Re: [RFC][PATCH] map multiple blocks at a time in mpage_readpages()

From: Badari Pulavarty
Date: Tue Feb 14 2006 - 16:50:23 EST

On Tue, 2006-02-14 at 20:27 +0100, christoph wrote:
> On Tue, Feb 14, 2006 at 09:49:07AM -0800, Badari Pulavarty wrote:
> > Hi,
> >
> > I re-did the support for mpage_readpages() to map multiple blocks
> > at a time (basically, get_blocks()). Instead of adding new
> > get_blocks() and pass it around, I use "bh->b_size" to indicate
> > how much of disk mapping we are interested in to get_block().
> >
> > This way no changes existing interfaces and no new routines need.
> > Filesystem can choose to ignore the passed in "bh->b_size" value
> > and map one block at a time (ext2, reiser3, etc..)
> Hmm. Given that we only use buffer_heads for page-cache backed I/O
> bh->b_size should always be set properly and this would be fine.
> If we could completely get rid of ->get_blocks that be a nice cleanup
> in all the fs drivers.

Yes. Sir !!
As mentioned in my note, I am already doing that :)
Only problem is, it changes the existing exported interface :(

> OTOH I still wonder whether ->get_block should
> use a small structure that just contains the information needed with
> easy to decipher names..

While ago, I did look at that. There is nothing much to trim in
the bufferhead. Most of this useful for FS, IO or JBD :(


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