pmemset API version 1.0

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pmemset_part_map() - creates a part mapping


#include <libpmemset.h>

struct pmemset_extras;
struct pmemset_part;
struct pmemset_part_descriptor;
struct pmemset_source;
int pmemset_part_map(struct pmemset_part **part_ptr,
		struct pmemset_extras *extra,
		struct pmemset_part_descriptor *desc);


The pmemset_part_map() function creates new part mapping in the virtual address space of the calling process and adds structure describing this mapping to the pmemset. It requires an address of a pointer to initialized part provided in the part_ptr parameter. A part can be created using pmemset_part_new(3) function. The mapping can later be retrieved using pmemset_first_part_map(3), pmemset_next_part_map(3) and pmemset_part_map_by_address(3) functions.

Optionally pmemset_part_map() function can take a part descriptor object passed via desc parameter. If an optional descriptor was provided then address and size of the part mapping are stored in the descriptor when this function succeeds.

Before the initialization of pmemset, a virtual memory reservation can be set in its configuration. This limits the future part mappings of initialized pmemset to the virtual address space spanned by the provided reservation. Provided reservation’s address and size will not be changed on pmemset operations. For more information about this configuration please see pmemset_config_set_reservation(3).

During the lifespan of initialized pmemset, a contiguous part coalescing feature value can be set using pmemset_set_contiguous_part_coalescing() function, modifying the default behavior of part mapping. With contiguous part coalescing feature enabled, pmemset_part_map() function tries to map each new part at the virtual memory region that is situated right after the previous mapped part memory range.

When the pmemset_part_map() function succeeds it consumes the part thereby deleting it and the variable pointed by part_ptr is set to NULL.


The pmemset_part_map() function returns 0 on success or a negative error code on failure.


The pmemset_part_map() can fail with the following errors:

  • PMEMSET_E_CANNOT_ALLOCATE_INTERNAL_STRUCTURE - an internal structure needed by the function cannot be allocated.

  • PMEMSET_E_INVALID_OFFSET_VALUE - the offset value assigned to the part is invalid. Offset value is bigger than INT64_MAX.

  • PMEMSET_E_GRANULARITY_NOT_SUPPORTED - the granularity stored in the provided part part_ptr is invalid. The concept of granularity is explained in libpmem2(7) manpage.

  • PMEMSET_E_INVALID_PMEM2_MAP - the pmem2 mapping that pmemset mapping relies on cannot be created. The error code of libpmem2(7) error is printed in the logs and can be checked for further information.

  • PMEMSET_E_LENGTH_UNALIGNED - the length of the part to be mapped is not aligned to the allocation granularity.

  • PMEMSET_E_CANNOT_COALESCE_PARTS - new part couldn’t be coalesced with previously mapped part in the pmemset. The memory range after the ending address of previous mapped part is occupied.

  • PMEMSET_E_CANNOT_TRUNCATE_SOURCE_FILE - in case of pmemset_source_from_temporary(3) or pmemset_xsource_from_file(3) PMEMSET_SOURCE_FILE_TRUNCATE_IF_NEEDED flag, temporary file created in dir cannot be truncated for the defined part size and offset.

  • -ENOMEM in case of insufficient memory to allocate an instance of struct pmemset_part_map.

  • PMEMSET_E_CANNOT_FIT_PART_MAP - in case of pmemset created from config with a reservation set, provided reservation has no space for a new part mapping


pmemset_config_set_reservation(3),pmemset_first_part_map(3), pmemset_next_part_map(3), pmemset_part_map_by_address(3), pmemset_part_new(3), pmemset_set_contiguous_part_coalescing(3), pmemset_source_from_temporary(3), pmemset_xsource_from_file(3), libpmemset(7), libpmem2(7) and

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