on st_blksize value

[Andrew Snow]

Andriy Gapon wrote:

> One practical benefit can be with ZFS: if a filesystem has recordsize > PAGE_SIZE
> (e.g. default 128K) and it has checksums or compression enabled, then
> (over-)writing in blocks smaller than recordsize would require reading of a whole
> record first. 

Not strictly true: in ZFS the recordsize setting is for the maximum size 
of a record, it can still write smaller than this.  If you overwrite 1K 
in the middle of a 128K record then it should just be writing a 1K 
block.  Each block has its own checksum attached to it so there's no 
need to recalculate checksums for data that isn't changing.


- Andrew