Re: adding linux syscall fallocate

[Jason Thorpe <thorpej%me.com@localhost>]

> On Nov 18, 2019, at 3:32 PM, Mouse <mouse%Rodents-Montreal.ORG@localhost> wrote:
> 
> You could do that.  Creating a large hole would cost you the time to
> allocate and initialize the indirect blocks, but I suppose that's a
> factor of the block size smaller than the time it would take to
> allocate and initialize all the data blocks, so it would probably be a
> win, albeit not as much of a win as not allocating-and-filling any of
> it.

I don't see much point in deferring the allocation of any necessary indirect blocks; that's work that has to be done regardless.  What I'm really interested in avoiding is writing zeros to newly-preallocated data blocks that are just going to be overwritten by the data provided by the application anyway.  It's literally throw-away work that at best wastes time and at worst wears out the storage medium.

-- thorpej