[SCSI] block: make blk_rq_map_user take a NULL user-space buffer for WRITE
[safe/jmp/linux-2.6] / drivers / scsi / sg.c
index ea0edd1..8f0bd3f 100644 (file)
@@ -47,8 +47,8 @@ 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>
 
 #include "scsi.h"
 #include <scsi/scsi_dbg.h>
@@ -68,7 +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
 
@@ -117,8 +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;
@@ -136,6 +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 */
@@ -174,29 +175,24 @@ 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_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,
                         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 ssize_t sg_new_write(Sg_fd *sfp, struct file *file,
+                       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 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);
@@ -204,8 +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_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);
@@ -216,6 +210,18 @@ static int sg_last_dev(void);
 #define SZ_SG_IOVEC sizeof(sg_iovec_t)
 #define SZ_SG_REQ_INFO sizeof(sg_req_info_t)
 
+static int sg_allow_access(struct file *filp, unsigned char *cmd)
+{
+       struct sg_fd *sfp = (struct sg_fd *)filp->private_data;
+       struct request_queue *q = sfp->parentdp->device->request_queue;
+
+       if (sfp->parentdp->device->type == TYPE_SCANNER)
+               return 0;
+
+       return blk_verify_command(&q->cmd_filter,
+                                 cmd, filp->f_mode & FMODE_WRITE);
+}
+
 static int
 sg_open(struct inode *inode, struct file *filp)
 {
@@ -227,19 +233,26 @@ sg_open(struct inode *inode, struct file *filp)
        int res;
        int retval;
 
+       lock_kernel();
        nonseekable_open(inode, filp);
        SCSI_LOG_TIMEOUT(3, printk("sg_open: dev=%d, flags=0x%x\n", dev, flags));
        sdp = sg_get_dev(dev);
-       if ((!sdp) || (!sdp->device))
+       if ((!sdp) || (!sdp->device)) {
+               unlock_kernel();
                return -ENXIO;
-       if (sdp->detached)
+       }
+       if (sdp->detached) {
+               unlock_kernel();
                return -ENODEV;
+       }
 
        /* This driver's module count bumped by fops_get in <linux/fs.h> */
        /* Prevent the device driver from vanishing while we sleep */
        retval = scsi_device_get(sdp->device);
-       if (retval)
+       if (retval) {
+               unlock_kernel();
                return retval;
+       }
 
        if (!((flags & O_NONBLOCK) ||
              scsi_block_when_processing_errors(sdp->device))) {
@@ -295,10 +308,12 @@ sg_open(struct inode *inode, struct file *filp)
                retval = -ENOMEM;
                goto error_out;
        }
+       unlock_kernel();
        return 0;
 
       error_out:
        scsi_device_put(sdp->device);
+       unlock_kernel();
        return retval;
 }
 
@@ -312,7 +327,6 @@ sg_release(struct inode *inode, struct file *filp)
        if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
                return -ENXIO;
        SCSI_LOG_TIMEOUT(3, printk("sg_release: %s\n", sdp->disk->disk_name));
-       sg_fasync(-1, filp, 0); /* remove filp from async notification list */
        if (0 == sg_remove_sfp(sdp, sfp)) {     /* Returns 1 when sdp gone */
                if (!sdp->detached) {
                        scsi_device_put(sdp->device);
@@ -507,8 +521,7 @@ 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;
 }
@@ -544,7 +557,7 @@ sg_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
                return -EFAULT;
        blocking = !(filp->f_flags & O_NONBLOCK);
        if (old_hdr.reply_len < 0)
-               return sg_new_write(sfp, buf, count, blocking, 0, NULL);
+               return sg_new_write(sfp, filp, buf, count, blocking, 0, NULL);
        if (count < (SZ_SG_HEADER + 6))
                return -EIO;    /* The minimum scsi command length is 6 bytes. */
 
@@ -590,7 +603,10 @@ 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 ... */
@@ -621,8 +637,9 @@ sg_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
 }
 
 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)
+sg_new_write(Sg_fd *sfp, struct file *file, const char __user *buf,
+                size_t count, int blocking, int read_only,
+                Sg_request **o_srp)
 {
        int k;
        Sg_request *srp;
@@ -678,8 +695,7 @@ sg_new_write(Sg_fd * sfp, const char __user *buf, size_t count,
                sg_remove_request(sfp, srp);
                return -EFAULT;
        }
-       if (read_only &&
-           (!sg_allow_access(cmnd[0], sfp->parentdp->device->type))) {
+       if (read_only && sg_allow_access(file, cmnd)) {
                sg_remove_request(sfp, srp);
                return -EPERM;
        }
@@ -710,16 +726,12 @@ 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;
@@ -741,20 +753,11 @@ 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
@@ -783,6 +786,7 @@ sg_ioctl(struct inode *inode, struct file *filp,
 
        if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
                return -ENXIO;
+
        SCSI_LOG_TIMEOUT(3, printk("sg_ioctl: %s, cmd=0x%x\n",
                                   sdp->disk->disk_name, (int) cmd_in));
        read_only = (O_RDWR != (filp->f_flags & O_ACCMODE));
@@ -799,7 +803,7 @@ sg_ioctl(struct inode *inode, struct file *filp,
                        if (!access_ok(VERIFY_WRITE, p, SZ_SG_IO_HDR))
                                return -EFAULT;
                        result =
-                           sg_new_write(sfp, p, SZ_SG_IO_HDR,
+                           sg_new_write(sfp, filp, p, SZ_SG_IO_HDR,
                                         blocking, read_only, &srp);
                        if (result < 0)
                                return result;
@@ -1026,6 +1030,9 @@ sg_ioctl(struct inode *inode, struct file *filp,
                case SG_SCSI_RESET_DEVICE:
                        val = SCSI_TRY_RESET_DEVICE;
                        break;
+               case SG_SCSI_RESET_TARGET:
+                       val = SCSI_TRY_RESET_TARGET;
+                       break;
                case SG_SCSI_RESET_BUS:
                        val = SCSI_TRY_RESET_BUS;
                        break;
@@ -1048,10 +1055,10 @@ sg_ioctl(struct inode *inode, struct file *filp,
 
                        if (copy_from_user(&opcode, siocp->data, 1))
                                return -EFAULT;
-                       if (!sg_allow_access(opcode, sdp->device->type))
+                       if (sg_allow_access(filp, &opcode))
                                return -EPERM;
                }
-               return sg_scsi_ioctl(filp, sdp->device->request_queue, NULL, p);
+               return sg_scsi_ioctl(sdp->device->request_queue, NULL, filp->f_mode, p);
        case SG_SET_DEBUG:
                result = get_user(val, ip);
                if (result)
@@ -1166,8 +1173,7 @@ 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;
@@ -1177,15 +1183,14 @@ 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 */
@@ -1207,8 +1212,7 @@ 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;
@@ -1222,11 +1226,10 @@ 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;
        }
 
@@ -1237,16 +1240,19 @@ 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");
@@ -1260,6 +1266,9 @@ 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));
@@ -1270,7 +1279,6 @@ 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);
@@ -1441,12 +1449,10 @@ sg_add(struct device *cl_dev, struct class_interface *cl_intf)
        if (sg_sysfs_valid) {
                struct device *sg_class_member;
 
-               sg_class_member = device_create_drvdata(sg_sysfs_class,
-                                                       cl_dev->parent,
-                                                       MKDEV(SCSI_GENERIC_MAJOR,
-                                                             sdp->index),
-                                                       sdp,
-                                                       "%s", disk->disk_name);
+               sg_class_member = device_create(sg_sysfs_class, cl_dev->parent,
+                                               MKDEV(SCSI_GENERIC_MAJOR,
+                                                     sdp->index),
+                                               sdp, "%s", disk->disk_name);
                if (IS_ERR(sg_class_member)) {
                        printk(KERN_ERR "sg_add: "
                               "device_create failed\n");
@@ -1608,37 +1614,81 @@ 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;
+               md->offset = 0;
+               md->null_mapped = hp->dxferp ? 0 : 1;
        }
-       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
@@ -1652,186 +1702,37 @@ 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 (TestSetPageLocked(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;
@@ -1855,15 +1756,26 @@ 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)) {
@@ -1871,12 +1783,12 @@ 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));
@@ -1884,223 +1796,42 @@ 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",
@@ -2108,15 +1839,15 @@ 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;
@@ -2151,24 +1882,21 @@ 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;
@@ -2182,22 +1910,13 @@ 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;
@@ -2455,77 +2174,6 @@ 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);
-}
-
-#ifndef MAINTENANCE_IN_CMD
-#define MAINTENANCE_IN_CMD 0xa3
-#endif
-
-static unsigned char allow_ops[] = { TEST_UNIT_READY, REQUEST_SENSE,
-       INQUIRY, READ_CAPACITY, READ_BUFFER, READ_6, READ_10, READ_12,
-       READ_16, MODE_SENSE, MODE_SENSE_10, LOG_SENSE, REPORT_LUNS,
-       SERVICE_ACTION_IN, RECEIVE_DIAGNOSTIC, READ_LONG, MAINTENANCE_IN_CMD
-};
-
-static int
-sg_allow_access(unsigned char opcode, char dev_type)
-{
-       int k;
-
-       if (TYPE_SCANNER == dev_type)   /* TYPE_ROM maybe burner */
-               return 1;
-       for (k = 0; k < sizeof (allow_ops); ++k) {
-               if (opcode == allow_ops[k])
-                       return 1;
-       }
-       return 0;
-}
-
 #ifdef CONFIG_SCSI_PROC_FS
 static int
 sg_idr_max_id(int id, void *p, void *data)