[PATCH 0/6] ide-tape: refit tape data buffer bits/kill pipelining-v2

[PATCH 0/6] ide-tape: refit tape data buffer bits/kill pipelining-v2

[Borislav Petkov]

Hi Bart,

here's another patchset that contains some other fixes along with the changes
you suggested. We have now a tape->merge_bh buffer which is a singly linked list
of bh's and tape->bh is a pointer within that list. The remaining pipelining
functions have been readjusted to handle the merge buffer. I guess, that was it,
pipelining is gone.

 drivers/ide/ide-tape.c |  215 ++++++++++++++++++++++--------------------------
 1 files changed, 99 insertions(+), 116 deletions(-)

[PATCH 1/6] ide-tape: make __idetape_discard_read_pipeline() of type void

[Borislav Petkov]

It always returns 0 which has no effect on tape positioning calculation so
simplify it by converting its type to void, bringing no functional change to the
driver.

Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
---
 drivers/ide/ide-tape.c |   11 ++++-------
 1 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index 970f25f..0cd0684 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -1641,12 +1641,12 @@ static int idetape_create_prevent_cmd(ide_drive_t *drive,
 	return 1;
 }
 
-static int __idetape_discard_read_pipeline(ide_drive_t *drive)
+static void __idetape_discard_read_pipeline(ide_drive_t *drive)
 {
 	idetape_tape_t *tape = drive->driver_data;
 
 	if (tape->chrdev_dir != IDETAPE_DIR_READ)
-		return 0;
+		return;
 
 	clear_bit(IDETAPE_FLAG_FILEMARK, &tape->flags);
 	tape->merge_stage_size = 0;
@@ -1656,8 +1656,6 @@ static int __idetape_discard_read_pipeline(ide_drive_t *drive)
 	}
 
 	tape->chrdev_dir = IDETAPE_DIR_NONE;
-
-	return 0;
 }
 
 /*
@@ -1689,13 +1687,12 @@ static void idetape_discard_read_pipeline(ide_drive_t *drive,
 					  int restore_position)
 {
 	idetape_tape_t *tape = drive->driver_data;
-	int cnt;
 	int seek, position;
 
-	cnt = __idetape_discard_read_pipeline(drive);
+	__idetape_discard_read_pipeline(drive);
 	if (restore_position) {
 		position = idetape_read_position(drive);
-		seek = position > cnt ? position - cnt : 0;
+		seek = position > 0 ? position : 0;
 		if (idetape_position_tape(drive, seek, 0, 0)) {
 			printk(KERN_INFO "ide-tape: %s: position_tape failed in"
 					 " discard_pipeline()\n", tape->name);
-- 
1.5.4.1

[PATCH 2/6] ide-tape: mv idetape_discard_read_pipeline ide_tape_discard_merge_buffer

[Borislav Petkov]

Also, rename its __-low level helper too.

Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
---
 drivers/ide/ide-tape.c |   34 +++++++++++++++++-----------------
 1 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index 0cd0684..ecc11c1 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -1641,7 +1641,7 @@ static int idetape_create_prevent_cmd(ide_drive_t *drive,
 	return 1;
 }
 
-static void __idetape_discard_read_pipeline(ide_drive_t *drive)
+static void __ide_tape_discard_merge_buffer(ide_drive_t *drive)
 {
 	idetape_tape_t *tape = drive->driver_data;
 
@@ -1672,7 +1672,7 @@ static int idetape_position_tape(ide_drive_t *drive, unsigned int block,
 	struct ide_atapi_pc pc;
 
 	if (tape->chrdev_dir == IDETAPE_DIR_READ)
-		__idetape_discard_read_pipeline(drive);
+		__ide_tape_discard_merge_buffer(drive);
 	idetape_wait_ready(drive, 60 * 5 * HZ);
 	idetape_create_locate_cmd(drive, &pc, block, partition, skip);
 	retval = idetape_queue_pc_tail(drive, &pc);
@@ -1683,19 +1683,19 @@ static int idetape_position_tape(ide_drive_t *drive, unsigned int block,
 	return (idetape_queue_pc_tail(drive, &pc));
 }
 
-static void idetape_discard_read_pipeline(ide_drive_t *drive,
+static void ide_tape_discard_merge_buffer(ide_drive_t *drive,
 					  int restore_position)
 {
 	idetape_tape_t *tape = drive->driver_data;
 	int seek, position;
 
-	__idetape_discard_read_pipeline(drive);
+	__ide_tape_discard_merge_buffer(drive);
 	if (restore_position) {
 		position = idetape_read_position(drive);
 		seek = position > 0 ? position : 0;
 		if (idetape_position_tape(drive, seek, 0, 0)) {
 			printk(KERN_INFO "ide-tape: %s: position_tape failed in"
-					 " discard_pipeline()\n", tape->name);
+					 " %s\n", tape->name, __func__);
 			return;
 		}
 	}
@@ -1996,7 +1996,7 @@ static int idetape_space_over_filemarks(ide_drive_t *drive, short mt_op,
 		tape->merge_stage_size = 0;
 		if (test_and_clear_bit(IDETAPE_FLAG_FILEMARK, &tape->flags))
 			++count;
-		idetape_discard_read_pipeline(drive, 0);
+		ide_tape_discard_merge_buffer(drive, 0);
 	}
 
 	/*
@@ -2121,7 +2121,7 @@ static ssize_t idetape_chrdev_write(struct file *file, const char __user *buf,
 	/* Initialize write operation */
 	if (tape->chrdev_dir != IDETAPE_DIR_WRITE) {
 		if (tape->chrdev_dir == IDETAPE_DIR_READ)
-			idetape_discard_read_pipeline(drive, 1);
+			ide_tape_discard_merge_buffer(drive, 1);
 		if (tape->merge_stage || tape->merge_stage_size) {
 			printk(KERN_ERR "ide-tape: merge_stage_size "
 				"should be 0 now\n");
@@ -2246,7 +2246,7 @@ static int idetape_mtioctop(ide_drive_t *drive, short mt_op, int mt_count)
 	case MTWEOF:
 		if (tape->write_prot)
 			return -EACCES;
-		idetape_discard_read_pipeline(drive, 1);
+		ide_tape_discard_merge_buffer(drive, 1);
 		for (i = 0; i < mt_count; i++) {
 			retval = idetape_write_filemark(drive);
 			if (retval)
@@ -2254,12 +2254,12 @@ static int idetape_mtioctop(ide_drive_t *drive, short mt_op, int mt_count)
 		}
 		return 0;
 	case MTREW:
-		idetape_discard_read_pipeline(drive, 0);
+		ide_tape_discard_merge_buffer(drive, 0);
 		if (idetape_rewind_tape(drive))
 			return -EIO;
 		return 0;
 	case MTLOAD:
-		idetape_discard_read_pipeline(drive, 0);
+		ide_tape_discard_merge_buffer(drive, 0);
 		idetape_create_load_unload_cmd(drive, &pc,
 					       IDETAPE_LU_LOAD_MASK);
 		return idetape_queue_pc_tail(drive, &pc);
@@ -2274,7 +2274,7 @@ static int idetape_mtioctop(ide_drive_t *drive, short mt_op, int mt_count)
 				if (!idetape_queue_pc_tail(drive, &pc))
 					tape->door_locked = DOOR_UNLOCKED;
 		}
-		idetape_discard_read_pipeline(drive, 0);
+		ide_tape_discard_merge_buffer(drive, 0);
 		idetape_create_load_unload_cmd(drive, &pc,
 					      !IDETAPE_LU_LOAD_MASK);
 		retval = idetape_queue_pc_tail(drive, &pc);
@@ -2282,10 +2282,10 @@ static int idetape_mtioctop(ide_drive_t *drive, short mt_op, int mt_count)
 			clear_bit(IDETAPE_FLAG_MEDIUM_PRESENT, &tape->flags);
 		return retval;
 	case MTNOP:
-		idetape_discard_read_pipeline(drive, 0);
+		ide_tape_discard_merge_buffer(drive, 0);
 		return idetape_flush_tape_buffers(drive);
 	case MTRETEN:
-		idetape_discard_read_pipeline(drive, 0);
+		ide_tape_discard_merge_buffer(drive, 0);
 		idetape_create_load_unload_cmd(drive, &pc,
 			IDETAPE_LU_RETENSION_MASK | IDETAPE_LU_LOAD_MASK);
 		return idetape_queue_pc_tail(drive, &pc);
@@ -2307,11 +2307,11 @@ static int idetape_mtioctop(ide_drive_t *drive, short mt_op, int mt_count)
 			set_bit(IDETAPE_FLAG_DETECT_BS, &tape->flags);
 		return 0;
 	case MTSEEK:
-		idetape_discard_read_pipeline(drive, 0);
+		ide_tape_discard_merge_buffer(drive, 0);
 		return idetape_position_tape(drive,
 			mt_count * tape->user_bs_factor, tape->partition, 0);
 	case MTSETPART:
-		idetape_discard_read_pipeline(drive, 0);
+		ide_tape_discard_merge_buffer(drive, 0);
 		return idetape_position_tape(drive, 0, mt_count, 0);
 	case MTFSR:
 	case MTBSR:
@@ -2393,7 +2393,7 @@ static int idetape_chrdev_ioctl(struct inode *inode, struct file *file,
 		return 0;
 	default:
 		if (tape->chrdev_dir == IDETAPE_DIR_READ)
-			idetape_discard_read_pipeline(drive, 1);
+			ide_tape_discard_merge_buffer(drive, 1);
 		return idetape_blkdev_ioctl(drive, cmd, arg);
 	}
 }
@@ -2535,7 +2535,7 @@ static int idetape_chrdev_release(struct inode *inode, struct file *filp)
 		idetape_write_release(drive, minor);
 	if (tape->chrdev_dir == IDETAPE_DIR_READ) {
 		if (minor < 128)
-			idetape_discard_read_pipeline(drive, 1);
+			ide_tape_discard_merge_buffer(drive, 1);
 	}
 
 	if (minor < 128 && test_bit(IDETAPE_FLAG_MEDIUM_PRESENT, &tape->flags))
-- 
1.5.4.1

[PATCH 3/6] ide-tape: mv idetape_empty_write_pipeline ide_tape_flush_merge_buffer

[Borislav Petkov]

Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
---
 drivers/ide/ide-tape.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index ecc11c1..d5ca673 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -1779,7 +1779,7 @@ static int idetape_add_chrdev_write_request(ide_drive_t *drive, int blocks)
 				     blocks, tape->merge_stage->bh);
 }
 
-static void idetape_empty_write_pipeline(ide_drive_t *drive)
+static void ide_tape_flush_merge_buffer(ide_drive_t *drive)
 {
 	idetape_tape_t *tape = drive->driver_data;
 	int blocks, min;
@@ -1841,7 +1841,7 @@ static int idetape_init_read(ide_drive_t *drive)
 	/* Initialize read operation */
 	if (tape->chrdev_dir != IDETAPE_DIR_READ) {
 		if (tape->chrdev_dir == IDETAPE_DIR_WRITE) {
-			idetape_empty_write_pipeline(drive);
+			ide_tape_flush_merge_buffer(drive);
 			idetape_flush_tape_buffers(drive);
 		}
 		if (tape->merge_stage || tape->merge_stage_size) {
@@ -2357,7 +2357,7 @@ static int idetape_chrdev_ioctl(struct inode *inode, struct file *file,
 	debug_log(DBG_CHRDEV, "Enter %s, cmd=%u\n", __func__, cmd);
 
 	if (tape->chrdev_dir == IDETAPE_DIR_WRITE) {
-		idetape_empty_write_pipeline(drive);
+		ide_tape_flush_merge_buffer(drive);
 		idetape_flush_tape_buffers(drive);
 	}
 	if (cmd == MTIOCGET || cmd == MTIOCPOS) {
@@ -2506,7 +2506,7 @@ static void idetape_write_release(ide_drive_t *drive, unsigned int minor)
 {
 	idetape_tape_t *tape = drive->driver_data;
 
-	idetape_empty_write_pipeline(drive);
+	ide_tape_flush_merge_buffer(drive);
 	tape->merge_stage = ide_tape_kmalloc_buffer(tape, 1, 0);
 	if (tape->merge_stage != NULL) {
 		idetape_pad_zeros(drive, tape->blk_size *
-- 
1.5.4.1

[PATCH 4/6] ide-tape: mv tape->merge_stage_size tape->merge_bh_size

[Borislav Petkov]

This is the size of the merge buffer.

Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
---
 drivers/ide/ide-tape.c |   61 ++++++++++++++++++++++++-----------------------
 1 files changed, 31 insertions(+), 30 deletions(-)

diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index d5ca673..d7fee6e 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -310,7 +310,8 @@ typedef struct ide_tape_obj {
 	/* Data buffer size chosen based on the tape's recommendation */
 	int buffer_size;
 	idetape_stage_t *merge_stage;
-	int merge_stage_size;
+	/* size of the merge buffer */
+	int merge_bh_size;
 	struct idetape_bh *bh;
 	char *b_data;
 	int b_count;
@@ -1649,7 +1650,7 @@ static void __ide_tape_discard_merge_buffer(ide_drive_t *drive)
 		return;
 
 	clear_bit(IDETAPE_FLAG_FILEMARK, &tape->flags);
-	tape->merge_stage_size = 0;
+	tape->merge_bh_size = 0;
 	if (tape->merge_stage != NULL) {
 		ide_tape_kfree_buffer(tape->merge_stage);
 		tape->merge_stage = NULL;
@@ -1790,17 +1791,17 @@ static void ide_tape_flush_merge_buffer(ide_drive_t *drive)
 				" but we are not writing.\n");
 		return;
 	}
-	if (tape->merge_stage_size > tape->buffer_size) {
+	if (tape->merge_bh_size > tape->buffer_size) {
 		printk(KERN_ERR "ide-tape: bug: merge_buffer too big\n");
-		tape->merge_stage_size = tape->buffer_size;
+		tape->merge_bh_size = tape->buffer_size;
 	}
-	if (tape->merge_stage_size) {
-		blocks = tape->merge_stage_size / tape->blk_size;
-		if (tape->merge_stage_size % tape->blk_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_stage_size %
+			i = tape->blk_size - tape->merge_bh_size %
 				tape->blk_size;
 			bh = tape->bh->b_reqnext;
 			while (bh) {
@@ -1824,7 +1825,7 @@ static void ide_tape_flush_merge_buffer(ide_drive_t *drive)
 			}
 		}
 		(void) idetape_add_chrdev_write_request(drive, blocks);
-		tape->merge_stage_size = 0;
+		tape->merge_bh_size = 0;
 	}
 	if (tape->merge_stage != NULL) {
 		ide_tape_kfree_buffer(tape->merge_stage);
@@ -1844,10 +1845,10 @@ static int idetape_init_read(ide_drive_t *drive)
 			ide_tape_flush_merge_buffer(drive);
 			idetape_flush_tape_buffers(drive);
 		}
-		if (tape->merge_stage || tape->merge_stage_size) {
-			printk(KERN_ERR "ide-tape: merge_stage_size should be"
+		if (tape->merge_stage || tape->merge_bh_size) {
+			printk(KERN_ERR "ide-tape: merge_bh_size should be"
 					 " 0 now\n");
-			tape->merge_stage_size = 0;
+			tape->merge_bh_size = 0;
 		}
 		tape->merge_stage = ide_tape_kmalloc_buffer(tape, 0, 0);
 		if (!tape->merge_stage)
@@ -1993,7 +1994,7 @@ static int idetape_space_over_filemarks(ide_drive_t *drive, short mt_op,
 	}
 
 	if (tape->chrdev_dir == IDETAPE_DIR_READ) {
-		tape->merge_stage_size = 0;
+		tape->merge_bh_size = 0;
 		if (test_and_clear_bit(IDETAPE_FLAG_FILEMARK, &tape->flags))
 			++count;
 		ide_tape_discard_merge_buffer(drive, 0);
@@ -2063,13 +2064,13 @@ static ssize_t idetape_chrdev_read(struct file *file, char __user *buf,
 		return rc;
 	if (count == 0)
 		return (0);
-	if (tape->merge_stage_size) {
-		actually_read = min((unsigned int)(tape->merge_stage_size),
+	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_stage_size -= actually_read;
+		tape->merge_bh_size -= actually_read;
 		count -= actually_read;
 	}
 	while (count >= tape->buffer_size) {
@@ -2090,7 +2091,7 @@ static ssize_t idetape_chrdev_read(struct file *file, char __user *buf,
 		if (idetape_copy_stage_to_user(tape, buf, temp))
 			ret = -EFAULT;
 		actually_read += temp;
-		tape->merge_stage_size = bytes_read-temp;
+		tape->merge_bh_size = bytes_read-temp;
 	}
 finish:
 	if (!actually_read && test_bit(IDETAPE_FLAG_FILEMARK, &tape->flags)) {
@@ -2122,10 +2123,10 @@ 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_stage || tape->merge_stage_size) {
-			printk(KERN_ERR "ide-tape: merge_stage_size "
+		if (tape->merge_stage || tape->merge_bh_size) {
+			printk(KERN_ERR "ide-tape: merge_bh_size "
 				"should be 0 now\n");
-			tape->merge_stage_size = 0;
+			tape->merge_bh_size = 0;
 		}
 		tape->merge_stage = ide_tape_kmalloc_buffer(tape, 0, 0);
 		if (!tape->merge_stage)
@@ -2153,23 +2154,23 @@ static ssize_t idetape_chrdev_write(struct file *file, const char __user *buf,
 	}
 	if (count == 0)
 		return (0);
-	if (tape->merge_stage_size) {
-		if (tape->merge_stage_size >= tape->buffer_size) {
+	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_stage_size = 0;
+			tape->merge_bh_size = 0;
 		}
 		actually_written = min((unsigned int)
-				(tape->buffer_size - tape->merge_stage_size),
+				(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_stage_size += actually_written;
+		tape->merge_bh_size += actually_written;
 		count -= actually_written;
 
-		if (tape->merge_stage_size == tape->buffer_size) {
+		if (tape->merge_bh_size == tape->buffer_size) {
 			ssize_t retval;
-			tape->merge_stage_size = 0;
+			tape->merge_bh_size = 0;
 			retval = idetape_add_chrdev_write_request(drive, ctl);
 			if (retval <= 0)
 				return (retval);
@@ -2190,7 +2191,7 @@ static ssize_t idetape_chrdev_write(struct file *file, const char __user *buf,
 		actually_written += count;
 		if (idetape_copy_stage_from_user(tape, buf, count))
 			ret = -EFAULT;
-		tape->merge_stage_size += count;
+		tape->merge_bh_size += count;
 	}
 	return ret ? ret : actually_written;
 }
@@ -2361,7 +2362,7 @@ 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_stage_size /
+		block_offset = tape->merge_bh_size /
 			(tape->blk_size * tape->user_bs_factor);
 		position = idetape_read_position(drive);
 		if (position < 0)
@@ -2790,7 +2791,7 @@ static void ide_tape_release(struct kref *kref)
 	ide_drive_t *drive = tape->drive;
 	struct gendisk *g = tape->disk;
 
-	BUG_ON(tape->merge_stage_size);
+	BUG_ON(tape->merge_bh_size);
 
 	drive->dsc_overlap = 0;
 	drive->driver_data = NULL;
-- 
1.5.4.1

[PATCH 5/6] ide-tape: remove tape->merge_stage

[Borislav Petkov]

Get rid of the pipeline merge stage but retain the chrdev req caching
functionality by using a merge buffer tape->merge_bh which is flushed in chunks
of several blocks at a time. Also, remove last references to pipelining, e.g.
typedef idetape_stage_s.

Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
---
 drivers/ide/ide-tape.c |  107 ++++++++++++++++++++---------------------------
 1 files changed, 46 insertions(+), 61 deletions(-)

diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index d7fee6e..78a76a0 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -215,13 +215,6 @@ enum {
 	IDETAPE_FLAG_MEDIUM_PRESENT	= (1 << 6),
 };
 
-/* A pipeline stage. */
-typedef struct idetape_stage_s {
-	struct request rq;			/* The corresponding request */
-	struct idetape_bh *bh;			/* The data buffers */
-	struct idetape_stage_s *next;		/* Pointer to the next stage */
-} idetape_stage_t;
-
 /*
  * Most of our global data which we need to save even as we leave the driver due
  * to an interrupt or a timer event is stored in the struct defined below.
@@ -309,9 +302,11 @@ typedef struct ide_tape_obj {
 
 	/* Data buffer size chosen based on the tape's recommendation */
 	int buffer_size;
-	idetape_stage_t *merge_stage;
+	/* 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;
@@ -585,9 +580,9 @@ static void idetape_analyze_error(ide_drive_t *drive, u8 *sense)
 }
 
 /* Free data buffers completely. */
-static void ide_tape_kfree_buffer(idetape_stage_t *stage)
+static void ide_tape_kfree_buffer(idetape_tape_t *tape)
 {
-	struct idetape_bh *prev_bh, *bh = stage->bh;
+	struct idetape_bh *prev_bh, *bh = tape->merge_bh;
 
 	while (bh) {
 		u32 size = bh->b_size;
@@ -605,7 +600,7 @@ static void ide_tape_kfree_buffer(idetape_stage_t *stage)
 		bh = bh->b_reqnext;
 		kfree(prev_bh);
 	}
-	kfree(stage);
+	kfree(tape->merge_bh);
 }
 
 static int idetape_end_request(ide_drive_t *drive, int uptodate, int nr_sects)
@@ -1299,22 +1294,16 @@ out:
  * It returns a pointer to the newly allocated buffer, or NULL in case of
  * failure.
  */
-static idetape_stage_t *ide_tape_kmalloc_buffer(idetape_tape_t *tape, int full,
-						int clear)
+static struct idetape_bh *ide_tape_kmalloc_buffer(idetape_tape_t *tape,
+						  int full, int clear)
 {
-	idetape_stage_t *stage;
-	struct idetape_bh *prev_bh, *bh;
+	struct idetape_bh *prev_bh, *bh, *merge_bh;
 	int pages = tape->pages_per_buffer;
 	unsigned int order, b_allocd;
 	char *b_data = NULL;
 
-	stage = kmalloc(sizeof(idetape_stage_t), GFP_KERNEL);
-	if (!stage)
-		return NULL;
-	stage->next = NULL;
-
-	stage->bh = kmalloc(sizeof(struct idetape_bh), GFP_KERNEL);
-	bh = stage->bh;
+	merge_bh = kmalloc(sizeof(struct idetape_bh), GFP_KERNEL);
+	bh = merge_bh;
 	if (bh == NULL)
 		goto abort;
 
@@ -1374,9 +1363,9 @@ static idetape_stage_t *ide_tape_kmalloc_buffer(idetape_tape_t *tape, int full,
 	bh->b_size -= tape->excess_bh_size;
 	if (full)
 		atomic_sub(tape->excess_bh_size, &bh->b_count);
-	return stage;
+	return merge_bh;
 abort:
-	ide_tape_kfree_buffer(stage);
+	ide_tape_kfree_buffer(tape);
 	return NULL;
 }
 
@@ -1444,11 +1433,11 @@ static int idetape_copy_stage_to_user(idetape_tape_t *tape, char __user *buf,
 	return ret;
 }
 
-static void idetape_init_merge_stage(idetape_tape_t *tape)
+static void idetape_init_merge_buffer(idetape_tape_t *tape)
 {
-	struct idetape_bh *bh = tape->merge_stage->bh;
+	struct idetape_bh *bh = tape->merge_bh;
+	tape->bh = tape->merge_bh;
 
-	tape->bh = bh;
 	if (tape->chrdev_dir == IDETAPE_DIR_WRITE)
 		atomic_set(&bh->b_count, 0);
 	else {
@@ -1651,9 +1640,9 @@ static void __ide_tape_discard_merge_buffer(ide_drive_t *drive)
 
 	clear_bit(IDETAPE_FLAG_FILEMARK, &tape->flags);
 	tape->merge_bh_size = 0;
-	if (tape->merge_stage != NULL) {
-		ide_tape_kfree_buffer(tape->merge_stage);
-		tape->merge_stage = NULL;
+	if (tape->merge_bh != NULL) {
+		ide_tape_kfree_buffer(tape);
+		tape->merge_bh = NULL;
 	}
 
 	tape->chrdev_dir = IDETAPE_DIR_NONE;
@@ -1725,8 +1714,8 @@ static int idetape_queue_rw_tail(ide_drive_t *drive, int cmd, int blocks,
 	if ((cmd & (REQ_IDETAPE_READ | REQ_IDETAPE_WRITE)) == 0)
 		return 0;
 
-	if (tape->merge_stage)
-		idetape_init_merge_stage(tape);
+	if (tape->merge_bh)
+		idetape_init_merge_buffer(tape);
 	if (rq.errors == IDETAPE_ERROR_GENERAL)
 		return -EIO;
 	return (tape->blk_size * (blocks-rq.current_nr_sectors));
@@ -1777,7 +1766,7 @@ static int idetape_add_chrdev_write_request(ide_drive_t *drive, int blocks)
 	debug_log(DBG_CHRDEV, "Enter %s\n", __func__);
 
 	return idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE,
-				     blocks, tape->merge_stage->bh);
+				     blocks, tape->merge_bh);
 }
 
 static void ide_tape_flush_merge_buffer(ide_drive_t *drive)
@@ -1787,7 +1776,7 @@ static void ide_tape_flush_merge_buffer(ide_drive_t *drive)
 	struct idetape_bh *bh;
 
 	if (tape->chrdev_dir != IDETAPE_DIR_WRITE) {
-		printk(KERN_ERR "ide-tape: bug: Trying to empty write pipeline,"
+		printk(KERN_ERR "ide-tape: bug: Trying to empty merge buffer"
 				" but we are not writing.\n");
 		return;
 	}
@@ -1827,9 +1816,9 @@ static void ide_tape_flush_merge_buffer(ide_drive_t *drive)
 		(void) idetape_add_chrdev_write_request(drive, blocks);
 		tape->merge_bh_size = 0;
 	}
-	if (tape->merge_stage != NULL) {
-		ide_tape_kfree_buffer(tape->merge_stage);
-		tape->merge_stage = NULL;
+	if (tape->merge_bh != NULL) {
+		ide_tape_kfree_buffer(tape);
+		tape->merge_bh = NULL;
 	}
 	tape->chrdev_dir = IDETAPE_DIR_NONE;
 }
@@ -1845,13 +1834,13 @@ static int idetape_init_read(ide_drive_t *drive)
 			ide_tape_flush_merge_buffer(drive);
 			idetape_flush_tape_buffers(drive);
 		}
-		if (tape->merge_stage || tape->merge_bh_size) {
+		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_stage = ide_tape_kmalloc_buffer(tape, 0, 0);
-		if (!tape->merge_stage)
+		tape->merge_bh = ide_tape_kmalloc_buffer(tape, 0, 0);
+		if (!tape->merge_bh)
 			return -ENOMEM;
 		tape->chrdev_dir = IDETAPE_DIR_READ;
 
@@ -1864,10 +1853,10 @@ static int idetape_init_read(ide_drive_t *drive)
 		if (drive->dsc_overlap) {
 			bytes_read = idetape_queue_rw_tail(drive,
 							REQ_IDETAPE_READ, 0,
-							tape->merge_stage->bh);
+							tape->merge_bh);
 			if (bytes_read < 0) {
-				ide_tape_kfree_buffer(tape->merge_stage);
-				tape->merge_stage = NULL;
+				ide_tape_kfree_buffer(tape);
+				tape->merge_bh = NULL;
 				tape->chrdev_dir = IDETAPE_DIR_NONE;
 				return bytes_read;
 			}
@@ -1891,7 +1880,7 @@ 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_stage->bh);
+				     tape->merge_bh);
 }
 
 static void idetape_pad_zeros(ide_drive_t *drive, int bcount)
@@ -1903,7 +1892,7 @@ static void idetape_pad_zeros(ide_drive_t *drive, int bcount)
 	while (bcount) {
 		unsigned int count;
 
-		bh = tape->merge_stage->bh;
+		bh = tape->merge_bh;
 		count = min(tape->buffer_size, bcount);
 		bcount -= count;
 		blocks = count / tape->blk_size;
@@ -1915,7 +1904,7 @@ static void idetape_pad_zeros(ide_drive_t *drive, int bcount)
 			bh = bh->b_reqnext;
 		}
 		idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, blocks,
-				      tape->merge_stage->bh);
+				      tape->merge_bh);
 	}
 }
 
@@ -2000,10 +1989,6 @@ static int idetape_space_over_filemarks(ide_drive_t *drive, short mt_op,
 		ide_tape_discard_merge_buffer(drive, 0);
 	}
 
-	/*
-	 * The filemark was not found in our internal pipeline;	now we can issue
-	 * the space command.
-	 */
 	switch (mt_op) {
 	case MTFSF:
 	case MTBSF:
@@ -2123,16 +2108,16 @@ 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_stage || tape->merge_bh_size) {
+		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_stage = ide_tape_kmalloc_buffer(tape, 0, 0);
-		if (!tape->merge_stage)
+		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_stage(tape);
+		idetape_init_merge_buffer(tape);
 
 		/*
 		 * Issue a write 0 command to ensure that DSC handshake is
@@ -2143,10 +2128,10 @@ static ssize_t idetape_chrdev_write(struct file *file, const char __user *buf,
 		if (drive->dsc_overlap) {
 			ssize_t retval = idetape_queue_rw_tail(drive,
 							REQ_IDETAPE_WRITE, 0,
-							tape->merge_stage->bh);
+							tape->merge_bh);
 			if (retval < 0) {
-				ide_tape_kfree_buffer(tape->merge_stage);
-				tape->merge_stage = NULL;
+				ide_tape_kfree_buffer(tape);
+				tape->merge_bh = NULL;
 				tape->chrdev_dir = IDETAPE_DIR_NONE;
 				return retval;
 			}
@@ -2508,12 +2493,12 @@ 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_stage = ide_tape_kmalloc_buffer(tape, 1, 0);
-	if (tape->merge_stage != NULL) {
+	tape->merge_bh = ide_tape_kmalloc_buffer(tape, 1, 0);
+	if (tape->merge_bh != NULL) {
 		idetape_pad_zeros(drive, tape->blk_size *
 				(tape->user_bs_factor - 1));
-		ide_tape_kfree_buffer(tape->merge_stage);
-		tape->merge_stage = NULL;
+		ide_tape_kfree_buffer(tape);
+		tape->merge_bh = NULL;
 	}
 	idetape_write_filemark(drive);
 	idetape_flush_tape_buffers(drive);
-- 
1.5.4.1

[PATCH 6/6] ide-tape: fix mem leak

[Borislav Petkov]

On failed struct idetape_bh allocation the logic frees only one buffer page
which was the old page-wise strategy. Doing that now would probably leak
2^order-1 pages so fix it to free all and not only the first buffer page.

Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
---
 drivers/ide/ide-tape.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index 78a76a0..29870c4 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -1348,7 +1348,7 @@ static struct idetape_bh *ide_tape_kmalloc_buffer(idetape_tape_t *tape,
 		prev_bh = bh;
 		bh = kmalloc(sizeof(struct idetape_bh), GFP_KERNEL);
 		if (!bh) {
-			free_page((unsigned long) b_data);
+			free_pages((unsigned long) b_data, order);
 			goto abort;
 		}
 		bh->b_reqnext = NULL;
-- 
1.5.4.1

Re: [PATCH 0/6] ide-tape: refit tape data buffer bits/kill pipelining-v2

[Bartlomiej Zolnierkiewicz]

Hi,

On Monday 07 April 2008, Borislav Petkov wrote:
> Hi Bart,
> 
> here's another patchset that contains some other fixes along with the changes
> you suggested. We have now a tape->merge_bh buffer which is a singly linked list
> of bh's and tape->bh is a pointer within that list. The remaining pipelining
> functions have been readjusted to handle the merge buffer. I guess, that was it,
> pipelining is gone.
> 
>  drivers/ide/ide-tape.c |  215 ++++++++++++++++++++++--------------------------
>  1 files changed, 99 insertions(+), 116 deletions(-)

I applied all 6 patches, thanks!

Bart