[PATCH] add pread operation to vfs layer

[Cole, Timothy D.]

> -----Original Message-----
> From: James Peach [mailto:jpeach at sgi.com]
> Sent: Tuesday, December 16, 2003 16:59
> To: Stefan Metzmacher
> Cc: samba-technical
> Subject: Re: [PATCH] add pread operation to vfs layer
> 
> I don't like them either. I added them to prevent a 
> performance regression
> on platforms that don't have pread/pwrite since the emulation 
> code does even
> more seeking than the original. The response to my previous 
> query showed me
> that there are people on this list who do care about samba 
> running on such
> systems.

I think emulating pread/pwrite on platforms that don't have it is less
subject to code rot and breakage than #ifdeffing out the pread/pwrite ops
entirely.

Would it be feasible to cache the effective and actual file offsets for a
file descriptor, to reduce the number of seeks needed for sequential
pwrites/preads?