pmemblk_read(), pmemblk_write() - read or write a block from a
block memory pool
int pmemblk_read(PMEMblkpool *pbp, void *buf, long long blockno);
int pmemblk_write(PMEMblkpool *pbp, const void *buf, long long blockno);
The pmemblk_read() function reads the block with block number
blockno from memory pool pbp into the buffer buf. Reading
a block that has never been written by pmemblk_write() will return a
block of zeroes.
The pmemblk_write() function writes a block from buf
to block number blockno in the memory pool pbp. The write is
atomic with respect to other reads and writes. In addition, the write cannot
be torn by program failure or system crash; on recovery the block is
guaranteed to contain either the old data or the new data, never a mixture
On success, the pmemblk_read() and pmemblk_write() functions
return 0. On error, they return -1 and set errno appropriately.