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SubjectRe: [PATCH 1/3] Vectorize aio_read/aio_write methods
On Tue, May 09, 2006 at 12:13:05PM -0700, Andrew Morton wrote:
> > there's another patch ontop which I didn't bother to redo until this is
> > accepted which kills a lot more code. After that filesystems only have
> > to implement one method each for all kinds of read/write calls. Which
> > allows to both make the mm/filemap.c far less complex and actually
> > understandable aswell as for any filesystem that uses more complex
> > read/write variants than direct filemap.c calls. In addition to these
> > simplification we also get a feature (async vectored I/O) for free.
>
> Fair enough, thanks. Simplifying filemap.c would be a win.
>
> I'll crunch on these three patches in the normal fashion. It'll be good if
> we can get the followup patch done within the next week or two so we can
> get it all tested at the same time. Although from your description it
> doesn't sound like it'll be completely trivial...

That patch is lots of tirival and boring work. If anyone wants to beat
me to it:

- in any filesystem that implements the generic_file_aio_{read,write}
directly remove these apply this patch to the file_operations
vectors:

- .read = generic_file_read,
- .write = generic_file_write,
+ .read = do_sync_read,
+ .write = do_sync_write,

Note that this does _not_ cause additional indirection for normal
sys_read/sys_write calls because they call .aio_read/.aio_write
directly. It's only needed because we have various places in the
tree that like to call .read/.write directly

- in the filesystems that implement more or less trivial wrappers
around generic_file_read/generic_file_write to the
aio_read/aio_write prototypes so they can set .read/.write as above

- after that generic_file_read/generic_file_write/generic_file_read/
generic_file_write_nolock should have no callers left and the code
for read/write in mm/filemap.c can be collapsed into very few functions.
What's left should be something like:

- generic_file_aio_read
(__generic_file_aio_read and generic_file_aio_read merged into one)
- __generic_file_aio_write
(basically the current __generic_file_aio_write_nolock)
- generic_file_aio_write_nolock
- generic_file_aio_write
(small wrappers around __generic_file_aio_write)
-
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