Sorry for the ungodly subject length (and this top post, which seems appropriate given the circumstances). I have been using subversion a lot recently and so I forgot to leave a separate brief line in the git commit message. I have already amended locally. Please let me know if I should retransmit and start over with a new thread.
________________________________________
From: Jamie Pocas [jamie.pocas@xxxxxxx]
Sent: Thursday, November 19, 2015 7:09 AM
To: target-devel@xxxxxxxxxxxxxxx
Cc: Pocas, Jamie
Subject: [PATCH] This change sets the LBPRZ flag in EVPD page b2h and READ CAPACITY (16) based on a new unmap_zeroes_data device attribute. This flag is set automatically for iblock based on underlying block device queue's discard_zeroes_data flag.
Signed-off-by: Jamie Pocas <jamie.pocas@xxxxxxx>
---
drivers/target/target_core_configfs.c | 36 +++++++++++++++++++++++++++++++++++
drivers/target/target_core_device.c | 2 ++
drivers/target/target_core_iblock.c | 2 ++
drivers/target/target_core_sbc.c | 10 +++++++++-
drivers/target/target_core_spc.c | 12 ++++++++++++
include/target/target_core_base.h | 3 +++
6 files changed, 64 insertions(+), 1 deletion(-)
diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
index 860e840..dfb50ea 100644
--- a/drivers/target/target_core_configfs.c
+++ b/drivers/target/target_core_configfs.c
@@ -511,6 +511,7 @@ DEF_TB_DEV_ATTRIB_SHOW(max_unmap_lba_count);
DEF_TB_DEV_ATTRIB_SHOW(max_unmap_block_desc_count);
DEF_TB_DEV_ATTRIB_SHOW(unmap_granularity);
DEF_TB_DEV_ATTRIB_SHOW(unmap_granularity_alignment);
+DEF_TB_DEV_ATTRIB_SHOW(unmap_zeroes_data);
DEF_TB_DEV_ATTRIB_SHOW(max_write_same_len);
#define DEF_TB_DEV_ATTRIB_STORE_U32(_name) \
@@ -866,6 +867,39 @@ static ssize_t store_emulate_rest_reord(struct se_dev_attrib *da,
return count;
}
+static ssize_t store_unmap_zeroes_data(struct se_dev_attrib *da,
+ const char *page, size_t count)
+{
+ bool flag;
+ int ret;
+
+ ret = strtobool(page, &flag);
+ if (ret < 0)
+ return ret;
+
+ if (da->da_dev->export_count) {
+ pr_err("dev[%p]: Unable to change SE Device"
+ " unmap_zeroes_data while export_count is %d\n",
+ da->da_dev, da->da_dev->export_count);
+ return -EINVAL;
+ }
+ /*
+ * We expect this value to be non-zero when generic Block Layer
+ * Discard supported is detected iblock_configure_device().
+ */
+ if (flag && !da->max_unmap_block_desc_count) {
+ pr_err("dev[%p]: Thin Provisioning LBPRZ will not be set"
+ "because max_unmap_block_desc_count is zero\n",
+ da->da_dev);
+ return -ENOSYS;
+ }
+ da->unmap_zeroes_data = flag;
+ pr_debug("dev[%p]: SE Device Thin Provisioning LBPRZ bit: %d\n",
+ da->da_dev, flag);
+ return 0;
+}
+
+
/*
* Note, this can only be called on unexported SE Device Object.
*/
@@ -1007,6 +1041,7 @@ TB_DEV_ATTR(target_core, max_unmap_lba_count, S_IRUGO | S_IWUSR);
TB_DEV_ATTR(target_core, max_unmap_block_desc_count, S_IRUGO | S_IWUSR);
TB_DEV_ATTR(target_core, unmap_granularity, S_IRUGO | S_IWUSR);
TB_DEV_ATTR(target_core, unmap_granularity_alignment, S_IRUGO | S_IWUSR);
+TB_DEV_ATTR(target_core, unmap_zeroes_data, S_IRUGO | S_IWUSR);
TB_DEV_ATTR(target_core, max_write_same_len, S_IRUGO | S_IWUSR);
CONFIGFS_EATTR_STRUCT(target_core_dev_attrib, se_dev_attrib);
@@ -1046,6 +1081,7 @@ struct configfs_attribute *sbc_attrib_attrs[] = {
&target_core_dev_attrib_max_unmap_block_desc_count.attr,
&target_core_dev_attrib_unmap_granularity.attr,
&target_core_dev_attrib_unmap_granularity_alignment.attr,
+ &target_core_dev_attrib_unmap_zeroes_data.attr,
&target_core_dev_attrib_max_write_same_len.attr,
NULL,
};
diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index 09e682b..65d3b5a 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -809,6 +809,8 @@ struct se_device *target_alloc_device(struct se_hba *hba, const char *name)
dev->dev_attrib.unmap_granularity = DA_UNMAP_GRANULARITY_DEFAULT;
dev->dev_attrib.unmap_granularity_alignment =
DA_UNMAP_GRANULARITY_ALIGNMENT_DEFAULT;
+ dev->dev_attrib.unmap_zeroes_data =
+ DA_UNMAP_ZEROES_DATA_DEFAULT;
dev->dev_attrib.max_write_same_len = DA_MAX_WRITE_SAME_LEN;
xcopy_lun = &dev->xcopy_lun;
diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
index 5a9982f..a41bbdc 100644
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -136,6 +136,8 @@ static int iblock_configure_device(struct se_device *dev)
q->limits.discard_granularity >> 9;
dev->dev_attrib.unmap_granularity_alignment =
q->limits.discard_alignment;
+ dev->dev_attrib.unmap_zeroes_data =
+ q->limits.discard_zeroes_data;
pr_debug("IBLOCK: BLOCK Discard support available,"
" disabled by default\n");
diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c
index e318ddb..4b18254 100644
--- a/drivers/target/target_core_sbc.c
+++ b/drivers/target/target_core_sbc.c
@@ -141,9 +141,17 @@ sbc_emulate_readcapacity_16(struct se_cmd *cmd)
* Set Thin Provisioning Enable bit following sbc3r22 in section
* READ CAPACITY (16) byte 14 if emulate_tpu or emulate_tpws is enabled.
*/
- if (dev->dev_attrib.emulate_tpu || dev->dev_attrib.emulate_tpws)
+ if (dev->dev_attrib.emulate_tpu || dev->dev_attrib.emulate_tpws) {
buf[14] |= 0x80;
+ /*
+ * LBPRZ signifies that zeroes will be read back from an LBA after
+ * an UNMAP or WRITE SAME w/ unmap bit (sbc3r36 5.16.2)
+ */
+ if (dev->dev_attrib.unmap_zeroes_data)
+ buf[14] |= 0x40;
+ }
+
rbuf = transport_kmap_data_sg(cmd);
if (rbuf) {
memcpy(rbuf, buf, min_t(u32, sizeof(buf), cmd->data_length));
diff --git a/drivers/target/target_core_spc.c b/drivers/target/target_core_spc.c
index f87d4ce..440322d 100644
--- a/drivers/target/target_core_spc.c
+++ b/drivers/target/target_core_spc.c
@@ -628,6 +628,18 @@ spc_emulate_evpd_b2(struct se_cmd *cmd, unsigned char *buf)
if (dev->dev_attrib.emulate_tpws != 0)
buf[5] |= 0x40 | 0x20;
+ /*
+ * The unmap_zeroes_data set means that the underlying device supports
+ * REQ_DISCARD and has the discard_zeroes_data bit set. This satisfies
+ * the SBC requirements for LBPRZ, meaning that a subsequent read
+ * will return zeroes after an UNMAP or WRITE SAME (16) to an LBA
+ * See sbc4r36 6.6.4.
+ */
+ if (((dev->dev_attrib.emulate_tpu != 0) |
+ (dev->dev_attrib.emulate_tpws != 0)) &&
+ (dev->dev_attrib.unmap_zeroes_data != 0))
+ buf[5] |= 0x04;
+
return 0;
}
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 17ae2d6..a6371d4 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -62,6 +62,8 @@
#define DA_UNMAP_GRANULARITY_DEFAULT 0
/* Default unmap_granularity_alignment */
#define DA_UNMAP_GRANULARITY_ALIGNMENT_DEFAULT 0
+/* Default unmap_zeroes_data */
+#define DA_UNMAP_ZEROES_DATA_DEFAULT 0
/* Default max_write_same_len, disabled by default */
#define DA_MAX_WRITE_SAME_LEN 0
/* Use a model alias based on the configfs backend device name */
@@ -651,6 +653,7 @@ struct se_dev_attrib {
int force_pr_aptpl;
int is_nonrot;
int emulate_rest_reord;
+ int unmap_zeroes_data;
u32 hw_block_size;
u32 block_size;
u32 hw_max_sectors;
--
1.8.3.1
--
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