Re: [PATCH 1/8] exofs: Kbuild, Headers and osd utils

FUJITA Tomonori
2009-02-16T04:18:16Z

On Mon, 9 Feb 2009 15:12:09 +0200
Boaz Harrosh <bharrosh@panasas.com> wrote:

> This patch includes osd infrastructure that will be used later by
> the file system.
>
> Also the declarations of constants, on disk structures,
> and prototypes.
>
> And the Kbuild+Kconfig files needed to build the exofs module.
>
> Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
> ---
> fs/exofs/Kbuild | 30 +++++++
> fs/exofs/Kconfig | 13 +++
> fs/exofs/common.h | 181 +++++++++++++++++++++++++++++++++++++++++
> fs/exofs/exofs.h | 139 ++++++++++++++++++++++++++++++++
> fs/exofs/osd.c | 230 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> 5 files changed, 593 insertions(+), 0 deletions(-)
> create mode 100644 fs/exofs/Kbuild
> create mode 100644 fs/exofs/Kconfig
> create mode 100644 fs/exofs/common.h
> create mode 100644 fs/exofs/exofs.h
> create mode 100644 fs/exofs/osd.c

> +static void _osd_read(struct osd_request *or,
> + const struct osd_obj_id *obj, uint64_t offset, struct bio *bio)
> +{
> + osd_req_read(or, obj, bio, offset);
> + EXOFS_DBGMSG("osd_req_read(p=%llX, ob=%llX, l=%llu, of=%llu)\n",
> + _LLU(obj->partition), _LLU(obj->id), _LLU(bio->bi_size),
> + _LLU(offset));
> +}
> +
> +#ifdef __KERNEL__

Hmm?

> +static struct bio *_bio_map_pages(struct request_queue *req_q,
> + struct page **pages, unsigned page_count,
> + size_t length, gfp_t gfp_mask)
> +{
> + struct bio *bio;
> + int i;
> +
> + bio = bio_alloc(gfp_mask, page_count);
> + if (!bio) {
> + EXOFS_DBGMSG("Failed to bio_alloc page_count=%d\n", page_count);
> + return NULL;
> + }
> +
> + for (i = 0; i < page_count && length; i++) {
> + size_t use_len = min(length, PAGE_SIZE);
> +
> + if (use_len !=
> + bio_add_pc_page(req_q, bio, pages[i], use_len, 0)) {
> + EXOFS_ERR("Failed bio_add_pc_page req_q=%p pages[i]=%p "
> + "use_len=%Zd page_count=%d length=%Zd\n",
> + req_q, pages[i], use_len, page_count, length);
> + bio_put(bio);
> + return NULL;
> + }
> +
> + length -= use_len;
> + }
> +
> + WARN_ON(length);
> + return bio;
> +}

1) exofs builds bios by hand.
2) exofs passes bio to OSD SCSI ULD.

As a result, exofs and OSD SCSI ULD need to know the internal of bio,
that is, you reinvent the bio handling infrastructure, as pointed out
in another thread in scsi-ml.

_bio_map_pages is called where the VFS passes an array of a pointer to
a page frame.

Why can't you simply pass the array to OSD SCSI ULD? Then OSD SCSI ULD
can use the block layer helper functions to build a request out of
pages without knowing the internal of bio.

> +int osd_req_read_pages(struct osd_request *or,
> + const struct osd_obj_id *obj, u64 offset, u64 length,
> + struct page **pages, int page_count)
> +{
> + struct request_queue *req_q = or->osd_dev->scsi_device->request_queue;
> + struct bio *bio = _bio_map_pages(req_q, pages, page_count, length,
> + GFP_KERNEL);
> +
> + if (!bio)
> + return -ENOMEM;
> +
> + _osd_read(or, obj, offset, bio);
> + return 0;
> +}
> +#endif /* def __KERNEL__ */
> +
> +int osd_req_read_kern(struct osd_request *or,
> + const struct osd_obj_id *obj, u64 offset, void* buff, u64 len)
> +{
> + struct request_queue *req_q = or->osd_dev->scsi_device->request_queue;
> + struct bio *bio = bio_map_kern(req_q, buff, len, GFP_KERNEL);
> +
> + if (!bio)
> + return -ENOMEM;
> +
> + _osd_read(or, obj, offset, bio);
> + return 0;
> +}
> +
> +static void _osd_write(struct osd_request *or,
> + const struct osd_obj_id *obj, uint64_t offset, struct bio *bio)
> +{
> + osd_req_write(or, obj, bio, offset);
> + EXOFS_DBGMSG("osd_req_write(p=%llX, ob=%llX, l=%llu, of=%llu)\n",
> + _LLU(obj->partition), _LLU(obj->id), _LLU(bio->bi_size),
> + _LLU(offset));
> +}
> +
> +#ifdef __KERNEL__
> +int osd_req_write_pages(struct osd_request *or,
> + const struct osd_obj_id *obj, u64 offset, u64 length,
> + struct page **pages, int page_count)
> +{
> + struct request_queue *req_q = or->osd_dev->scsi_device->request_queue;
> + struct bio *bio = _bio_map_pages(req_q, pages, page_count, length,
> + GFP_KERNEL);
> +
> + if (!bio)
> + return -ENOMEM;
> +
> + _osd_write(or, obj, offset, bio);
> + return 0;
> +}
> +#endif /* def __KERNEL__ */
> +
> +int osd_req_write_kern(struct osd_request *or,
> + const struct osd_obj_id *obj, u64 offset, void* buff, u64 len)
> +{
> + struct request_queue *req_q = or->osd_dev->scsi_device->request_queue;
> + struct bio *bio = bio_map_kern(req_q, buff, len, GFP_KERNEL);
> +
> + if (!bio)
> + return -ENOMEM;
> +
> + _osd_write(or, obj, offset, bio);
> + return 0;
> +}
> --
> 1.6.0.1
>
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