Messages in this thread | | | Date | Thu, 10 Aug 2006 13:27:20 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 1/5] Forking ext4 filesystem from ext3 filesystem |
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On Thu, 10 Aug 2006 16:13:33 -0400 Jeff Garzik <jeff@garzik.org> 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 majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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