Re: ext2 on a CD-RW

[Jens Axboe <axboe@suse.de>]

On Fri, Jan 02 2004, Peter Osterlund wrote:
> Jens Axboe <axboe@suse.de> writes:
> 
> > I just looked but could not find anything about it, there's been some
> > talk on this list. But it doesn't look like it ever got documented in
> > text writing. That needs to be fixed for sure, thanks for the patch. It
> > probably wants documenting in fs/bio.c:bio_add_page() too.
> 
> OK, here is an updated patch.
> 
> Improved documentation for blk_queue_merge_bvec() and bio_add_page().
> 
> 
>  linux-petero/drivers/block/ll_rw_blk.c |    8 +++++---
>  linux-petero/fs/bio.c                  |    4 +++-
>  2 files changed, 8 insertions(+), 4 deletions(-)
> 
> diff -puN drivers/block/ll_rw_blk.c~block-api-doc drivers/block/ll_rw_blk.c
> --- linux/drivers/block/ll_rw_blk.c~block-api-doc	2004-01-02 13:54:38.000000000 +0100
> +++ linux-petero/drivers/block/ll_rw_blk.c	2004-01-02 13:55:50.000000000 +0100
> @@ -173,9 +173,11 @@ EXPORT_SYMBOL(blk_queue_prep_rq);
>   * are dynamic, and thus we have to query the queue whether it is ok to
>   * add a new bio_vec to a bio at a given offset or not. If the block device
>   * has such limitations, it needs to register a merge_bvec_fn to control
> - * the size of bio's sent to it. Per default now merge_bvec_fn is defined for
> - * a queue, and only the fixed limits are honored.
> - *
> + * the size of bio's sent to it. Note that a block device *must* allow a
> + * single page to be added to an empty bio. The block device driver may want
> + * to use the bio_split() function to deal with these bio's. Per default
> + * no merge_bvec_fn is defined for a queue, and only the fixed limits are
> + * honored.
>   */
>  void blk_queue_merge_bvec(request_queue_t *q, merge_bvec_fn *mbfn)
>  {
> diff -puN fs/bio.c~block-api-doc fs/bio.c
> --- linux/fs/bio.c~block-api-doc	2004-01-02 14:00:13.000000000 +0100
> +++ linux-petero/fs/bio.c	2004-01-02 14:37:41.000000000 +0100
> @@ -290,7 +290,9 @@ int bio_get_nr_vecs(struct block_device 
>   *
>   *	Attempt to add a page to the bio_vec maplist. This can fail for a
>   *	number of reasons, such as the bio being full or target block
> - *	device limitations.
> + *	device limitations. The target block device must not disallow bio's

That may not be unparsable, but I'll remove the double negative :).
Otherwise comitted, thanks.

-- 
Jens Axboe