Re: Read/Write call interaction w/ UBC
Re: Read/Write call interaction w/ UBC
- Subject: Re: Read/Write call interaction w/ UBC
- From: "shailesh jain" <email@hidden>
- Date: Fri, 11 Jul 2008 15:56:16 -0700
1) If the user mmap's a file and makes some changes to it and then calls
read() system call (without msync'ing), is it the responsibility of a filesystem
to flush the changes that could have been made by mmap system call before
actually reading the file ?
2) Also, while referring to source for smbfs, I came across a comment that said " we shall maintain synchronization between mmap and read/write by using UPL". Isn't just flushing mmaped pages enough ?
/Shail
On Tue, Jul 8, 2008 at 10:46 PM, Michael Smith <
email@hidden> wrote:
On Jul 8, 2008, at 2:25 AM, Terry Lambert wrote:
On Jul 7, 2008, at 7:21 PM, shailesh jain <email@hidden> wrote:
I am writing a file system that does not support caching. I wanted to know, If by just passing
NO_CACHE and CANT_CACHE option, I can disable entire caching ?
As of my understanding, the options are just to disable name lookup etc caching and it cannot
disable file content caching i.e where UBC comes into play. Can I disable file content caching i.e UBC ? (set it to UBC_INFO_NULL ?).
Also, apple docs says that UBC for apple is different from FreeBSD. I wanted to know in what respect ?
Read the sources. I put massive block comments in the UBC code for just such an emergency. 8-).
= Mike
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