ide-tape: simplify read/write functions

Impact: cleanup

idetape_chrdev_read/write() functions are unnecessarily complex when
everything can be handled in a single loop.  Collapse
idetape_add_chrdev_read/write_request() into the rw functions and
simplify the implementation.

Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index d5e9bb286e306b990d2992db13439f2895a7d3f0..2599579e4174dee02e0e61351a6823476a3ccfcd 100644 (file)
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -953,14 +953,6 @@ 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 size)
-{
-       debug_log(DBG_CHRDEV, "Enter %s\n", __func__);
-
-       return idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, size);
-}
-
 static void ide_tape_flush_merge_buffer(ide_drive_t *drive)
 {
        idetape_tape_t *tape = drive->driver_data;
@@ -974,7 +966,7 @@ static void ide_tape_flush_merge_buffer(ide_drive_t *drive)
                size_t aligned = roundup(tape->valid, tape->blk_size);
 
                memset(tape->cur, 0, aligned - tape->valid);
-               idetape_add_chrdev_write_request(drive, aligned);
+               idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, aligned);
                kfree(tape->buf);
                tape->buf = NULL;
        }
@@ -1031,20 +1023,6 @@ static int idetape_init_rw(ide_drive_t *drive, int 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 size)
-{
-       debug_log(DBG_PROCS, "Enter %s, %d bytes\n", __func__, size);
-
-       /* If we are at a filemark, return a read length of 0 */
-       if (test_bit(IDE_AFLAG_FILEMARK, &drive->atapi_flags))
-               return 0;
-
-       idetape_init_rw(drive, IDETAPE_DIR_READ);
-
-       return idetape_queue_rw_tail(drive, REQ_IDETAPE_READ, size);
-}
-
 static void idetape_pad_zeros(ide_drive_t *drive, int bcount)
 {
        idetape_tape_t *tape = drive->driver_data;
@@ -1184,8 +1162,9 @@ 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;
+       int rc;
 
        debug_log(DBG_CHRDEV, "Enter %s, count %Zd\n", __func__, count);
 
@@ -1195,52 +1174,43 @@ 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_rw(drive, IDETAPE_DIR_READ);
        if (rc < 0)
                return rc;
-       if (count == 0)
-               return (0);
-       if (tape->valid) {
-               actually_read = min_t(unsigned int, tape->valid, count);
-               if (copy_to_user(buf, tape->cur, actually_read))
-                       ret = -EFAULT;
-               buf += actually_read;
-               count -= actually_read;
-               tape->cur += actually_read;
-               tape->valid -= actually_read;
-       }
-       while (count >= tape->buffer_size) {
-               bytes_read = idetape_add_chrdev_read_request(drive,
-                                                            tape->buffer_size);
-               if (bytes_read <= 0)
-                       goto finish;
-               if (copy_to_user(buf, tape->cur, bytes_read))
-                       ret = -EFAULT;
-               buf += bytes_read;
-               count -= bytes_read;
-               actually_read += bytes_read;
-       }
-       if (count) {
-               bytes_read = idetape_add_chrdev_read_request(drive,
-                                                            tape->buffer_size);
-               if (bytes_read <= 0)
-                       goto finish;
-               temp = min((unsigned long)count, (unsigned long)bytes_read);
-               if (copy_to_user(buf, tape->cur, 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->cur += temp;
-               tape->valid -= 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,
@@ -1248,7 +1218,7 @@ 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;
        int rc;
 
@@ -1262,47 +1232,28 @@ static ssize_t idetape_chrdev_write(struct file *file, const char __user *buf,
        rc = idetape_init_rw(drive, IDETAPE_DIR_WRITE);
        if (rc < 0)
                return rc;
-       if (count == 0)
-               return (0);
-       if (tape->valid < tape->buffer_size) {
-               actually_written = min_t(unsigned int,
-                                        tape->buffer_size - tape->valid,
-                                        count);
-               if (copy_from_user(tape->cur, buf, actually_written))
-                       ret = -EFAULT;
-               buf += actually_written;
-               count -= actually_written;
-               tape->cur += actually_written;
-               tape->valid += actually_written;
-
-               if (tape->valid == tape->buffer_size) {
-                       ssize_t retval;
-                       retval = idetape_add_chrdev_write_request(drive,
-                                                       tape->buffer_size);
-                       if (retval <= 0)
-                               return (retval);
-               }
-       }
-       while (count >= tape->buffer_size) {
-               ssize_t retval;
-               if (copy_from_user(tape->cur, buf, tape->buffer_size))
-                       ret = -EFAULT;
-               buf += tape->buffer_size;
-               count -= tape->buffer_size;
-               retval = idetape_add_chrdev_write_request(drive,
-                                                         tape->buffer_size);
-               actually_written += tape->buffer_size;
-               if (retval <= 0)
-                       return (retval);
-       }
-       if (count) {
-               actually_written += count;
-               if (copy_from_user(tape->cur, 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->cur += count;
-               tape->valid += 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)