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libdm: use dm-mod autoloading during dm_is_dm_major call if needed

For dm_is_dm_major to determine whether the major number given as
an argument belongs to a DM device, libdm code needs to know what
the actual DM major is to do the comparison.

It may happen that the dm-mod module is not loaded during this
call and so for the completness let's try our best before we start
giving various errors - we can still make use of dm-mod autoloading,
though only since kernels 2.6.36 where this feature was introduced.
This commit is contained in:
Peter Rajnoha 2014-09-12 12:49:37 +02:00
parent f0cafc9281
commit 3880ca5eca
2 changed files with 30 additions and 11 deletions

View File

@ -1,5 +1,6 @@
Version 1.02.91 -
====================================
Use dm-mod autoloading during dm_is_dm_major call if needed (kernels>=2.6.36).
Version 1.02.90 - 1st September 2014
====================================

View File

@ -336,17 +336,6 @@ static int _create_dm_bitset(void)
#endif
}
int dm_is_dm_major(uint32_t major)
{
if (!_create_dm_bitset())
return 0;
if (_dm_multiple_major_support)
return dm_bit(_dm_bitset, major) ? 1 : 0;
else
return (major == _dm_device_major) ? 1 : 0;
}
static void _close_control_fd(void)
{
if (_control_fd != -1) {
@ -423,6 +412,35 @@ bad:
#endif
}
int dm_is_dm_major(uint32_t major)
{
/*
* If dm-mod module is not loaded yet during this call, we
* can make it to load automatically in kernels >= 2.6.36
* just by opening the dm control device. However, in older
* kernels, there's nothing else we can do here - dm_is_dm_major
* will fail as it can't determine this without the module
* being loaded first - there's an error message issued for
* this scenario deeper in this code.
*/
if (!_uname())
return 0;
if (KERNEL_VERSION(_kernel_major, _kernel_minor, _kernel_release) >=
KERNEL_VERSION(2, 6, 36)) {
if (_control_fd == -1 && !_open_control())
return 0;
}
if (!_create_dm_bitset())
return 0;
if (_dm_multiple_major_support)
return dm_bit(_dm_bitset, major) ? 1 : 0;
else
return (major == _dm_device_major) ? 1 : 0;
}
static void _dm_zfree_string(char *string)
{
if (string) {