UBI: allow direct user-space I/O

Introduce a new ioctl UBI_IOCSETPROP to set properties
on a volume. Also add the first property:
UBI_PROP_DIRECT_WRITE, this property is used to set the
ability to use direct writes in userspace

Signed-off-by: Sidney Amani <seed@uffs.org>
Signed-off-by: Corentin Chary <corentincj@iksaif.net>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

1 files changed, 28 insertions, 8 deletions

diff --git a/drivers/mtd/ubi/cdev.c b/drivers/mtd/ubi/cdev.c
index f9631eb3fef3..e63c8fc3df3a 100644
--- a/drivers/mtd/ubi/cdev.c
+++ b/drivers/mtd/ubi/cdev.c
@@ -259,12 +259,9 @@ static ssize_t vol_cdev_read(struct file *file, __user char *buf, size_t count,
         return err ? err : count_save - count;
 }
 
-#ifdef CONFIG_MTD_UBI_DEBUG_USERSPACE_IO
-
 /*
  * This function allows to directly write to dynamic UBI volumes, without
- * issuing the volume update operation. Available only as a debugging feature.
- * Very useful for testing UBI.
+ * issuing the volume update operation.
  */
 static ssize_t vol_cdev_direct_write(struct file *file, const char __user *buf,
                                      size_t count, loff_t *offp)
@@ -276,6 +273,9 @@ static ssize_t vol_cdev_direct_write(struct file *file, const char __user *buf,
         size_t count_save = count;
         char *tbuf;
 
+        if (!vol->direct_writes)
+                return -EPERM;
+
         dbg_gen("requested: write %zd bytes to offset %lld of volume %u",
                 count, *offp, vol->vol_id);
 
@@ -339,10 +339,6 @@ static ssize_t vol_cdev_direct_write(struct file *file, const char __user *buf,
         return err ? err : count_save - count;
 }
 
-#else
-#define vol_cdev_direct_write(file, buf, count, offp) (-EPERM)
-#endif /* CONFIG_MTD_UBI_DEBUG_USERSPACE_IO */
-
 static ssize_t vol_cdev_write(struct file *file, const char __user *buf,
                               size_t count, loff_t *offp)
 {
@@ -552,6 +548,30 @@ static long vol_cdev_ioctl(struct file *file, unsigned int cmd,
                 break;
         }
 
+        /* Set volume property command*/
+        case UBI_IOCSETPROP:
+        {
+                struct ubi_set_prop_req req;
+
+                err = copy_from_user(&req, argp,
+                                sizeof(struct ubi_set_prop_req));
+                if (err) {
+                        err = -EFAULT;
+                        break;
+                }
+                switch (req.property) {
+                case UBI_PROP_DIRECT_WRITE:
+                        mutex_lock(&ubi->volumes_mutex);
+                        desc->vol->direct_writes = !!req.value;
+                        mutex_unlock(&ubi->volumes_mutex);
+                        break;
+                default:
+                        err = -EINVAL;
+                        break;
+                }
+                break;
+        }
+
         default:
                 err = -ENOTTY;
                 break;