From: Mike Christie <[EMAIL PROTECTED]>

This patch converts sg to use the block/bio layer helpers
to map and copy data.

Signed-off-by: Mike Christie <[EMAIL PROTECTED]>
---
 drivers/scsi/sg.c | 1061 ++++++++++++++++-------------------------------------
 1 files changed, 310 insertions(+), 751 deletions(-)

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 7238b2d..8adf7ea 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -67,7 +67,6 @@ 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
 
@@ -94,9 +93,6 @@ int sg_big_buff = SG_DEF_RESERVED_SIZE;
 static int def_reserved_size = -1;     /* picks up init parameter */
 static int sg_allow_dio = SG_ALLOW_DIO_DEF;
 
-static int scatter_elem_sz = SG_SCATTER_SZ;
-static int scatter_elem_sz_prev = SG_SCATTER_SZ;
-
 #define SG_SECTOR_SZ 512
 #define SG_SECTOR_MSK (SG_SECTOR_SZ - 1)
 
@@ -114,12 +110,10 @@ static struct class_interface sg_interface = {
 
 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 */
-       char dio_in_use;        /* 0->indirect IO (or mmap), 1->dio */
        unsigned char cmd_opcode; /* first byte of command */
+       struct bio_map_data *bmd; /* reserve memory */
+       struct bio_set *bs;       /* bio pool */
 } Sg_scatter_hold;
 
 struct sg_device;              /* forward declarations */
@@ -131,6 +125,8 @@ typedef struct sg_request { /* SG_MAX_QUEUE requests 
outstanding per file */
        Sg_scatter_hold data;   /* hold buffer, perhaps scatter list */
        sg_io_hdr_t header;     /* scsi command+info, see <scsi/sg.h> */
        unsigned char sense_b[SCSI_SENSE_BUFFERSIZE];
+       struct request *request;
+       struct bio *bio;        /* ptr to bio for later unmapping */
        char res_used;          /* 1 -> using reserve buffer, 0 -> not ... */
        char orphan;            /* 1 -> drop on sight, 0 -> normal */
        char sg_io_owned;       /* 1 -> packet belongs to SG_IO */
@@ -145,7 +141,6 @@ typedef struct sg_fd {              /* holds the state of a 
file descriptor */
        int timeout;            /* defaults to SG_DEFAULT_TIMEOUT      */
        int timeout_user;       /* defaults to SG_DEFAULT_TIMEOUT_USER */
        Sg_scatter_hold reserve;        /* buffer held for this file descriptor 
*/
-       unsigned save_scat_len; /* original length of trunc. scat. element */
        Sg_request *headrp;     /* head of request slist, NULL->empty */
        struct fasync_struct *async_qp; /* used by asynchronous notification */
        Sg_request req_arr[SG_MAX_QUEUE];       /* used as singly-linked list */
@@ -173,38 +168,24 @@ 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_cmd_done(struct request *rq, int uptodate);
+static int sg_setup_req(Sg_request * srp);
 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,
-                        int tablesize);
 static ssize_t sg_new_read(Sg_fd * sfp, char __user *buf, size_t count,
                           Sg_request * srp);
 static ssize_t sg_new_write(Sg_fd * sfp, const char __user *buf, size_t count,
                            int blocking, 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 int sg_build_reserve(Sg_fd * sfp, int req_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);
 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_allow_access(unsigned char opcode, char dev_type);
-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);
@@ -301,6 +282,12 @@ sg_open(struct inode *inode, struct file *filp)
        return retval;
 }
 
+static void sg_cleanup_transfer(struct sg_request *srp)
+{
+       srp->bio = NULL;
+       srp->res_used = 0;
+}
+
 /* Following function was formerly called 'sg_close' */
 static int
 sg_release(struct inode *inode, struct file *filp)
@@ -460,7 +447,9 @@ sg_read(struct file *filp, char __user *buf, size_t count, 
loff_t * ppos)
                if (count > old_hdr->reply_len)
                        count = old_hdr->reply_len;
                if (count > SZ_SG_HEADER) {
-                       if (sg_read_oxfer(srp, buf, count - SZ_SG_HEADER)) {
+                       retval = blk_rq_complete_transfer(srp->bio, buf, count);
+                       sg_cleanup_transfer(srp);
+                       if (retval) {
                                retval = -EFAULT;
                                goto free_old_hdr;
                        }
@@ -646,18 +635,13 @@ sg_new_write(Sg_fd * sfp, const char __user *buf, size_t 
count,
                return -ENOSYS;
        }
        if (hp->flags & SG_FLAG_MMAP_IO) {
-               if (hp->dxfer_len > sfp->reserve.bufflen) {
-                       sg_remove_request(sfp, srp);
-                       return -ENOMEM; /* MMAP_IO size must fit in reserve 
buffer */
-               }
+               /*
+                * the call to mmap will have claimed the reserve buffer
+                */
                if (hp->flags & SG_FLAG_DIRECT_IO) {
                        sg_remove_request(sfp, srp);
                        return -EINVAL; /* either MMAP_IO or DIRECT_IO (not 
both) */
                }
-               if (sg_res_in_use(sfp)) {
-                       sg_remove_request(sfp, srp);
-                       return -EBUSY;  /* reserve buffer already being used */
-               }
        }
        ul_timeout = msecs_to_jiffies(srp->header.timeout);
        timeout = (ul_timeout < INT_MAX) ? ul_timeout : INT_MAX;
@@ -690,9 +674,11 @@ static int
 sg_common_write(Sg_fd * sfp, Sg_request * srp,
                unsigned char *cmnd, int timeout, int blocking)
 {
-       int k, data_dir;
+       int k;
        Sg_device *sdp = sfp->parentdp;
        sg_io_hdr_t *hp = &srp->header;
+       struct request_queue *q = sdp->device->request_queue;
+       struct request *rq;
 
        srp->data.cmd_opcode = cmnd[0]; /* hold opcode of command */
        hp->status = 0;
@@ -702,54 +688,44 @@ sg_common_write(Sg_fd * sfp, Sg_request * srp,
        hp->host_status = 0;
        hp->driver_status = 0;
        hp->resid = 0;
+
        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))) {
-               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;
+       rq = blk_get_request(q, hp->dxfer_direction == SG_DXFER_TO_DEV,
+                            GFP_NOIO);
+       if (!rq) {
+               SCSI_LOG_TIMEOUT(1, printk("sg_common_write: Could "
+                               "not allocate request\n"));
+               return -ENOMEM;
        }
+       srp->request = rq;
+
+       memset(srp->sense_b, 0, SCSI_SENSE_BUFFERSIZE);
+       rq->sense = srp->sense_b;
+       rq->sense_len = 0;
+       rq->cmd_len = hp->cmd_len;
+       memcpy(rq->cmd, cmnd, rq->cmd_len);
+       rq->timeout = timeout;
+       rq->retries = SG_DEFAULT_RETRIES;
+       rq->cmd_type = REQ_TYPE_BLOCK_PC;
+       rq->cmd_flags |= REQ_QUIET;
+       rq->end_io_data = srp;
+
        if (sdp->detached) {
                sg_finish_rem_req(srp);
                return -ENODEV;
        }
 
-       switch (hp->dxfer_direction) {
-       case SG_DXFER_TO_FROM_DEV:
-       case SG_DXFER_FROM_DEV:
-               data_dir = DMA_FROM_DEVICE;
-               break;
-       case SG_DXFER_TO_DEV:
-               data_dir = DMA_TO_DEVICE;
-               break;
-       case SG_DXFER_UNKNOWN:
-               data_dir = DMA_BIDIRECTIONAL;
-               break;
-       default:
-               data_dir = DMA_NONE;
-               break;
+       if ((k = sg_setup_req(srp))) {
+               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 */
        }
+
        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;
+       blk_execute_rq_nowait(q, NULL, rq, 1, sg_cmd_done);
+       return 0;
 }
 
 static int
@@ -838,14 +814,13 @@ sg_ioctl(struct inode *inode, struct file *filp,
                result = get_user(val, ip);
                if (result)
                        return result;
-               if (val) {
+               if (val)
+                       /*
+                        * We should always be allocated mem from the right
+                        * limit, so maybe this should always be zero?.
+                        */
                        sfp->low_dma = 1;
-                       if ((0 == sfp->low_dma) && (0 == sg_res_in_use(sfp))) {
-                               val = (int) sfp->reserve.bufflen;
-                               sg_remove_scat(&sfp->reserve);
-                               sg_build_reserve(sfp, val);
-                       }
-               } else {
+               else {
                        if (sdp->detached)
                                return -ENODEV;
                        sfp->low_dma = sdp->device->host->unchecked_isa_dma;
@@ -914,14 +889,8 @@ sg_ioctl(struct inode *inode, struct file *filp,
                 if (val < 0)
                         return -EINVAL;
                val = min_t(int, val,
-                               sdp->device->request_queue->max_sectors * 512);
-               if (val != sfp->reserve.bufflen) {
-                       if (sg_res_in_use(sfp) || sfp->mmap_called)
-                               return -EBUSY;
-                       sg_remove_scat(&sfp->reserve);
-                       sg_build_reserve(sfp, val);
-               }
-               return 0;
+                           sdp->device->request_queue->max_sectors * 512);
+               return sg_build_reserve(sfp, val);
        case SG_GET_RESERVED_SIZE:
                val = min_t(int, sfp->reserve.bufflen,
                                sdp->device->request_queue->max_sectors * 512);
@@ -1060,9 +1029,6 @@ sg_ioctl(struct inode *inode, struct file *filp,
                if (sdp->detached)
                        return -ENODEV;
                return scsi_ioctl(sdp->device, cmd_in, p);
-       case BLKSECTGET:
-               return put_user(sdp->device->request_queue->max_sectors * 512,
-                               ip);
        default:
                if (read_only)
                        return -EPERM;  /* don't know so take safe approach */
@@ -1148,72 +1114,53 @@ static struct page *
 sg_vma_nopage(struct vm_area_struct *vma, unsigned long addr, int *type)
 {
        Sg_fd *sfp;
-       struct page *page = NOPAGE_SIGBUS;
-       unsigned long offset, len, sa;
-       Sg_scatter_hold *rsv_schp;
-       struct scatterlist *sg;
-       int k;
 
        if ((NULL == vma) || (!(sfp = (Sg_fd *) vma->vm_private_data)))
-               return page;
-       rsv_schp = &sfp->reserve;
-       offset = addr - vma->vm_start;
-       if (offset >= rsv_schp->bufflen)
-               return page;
-       SCSI_LOG_TIMEOUT(3, printk("sg_vma_nopage: 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)) {
-               len = vma->vm_end - sa;
-               len = (len < sg->length) ? len : sg->length;
-               if (offset < len) {
-                       page = virt_to_page(page_address(sg->page) + offset);
-                       get_page(page); /* increment page count */
-                       break;
-               }
-               sa += len;
-               offset -= len;
-       }
+               return NOPAGE_SIGBUS;
 
-       if (type)
-               *type = VM_FAULT_MINOR;
-       return page;
+       return blk_rq_vma_nopage(sfp->reserve.bmd, vma, addr, type);
+}
+
+static void
+sg_vma_close(struct vm_area_struct *vma)
+{
+       Sg_fd *sfp = vma->vm_private_data;
+
+       if (!sfp || !sfp->reserve.bmd)
+               return;
+       blk_rq_mmap_close(sfp->reserve.bmd);
+       sfp->reserve.bmd = NULL;
 }
 
 static struct vm_operations_struct sg_mmap_vm_ops = {
        .nopage = sg_vma_nopage,
+       .close = sg_vma_close,
 };
 
 static int
 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;
 
        if ((!filp) || (!vma) || (!(sfp = (Sg_fd *) filp->private_data)))
                return -ENXIO;
-       req_sz = vma->vm_end - vma->vm_start;
-       SCSI_LOG_TIMEOUT(3, printk("sg_mmap starting, vm_start=%p, len=%d\n",
-                                  (void *) vma->vm_start, (int) req_sz));
-       if (vma->vm_pgoff)
-               return -EINVAL; /* want no offset */
-       rsv_schp = &sfp->reserve;
-       if (req_sz > rsv_schp->bufflen)
-               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)) {
-               len = vma->vm_end - sa;
-               len = (len < sg->length) ? len : sg->length;
-               sa += len;
-       }
+       if (sfp->reserve.bmd)
+               return -ENXIO;
+       if (!sfp->reserve.bs)
+               return -ENOMEM;
+
+       SCSI_LOG_TIMEOUT(3, printk("sg_mmap starting, vm_start=%p\n",
+                                  (void *) vma->vm_start));
+
+       /*
+        * This only allocates the buffer and checks we can execute the op.
+        * We do not build the request until it is sent down through the write.
+        */
+       sfp->reserve.bmd = blk_rq_mmap_open(sfp->reserve.bs,
+                                           
sfp->parentdp->device->request_queue,
+                                           vma);
+       if (!sfp->reserve.bmd)
+               return -ENOMEM;
 
        sfp->mmap_called = 1;
        vma->vm_flags |= VM_RESERVED;
@@ -1223,18 +1170,18 @@ sg_mmap(struct file *filp, struct vm_area_struct *vma)
 }
 
 /* This function is a "bottom half" handler that is called by the
- * mid level when a command is completed (or has failed). */
+ * block level when a command is completed (or has failed). */
 static void
-sg_cmd_done(void *data, char *sense, int result, int resid)
+sg_cmd_done(struct request *rq, int uptodate)
 {
-       Sg_request *srp = data;
+       Sg_request *srp = rq->end_io_data;
        Sg_device *sdp = NULL;
        Sg_fd *sfp;
        unsigned long iflags;
        unsigned int ms;
 
        if (NULL == srp) {
-               printk(KERN_ERR "sg_cmd_done: NULL request\n");
+               __blk_put_request(rq->q, rq);
                return;
        }
        sfp = srp->parentfp;
@@ -1247,29 +1194,28 @@ sg_cmd_done(void *data, char *sense, int result, int 
resid)
 
 
        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));
-       srp->header.resid = resid;
+                       sdp->disk->disk_name, srp->header.pack_id, rq->errors));
+       srp->header.resid = rq->data_len;
        ms = jiffies_to_msecs(jiffies);
        srp->header.duration = (ms > srp->header.duration) ?
                                (ms - srp->header.duration) : 0;
-       if (0 != result) {
+       if (0 != rq->errors) {
                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);
-               srp->header.host_status = host_byte(result);
-               srp->header.driver_status = driver_byte(result);
+               srp->header.status = 0xff & rq->errors;
+               srp->header.masked_status = status_byte(rq->errors);
+               srp->header.msg_status = msg_byte(rq->errors);
+               srp->header.host_status = host_byte(rq->errors);
+               srp->header.driver_status = driver_byte(rq->errors);
                if ((sdp->sgdebug > 0) &&
                    ((CHECK_CONDITION == srp->header.masked_status) ||
                     (COMMAND_TERMINATED == srp->header.masked_status)))
-                       __scsi_print_sense("sg_cmd_done", sense,
-                                          SCSI_SENSE_BUFFERSIZE);
+                       __scsi_print_sense("sg_cmd_done", rq->sense,
+                                          rq->sense_len);
 
                /* Following if statement is a patch supplied by Eric Youngdale 
*/
-               if (driver_byte(result) != 0
-                   && scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, 
&sshdr)
+               if (driver_byte(rq->errors) != 0
+                   && scsi_normalize_sense(rq->sense, rq->sense_len, &sshdr)
                    && !scsi_sense_is_deferred(&sshdr)
                    && sshdr.sense_key == UNIT_ATTENTION
                    && sdp->device->removable) {
@@ -1278,12 +1224,14 @@ sg_cmd_done(void *data, char *sense, int result, int 
resid)
                        sdp->device->changed = 1;
                }
        }
+
+       srp->request = NULL;
+       __blk_put_request(rq->q, rq);
        /* Rely on write phase to clean out srp status values, so no "else" */
 
        if (sfp->closed) {      /* whoops this fd already released, cleanup */
                SCSI_LOG_TIMEOUT(1, printk("sg_cmd_done: already closed, 
freeing ...\n"));
                sg_finish_rem_req(srp);
-               srp = NULL;
                if (NULL == sfp->headrp) {
                        SCSI_LOG_TIMEOUT(1, printk("sg_cmd_done: already 
closed, final cleanup\n"));
                        if (0 == sg_remove_sfp(sdp, sfp)) {     /* device still 
present */
@@ -1294,10 +1242,8 @@ sg_cmd_done(void *data, char *sense, int result, int 
resid)
        } else if (srp && srp->orphan) {
                if (sfp->keep_orphan)
                        srp->sg_io_owned = 0;
-               else {
+               else
                        sg_finish_rem_req(srp);
-                       srp = NULL;
-               }
        }
        if (sfp && srp) {
                /* Now wake up any sg_read() that is waiting for this packet. */
@@ -1521,7 +1467,6 @@ sg_remove(struct class_device *cl_dev, struct 
class_interface *cl_intf)
                msleep(10);     /* dirty detach so delay device destruction */
 }
 
-module_param_named(scatter_elem_sz, scatter_elem_sz, int, S_IRUGO | S_IWUSR);
 module_param_named(def_reserved_size, def_reserved_size, int,
                   S_IRUGO | S_IWUSR);
 module_param_named(allow_dio, sg_allow_dio, int, S_IRUGO | S_IWUSR);
@@ -1532,8 +1477,6 @@ MODULE_LICENSE("GPL");
 MODULE_VERSION(SG_VERSION_STR);
 MODULE_ALIAS_CHARDEV_MAJOR(SCSI_GENERIC_MAJOR);
 
-MODULE_PARM_DESC(scatter_elem_sz, "scatter gather element "
-                "size (default: max(SG_SCATTER_SZ, PAGE_SIZE))");
 MODULE_PARM_DESC(def_reserved_size, "size of buffer reserved for each fd");
 MODULE_PARM_DESC(allow_dio, "allow direct I/O (default: 0 (disallow))");
 
@@ -1542,10 +1485,6 @@ init_sg(void)
 {
        int rc;
 
-       if (scatter_elem_sz < PAGE_SIZE) {
-               scatter_elem_sz = PAGE_SIZE;
-               scatter_elem_sz_prev = scatter_elem_sz;
-       }
        if (def_reserved_size >= 0)
                sg_big_buff = def_reserved_size;
        else
@@ -1589,602 +1528,279 @@ exit_sg(void)
 }
 
 static int
-sg_start_req(Sg_request * srp)
+sg_setup_req(Sg_request * srp)
 {
-       int res;
+       struct request *rq = srp->request;
        Sg_fd *sfp = srp->parentfp;
        sg_io_hdr_t *hp = &srp->header;
+       struct sg_iovec *u_iov;
        int dxfer_len = (int) hp->dxfer_len;
        int dxfer_dir = hp->dxfer_direction;
-       Sg_scatter_hold *req_schp = &srp->data;
-       Sg_scatter_hold *rsv_schp = &sfp->reserve;
+       int new_interface = ('\0' == hp->interface_id) ? 0 : 1;
+       int res = 0, num_xfer = 0, size;
 
-       SCSI_LOG_TIMEOUT(4, printk("sg_start_req: dxfer_len=%d\n", dxfer_len));
-       if ((dxfer_len <= 0) || (dxfer_dir == SG_DXFER_NONE))
+       SCSI_LOG_TIMEOUT(4, printk("sg_setup_req: dxfer_len=%d\n", dxfer_len));
+
+       /* no transfer */
+       if ((dxfer_len <= 0) || (dxfer_dir == SG_DXFER_NONE) ||
+         (new_interface && (SG_FLAG_NO_DXFER & hp->flags)))
                return 0;
+
+       /* mmap */
+       if (new_interface && (SG_FLAG_MMAP_IO & hp->flags)) {
+               res = blk_rq_setup_mmap_buffer(rq, sfp->reserve.bmd,
+                                              dxfer_len, GFP_NOIO);
+               if (res)
+                       goto fail;
+               goto done;
+       }
+
+       /* dio */
        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;
+               res = blk_rq_setup_buffer(sfp->reserve.bs, rq, hp->dxferp,
+                                         dxfer_len, GFP_NOIO);
+               if (!res) {
+                       hp->info |= SG_INFO_DIRECT_IO;
+                       goto done;
                }
+               /* drop down to copy */
        }
-       return 0;
-}
-
-static void
-sg_finish_rem_req(Sg_request * srp)
-{
-       Sg_fd *sfp = srp->parentfp;
-       Sg_scatter_hold *req_schp = &srp->data;
-
-       SCSI_LOG_TIMEOUT(4, printk("sg_finish_rem_req: res_used=%d\n", (int) 
srp->res_used));
-       if (srp->res_used)
-               sg_unlink_reserve(sfp, srp);
-       else
-               sg_remove_scat(req_schp);
-       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);
-       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)
-               return -ENOMEM;
-       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;
+       /* copy */
+       /* old interface put SG_DXFER_TO_DEV/SG_DXFER_TO_FROM_DEV in flags */
+       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 (num_xfer > dxfer_len)
+                       num_xfer = dxfer_len;
+       }
 
-       /* Hmm? */
-       if (count == 0)
-               return 0;
+       SCSI_LOG_TIMEOUT(4, printk("sg_setup_req: Try xfer num_xfer=%d, "
+                       "iovec_count=%d\n", dxfer_len, hp->iovec_count));
 
-       if ((pages = kmalloc(max_pages * sizeof(*pages), GFP_ATOMIC)) == NULL)
-               return -ENOMEM;
+       if (!hp->iovec_count) {
+               struct sg_iovec iov;
 
-        /* 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 (TestSetPageLocked(pages[i]))
-                  goto out_unlock; */
-        }
+               iov.iov_base = hp->dxferp;
+               iov.iov_len = num_xfer;
 
-       sgl[0].page = pages[0];
-       sgl[0].offset = 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++) {
-                       sgl[i].page = pages[i]; 
-                       sgl[i].length = count < PAGE_SIZE ? count : PAGE_SIZE;
-                       count -= PAGE_SIZE;
-               }
-       }
-       else {
-               sgl[0].length = count;
+               res = blk_rq_copy_user_iov(sfp->reserve.bs, rq, &iov, 1,
+                                          dxfer_len, GFP_NOIO);
+               if (res)
+                       goto fail;
+               goto done;
        }
 
-       kfree(pages);
-       return nr_pages;
-
- out_unmap:
-       if (res > 0) {
-               for (j=0; j < res; j++)
-                       page_cache_release(pages[j]);
-               res = 0;
+       if (!access_ok(VERIFY_READ, hp->dxferp,
+                       SZ_SG_IOVEC * hp->iovec_count)) {
+               res = -EFAULT;
+               goto fail;
        }
-       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 = sgl[i].page;
 
-               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);
+       size = SZ_SG_IOVEC * hp->iovec_count;
+       u_iov = kmalloc(size, GFP_KERNEL);
+       if (!u_iov) {
+               res = -ENOMEM;
+               goto fail;
        }
 
-       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 (copy_from_user(u_iov, hp->dxferp, size)) {
+               kfree(u_iov);
+               res = -EFAULT;
+               goto fail;
+       }
 
-       if (((unsigned long)hp->dxferp &
-                       queue_dma_alignment(sdev->request_queue)) != 0)
-               return 1;
+       res = blk_rq_copy_user_iov(sfp->reserve.bs, rq, u_iov, hp->iovec_count,
+                                  dxfer_len, GFP_NOIO);
+       kfree(u_iov);
+       if (res)
+               goto fail;
 
-       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;
+done:
+       /* the blk/bio layer handles mmap cleanup */
+       if (!(new_interface && (SG_FLAG_MMAP_IO & hp->flags)))
+               /* must save for later unmapping */
+               srp->bio = rq->bio;
+       srp->res_used = 1;
        return 0;
-#else
-       return 1;
-#endif
+
+fail:
+       return res;
 }
 
-static int
-sg_build_indirect(Sg_scatter_hold * schp, Sg_fd * sfp, int buff_size)
+static void
+sg_finish_rem_req(Sg_request * srp)
 {
-       struct scatterlist *sg;
-       int ret_sz = 0, k, rem_sz, num, mx_sc_elems;
-       int sg_tablesize = sfp->parentdp->sg_tablesize;
-       int blk_size = buff_size;
-       struct page *p = NULL;
-
-       if (blk_size < 0)
-               return -EFAULT;
-       if (0 == blk_size)
-               ++blk_size;     /* don't know why */
-/* round request up to next highest SG_SECTOR_SZ byte boundary */
-       blk_size = (blk_size + SG_SECTOR_MSK) & (~SG_SECTOR_MSK);
-       SCSI_LOG_TIMEOUT(4, printk("sg_build_indirect: buff_size=%d, 
blk_size=%d\n",
-                                  buff_size, blk_size));
-
-       /* N.B. ret_sz carried into this block ... */
-       mx_sc_elems = sg_build_sgat(schp, sfp, sg_tablesize);
-       if (mx_sc_elems < 0)
-               return mx_sc_elems;     /* most likely -ENOMEM */
-
-       num = scatter_elem_sz;
-       if (unlikely(num != scatter_elem_sz_prev)) {
-               if (num < PAGE_SIZE) {
-                       scatter_elem_sz = PAGE_SIZE;
-                       scatter_elem_sz_prev = PAGE_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)) {
-               
-               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;
-
-               if (num == scatter_elem_sz_prev) {
-                       if (unlikely(ret_sz > scatter_elem_sz_prev)) {
-                               scatter_elem_sz = ret_sz;
-                               scatter_elem_sz_prev = ret_sz;
-                       }
-               }
-               sg->page = p;
-               sg->length = (ret_sz > num) ? num : ret_sz;
-
-               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->k_use_sg = k;
-       SCSI_LOG_TIMEOUT(5, printk("sg_build_indirect: k_use_sg=%d, "
-                        "rem_sz=%d\n", k, rem_sz));
+       Sg_fd *sfp = srp->parentfp;
 
-       schp->bufflen = blk_size;
-       if (rem_sz > 0) /* must have failed */
-               return -ENOMEM;
+       SCSI_LOG_TIMEOUT(4, printk("sg_finish_rem_req: res_used=%d\n", (int) 
srp->res_used));
 
-       return 0;
+       if (srp->bio)
+               /*
+                * buffer is left from something like a signal or close
+                * which was being accessed at the time. We cannot copy
+                * back to userspace so just release buffers.
+                *
+                * BUG: the old sg.c and this code, can get run from a softirq
+                * and if dio was used then we need process context.
+                * TODO: either document that you cannot use DIO and the feature
+                * which closes devices or interrupts IO while DIO is in
+                * progress. Or do something like James process context exec
+                */
+               blk_rq_destroy_buffer(srp->bio);
+       sg_cleanup_transfer(srp);
+       sg_remove_request(sfp, srp);
 }
 
 static int
-sg_write_xfer(Sg_request * srp)
+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;
+       int res = 0, num_xfer = 0;
+       int dxfer_dir = hp->dxfer_direction;
 
-       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)))
+       if (new_interface && (SG_FLAG_NO_DXFER & 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));
+       SCSI_LOG_TIMEOUT(4, printk("sg_read_xfer\n"));
+
+       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 (iovec_count) {
-               onum = iovec_count;
-               if (!access_ok(VERIFY_READ, hp->dxferp, SZ_SG_IOVEC * onum))
+               int size;
+               struct sg_iovec *u_iov;
+
+               if (!access_ok(VERIFY_READ, hp->dxferp,
+                             SZ_SG_IOVEC * iovec_count))
                        return -EFAULT;
-       } else
-               onum = 1;
 
-       ksglen = sg->length;
-       p = page_address(sg->page);
-       for (j = 0, k = 0; j < onum; ++j) {
-               res = sg_u_iovec(hp, iovec_count, j, 1, &usglen, &up);
-               if (res)
-                       return res;
+               size = SZ_SG_IOVEC * iovec_count;
+               u_iov = kmalloc(size, GFP_KERNEL);
+               if (!u_iov)
+                       return -ENOMEM;
 
-               for (; p; sg = sg_next(sg), ksglen = sg->length,
-                    p = page_address(sg->page)) {
-                       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;
+               if (copy_from_user(u_iov, hp->dxferp, size)) {
+                       kfree(u_iov);
+                       return -EFAULT;
                }
-       }
 
-       return 0;
+               res = blk_rq_uncopy_user_iov(srp->bio, u_iov, iovec_count);
+               kfree(u_iov);
+       } else if (!(new_interface && (SG_FLAG_MMAP_IO & hp->flags)))
+               /*
+                * dio or non iovec copy user. For mmap blk/bio layer
+                * handles the cleanup.
+                */
+               res = blk_rq_complete_transfer(srp->bio, hp->dxferp, num_xfer);
+       sg_cleanup_transfer(srp);
+       return res;
 }
 
 static int
-sg_u_iovec(sg_io_hdr_t * hp, int sg_num, int ind,
-          int wr_xf, int *countp, unsigned char __user **up)
+sg_res_in_use(Sg_fd * sfp)
 {
-       int num_xfer = (int) hp->dxfer_len;
-       unsigned char __user *p = hp->dxferp;
-       int count;
+       const Sg_request *srp;
+       unsigned long iflags;
 
-       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;
+       read_lock_irqsave(&sfp->rq_list_lock, iflags);
+       for (srp = sfp->headrp; srp; srp = srp->nextrp)
+               if (srp->res_used)
+                       break;
+       read_unlock_irqrestore(&sfp->rq_list_lock, iflags);
+       return srp ? 1 : 0;
 }
 
 static void
-sg_remove_scat(Sg_scatter_hold * schp)
+sg_calc_reserve_settings(struct request_queue *q, int req_size, int *order,
+                        int *nr_segs)
 {
-       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;
+       unsigned int bytes;
 
-               if (schp->dio_in_use) {
-#ifdef SG_ALLOW_DIO_CODE
-                       st_unmap_user_pages(sg, schp->k_use_sg, TRUE);
-#endif
-               } else {
-                       int k;
-
-                       for (k = 0; (k < schp->k_use_sg) && sg->page;
-                            ++k, sg = sg_next(sg)) {
-                               SCSI_LOG_TIMEOUT(5, printk(
-                                   "sg_remove_scat: k=%d, pg=0x%p, len=%d\n",
-                                   k, sg->page, sg->length));
-                               sg_page_free(sg->page, sg->length);
-                       }
-               }
-               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;
+       *order = 0;
+       *nr_segs = 0;
 
-       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 (req_size <= PAGE_SIZE) {
+               bytes = PAGE_SIZE;
+               *order = 0;
+               goto calc_segs;
        }
-       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);
-       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)) {
-                       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;
-               }
+       if (!(q->queue_flags & (1 << QUEUE_FLAG_CLUSTER))) {
+               *order = 0;
+               bytes = PAGE_SIZE;
+               goto calc_segs;
        }
 
-       return 0;
-}
-
-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",
-                                  num_read_xfer));
-       if ((!outp) || (num_read_xfer <= 0))
-               return 0;
+       bytes = min(q->max_segment_size, q->max_hw_sectors << 9);
+       if (bytes > BIO_MAX_SIZE)
+               bytes = BIO_MAX_SIZE;
+       else if (bytes > req_size)
+               bytes = req_size;
+       *order = get_order(bytes);
 
-       for (k = 0; (k < schp->k_use_sg) && sg->page; ++k, sg = sg_next(sg)) {
-               num = sg->length;
-               if (num > num_read_xfer) {
-                       if (__copy_to_user(outp, page_address(sg->page),
-                                          num_read_xfer))
-                               return -EFAULT;
-                       break;
-               } else {
-                       if (__copy_to_user(outp, page_address(sg->page),
-                                          num))
-                               return -EFAULT;
-                       num_read_xfer -= num;
-                       if (num_read_xfer <= 0)
-                               break;
-                       outp += num;
-               }
-       }
-
-       return 0;
+calc_segs:
+       *nr_segs = req_size / bytes;
+       if ((bytes * (*nr_segs)) < req_size)
+               *nr_segs = *nr_segs + 1;
 }
 
-static void
+static int
 sg_build_reserve(Sg_fd * sfp, int req_size)
 {
-       Sg_scatter_hold *schp = &sfp->reserve;
+       struct request_queue *q = sfp->parentdp->device->request_queue;
+       int order = 0, nr_segs = 0, old_nr_segs;
+       struct bio_set *old_bs = NULL;
+       unsigned old_bufflen;
 
        SCSI_LOG_TIMEOUT(4, printk("sg_build_reserve: req_size=%d\n", 
req_size));
-       do {
-               if (req_size < PAGE_SIZE)
-                       req_size = PAGE_SIZE;
-               if (0 == sg_build_indirect(schp, sfp, req_size))
-                       return;
-               else
-                       sg_remove_scat(schp);
-               req_size >>= 1; /* divide by 2 */
-       } while (req_size > (PAGE_SIZE / 2));
-}
+       if (req_size < 0)
+               return -EINVAL;
 
-static void
-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;
+       if (req_size == 0)
+               return 0;
 
-       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;
-               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->bufflen = size;
-                       req_schp->b_malloc_len = rsv_schp->b_malloc_len;
-                       break;
-               } else
-                       rem -= num;
+       if (sfp->reserve.bs &&
+           (bioset_pagepool_get_size(sfp->reserve.bs) == req_size))
+               return 0;
+
+       if (sfp->mmap_called || sg_res_in_use(sfp))
+               return -EBUSY;
+
+       if (sfp->reserve.bs) {
+               old_bs = sfp->reserve.bs;
+               sfp->reserve.bs = NULL;
        }
 
-       if (k >= rsv_schp->k_use_sg)
-               SCSI_LOG_TIMEOUT(1, printk("sg_link_reserve: BAD size\n"));
-}
+       old_bufflen = sfp->reserve.bufflen = 0;
+       old_nr_segs = sfp->reserve.k_use_sg = 0;
 
-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;
+       sg_calc_reserve_settings(q, req_size, &order, &nr_segs);
+       /*
+        * the max reserve size was limited to the q->max_sectors,
+        * which fits in one bio.
+        */
+       sfp->reserve.bs = bioset_pagepool_create(1, 1, nr_segs, order);
+       if (!sfp->reserve.bs) {
+               if (old_bs) {
+                       sfp->reserve.bs = old_bs;
+                       sfp->reserve.bufflen = old_bufflen;
+                       sfp->reserve.k_use_sg = old_nr_segs;
+               }
+               return -ENOMEM;
+        }
 
-       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 (old_bs)
+               bioset_pagepool_free(old_bs);
 
-               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->sglist_len = 0;
-       sfp->save_scat_len = 0;
-       srp->res_used = 0;
+       sfp->reserve.bufflen = bioset_pagepool_get_size(sfp->reserve.bs);
+       sfp->reserve.k_use_sg = nr_segs;
+       return 0;
 }
 
 static Sg_request *
@@ -2375,12 +1991,16 @@ __sg_remove_sfp(Sg_device * sdp, Sg_fd * sfp)
                        prev_fp = fp;
                }
        }
+
        if (sfp->reserve.bufflen > 0) {
                SCSI_LOG_TIMEOUT(6, 
                        printk("__sg_remove_sfp:    bufflen=%d, k_use_sg=%d\n",
                        (int) sfp->reserve.bufflen, (int) 
sfp->reserve.k_use_sg));
-               sg_remove_scat(&sfp->reserve);
+               bioset_pagepool_free(sfp->reserve.bs);
+               sfp->reserve.bs = NULL;
+               sfp->reserve.bufflen  = 0;
        }
+
        sfp->parentdp = NULL;
        SCSI_LOG_TIMEOUT(6, printk("__sg_remove_sfp:    sfp=0x%p\n", sfp));
        kfree(sfp);
@@ -2425,67 +2045,6 @@ sg_remove_sfp(Sg_device * sdp, Sg_fd * sfp)
        return res;
 }
 
-static int
-sg_res_in_use(Sg_fd * sfp)
-{
-       const Sg_request *srp;
-       unsigned long iflags;
-
-       read_lock_irqsave(&sfp->rq_list_lock, iflags);
-       for (srp = sfp->headrp; srp; srp = srp->nextrp)
-               if (srp->res_used)
-                       break;
-       read_unlock_irqrestore(&sfp->rq_list_lock, iflags);
-       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);
-}
-
 #ifndef MAINTENANCE_IN_CMD
 #define MAINTENANCE_IN_CMD 0xa3
 #endif
-- 
1.5.1.2

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