Merge branch 'for-2.6.28' of git://git.kernel.dk/linux-2.6-block

* 'for-2.6.28' of git://git.kernel.dk/linux-2.6-block: (132 commits)
  doc/cdrom: Trvial documentation error, file not present
  block_dev: fix kernel-doc in new functions
  block: add some comments around the bio read-write flags
  block: mark bio_split_pool static
  block: Find bio sector offset given idx and offset
  block: gendisk integrity wrapper
  block: Switch blk_integrity_compare from bdev to gendisk
  block: Fix double put in blk_integrity_unregister
  block: Introduce integrity data ownership flag
  block: revert part of d7533ad0e132f92e75c1b2eb7c26387b25a583c1
  bio.h: Remove unused conditional code
  block: remove end_{queued|dequeued}_request()
  block: change elevator to use __blk_end_request()
  gdrom: change to use __blk_end_request()
  memstick: change to use __blk_end_request()
  virtio_blk: change to use __blk_end_request()
  blktrace: use BLKTRACE_BDEV_SIZE as the name size for setup structure
  block: add lld busy state exporting interface
  block: Fix blk_start_queueing() to not kick a stopped queue
  include blktrace_api.h in headers_install
  ...

1 files changed, 157 insertions, 510 deletions

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 661f9f21650..ba9b9bbd4e7 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -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>
 
@@ -69,7 +68,6 @@ static void sg_proc_cleanup(void);
 #endif
 
 #define SG_ALLOW_DIO_DEF 0
-#define SG_ALLOW_DIO_CODE /* compile out by commenting this define */
 
 #define SG_MAX_DEVS 32768
 
@@ -118,8 +116,8 @@ typedef struct sg_scatter_hold { /* holding area for scsi scatter gather info */
 	unsigned short k_use_sg; /* Count of kernel scatter-gather pieces */
 	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;
@@ -137,6 +135,8 @@ typedef struct sg_request {	/* SG_MAX_QUEUE requests outstanding per file */
 	char orphan;		/* 1 -> drop on sight, 0 -> normal */
 	char sg_io_owned;	/* 1 -> packet belongs to SG_IO */
 	volatile char done;	/* 0->before bh, 1->before read, 2->read */
+	struct request *rq;
+	struct bio *bio;
 } Sg_request;
 
 typedef struct sg_fd {		/* holds the state of a file descriptor */
@@ -175,8 +175,8 @@ typedef struct sg_device { /* holds the state of each scsi generic device */
 
 static int sg_fasync(int fd, struct file *filp, int mode);
 /* tasklet or soft irq callback */
-static void sg_cmd_done(void *data, char *sense, int result, int resid);
-static int sg_start_req(Sg_request * srp);
+static void sg_rq_end_io(struct request *rq, int uptodate);
+static int sg_start_req(Sg_request *srp, unsigned char *cmd);
 static void sg_finish_rem_req(Sg_request * srp);
 static int sg_build_indirect(Sg_scatter_hold * schp, Sg_fd * sfp, int buff_size);
 static int sg_build_sgat(Sg_scatter_hold * schp, const Sg_fd * sfp,
@@ -188,17 +188,11 @@ 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);
 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);
@@ -206,7 +200,6 @@ static Sg_request *sg_get_rq_mark(Sg_fd * sfp, int pack_id);
 static Sg_request *sg_add_request(Sg_fd * sfp);
 static int sg_remove_request(Sg_fd * sfp, Sg_request * srp);
 static int sg_res_in_use(Sg_fd * sfp);
-static int sg_build_direct(Sg_request * srp, Sg_fd * sfp, int dxfer_len);
 static Sg_device *sg_get_dev(int dev);
 #ifdef CONFIG_SCSI_PROC_FS
 static int sg_last_dev(void);
@@ -529,8 +522,7 @@ sg_new_read(Sg_fd * sfp, char __user *buf, size_t count, Sg_request * srp)
 		err = -EFAULT;
 		goto err_out;
 	}
-	err = sg_read_xfer(srp);
-      err_out:
+err_out:
 	sg_finish_rem_req(srp);
 	return (0 == err) ? count : err;
 }
@@ -612,7 +604,10 @@ sg_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
 	else
 		hp->dxfer_direction = (mxsize > 0) ? SG_DXFER_FROM_DEV : SG_DXFER_NONE;
 	hp->dxfer_len = mxsize;
-	hp->dxferp = (char __user *)buf + cmd_size;
+	if (hp->dxfer_direction == SG_DXFER_TO_DEV)
+		hp->dxferp = (char __user *)buf + cmd_size;
+	else
+		hp->dxferp = NULL;
 	hp->sbp = NULL;
 	hp->timeout = old_hdr.reply_len;	/* structure abuse ... */
 	hp->flags = input_size;	/* structure abuse ... */
@@ -732,16 +727,12 @@ sg_common_write(Sg_fd * sfp, Sg_request * srp,
 	SCSI_LOG_TIMEOUT(4, printk("sg_common_write:  scsi opcode=0x%02x, cmd_size=%d\n",
 			  (int) cmnd[0], (int) hp->cmd_len));
 
-	if ((k = sg_start_req(srp))) {
+	k = sg_start_req(srp, cmnd);
+	if (k) {
 		SCSI_LOG_TIMEOUT(1, printk("sg_common_write: start_req err=%d\n", k));
 		sg_finish_rem_req(srp);
 		return k;	/* probably out of space --> ENOMEM */
 	}
-	if ((k = sg_write_xfer(srp))) {
-		SCSI_LOG_TIMEOUT(1, printk("sg_common_write: write_xfer, bad address\n"));
-		sg_finish_rem_req(srp);
-		return k;
-	}
 	if (sdp->detached) {
 		sg_finish_rem_req(srp);
 		return -ENODEV;
@@ -763,20 +754,11 @@ 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 (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;
+
+	srp->rq->timeout = timeout;
+	blk_execute_rq_nowait(sdp->device->request_queue, sdp->disk,
+			      srp->rq, 1, sg_rq_end_io);
+	return 0;
 }
 
 static int
@@ -1192,8 +1174,7 @@ 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;
@@ -1203,15 +1184,14 @@ 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 */
@@ -1233,8 +1213,7 @@ 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;
@@ -1248,11 +1227,10 @@ 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;
 	}
 
@@ -1263,16 +1241,19 @@ sg_mmap(struct file *filp, struct vm_area_struct *vma)
 	return 0;
 }
 
-/* This function is a "bottom half" handler that is called by the
- * mid level when a command is completed (or has failed). */
-static void
-sg_cmd_done(void *data, char *sense, int result, int resid)
+/*
+ * This function is a "bottom half" handler that is called by the mid
+ * level when a command is completed (or has failed).
+ */
+static void sg_rq_end_io(struct request *rq, int uptodate)
 {
-	Sg_request *srp = data;
+	struct sg_request *srp = rq->end_io_data;
 	Sg_device *sdp = NULL;
 	Sg_fd *sfp;
 	unsigned long iflags;
 	unsigned int ms;
+	char *sense;
+	int result, resid;
 
 	if (NULL == srp) {
 		printk(KERN_ERR "sg_cmd_done: NULL request\n");
@@ -1286,6 +1267,9 @@ sg_cmd_done(void *data, char *sense, int result, int resid)
 		return;
 	}
 
+	sense = rq->sense;
+	result = rq->errors;
+	resid = rq->data_len;
 
 	SCSI_LOG_TIMEOUT(4, printk("sg_cmd_done: %s, pack_id=%d, res=0x%x\n",
 		sdp->disk->disk_name, srp->header.pack_id, result));
@@ -1296,7 +1280,6 @@ 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);
@@ -1634,37 +1617,79 @@ exit_sg(void)
 	idr_destroy(&sg_index_idr);
 }
 
-static int
-sg_start_req(Sg_request * srp)
+static int sg_start_req(Sg_request *srp, unsigned char *cmd)
 {
 	int res;
+	struct request *rq;
 	Sg_fd *sfp = srp->parentfp;
 	sg_io_hdr_t *hp = &srp->header;
 	int dxfer_len = (int) hp->dxfer_len;
 	int dxfer_dir = hp->dxfer_direction;
+	unsigned int iov_count = hp->iovec_count;
 	Sg_scatter_hold *req_schp = &srp->data;
 	Sg_scatter_hold *rsv_schp = &sfp->reserve;
+	struct request_queue *q = sfp->parentdp->device->request_queue;
+	struct rq_map_data *md, map_data;
+	int rw = hp->dxfer_direction == SG_DXFER_TO_DEV ? WRITE : READ;
+
+	SCSI_LOG_TIMEOUT(4, printk(KERN_INFO "sg_start_req: dxfer_len=%d\n",
+				   dxfer_len));
+
+	rq = blk_get_request(q, rw, GFP_ATOMIC);
+	if (!rq)
+		return -ENOMEM;
+
+	memcpy(rq->cmd, cmd, hp->cmd_len);
+
+	rq->cmd_len = hp->cmd_len;
+	rq->cmd_type = REQ_TYPE_BLOCK_PC;
+
+	srp->rq = rq;
+	rq->end_io_data = srp;
+	rq->sense = srp->sense_b;
+	rq->retries = SG_DEFAULT_RETRIES;
 
-	SCSI_LOG_TIMEOUT(4, printk("sg_start_req: dxfer_len=%d\n", dxfer_len));
 	if ((dxfer_len <= 0) || (dxfer_dir == SG_DXFER_NONE))
 		return 0;
-	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)) {
-		res = sg_build_direct(srp, sfp, dxfer_len);
-		if (res <= 0)	/* -ve -> error, 0 -> done, 1 -> try indirect */
-			return res;
-	}
-	if ((!sg_res_in_use(sfp)) && (dxfer_len <= rsv_schp->bufflen))
-		sg_link_reserve(sfp, srp, dxfer_len);
-	else {
-		res = sg_build_indirect(req_schp, sfp, dxfer_len);
-		if (res) {
-			sg_remove_scat(req_schp);
-			return res;
+
+	if (sg_allow_dio && hp->flags & SG_FLAG_DIRECT_IO &&
+	    dxfer_dir != SG_DXFER_UNKNOWN && !iov_count &&
+	    !sfp->parentdp->device->host->unchecked_isa_dma &&
+	    blk_rq_aligned(q, hp->dxferp, dxfer_len))
+		md = NULL;
+	else
+		md = &map_data;
+
+	if (md) {
+		if (!sg_res_in_use(sfp) && dxfer_len <= rsv_schp->bufflen)
+			sg_link_reserve(sfp, srp, dxfer_len);
+		else {
+			res = sg_build_indirect(req_schp, sfp, dxfer_len);
+			if (res)
+				return res;
 		}
+
+		md->pages = req_schp->pages;
+		md->page_order = req_schp->page_order;
+		md->nr_entries = req_schp->k_use_sg;
 	}
-	return 0;
+
+	if (iov_count)
+		res = blk_rq_map_user_iov(q, rq, md, hp->dxferp, iov_count,
+					  hp->dxfer_len, GFP_ATOMIC);
+	else
+		res = blk_rq_map_user(q, rq, md, hp->dxferp,
+				      hp->dxfer_len, GFP_ATOMIC);
+
+	if (!res) {
+		srp->bio = rq->bio;
+
+		if (!md) {
+			req_schp->dio_in_use = 1;
+			hp->info |= SG_INFO_DIRECT_IO;
+		}
+	}
+	return res;
 }
 
 static void
@@ -1678,186 +1703,37 @@ sg_finish_rem_req(Sg_request * srp)
 		sg_unlink_reserve(sfp, srp);
 	else
 		sg_remove_scat(req_schp);
+
+	if (srp->rq) {
+		if (srp->bio)
+			blk_rq_unmap_user(srp->bio);
+
+		blk_put_request(srp->rq);
+	}
+
 	sg_remove_request(sfp, 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 */
 }
 
-#ifdef SG_ALLOW_DIO_CODE
-/* vvvvvvvv  following code borrowed from st driver's direct IO vvvvvvvvv */
-	/* TODO: hopefully we can use the generic block layer code */
-
-/* Pin down user pages and put them into a scatter gather list. Returns <= 0 if
-   - mapping of all pages not successful
-   (i.e., either completely successful or fails)
-*/
-static int 
-st_map_user_pages(struct scatterlist *sgl, const unsigned int max_pages, 
-	          unsigned long uaddr, size_t count, int rw)
-{
-	unsigned long end = (uaddr + count + PAGE_SIZE - 1) >> PAGE_SHIFT;
-	unsigned long start = uaddr >> PAGE_SHIFT;
-	const int nr_pages = end - start;
-	int res, i, j;
-	struct page **pages;
-
-	/* User attempted Overflow! */
-	if ((uaddr + count) < uaddr)
-		return -EINVAL;
-
-	/* Too big */
-        if (nr_pages > max_pages)
-		return -ENOMEM;
-
-	/* Hmm? */
-	if (count == 0)
-		return 0;
-
-	if ((pages = kmalloc(max_pages * sizeof(*pages), GFP_ATOMIC)) == NULL)
-		return -ENOMEM;
-
-        /* Try to fault in all of the necessary pages */
-	down_read(&current->mm->mmap_sem);
-        /* rw==READ means read from drive, write into memory area */
-	res = get_user_pages(
-		current,
-		current->mm,
-		uaddr,
-		nr_pages,
-		rw == READ,
-		0, /* don't force */
-		pages,
-		NULL);
-	up_read(&current->mm->mmap_sem);
-
-	/* Errors and no page mapped should return here */
-	if (res < nr_pages)
-		goto out_unmap;
-
-        for (i=0; i < nr_pages; i++) {
-                /* FIXME: flush superflous for rw==READ,
-                 * probably wrong function for rw==WRITE
-                 */
-		flush_dcache_page(pages[i]);
-		/* ?? Is locking needed? I don't think so */
-		/* if (!trylock_page(pages[i]))
-		   goto out_unlock; */
-        }
-
-	sg_set_page(sgl, pages[0], 0, uaddr & ~PAGE_MASK);
-	if (nr_pages > 1) {
-		sgl[0].length = PAGE_SIZE - sgl[0].offset;
-		count -= sgl[0].length;
-		for (i=1; i < nr_pages ; i++)
-			sg_set_page(&sgl[i], pages[i], count < PAGE_SIZE ? count : PAGE_SIZE, 0);
-	}
-	else {
-		sgl[0].length = count;
-	}
-
-	kfree(pages);
-	return nr_pages;
-
- out_unmap:
-	if (res > 0) {
-		for (j=0; j < res; j++)
-			page_cache_release(pages[j]);
-		res = 0;
-	}
-	kfree(pages);
-	return res;
-}
-
-
-/* And unmap them... */
-static int 
-st_unmap_user_pages(struct scatterlist *sgl, const unsigned int nr_pages,
-		    int dirtied)
-{
-	int i;
-
-	for (i=0; i < nr_pages; i++) {
-		struct page *page = sg_page(&sgl[i]);
-
-		if (dirtied)
-			SetPageDirty(page);
-		/* unlock_page(page); */
-		/* FIXME: cache flush missing for rw==READ
-		 * FIXME: call the correct reference counting function
-		 */
-		page_cache_release(page);
-	}
-
-	return 0;
-}
-
-/* ^^^^^^^^  above code borrowed from st driver's direct IO ^^^^^^^^^ */
-#endif
-
-
-/* Returns: -ve -> error, 0 -> done, 1 -> try indirect */
-static int
-sg_build_direct(Sg_request * srp, Sg_fd * sfp, int dxfer_len)
-{
-#ifdef SG_ALLOW_DIO_CODE
-	sg_io_hdr_t *hp = &srp->header;
-	Sg_scatter_hold *schp = &srp->data;
-	int sg_tablesize = sfp->parentdp->sg_tablesize;
-	int mx_sc_elems, res;
-	struct scsi_device *sdev = sfp->parentdp->device;
-
-	if (((unsigned long)hp->dxferp &
-			queue_dma_alignment(sdev->request_queue)) != 0)
-		return 1;
-
-	mx_sc_elems = sg_build_sgat(schp, sfp, sg_tablesize);
-        if (mx_sc_elems <= 0) {
-                return 1;
-        }
-	res = st_map_user_pages(schp->buffer, mx_sc_elems,
-				(unsigned long)hp->dxferp, dxfer_len, 
-				(SG_DXFER_TO_DEV == hp->dxfer_direction) ? 1 : 0);
-	if (res <= 0) {
-		sg_remove_scat(schp);
-		return 1;
-	}
-	schp->k_use_sg = res;
-	schp->dio_in_use = 1;
-	hp->info |= SG_INFO_DIRECT_IO;
-	return 0;
-#else
-	return 1;
-#endif
-}
-
 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;
@@ -1881,15 +1757,26 @@ 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;
+			scatter_elem_sz_prev : rem_sz;
+
+		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)) {
@@ -1897,12 +1784,12 @@ 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));
@@ -1910,223 +1797,42 @@ 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;
-}
-
-static int
-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) ||
-	    (SG_DXFER_TO_FROM_DEV == dxfer_dir)) {
-		num_xfer = (int) (new_interface ? hp->dxfer_len : hp->flags);
-		if (schp->bufflen < num_xfer)
-			num_xfer = schp->bufflen;
-	}
-	if ((num_xfer <= 0) || (schp->dio_in_use) ||
-	    (new_interface
-	     && ((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;
-}
+out:
+	for (i = 0; i < k; i++)
+		__free_pages(schp->pages[k], order);
 
-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 (--order >= 0)
+		goto retry;
 
-	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;
+	return -ENOMEM;
 }
 
 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->dio_in_use) {
-#ifdef SG_ALLOW_DIO_CODE
-			st_unmap_user_pages(sg, schp->k_use_sg, TRUE);
-#endif
-		} else {
+	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);
-	}
-	memset(schp, 0, sizeof (*schp));
-}
 
-static int
-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)
-	    || (SG_DXFER_TO_FROM_DEV == dxfer_dir)) {
-		num_xfer = hp->dxfer_len;
-		if (schp->bufflen < num_xfer)
-			num_xfer = schp->bufflen;
-	}
-	if ((num_xfer <= 0) || (schp->dio_in_use) ||
-	    (new_interface
-	     && ((SG_FLAG_NO_DXFER | SG_FLAG_MMAP_IO) & hp->flags)))
-		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;
+			kfree(schp->pages);
 		}
 	}
-
-	return 0;
+	memset(schp, 0, sizeof (*schp));
 }
 
 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",
@@ -2134,15 +1840,15 @@ 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;
+	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;
@@ -2177,24 +1883,21 @@ 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;
@@ -2208,22 +1911,13 @@ 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;
@@ -2481,53 +2175,6 @@ 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)