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Commit d0c8b259 authored by Nicholas Bellinger's avatar Nicholas Bellinger
Browse files

target/iblock: Use backend REQ_FLUSH hint for WriteCacheEnabled status 



This patch allows IBLOCK to check block hints in request_queue->flush_flags
when reporting current backend device WriteCacheEnabled status to a remote
SCSI initiator port.

This is done via a se_subsystem_api->get_write_cache() call instead of a
backend se_device creation time flag, as we expect REQ_FLUSH bits to possibly
change from an underlying blk_queue_flush() by the SCSI disk driver, or
internal raw struct block_device driver usage.

Also go ahead and update iblock_execute_rw() bio I/O path code to use
REQ_FLUSH + REQ_FUA hints when determining WRITE_FUA usage, and make SPC
emulation code use a spc_check_dev_wce() helper to handle both types of
cases for virtual backend subsystem drivers.

(asias: Drop unnecessary comparsion operators)

Reported-by: default avatarmajianpeng <majianpeng@gmail.com>
Cc: majianpeng <majianpeng@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 1be2956d

drivers/target/target_core_device.c

+6 −0
Original line number Original line Diff line number Diff line
@@ -772,6 +772,12 @@ int se_dev_set_emulate_write_cache(struct se_device *dev, int flag) 
		pr_err("emulate_write_cache not supported for pSCSI\n");

		pr_err("emulate_write_cache not supported for pSCSI\n");

		return -EINVAL;

		return -EINVAL;

	}

	}

	if (dev->transport->get_write_cache) {

		pr_warn("emulate_write_cache cannot be changed when underlying"

			" HW reports WriteCacheEnabled, ignoring request\n");

		return 0;

	}



	dev->dev_attrib.emulate_write_cache = flag;

	dev->dev_attrib.emulate_write_cache = flag;

	pr_debug("dev[%p]: SE Device WRITE_CACHE_EMULATION flag: %d\n",

	pr_debug("dev[%p]: SE Device WRITE_CACHE_EMULATION flag: %d\n",

			dev, dev->dev_attrib.emulate_write_cache);

			dev, dev->dev_attrib.emulate_write_cache);

drivers/target/target_core_iblock.c

+23 −8
Original line number Original line Diff line number Diff line
@@ -154,6 +154,7 @@ static int iblock_configure_device(struct se_device *dev) 




	if (blk_queue_nonrot(q))

	if (blk_queue_nonrot(q))

		dev->dev_attrib.is_nonrot = 1;

		dev->dev_attrib.is_nonrot = 1;



	return 0;

	return 0;





out_free_bioset:

out_free_bioset:
@@ -654,20 +655,24 @@ iblock_execute_rw(struct se_cmd *cmd) 
	u32 sg_num = sgl_nents;

	u32 sg_num = sgl_nents;

	sector_t block_lba;

	sector_t block_lba;

	unsigned bio_cnt;

	unsigned bio_cnt;

	int rw;

	int rw = 0;

	int i;

	int i;





	if (data_direction == DMA_TO_DEVICE) {

	if (data_direction == DMA_TO_DEVICE) {

		struct iblock_dev *ib_dev = IBLOCK_DEV(dev);

		struct request_queue *q = bdev_get_queue(ib_dev->ibd_bd);

		/*

		/*

		 * Force data to disk if we pretend to not have a volatile

		 * Force writethrough using WRITE_FUA if a volatile write cache

		 * write cache, or the initiator set the Force Unit Access bit.

		 * is not enabled, or if initiator set the Force Unit Access bit.

		 */

		 */

		if (dev->dev_attrib.emulate_write_cache == 0 ||

		if (q->flush_flags & REQ_FUA) {

		    (dev->dev_attrib.emulate_fua_write > 0 &&

			if (cmd->se_cmd_flags & SCF_FUA)

		     (cmd->se_cmd_flags & SCF_FUA)))

				rw = WRITE_FUA;

				rw = WRITE_FUA;

		else

			else if (!(q->flush_flags & REQ_FLUSH))

				rw = WRITE_FUA;

		} else {

			rw = WRITE;

			rw = WRITE;

		}

	} else {

	} else {

		rw = READ;

		rw = READ;

	}

	}
@@ -774,6 +779,15 @@ iblock_parse_cdb(struct se_cmd *cmd) 
	return sbc_parse_cdb(cmd, &iblock_sbc_ops);

	return sbc_parse_cdb(cmd, &iblock_sbc_ops);

}

}





bool iblock_get_write_cache(struct se_device *dev)

{

	struct iblock_dev *ib_dev = IBLOCK_DEV(dev);

	struct block_device *bd = ib_dev->ibd_bd;

	struct request_queue *q = bdev_get_queue(bd);



	return q->flush_flags & REQ_FLUSH;

}



static struct se_subsystem_api iblock_template = {

static struct se_subsystem_api iblock_template = {

	.name			= "iblock",

	.name			= "iblock",

	.inquiry_prod		= "IBLOCK",

	.inquiry_prod		= "IBLOCK",
@@ -790,6 +804,7 @@ static struct se_subsystem_api iblock_template = { 
	.show_configfs_dev_params = iblock_show_configfs_dev_params,

	.show_configfs_dev_params = iblock_show_configfs_dev_params,

	.get_device_type	= sbc_get_device_type,

	.get_device_type	= sbc_get_device_type,

	.get_blocks		= iblock_get_blocks,

	.get_blocks		= iblock_get_blocks,

	.get_write_cache	= iblock_get_write_cache,

};

};





static int __init iblock_module_init(void)

static int __init iblock_module_init(void)

drivers/target/target_core_spc.c

+18 −3
Original line number Original line Diff line number Diff line
@@ -407,16 +407,31 @@ check_scsi_name: 
}

}

EXPORT_SYMBOL(spc_emulate_evpd_83);

EXPORT_SYMBOL(spc_emulate_evpd_83);





static bool

spc_check_dev_wce(struct se_device *dev)

{

	bool wce = false;



	if (dev->transport->get_write_cache)

		wce = dev->transport->get_write_cache(dev);

	else if (dev->dev_attrib.emulate_write_cache > 0)

		wce = true;



	return wce;

}



/* Extended INQUIRY Data VPD Page */

/* Extended INQUIRY Data VPD Page */

static sense_reason_t

static sense_reason_t

spc_emulate_evpd_86(struct se_cmd *cmd, unsigned char *buf)

spc_emulate_evpd_86(struct se_cmd *cmd, unsigned char *buf)

{

{

	struct se_device *dev = cmd->se_dev;



	buf[3] = 0x3c;

	buf[3] = 0x3c;

	/* Set HEADSUP, ORDSUP, SIMPSUP */

	/* Set HEADSUP, ORDSUP, SIMPSUP */

	buf[5] = 0x07;

	buf[5] = 0x07;





	/* If WriteCache emulation is enabled, set V_SUP */

	/* If WriteCache emulation is enabled, set V_SUP */

	if (cmd->se_dev->dev_attrib.emulate_write_cache > 0)

	if (spc_check_dev_wce(dev))

		buf[6] = 0x01;

		buf[6] = 0x01;

	return 0;

	return 0;

}

}
@@ -766,7 +781,7 @@ static int spc_modesense_caching(struct se_device *dev, u8 pc, u8 *p) 
	if (pc == 1)

	if (pc == 1)

		goto out;

		goto out;





	if (dev->dev_attrib.emulate_write_cache > 0)

	if (spc_check_dev_wce(dev))

		p[2] = 0x04; /* Write Cache Enable */

		p[2] = 0x04; /* Write Cache Enable */

	p[12] = 0x20; /* Disabled Read Ahead */

	p[12] = 0x20; /* Disabled Read Ahead */
@@ -878,7 +893,7 @@ static sense_reason_t spc_emulate_modesense(struct se_cmd *cmd) 
	     (cmd->se_deve->lun_flags & TRANSPORT_LUNFLAGS_READ_ONLY)))

	     (cmd->se_deve->lun_flags & TRANSPORT_LUNFLAGS_READ_ONLY)))

		spc_modesense_write_protect(&buf[length], type);

		spc_modesense_write_protect(&buf[length], type);





	if ((dev->dev_attrib.emulate_write_cache > 0) &&

	if ((spc_check_dev_wce(dev)) &&

	    (dev->dev_attrib.emulate_fua_write > 0))

	    (dev->dev_attrib.emulate_fua_write > 0))

		spc_modesense_dpofua(&buf[length], type);

		spc_modesense_dpofua(&buf[length], type);

include/target/target_core_backend.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -35,6 +35,7 @@ struct se_subsystem_api { 
	u32 (*get_device_type)(struct se_device *);

	u32 (*get_device_type)(struct se_device *);

	sector_t (*get_blocks)(struct se_device *);

	sector_t (*get_blocks)(struct se_device *);

	unsigned char *(*get_sense_buffer)(struct se_cmd *);

	unsigned char *(*get_sense_buffer)(struct se_cmd *);

	bool (*get_write_cache)(struct se_device *);

};

};





struct sbc_ops {

struct sbc_ops {