Patchwork UBI: ioctl instead of CONFIG_MTD_UBI_DEBUG_USERSPACE_IO

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Submitter Sidney Amani
Date Jan. 27, 2009, 9:11 a.m.
Message ID <1233047506-30435-1-git-send-email-seed@uffs.org>
Download mbox | patch
Permalink /patch/20422/
State New
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Comments

Sidney Amani - Jan. 27, 2009, 9:11 a.m.
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>
---
 drivers/mtd/ubi/Kconfig.debug |   10 ----------
 drivers/mtd/ubi/cdev.c        |   33 +++++++++++++++++++++++++++------
 drivers/mtd/ubi/ubi.h         |    5 ++++-
 include/mtd/ubi-user.h        |   34 ++++++++++++++++++++++++++++++++++
 4 files changed, 65 insertions(+), 17 deletions(-)
Artem Bityutskiy - Jan. 27, 2009, 12:59 p.m.
On Tue, 2009-01-27 at 10:11 +0100, Sidney Amani wrote:
> 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>

Pushed to ubi-2.6.git, thank you.
Artem Bityutskiy - Jan. 27, 2009, 1:06 p.m.
On Tue, 2009-01-27 at 10:11 +0100, Sidney Amani wrote:
> 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>

But I have to warn you, that now you are responsible for writing
eraseblocks properly:

1. Sequentially, from the beginning to the end.
2. Writes have to be aligned to min I/O unit size
3. You cannot write more than once to the same place

Be careful.
Corentin Chary - Jan. 27, 2009, 2:18 p.m.
On Tue, Jan 27, 2009 at 2:06 PM, Artem Bityutskiy
<dedekind@infradead.org> wrote:
> On Tue, 2009-01-27 at 10:11 +0100, Sidney Amani wrote:
>> 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>
>
> But I have to warn you, that now you are responsible for writing
> eraseblocks properly:
>
> 1. Sequentially, from the beginning to the end.
> 2. Writes have to be aligned to min I/O unit size
> 3. You cannot write more than once to the same place
>
> Be careful.

We are aware of that =).
We are currently working on a libubi in userspace wich will provide
the same interface the kernel does (and will also do the same checks:
aligned writes, etc ...). It should be finished this week. I'll send a
mail here when it's done.

Thanks.
Artem Bityutskiy - Jan. 30, 2009, 7:40 a.m.
On Tue, 2009-01-27 at 10:11 +0100, Sidney Amani wrote:
> 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>

FYI, this and the other ioctl patches from Corentin went to
Linus's tree today and will show up in 2.6.29. HTH.

Patch

diff --git a/drivers/mtd/ubi/Kconfig.debug b/drivers/mtd/ubi/Kconfig.debug
index 1e2ee22..2246f15 100644
--- a/drivers/mtd/ubi/Kconfig.debug
+++ b/drivers/mtd/ubi/Kconfig.debug
@@ -33,16 +33,6 @@  config MTD_UBI_DEBUG_DISABLE_BGT
 	  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
diff --git a/drivers/mtd/ubi/cdev.c b/drivers/mtd/ubi/cdev.c
index f9631eb..350b744 100644
--- a/drivers/mtd/ubi/cdev.c
+++ b/drivers/mtd/ubi/cdev.c
@@ -259,8 +259,6 @@  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.
@@ -276,6 +274,9 @@  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 +340,6 @@  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 +549,30 @@  static long vol_cdev_ioctl(struct file *file, unsigned int cmd,
 		break;
 	}
 
+	/* UBI ioctl set property */
+	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;
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index 381f0e1..7acedfc 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -206,6 +206,7 @@  struct ubi_volume_desc;
  * @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 write operation are enabled for users
  *
  * @gluebi_desc: gluebi UBI volume descriptor
  * @gluebi_refcount: reference count of the gluebi MTD device
@@ -253,6 +254,7 @@  struct ubi_volume {
 	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 @@  struct ubi_wl_entry;
  * @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
diff --git a/include/mtd/ubi-user.h b/include/mtd/ubi-user.h
index 82113e1..aa2e24b 100644
--- a/include/mtd/ubi-user.h
+++ b/include/mtd/ubi-user.h
@@ -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 ioctl sets the property and the value provided by the &struct
+ * ubi_set_prop_req object.
  */
 
 /*
@@ -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 @@  enum {
 	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
@@ -373,4 +393,18 @@  struct ubi_map_req {
 	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__ */