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Implement deferred removal of device.

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This can be used in some automated systems and allows device
to be removed after the last user mapping closes it.
This commit is contained in:
Milan Broz
2017-06-23 14:41:54 +02:00
parent a58ed1ada3
commit 32d5e59ab6
12 changed files with 100 additions and 31 deletions
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67
lib/libdevmapper.c
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@@ -72,6 +72,8 @@ static int _dm_task_set_cookie(struct dm_task *dmt, uint32_t *cookie, uint16_t f
static int _dm_udev_wait(uint32_t cookie) { return 0; };
#endif
/* FIXME: We should use DM_UDEV_DISABLE_LIBRARY_FALLBACK */
static int _dm_use_udev(void)
{
#ifdef USE_UDEV /* cannot be enabled if devmapper is too old */
@@ -642,6 +644,41 @@ static char *get_dm_integrity_params(struct crypt_dm_active_device *dmd, uint32_
}
/* DM helpers */
static int _dm_remove(const char *name, int udev_wait, int deferred)
{
int r = 0;
struct dm_task *dmt;
uint32_t cookie = 0;
if (!_dm_use_udev())
udev_wait = 0;
if (!(dmt = dm_task_create(DM_DEVICE_REMOVE)))
return 0;
if (!dm_task_set_name(dmt, name))
goto out;
#if HAVE_DECL_DM_TASK_RETRY_REMOVE
if (!dm_task_retry_remove(dmt))
goto out;
#endif
#if HAVE_DECL_DM_TASK_DEFERRED_REMOVE
if (deferred && !dm_task_deferred_remove(dmt))
goto out;
#endif
if (udev_wait && !_dm_task_set_cookie(dmt, &cookie, 0))
goto out;
r = dm_task_run(dmt);
if (udev_wait)
(void)_dm_udev_wait(cookie);
out:
dm_task_destroy(dmt);
return r;
}
static int _dm_simple(int task, const char *name, int udev_wait)
{
int r = 0;
@@ -657,11 +694,6 @@ static int _dm_simple(int task, const char *name, int udev_wait)
if (name && !dm_task_set_name(dmt, name))
goto out;
#if HAVE_DECL_DM_TASK_RETRY_REMOVE
/* Used only in DM_DEVICE_REMOVE */
if (name && !dm_task_retry_remove(dmt))
goto out;
#endif
if (udev_wait && !_dm_task_set_cookie(dmt, &cookie, 0))
goto out;
@@ -669,7 +701,6 @@ static int _dm_simple(int task, const char *name, int udev_wait)
if (udev_wait)
(void)_dm_udev_wait(cookie);
out:
dm_task_destroy(dmt);
return r;
@@ -710,35 +741,39 @@ error:
return r;
}
int dm_remove_device(struct crypt_device *cd, const char *name,
int force, uint64_t size)
int dm_remove_device(struct crypt_device *cd, const char *name, uint32_t flags)
{
struct crypt_dm_active_device dmd = {};
int r = -EINVAL;
int retries = force ? RETRY_COUNT : 1;
int retries = (flags & CRYPT_DEACTIVATE_FORCE) ? RETRY_COUNT : 1;
int error_target = 0;
if (!name || (force && !size))
if (!name)
return -EINVAL;
if (dm_init_context(cd, DM_UNKNOWN))
return -ENOTSUP;
if (flags & CRYPT_DEACTIVATE_FORCE) {
r = dm_query_device(cd, name, 0, &dmd);
if (!r)
return r;
}
do {
r = _dm_simple(DM_DEVICE_REMOVE, name, 1) ? 0 : -EINVAL;
r = _dm_remove(name, 1, flags & CRYPT_DEACTIVATE_DEFERRED) ? 0 : -EINVAL;
if (--retries && r) {
log_dbg("WARNING: other process locked internal device %s, %s.",
name, retries ? "retrying remove" : "giving up");
sleep(1);
if (force && !error_target) {
if ((flags & CRYPT_DEACTIVATE_FORCE) && !error_target) {
/* If force flag is set, replace device with error, read-only target.
* it should stop processes from reading it and also removed underlying
* device from mapping, so it is usable again.
* Force flag should be used only for temporary devices, which are
* intended to work inside cryptsetup only!
* Anyway, if some process try to read temporary cryptsetup device,
* it is bug - no other process should try touch it (e.g. udev).
*/
_error_device(name, size);
_error_device(name, dmd.size);
error_target = 1;
}
}
@@ -888,7 +923,7 @@ out:
}
if (r < 0 && !reload)
_dm_simple(DM_DEVICE_REMOVE, name, 1);
_dm_remove(name, 1, 0);
out_no_removal:
if (cookie && _dm_use_udev())