[libata] scsi: implement MODE SELECT command

The cache_type file in sysfs lets users configure the disk cache in write-through or write-back modes. However, ata disks do not support writing to the file because they do not implement the MODE SELECT command. This patch adds a translation from MODE SELECT (for the caching page only) to the ATA SET FEATURES command. The set of changeable parameters answered by MODE SENSE is also adjusted accordingly. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

[libata] scsi: implement MODE SELECT command
The cache_type file in sysfs lets users configure the disk cache in write-through or write-back modes. However, ata disks do not support writing to the file because they do not implement the MODE SELECT command. This patch adds a translation from MODE SELECT (for the caching page only) to the ATA SET FEATURES command. The set of changeable parameters answered by MODE SENSE is also adjusted accordingly. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Paolo Bonzini · Jeff Garzik
1 parent 6ca8e79466
Showing 1 changed file with 188 additions and 6 deletions Side-by-side Diff
drivers/ata/libata-scsi.c
@@ -2243,7 +2243,7 @@
 static unsigned int ata_msense_caching(u16 *id, u8 *buf, bool changeable)
 {
 	modecpy(buf, def_cache_mpage, sizeof(def_cache_mpage), changeable);
-	if (!changeable && ata_id_wcache_enabled(id))
+	if (changeable || ata_id_wcache_enabled(id))
 		buf[2] |= (1 << 2);	/* write cache enable */
 	if (!changeable && !ata_id_rahead_enabled(id))
 		buf[12] |= (1 << 5);	/* disable read ahead */
@@ -3107,6 +3107,188 @@
 }
  
 /**
+ *	ata_mselect_caching - Simulate MODE SELECT for caching info page
+ *	@qc: Storage for translated ATA taskfile
+ *	@buf: input buffer
+ *	@len: number of valid bytes in the input buffer
+ *
+ *	Prepare a taskfile to modify caching information for the device.
+ *
+ *	LOCKING:
+ *	None.
+ */
+static int ata_mselect_caching(struct ata_queued_cmd *qc,
+			       const u8 *buf, int len)
+{
+	struct ata_taskfile *tf = &qc->tf;
+	struct ata_device *dev = qc->dev;
+	char mpage[CACHE_MPAGE_LEN];
+	u8 wce;
+
+	/*
+	 * The first two bytes of def_cache_mpage are a header, so offsets
+	 * in mpage are off by 2 compared to buf.  Same for len.
+	 */
+
+	if (len != CACHE_MPAGE_LEN - 2)
+		return -EINVAL;
+
+	wce = buf[0] & (1 << 2);
+
+	/*
+	 * Check that read-only bits are not modified.
+	 */
+	ata_msense_caching(dev->id, mpage, false);
+	mpage[2] &= ~(1 << 2);
+	mpage[2] |= wce;
+	if (memcmp(mpage + 2, buf, CACHE_MPAGE_LEN - 2) != 0)
+		return -EINVAL;
+
+	tf->flags |= ATA_TFLAG_DEVICE | ATA_TFLAG_ISADDR;
+	tf->protocol = ATA_PROT_NODATA;
+	tf->nsect = 0;
+	tf->command = ATA_CMD_SET_FEATURES;
+	tf->feature = wce ? SETFEATURES_WC_ON : SETFEATURES_WC_OFF;
+	return 0;
+}
+
+/**
+ *	ata_scsiop_mode_select - Simulate MODE SELECT 6, 10 commands
+ *	@qc: Storage for translated ATA taskfile
+ *
+ *	Converts a MODE SELECT command to an ATA SET FEATURES taskfile.
+ *	Assume this is invoked for direct access devices (e.g. disks) only.
+ *	There should be no block descriptor for other device types.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host lock)
+ */
+static unsigned int ata_scsi_mode_select_xlat(struct ata_queued_cmd *qc)
+{
+	struct scsi_cmnd *scmd = qc->scsicmd;
+	const u8 *cdb = scmd->cmnd;
+	const u8 *p;
+	u8 pg, spg;
+	unsigned six_byte, pg_len, hdr_len, bd_len;
+	int len;
+
+	VPRINTK("ENTER\n");
+
+	six_byte = (cdb[0] == MODE_SELECT);
+	if (six_byte) {
+		if (scmd->cmd_len < 5)
+			goto invalid_fld;
+
+		len = cdb[4];
+		hdr_len = 4;
+	} else {
+		if (scmd->cmd_len < 9)
+			goto invalid_fld;
+
+		len = (cdb[7] << 8) + cdb[8];
+		hdr_len = 8;
+	}
+
+	/* We only support PF=1, SP=0.  */
+	if ((cdb[1] & 0x11) != 0x10)
+		goto invalid_fld;
+
+	/* Test early for possible overrun.  */
+	if (!scsi_sg_count(scmd) || scsi_sglist(scmd)->length < len)
+		goto invalid_param_len;
+
+	p = page_address(sg_page(scsi_sglist(scmd)));
+
+	/* Move past header and block descriptors.  */
+	if (len < hdr_len)
+		goto invalid_param_len;
+
+	if (six_byte)
+		bd_len = p[3];
+	else
+		bd_len = (p[6] << 8) + p[7];
+
+	len -= hdr_len;
+	p += hdr_len;
+	if (len < bd_len)
+		goto invalid_param_len;
+	if (bd_len != 0 && bd_len != 8)
+		goto invalid_param;
+
+	len -= bd_len;
+	p += bd_len;
+	if (len == 0)
+		goto skip;
+
+	/* Parse both possible formats for the mode page headers.  */
+	pg = p[0] & 0x3f;
+	if (p[0] & 0x40) {
+		if (len < 4)
+			goto invalid_param_len;
+
+		spg = p[1];
+		pg_len = (p[2] << 8) | p[3];
+		p += 4;
+		len -= 4;
+	} else {
+		if (len < 2)
+			goto invalid_param_len;
+
+		spg = 0;
+		pg_len = p[1];
+		p += 2;
+		len -= 2;
+	}
+
+	/*
+	 * No mode subpages supported (yet) but asking for _all_
+	 * subpages may be valid
+	 */
+	if (spg && (spg != ALL_SUB_MPAGES))
+		goto invalid_param;
+	if (pg_len > len)
+		goto invalid_param_len;
+
+	switch (pg) {
+	case CACHE_MPAGE:
+		if (ata_mselect_caching(qc, p, pg_len) < 0)
+			goto invalid_param;
+		break;
+
+	default:		/* invalid page code */
+		goto invalid_param;
+	}
+
+	/*
+	 * Only one page has changeable data, so we only support setting one
+	 * page at a time.
+	 */
+	if (len > pg_len)
+		goto invalid_param;
+
+	return 0;
+
+ invalid_fld:
+	/* "Invalid field in CDB" */
+	ata_scsi_set_sense(scmd, ILLEGAL_REQUEST, 0x24, 0x0);
+	return 1;
+
+ invalid_param:
+	/* "Invalid field in parameter list" */
+	ata_scsi_set_sense(scmd, ILLEGAL_REQUEST, 0x26, 0x0);
+	return 1;
+
+ invalid_param_len:
+	/* "Parameter list length error" */
+	ata_scsi_set_sense(scmd, ILLEGAL_REQUEST, 0x1a, 0x0);
+	return 1;
+
+ skip:
+	scmd->result = SAM_STAT_GOOD;
+	return 1;
+}
+
+/**
  *	ata_get_xlat_func - check if SCSI to ATA translation is possible
  *	@dev: ATA device
  *	@cmd: SCSI command opcode to consider
@@ -3146,6 +3328,11 @@
 	case ATA_16:
 		return ata_scsi_pass_thru;
  
+	case MODE_SELECT:
+	case MODE_SELECT_10:
+		return ata_scsi_mode_select_xlat;
+		break;
+
 	case START_STOP:
 		return ata_scsi_start_stop_xlat;
 	}
@@ -3336,11 +3523,6 @@
 	case MODE_SENSE:
 	case MODE_SENSE_10:
 		ata_scsi_rbuf_fill(&args, ata_scsiop_mode_sense);
-		break;
-
-	case MODE_SELECT:	/* unconditionally return */
-	case MODE_SELECT_10:	/* bad-field-in-cdb */
-		ata_scsi_invalid_field(cmd);
 		break;
  
 	case READ_CAPACITY:
...	...	@@ -2243,7 +2243,7 @@
2243	2243	static unsigned int ata_msense_caching(u16 id, u8 buf, bool changeable)
2244	2244	{
2245	2245	modecpy(buf, def_cache_mpage, sizeof(def_cache_mpage), changeable);
2246		- if (!changeable && ata_id_wcache_enabled(id))
	2246	+ if (changeable \|\| ata_id_wcache_enabled(id))
2247	2247	buf[2] \|= (1 << 2); /* write cache enable */
2248	2248	if (!changeable && !ata_id_rahead_enabled(id))
2249	2249	buf[12] \|= (1 << 5); /* disable read ahead */
...	...	@@ -3107,6 +3107,188 @@
3107	3107	}
3108	3108
3109	3109	/**
	3110	+ * ata_mselect_caching - Simulate MODE SELECT for caching info page
	3111	+ * @qc: Storage for translated ATA taskfile
	3112	+ * @buf: input buffer
	3113	+ * @len: number of valid bytes in the input buffer
	3114	+ *
	3115	+ * Prepare a taskfile to modify caching information for the device.
	3116	+ *
	3117	+ * LOCKING:
	3118	+ * None.
	3119	+ */
	3120	+static int ata_mselect_caching(struct ata_queued_cmd *qc,
	3121	+ const u8 *buf, int len)
	3122	+{
	3123	+ struct ata_taskfile *tf = &qc->tf;
	3124	+ struct ata_device *dev = qc->dev;
	3125	+ char mpage[CACHE_MPAGE_LEN];
	3126	+ u8 wce;
	3127	+
	3128	+ /*
	3129	+ * The first two bytes of def_cache_mpage are a header, so offsets
	3130	+ * in mpage are off by 2 compared to buf. Same for len.
	3131	+ */
	3132	+
	3133	+ if (len != CACHE_MPAGE_LEN - 2)
	3134	+ return -EINVAL;
	3135	+
	3136	+ wce = buf[0] & (1 << 2);
	3137	+
	3138	+ /*
	3139	+ * Check that read-only bits are not modified.
	3140	+ */
	3141	+ ata_msense_caching(dev->id, mpage, false);
	3142	+ mpage[2] &= ~(1 << 2);
	3143	+ mpage[2] \|= wce;
	3144	+ if (memcmp(mpage + 2, buf, CACHE_MPAGE_LEN - 2) != 0)
	3145	+ return -EINVAL;
	3146	+
	3147	+ tf->flags \|= ATA_TFLAG_DEVICE \| ATA_TFLAG_ISADDR;
	3148	+ tf->protocol = ATA_PROT_NODATA;
	3149	+ tf->nsect = 0;
	3150	+ tf->command = ATA_CMD_SET_FEATURES;
	3151	+ tf->feature = wce ? SETFEATURES_WC_ON : SETFEATURES_WC_OFF;
	3152	+ return 0;
	3153	+}
	3154	+
	3155	+/**
	3156	+ * ata_scsiop_mode_select - Simulate MODE SELECT 6, 10 commands
	3157	+ * @qc: Storage for translated ATA taskfile
	3158	+ *
	3159	+ * Converts a MODE SELECT command to an ATA SET FEATURES taskfile.
	3160	+ * Assume this is invoked for direct access devices (e.g. disks) only.
	3161	+ * There should be no block descriptor for other device types.
	3162	+ *
	3163	+ * LOCKING:
	3164	+ * spin_lock_irqsave(host lock)
	3165	+ */
	3166	+static unsigned int ata_scsi_mode_select_xlat(struct ata_queued_cmd *qc)
	3167	+{
	3168	+ struct scsi_cmnd *scmd = qc->scsicmd;
	3169	+ const u8 *cdb = scmd->cmnd;
	3170	+ const u8 *p;
	3171	+ u8 pg, spg;
	3172	+ unsigned six_byte, pg_len, hdr_len, bd_len;
	3173	+ int len;
	3174	+
	3175	+ VPRINTK("ENTER\n");
	3176	+
	3177	+ six_byte = (cdb[0] == MODE_SELECT);
	3178	+ if (six_byte) {
	3179	+ if (scmd->cmd_len < 5)
	3180	+ goto invalid_fld;
	3181	+
	3182	+ len = cdb[4];
	3183	+ hdr_len = 4;
	3184	+ } else {
	3185	+ if (scmd->cmd_len < 9)
	3186	+ goto invalid_fld;
	3187	+
	3188	+ len = (cdb[7] << 8) + cdb[8];
	3189	+ hdr_len = 8;
	3190	+ }
	3191	+
	3192	+ /* We only support PF=1, SP=0. */
	3193	+ if ((cdb[1] & 0x11) != 0x10)
	3194	+ goto invalid_fld;
	3195	+
	3196	+ /* Test early for possible overrun. */
	3197	+ if (!scsi_sg_count(scmd) \|\| scsi_sglist(scmd)->length < len)
	3198	+ goto invalid_param_len;
	3199	+
	3200	+ p = page_address(sg_page(scsi_sglist(scmd)));
	3201	+
	3202	+ /* Move past header and block descriptors. */
	3203	+ if (len < hdr_len)
	3204	+ goto invalid_param_len;
	3205	+
	3206	+ if (six_byte)
	3207	+ bd_len = p[3];
	3208	+ else
	3209	+ bd_len = (p[6] << 8) + p[7];
	3210	+
	3211	+ len -= hdr_len;
	3212	+ p += hdr_len;
	3213	+ if (len < bd_len)
	3214	+ goto invalid_param_len;
	3215	+ if (bd_len != 0 && bd_len != 8)
	3216	+ goto invalid_param;
	3217	+
	3218	+ len -= bd_len;
	3219	+ p += bd_len;
	3220	+ if (len == 0)
	3221	+ goto skip;
	3222	+
	3223	+ /* Parse both possible formats for the mode page headers. */
	3224	+ pg = p[0] & 0x3f;
	3225	+ if (p[0] & 0x40) {
	3226	+ if (len < 4)
	3227	+ goto invalid_param_len;
	3228	+
	3229	+ spg = p[1];
	3230	+ pg_len = (p[2] << 8) \| p[3];
	3231	+ p += 4;
	3232	+ len -= 4;
	3233	+ } else {
	3234	+ if (len < 2)
	3235	+ goto invalid_param_len;
	3236	+
	3237	+ spg = 0;
	3238	+ pg_len = p[1];
	3239	+ p += 2;
	3240	+ len -= 2;
	3241	+ }
	3242	+
	3243	+ /*
	3244	+ * No mode subpages supported (yet) but asking for _all_
	3245	+ * subpages may be valid
	3246	+ */
	3247	+ if (spg && (spg != ALL_SUB_MPAGES))
	3248	+ goto invalid_param;
	3249	+ if (pg_len > len)
	3250	+ goto invalid_param_len;
	3251	+
	3252	+ switch (pg) {
	3253	+ case CACHE_MPAGE:
	3254	+ if (ata_mselect_caching(qc, p, pg_len) < 0)
	3255	+ goto invalid_param;
	3256	+ break;
	3257	+
	3258	+ default: /* invalid page code */
	3259	+ goto invalid_param;
	3260	+ }
	3261	+
	3262	+ /*
	3263	+ * Only one page has changeable data, so we only support setting one
	3264	+ * page at a time.
	3265	+ */
	3266	+ if (len > pg_len)
	3267	+ goto invalid_param;
	3268	+
	3269	+ return 0;
	3270	+
	3271	+ invalid_fld:
	3272	+ /* "Invalid field in CDB" */
	3273	+ ata_scsi_set_sense(scmd, ILLEGAL_REQUEST, 0x24, 0x0);
	3274	+ return 1;
	3275	+
	3276	+ invalid_param:
	3277	+ /* "Invalid field in parameter list" */
	3278	+ ata_scsi_set_sense(scmd, ILLEGAL_REQUEST, 0x26, 0x0);
	3279	+ return 1;
	3280	+
	3281	+ invalid_param_len:
	3282	+ /* "Parameter list length error" */
	3283	+ ata_scsi_set_sense(scmd, ILLEGAL_REQUEST, 0x1a, 0x0);
	3284	+ return 1;
	3285	+
	3286	+ skip:
	3287	+ scmd->result = SAM_STAT_GOOD;
	3288	+ return 1;
	3289	+}
	3290	+
	3291	+/**
3110	3292	* ata_get_xlat_func - check if SCSI to ATA translation is possible
3111	3293	* @dev: ATA device
3112	3294	* @cmd: SCSI command opcode to consider
...	...	@@ -3146,6 +3328,11 @@
3146	3328	case ATA_16:
3147	3329	return ata_scsi_pass_thru;
3148	3330
	3331	+ case MODE_SELECT:
	3332	+ case MODE_SELECT_10:
	3333	+ return ata_scsi_mode_select_xlat;
	3334	+ break;
	3335	+
3149	3336	case START_STOP:
3150	3337	return ata_scsi_start_stop_xlat;
3151	3338	}
...	...	@@ -3336,11 +3523,6 @@
3336	3523	case MODE_SENSE:
3337	3524	case MODE_SENSE_10:
3338	3525	ata_scsi_rbuf_fill(&args, ata_scsiop_mode_sense);
3339		- break;
3340		-
3341		- case MODE_SELECT: /* unconditionally return */
3342		- case MODE_SELECT_10: /* bad-field-in-cdb */
3343		- ata_scsi_invalid_field(cmd);
3344	3526	break;
3345	3527
3346	3528	case READ_CAPACITY: