scsi: target: Add callout to configure UNMAP settings

Add a callout to configure a backend's UNMAP settings. This will be used to
allow userspace to configure UNMAP after the initial device setup, similar
to how we can set up the other attributes post device configuration.

Link: https://lore.kernel.org/r/20220628200230.15052-3-michael.christie@oracle.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index 25f33eb..086ac9c 100644 (file)
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -960,6 +960,12 @@ int target_configure_device(struct se_device *dev)
        ret = dev->transport->configure_device(dev);
        if (ret)
                goto out_free_index;
+
+       if (dev->transport->configure_unmap &&
+           dev->transport->configure_unmap(dev)) {
+               pr_debug("Discard support available, but disabled by default.\n");
+       }
+
        /*
         * XXX: there is not much point to have two different values here..
         */

diff --git a/include/target/target_core_backend.h b/include/target/target_core_backend.h
index 773963a..a3c193d 100644 (file)
--- a/include/target/target_core_backend.h
+++ b/include/target/target_core_backend.h
@@ -37,6 +37,7 @@ struct target_backend_ops {
        struct se_dev_plug *(*plug_device)(struct se_device *se_dev);
        void (*unplug_device)(struct se_dev_plug *se_plug);
 
+       bool (*configure_unmap)(struct se_device *se_dev);
        ssize_t (*set_configfs_dev_params)(struct se_device *,
                                           const char *, ssize_t);
        ssize_t (*show_configfs_dev_params)(struct se_device *, char *);