1 files changed, 165 insertions, 577 deletions

diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index cb942a9b580f..d9764f0bc82f 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -131,13 +131,6 @@ enum {
         IDETAPE_DIR_WRITE = (1 << 2),
 };
 
-struct idetape_bh {
-        u32 b_size;
-        atomic_t b_count;
-        struct idetape_bh *b_reqnext;
-        char *b_data;
-};
-
 /* Tape door status */
 #define DOOR_UNLOCKED                   0
 #define DOOR_LOCKED                     1
@@ -219,18 +212,12 @@ typedef struct ide_tape_obj {
 
         /* Data buffer size chosen based on the tape's recommendation */
         int buffer_size;
-        /* merge buffer */
-        struct idetape_bh *merge_bh;
-        /* size of the merge buffer */
-        int merge_bh_size;
-        /* pointer to current buffer head within the merge buffer */
-        struct idetape_bh *bh;
-        char *b_data;
-        int b_count;
-
-        int pages_per_buffer;
-        /* Wasted space in each stage */
-        int excess_bh_size;
+        /* Staging buffer of buffer_size bytes */
+        void *buf;
+        /* The read/write cursor */
+        void *cur;
+        /* The number of valid bytes in buf */
+        size_t valid;
 
         /* Measures average tape speed */
         unsigned long avg_time;
@@ -297,84 +284,6 @@ static struct ide_tape_obj *ide_tape_chrdev_get(unsigned int i)
         return tape;
 }
 
-static int idetape_input_buffers(ide_drive_t *drive, struct ide_atapi_pc *pc,
-                                  unsigned int bcount)
-{
-        struct idetape_bh *bh = pc->bh;
-        int count;
-
-        while (bcount) {
-                if (bh == NULL)
-                        break;
-                count = min(
-                        (unsigned int)(bh->b_size - atomic_read(&bh->b_count)),
-                        bcount);
-                drive->hwif->tp_ops->input_data(drive, NULL, bh->b_data +
-                                        atomic_read(&bh->b_count), count);
-                bcount -= count;
-                atomic_add(count, &bh->b_count);
-                if (atomic_read(&bh->b_count) == bh->b_size) {
-                        bh = bh->b_reqnext;
-                        if (bh)
-                                atomic_set(&bh->b_count, 0);
-                }
-        }
-
-        pc->bh = bh;
-
-        return bcount;
-}
-
-static int idetape_output_buffers(ide_drive_t *drive, struct ide_atapi_pc *pc,
-                                   unsigned int bcount)
-{
-        struct idetape_bh *bh = pc->bh;
-        int count;
-
-        while (bcount) {
-                if (bh == NULL)
-                        break;
-                count = min((unsigned int)pc->b_count, (unsigned int)bcount);
-                drive->hwif->tp_ops->output_data(drive, NULL, pc->b_data, count);
-                bcount -= count;
-                pc->b_data += count;
-                pc->b_count -= count;
-                if (!pc->b_count) {
-                        bh = bh->b_reqnext;
-                        pc->bh = bh;
-                        if (bh) {
-                                pc->b_data = bh->b_data;
-                                pc->b_count = atomic_read(&bh->b_count);
-                        }
-                }
-        }
-
-        return bcount;
-}
-
-static void idetape_update_buffers(ide_drive_t *drive, struct ide_atapi_pc *pc)
-{
-        struct idetape_bh *bh = pc->bh;
-        int count;
-        unsigned int bcount = pc->xferred;
-
-        if (pc->flags & PC_FLAG_WRITING)
-                return;
-        while (bcount) {
-                if (bh == NULL) {
-                        printk(KERN_ERR "ide-tape: bh == NULL in %s\n",
-                                        __func__);
-                        return;
-                }
-                count = min((unsigned int)bh->b_size, (unsigned int)bcount);
-                atomic_set(&bh->b_count, count);
-                if (atomic_read(&bh->b_count) == bh->b_size)
-                        bh = bh->b_reqnext;
-                bcount -= count;
-        }
-        pc->bh = bh;
-}
-
 /*
  * called on each failed packet command retry to analyze the request sense. We
  * currently do not utilize this information.
@@ -392,12 +301,10 @@ static void idetape_analyze_error(ide_drive_t *drive, u8 *sense)
                  pc->c[0], tape->sense_key, tape->asc, tape->ascq);
 
         /* Correct pc->xferred by asking the tape.       */
-        if (pc->flags & PC_FLAG_DMA_ERROR) {
+        if (pc->flags & PC_FLAG_DMA_ERROR)
                 pc->xferred = pc->req_xfer -
                         tape->blk_size *
                         get_unaligned_be32(&sense[3]);
-                idetape_update_buffers(drive, pc);
-        }
 
         /*
          * If error was the result of a zero-length read or write command,
@@ -436,29 +343,6 @@ static void idetape_analyze_error(ide_drive_t *drive, u8 *sense)
         }
 }
 
-/* Free data buffers completely. */
-static void ide_tape_kfree_buffer(idetape_tape_t *tape)
-{
-        struct idetape_bh *prev_bh, *bh = tape->merge_bh;
-
-        while (bh) {
-                u32 size = bh->b_size;
-
-                while (size) {
-                        unsigned int order = fls(size >> PAGE_SHIFT)-1;
-
-                        if (bh->b_data)
-                                free_pages((unsigned long)bh->b_data, order);
-
-                        size &= (order-1);
-                        bh->b_data += (1 << order) * PAGE_SIZE;
-                }
-                prev_bh = bh;
-                bh = bh->b_reqnext;
-                kfree(prev_bh);
-        }
-}
-
 static void ide_tape_handle_dsc(ide_drive_t *);
 
 static int ide_tape_callback(ide_drive_t *drive, int dsc)
@@ -496,7 +380,7 @@ static int ide_tape_callback(ide_drive_t *drive, int dsc)
                 }
 
                 tape->first_frame += blocks;
-                rq->current_nr_sectors -= blocks;
+                rq->resid_len -= blocks * tape->blk_size;
 
                 if (pc->error) {
                         uptodate = 0;
@@ -558,19 +442,6 @@ static void ide_tape_handle_dsc(ide_drive_t *drive)
         idetape_postpone_request(drive);
 }
 
-static int ide_tape_io_buffers(ide_drive_t *drive, struct ide_atapi_pc *pc,
-                                unsigned int bcount, int write)
-{
-        unsigned int bleft;
-
-        if (write)
-                bleft = idetape_output_buffers(drive, pc, bcount);
-        else
-                bleft = idetape_input_buffers(drive, pc, bcount);
-
-        return bcount - bleft;
-}
-
 /*
  * Packet Command Interface
  *
@@ -614,12 +485,6 @@ static ide_startstop_t ide_tape_issue_pc(ide_drive_t *drive,
 {
         idetape_tape_t *tape = drive->driver_data;
 
-        if (drive->pc->c[0] == REQUEST_SENSE &&
-            pc->c[0] == REQUEST_SENSE) {
-                printk(KERN_ERR "ide-tape: possible ide-tape.c bug - "
-                        "Two request sense in serial were issued\n");
-        }
-
         if (drive->failed_pc == NULL && pc->c[0] != REQUEST_SENSE)
                 drive->failed_pc = pc;
 
@@ -628,6 +493,8 @@ static ide_startstop_t ide_tape_issue_pc(ide_drive_t *drive,
 
         if (pc->retries > IDETAPE_MAX_PC_RETRIES ||
                 (pc->flags & PC_FLAG_ABORT)) {
+                unsigned int done = blk_rq_bytes(drive->hwif->rq);
+
                 /*
                  * We will "abort" retrying a packet command in case legitimate
                  * error code was received (crossing a filemark, or end of the
@@ -647,8 +514,10 @@ static ide_startstop_t ide_tape_issue_pc(ide_drive_t *drive,
                         /* Giving up */
                         pc->error = IDE_DRV_ERROR_GENERAL;
                 }
+
                 drive->failed_pc = NULL;
                 drive->pc_callback(drive, 0);
+                ide_complete_rq(drive, -EIO, done);
                 return ide_stopped;
         }
         debug_log(DBG_SENSE, "Retry #%d, cmd = %02X\n", pc->retries, pc->c[0]);
@@ -701,7 +570,7 @@ static ide_startstop_t idetape_media_access_finished(ide_drive_t *drive)
                                 printk(KERN_ERR "ide-tape: %s: I/O error, ",
                                                 tape->name);
                         /* Retry operation */
-                        ide_retry_pc(drive, tape->disk);
+                        ide_retry_pc(drive);
                         return ide_stopped;
                 }
                 pc->error = 0;
@@ -717,27 +586,22 @@ static void ide_tape_create_rw_cmd(idetape_tape_t *tape,
                                    struct ide_atapi_pc *pc, struct request *rq,
                                    u8 opcode)
 {
-        struct idetape_bh *bh = (struct idetape_bh *)rq->special;
-        unsigned int length = rq->current_nr_sectors;
+        unsigned int length = blk_rq_sectors(rq);
 
         ide_init_pc(pc);
         put_unaligned(cpu_to_be32(length), (unsigned int *) &pc->c[1]);
         pc->c[1] = 1;
-        pc->bh = bh;
         pc->buf = NULL;
         pc->buf_size = length * tape->blk_size;
         pc->req_xfer = pc->buf_size;
         if (pc->req_xfer == tape->buffer_size)
                 pc->flags |= PC_FLAG_DMA_OK;
 
-        if (opcode == READ_6) {
+        if (opcode == READ_6)
                 pc->c[0] = READ_6;
-                atomic_set(&bh->b_count, 0);
-        } else if (opcode == WRITE_6) {
+        else if (opcode == WRITE_6) {
                 pc->c[0] = WRITE_6;
                 pc->flags |= PC_FLAG_WRITING;
-                pc->b_data = bh->b_data;
-                pc->b_count = atomic_read(&bh->b_count);
         }
 
         memcpy(rq->cmd, pc->c, 12);
@@ -753,12 +617,10 @@ static ide_startstop_t idetape_do_request(ide_drive_t *drive,
         struct ide_cmd cmd;
         u8 stat;
 
-        debug_log(DBG_SENSE, "sector: %llu, nr_sectors: %lu,"
-                        " current_nr_sectors: %u\n",
-                        (unsigned long long)rq->sector, rq->nr_sectors,
-                        rq->current_nr_sectors);
+        debug_log(DBG_SENSE, "sector: %llu, nr_sectors: %u\n"
+                  (unsigned long long)blk_rq_pos(rq), blk_rq_sectors(rq));
 
-        if (!blk_special_request(rq)) {
+        if (!(blk_special_request(rq) || blk_sense_request(rq))) {
                 /* We do not support buffer cache originated requests. */
                 printk(KERN_NOTICE "ide-tape: %s: Unsupported request in "
                         "request queue (%d)\n", drive->name, rq->cmd_type);
@@ -834,7 +696,7 @@ static ide_startstop_t idetape_do_request(ide_drive_t *drive,
                 goto out;
         }
         if (rq->cmd[13] & REQ_IDETAPE_PC1) {
-                pc = (struct ide_atapi_pc *) rq->buffer;
+                pc = (struct ide_atapi_pc *)rq->special;
                 rq->cmd[13] &= ~(REQ_IDETAPE_PC1);
                 rq->cmd[13] |= REQ_IDETAPE_PC2;
                 goto out;
@@ -846,6 +708,9 @@ static ide_startstop_t idetape_do_request(ide_drive_t *drive,
         BUG();
 
 out:
+        /* prepare sense request for this command */
+        ide_prep_sense(drive, rq);
+
         memset(&cmd, 0, sizeof(cmd));
 
         if (rq_data_dir(rq))
@@ -853,167 +718,10 @@ out:
 
         cmd.rq = rq;
 
-        return ide_tape_issue_pc(drive, &cmd, pc);
-}
-
-/*
- * The function below uses __get_free_pages to allocate a data buffer of size
- * tape->buffer_size (or a bit more). We attempt to combine sequential pages as
- * much as possible.
- *
- * It returns a pointer to the newly allocated buffer, or NULL in case of
- * failure.
- */
-static struct idetape_bh *ide_tape_kmalloc_buffer(idetape_tape_t *tape,
-                                                  int full, int clear)
-{
-        struct idetape_bh *prev_bh, *bh, *merge_bh;
-        int pages = tape->pages_per_buffer;
-        unsigned int order, b_allocd;
-        char *b_data = NULL;
-
-        merge_bh = kmalloc(sizeof(struct idetape_bh), GFP_KERNEL);
-        bh = merge_bh;
-        if (bh == NULL)
-                goto abort;
-
-        order = fls(pages) - 1;
-        bh->b_data = (char *) __get_free_pages(GFP_KERNEL, order);
-        if (!bh->b_data)
-                goto abort;
-        b_allocd = (1 << order) * PAGE_SIZE;
-        pages &= (order-1);
-
-        if (clear)
-                memset(bh->b_data, 0, b_allocd);
-        bh->b_reqnext = NULL;
-        bh->b_size = b_allocd;
-        atomic_set(&bh->b_count, full ? bh->b_size : 0);
-
-        while (pages) {
-                order = fls(pages) - 1;
-                b_data = (char *) __get_free_pages(GFP_KERNEL, order);
-                if (!b_data)
-                        goto abort;
-                b_allocd = (1 << order) * PAGE_SIZE;
-
-                if (clear)
-                        memset(b_data, 0, b_allocd);
-
-                /* newly allocated page frames below buffer header or ...*/
-                if (bh->b_data == b_data + b_allocd) {
-                        bh->b_size += b_allocd;
-                        bh->b_data -= b_allocd;
-                        if (full)
-                                atomic_add(b_allocd, &bh->b_count);
-                        continue;
-                }
-                /* they are above the header */
-                if (b_data == bh->b_data + bh->b_size) {
-                        bh->b_size += b_allocd;
-                        if (full)
-                                atomic_add(b_allocd, &bh->b_count);
-                        continue;
-                }
-                prev_bh = bh;
-                bh = kmalloc(sizeof(struct idetape_bh), GFP_KERNEL);
-                if (!bh) {
-                        free_pages((unsigned long) b_data, order);
-                        goto abort;
-                }
-                bh->b_reqnext = NULL;
-                bh->b_data = b_data;
-                bh->b_size = b_allocd;
-                atomic_set(&bh->b_count, full ? bh->b_size : 0);
-                prev_bh->b_reqnext = bh;
-
-                pages &= (order-1);
-        }
+        ide_init_sg_cmd(&cmd, pc->req_xfer);
+        ide_map_sg(drive, &cmd);
 
-        bh->b_size -= tape->excess_bh_size;
-        if (full)
-                atomic_sub(tape->excess_bh_size, &bh->b_count);
-        return merge_bh;
-abort:
-        ide_tape_kfree_buffer(tape);
-        return NULL;
-}
-
-static int idetape_copy_stage_from_user(idetape_tape_t *tape,
-                                        const char __user *buf, int n)
-{
-        struct idetape_bh *bh = tape->bh;
-        int count;
-        int ret = 0;
-
-        while (n) {
-                if (bh == NULL) {
-                        printk(KERN_ERR "ide-tape: bh == NULL in %s\n",
-                                        __func__);
-                        return 1;
-                }
-                count = min((unsigned int)
-                                (bh->b_size - atomic_read(&bh->b_count)),
-                                (unsigned int)n);
-                if (copy_from_user(bh->b_data + atomic_read(&bh->b_count), buf,
-                                count))
-                        ret = 1;
-                n -= count;
-                atomic_add(count, &bh->b_count);
-                buf += count;
-                if (atomic_read(&bh->b_count) == bh->b_size) {
-                        bh = bh->b_reqnext;
-                        if (bh)
-                                atomic_set(&bh->b_count, 0);
-                }
-        }
-        tape->bh = bh;
-        return ret;
-}
-
-static int idetape_copy_stage_to_user(idetape_tape_t *tape, char __user *buf,
-                                      int n)
-{
-        struct idetape_bh *bh = tape->bh;
-        int count;
-        int ret = 0;
-
-        while (n) {
-                if (bh == NULL) {
-                        printk(KERN_ERR "ide-tape: bh == NULL in %s\n",
-                                        __func__);
-                        return 1;
-                }
-                count = min(tape->b_count, n);
-                if  (copy_to_user(buf, tape->b_data, count))
-                        ret = 1;
-                n -= count;
-                tape->b_data += count;
-                tape->b_count -= count;
-                buf += count;
-                if (!tape->b_count) {
-                        bh = bh->b_reqnext;
-                        tape->bh = bh;
-                        if (bh) {
-                                tape->b_data = bh->b_data;
-                                tape->b_count = atomic_read(&bh->b_count);
-                        }
-                }
-        }
-        return ret;
-}
-
-static void idetape_init_merge_buffer(idetape_tape_t *tape)
-{
-        struct idetape_bh *bh = tape->merge_bh;
-        tape->bh = tape->merge_bh;
-
-        if (tape->chrdev_dir == IDETAPE_DIR_WRITE)
-                atomic_set(&bh->b_count, 0);
-        else {
-                tape->b_data = bh->b_data;
-                tape->b_count = atomic_read(&bh->b_count);
-        }
+        return ide_tape_issue_pc(drive, &cmd, pc);
 }
 
 /*
@@ -1113,10 +821,10 @@ static void __ide_tape_discard_merge_buffer(ide_drive_t *drive)
                 return;
 
         clear_bit(IDE_AFLAG_FILEMARK, &drive->atapi_flags);
-        tape->merge_bh_size = 0;
-        if (tape->merge_bh != NULL) {
-                ide_tape_kfree_buffer(tape);
-                tape->merge_bh = NULL;
+        tape->valid = 0;
+        if (tape->buf != NULL) {
+                kfree(tape->buf);
+                tape->buf = NULL;
         }
 
         tape->chrdev_dir = IDETAPE_DIR_NONE;
@@ -1170,36 +878,44 @@ static void ide_tape_discard_merge_buffer(ide_drive_t *drive,
  * Generate a read/write request for the block device interface and wait for it
  * to be serviced.
  */
-static int idetape_queue_rw_tail(ide_drive_t *drive, int cmd, int blocks,
-                                 struct idetape_bh *bh)
+static int idetape_queue_rw_tail(ide_drive_t *drive, int cmd, int size)
 {
         idetape_tape_t *tape = drive->driver_data;
         struct request *rq;
-        int ret, errors;
+        int ret;
 
         debug_log(DBG_SENSE, "%s: cmd=%d\n", __func__, cmd);
+        BUG_ON(cmd != REQ_IDETAPE_READ && cmd != REQ_IDETAPE_WRITE);
+        BUG_ON(size < 0 || size % tape->blk_size);
 
         rq = blk_get_request(drive->queue, READ, __GFP_WAIT);
         rq->cmd_type = REQ_TYPE_SPECIAL;
         rq->cmd[13] = cmd;
         rq->rq_disk = tape->disk;
-        rq->special = (void *)bh;
-        rq->sector = tape->first_frame;
-        rq->nr_sectors = blocks;
-        rq->current_nr_sectors = blocks;
-        blk_execute_rq(drive->queue, tape->disk, rq, 0);
+        rq->__sector = tape->first_frame;
 
-        errors = rq->errors;
-        ret = tape->blk_size * (blocks - rq->current_nr_sectors);
-        blk_put_request(rq);
+        if (size) {
+                ret = blk_rq_map_kern(drive->queue, rq, tape->buf, size,
+                                      __GFP_WAIT);
+                if (ret)
+                        goto out_put;
+        }
 
-        if ((cmd & (REQ_IDETAPE_READ | REQ_IDETAPE_WRITE)) == 0)
-                return 0;
+        blk_execute_rq(drive->queue, tape->disk, rq, 0);
 
-        if (tape->merge_bh)
-                idetape_init_merge_buffer(tape);
-        if (errors == IDE_DRV_ERROR_GENERAL)
-                return -EIO;
+        /* calculate the number of transferred bytes and update buffer state */
+        size -= rq->resid_len;
+        tape->cur = tape->buf;
+        if (cmd == REQ_IDETAPE_READ)
+                tape->valid = size;
+        else
+                tape->valid = 0;
+
+        ret = size;
+        if (rq->errors == IDE_DRV_ERROR_GENERAL)
+                ret = -EIO;
+out_put:
+        blk_put_request(rq);
         return ret;
 }
 
@@ -1236,153 +952,87 @@ static void idetape_create_space_cmd(struct ide_atapi_pc *pc, int count, u8 cmd)
         pc->flags |= PC_FLAG_WAIT_FOR_DSC;
 }
 
-/* Queue up a character device originated write request. */
-static int idetape_add_chrdev_write_request(ide_drive_t *drive, int blocks)
-{
-        idetape_tape_t *tape = drive->driver_data;
-
-        debug_log(DBG_CHRDEV, "Enter %s\n", __func__);
-
-        return idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE,
-                                     blocks, tape->merge_bh);
-}
-
 static void ide_tape_flush_merge_buffer(ide_drive_t *drive)
 {
         idetape_tape_t *tape = drive->driver_data;
-        int blocks, min;
-        struct idetape_bh *bh;
 
         if (tape->chrdev_dir != IDETAPE_DIR_WRITE) {
                 printk(KERN_ERR "ide-tape: bug: Trying to empty merge buffer"
                                 " but we are not writing.\n");
                 return;
         }
-        if (tape->merge_bh_size > tape->buffer_size) {
-                printk(KERN_ERR "ide-tape: bug: merge_buffer too big\n");
-                tape->merge_bh_size = tape->buffer_size;
-        }
-        if (tape->merge_bh_size) {
-                blocks = tape->merge_bh_size / tape->blk_size;
-                if (tape->merge_bh_size % tape->blk_size) {
-                        unsigned int i;
-
-                        blocks++;
-                        i = tape->blk_size - tape->merge_bh_size %
-                                tape->blk_size;
-                        bh = tape->bh->b_reqnext;
-                        while (bh) {
-                                atomic_set(&bh->b_count, 0);
-                                bh = bh->b_reqnext;
-                        }
-                        bh = tape->bh;
-                        while (i) {
-                                if (bh == NULL) {
-                                        printk(KERN_INFO "ide-tape: bug,"
-                                                         " bh NULL\n");
-                                        break;
-                                }
-                                min = min(i, (unsigned int)(bh->b_size -
-                                                atomic_read(&bh->b_count)));
-                                memset(bh->b_data + atomic_read(&bh->b_count),
-                                                0, min);
-                                atomic_add(min, &bh->b_count);
-                                i -= min;
-                                bh = bh->b_reqnext;
-                        }
-                }
-                (void) idetape_add_chrdev_write_request(drive, blocks);
-                tape->merge_bh_size = 0;
-        }
-        if (tape->merge_bh != NULL) {
-                ide_tape_kfree_buffer(tape);
-                tape->merge_bh = NULL;
+        if (tape->buf) {
+                size_t aligned = roundup(tape->valid, tape->blk_size);
+
+                memset(tape->cur, 0, aligned - tape->valid);
+                idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, aligned);
+                kfree(tape->buf);
+                tape->buf = NULL;
         }
         tape->chrdev_dir = IDETAPE_DIR_NONE;
 }
 
-static int idetape_init_read(ide_drive_t *drive)
+static int idetape_init_rw(ide_drive_t *drive, int dir)
 {
         idetape_tape_t *tape = drive->driver_data;
-        int bytes_read;
-
-        /* Initialize read operation */
-        if (tape->chrdev_dir != IDETAPE_DIR_READ) {
-                if (tape->chrdev_dir == IDETAPE_DIR_WRITE) {
-                        ide_tape_flush_merge_buffer(drive);
-                        idetape_flush_tape_buffers(drive);
-                }
-                if (tape->merge_bh || tape->merge_bh_size) {
-                        printk(KERN_ERR "ide-tape: merge_bh_size should be"
-                                         " 0 now\n");
-                        tape->merge_bh_size = 0;
-                }
-                tape->merge_bh = ide_tape_kmalloc_buffer(tape, 0, 0);
-                if (!tape->merge_bh)
-                        return -ENOMEM;
-                tape->chrdev_dir = IDETAPE_DIR_READ;
+        int rc;
 
-                /*
-                 * Issue a read 0 command to ensure that DSC handshake is
-                 * switched from completion mode to buffer available mode.
-                 * No point in issuing this if DSC overlap isn't supported, some
-                 * drives (Seagate STT3401A) will return an error.
-                 */
-                if (drive->dev_flags & IDE_DFLAG_DSC_OVERLAP) {
-                        bytes_read = idetape_queue_rw_tail(drive,
-                                                        REQ_IDETAPE_READ, 0,
-                                                        tape->merge_bh);
-                        if (bytes_read < 0) {
-                                ide_tape_kfree_buffer(tape);
-                                tape->merge_bh = NULL;
-                                tape->chrdev_dir = IDETAPE_DIR_NONE;
-                                return bytes_read;
-                        }
-                }
-        }
+        BUG_ON(dir != IDETAPE_DIR_READ && dir != IDETAPE_DIR_WRITE);
 
-        return 0;
-}
+        if (tape->chrdev_dir == dir)
+                return 0;
 
-/* called from idetape_chrdev_read() to service a chrdev read request. */
-static int idetape_add_chrdev_read_request(ide_drive_t *drive, int blocks)
-{
-        idetape_tape_t *tape = drive->driver_data;
+        if (tape->chrdev_dir == IDETAPE_DIR_READ)
+                ide_tape_discard_merge_buffer(drive, 1);
+        else if (tape->chrdev_dir == IDETAPE_DIR_WRITE) {
+                ide_tape_flush_merge_buffer(drive);
+                idetape_flush_tape_buffers(drive);
+        }
 
-        debug_log(DBG_PROCS, "Enter %s, %d blocks\n", __func__, blocks);
+        if (tape->buf || tape->valid) {
+                printk(KERN_ERR "ide-tape: valid should be 0 now\n");
+                tape->valid = 0;
+        }
 
-        /* If we are at a filemark, return a read length of 0 */
-        if (test_bit(IDE_AFLAG_FILEMARK, &drive->atapi_flags))
-                return 0;
+        tape->buf = kmalloc(tape->buffer_size, GFP_KERNEL);
+        if (!tape->buf)
+                return -ENOMEM;
+        tape->chrdev_dir = dir;
+        tape->cur = tape->buf;
 
-        idetape_init_read(drive);
+        /*
+         * Issue a 0 rw command to ensure that DSC handshake is
+         * switched from completion mode to buffer available mode.  No
+         * point in issuing this if DSC overlap isn't supported, some
+         * drives (Seagate STT3401A) will return an error.
+         */
+        if (drive->dev_flags & IDE_DFLAG_DSC_OVERLAP) {
+                int cmd = dir == IDETAPE_DIR_READ ? REQ_IDETAPE_READ
+                                                  : REQ_IDETAPE_WRITE;
+
+                rc = idetape_queue_rw_tail(drive, cmd, 0);
+                if (rc < 0) {
+                        kfree(tape->buf);
+                        tape->buf = NULL;
+                        tape->chrdev_dir = IDETAPE_DIR_NONE;
+                        return rc;
+                }
+        }
 
-        return idetape_queue_rw_tail(drive, REQ_IDETAPE_READ, blocks,
-                                     tape->merge_bh);
+        return 0;
 }
 
 static void idetape_pad_zeros(ide_drive_t *drive, int bcount)
 {
         idetape_tape_t *tape = drive->driver_data;
-        struct idetape_bh *bh;
-        int blocks;
+
+        memset(tape->buf, 0, tape->buffer_size);
 
         while (bcount) {
-                unsigned int count;
+                unsigned int count = min(tape->buffer_size, bcount);
 
-                bh = tape->merge_bh;
-                count = min(tape->buffer_size, bcount);
+                idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, count);
                 bcount -= count;
-                blocks = count / tape->blk_size;
-                while (count) {
-                        atomic_set(&bh->b_count,
-                                   min(count, (unsigned int)bh->b_size));
-                        memset(bh->b_data, 0, atomic_read(&bh->b_count));
-                        count -= atomic_read(&bh->b_count);
-                        bh = bh->b_reqnext;
-                }
-                idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, blocks,
-                                      tape->merge_bh);
         }
 }
 
@@ -1462,7 +1112,7 @@ static int idetape_space_over_filemarks(ide_drive_t *drive, short mt_op,
         }
 
         if (tape->chrdev_dir == IDETAPE_DIR_READ) {
-                tape->merge_bh_size = 0;
+                tape->valid = 0;
                 if (test_and_clear_bit(IDE_AFLAG_FILEMARK, &drive->atapi_flags))
                         ++count;
                 ide_tape_discard_merge_buffer(drive, 0);
@@ -1511,9 +1161,9 @@ static ssize_t idetape_chrdev_read(struct file *file, char __user *buf,
 {
         struct ide_tape_obj *tape = file->private_data;
         ide_drive_t *drive = tape->drive;
-        ssize_t bytes_read, temp, actually_read = 0, rc;
+        size_t done = 0;
         ssize_t ret = 0;
-        u16 ctl = *(u16 *)&tape->caps[12];
+        int rc;
 
         debug_log(DBG_CHRDEV, "Enter %s, count %Zd\n", __func__, count);
 
@@ -1523,49 +1173,43 @@ static ssize_t idetape_chrdev_read(struct file *file, char __user *buf,
                             (count % tape->blk_size) == 0)
                                 tape->user_bs_factor = count / tape->blk_size;
         }
-        rc = idetape_init_read(drive);
+
+        rc = idetape_init_rw(drive, IDETAPE_DIR_READ);
         if (rc < 0)
                 return rc;
-        if (count == 0)
-                return (0);
-        if (tape->merge_bh_size) {
-                actually_read = min((unsigned int)(tape->merge_bh_size),
-                                    (unsigned int)count);
-                if (idetape_copy_stage_to_user(tape, buf, actually_read))
-                        ret = -EFAULT;
-                buf += actually_read;
-                tape->merge_bh_size -= actually_read;
-                count -= actually_read;
-        }
-        while (count >= tape->buffer_size) {
-                bytes_read = idetape_add_chrdev_read_request(drive, ctl);
-                if (bytes_read <= 0)
-                        goto finish;
-                if (idetape_copy_stage_to_user(tape, buf, bytes_read))
-                        ret = -EFAULT;
-                buf += bytes_read;
-                count -= bytes_read;
-                actually_read += bytes_read;
-        }
-        if (count) {
-                bytes_read = idetape_add_chrdev_read_request(drive, ctl);
-                if (bytes_read <= 0)
-                        goto finish;
-                temp = min((unsigned long)count, (unsigned long)bytes_read);
-                if (idetape_copy_stage_to_user(tape, buf, temp))
+
+        while (done < count) {
+                size_t todo;
+
+                /* refill if staging buffer is empty */
+                if (!tape->valid) {
+                        /* If we are at a filemark, nothing more to read */
+                        if (test_bit(IDE_AFLAG_FILEMARK, &drive->atapi_flags))
+                                break;
+                        /* read */
+                        if (idetape_queue_rw_tail(drive, REQ_IDETAPE_READ,
+                                                  tape->buffer_size) <= 0)
+                                break;
+                }
+
+                /* copy out */
+                todo = min_t(size_t, count - done, tape->valid);
+                if (copy_to_user(buf + done, tape->cur, todo))
                         ret = -EFAULT;
-                actually_read += temp;
-                tape->merge_bh_size = bytes_read-temp;
+
+                tape->cur += todo;
+                tape->valid -= todo;
+                done += todo;
         }
-finish:
-        if (!actually_read && test_bit(IDE_AFLAG_FILEMARK, &drive->atapi_flags)) {
+
+        if (!done && test_bit(IDE_AFLAG_FILEMARK, &drive->atapi_flags)) {
                 debug_log(DBG_SENSE, "%s: spacing over filemark\n", tape->name);
 
                 idetape_space_over_filemarks(drive, MTFSF, 1);
                 return 0;
         }
 
-        return ret ? ret : actually_read;
+        return ret ? ret : done;
 }
 
 static ssize_t idetape_chrdev_write(struct file *file, const char __user *buf,
@@ -1573,9 +1217,9 @@ static ssize_t idetape_chrdev_write(struct file *file, const char __user *buf,
 {
         struct ide_tape_obj *tape = file->private_data;
         ide_drive_t *drive = tape->drive;
-        ssize_t actually_written = 0;
+        size_t done = 0;
         ssize_t ret = 0;
-        u16 ctl = *(u16 *)&tape->caps[12];
+        int rc;
 
         /* The drive is write protected. */
         if (tape->write_prot)
@@ -1584,80 +1228,31 @@ static ssize_t idetape_chrdev_write(struct file *file, const char __user *buf,
         debug_log(DBG_CHRDEV, "Enter %s, count %Zd\n", __func__, count);
 
         /* Initialize write operation */
-        if (tape->chrdev_dir != IDETAPE_DIR_WRITE) {
-                if (tape->chrdev_dir == IDETAPE_DIR_READ)
-                        ide_tape_discard_merge_buffer(drive, 1);
-                if (tape->merge_bh || tape->merge_bh_size) {
-                        printk(KERN_ERR "ide-tape: merge_bh_size "
-                                "should be 0 now\n");
-                        tape->merge_bh_size = 0;
-                }
-                tape->merge_bh = ide_tape_kmalloc_buffer(tape, 0, 0);
-                if (!tape->merge_bh)
-                        return -ENOMEM;
-                tape->chrdev_dir = IDETAPE_DIR_WRITE;
-                idetape_init_merge_buffer(tape);
+        rc = idetape_init_rw(drive, IDETAPE_DIR_WRITE);
+        if (rc < 0)
+                return rc;
 
-                /*
-                 * Issue a write 0 command to ensure that DSC handshake is
-                 * switched from completion mode to buffer available mode. No
-                 * point in issuing this if DSC overlap isn't supported, some
-                 * drives (Seagate STT3401A) will return an error.
-                 */
-                if (drive->dev_flags & IDE_DFLAG_DSC_OVERLAP) {
-                        ssize_t retval = idetape_queue_rw_tail(drive,
-                                                        REQ_IDETAPE_WRITE, 0,
-                                                        tape->merge_bh);
-                        if (retval < 0) {
-                                ide_tape_kfree_buffer(tape);
-                                tape->merge_bh = NULL;
-                                tape->chrdev_dir = IDETAPE_DIR_NONE;
-                                return retval;
-                        }
-                }
-        }
-        if (count == 0)
-                return (0);
-        if (tape->merge_bh_size) {
-                if (tape->merge_bh_size >= tape->buffer_size) {
-                        printk(KERN_ERR "ide-tape: bug: merge buf too big\n");
-                        tape->merge_bh_size = 0;
-                }
-                actually_written = min((unsigned int)
-                                (tape->buffer_size - tape->merge_bh_size),
-                                (unsigned int)count);
-                if (idetape_copy_stage_from_user(tape, buf, actually_written))
-                                ret = -EFAULT;
-                buf += actually_written;
-                tape->merge_bh_size += actually_written;
-                count -= actually_written;
-
-                if (tape->merge_bh_size == tape->buffer_size) {
-                        ssize_t retval;
-                        tape->merge_bh_size = 0;
-                        retval = idetape_add_chrdev_write_request(drive, ctl);
-                        if (retval <= 0)
-                                return (retval);
-                }
-        }
-        while (count >= tape->buffer_size) {
-                ssize_t retval;
-                if (idetape_copy_stage_from_user(tape, buf, tape->buffer_size))
-                        ret = -EFAULT;
-                buf += tape->buffer_size;
-                count -= tape->buffer_size;
-                retval = idetape_add_chrdev_write_request(drive, ctl);
-                actually_written += tape->buffer_size;
-                if (retval <= 0)
-                        return (retval);
-        }
-        if (count) {
-                actually_written += count;
-                if (idetape_copy_stage_from_user(tape, buf, count))
+        while (done < count) {
+                size_t todo;
+
+                /* flush if staging buffer is full */
+                if (tape->valid == tape->buffer_size &&
+                    idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE,
+                                          tape->buffer_size) <= 0)
+                        return rc;
+
+                /* copy in */
+                todo = min_t(size_t, count - done,
+                             tape->buffer_size - tape->valid);
+                if (copy_from_user(tape->cur, buf + done, todo))
                         ret = -EFAULT;
-                tape->merge_bh_size += count;
+
+                tape->cur += todo;
+                tape->valid += todo;
+                done += todo;
         }
-        return ret ? ret : actually_written;
+
+        return ret ? ret : done;
 }
 
 static int idetape_write_filemark(ide_drive_t *drive)
@@ -1818,7 +1413,7 @@ static int idetape_chrdev_ioctl(struct inode *inode, struct file *file,
                 idetape_flush_tape_buffers(drive);
         }
         if (cmd == MTIOCGET || cmd == MTIOCPOS) {
-                block_offset = tape->merge_bh_size /
+                block_offset = tape->valid /
                         (tape->blk_size * tape->user_bs_factor);
                 position = idetape_read_position(drive);
                 if (position < 0)
@@ -1966,12 +1561,12 @@ static void idetape_write_release(ide_drive_t *drive, unsigned int minor)
         idetape_tape_t *tape = drive->driver_data;
 
         ide_tape_flush_merge_buffer(drive);
-        tape->merge_bh = ide_tape_kmalloc_buffer(tape, 1, 0);
-        if (tape->merge_bh != NULL) {
+        tape->buf = kmalloc(tape->buffer_size, GFP_KERNEL);
+        if (tape->buf != NULL) {
                 idetape_pad_zeros(drive, tape->blk_size *
                                 (tape->user_bs_factor - 1));
-                ide_tape_kfree_buffer(tape);
-                tape->merge_bh = NULL;
+                kfree(tape->buf);
+                tape->buf = NULL;
         }
         idetape_write_filemark(drive);
         idetape_flush_tape_buffers(drive);
@@ -2165,8 +1760,6 @@ static void idetape_setup(ide_drive_t *drive, idetape_tape_t *tape, int minor)
         u16 *ctl = (u16 *)&tape->caps[12];
 
         drive->pc_callback       = ide_tape_callback;
-        drive->pc_update_buffers = idetape_update_buffers;
-        drive->pc_io_buffers     = ide_tape_io_buffers;
 
         drive->dev_flags |= IDE_DFLAG_DSC_OVERLAP;
 
@@ -2197,11 +1790,6 @@ static void idetape_setup(ide_drive_t *drive, idetape_tape_t *tape, int minor)
                 tape->buffer_size = *ctl * tape->blk_size;
         }
         buffer_size = tape->buffer_size;
-        tape->pages_per_buffer = buffer_size / PAGE_SIZE;
-        if (buffer_size % PAGE_SIZE) {
-                tape->pages_per_buffer++;
-                tape->excess_bh_size = PAGE_SIZE - buffer_size % PAGE_SIZE;
-        }
 
         /* select the "best" DSC read/write polling freq */
         speed = max(*(u16 *)&tape->caps[14], *(u16 *)&tape->caps[8]);
@@ -2244,7 +1832,7 @@ static void ide_tape_release(struct device *dev)
         ide_drive_t *drive = tape->drive;
         struct gendisk *g = tape->disk;
 
-        BUG_ON(tape->merge_bh_size);
+        BUG_ON(tape->valid);
 
         drive->dev_flags &= ~IDE_DFLAG_DSC_OVERLAP;
         drive->driver_data = NULL;