Re: [PATCH 3/4] target/rd: T10-Dif: Add init/format support

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On 3/29/2014 2:05 AM, Quinn Tran wrote:
This patch is borrow code from

commit 0f5e2ec46dd64579c0770f3822764f94db4fa465
Author: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Date:   Sat Jan 18 09:32:56 2014 +0000

     target/file: Add DIF protection init/format support

     This patch adds support for DIF protection init/format support into
     the FILEIO backend.

     It involves using a seperate $FILE.protection for storing PI that is
     opened via fd_init_prot() using the common pi_prot_type attribute.
     The actual formatting of the protection is done via fd_format_prot()
     using the common pi_prot_format attribute, that will populate the
     initial PI data based upon the currently configured pi_prot_type.

     Based on original FILEIO code from Sagi.

     v1 changes:
       - Fix sparse warnings in fd_init_format_buf (Fengguang)

     Cc: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
     Cc: Christoph Hellwig <hch@xxxxxx>
     Cc: Hannes Reinecke <hare@xxxxxxx>
     Cc: Sagi Grimberg <sagig@xxxxxxxxxxxx>
     Cc: Or Gerlitz <ogerlitz@xxxxxxxxxxxx>
     Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
---
  drivers/target/target_core_rd.c | 64 ++++++++++++++++++++++++++++++++++++++++-
  1 file changed, 63 insertions(+), 1 deletion(-)

diff --git a/drivers/target/target_core_rd.c b/drivers/target/target_core_rd.c
index 66a5aba..01dda0b 100644
--- a/drivers/target/target_core_rd.c
+++ b/drivers/target/target_core_rd.c
@@ -603,7 +603,7 @@ static int rd_init_prot(struct se_device *dev)
  {
  	struct rd_dev *rd_dev = RD_DEV(dev);
- if (!dev->dev_attrib.pi_prot_type)
+	if (!dev->dev_attrib.pi_prot_type)
  		return 0;
return rd_build_prot_space(rd_dev, dev->prot_length);
@@ -616,6 +616,67 @@ static void rd_free_prot(struct se_device *dev)
  	rd_release_prot_space(rd_dev);
  }
+static void rd_init_format_buf(struct se_device *dev, unsigned char *buf,
+			       u32 unit_size, u32 *ref_tag, u16 app_tag,
+			       bool inc_reftag)
+{
+	unsigned char *p = buf;
+	int i;
+
+	for (i = 0; i < unit_size; i += dev->prot_length) {
+		*((u16 *)&p[0]) = 0xffff;
+		*((__be16 *)&p[2]) = cpu_to_be16(app_tag);
+		*((__be32 *)&p[4]) = cpu_to_be32(*ref_tag);
+
+		if (inc_reftag)
+			(*ref_tag)++;
+
+		p += dev->prot_length;
+	}
+}
+
+static int rd_format_prot(struct se_device *dev)
+{
+	struct rd_dev *rd_dev = RD_DEV(dev);
+	u32 ref_tag = 0;
+	int i,j;
+	bool inc_reftag = false;
+	struct rd_dev_sg_table *pt;
+	struct scatterlist *sg;
+	void *paddr;
+
+	if (!dev->dev_attrib.pi_prot_type) {
+		pr_err("Unable to format_prot while pi_prot_type == 0\n");
+		return -ENODEV;
+	}
+
+	switch (dev->dev_attrib.pi_prot_type) {
+	case TARGET_DIF_TYPE3_PROT:
+		ref_tag = 0xffffffff;
+		break;
+	case TARGET_DIF_TYPE2_PROT:
+	case TARGET_DIF_TYPE1_PROT:
+		inc_reftag = true;
+		break;
+	default:
+		break;
+	}
+
+	for (i=0; i < rd_dev->sg_prot_count; i++) {
+		pt= &rd_dev->sg_prot_array[i];
+		for_each_sg(pt->sg_table, sg, pt->rd_sg_count, j) {
+			paddr = kmap(sg_page(sg)) + sg->offset;
+
+			rd_init_format_buf(dev, paddr, sg->length, &ref_tag,
+					0xffff, inc_reftag);
+			kunmap(paddr);
+		}
+	}
+
+	return 0;
+}
+
+
  static struct sbc_ops rd_sbc_ops = {
  	.execute_rw		= rd_execute_rw,
  };
@@ -642,6 +703,7 @@ static struct se_subsystem_api rd_mcp_template = {
  	.get_device_type	= sbc_get_device_type,
  	.get_blocks		= rd_get_blocks,
  	.init_prot		= rd_init_prot,
+	.format_prot            = rd_format_prot,
  	.free_prot		= rd_free_prot,
  };

This patch is redundant altogether. rd_mcp already init protection with escape values:
rc = rd_allocate_sgl_table(rd_dev, sg_table, total_sg_needed, 0xff);
--
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