive_file (guestfs_h *g, const char *path,
bool readonly, const char *format,
const char *iface, const char *name,
const char *disk_label,
bool use_cache_none)
const char *disk_label, const char *cachemode)
{
struct drive *drv = safe_calloc (g, 1, sizeof *drv);

@@ -99,7 +98,7 @@ create_drive_file (guestfs_h *g, const char *path,
drv->iface = iface ? safe_strdup (g, iface) : NULL;
drv->name = name ? safe_strdup (g, name) : NULL;
drv->disk_label = disk_label ? safe_strdup (g, disk_label) : NULL;
drv->use_cache_none = use_cache_none;
drv->cachemode = cachemode ? safe_strdup (g, cachemode) : NULL;

drv->priv = drv->free_priv = NULL;

@@ -114,8 +113,7 @@ create_drive_non_file (guestfs_h *g,
const char *username, const char *secret,
bool readonly, const char *format,
const char *iface, const char *name,
const char *disk_label,
bool use_cache_none)
const char *disk_label, const char *cachemode)
{
struct drive *drv = safe_calloc (g, 1, sizeof *drv);

@@ -131,7 +129,7 @@ create_drive_non_file (guestfs_h *g,
drv->iface = iface ? safe_strdup (g, iface) : NULL;
drv->name = name ? safe_strdup (g, name) : NULL;
drv->disk_label = disk_label ? safe_strdup (g, disk_label) : NULL;
drv->use_cache_none = use_cache_none;
drv->cachemode = cachemode ? safe_strdup (g, cachemode) : NULL;

drv->priv = drv->free_priv = NULL;

@@ -146,8 +144,7 @@ create_drive_curl (guestfs_h *g,
const char *username, const char *secret,
bool readonly, const char *format,
const char *iface, const char *name,
const char *disk_label,
bool use_cache_none)
const char *disk_label, const char *cachemode)
{
if (secret != NULL) {
error (g, _("curl: you cannot specify a secret with this protocol"));
@@ -179,7 +176,7 @@ create_drive_curl (guestfs_h *g,
servers, nr_servers, exportname,
username, secret,
readonly, format, iface, name, disk_label,
use_cache_none);
cachemode);
}

static struct drive *
@@ -189,8 +186,7 @@ create_drive_gluster (guestfs_h *g,
const char *username, const char *secret,
bool readonly, const char *format,
const char *iface, const char *name,
const char *disk_label,
bool use_cache_none)
const char *disk_label, const char *cachemode)
{
if (username != NULL) {
error (g, _("gluster: you cannot specify a username with this protocol"));
@@ -220,7 +216,7 @@ create_drive_gluster (guestfs_h *g,
servers, nr_servers, exportname,
username, secret,
readonly, format, iface, name, disk_label,
use_cache_none);
cachemode);
}

static int
@@ -242,8 +238,7 @@ create_drive_nbd (guestfs_h *g,
const char *username, const char *secret,
bool readonly, const char *format,
const char *iface, const char *name,
const char *disk_label,
bool use_cache_none)
const char *disk_label, const char *cachemode)
{
if (username != NULL) {
error (g, _("nbd: you cannot specify a username with this protocol"));
@@ -266,7 +261,7 @@ create_drive_nbd (guestfs_h *g,
servers, nr_servers, exportname,
username, secret,
readonly, format, iface, name, disk_label,
use_cache_none);
cachemode);
}

static struct drive *
@@ -276,8 +271,7 @@ create_drive_rbd (guestfs_h *g,
const char *username, const char *secret,
bool readonly, const char *format,
const char *iface, const char *name,
const char *disk_label,
bool use_cache_none)
const char *disk_label, const char *cachemode)
{
size_t i;

@@ -312,7 +306,7 @@ create_drive_rbd (guestfs_h *g,
servers, nr_servers, exportname,
username, secret,
readonly, format, iface, name, disk_label,
use_cache_none);
cachemode);
}

static struct drive *
@@ -322,8 +316,7 @@ create_drive_sheepdog (guestfs_h *g,
const char *username, const char *secret,
bool readonly, const char *format,
const char *iface, const char *name,
const char *disk_label,
bool use_cache_none)
const char *disk_label, const char *cachemode)
{
size_t i;

@@ -362,7 +355,7 @@ create_drive_sheepdog (guestfs_h *g,
servers, nr_servers, exportname,
username, secret,
readonly, format, iface, name, disk_label,
use_cache_none);
cachemode);
}

static struct drive *
@@ -372,8 +365,7 @@ create_drive_ssh (guestfs_h *g,
const char *username, const char *secret,
bool readonly, const char *format,
const char *iface, const char *name,
const char *disk_label,
bool use_cache_none)
const char *disk_label, const char *cachemode)
{
if (secret != NULL) {
error (g, _("ssh: you cannot specify a secret with this protocol"));
@@ -410,7 +402,7 @@ create_drive_ssh (guestfs_h *g,
servers, nr_servers, exportname,
username, secret,
readonly, format, iface, name, disk_label,
use_cache_none);
cachemode);
}

static struct drive *
@@ -420,8 +412,7 @@ create_drive_iscsi (guestfs_h *g,
const char *username, const char *secret,
bool readonly, const char *format,
const char *iface, const char *name,
const char *disk_label,
bool use_cache_none)
const char *disk_label, const char *cachemode)
{
if (username != NULL) {
error (g, _("iscsi: you cannot specify a username with this protocol"));
@@ -458,7 +449,7 @@ create_drive_iscsi (guestfs_h *g,
servers, nr_servers, exportname,
username, secret,
readonly, format, iface, name, disk_label,
use_cache_none);
cachemode);
}

/* Traditionally you have been able to use /dev/null as a filename, as
@@ -537,6 +528,7 @@ free_drive_struct (struct drive *drv)
free (drv->iface);
free (drv->name);
free (drv->disk_label);
free (drv->cachemode);

if (drv->priv && drv->free_priv)
drv->free_priv (drv->priv);
@@ -555,7 +547,7 @@ drive_to_string (guestfs_h *g, const struct drive *drv)
p = guestfs___drive_source_qemu_param (g, &drv->src);

return safe_asprintf
(g, "%s%s%s%s%s%s%s%s%s%s%s",
(g, "%s%s%s%s%s%s%s%s%s%s%s%s",
p,
drv->readonly ? " readonly" : "",
drv->format ? " format=" : "",
@@ -566,7 +558,8 @@ drive_to_string (guestfs_h *g, const struct drive *drv)
drv->name ? : "",
drv->disk_label ? " label=" : "",
drv->disk_label ? : "",
drv->use_cache_none ? " cache=none" : "");
drv->cachemode ? " cache=" : "",
drv->cachemode ? : "");
}

/* Add struct drive to the g->drives vector at the given index. */
@@ -621,47 +614,6 @@ guestfs___free_drives (guestfs_h *g)
g->nr_drives = 0;
}

/* cache=none improves reliability in the event of a host crash.
*
* However this option causes qemu to try to open the file with
* O_DIRECT. This fails on some filesystem types (notably tmpfs).
* So we check if we can open the file with or without O_DIRECT,
* and use cache=none (or not) accordingly.
*
* Notes:
*
* (1) In qemu, cache=none and cache=off are identical.
*
* (2) cache=none does not disable caching entirely. qemu still
* maintains a writeback cache internally, which will be written out
* when qemu is killed (with SIGTERM). It disables *host kernel*
* caching by using O_DIRECT. To disable caching entirely in kernel
* and qemu we would need to use cache=directsync but there is a
* performance penalty for that.
*
* (3) This function is only called on the !readonly path. We must
* try to open with O_RDWR to test that the file is readable and
* writable here.
*/
static int
test_cache_none (guestfs_h *g, const char *filename)
{
int fd = open (filename, O_RDWR|O_DIRECT);
if (fd >= 0) {
close (fd);
return 1;
}

fd = open (filename, O_RDWR);
if (fd >= 0) {
close (fd);
return 0;
}

perrorf (g, "%s", filename);
return -1;
}

/* Check string parameter matches ^[-_[:alnum:]]+$ (in C locale). */
static int
valid_format_iface (const char *str)
@@ -827,7 +779,7 @@ guestfs__add_drive_opts (guestfs_h *g, const char *filename,
struct drive_server *servers = NULL;
const char *username;
const char *secret;
int use_cache_none;
const char *cachemode;
struct drive *drv;
size_t i, drv_index;

@@ -853,6 +805,8 @@ guestfs__add_drive_opts (guestfs_h *g, const char *filename,
? optargs->username : NULL;
secret = optargs->bitmask & GUESTFS_ADD_DRIVE_OPTS_SECRET_BITMASK
? optargs->secret : NULL;
cachemode = optargs->bitmask & GUESTFS_ADD_DRIVE_OPTS_CACHEMODE_BITMASK
? optargs->cachemode : NULL;

if (format && !valid_format_iface (format)) {
error (g, _("%s parameter is empty or contains disallowed characters"),
@@ -871,6 +825,12 @@ guestfs__add_drive_opts (guestfs_h *g, const char *filename,
free_drive_servers (servers, nr_servers);
return -1;
}
if (cachemode &&
!(STREQ (cachemode, "writeback") || STREQ (cachemode, "unsafe"))) {
error (g, _("cachemode parameter must be 'writeback' (default) or 'unsafe'"));
free_drive_servers (servers, nr_servers);
return -1;
}

if (STREQ (protocol, "file")) {
if (servers != NULL) {
@@ -893,95 +853,88 @@ guestfs__add_drive_opts (guestfs_h *g, const char *filename,
drv = create_drive_dev_null (g, readonly, format, iface, name,
disk_label);
else {
/* For writable files, see if we can use cache=none. This also
* checks for the existence of the file. For readonly we have
* to do the check explicitly.
/* We have to check for the existence of the file since that's
* required by the API.
*/
use_cache_none = readonly ? false : test_cache_none (g, filename);
if (use_cache_none == -1)
if (access (filename, R_OK) == -1) {
perrorf (g, "%s", filename);
return -1;

if (readonly) {
if (access (filename, R_OK) == -1) {
perrorf (g, "%s", filename);
return -1;
}
}

drv = create_drive_file (g, filename, readonly, format, iface, name,
disk_label, use_cache_none);
disk_label, cachemode);
}
}
else if (STREQ (protocol, "ftp")) {
drv = create_drive_curl (g, drive_protocol_ftp,
servers, nr_servers, filename,
username, secret,
readonly, format, iface, name,
disk_label, false);
disk_label, cachemode);
}
else if (STREQ (protocol, "ftps")) {
drv = create_drive_curl (g, drive_protocol_ftps,
servers, nr_servers, filename,
username, secret,
readonly, format, iface, name,
disk_label, false);
disk_label, cachemode);
}
else if (STREQ (protocol, "gluster")) {
drv = create_drive_gluster (g, servers, nr_servers, filename,
username, secret,
readonly, format, iface, name,
disk_label, false);
disk_label, cachemode);
}
else if (STREQ (protocol, "http")) {
drv = create_drive_curl (g, drive_protocol_http,
servers, nr_servers, filename,
username, secret,
readonly, format, iface, name,
disk_label, false);
disk_label, cachemode);
}
else if (STREQ (protocol, "https")) {
drv = create_drive_curl (g, drive_protocol_https,
servers, nr_servers, filename,
username, secret,
readonly, format, iface, name,
disk_label, false);
disk_label, cachemode);
}
else if (STREQ (protocol, "iscsi")) {
drv = create_drive_iscsi (g, servers, nr_servers, filename,
username, secret,
readonly, format, iface, name,
disk_label, false);
disk_label, cachemode);
}
else if (STREQ (protocol, "nbd")) {
drv = create_drive_nbd (g, servers, nr_servers, filename,
username, secret,
readonly, format, iface, name,
disk_label, false);
disk_label, cachemode);
}
else if (STREQ (protocol, "rbd")) {
drv = create_drive_rbd (g, servers, nr_servers, filename,
username, secret,
readonly, format, iface, name,
disk_label, false);
disk_label, cachemode);
}
else if (STREQ (protocol, "sheepdog")) {
drv = create_drive_sheepdog (g, servers, nr_servers, filename,
username, secret,
readonly, format, iface, name,
disk_label, false);
disk_label, cachemode);
}
else if (STREQ (protocol, "ssh")) {
drv = create_drive_ssh (g, servers, nr_servers, filename,
username, secret,
readonly, format, iface, name,
disk_label, false);
disk_label, cachemode);
}
else if (STREQ (protocol, "tftp")) {
drv = create_drive_curl (g, drive_protocol_tftp,
servers, nr_servers, filename,
username, secret,
readonly, format, iface, name,
disk_label, false);
disk_label, cachemode);
}
else {
error (g, _("unknown protocol '%s'"), protocol);
2 src/guestfs-internal.h
View file
@@ -172,7 +172,7 @@ struct drive {
char *iface;
char *name;
char *disk_label;
bool use_cache_none;
char *cachemode;

/* Data used by the backend. */
void *priv;
4 src/launch-direct.c
View file
@@ -996,10 +996,10 @@ qemu_drive_param (guestfs_h *g, struct backend_direct_data *data,
iface = "virtio";

return safe_asprintf
(g, "file=%s%s%s%s%s%s%s,id=hd%zu,if=%s",
(g, "file=%s%s,cache=%s%s%s%s%s,id=hd%zu,if=%s",
escaped_file,
drv->readonly ? ",snapshot=on" : "",
drv->use_cache_none ? ",cache=none" : "",
drv->cachemode ? drv->cachemode : "writeback",
drv->format ? ",format=" : "",
drv->format ? drv->format : "",
drv->disk_label ? ",serial=" : "",
11 src/launch-libvirt.c
View file
@@ -1236,11 +1236,12 @@ construct_libvirt_xml_disk (guestfs_h *g,
return -1;
}

if (drv->use_cache_none) {
XMLERROR (-1,
xmlTextWriterWriteAttribute (xo, BAD_CAST "cache",
BAD_CAST "none"));
}
XMLERROR (-1,
xmlTextWriterWriteAttribute (xo, BAD_CAST "cache",
BAD_CAST (drv->cachemode ?
drv->cachemode :
"writeback")));

XMLERROR (-1, xmlTextWriterEndElement (xo));

if (drv->disk_label) {