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Subject[PATCH 05/10] ide-tape: kill idetape_bh
Date
Impact: kill now unnecessary idetape_bh

With everything using standard mechanisms, there is no need for
idetape_bh anymore. Kill it and use tape->buf, cur and valid to
describe data buffer instead.

Changes worth mentioning are...

* idetape_queue_rq_tail() now always queue tape->buf and and adjusts
buffer state properly before completion.

* idetape_pad_zeros() clears the buffer only once.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
drivers/ide/ide-tape.c | 296 +++++++++++++-----------------------------------
1 files changed, 81 insertions(+), 215 deletions(-)
diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index dd37fd7..e7f351b 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -131,12 +131,6 @@ enum {
IDETAPE_DIR_WRITE = (1 << 2),
};

-struct idetape_bh {
- u32 b_size;
- atomic_t b_count;
- char *b_data;
-};
-
/* Tape door status */
#define DOOR_UNLOCKED 0
#define DOOR_LOCKED 1
@@ -218,14 +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;
+ /* 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;
@@ -351,15 +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 *bh = tape->merge_bh;
-
- kfree(bh->b_data);
- kfree(bh);
-}
-
static void ide_tape_handle_dsc(ide_drive_t *);

static int ide_tape_callback(ide_drive_t *drive, int dsc)
@@ -605,7 +588,6 @@ 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;

ide_init_pc(pc);
@@ -618,14 +600,11 @@ static void ide_tape_create_rw_cmd(idetape_tape_t *tape,
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);
@@ -747,89 +726,6 @@ out:
}

/*
- * 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)
-{
- struct idetape_bh *bh;
-
- bh = kmalloc(sizeof(struct idetape_bh), GFP_KERNEL);
- if (!bh)
- return NULL;
-
- bh->b_data = kmalloc(tape->buffer_size, GFP_KERNEL);
- if (!bh->b_data) {
- kfree(bh);
- return NULL;
- }
-
- bh->b_size = tape->buffer_size;
- atomic_set(&bh->b_count, full ? bh->b_size : 0);
-
- return bh;
-}
-
-static int idetape_copy_stage_from_user(idetape_tape_t *tape,
- const char __user *buf, int n)
-{
- struct idetape_bh *bh = tape->bh;
- int ret = 0;
-
- if (n) {
- if (bh == NULL || n > bh->b_size - atomic_read(&bh->b_count)) {
- printk(KERN_ERR "ide-tape: bh == NULL in %s\n",
- __func__);
- return 1;
- }
- if (copy_from_user(bh->b_data + atomic_read(&bh->b_count), buf,
- n))
- ret = 1;
- atomic_add(n, &bh->b_count);
- if (atomic_read(&bh->b_count) == bh->b_size)
- tape->bh = NULL;
- }
-
- 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 ret = 0;
-
- if (n) {
- if (bh == NULL || n > tape->b_count) {
- printk(KERN_ERR "ide-tape: bh == NULL in %s\n",
- __func__);
- return 1;
- }
- if (copy_to_user(buf, tape->b_data, n))
- ret = 1;
- tape->b_data += n;
- tape->b_count -= n;
- if (!tape->b_count)
- tape->bh = NULL;
- }
- 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);
- }
-}
-
-/*
* Write a filemark if write_filemark=1. Flush the device buffers without
* writing a filemark otherwise.
*/
@@ -926,10 +822,10 @@ 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;
@@ -983,8 +879,7 @@ 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 blocks)
{
idetape_tape_t *tape = drive->driver_data;
size_t size = blocks * tape->blk_size;
@@ -1001,7 +896,7 @@ static int idetape_queue_rw_tail(ide_drive_t *drive, int cmd, int blocks,
rq->sector = tape->first_frame;

if (size) {
- ret = blk_rq_map_kern(drive->queue, rq, bh->b_data, size,
+ ret = blk_rq_map_kern(drive->queue, rq, tape->buf, size,
__GFP_WAIT);
if (ret)
goto out_put;
@@ -1009,17 +904,17 @@ static int idetape_queue_rw_tail(ide_drive_t *drive, int cmd, int blocks,

blk_execute_rq(drive->queue, tape->disk, rq, 0);

- /* calculate the number of transferred bytes and update bh */
+ /* calculate the number of transferred bytes and update buffer state */
size -= rq->data_len;
+ tape->cur = tape->buf;
if (cmd == REQ_IDETAPE_READ)
- atomic_add(size, &bh->b_count);
+ tape->valid = size;
+ else
+ tape->valid = 0;

ret = size;
if (rq->errors == IDE_DRV_ERROR_GENERAL)
ret = -EIO;
-
- if (tape->merge_bh)
- idetape_init_merge_buffer(tape);
out_put:
blk_put_request(rq);
return ret;
@@ -1061,49 +956,33 @@ static void idetape_create_space_cmd(struct ide_atapi_pc *pc, int count, u8 cmd)
/* 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);
+ return idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, blocks);
}

static void ide_tape_flush_merge_buffer(ide_drive_t *drive)
{
idetape_tape_t *tape = drive->driver_data;
int blocks;
- 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 = tape->blk_size -
- tape->merge_bh_size % tape->blk_size;
+ if (tape->buf) {
+ blocks = tape->valid / tape->blk_size;
+ if (tape->valid % tape->blk_size) {
blocks++;
- bh = tape->bh;
- if (bh) {
- memset(bh->b_data + atomic_read(&bh->b_count),
- 0, i);
- atomic_add(i, &bh->b_count);
- } else
- printk(KERN_INFO "ide-tape: bug, bh NULL\n");
+ memset(tape->buf + tape->valid, 0,
+ tape->blk_size - tape->valid % tape->blk_size);
}
(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 != NULL) {
+ kfree(tape->buf);
+ tape->buf = NULL;
}
tape->chrdev_dir = IDETAPE_DIR_NONE;
}
@@ -1119,15 +998,15 @@ static int idetape_init_read(ide_drive_t *drive)
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;
+ if (tape->buf || tape->valid) {
+ printk(KERN_ERR "ide-tape: valid should be 0 now\n");
+ tape->valid = 0;
}
- tape->merge_bh = ide_tape_kmalloc_buffer(tape, 0);
- if (!tape->merge_bh)
+ tape->buf = kmalloc(tape->buffer_size, GFP_KERNEL);
+ if (!tape->buf)
return -ENOMEM;
tape->chrdev_dir = IDETAPE_DIR_READ;
+ tape->cur = tape->buf;

/*
* Issue a read 0 command to ensure that DSC handshake is
@@ -1137,11 +1016,10 @@ static int idetape_init_read(ide_drive_t *drive)
*/
if (drive->dev_flags & IDE_DFLAG_DSC_OVERLAP) {
bytes_read = idetape_queue_rw_tail(drive,
- REQ_IDETAPE_READ, 0,
- tape->merge_bh);
+ REQ_IDETAPE_READ, 0);
if (bytes_read < 0) {
- ide_tape_kfree_buffer(tape);
- tape->merge_bh = NULL;
+ kfree(tape->buf);
+ tape->buf = NULL;
tape->chrdev_dir = IDETAPE_DIR_NONE;
return bytes_read;
}
@@ -1154,8 +1032,6 @@ static int idetape_init_read(ide_drive_t *drive)
/* 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;
-
debug_log(DBG_PROCS, "Enter %s, %d blocks\n", __func__, blocks);

/* If we are at a filemark, return a read length of 0 */
@@ -1164,27 +1040,21 @@ static int idetape_add_chrdev_read_request(ide_drive_t *drive, int blocks)

idetape_init_read(drive);

- return idetape_queue_rw_tail(drive, REQ_IDETAPE_READ, blocks,
- tape->merge_bh);
+ return idetape_queue_rw_tail(drive, REQ_IDETAPE_READ, blocks);
}

static void idetape_pad_zeros(ide_drive_t *drive, int bcount)
{
idetape_tape_t *tape = drive->driver_data;
- struct idetape_bh *bh = tape->merge_bh;
- int blocks;
+
+ memset(tape->buf, 0, tape->buffer_size);

while (bcount) {
- unsigned int count;
+ unsigned int count = min(tape->buffer_size, bcount);

- count = min(tape->buffer_size, bcount);
+ idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE,
+ count / tape->blk_size);
bcount -= count;
- blocks = count / tape->blk_size;
- atomic_set(&bh->b_count, count);
- memset(bh->b_data, 0, atomic_read(&bh->b_count));
-
- idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, blocks,
- tape->merge_bh);
}
}

@@ -1264,7 +1134,7 @@ 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);
@@ -1330,20 +1200,20 @@ static ssize_t idetape_chrdev_read(struct file *file, char __user *buf,
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))
+ 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;
- tape->merge_bh_size -= 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, ctl);
if (bytes_read <= 0)
goto finish;
- if (idetape_copy_stage_to_user(tape, buf, bytes_read))
+ if (copy_to_user(buf, tape->cur, bytes_read))
ret = -EFAULT;
buf += bytes_read;
count -= bytes_read;
@@ -1354,10 +1224,11 @@ static ssize_t idetape_chrdev_read(struct file *file, char __user *buf,
if (bytes_read <= 0)
goto finish;
temp = min((unsigned long)count, (unsigned long)bytes_read);
- if (idetape_copy_stage_to_user(tape, buf, temp))
+ if (copy_to_user(buf, tape->cur, temp))
ret = -EFAULT;
actually_read += temp;
- tape->merge_bh_size = bytes_read-temp;
+ tape->cur += temp;
+ tape->valid -= temp;
}
finish:
if (!actually_read && test_bit(IDE_AFLAG_FILEMARK, &drive->atapi_flags)) {
@@ -1389,16 +1260,15 @@ static ssize_t idetape_chrdev_write(struct file *file, const char __user *buf,
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;
+ if (tape->buf || tape->valid) {
+ printk(KERN_ERR "ide-tape: valid should be 0 now\n");
+ tape->valid = 0;
}
- tape->merge_bh = ide_tape_kmalloc_buffer(tape, 0);
- if (!tape->merge_bh)
+ tape->buf = kmalloc(tape->buffer_size, GFP_KERNEL);
+ if (!tape->buf)
return -ENOMEM;
tape->chrdev_dir = IDETAPE_DIR_WRITE;
- idetape_init_merge_buffer(tape);
+ tape->cur = tape->buf;

/*
* Issue a write 0 command to ensure that DSC handshake is
@@ -1408,11 +1278,10 @@ static ssize_t idetape_chrdev_write(struct file *file, const char __user *buf,
*/
if (drive->dev_flags & IDE_DFLAG_DSC_OVERLAP) {
ssize_t retval = idetape_queue_rw_tail(drive,
- REQ_IDETAPE_WRITE, 0,
- tape->merge_bh);
+ REQ_IDETAPE_WRITE, 0);
if (retval < 0) {
- ide_tape_kfree_buffer(tape);
- tape->merge_bh = NULL;
+ kfree(tape->buf);
+ tape->buf = NULL;
tape->chrdev_dir = IDETAPE_DIR_NONE;
return retval;
}
@@ -1420,23 +1289,19 @@ static ssize_t idetape_chrdev_write(struct file *file, const char __user *buf,
}
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;
+ 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;
- tape->merge_bh_size += actually_written;
count -= actually_written;
+ tape->cur += actually_written;
+ tape->valid += actually_written;

- if (tape->merge_bh_size == tape->buffer_size) {
+ if (tape->valid == tape->buffer_size) {
ssize_t retval;
- tape->merge_bh_size = 0;
retval = idetape_add_chrdev_write_request(drive, ctl);
if (retval <= 0)
return (retval);
@@ -1444,7 +1309,7 @@ static ssize_t idetape_chrdev_write(struct file *file, const char __user *buf,
}
while (count >= tape->buffer_size) {
ssize_t retval;
- if (idetape_copy_stage_from_user(tape, buf, tape->buffer_size))
+ if (copy_from_user(tape->cur, buf, tape->buffer_size))
ret = -EFAULT;
buf += tape->buffer_size;
count -= tape->buffer_size;
@@ -1455,9 +1320,10 @@ static ssize_t idetape_chrdev_write(struct file *file, const char __user *buf,
}
if (count) {
actually_written += count;
- if (idetape_copy_stage_from_user(tape, buf, count))
+ if (copy_from_user(tape->cur, buf, count))
ret = -EFAULT;
- tape->merge_bh_size += count;
+ tape->cur += count;
+ tape->valid += count;
}
return ret ? ret : actually_written;
}
@@ -1620,7 +1486,7 @@ 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)
@@ -1768,12 +1634,12 @@ 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);
- 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);
@@ -2039,7 +1905,7 @@ 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;
--
1.6.0.2


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