[lkml]   [2006]   [Aug]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH 1/5] Forking ext4 filesystem from ext3 filesystem
On Thu, 10 Aug 2006 16:13:33 -0400
Jeff Garzik <> wrote:

> The sooner we kill buffer heads and use submit_bio(), the better :)

A buffer_head is a caching entity and a bio is an IO container. They're
quite separate concepts.

A buffer_head is the kernel's sole abstraction of a disk block.
Filesystems use disk blocks a lot, and they need such an abstraction.

If one was to replace buffer_heads with direct-to-BIO operations then the
filesytem would need to internally track the mapping from

page+offset+length -> disk block

and it would need to internally track the page+offset+length<->disk block
coherency state and it would need to internally perform serialisation of
access to each page+offset+length hunk of pagecache and etc and etc and
etc. Create a data structure with which to do all that and voila,
buffer_heads reinvented.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2006-08-10 22:47    [W:0.091 / U:9.196 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site