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>

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>
Sidney Amani · Artem Bityutskiy
1 parent 36b477d005
Showing 4 changed files with 66 additions and 19 deletions Side-by-side Diff
drivers/mtd/ubi/Kconfig.debug
drivers/mtd/ubi/cdev.c
drivers/mtd/ubi/ubi.h
include/mtd/ubi-user.h
@@ -33,16 +33,6 @@
 	  This option switches the background thread off by default. The thread
 	  may be also be enabled/disabled via UBI sysfs.
  
-config MTD_UBI_DEBUG_USERSPACE_IO
-	bool "Direct user-space write/erase support"
-	default n
-	depends on MTD_UBI_DEBUG
-	help
-	  By default, users cannot directly write and erase individual
-	  eraseblocks of dynamic volumes, and have to use update operation
-	  instead. This option enables this capability - it is very useful for
-	  debugging and testing.
-
 config MTD_UBI_DEBUG_EMULATE_BITFLIPS
 	bool "Emulate flash bit-flips"
 	depends on MTD_UBI_DEBUG
@@ -259,12 +259,9 @@
 	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 @@
 	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 @@
 	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)
 {
@@ -549,6 +545,30 @@
 			break;
 		}
 		err = ubi_is_mapped(desc, lnum);
+		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;
 	}
  
@@ -206,6 +206,7 @@
  * @upd_marker: %1 if the update marker is set for this volume
  * @updating: %1 if the volume is being updated
  * @changing_leb: %1 if the atomic LEB change ioctl command is in progress
+ * @direct_writes: %1 if direct writes are enabled for this volume
  *
  * @gluebi_desc: gluebi UBI volume descriptor
  * @gluebi_refcount: reference count of the gluebi MTD device
@@ -253,6 +254,7 @@
 	unsigned int upd_marker:1;
 	unsigned int updating:1;
 	unsigned int changing_leb:1;
+	unsigned int direct_writes:1;
  
 #ifdef CONFIG_MTD_UBI_GLUEBI
 	/*
@@ -304,7 +306,8 @@
  * @vtbl_size: size of the volume table in bytes
  * @vtbl: in-RAM volume table copy
  * @volumes_mutex: protects on-flash volume table and serializes volume
- *                 changes, like creation, deletion, update, re-size and re-name
+ *                 changes, like creation, deletion, update, re-size,
+ *                 re-name and set property
  *
  * @max_ec: current highest erase counter value
  * @mean_ec: current mean erase counter value
@@ -124,6 +124,14 @@
  * To check if a logical eraseblock is mapped to a physical eraseblock, the
  * %UBI_IOCEBISMAP ioctl command should be used. It returns %0 if the LEB is
  * not mapped, and %1 if it is mapped.
+ *
+ * Set an UBI volume property
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * To set an UBI volume property the %UBI_IOCSETPROP ioctl command should be
+ * used. A pointer to a &struct ubi_set_prop_req object is expected to be
+ * passed. The object describes which property should be set, and to which value
+ * it should be set.
  */
  
 /*
@@ -175,6 +183,8 @@
 #define UBI_IOCEBUNMAP _IOW(UBI_VOL_IOC_MAGIC, 4, int32_t)
 /* Check if LEB is mapped command */
 #define UBI_IOCEBISMAP _IOR(UBI_VOL_IOC_MAGIC, 5, int32_t)
+/* Set an UBI volume property */
+#define UBI_IOCSETPROP _IOW(UBI_VOL_IOC_MAGIC, 6, struct ubi_set_prop_req)
  
 /* Maximum MTD device name length supported by UBI */
 #define MAX_UBI_MTD_NAME_LEN 127
@@ -210,6 +220,16 @@
 	UBI_STATIC_VOLUME  = 4,
 };
  
+/*
+ * UBI set property ioctl constants
+ *
+ * @UBI_PROP_DIRECT_WRITE: allow / disallow user to directly write and
+ *                         erase individual eraseblocks on dynamic volumes
+ */
+enum {
+       UBI_PROP_DIRECT_WRITE = 1,
+};
+
 /**
  * struct ubi_attach_req - attach MTD device request.
  * @ubi_num: UBI device number to create
@@ -372,6 +392,20 @@
 	int8_t  dtype;
 	int8_t  padding[3];
 } __attribute__ ((packed));
+
+
+/**
+ * struct ubi_set_prop_req - a data structure used to set an ubi volume
+ *                           property.
+ * @property: property to set (%UBI_PROP_DIRECT_WRITE)
+ * @padding: reserved for future, not used, has to be zeroed
+ * @value: value to set
+ */
+struct ubi_set_prop_req {
+       uint8_t  property;
+       uint8_t  padding[7];
+       uint64_t value;
+}  __attribute__ ((packed));
  
 #endif /* __UBI_USER_H__ */
...	...	@@ -33,16 +33,6 @@
33	33	This option switches the background thread off by default. The thread
34	34	may be also be enabled/disabled via UBI sysfs.
35	35
36		-config MTD_UBI_DEBUG_USERSPACE_IO
37		- bool "Direct user-space write/erase support"
38		- default n
39		- depends on MTD_UBI_DEBUG
40		- help
41		- By default, users cannot directly write and erase individual
42		- eraseblocks of dynamic volumes, and have to use update operation
43		- instead. This option enables this capability - it is very useful for
44		- debugging and testing.
45		-
46	36	config MTD_UBI_DEBUG_EMULATE_BITFLIPS
47	37	bool "Emulate flash bit-flips"
48	38	depends on MTD_UBI_DEBUG
...	...	@@ -259,12 +259,9 @@
259	259	return err ? err : count_save - count;
260	260	}
261	261
262		-#ifdef CONFIG_MTD_UBI_DEBUG_USERSPACE_IO
263		-
264	262	/*
265	263	* This function allows to directly write to dynamic UBI volumes, without
266		- * issuing the volume update operation. Available only as a debugging feature.
267		- * Very useful for testing UBI.
	264	+ * issuing the volume update operation.
268	265	*/
269	266	static ssize_t vol_cdev_direct_write(struct file file, const char __user buf,
270	267	size_t count, loff_t *offp)
...	...	@@ -276,6 +273,9 @@
276	273	size_t count_save = count;
277	274	char *tbuf;
278	275
	276	+ if (!vol->direct_writes)
	277	+ return -EPERM;
	278	+
279	279	dbg_gen("requested: write %zd bytes to offset %lld of volume %u",
280	280	count, *offp, vol->vol_id);
281	281
...	...	@@ -339,10 +339,6 @@
339	339	return err ? err : count_save - count;
340	340	}
341	341
342		-#else
343		-#define vol_cdev_direct_write(file, buf, count, offp) (-EPERM)
344		-#endif /* CONFIG_MTD_UBI_DEBUG_USERSPACE_IO */
345		-
346	342	static ssize_t vol_cdev_write(struct file file, const char __user buf,
347	343	size_t count, loff_t *offp)
348	344	{
...	...	@@ -549,6 +545,30 @@
549	545	break;
550	546	}
551	547	err = ubi_is_mapped(desc, lnum);
	548	+ break;
	549	+ }
	550	+
	551	+ /* Set volume property command*/
	552	+ case UBI_IOCSETPROP:
	553	+ {
	554	+ struct ubi_set_prop_req req;
	555	+
	556	+ err = copy_from_user(&req, argp,
	557	+ sizeof(struct ubi_set_prop_req));
	558	+ if (err) {
	559	+ err = -EFAULT;
	560	+ break;
	561	+ }
	562	+ switch (req.property) {
	563	+ case UBI_PROP_DIRECT_WRITE:
	564	+ mutex_lock(&ubi->volumes_mutex);
	565	+ desc->vol->direct_writes = !!req.value;
	566	+ mutex_unlock(&ubi->volumes_mutex);
	567	+ break;
	568	+ default:
	569	+ err = -EINVAL;
	570	+ break;
	571	+ }
552	572	break;
553	573	}
554	574
...	...	@@ -206,6 +206,7 @@
206	206	* @upd_marker: %1 if the update marker is set for this volume
207	207	* @updating: %1 if the volume is being updated
208	208	* @changing_leb: %1 if the atomic LEB change ioctl command is in progress
	209	+ * @direct_writes: %1 if direct writes are enabled for this volume
209	210	*
210	211	* @gluebi_desc: gluebi UBI volume descriptor
211	212	* @gluebi_refcount: reference count of the gluebi MTD device
...	...	@@ -253,6 +254,7 @@
253	254	unsigned int upd_marker:1;
254	255	unsigned int updating:1;
255	256	unsigned int changing_leb:1;
	257	+ unsigned int direct_writes:1;
256	258
257	259	#ifdef CONFIG_MTD_UBI_GLUEBI
258	260	/*
...	...	@@ -304,7 +306,8 @@
304	306	* @vtbl_size: size of the volume table in bytes
305	307	* @vtbl: in-RAM volume table copy
306	308	* @volumes_mutex: protects on-flash volume table and serializes volume
307		- * changes, like creation, deletion, update, re-size and re-name
	309	+ * changes, like creation, deletion, update, re-size,
	310	+ * re-name and set property
308	311	*
309	312	* @max_ec: current highest erase counter value
310	313	* @mean_ec: current mean erase counter value
...	...	@@ -124,6 +124,14 @@
124	124	* To check if a logical eraseblock is mapped to a physical eraseblock, the
125	125	* %UBI_IOCEBISMAP ioctl command should be used. It returns %0 if the LEB is
126	126	* not mapped, and %1 if it is mapped.
	127	+ *
	128	+ * Set an UBI volume property
	129	+ * ~~~~~~~~~~~~~~~~~~~~~~~~~
	130	+ *
	131	+ * To set an UBI volume property the %UBI_IOCSETPROP ioctl command should be
	132	+ * used. A pointer to a &struct ubi_set_prop_req object is expected to be
	133	+ * passed. The object describes which property should be set, and to which value
	134	+ * it should be set.
127	135	*/
128	136
129	137	/*
...	...	@@ -175,6 +183,8 @@
175	183	#define UBI_IOCEBUNMAP _IOW(UBI_VOL_IOC_MAGIC, 4, int32_t)
176	184	/* Check if LEB is mapped command */
177	185	#define UBI_IOCEBISMAP _IOR(UBI_VOL_IOC_MAGIC, 5, int32_t)
	186	+/* Set an UBI volume property */
	187	+#define UBI_IOCSETPROP _IOW(UBI_VOL_IOC_MAGIC, 6, struct ubi_set_prop_req)
178	188
179	189	/* Maximum MTD device name length supported by UBI */
180	190	#define MAX_UBI_MTD_NAME_LEN 127
...	...	@@ -210,6 +220,16 @@
210	220	UBI_STATIC_VOLUME = 4,
211	221	};
212	222
	223	+/*
	224	+ * UBI set property ioctl constants
	225	+ *
	226	+ * @UBI_PROP_DIRECT_WRITE: allow / disallow user to directly write and
	227	+ * erase individual eraseblocks on dynamic volumes
	228	+ */
	229	+enum {
	230	+ UBI_PROP_DIRECT_WRITE = 1,
	231	+};
	232	+
213	233	/**
214	234	* struct ubi_attach_req - attach MTD device request.
215	235	* @ubi_num: UBI device number to create
...	...	@@ -372,6 +392,20 @@
372	392	int8_t dtype;
373	393	int8_t padding[3];
374	394	} __attribute__ ((packed));
	395	+
	396	+
	397	+/**
	398	+ * struct ubi_set_prop_req - a data structure used to set an ubi volume
	399	+ * property.
	400	+ * @property: property to set (%UBI_PROP_DIRECT_WRITE)
	401	+ * @padding: reserved for future, not used, has to be zeroed
	402	+ * @value: value to set
	403	+ */
	404	+struct ubi_set_prop_req {
	405	+ uint8_t property;
	406	+ uint8_t padding[7];
	407	+ uint64_t value;
	408	+} __attribute__ ((packed));
375	409
376	410	#endif /* __UBI_USER_H__ */