diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index e516816f66a6..3ce43920e459 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -49,7 +49,11 @@
 
 #include "libata.h"
 
-#define SECTOR_SIZE	512
+#define SECTOR_SIZE		512
+#define ATA_SCSI_RBUF_SIZE	4096
+
+static DEFINE_SPINLOCK(ata_scsi_rbuf_lock);
+static u8 ata_scsi_rbuf[ATA_SCSI_RBUF_SIZE];
 
 typedef unsigned int (*ata_xlat_func_t)(struct ata_queued_cmd *qc);
 
@@ -1639,53 +1643,48 @@ static int ata_scsi_translate(struct ata_device *dev, struct scsi_cmnd *cmd,
 
 /**
  *	ata_scsi_rbuf_get - Map response buffer.
- *	@cmd: SCSI command containing buffer to be mapped.
- *	@buf_out: Pointer to mapped area.
+ *	@flags: unsigned long variable to store irq enable status
+ *	@copy_in: copy in from user buffer
  *
- *	Maps buffer contained within SCSI command @cmd.
+ *	Prepare buffer for simulated SCSI commands.
  *
  *	LOCKING:
- *	spin_lock_irqsave(host lock)
+ *	spin_lock_irqsave(ata_scsi_rbuf_lock) on success
  *
  *	RETURNS:
- *	Length of response buffer.
+ *	Pointer to response buffer.
  */
-
-static unsigned int ata_scsi_rbuf_get(struct scsi_cmnd *cmd, u8 **buf_out)
+static void *ata_scsi_rbuf_get(struct scsi_cmnd *cmd, bool copy_in,
+			       unsigned long *flags)
 {
-	u8 *buf;
-	unsigned int buflen;
+	spin_lock_irqsave(&ata_scsi_rbuf_lock, *flags);
 
-	struct scatterlist *sg = scsi_sglist(cmd);
-
-	if (sg) {
-		buf = kmap_atomic(sg_page(sg), KM_IRQ0) + sg->offset;
-		buflen = sg->length;
-	} else {
-		buf = NULL;
-		buflen = 0;
-	}
-
-	*buf_out = buf;
-	return buflen;
+	memset(ata_scsi_rbuf, 0, ATA_SCSI_RBUF_SIZE);
+	if (copy_in)
+		sg_copy_to_buffer(scsi_sglist(cmd), scsi_sg_count(cmd),
+				  ata_scsi_rbuf, ATA_SCSI_RBUF_SIZE);
+	return ata_scsi_rbuf;
 }
 
 /**
  *	ata_scsi_rbuf_put - Unmap response buffer.
  *	@cmd: SCSI command containing buffer to be unmapped.
- *	@buf: buffer to unmap
+ *	@copy_out: copy out result
+ *	@flags: @flags passed to ata_scsi_rbuf_get()
  *
- *	Unmaps response buffer contained within @cmd.
+ *	Returns rbuf buffer.  The result is copied to @cmd's buffer if
+ *	@copy_back is true.
  *
  *	LOCKING:
- *	spin_lock_irqsave(host lock)
+ *	Unlocks ata_scsi_rbuf_lock.
  */
-
-static inline void ata_scsi_rbuf_put(struct scsi_cmnd *cmd, u8 *buf)
+static inline void ata_scsi_rbuf_put(struct scsi_cmnd *cmd, bool copy_out,
+				     unsigned long *flags)
 {
-	struct scatterlist *sg = scsi_sglist(cmd);
-	if (sg)
-		kunmap_atomic(buf - sg->offset, KM_IRQ0);
+	if (copy_out)
+		sg_copy_from_buffer(scsi_sglist(cmd), scsi_sg_count(cmd),
+				    ata_scsi_rbuf, ATA_SCSI_RBUF_SIZE);
+	spin_unlock_irqrestore(&ata_scsi_rbuf_lock, *flags);
 }
 
 /**
@@ -1704,49 +1703,26 @@ static inline void ata_scsi_rbuf_put(struct scsi_cmnd *cmd, u8 *buf)
  *	spin_lock_irqsave(host lock)
  */
 static void ata_scsi_rbuf_fill(struct ata_scsi_args *args,
-			unsigned int (*actor)(struct ata_scsi_args *args,
-					      u8 *rbuf, unsigned int buflen))
+		unsigned int (*actor)(struct ata_scsi_args *args, u8 *rbuf))
 {
 	u8 *rbuf;
-	unsigned int buflen, rc;
+	unsigned int rc;
 	struct scsi_cmnd *cmd = args->cmd;
 	unsigned long flags;
 
-	local_irq_save(flags);
-
-	buflen = ata_scsi_rbuf_get(cmd, &rbuf);
-	memset(rbuf, 0, buflen);
-	rc = actor(args, rbuf, buflen);
-	ata_scsi_rbuf_put(cmd, rbuf);
-
-	local_irq_restore(flags);
+	rbuf = ata_scsi_rbuf_get(cmd, false, &flags);
+	rc = actor(args, rbuf);
+	ata_scsi_rbuf_put(cmd, rc == 0, &flags);
 
 	if (rc == 0)
 		cmd->result = SAM_STAT_GOOD;
 	args->done(cmd);
 }
 
-/**
- *	ATA_SCSI_RBUF_SET - helper to set values in SCSI response buffer
- *	@idx: byte index into SCSI response buffer
- *	@val: value to set
- *
- *	To be used by SCSI command simulator functions.  This macros
- *	expects two local variables, u8 *rbuf and unsigned int buflen,
- *	are in scope.
- *
- *	LOCKING:
- *	None.
- */
-#define ATA_SCSI_RBUF_SET(idx, val) do { \
-		if ((idx) < buflen) rbuf[(idx)] = (u8)(val); \
-	} while (0)
-
 /**
  *	ata_scsiop_inq_std - Simulate INQUIRY command
  *	@args: device IDENTIFY data / SCSI command of interest.
  *	@rbuf: Response buffer, to which simulated SCSI cmd output is sent.
- *	@buflen: Response buffer length.
  *
  *	Returns standard device identification data associated
  *	with non-VPD INQUIRY command output.
@@ -1754,9 +1730,17 @@ static void ata_scsi_rbuf_fill(struct ata_scsi_args *args,
  *	LOCKING:
  *	spin_lock_irqsave(host lock)
  */
-static unsigned int ata_scsiop_inq_std(struct ata_scsi_args *args, u8 *rbuf,
-				       unsigned int buflen)
+static unsigned int ata_scsiop_inq_std(struct ata_scsi_args *args, u8 *rbuf)
 {
+	const u8 versions[] = {
+		0x60,	/* SAM-3 (no version claimed) */
+
+		0x03,
+		0x20,	/* SBC-2 (no version claimed) */
+
+		0x02,
+		0x60	/* SPC-3 (no version claimed) */
+	};
 	u8 hdr[] = {
 		TYPE_DISK,
 		0,
@@ -1765,35 +1749,21 @@ static unsigned int ata_scsiop_inq_std(struct ata_scsi_args *args, u8 *rbuf,
 		95 - 4
 	};
 
+	VPRINTK("ENTER\n");
+
 	/* set scsi removeable (RMB) bit per ata bit */
 	if (ata_id_removeable(args->id))
 		hdr[1] |= (1 << 7);
 
-	VPRINTK("ENTER\n");
-
 	memcpy(rbuf, hdr, sizeof(hdr));
+	memcpy(&rbuf[8], "ATA     ", 8);
+	ata_id_string(args->id, &rbuf[16], ATA_ID_PROD, 16);
+	ata_id_string(args->id, &rbuf[32], ATA_ID_FW_REV, 4);
 
-	if (buflen > 35) {
-		memcpy(&rbuf[8], "ATA     ", 8);
-		ata_id_string(args->id, &rbuf[16], ATA_ID_PROD, 16);
-		ata_id_string(args->id, &rbuf[32], ATA_ID_FW_REV, 4);
-		if (rbuf[32] == 0 || rbuf[32] == ' ')
-			memcpy(&rbuf[32], "n/a ", 4);
-	}
+	if (rbuf[32] == 0 || rbuf[32] == ' ')
+		memcpy(&rbuf[32], "n/a ", 4);
 
-	if (buflen > 63) {
-		const u8 versions[] = {
-			0x60,	/* SAM-3 (no version claimed) */
-
-			0x03,
-			0x20,	/* SBC-2 (no version claimed) */
-
-			0x02,
-			0x60	/* SPC-3 (no version claimed) */
-		};
-
-		memcpy(rbuf + 59, versions, sizeof(versions));
-	}
+	memcpy(rbuf + 59, versions, sizeof(versions));
 
 	return 0;
 }
@@ -1802,26 +1772,22 @@ static unsigned int ata_scsiop_inq_std(struct ata_scsi_args *args, u8 *rbuf,
  *	ata_scsiop_inq_00 - Simulate INQUIRY VPD page 0, list of pages
  *	@args: device IDENTIFY data / SCSI command of interest.
  *	@rbuf: Response buffer, to which simulated SCSI cmd output is sent.
- *	@buflen: Response buffer length.
  *
  *	Returns list of inquiry VPD pages available.
  *
  *	LOCKING:
  *	spin_lock_irqsave(host lock)
  */
-static unsigned int ata_scsiop_inq_00(struct ata_scsi_args *args, u8 *rbuf,
-				      unsigned int buflen)
+static unsigned int ata_scsiop_inq_00(struct ata_scsi_args *args, u8 *rbuf)
 {
 	const u8 pages[] = {
 		0x00,	/* page 0x00, this page */
 		0x80,	/* page 0x80, unit serial no page */
 		0x83	/* page 0x83, device ident page */
 	};
+
 	rbuf[3] = sizeof(pages);	/* number of supported VPD pages */
-
-	if (buflen > 6)
-		memcpy(rbuf + 4, pages, sizeof(pages));
-
+	memcpy(rbuf + 4, pages, sizeof(pages));
 	return 0;
 }
 
@@ -1829,15 +1795,13 @@ static unsigned int ata_scsiop_inq_00(struct ata_scsi_args *args, u8 *rbuf,
  *	ata_scsiop_inq_80 - Simulate INQUIRY VPD page 80, device serial number
  *	@args: device IDENTIFY data / SCSI command of interest.
  *	@rbuf: Response buffer, to which simulated SCSI cmd output is sent.
- *	@buflen: Response buffer length.
  *
  *	Returns ATA device serial number.
  *
  *	LOCKING:
  *	spin_lock_irqsave(host lock)
  */
-static unsigned int ata_scsiop_inq_80(struct ata_scsi_args *args, u8 *rbuf,
-				      unsigned int buflen)
+static unsigned int ata_scsiop_inq_80(struct ata_scsi_args *args, u8 *rbuf)
 {
 	const u8 hdr[] = {
 		0,
@@ -1845,12 +1809,10 @@ static unsigned int ata_scsiop_inq_80(struct ata_scsi_args *args, u8 *rbuf,
 		0,
 		ATA_ID_SERNO_LEN,	/* page len */
 	};
+
 	memcpy(rbuf, hdr, sizeof(hdr));
-
-	if (buflen > (ATA_ID_SERNO_LEN + 4 - 1))
-		ata_id_string(args->id, (unsigned char *) &rbuf[4],
-			      ATA_ID_SERNO, ATA_ID_SERNO_LEN);
-
+	ata_id_string(args->id, (unsigned char *) &rbuf[4],
+		      ATA_ID_SERNO, ATA_ID_SERNO_LEN);
 	return 0;
 }
 
@@ -1858,7 +1820,6 @@ static unsigned int ata_scsiop_inq_80(struct ata_scsi_args *args, u8 *rbuf,
  *	ata_scsiop_inq_83 - Simulate INQUIRY VPD page 83, device identity
  *	@args: device IDENTIFY data / SCSI command of interest.
  *	@rbuf: Response buffer, to which simulated SCSI cmd output is sent.
- *	@buflen: Response buffer length.
  *
  *	Yields two logical unit device identification designators:
  *	 - vendor specific ASCII containing the ATA serial number
@@ -1868,40 +1829,37 @@ static unsigned int ata_scsiop_inq_80(struct ata_scsi_args *args, u8 *rbuf,
  *	LOCKING:
  *	spin_lock_irqsave(host lock)
  */
-static unsigned int ata_scsiop_inq_83(struct ata_scsi_args *args, u8 *rbuf,
-				      unsigned int buflen)
+static unsigned int ata_scsiop_inq_83(struct ata_scsi_args *args, u8 *rbuf)
 {
-	int num;
 	const int sat_model_serial_desc_len = 68;
+	int num;
 
 	rbuf[1] = 0x83;			/* this page code */
 	num = 4;
 
-	if (buflen > (ATA_ID_SERNO_LEN + num + 3)) {
-		/* piv=0, assoc=lu, code_set=ACSII, designator=vendor */
-		rbuf[num + 0] = 2;
-		rbuf[num + 3] = ATA_ID_SERNO_LEN;
-		num += 4;
-		ata_id_string(args->id, (unsigned char *) rbuf + num,
-			      ATA_ID_SERNO, ATA_ID_SERNO_LEN);
-		num += ATA_ID_SERNO_LEN;
-	}
-	if (buflen > (sat_model_serial_desc_len + num + 3)) {
-		/* SAT defined lu model and serial numbers descriptor */
-		/* piv=0, assoc=lu, code_set=ACSII, designator=t10 vendor id */
-		rbuf[num + 0] = 2;
-		rbuf[num + 1] = 1;
-		rbuf[num + 3] = sat_model_serial_desc_len;
-		num += 4;
-		memcpy(rbuf + num, "ATA     ", 8);
-		num += 8;
-		ata_id_string(args->id, (unsigned char *) rbuf + num,
-			      ATA_ID_PROD, ATA_ID_PROD_LEN);
-		num += ATA_ID_PROD_LEN;
-		ata_id_string(args->id, (unsigned char *) rbuf + num,
-			      ATA_ID_SERNO, ATA_ID_SERNO_LEN);
-		num += ATA_ID_SERNO_LEN;
-	}
+	/* piv=0, assoc=lu, code_set=ACSII, designator=vendor */
+	rbuf[num + 0] = 2;
+	rbuf[num + 3] = ATA_ID_SERNO_LEN;
+	num += 4;
+	ata_id_string(args->id, (unsigned char *) rbuf + num,
+		      ATA_ID_SERNO, ATA_ID_SERNO_LEN);
+	num += ATA_ID_SERNO_LEN;
+
+	/* SAT defined lu model and serial numbers descriptor */
+	/* piv=0, assoc=lu, code_set=ACSII, designator=t10 vendor id */
+	rbuf[num + 0] = 2;
+	rbuf[num + 1] = 1;
+	rbuf[num + 3] = sat_model_serial_desc_len;
+	num += 4;
+	memcpy(rbuf + num, "ATA     ", 8);
+	num += 8;
+	ata_id_string(args->id, (unsigned char *) rbuf + num, ATA_ID_PROD,
+		      ATA_ID_PROD_LEN);
+	num += ATA_ID_PROD_LEN;
+	ata_id_string(args->id, (unsigned char *) rbuf + num, ATA_ID_SERNO,
+		      ATA_ID_SERNO_LEN);
+	num += ATA_ID_SERNO_LEN;
+
 	rbuf[3] = num - 4;    /* page len (assume less than 256 bytes) */
 	return 0;
 }
@@ -1910,34 +1868,26 @@ static unsigned int ata_scsiop_inq_83(struct ata_scsi_args *args, u8 *rbuf,
  *	ata_scsiop_inq_89 - Simulate INQUIRY VPD page 89, ATA info
  *	@args: device IDENTIFY data / SCSI command of interest.
  *	@rbuf: Response buffer, to which simulated SCSI cmd output is sent.
- *	@buflen: Response buffer length.
  *
  *	Yields SAT-specified ATA VPD page.
  *
  *	LOCKING:
  *	spin_lock_irqsave(host lock)
  */
-static unsigned int ata_scsiop_inq_89(struct ata_scsi_args *args, u8 *rbuf,
-				      unsigned int buflen)
+static unsigned int ata_scsiop_inq_89(struct ata_scsi_args *args, u8 *rbuf)
 {
-	u8 pbuf[60];
 	struct ata_taskfile tf;
-	unsigned int i;
 
-	if (!buflen)
-		return 0;
-
-	memset(&pbuf, 0, sizeof(pbuf));
 	memset(&tf, 0, sizeof(tf));
 
-	pbuf[1] = 0x89;			/* our page code */
-	pbuf[2] = (0x238 >> 8);		/* page size fixed at 238h */
-	pbuf[3] = (0x238 & 0xff);
+	rbuf[1] = 0x89;			/* our page code */
+	rbuf[2] = (0x238 >> 8);		/* page size fixed at 238h */
+	rbuf[3] = (0x238 & 0xff);
 
-	memcpy(&pbuf[8], "linux   ", 8);
-	memcpy(&pbuf[16], "libata          ", 16);
-	memcpy(&pbuf[32], DRV_VERSION, 4);
-	ata_id_string(args->id, &pbuf[32], ATA_ID_FW_REV, 4);
+	memcpy(&rbuf[8], "linux   ", 8);
+	memcpy(&rbuf[16], "libata          ", 16);
+	memcpy(&rbuf[32], DRV_VERSION, 4);
+	ata_id_string(args->id, &rbuf[32], ATA_ID_FW_REV, 4);
 
 	/* we don't store the ATA device signature, so we fake it */
 
@@ -1945,19 +1895,12 @@ static unsigned int ata_scsiop_inq_89(struct ata_scsi_args *args, u8 *rbuf,
 	tf.lbal = 0x1;
 	tf.nsect = 0x1;
 
-	ata_tf_to_fis(&tf, 0, 1, &pbuf[36]);	/* TODO: PMP? */
-	pbuf[36] = 0x34;		/* force D2H Reg FIS (34h) */
+	ata_tf_to_fis(&tf, 0, 1, &rbuf[36]);	/* TODO: PMP? */
+	rbuf[36] = 0x34;		/* force D2H Reg FIS (34h) */
 
-	pbuf[56] = ATA_CMD_ID_ATA;
+	rbuf[56] = ATA_CMD_ID_ATA;
 
-	i = min(buflen, 60U);
-	memcpy(rbuf, &pbuf[0], i);
-	buflen -= i;
-
-	if (!buflen)
-		return 0;
-
-	memcpy(&rbuf[60], &args->id[0], min(buflen, 512U));
+	memcpy(&rbuf[60], &args->id[0], 512);
 	return 0;
 }
 
@@ -1965,7 +1908,6 @@ static unsigned int ata_scsiop_inq_89(struct ata_scsi_args *args, u8 *rbuf,
  *	ata_scsiop_noop - Command handler that simply returns success.
  *	@args: device IDENTIFY data / SCSI command of interest.
  *	@rbuf: Response buffer, to which simulated SCSI cmd output is sent.
- *	@buflen: Response buffer length.
  *
  *	No operation.  Simply returns success to caller, to indicate
  *	that the caller should successfully complete this SCSI command.
@@ -1973,46 +1915,16 @@ static unsigned int ata_scsiop_inq_89(struct ata_scsi_args *args, u8 *rbuf,
  *	LOCKING:
  *	spin_lock_irqsave(host lock)
  */
-static unsigned int ata_scsiop_noop(struct ata_scsi_args *args, u8 *rbuf,
-				    unsigned int buflen)
+static unsigned int ata_scsiop_noop(struct ata_scsi_args *args, u8 *rbuf)
 {
 	VPRINTK("ENTER\n");
 	return 0;
 }
 
-/**
- *	ata_msense_push - Push data onto MODE SENSE data output buffer
- *	@ptr_io: (input/output) Location to store more output data
- *	@last: End of output data buffer
- *	@buf: Pointer to BLOB being added to output buffer
- *	@buflen: Length of BLOB
- *
- *	Store MODE SENSE data on an output buffer.
- *
- *	LOCKING:
- *	None.
- */
-
-static void ata_msense_push(u8 **ptr_io, const u8 *last,
-			    const u8 *buf, unsigned int buflen)
-{
-	u8 *ptr = *ptr_io;
-
-	if ((ptr + buflen - 1) > last)
-		return;
-
-	memcpy(ptr, buf, buflen);
-
-	ptr += buflen;
-
-	*ptr_io = ptr;
-}
-
 /**
  *	ata_msense_caching - Simulate MODE SENSE caching info page
  *	@id: device IDENTIFY data
- *	@ptr_io: (input/output) Location to store more output data
- *	@last: End of output data buffer
+ *	@buf: output buffer
  *
  *	Generate a caching info page, which conditionally indicates
  *	write caching to the SCSI layer, depending on device
@@ -2021,58 +1933,43 @@ static void ata_msense_push(u8 **ptr_io, const u8 *last,
  *	LOCKING:
  *	None.
  */
-
-static unsigned int ata_msense_caching(u16 *id, u8 **ptr_io,
-				       const u8 *last)
+static unsigned int ata_msense_caching(u16 *id, u8 *buf)
 {
-	u8 page[CACHE_MPAGE_LEN];
-
-	memcpy(page, def_cache_mpage, sizeof(page));
+	memcpy(buf, def_cache_mpage, sizeof(def_cache_mpage));
 	if (ata_id_wcache_enabled(id))
-		page[2] |= (1 << 2);	/* write cache enable */
+		buf[2] |= (1 << 2);	/* write cache enable */
 	if (!ata_id_rahead_enabled(id))
-		page[12] |= (1 << 5);	/* disable read ahead */
-
-	ata_msense_push(ptr_io, last, page, sizeof(page));
-	return sizeof(page);
+		buf[12] |= (1 << 5);	/* disable read ahead */
+	return sizeof(def_cache_mpage);
 }
 
 /**
  *	ata_msense_ctl_mode - Simulate MODE SENSE control mode page
- *	@dev: Device associated with this MODE SENSE command
- *	@ptr_io: (input/output) Location to store more output data
- *	@last: End of output data buffer
+ *	@buf: output buffer
  *
  *	Generate a generic MODE SENSE control mode page.
  *
  *	LOCKING:
  *	None.
  */
-
-static unsigned int ata_msense_ctl_mode(u8 **ptr_io, const u8 *last)
+static unsigned int ata_msense_ctl_mode(u8 *buf)
 {
-	ata_msense_push(ptr_io, last, def_control_mpage,
-			sizeof(def_control_mpage));
+	memcpy(buf, def_control_mpage, sizeof(def_control_mpage));
 	return sizeof(def_control_mpage);
 }
 
 /**
  *	ata_msense_rw_recovery - Simulate MODE SENSE r/w error recovery page
- *	@dev: Device associated with this MODE SENSE command
- *	@ptr_io: (input/output) Location to store more output data
- *	@last: End of output data buffer
+ *	@bufp: output buffer
  *
  *	Generate a generic MODE SENSE r/w error recovery page.
  *
  *	LOCKING:
  *	None.
  */
-
-static unsigned int ata_msense_rw_recovery(u8 **ptr_io, const u8 *last)
+static unsigned int ata_msense_rw_recovery(u8 *buf)
 {
-
-	ata_msense_push(ptr_io, last, def_rw_recovery_mpage,
-			sizeof(def_rw_recovery_mpage));
+	memcpy(buf, def_rw_recovery_mpage, sizeof(def_rw_recovery_mpage));
 	return sizeof(def_rw_recovery_mpage);
 }
 
@@ -2104,7 +2001,6 @@ static int ata_dev_supports_fua(u16 *id)
  *	ata_scsiop_mode_sense - Simulate MODE SENSE 6, 10 commands
  *	@args: device IDENTIFY data / SCSI command of interest.
  *	@rbuf: Response buffer, to which simulated SCSI cmd output is sent.
- *	@buflen: Response buffer length.
  *
  *	Simulate MODE SENSE commands. Assume this is invoked for direct
  *	access devices (e.g. disks) only. There should be no block
@@ -2113,19 +2009,17 @@ static int ata_dev_supports_fua(u16 *id)
  *	LOCKING:
  *	spin_lock_irqsave(host lock)
  */
-
-unsigned int ata_scsiop_mode_sense(struct ata_scsi_args *args, u8 *rbuf,
-				  unsigned int buflen)
+static unsigned int ata_scsiop_mode_sense(struct ata_scsi_args *args, u8 *rbuf)
 {
 	struct ata_device *dev = args->dev;
-	u8 *scsicmd = args->cmd->cmnd, *p, *last;
+	u8 *scsicmd = args->cmd->cmnd, *p = rbuf;
 	const u8 sat_blk_desc[] = {
 		0, 0, 0, 0,	/* number of blocks: sat unspecified */
 		0,
 		0, 0x2, 0x0	/* block length: 512 bytes */
 	};
 	u8 pg, spg;
-	unsigned int ebd, page_control, six_byte, output_len, alloc_len, minlen;
+	unsigned int ebd, page_control, six_byte;
 	u8 dpofua;
 
 	VPRINTK("ENTER\n");
@@ -2148,17 +2042,10 @@ unsigned int ata_scsiop_mode_sense(struct ata_scsi_args *args, u8 *rbuf,
 		goto invalid_fld;
 	}
 
-	if (six_byte) {
-		output_len = 4 + (ebd ? 8 : 0);
-		alloc_len = scsicmd[4];
-	} else {
-		output_len = 8 + (ebd ? 8 : 0);
-		alloc_len = (scsicmd[7] << 8) + scsicmd[8];
-	}
-	minlen = (alloc_len < buflen) ? alloc_len : buflen;
-
-	p = rbuf + output_len;
-	last = rbuf + minlen - 1;
+	if (six_byte)
+		p += 4 + (ebd ? 8 : 0);
+	else
+		p += 8 + (ebd ? 8 : 0);
 
 	pg = scsicmd[2] & 0x3f;
 	spg = scsicmd[3];
@@ -2171,61 +2058,48 @@ unsigned int ata_scsiop_mode_sense(struct ata_scsi_args *args, u8 *rbuf,
 
 	switch(pg) {
 	case RW_RECOVERY_MPAGE:
-		output_len += ata_msense_rw_recovery(&p, last);
+		p += ata_msense_rw_recovery(p);
 		break;
 
 	case CACHE_MPAGE:
-		output_len += ata_msense_caching(args->id, &p, last);
+		p += ata_msense_caching(args->id, p);
 		break;
 
-	case CONTROL_MPAGE: {
-		output_len += ata_msense_ctl_mode(&p, last);
+	case CONTROL_MPAGE:
+		p += ata_msense_ctl_mode(p);
 		break;
-		}
 
 	case ALL_MPAGES:
-		output_len += ata_msense_rw_recovery(&p, last);
-		output_len += ata_msense_caching(args->id, &p, last);
-		output_len += ata_msense_ctl_mode(&p, last);
+		p += ata_msense_rw_recovery(p);
+		p += ata_msense_caching(args->id, p);
+		p += ata_msense_ctl_mode(p);
 		break;
 
 	default:		/* invalid page code */
 		goto invalid_fld;
 	}
 
-	if (minlen < 1)
-		return 0;
-
 	dpofua = 0;
 	if (ata_dev_supports_fua(args->id) && (dev->flags & ATA_DFLAG_LBA48) &&
 	    (!(dev->flags & ATA_DFLAG_PIO) || dev->multi_count))
 		dpofua = 1 << 4;
 
 	if (six_byte) {
-		output_len--;
-		rbuf[0] = output_len;
-		if (minlen > 2)
-			rbuf[2] |= dpofua;
+		rbuf[0] = p - rbuf - 1;
+		rbuf[2] |= dpofua;
 		if (ebd) {
-			if (minlen > 3)
-				rbuf[3] = sizeof(sat_blk_desc);
-			if (minlen > 11)
-				memcpy(rbuf + 4, sat_blk_desc,
-				       sizeof(sat_blk_desc));
+			rbuf[3] = sizeof(sat_blk_desc);
+			memcpy(rbuf + 4, sat_blk_desc, sizeof(sat_blk_desc));
 		}
 	} else {
-		output_len -= 2;
+		unsigned int output_len = p - rbuf - 2;
+
 		rbuf[0] = output_len >> 8;
-		if (minlen > 1)
-			rbuf[1] = output_len;
-		if (minlen > 3)
-			rbuf[3] |= dpofua;
+		rbuf[1] = output_len;
+		rbuf[3] |= dpofua;
 		if (ebd) {
-			if (minlen > 7)
-				rbuf[7] = sizeof(sat_blk_desc);
-			if (minlen > 15)
-				memcpy(rbuf + 8, sat_blk_desc,
-				       sizeof(sat_blk_desc));
+			rbuf[7] = sizeof(sat_blk_desc);
+			memcpy(rbuf + 8, sat_blk_desc, sizeof(sat_blk_desc));
 		}
 	}
 	return 0;
@@ -2245,15 +2119,13 @@ unsigned int ata_scsiop_mode_sense(struct ata_scsi_args *args, u8 *rbuf,
  *	ata_scsiop_read_cap - Simulate READ CAPACITY[ 16] commands
  *	@args: device IDENTIFY data / SCSI command of interest.
  *	@rbuf: Response buffer, to which simulated SCSI cmd output is sent.
- *	@buflen: Response buffer length.
  *
  *	Simulate READ CAPACITY commands.
  *
  *	LOCKING:
  *	None.
  */
-unsigned int ata_scsiop_read_cap(struct ata_scsi_args *args, u8 *rbuf,
-				 unsigned int buflen)
+static unsigned int ata_scsiop_read_cap(struct ata_scsi_args *args, u8 *rbuf)
 {
 	u64 last_lba = args->dev->n_sectors - 1; /* LBA of the last block */
 
@@ -2264,28 +2136,28 @@ unsigned int ata_scsiop_read_cap(struct ata_scsi_args *args, u8 *rbuf,
 			last_lba = 0xffffffff;
 
 		/* sector count, 32-bit */
-		ATA_SCSI_RBUF_SET(0, last_lba >> (8 * 3));
-		ATA_SCSI_RBUF_SET(1, last_lba >> (8 * 2));
-		ATA_SCSI_RBUF_SET(2, last_lba >> (8 * 1));
-		ATA_SCSI_RBUF_SET(3, last_lba);
+		rbuf[0] = last_lba >> (8 * 3);
+		rbuf[1] = last_lba >> (8 * 2);
+		rbuf[2] = last_lba >> (8 * 1);
+		rbuf[3] = last_lba;
 
 		/* sector size */
-		ATA_SCSI_RBUF_SET(6, ATA_SECT_SIZE >> 8);
-		ATA_SCSI_RBUF_SET(7, ATA_SECT_SIZE & 0xff);
+		rbuf[6] = ATA_SECT_SIZE >> 8;
+		rbuf[7] = ATA_SECT_SIZE & 0xff;
 	} else {
 		/* sector count, 64-bit */
-		ATA_SCSI_RBUF_SET(0, last_lba >> (8 * 7));
-		ATA_SCSI_RBUF_SET(1, last_lba >> (8 * 6));
-		ATA_SCSI_RBUF_SET(2, last_lba >> (8 * 5));
-		ATA_SCSI_RBUF_SET(3, last_lba >> (8 * 4));
-		ATA_SCSI_RBUF_SET(4, last_lba >> (8 * 3));
-		ATA_SCSI_RBUF_SET(5, last_lba >> (8 * 2));
-		ATA_SCSI_RBUF_SET(6, last_lba >> (8 * 1));
-		ATA_SCSI_RBUF_SET(7, last_lba);
+		rbuf[0] = last_lba >> (8 * 7);
+		rbuf[1] = last_lba >> (8 * 6);
+		rbuf[2] = last_lba >> (8 * 5);
+		rbuf[3] = last_lba >> (8 * 4);
+		rbuf[4] = last_lba >> (8 * 3);
+		rbuf[5] = last_lba >> (8 * 2);
+		rbuf[6] = last_lba >> (8 * 1);
+		rbuf[7] = last_lba;
 
 		/* sector size */
-		ATA_SCSI_RBUF_SET(10, ATA_SECT_SIZE >> 8);
-		ATA_SCSI_RBUF_SET(11, ATA_SECT_SIZE & 0xff);
+		rbuf[10] = ATA_SECT_SIZE >> 8;
+		rbuf[11] = ATA_SECT_SIZE & 0xff;
 	}
 
 	return 0;
@@ -2295,16 +2167,13 @@ unsigned int ata_scsiop_read_cap(struct ata_scsi_args *args, u8 *rbuf,
  *	ata_scsiop_report_luns - Simulate REPORT LUNS command
  *	@args: device IDENTIFY data / SCSI command of interest.
  *	@rbuf: Response buffer, to which simulated SCSI cmd output is sent.
- *	@buflen: Response buffer length.
  *
  *	Simulate REPORT LUNS command.
  *
  *	LOCKING:
  *	spin_lock_irqsave(host lock)
  */
-
-unsigned int ata_scsiop_report_luns(struct ata_scsi_args *args, u8 *rbuf,
-				   unsigned int buflen)
+static unsigned int ata_scsiop_report_luns(struct ata_scsi_args *args, u8 *rbuf)
 {
 	VPRINTK("ENTER\n");
 	rbuf[3] = 8;	/* just one lun, LUN 0, size 8 bytes */
@@ -2438,13 +2307,10 @@ static void atapi_qc_complete(struct ata_queued_cmd *qc)
 		u8 *scsicmd = cmd->cmnd;
 
 		if ((scsicmd[0] == INQUIRY) && ((scsicmd[1] & 0x03) == 0)) {
-			u8 *buf = NULL;
-			unsigned int buflen;
 			unsigned long flags;
+			u8 *buf;
 
-			local_irq_save(flags);
-
-			buflen = ata_scsi_rbuf_get(cmd, &buf);
+			buf = ata_scsi_rbuf_get(cmd, true, &flags);
 
 	/* ATAPI devices typically report zero for their SCSI version,
 	 * and sometimes deviate from the spec WRT response data
@@ -2459,9 +2325,7 @@ static void atapi_qc_complete(struct ata_queued_cmd *qc)
 				buf[3] = 0x32;
 			}
 
-			ata_scsi_rbuf_put(cmd, buf);
-
-			local_irq_restore(flags);
+			ata_scsi_rbuf_put(cmd, true, &flags);
 		}
 
 		cmd->result = SAM_STAT_GOOD;