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Code Releases Activity

device_manager: add device_get_uuid

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Function that is working with DM target is located within
lib/activate directory.

This function is able to use cached  dm_device_list when possible
to quickly resolve checks for device's UUID.

Function can fully replace get_dm_uuid_from_sysfs() and instead
of syscalls for open/read/close get the UUID with single ioctl.

When there is cached dm devs list, we can get many UUID from
a single syscall.
This commit is contained in:
Zdenek Kabelac 2024-05-23 01:36:50 +02:00
parent 5da282fa23
commit dac2bfe6a4
2 changed files with 32 additions and 0 deletions
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2
lib/activate/activate.h
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@ -109,6 +109,8 @@ int target_version(const char *target_name, uint32_t *maj,
int get_device_list(const struct volume_group *vg, struct dm_list **devs, int get_device_list(const struct volume_group *vg, struct dm_list **devs,
unsigned *devs_features); unsigned *devs_features);
int device_get_uuid(struct cmd_context *cmd, int major, int minor,
char *uuid_buf, size_t uuid_buf_size);
int raid4_is_supported(struct cmd_context *cmd, const struct segment_type *segtype); int raid4_is_supported(struct cmd_context *cmd, const struct segment_type *segtype);
int lvm_dm_prefix_check(int major, int minor, const char *prefix); int lvm_dm_prefix_check(int major, int minor, const char *prefix);

30
lib/activate/dev_manager.c
View File

@ -880,6 +880,36 @@ int device_is_usable(struct cmd_context *cmd, struct device *dev, struct dev_usa
return r; return r;
} }
/* Read UUID from a given DM device into buf_uuid */
int device_get_uuid(struct cmd_context *cmd, int major, int minor,
char *uuid_buf, size_t uuid_buf_size)
{
struct dm_task *dmt;
struct dm_info info;
const char *uuid;
int r = 0;
if (cmd->cache_dm_devs) {
if (dm_device_list_find_by_dev(cmd->cache_dm_devs, major, minor, NULL, &uuid)) {
dm_strncpy(uuid_buf, uuid, uuid_buf_size);
return 1;
}
uuid_buf[0] = 0;
return 0;
}
if (!(dmt = _setup_task_run(DM_DEVICE_INFO, &info, NULL, NULL, NULL,
major, minor, 0, 0, 0)))
return_0;
if (info.exists && (uuid = dm_task_get_uuid(dmt)))
r = dm_strncpy(uuid_buf, uuid, uuid_buf_size);
dm_task_destroy(dmt);
return r;
}
/* /*
* If active LVs were activated by a version of LVM2 before 2.02.00 we must * If active LVs were activated by a version of LVM2 before 2.02.00 we must
* perform additional checks to find them because they do not have the LVM- * perform additional checks to find them because they do not have the LVM-