sg: convert the indirect IO path to use the block layer (10db10d1) · Commits · 戴 / test

drivers/scsi/sg.c

+105 −292

Original line number	Diff line number	Diff line
		@@ -47,7 +47,6 @@ static int sg_version_num = 30534; /* 2 digits for each component */
		#include <linux/seq_file.h>
		#include <linux/blkdev.h>
		#include <linux/delay.h>
		#include <linux/scatterlist.h>
		#include <linux/blktrace_api.h>
		#include <linux/smp_lock.h>

		@@ -119,7 +118,8 @@ typedef struct sg_scatter_hold { /* holding area for scsi scatter gather info */
		unsigned sglist_len; /* size of malloc'd scatter-gather list ++ */
		unsigned bufflen; /* Size of (aggregate) data buffer */
		unsigned b_malloc_len; /* actual len malloc'ed in buffer */
		struct scatterlist buffer;/ scatter list */
		struct page **pages;
		int page_order;
		char dio_in_use; /* 0->indirect IO (or mmap), 1->dio */
		unsigned char cmd_opcode; /* first byte of command */
		} Sg_scatter_hold;
		@@ -190,8 +190,6 @@ static ssize_t sg_new_write(Sg_fd sfp, struct file file,
		int read_only, Sg_request **o_srp);
		static int sg_common_write(Sg_fd * sfp, Sg_request * srp,
		unsigned char *cmnd, int timeout, int blocking);
		static int sg_u_iovec(sg_io_hdr_t * hp, int sg_num, int ind,
		int wr_xf, int countp, unsigned char __user *up);
		static int sg_write_xfer(Sg_request * srp);
		static int sg_read_xfer(Sg_request * srp);
		static int sg_read_oxfer(Sg_request * srp, char __user *outp, int num_read_xfer);
		@@ -199,8 +197,6 @@ static void sg_remove_scat(Sg_scatter_hold * schp);
		static void sg_build_reserve(Sg_fd * sfp, int req_size);
		static void sg_link_reserve(Sg_fd * sfp, Sg_request * srp, int size);
		static void sg_unlink_reserve(Sg_fd * sfp, Sg_request * srp);
		static struct page sg_page_malloc(int rqSz, int lowDma, int retSzp);
		static void sg_page_free(struct page *page, int size);
		static Sg_fd sg_add_sfp(Sg_device sdp, int dev);
		static int sg_remove_sfp(Sg_device * sdp, Sg_fd * sfp);
		static void __sg_remove_sfp(Sg_device * sdp, Sg_fd * sfp);
		@@ -771,27 +767,12 @@ sg_common_write(Sg_fd * sfp, Sg_request * srp,
		break;
		}
		hp->duration = jiffies_to_msecs(jiffies);
		/* Now send everything of to mid-level. The next time we hear about this
		packet is when sg_cmd_done() is called (i.e. a callback). */
		if (srp->rq) {

		srp->rq->timeout = timeout;
		blk_execute_rq_nowait(sdp->device->request_queue, sdp->disk,
		srp->rq, 1, sg_rq_end_io);
		return 0;
		}
		if (scsi_execute_async(sdp->device, cmnd, hp->cmd_len, data_dir, srp->data.buffer,
		hp->dxfer_len, srp->data.k_use_sg, timeout,
		SG_DEFAULT_RETRIES, srp, sg_cmd_done,
		GFP_ATOMIC)) {
		SCSI_LOG_TIMEOUT(1, printk("sg_common_write: scsi_execute_async failed\n"));
		/*
		* most likely out of mem, but could also be a bad map
		*/
		sg_finish_rem_req(srp);
		return -ENOMEM;
		} else
		return 0;
		}

		static int
		sg_srp_done(Sg_request srp, Sg_fd sfp)
		@@ -1206,8 +1187,7 @@ sg_vma_fault(struct vm_area_struct vma, struct vm_fault vmf)
		Sg_fd *sfp;
		unsigned long offset, len, sa;
		Sg_scatter_hold *rsv_schp;
		struct scatterlist *sg;
		int k;
		int k, length;

		if ((NULL == vma) \|\| (!(sfp = (Sg_fd *) vma->vm_private_data)))
		return VM_FAULT_SIGBUS;
		@@ -1217,15 +1197,14 @@ sg_vma_fault(struct vm_area_struct vma, struct vm_fault vmf)
		return VM_FAULT_SIGBUS;
		SCSI_LOG_TIMEOUT(3, printk("sg_vma_fault: offset=%lu, scatg=%d\n",
		offset, rsv_schp->k_use_sg));
		sg = rsv_schp->buffer;
		sa = vma->vm_start;
		for (k = 0; (k < rsv_schp->k_use_sg) && (sa < vma->vm_end);
		++k, sg = sg_next(sg)) {
		length = 1 << (PAGE_SHIFT + rsv_schp->page_order);
		for (k = 0; k < rsv_schp->k_use_sg && sa < vma->vm_end; k++) {
		len = vma->vm_end - sa;
		len = (len < sg->length) ? len : sg->length;
		len = (len < length) ? len : length;
		if (offset < len) {
		struct page *page;
		page = virt_to_page(page_address(sg_page(sg)) + offset);
		struct page *page = nth_page(rsv_schp->pages[k],
		offset >> PAGE_SHIFT);
		get_page(page); /* increment page count */
		vmf->page = page;
		return 0; /* success */
		@@ -1247,8 +1226,7 @@ sg_mmap(struct file filp, struct vm_area_struct vma)
		Sg_fd *sfp;
		unsigned long req_sz, len, sa;
		Sg_scatter_hold *rsv_schp;
		int k;
		struct scatterlist *sg;
		int k, length;

		if ((!filp) \|\| (!vma) \|\| (!(sfp = (Sg_fd *) filp->private_data)))
		return -ENXIO;
		@@ -1262,11 +1240,10 @@ sg_mmap(struct file filp, struct vm_area_struct vma)
		return -ENOMEM; /* cannot map more than reserved buffer */

		sa = vma->vm_start;
		sg = rsv_schp->buffer;
		for (k = 0; (k < rsv_schp->k_use_sg) && (sa < vma->vm_end);
		++k, sg = sg_next(sg)) {
		length = 1 << (PAGE_SHIFT + rsv_schp->page_order);
		for (k = 0; k < rsv_schp->k_use_sg && sa < vma->vm_end; k++) {
		len = vma->vm_end - sa;
		len = (len < sg->length) ? len : sg->length;
		len = (len < length) ? len : length;
		sa += len;
		}

		@@ -1310,7 +1287,6 @@ sg_cmd_done(void data, char sense, int result, int resid)
		if (0 != result) {
		struct scsi_sense_hdr sshdr;

		memcpy(srp->sense_b, sense, sizeof (srp->sense_b));
		srp->header.status = 0xff & result;
		srp->header.masked_status = status_byte(result);
		srp->header.msg_status = msg_byte(result);
		@@ -1685,34 +1661,51 @@ static int sg_start_req(Sg_request srp, unsigned char cmd)
		Sg_scatter_hold *rsv_schp = &sfp->reserve;
		struct request_queue *q = sfp->parentdp->device->request_queue;
		unsigned long alignment = queue_dma_alignment(q) \| q->dma_pad_mask;
		struct rq_map_data map_data;

		SCSI_LOG_TIMEOUT(4, printk("sg_start_req: dxfer_len=%d\n", dxfer_len));

		res = __sg_start_req(srp, hp, cmd);
		if (res)
		return res;

		if ((dxfer_len <= 0) \|\| (dxfer_dir == SG_DXFER_NONE))
		return __sg_start_req(srp, hp, cmd);
		return 0;

		#ifdef SG_ALLOW_DIO_CODE
		if (sg_allow_dio && (hp->flags & SG_FLAG_DIRECT_IO) &&
		(dxfer_dir != SG_DXFER_UNKNOWN) && (0 == hp->iovec_count) &&
		(!sfp->parentdp->device->host->unchecked_isa_dma) &&
		!(uaddr & alignment) && !(dxfer_len & alignment)) {
		res = __sg_start_req(srp, hp, cmd);
		if (!res)
		res = sg_build_direct(srp, sfp, dxfer_len);

		return res;
		}
		!(uaddr & alignment) && !(dxfer_len & alignment))
		return sg_build_direct(srp, sfp, dxfer_len);
		#endif
		if ((!sg_res_in_use(sfp)) && (dxfer_len <= rsv_schp->bufflen))
		sg_link_reserve(sfp, srp, dxfer_len);
		else {
		else
		res = sg_build_indirect(req_schp, sfp, dxfer_len);
		if (res) {
		sg_remove_scat(req_schp);
		return res;
		}

		if (!res) {
		struct request *rq = srp->rq;
		Sg_scatter_hold *schp = &srp->data;
		int iovec_count = (int) hp->iovec_count;

		map_data.pages = schp->pages;
		map_data.page_order = schp->page_order;
		map_data.nr_entries = schp->k_use_sg;

		if (iovec_count)
		res = blk_rq_map_user_iov(q, rq, &map_data, hp->dxferp,
		iovec_count,
		hp->dxfer_len, GFP_ATOMIC);
		else
		res = blk_rq_map_user(q, rq, &map_data, hp->dxferp,
		hp->dxfer_len, GFP_ATOMIC);

		if (!res)
		srp->bio = rq->bio;
		}
		return 0;

		return res;
		}

		static void
		@@ -1730,6 +1723,7 @@ sg_finish_rem_req(Sg_request * srp)
		if (srp->rq) {
		if (srp->bio)
		blk_rq_unmap_user(srp->bio);

		blk_put_request(srp->rq);
		}

		@@ -1739,21 +1733,12 @@ sg_finish_rem_req(Sg_request * srp)
		static int
		sg_build_sgat(Sg_scatter_hold * schp, const Sg_fd * sfp, int tablesize)
		{
		int sg_bufflen = tablesize * sizeof(struct scatterlist);
		int sg_bufflen = tablesize * sizeof(struct page *);
		gfp_t gfp_flags = GFP_ATOMIC \| __GFP_NOWARN;

		/*
		* TODO: test without low_dma, we should not need it since
		* the block layer will bounce the buffer for us
		*
		* XXX(hch): we shouldn't need GFP_DMA for the actual S/G list.
		*/
		if (sfp->low_dma)
		gfp_flags \|= GFP_DMA;
		schp->buffer = kzalloc(sg_bufflen, gfp_flags);
		if (!schp->buffer)
		schp->pages = kzalloc(sg_bufflen, gfp_flags);
		if (!schp->pages)
		return -ENOMEM;
		sg_init_table(schp->buffer, tablesize);
		schp->sglist_len = sg_bufflen;
		return tablesize; /* number of scat_gath elements allocated */
		}
		@@ -1780,11 +1765,10 @@ sg_build_direct(Sg_request * srp, Sg_fd * sfp, int dxfer_len)
		static int
		sg_build_indirect(Sg_scatter_hold * schp, Sg_fd * sfp, int buff_size)
		{
		struct scatterlist *sg;
		int ret_sz = 0, k, rem_sz, num, mx_sc_elems;
		int ret_sz = 0, i, k, rem_sz, num, mx_sc_elems;
		int sg_tablesize = sfp->parentdp->sg_tablesize;
		int blk_size = buff_size;
		struct page *p = NULL;
		int blk_size = buff_size, order;
		gfp_t gfp_mask = GFP_ATOMIC \| __GFP_COMP \| __GFP_NOWARN;

		if (blk_size < 0)
		return -EFAULT;
		@@ -1808,15 +1792,26 @@ sg_build_indirect(Sg_scatter_hold * schp, Sg_fd * sfp, int buff_size)
		} else
		scatter_elem_sz_prev = num;
		}
		for (k = 0, sg = schp->buffer, rem_sz = blk_size;
		(rem_sz > 0) && (k < mx_sc_elems);
		++k, rem_sz -= ret_sz, sg = sg_next(sg)) {

		if (sfp->low_dma)
		gfp_mask \|= GFP_DMA;

		if (!capable(CAP_SYS_ADMIN) \|\| !capable(CAP_SYS_RAWIO))
		gfp_mask \|= __GFP_ZERO;

		order = get_order(num);
		retry:
		ret_sz = 1 << (PAGE_SHIFT + order);

		for (k = 0, rem_sz = blk_size; rem_sz > 0 && k < mx_sc_elems;
		k++, rem_sz -= ret_sz) {

		num = (rem_sz > scatter_elem_sz_prev) ?
		scatter_elem_sz_prev : rem_sz;
		p = sg_page_malloc(num, sfp->low_dma, &ret_sz);
		if (!p)
		return -ENOMEM;

		schp->pages[k] = alloc_pages(gfp_mask, order);
		if (!schp->pages[k])
		goto out;

		if (num == scatter_elem_sz_prev) {
		if (unlikely(ret_sz > scatter_elem_sz_prev)) {
		@@ -1824,12 +1819,12 @@ sg_build_indirect(Sg_scatter_hold * schp, Sg_fd * sfp, int buff_size)
		scatter_elem_sz_prev = ret_sz;
		}
		}
		sg_set_page(sg, p, (ret_sz > num) ? num : ret_sz, 0);

		SCSI_LOG_TIMEOUT(5, printk("sg_build_indirect: k=%d, num=%d, "
		"ret_sz=%d\n", k, num, ret_sz));
		} /* end of for loop */

		schp->page_order = order;
		schp->k_use_sg = k;
		SCSI_LOG_TIMEOUT(5, printk("sg_build_indirect: k_use_sg=%d, "
		"rem_sz=%d\n", k, rem_sz));
		@@ -1837,8 +1832,15 @@ sg_build_indirect(Sg_scatter_hold * schp, Sg_fd * sfp, int buff_size)
		schp->bufflen = blk_size;
		if (rem_sz > 0) /* must have failed */
		return -ENOMEM;

		return 0;
		out:
		for (i = 0; i < k; i++)
		__free_pages(schp->pages[k], order);

		if (--order >= 0)
		goto retry;

		return -ENOMEM;
		}

		static int
		@@ -1846,13 +1848,8 @@ sg_write_xfer(Sg_request * srp)
		{
		sg_io_hdr_t *hp = &srp->header;
		Sg_scatter_hold *schp = &srp->data;
		struct scatterlist *sg = schp->buffer;
		int num_xfer = 0;
		int j, k, onum, usglen, ksglen, res;
		int iovec_count = (int) hp->iovec_count;
		int dxfer_dir = hp->dxfer_direction;
		unsigned char *p;
		unsigned char __user *up;
		int new_interface = ('\0' == hp->interface_id) ? 0 : 1;

		if ((SG_DXFER_UNKNOWN == dxfer_dir) \|\| (SG_DXFER_TO_DEV == dxfer_dir) \|\|
		@@ -1866,83 +1863,9 @@ sg_write_xfer(Sg_request * srp)
		&& ((SG_FLAG_NO_DXFER \| SG_FLAG_MMAP_IO) & hp->flags)))
		return 0;

		SCSI_LOG_TIMEOUT(4, printk("sg_write_xfer: num_xfer=%d, iovec_count=%d, k_use_sg=%d\n",
		num_xfer, iovec_count, schp->k_use_sg));
		if (iovec_count) {
		onum = iovec_count;
		if (!access_ok(VERIFY_READ, hp->dxferp, SZ_SG_IOVEC * onum))
		return -EFAULT;
		} else
		onum = 1;

		ksglen = sg->length;
		p = page_address(sg_page(sg));
		for (j = 0, k = 0; j < onum; ++j) {
		res = sg_u_iovec(hp, iovec_count, j, 1, &usglen, &up);
		if (res)
		return res;

		for (; p; sg = sg_next(sg), ksglen = sg->length,
		p = page_address(sg_page(sg))) {
		if (usglen <= 0)
		break;
		if (ksglen > usglen) {
		if (usglen >= num_xfer) {
		if (__copy_from_user(p, up, num_xfer))
		return -EFAULT;
		return 0;
		}
		if (__copy_from_user(p, up, usglen))
		return -EFAULT;
		p += usglen;
		ksglen -= usglen;
		break;
		} else {
		if (ksglen >= num_xfer) {
		if (__copy_from_user(p, up, num_xfer))
		return -EFAULT;
		return 0;
		}
		if (__copy_from_user(p, up, ksglen))
		return -EFAULT;
		up += ksglen;
		usglen -= ksglen;
		}
		++k;
		if (k >= schp->k_use_sg)
		return 0;
		}
		}

		return 0;
		}
		SCSI_LOG_TIMEOUT(4, printk("sg_write_xfer: num_xfer=%d, k_use_sg=%d\n",
		num_xfer, schp->k_use_sg));

		static int
		sg_u_iovec(sg_io_hdr_t * hp, int sg_num, int ind,
		int wr_xf, int countp, unsigned char __user *up)
		{
		int num_xfer = (int) hp->dxfer_len;
		unsigned char __user *p = hp->dxferp;
		int count;

		if (0 == sg_num) {
		if (wr_xf && ('\0' == hp->interface_id))
		count = (int) hp->flags; /* holds "old" input_size */
		else
		count = num_xfer;
		} else {
		sg_iovec_t iovec;
		if (__copy_from_user(&iovec, p + ind*SZ_SG_IOVEC, SZ_SG_IOVEC))
		return -EFAULT;
		p = iovec.iov_base;
		count = (int) iovec.iov_len;
		}
		if (!access_ok(wr_xf ? VERIFY_READ : VERIFY_WRITE, p, count))
		return -EFAULT;
		if (up)
		*up = p;
		if (countp)
		*countp = count;
		return 0;
		}

		@@ -1950,21 +1873,18 @@ static void
		sg_remove_scat(Sg_scatter_hold * schp)
		{
		SCSI_LOG_TIMEOUT(4, printk("sg_remove_scat: k_use_sg=%d\n", schp->k_use_sg));
		if (schp->buffer && (schp->sglist_len > 0)) {
		struct scatterlist *sg = schp->buffer;

		if (schp->pages && schp->sglist_len > 0) {
		if (!schp->dio_in_use) {
		int k;

		for (k = 0; (k < schp->k_use_sg) && sg_page(sg);
		++k, sg = sg_next(sg)) {
		for (k = 0; k < schp->k_use_sg && schp->pages[k]; k++) {
		SCSI_LOG_TIMEOUT(5, printk(
		"sg_remove_scat: k=%d, pg=0x%p, len=%d\n",
		k, sg_page(sg), sg->length));
		sg_page_free(sg_page(sg), sg->length);
		"sg_remove_scat: k=%d, pg=0x%p\n",
		k, schp->pages[k]));
		__free_pages(schp->pages[k], schp->page_order);
		}

		kfree(schp->buffer);
		kfree(schp->pages);
		}
		}
		memset(schp, 0, sizeof (*schp));
		@@ -1975,13 +1895,8 @@ sg_read_xfer(Sg_request * srp)
		{
		sg_io_hdr_t *hp = &srp->header;
		Sg_scatter_hold *schp = &srp->data;
		struct scatterlist *sg = schp->buffer;
		int num_xfer = 0;
		int j, k, onum, usglen, ksglen, res;
		int iovec_count = (int) hp->iovec_count;
		int dxfer_dir = hp->dxfer_direction;
		unsigned char *p;
		unsigned char __user *up;
		int new_interface = ('\0' == hp->interface_id) ? 0 : 1;

		if ((SG_DXFER_UNKNOWN == dxfer_dir) \|\| (SG_DXFER_FROM_DEV == dxfer_dir)
		@@ -1996,53 +1911,7 @@ sg_read_xfer(Sg_request * srp)
		return 0;

		SCSI_LOG_TIMEOUT(4, printk("sg_read_xfer: num_xfer=%d, iovec_count=%d, k_use_sg=%d\n",
		num_xfer, iovec_count, schp->k_use_sg));
		if (iovec_count) {
		onum = iovec_count;
		if (!access_ok(VERIFY_READ, hp->dxferp, SZ_SG_IOVEC * onum))
		return -EFAULT;
		} else
		onum = 1;

		p = page_address(sg_page(sg));
		ksglen = sg->length;
		for (j = 0, k = 0; j < onum; ++j) {
		res = sg_u_iovec(hp, iovec_count, j, 0, &usglen, &up);
		if (res)
		return res;

		for (; p; sg = sg_next(sg), ksglen = sg->length,
		p = page_address(sg_page(sg))) {
		if (usglen <= 0)
		break;
		if (ksglen > usglen) {
		if (usglen >= num_xfer) {
		if (__copy_to_user(up, p, num_xfer))
		return -EFAULT;
		return 0;
		}
		if (__copy_to_user(up, p, usglen))
		return -EFAULT;
		p += usglen;
		ksglen -= usglen;
		break;
		} else {
		if (ksglen >= num_xfer) {
		if (__copy_to_user(up, p, num_xfer))
		return -EFAULT;
		return 0;
		}
		if (__copy_to_user(up, p, ksglen))
		return -EFAULT;
		up += ksglen;
		usglen -= ksglen;
		}
		++k;
		if (k >= schp->k_use_sg)
		return 0;
		}
		}

		num_xfer, (int)hp->iovec_count, schp->k_use_sg));
		return 0;
		}

		@@ -2050,7 +1919,6 @@ static int
		sg_read_oxfer(Sg_request * srp, char __user *outp, int num_read_xfer)
		{
		Sg_scatter_hold *schp = &srp->data;
		struct scatterlist *sg = schp->buffer;
		int k, num;

		SCSI_LOG_TIMEOUT(4, printk("sg_read_oxfer: num_read_xfer=%d\n",
		@@ -2058,15 +1926,18 @@ sg_read_oxfer(Sg_request * srp, char __user *outp, int num_read_xfer)
		if ((!outp) \|\| (num_read_xfer <= 0))
		return 0;

		for (k = 0; (k < schp->k_use_sg) && sg_page(sg); ++k, sg = sg_next(sg)) {
		num = sg->length;
		blk_rq_unmap_user(srp->bio);
		srp->bio = NULL;

		num = 1 << (PAGE_SHIFT + schp->page_order);
		for (k = 0; k < schp->k_use_sg && schp->pages[k]; k++) {
		if (num > num_read_xfer) {
		if (__copy_to_user(outp, page_address(sg_page(sg)),
		if (__copy_to_user(outp, page_address(schp->pages[k]),
		num_read_xfer))
		return -EFAULT;
		break;
		} else {
		if (__copy_to_user(outp, page_address(sg_page(sg)),
		if (__copy_to_user(outp, page_address(schp->pages[k]),
		num))
		return -EFAULT;
		num_read_xfer -= num;
		@@ -2101,24 +1972,22 @@ sg_link_reserve(Sg_fd * sfp, Sg_request * srp, int size)
		{
		Sg_scatter_hold *req_schp = &srp->data;
		Sg_scatter_hold *rsv_schp = &sfp->reserve;
		struct scatterlist *sg = rsv_schp->buffer;
		int k, num, rem;

		srp->res_used = 1;
		SCSI_LOG_TIMEOUT(4, printk("sg_link_reserve: size=%d\n", size));
		rem = size;

		for (k = 0; k < rsv_schp->k_use_sg; ++k, sg = sg_next(sg)) {
		num = sg->length;
		num = 1 << (PAGE_SHIFT + rsv_schp->page_order);
		for (k = 0; k < rsv_schp->k_use_sg; k++) {
		if (rem <= num) {
		sfp->save_scat_len = num;
		sg->length = rem;
		req_schp->k_use_sg = k + 1;
		req_schp->sglist_len = rsv_schp->sglist_len;
		req_schp->buffer = rsv_schp->buffer;
		req_schp->pages = rsv_schp->pages;

		req_schp->bufflen = size;
		req_schp->b_malloc_len = rsv_schp->b_malloc_len;
		req_schp->page_order = rsv_schp->page_order;
		break;
		} else
		rem -= num;
		@@ -2132,22 +2001,13 @@ static void
		sg_unlink_reserve(Sg_fd * sfp, Sg_request * srp)
		{
		Sg_scatter_hold *req_schp = &srp->data;
		Sg_scatter_hold *rsv_schp = &sfp->reserve;

		SCSI_LOG_TIMEOUT(4, printk("sg_unlink_reserve: req->k_use_sg=%d\n",
		(int) req_schp->k_use_sg));
		if ((rsv_schp->k_use_sg > 0) && (req_schp->k_use_sg > 0)) {
		struct scatterlist *sg = rsv_schp->buffer;

		if (sfp->save_scat_len > 0)
		(sg + (req_schp->k_use_sg - 1))->length =
		(unsigned) sfp->save_scat_len;
		else
		SCSI_LOG_TIMEOUT(1, printk ("sg_unlink_reserve: BAD save_scat_len\n"));
		}
		req_schp->k_use_sg = 0;
		req_schp->bufflen = 0;
		req_schp->buffer = NULL;
		req_schp->pages = NULL;
		req_schp->page_order = 0;
		req_schp->sglist_len = 0;
		sfp->save_scat_len = 0;
		srp->res_used = 0;
		@@ -2405,53 +2265,6 @@ sg_res_in_use(Sg_fd * sfp)
		return srp ? 1 : 0;
		}

		/* The size fetched (value output via retSzp) set when non-NULL return */
		static struct page *
		sg_page_malloc(int rqSz, int lowDma, int *retSzp)
		{
		struct page *resp = NULL;
		gfp_t page_mask;
		int order, a_size;
		int resSz;

		if ((rqSz <= 0) \|\| (NULL == retSzp))
		return resp;

		if (lowDma)
		page_mask = GFP_ATOMIC \| GFP_DMA \| __GFP_COMP \| __GFP_NOWARN;
		else
		page_mask = GFP_ATOMIC \| __GFP_COMP \| __GFP_NOWARN;

		for (order = 0, a_size = PAGE_SIZE; a_size < rqSz;
		order++, a_size <<= 1) ;
		resSz = a_size; /* rounded up if necessary */
		resp = alloc_pages(page_mask, order);
		while ((!resp) && order) {
		--order;
		a_size >>= 1; /* divide by 2, until PAGE_SIZE */
		resp = alloc_pages(page_mask, order); /* try half */
		resSz = a_size;
		}
		if (resp) {
		if (!capable(CAP_SYS_ADMIN) \|\| !capable(CAP_SYS_RAWIO))
		memset(page_address(resp), 0, resSz);
		*retSzp = resSz;
		}
		return resp;
		}

		static void
		sg_page_free(struct page *page, int size)
		{
		int order, a_size;

		if (!page)
		return;
		for (order = 0, a_size = PAGE_SIZE; a_size < size;
		order++, a_size <<= 1) ;
		__free_pages(page, order);
		}

		#ifdef CONFIG_SCSI_PROC_FS
		static int
		sg_idr_max_id(int id, void p, void data)

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