PMEM2_SOURCE_DEVICE_USC(3)

NAME

pmem2_source_device_usc() - returns the unsafe shutdown counter value of a device

SYNOPSIS

    #include <libpmem2.h>
    struct pmem2_source;
    int pmem2_source_device_usc(const struct pmem2_source *source, uint64_t *usc);

DESCRIPTION

The pmem2_source_device_usc() function retrieves the sum of the unsafe shutdown count(USC) values of all hardware devices backing the data source and stores it in *usc.

Please refer to libpmem2_unsafe_shutdown(7) for detailed description on how to properly consume this information.

RETURN VALUE

The pmem2_source_device_usc() function returns 0 on success. If the function fails, the *usc variable content is left unmodified and a negative error code is returned.

ERRORS

The pmem2_source_device_usc() can fail with the following errors:

On all systems:

•   PMEM2_E_NOSUPP - the underlying platform does not expose unsafe shutdown count information.

On Windows:

•   -errno equivalent of return code set by failing GetFinalPathNameByHandleW(), while trying to resolve volume path from the file handle.

•   -errno set by failing malloc(3), while trying to allocate a buffer for storing volume path.

•   -errno equivalent of return code set by failing CreateFileW(), while trying to obtain a handle to the volume.

•   -errno equivalent of return code set by failing DeviceIoControl(), while trying to obtain volume USC value.

On Linux:

•   -errno set by failing fstat(2), while trying to validate the file descriptor.

•   -errno set by failing ndctl_new(), while trying to initiate a new NDCTL library context.

•   -errno set by failing ndctl_dimm_get_dirty_shutdown(), while trying to obtain DIMM USC value.

SEE ALSO

fstat(2), errno(3), malloc(3), libpmem2_unsafe_shutdown(7), and <https://pmem.io>