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Add support for ioctl's DM_UEVENT_GENERATED_FLAG.

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We need to know whether we should wait for any uevent or not when
using udev_sync. A kernel patch was posted recently that changed the
way uevents are sent on dm device resume - it is sent only if the
device has been suspended before. There's also a new DM_UEVENT_GENERATED_FLAG
in the ioctl to notify userspace whether the event was generated.

If the uevent was not generated (e.g. the situation where the device is
*not* suspended and we call a resume), we just call dm_udev_complete
explicitly from within libdevmapper itself to prevent infinite waiting
while trying to synchronise with udev processing.
This commit is contained in:
Peter Rajnoha 2010-03-23 14:38:37 +00:00
parent 7eaf1f294d
commit 14ad41a065
3 changed files with 34 additions and 12 deletions
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1
WHATS_NEW_DM
View File

@ -1,5 +1,6 @@
Version 1.02.46 -
================================
Add support for ioctl's DM_UEVENT_GENERATED_FLAG.
Version 1.02.45 - 9th March 2010
================================

36
libdm/ioctl/libdm-iface.c
View File

@ -1505,18 +1505,28 @@ static int _mknodes_v4(struct dm_task *dmt)
*/
static int _udev_complete(struct dm_task *dmt)
{
uint32_t cookie;
uint16_t base;
if (dmt->cookie_set) {
if (dmt->cookie_set &&
(base = dmt->event_nr & ~DM_UDEV_FLAGS_MASK))
/* strip flags from the cookie and use cookie magic instead */
cookie = (dmt->event_nr & ~DM_UDEV_FLAGS_MASK) |
(DM_COOKIE_MAGIC << DM_UDEV_FLAGS_SHIFT);
return dm_udev_complete(cookie);
}
return dm_udev_complete(base | (DM_COOKIE_MAGIC <<
DM_UDEV_FLAGS_SHIFT));
return 1;
}
static int _check_uevent_generated(struct dm_ioctl *dmi)
{
if (!dm_check_version() ||
_dm_version < 4 ||
_dm_version_minor < 17)
/* can't check, assume uevent is generated */
return 1;
return dmi->flags & DM_UEVENT_GENERATED_FLAG;
}
static int _create_and_load_v4(struct dm_task *dmt)
{
struct dm_task *task;
@ -1691,6 +1701,7 @@ static struct dm_ioctl *_do_dm_ioctl(struct dm_task *dmt, unsigned command,
unsigned repeat_count)
{
struct dm_ioctl *dmi;
int ioctl_with_uevent;
dmi = _flatten(dmt, repeat_count);
if (!dmi) {
@ -1706,6 +1717,10 @@ static struct dm_ioctl *_do_dm_ioctl(struct dm_task *dmt, unsigned command,
if (dmt->no_open_count)
dmi->flags |= DM_SKIP_BDGET_FLAG;
ioctl_with_uevent = dmt->type == DM_DEVICE_RESUME ||
dmt->type == DM_DEVICE_REMOVE ||
dmt->type == DM_DEVICE_RENAME;
/*
* Prevent udev vs. libdevmapper race when processing nodes and
* symlinks. This can happen when the udev rules are installed and
@ -1715,10 +1730,7 @@ static struct dm_ioctl *_do_dm_ioctl(struct dm_task *dmt, unsigned command,
* to be applied at all in this situation so we can gracefully fallback
* to libdevmapper's node and symlink creation code.
*/
if (dm_udev_get_sync_support() && !dmt->cookie_set &&
(dmt->type == DM_DEVICE_RESUME ||
dmt->type == DM_DEVICE_REMOVE ||
dmt->type == DM_DEVICE_RENAME)) {
if (dm_udev_get_sync_support() && !dmt->cookie_set && ioctl_with_uevent) {
log_debug("Cookie value is not set while trying to call "
"DM_DEVICE_RESUME, DM_DEVICE_REMOVE or DM_DEVICE_RENAME "
"ioctl. Please, consider using libdevmapper's udev "
@ -1774,6 +1786,10 @@ static struct dm_ioctl *_do_dm_ioctl(struct dm_task *dmt, unsigned command,
return NULL;
}
}
if (ioctl_with_uevent && !_check_uevent_generated(dmi))
_udev_complete(dmt);
#else /* Userspace alternative for testing */
#endif
return dmi;

9
libdm/misc/dm-ioctl.h
View File

@ -268,9 +268,9 @@ enum {
#define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
#define DM_VERSION_MAJOR 4
#define DM_VERSION_MINOR 16
#define DM_VERSION_MINOR 17
#define DM_VERSION_PATCHLEVEL 0
#define DM_VERSION_EXTRA "-ioctl (2009-11-05)"
#define DM_VERSION_EXTRA "-ioctl (2010-03-05)"
/* Status bits */
#define DM_READONLY_FLAG (1 << 0) /* In/Out */
@ -318,4 +318,9 @@ enum {
*/
#define DM_QUERY_INACTIVE_TABLE_FLAG (1 << 12) /* In */
/*
* If set, a uevent was generated for which the caller may need to wait.
*/
#define DM_UEVENT_GENERATED_FLAG (1 << 13) /* Out */
#endif /* _LINUX_DM_IOCTL_H */