target: do not reject FUA CDBs when write cache is enabled but emulate_write_cache...

A check that rejects a CDB with FUA bit set if no write cache is
emulated was added by the following commit:

  fde9f50 target: Add sanity checks for DPO/FUA bit usage

The condition is as follows:

  if (!dev->dev_attrib.emulate_fua_write ||
      !dev->dev_attrib.emulate_write_cache)

However, this check is wrong if the backend device supports WCE but
"emulate_write_cache" is disabled.

This patch uses se_dev_check_wce() (previously named
spc_check_dev_wce) to invoke transport->get_write_cache() if the
device has a write cache or check the "emulate_write_cache" attribute
otherwise.

Reported-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christophe Vu-Brugier <cvubrugier@fastmail.fm>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index 7fc5eae875de9c6597cdc3d477d75379cf9d025f..79b4ec3ca2db12416a692fba785a09b462e3169f 100644 (file)
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -650,6 +650,18 @@ static u32 se_dev_align_max_sectors(u32 max_sectors, u32 block_size)
        return aligned_max_sectors;
 }
 
+bool se_dev_check_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;
+}
+
 int se_dev_set_max_unmap_lba_count(
        struct se_device *dev,
        u32 max_unmap_lba_count)

diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c
index 9a2f9d3a6e70514ad9351ab6e144709e8b95f91d..3e729741111075cf4828a46ac2f434414e70faf1 100644 (file)
--- a/drivers/target/target_core_sbc.c
+++ b/drivers/target/target_core_sbc.c
@@ -708,8 +708,7 @@ sbc_check_dpofua(struct se_device *dev, struct se_cmd *cmd, unsigned char *cdb)
                }
        }
        if (cdb[1] & 0x8) {
-               if (!dev->dev_attrib.emulate_fua_write ||
-                   !dev->dev_attrib.emulate_write_cache) {
+               if (!dev->dev_attrib.emulate_fua_write || !se_dev_check_wce(dev)) {
                        pr_err("Got CDB: 0x%02x with FUA bit set, but device"
                               " does not advertise support for FUA write\n",
                               cdb[0]);

diff --git a/drivers/target/target_core_spc.c b/drivers/target/target_core_spc.c
index 460e9310947399661ce1fbd6ab4ed3e86b4a47e1..6c8bd6bc175ca48fb9d33063dc3f3b8185d19876 100644 (file)
--- a/drivers/target/target_core_spc.c
+++ b/drivers/target/target_core_spc.c
@@ -454,19 +454,6 @@ check_scsi_name:
 }
 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 */
 static sense_reason_t
 spc_emulate_evpd_86(struct se_cmd *cmd, unsigned char *buf)
@@ -490,7 +477,7 @@ spc_emulate_evpd_86(struct se_cmd *cmd, unsigned char *buf)
        buf[5] = 0x07;
 
        /* If WriteCache emulation is enabled, set V_SUP */
-       if (spc_check_dev_wce(dev))
+       if (se_dev_check_wce(dev))
                buf[6] = 0x01;
        /* If an LBA map is present set R_SUP */
        spin_lock(&cmd->se_dev->t10_alua.lba_map_lock);
@@ -897,7 +884,7 @@ static int spc_modesense_caching(struct se_cmd *cmd, u8 pc, u8 *p)
        if (pc == 1)
                goto out;
 
-       if (spc_check_dev_wce(dev))
+       if (se_dev_check_wce(dev))
                p[2] = 0x04; /* Write Cache Enable */
        p[12] = 0x20; /* Disabled Read Ahead */
 
@@ -1009,7 +996,7 @@ static sense_reason_t spc_emulate_modesense(struct se_cmd *cmd)
             (cmd->se_deve->lun_flags & TRANSPORT_LUNFLAGS_READ_ONLY)))
                spc_modesense_write_protect(&buf[length], type);
 
-       if ((spc_check_dev_wce(dev)) &&
+       if ((se_dev_check_wce(dev)) &&
            (dev->dev_attrib.emulate_fua_write > 0))
                spc_modesense_dpofua(&buf[length], type);
 

diff --git a/include/target/target_core_backend.h b/include/target/target_core_backend.h
index db81c65b8f4857c011a025e5b54026bf7d683f7c..d61be7297b2c88c867acbacadcacfd65045e6c50 100644 (file)
--- a/include/target/target_core_backend.h
+++ b/include/target/target_core_backend.h
@@ -111,6 +111,7 @@ void        array_free(void *array, int n);
 void   target_core_setup_sub_cits(struct se_subsystem_api *);
 
 /* attribute helpers from target_core_device.c for backend drivers */
+bool   se_dev_check_wce(struct se_device *);
 int    se_dev_set_max_unmap_lba_count(struct se_device *, u32);
 int    se_dev_set_max_unmap_block_desc_count(struct se_device *, u32);
 int    se_dev_set_unmap_granularity(struct se_device *, u32);