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Subject[PATCH 08/10] ide-tape: simplify read/write functions
Date
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>
---
drivers/ide/ide-tape.c | 149 ++++++++++++++++--------------------------------
1 files changed, 50 insertions(+), 99 deletions(-)
diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index 5fc3282..95e9131 100644
--- 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 + tape->valid, 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;
}
@@ -1027,20 +1019,6 @@ 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;
@@ -1180,8 +1158,9 @@ 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);

@@ -1191,52 +1170,43 @@ 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,
@@ -1244,7 +1214,7 @@ 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;

@@ -1258,47 +1228,28 @@ 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)
--
1.6.0.2


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