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Message-ID: <4A5E168B.8010809@cisco.com>
Date: Wed, 15 Jul 2009 10:48:59 -0700
From: Joe Eykholt <jeykholt@...co.com>
To: Boaz Harrosh <bharrosh@...asas.com>
CC: Vladislav Bolkhovitin <vst@...b.net>, Tejun Heo <tj@...nel.org>,
linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
scst-devel@...ts.sourceforge.net,
James Bottomley <James.Bottomley@...senPartnership.com>,
FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>,
Jens Axboe <jens.axboe@...cle.com>
Subject: Re: [PATCH v2]: New implementation of scsi_execute_async()
Boaz Harrosh wrote:
> On 07/14/2009 07:17 PM, Vladislav Bolkhovitin wrote:
>> This patch reimplements scsi_execute_async(). In the new version it's a lot less
>> hackish and also has additional features. Namely:
>>
>> 1. Possibility to insert commands both in tail and in head of the queue.
>>
>> 2. Possibility to explicitly specify if the last SG element has space for padding.
>>
>> This patch based on the previous patches posted by Tejun Heo. Comparing to them
>> it has the following improvements:
>>
>> 1. It uses BIOs chaining instead of kmalloc()ing the whole bio.
>>
>> 2. It uses SGs chaining instead of kmalloc()ing one big SG in case if direct
>> mapping failed (e.g. because of DMA alignment or padding).
>>
>> 3. If direct mapping failed, if possible, it copies only the last SG element,
>> not the whole SG.
>>
>> 4. When needed, copy_page() is used instead of memcpy() to copy the whole pages.
>>
>> Also this patch adds and exports functions sg_copy() and sg_copy_elem(), which
>> cop one SG to another and one SG element to another respectively.
>>
>> At the moment SCST is the only user of this functionality. It needs it, because
>> its target drivers, which are, basically, SCSI drivers, can deal only with SGs,
>> not with BIOs. But, according the latest discussions, there are other potential
>> users for of this functionality, so I'm sending this patch in a hope that it will be
>> also useful for them and eventually will be merged in the mainline kernel.
>>
>> This patch requires previously sent patch with subject "[PATCH]: Rename REQ_COPY_USER
>> to more descriptive REQ_HAS_TAIL_SPACE_FOR_PADDING".
>>
>> It's against 2.6.30.1, but if necessary, I can update it to any necessary
>> kernel version.
>>
>> Signed-off-by: Vladislav Bolkhovitin <vst@...b.net>
>>
>> block/blk-map.c | 408 ++++++++++++++++++++++++++++++++++++++++++++
>> drivers/scsi/scsi_lib.c | 108 +++++++++++
>> include/linux/blkdev.h | 3
>> include/linux/scatterlist.h | 7
>> include/scsi/scsi_device.h | 11 +
>> lib/scatterlist.c | 147 +++++++++++++++
>> 6 files changed, 683 insertions(+), 1 deletion(-)
>>
>> diff -upkr linux-2.6.30.1/block/blk-map.c linux-2.6.30.1/block/blk-map.c
>> --- linux-2.6.30.1/block/blk-map.c 2009-07-10 21:13:25.000000000 +0400
>> +++ linux-2.6.30.1/block/blk-map.c 2009-07-14 19:24:36.000000000 +0400
>> @@ -5,6 +5,7 @@
>> #include <linux/module.h>
>> #include <linux/bio.h>
>> #include <linux/blkdev.h>
>> +#include <linux/scatterlist.h>
>> #include <scsi/sg.h> /* for struct sg_iovec */
>>
>> #include "blk.h"
>> @@ -272,6 +273,413 @@ int blk_rq_unmap_user(struct bio *bio)
>> }
>> EXPORT_SYMBOL(blk_rq_unmap_user);
>>
>> +struct blk_kern_sg_hdr {
>> + struct scatterlist *orig_sgp;
>> + union {
>> + struct sg_table new_sg_table;
>> + struct scatterlist *saved_sg;
>> + };
>
> There is a struct scatterlist * inside struct sg_table
> just use that. No need for a union. (It's not like your saving
> space). In the tail case nents == 1.
> (orig_nents==0 and loose the tail_only)
>
>> + bool tail_only;
>> +};
>> +
>> +#define BLK_KERN_SG_HDR_ENTRIES (1 + (sizeof(struct blk_kern_sg_hdr) - 1) / \
>> + sizeof(struct scatterlist))
>> +
>> +/**
>> + * blk_rq_unmap_kern_sg - "unmaps" data buffers in the request
>> + * @req: request to unmap
>> + * @do_copy: sets copy data between buffers, if needed, or not
>> + *
>> + * Description:
>> + * It frees all additional buffers allocated for SG->BIO mapping.
>> + */
>> +void blk_rq_unmap_kern_sg(struct request *req, int do_copy)
> +void blk_rq_unmap_kern_sg(struct request *req, struct blk_kern_sg_hdr *hdr, int do_copy)
>
>> +{
>> + struct blk_kern_sg_hdr *hdr = (struct blk_kern_sg_hdr *)req->end_io_data;
>> +
>
> Again still req->end_io_data can not be used. You can add a pointer to the call
> or use/add another member.
>
>> + if (hdr == NULL)
>> + goto out;
>> +
>> + if (hdr->tail_only) {
>> + /* Tail element only was copied */
>> + struct scatterlist *saved_sg = hdr->saved_sg;
>> + struct scatterlist *tail_sg = hdr->orig_sgp;
>> +
>> + if ((rq_data_dir(req) == READ) && do_copy)
>> + sg_copy_elem(saved_sg, tail_sg, tail_sg->length,
>> + KM_BIO_DST_IRQ, KM_BIO_SRC_IRQ);
>> +
>> + __free_pages(sg_page(tail_sg), get_order(tail_sg->length));
>> + *tail_sg = *saved_sg;
>> + kfree(hdr);
>> + } else {
>> + /* The whole SG was copied */
>> + struct sg_table new_sg_table = hdr->new_sg_table;
>> + struct scatterlist *new_sgl = new_sg_table.sgl +
>> + BLK_KERN_SG_HDR_ENTRIES;
>> + struct scatterlist *orig_sgl = hdr->orig_sgp;
>> +
>> + if ((rq_data_dir(req) == READ) && do_copy)
>> + sg_copy(orig_sgl, new_sgl, 0, KM_BIO_DST_IRQ,
>> + KM_BIO_SRC_IRQ);
>> +
>> + sg_free_table(&new_sg_table);
>> + }
>> +
>> +out:
>> + return;
>> +}
>> +EXPORT_SYMBOL(blk_rq_unmap_kern_sg);
>> +
>> +static int blk_rq_handle_align_tail_only(struct request *rq,
>> + struct scatterlist *sg_to_copy,
>> + gfp_t gfp, gfp_t page_gfp)
>> +{
>> + int res = 0;
>> + struct scatterlist *tail_sg = sg_to_copy;
>> + struct scatterlist *saved_sg;
>> + struct blk_kern_sg_hdr *hdr;
>> + int saved_sg_nents;
>> + struct page *pg;
>> +
>> + saved_sg_nents = 1 + BLK_KERN_SG_HDR_ENTRIES;
>> +
>> + saved_sg = kmalloc(sizeof(*saved_sg) * saved_sg_nents, gfp);
>> + if (saved_sg == NULL)
>> + goto out_nomem;
>> +
>> + sg_init_table(saved_sg, saved_sg_nents);
>> +
>> + hdr = (struct blk_kern_sg_hdr *)saved_sg;
>> + saved_sg += BLK_KERN_SG_HDR_ENTRIES;
>> + saved_sg_nents -= BLK_KERN_SG_HDR_ENTRIES;
>> +
>> + hdr->tail_only = true;
>> + hdr->orig_sgp = tail_sg;
>> + hdr->saved_sg = saved_sg;
>> +
>> + *saved_sg = *tail_sg;
>> +
>> + pg = alloc_pages(page_gfp, get_order(tail_sg->length));
>> + if (pg == NULL)
>> + goto err_free_saved_sg;
>> +
>> + sg_assign_page(tail_sg, pg);
>> + tail_sg->offset = 0;
>> +
>> + if (rq_data_dir(rq) == WRITE)
>> + sg_copy_elem(tail_sg, saved_sg, saved_sg->length,
>> + KM_USER1, KM_USER0);
>> +
>> + rq->end_io_data = hdr;
>
> Perhaps return it to the user or pass an **void output
> parameter to be set, or again another member
>
>> + rq->cmd_flags |= REQ_HAS_TAIL_SPACE_FOR_PADDING;
>> +
>> +out:
>> + return res;
>> +
>> +err_free_saved_sg:
>> + kfree(saved_sg);
>> +
>> +out_nomem:
>> + res = -ENOMEM;
>> + goto out;
>> +}
>> +
>> +static int blk_rq_handle_align(struct request *rq, struct scatterlist **psgl,
>> + int *pnents, struct scatterlist *sgl_to_copy,
>> + int nents_to_copy, gfp_t gfp, gfp_t page_gfp)
>> +{
>> + int res = 0, i;
>> + struct scatterlist *sgl = *psgl;
>> + int nents = *pnents;
>> + struct sg_table sg_table;
>> + struct scatterlist *sg;
>> + struct scatterlist *new_sgl;
>> + size_t len = 0, to_copy;
>> + int new_sgl_nents;
>> + struct blk_kern_sg_hdr *hdr;
>> +
>> + if (sgl != sgl_to_copy) {
>> + /* copy only the last element */
>> + res = blk_rq_handle_align_tail_only(rq, sgl_to_copy,
>> + gfp, page_gfp);
>> + if (res == 0)
>> + goto out;
>> + /* else go through */
>> + }
>> +
>> + for_each_sg(sgl, sg, nents, i)
>> + len += sg->length;
>> + to_copy = len;
>> +
>> + new_sgl_nents = PFN_UP(len) + BLK_KERN_SG_HDR_ENTRIES;
>> +
>> + res = sg_alloc_table(&sg_table, new_sgl_nents, gfp);
>> + if (res != 0)
>> + goto out;
>> +
>> + new_sgl = sg_table.sgl;
>> + hdr = (struct blk_kern_sg_hdr *)new_sgl;
>> + new_sgl += BLK_KERN_SG_HDR_ENTRIES;
>> + new_sgl_nents -= BLK_KERN_SG_HDR_ENTRIES;
>> +
>> + hdr->tail_only = false;
>> + hdr->orig_sgp = sgl;
>> + hdr->new_sg_table = sg_table;
>> +
>> + for_each_sg(new_sgl, sg, new_sgl_nents, i) {
>> + struct page *pg;
>> +
>> + pg = alloc_page(page_gfp);
>> + if (pg == NULL)
>> + goto err_free_new_sgl;
>> +
>> + sg_assign_page(sg, pg);
>> + sg->length = min_t(size_t, PAGE_SIZE, len);
>> +
>> + len -= PAGE_SIZE;
>> + }
>> +
>> + if (rq_data_dir(rq) == WRITE) {
>> + /*
>> + * We need to limit amount of copied data to to_copy, because
>> + * sgl might have the last element not marked as last in
>> + * SG chaining.
>> + */
>> + sg_copy(new_sgl, sgl, to_copy, KM_USER0, KM_USER1);
>> + }
>> +
>> + rq->end_io_data = hdr;
>> + rq->cmd_flags |= REQ_HAS_TAIL_SPACE_FOR_PADDING;
>> +
>> + *psgl = new_sgl;
>> + *pnents = new_sgl_nents;
>> +
>> +out:
>> + return res;
>> +
>> +err_free_new_sgl:
>> + for_each_sg(new_sgl, sg, new_sgl_nents, i) {
>> + struct page *pg = sg_page(sg);
>> + if (pg == NULL)
>> + break;
>> + __free_page(pg);
>> + }
>> + sg_free_table(&sg_table);
>> +
>> + res = -ENOMEM;
>> + goto out;
>> +}
>> +
>> +static void bio_map_kern_endio(struct bio *bio, int err)
>> +{
>> + bio_put(bio);
>> +}
>> +
>> +static int __blk_rq_map_kern_sg(struct request *rq, struct scatterlist *sgl,
>> + int nents, gfp_t gfp, struct scatterlist **sgl_to_copy,
>> + int *nents_to_copy)
>> +{
>> + int res;
>> + struct request_queue *q = rq->q;
>> + int rw = rq_data_dir(rq);
>> + int max_nr_vecs, i;
>> + size_t tot_len;
>> + bool need_new_bio;
>> + struct scatterlist *sg, *prev_sg = NULL;
>> + struct bio *bio = NULL, *hbio = NULL, *tbio = NULL;
>> +
>> + *sgl_to_copy = NULL;
>> +
>> + if (unlikely((sgl == 0) || (nents <= 0))) {
>> + WARN_ON(1);
>> + res = -EINVAL;
>> + goto out;
>> + }
>> +
>> + /*
>> + * Let's keep each bio allocation inside a single page to decrease
>> + * probability of failure.
>> + */
>> + max_nr_vecs = min_t(size_t,
>> + ((PAGE_SIZE - sizeof(struct bio)) / sizeof(struct bio_vec)),
>> + BIO_MAX_PAGES);
>> +
>> + need_new_bio = true;
>> + tot_len = 0;
>> + for_each_sg(sgl, sg, nents, i) {
>> + struct page *page = sg_page(sg);
>> + void *page_addr = page_address(page);
>> + size_t len = sg->length, l;
>> + size_t offset = sg->offset;
>> +
>> + tot_len += len;
>> + prev_sg = sg;
>> +
>> + /*
>> + * Each segment must be aligned on DMA boundary and
>> + * not on stack. The last one may have unaligned
>> + * length as long as the total length is aligned to
>> + * DMA padding alignment.
>> + */
>> + if (i == nents - 1)
>> + l = 0;
>> + else
>> + l = len;
>> + if (((sg->offset | l) & queue_dma_alignment(q)) ||
>> + (page_addr && object_is_on_stack(page_addr + sg->offset))) {
>> + res = -EINVAL;
>> + goto out_need_copy;
>> + }
>> +
>> + while (len > 0) {
>> + size_t bytes;
>> + int rc;
>> +
>> + if (need_new_bio) {
>> + bio = bio_kmalloc(gfp, max_nr_vecs);
>> + if (bio == NULL) {
>> + res = -ENOMEM;
>> + goto out_free_bios;
>> + }
>> +
>> + if (rw == WRITE)
>> + bio->bi_rw |= 1 << BIO_RW;
>> +
>> + bio->bi_end_io = bio_map_kern_endio;
>> +
>> + if (hbio == NULL)
>> + hbio = tbio = bio;
>> + else
>> + tbio = tbio->bi_next = bio;
>> + }
>> +
>> + bytes = min_t(size_t, len, PAGE_SIZE - offset);
>> +
>> + rc = bio_add_pc_page(q, bio, page, bytes, offset);
>> + if (rc < bytes) {
>> + if (unlikely(need_new_bio || (rc < 0))) {
>> + if (rc < 0)
>> + res = rc;
>> + else
>> + res = -EIO;
>> + goto out_need_copy;
>> + } else {
>> + need_new_bio = true;
>> + len -= rc;
>> + offset += rc;
>> + continue;
>> + }
>> + }
>> +
>> + need_new_bio = false;
>> + offset = 0;
>> + len -= bytes;
>> + page = nth_page(page, 1);
>> + }
>> + }
>> +
>> + if (hbio == NULL) {
>> + res = -EINVAL;
>> + goto out_free_bios;
>> + }
>> +
>> + /* Total length must be aligned on DMA padding alignment */
>> + if ((tot_len & q->dma_pad_mask) &&
>> + !(rq->cmd_flags & REQ_HAS_TAIL_SPACE_FOR_PADDING)) {
>> + res = -EINVAL;
>> + if (sgl->offset == 0) {
>> + *sgl_to_copy = prev_sg;
>> + *nents_to_copy = 1;
>> + goto out_free_bios;
>> + } else
>> + goto out_need_copy;
>> + }
>> +
>> + while (hbio != NULL) {
>> + bio = hbio;
>> + hbio = hbio->bi_next;
>> + bio->bi_next = NULL;
>> +
>> + blk_queue_bounce(q, &bio);
>
> I do not understand. If you are bouncing on the bio level.
> why do you need to do all the alignment checks and
> sg-bouncing + tail handling all this is done again on the bio
> level.
>
> It looks to me that perhaps you did not understand Tejun's code
> His code, as I remember, was on the bio level, but here you
> are duplicating what is done in bio level.
>
> But maybe I don't understand. Tejun?
>
>> +
>> + res = blk_rq_append_bio(q, rq, bio);
>> + if (unlikely(res != 0)) {
>> + bio->bi_next = hbio;
>> + hbio = bio;
>> + goto out_free_bios;
>> + }
>> + }
>> +
>> + rq->buffer = rq->data = NULL;
>> +
>> +out:
>> + return res;
>> +
>> +out_need_copy:
>> + *sgl_to_copy = sgl;
>> + *nents_to_copy = nents;
>> +
>> +out_free_bios:
>> + while (hbio != NULL) {
>> + bio = hbio;
>> + hbio = hbio->bi_next;
>> + bio_put(bio);
>> + }
>> + goto out;
>> +}
>> +
>> +/**
>> + * blk_rq_map_kern_sg - map kernel data to a request, for REQ_TYPE_BLOCK_PC
>> + * @rq: request to fill
>> + * @sgl: area to map
>> + * @nents: number of elements in @sgl
>> + * @gfp: memory allocation flags
>> + *
>> + * Description:
>> + * Data will be mapped directly if possible. Otherwise a bounce
>> + * buffer will be used.
>> + */
>> +int blk_rq_map_kern_sg(struct request *rq, struct scatterlist *sgl,
>> + int nents, gfp_t gfp)
>> +{
>> + int res;
>> + struct scatterlist *sg_to_copy = NULL;
>> + int nents_to_copy = 0;
>> +
>> + if (unlikely((sgl == 0) || (sgl->length == 0) ||
>> + (nents <= 0) || (rq->end_io_data != NULL))) {
>> + WARN_ON(1);
>> + res = -EINVAL;
>> + goto out;
>> + }
>> +
>> + res = __blk_rq_map_kern_sg(rq, sgl, nents, gfp, &sg_to_copy,
>> + &nents_to_copy);
>> + if (unlikely(res != 0)) {
>> + if (sg_to_copy == NULL)
>> + goto out;
>> +
>> + res = blk_rq_handle_align(rq, &sgl, &nents, sg_to_copy,
>> + nents_to_copy, gfp, rq->q->bounce_gfp | gfp);
>> + if (unlikely(res != 0))
>> + goto out;
>> +
>> + res = __blk_rq_map_kern_sg(rq, sgl, nents, gfp, &sg_to_copy,
>> + &nents_to_copy);
>> + if (res != 0) {
>> + blk_rq_unmap_kern_sg(rq, 0);
>> + goto out;
>> + }
>> + }
>> +
>> + rq->buffer = rq->data = NULL;
>> +
>> +out:
>> + return res;
>> +}
>> +EXPORT_SYMBOL(blk_rq_map_kern_sg);
>> +
>> /**
>> * blk_rq_map_kern - map kernel data to a request, for REQ_TYPE_BLOCK_PC usage
>> * @q: request queue where request should be inserted
>> diff -upkr linux-2.6.30.1/drivers/scsi/scsi_lib.c linux-2.6.30.1/drivers/scsi/scsi_lib.c
>> --- linux-2.6.30.1/drivers/scsi/scsi_lib.c 2009-07-10 21:13:25.000000000 +0400
>> +++ linux-2.6.30.1/drivers/scsi/scsi_lib.c 2009-07-08 21:24:29.000000000 +0400
>> @@ -277,6 +277,100 @@ int scsi_execute_req(struct scsi_device
>> }
>> EXPORT_SYMBOL(scsi_execute_req);
>>
>> +struct scsi_io_context {
>> + void *blk_data;
>> + void *data;
>> + void (*done)(void *data, char *sense, int result, int resid);
>> + char sense[SCSI_SENSE_BUFFERSIZE];
>> +};
>> +
>> +static struct kmem_cache *scsi_io_context_cache;
>> +
>> +static void scsi_end_async(struct request *req, int error)
>> +{
>> + struct scsi_io_context *sioc = req->end_io_data;
>> +
>> + req->end_io_data = sioc->blk_data;
>> + blk_rq_unmap_kern_sg(req, (error == 0));
>> +
>> + if (sioc->done)
>> + sioc->done(sioc->data, sioc->sense, req->errors, req->data_len);
>> +
>> + kmem_cache_free(scsi_io_context_cache, sioc);
>> + __blk_put_request(req->q, req);
>
> There is nothing scsi here. Do it in the caller
>
>> +}
>> +
>> +/**
>> + * scsi_execute_async - insert request
>> + * @sdev: scsi device
>> + * @cmd: scsi command
>> + * @cmd_len: length of scsi cdb
>> + * @data_direction: DMA_TO_DEVICE, DMA_FROM_DEVICE, or DMA_NONE
>> + * @sgl: data buffer scatterlist
>> + * @nents: number of elements in the sgl
>> + * @timeout: request timeout in seconds
>> + * @retries: number of times to retry request
>> + * @privdata: data passed to done()
>> + * @done: callback function when done
>> + * @gfp: memory allocation flags
>> + * @flags: one or more SCSI_ASYNC_EXEC_FLAG_* flags
>> + */
>> +int scsi_execute_async(struct scsi_device *sdev, const unsigned char *cmd,
>> + int cmd_len, int data_direction, struct scatterlist *sgl,
>> + int nents, int timeout, int retries, void *privdata,
>> + void (*done)(void *, char *, int, int), gfp_t gfp,
>> + int flags)
>> +{
>> + struct request *req;
>> + struct scsi_io_context *sioc;
>> + int err = 0;
>> + int write = (data_direction == DMA_TO_DEVICE);
>> +
>> + sioc = kmem_cache_zalloc(scsi_io_context_cache, gfp);
>> + if (sioc == NULL)
>> + return DRIVER_ERROR << 24;
>> +
>> + req = blk_get_request(sdev->request_queue, write, gfp);
>> + if (req == NULL)
>> + goto free_sense;
>> + req->cmd_type = REQ_TYPE_BLOCK_PC;
>> + req->cmd_flags |= REQ_QUIET;
>> +
>
> Block API
>
>> + if (flags & SCSI_ASYNC_EXEC_FLAG_HAS_TAIL_SPACE_FOR_PADDING)
>> + req->cmd_flags |= REQ_HAS_TAIL_SPACE_FOR_PADDING;
>> +
>> + if (sgl != NULL) {
>> + err = blk_rq_map_kern_sg(req, sgl, nents, gfp);
>> + if (err)
>> + goto free_req;
>> + }
>> +
>
> All block API nothing scsi here
>
>> + sioc->blk_data = req->end_io_data;
>> + sioc->data = privdata;
>> + sioc->done = done;
>> +
>> + req->cmd_len = cmd_len;
>> + memset(req->cmd, 0, BLK_MAX_CDB); /* ATAPI hates garbage after CDB */
>> + memcpy(req->cmd, cmd, req->cmd_len);
>
> Does not support large commands.
> Also a blk API nothing scsi about it
>
>> + req->sense = sioc->sense;
>> + req->sense_len = 0;
>> + req->timeout = timeout;
>> + req->retries = retries;
>> + req->end_io_data = sioc;
>> +
>> + blk_execute_rq_nowait(req->q, NULL, req,
>> + flags & SCSI_ASYNC_EXEC_FLAG_AT_HEAD, scsi_end_async);
>> + return 0;
>> +
>> +free_req:
>> + blk_put_request(req);
>> +
>> +free_sense:
>> + kmem_cache_free(scsi_io_context_cache, sioc);
>> + return DRIVER_ERROR << 24;
>> +}
>> +EXPORT_SYMBOL_GPL(scsi_execute_async);
>> +
>
> The complete scsi bits are not needed. They have nothing to do with
> scsi. If at all this should go into black layer.
> scsi_lib is not a wrapper around blk API.
>
>> /*
>> * Function: scsi_init_cmd_errh()
>> *
>> @@ -1743,12 +1837,20 @@ int __init scsi_init_queue(void)
>> {
>> int i;
>>
>> + scsi_io_context_cache = kmem_cache_create("scsi_io_context",
>> + sizeof(struct scsi_io_context),
>> + 0, 0, NULL);
>> + if (!scsi_io_context_cache) {
>> + printk(KERN_ERR "SCSI: can't init scsi io context cache\n");
>> + return -ENOMEM;
>> + }
>> +
>> scsi_sdb_cache = kmem_cache_create("scsi_data_buffer",
>> sizeof(struct scsi_data_buffer),
>> 0, 0, NULL);
>> if (!scsi_sdb_cache) {
>> printk(KERN_ERR "SCSI: can't init scsi sdb cache\n");
>> - return -ENOMEM;
>> + goto cleanup_io_context;
>> }
>>
>> for (i = 0; i < SG_MEMPOOL_NR; i++) {
>> @@ -1784,6 +1886,9 @@ cleanup_sdb:
>> }
>> kmem_cache_destroy(scsi_sdb_cache);
>>
>> +cleanup_io_context:
>> + kmem_cache_destroy(scsi_io_context_cache);
>> +
>> return -ENOMEM;
>> }
>>
>> @@ -1791,6 +1896,7 @@ void scsi_exit_queue(void)
>> {
>> int i;
>>
>> + kmem_cache_destroy(scsi_io_context_cache);
>> kmem_cache_destroy(scsi_sdb_cache);
>>
>> for (i = 0; i < SG_MEMPOOL_NR; i++) {
>> diff -upkr linux-2.6.30.1/include/linux/blkdev.h linux-2.6.30.1/include/linux/blkdev.h
>> --- linux-2.6.30.1/include/linux/blkdev.h 2009-07-10 21:13:25.000000000 +0400
>> +++ linux-2.6.30.1/include/linux/blkdev.h 2009-07-13 13:56:45.000000000 +0400
>> @@ -807,6 +807,9 @@ extern int blk_rq_map_kern(struct reques
>> extern int blk_rq_map_user_iov(struct request_queue *, struct request *,
>> struct rq_map_data *, struct sg_iovec *, int,
>> unsigned int, gfp_t);
>> +extern int blk_rq_map_kern_sg(struct request *rq,
>> + struct scatterlist *sgl, int nents, gfp_t gfp);
>> +extern void blk_rq_unmap_kern_sg(struct request *req, int do_copy);
>> extern int blk_execute_rq(struct request_queue *, struct gendisk *,
>> struct request *, int);
>> extern void blk_execute_rq_nowait(struct request_queue *, struct gendisk *,
>> diff -upkr linux-2.6.30.1/include/linux/scatterlist.h linux-2.6.30.1/include/linux/scatterlist.h
>> --- linux-2.6.30.1/include/linux/scatterlist.h 2009-06-10 07:05:27.000000000 +0400
>> +++ linux-2.6.30.1/include/linux/scatterlist.h 2009-07-13 13:56:24.000000000 +0400
>> @@ -218,6 +218,13 @@ size_t sg_copy_from_buffer(struct scatte
>> size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
>> void *buf, size_t buflen);
>>
>> +int sg_copy_elem(struct scatterlist *dst_sg, struct scatterlist *src_sg,
>> + size_t copy_len, enum km_type d_km_type,
>> + enum km_type s_km_type);
>> +int sg_copy(struct scatterlist *dst_sg,
>> + struct scatterlist *src_sg, size_t copy_len,
>> + enum km_type d_km_type, enum km_type s_km_type);
>> +
>> /*
>> * Maximum number of entries that will be allocated in one piece, if
>> * a list larger than this is required then chaining will be utilized.
>> diff -upkr linux-2.6.30.1/include/scsi/scsi_device.h linux-2.6.30.1/include/scsi/scsi_device.h
>> --- linux-2.6.30.1/include/scsi/scsi_device.h 2009-07-10 21:13:25.000000000 +0400
>> +++ linux-2.6.30.1/include/scsi/scsi_device.h 2009-07-08 21:24:29.000000000 +0400
>> @@ -372,6 +372,17 @@ extern int scsi_execute_req(struct scsi_
>> struct scsi_sense_hdr *, int timeout, int retries,
>> int *resid);
>>
>> +#define SCSI_ASYNC_EXEC_FLAG_AT_HEAD 1
>> +#define SCSI_ASYNC_EXEC_FLAG_HAS_TAIL_SPACE_FOR_PADDING 2
>> +
>
> Just use blk API directly inside the caller
>
>> +#define SCSI_EXEC_REQ_FIFO_DEFINED
>> +extern int scsi_execute_async(struct scsi_device *sdev, const unsigned char *cmd,
>> + int cmd_len, int data_direction,
>> + struct scatterlist *sgl, int nents, int timeout,
>> + int retries, void *privdata,
>> + void (*done)(void *, char *, int, int),
>> + gfp_t gfp, int flags);
>> +
>> static inline int __must_check scsi_device_reprobe(struct scsi_device *sdev)
>> {
>> return device_reprobe(&sdev->sdev_gendev);
>> diff -upkr linux-2.6.30.1/lib/scatterlist.c linux-2.6.30.1/lib/scatterlist.c
>> --- linux-2.6.30.1/lib/scatterlist.c 2009-06-10 07:05:27.000000000 +0400
>> +++ linux-2.6.30.1/lib/scatterlist.c 2009-07-14 19:22:49.000000000 +0400
>> @@ -485,3 +485,150 @@ size_t sg_copy_to_buffer(struct scatterl
>> return sg_copy_buffer(sgl, nents, buf, buflen, 1);
>> }
>> EXPORT_SYMBOL(sg_copy_to_buffer);
>> +
>> +/*
>> + * Can switch to the next dst_sg element, so, to copy to strictly only
>> + * one dst_sg element, it must be either last in the chain, or
>> + * copy_len == dst_sg->length.
>> + */
>> +static int __sg_copy_elem(struct scatterlist **pdst_sg, size_t *pdst_len,
>> + size_t *pdst_offs, struct scatterlist *src_sg,
>> + size_t copy_len,
>> + enum km_type d_km_type, enum km_type s_km_type)
>> +{
>> + int res = 0;
>> + struct scatterlist *dst_sg;
>> + size_t src_len, dst_len, src_offs, dst_offs;
>> + struct page *src_page, *dst_page;
>> +
>> + if (copy_len == 0)
>> + copy_len = 0x7FFFFFFF; /* copy all */
>> +
>> + dst_sg = *pdst_sg;
>> + dst_len = *pdst_len;
>> + dst_offs = *pdst_offs;
>> + dst_page = sg_page(dst_sg);
>> +
>> + src_page = sg_page(src_sg);
>> + src_len = src_sg->length;
>> + src_offs = src_sg->offset;
>> +
>> + do {
>> + void *saddr, *daddr;
>> + size_t n;
>> +
>> + saddr = kmap_atomic(src_page +
>> + (src_offs >> PAGE_SHIFT), s_km_type) +
>> + (src_offs & ~PAGE_MASK);
>> + daddr = kmap_atomic(dst_page +
>> + (dst_offs >> PAGE_SHIFT), d_km_type) +
>> + (dst_offs & ~PAGE_MASK);
>> +
>> + if (((src_offs & ~PAGE_MASK) == 0) &&
>> + ((dst_offs & ~PAGE_MASK) == 0) &&
>> + (src_len >= PAGE_SIZE) && (dst_len >= PAGE_SIZE) &&
>> + (copy_len >= PAGE_SIZE)) {
>> + copy_page(daddr, saddr);
>> + n = PAGE_SIZE;
>> + } else {
>> + n = min_t(size_t, PAGE_SIZE - (dst_offs & ~PAGE_MASK),
>> + PAGE_SIZE - (src_offs & ~PAGE_MASK));
>> + n = min(n, src_len);
>> + n = min(n, dst_len);
>> + n = min_t(size_t, n, copy_len);
>> + memcpy(daddr, saddr, n);
>> + }
>> + dst_offs += n;
>> + src_offs += n;
>> +
>> + kunmap_atomic(saddr, s_km_type);
>> + kunmap_atomic(daddr, d_km_type);
>> +
>> + res += n;
>> + copy_len -= n;
>> + if (copy_len == 0)
>> + goto out;
>> +
>> + src_len -= n;
>> + dst_len -= n;
>> + if (dst_len == 0) {
>> + dst_sg = sg_next(dst_sg);
>> + if (dst_sg == NULL)
>> + goto out;
>> + dst_page = sg_page(dst_sg);
>> + dst_len = dst_sg->length;
>> + dst_offs = dst_sg->offset;
>> + }
>> + } while (src_len > 0);
>> +
>> +out:
>> + *pdst_sg = dst_sg;
>> + *pdst_len = dst_len;
>> + *pdst_offs = dst_offs;
>> + return res;
>> +}
>> +
>> +/**
>> + * sg_copy_elem - copy one SG element to another
>> + * @dst_sg: destination SG element
>> + * @src_sg: source SG element
>> + * @copy_len: maximum amount of data to copy. If 0, then copy all.
>> + * @d_km_type: kmap_atomic type for the destination SG
>> + * @s_km_type: kmap_atomic type for the source SG
>> + *
>> + * Description:
>> + * Data from the source SG element will be copied to the destination SG
>> + * element. Returns number of bytes copied. Can switch to the next dst_sg
>> + * element, so, to copy to strictly only one dst_sg element, it must be
>> + * either last in the chain, or copy_len == dst_sg->length.
>> + */
>> +int sg_copy_elem(struct scatterlist *dst_sg, struct scatterlist *src_sg,
>> + size_t copy_len, enum km_type d_km_type,
>> + enum km_type s_km_type)
>> +{
>> + size_t dst_len = dst_sg->length, dst_offs = dst_sg->offset;
>> +
>> + return __sg_copy_elem(&dst_sg, &dst_len, &dst_offs, src_sg,
>> + copy_len, d_km_type, s_km_type);
>> +}
>> +EXPORT_SYMBOL(sg_copy_elem);
>
> Is not sg_copy_elem a copy of an sg with one element. Why do we need
> two exports.
>
> I would pass a nents count to below and discard this one.
>
>> +
>> +/**
>> + * sg_copy - copy one SG vector to another
>> + * @dst_sg: destination SG
>> + * @src_sg: source SG
>> + * @copy_len: maximum amount of data to copy. If 0, then copy all.
>> + * @d_km_type: kmap_atomic type for the destination SG
>> + * @s_km_type: kmap_atomic type for the source SG
>> + *
>> + * Description:
>> + * Data from the source SG vector will be copied to the destination SG
>> + * vector. End of the vectors will be determined by sg_next() returning
>> + * NULL. Returns number of bytes copied.
>> + */
>> +int sg_copy(struct scatterlist *dst_sg,
>> + struct scatterlist *src_sg, size_t copy_len,
>
> Total length is nice, but also a nents count
>
>> + enum km_type d_km_type, enum km_type s_km_type)
>> +{
>> + int res = 0;
>> + size_t dst_len, dst_offs;
>> +
>> + if (copy_len == 0)
>> + copy_len = 0x7FFFFFFF; /* copy all */
>> +
>> + dst_len = dst_sg->length;
>> + dst_offs = dst_sg->offset;
>> +
>> + do {
>> + copy_len -= __sg_copy_elem(&dst_sg, &dst_len, &dst_offs,
>> + src_sg, copy_len, d_km_type, s_km_type);
>> + if ((copy_len == 0) || (dst_sg == NULL))
>> + goto out;
>> +
>> + src_sg = sg_next(src_sg);
>> + } while (src_sg != NULL);
>> +
>> +out:
>> + return res;
>> +}
The return value res is always 0 here, contrary to the description.
Maybe it should be void.
>> +EXPORT_SYMBOL(sg_copy);
>>
>
> Boaz
--
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