Patchwork [7/8] UBI: add ioctl for max_beb_per1024

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Submitter Richard Genoud
Date Aug. 17, 2012, 2:35 p.m.
Message ID <1345214124-5478-8-git-send-email-richard.genoud@gmail.com>
Download mbox | patch
Permalink /patch/178228/
State New
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Comments

Richard Genoud - Aug. 17, 2012, 2:35 p.m.
This patch provides the possibility to adjust the "maximum expected number of
bad blocks per 1024 blocks" (max_beb_per1024) for each mtd device from
UBI_IOCATT ioctl.

The majority of NAND devices have their max_beb_per1024 equal to 20, but
sometimes it's more.
We already could adjust that via a kernel parameter, now we can also use
UBI_IOCATT ioctl:
struct ubi_attach_req {
	__s32 ubi_num;
	__s32 mtd_num;
	__s32 vid_hdr_offset;
	__u8 max_beb_per1024;
	__s8 padding[11];
};

Signed-off-by: Richard Genoud <richard.genoud@gmail.com>
---
 drivers/mtd/ubi/Kconfig |    3 ++-
 drivers/mtd/ubi/cdev.c  |    2 +-
 include/mtd/ubi-user.h  |   19 ++++++++++++++++++-
 3 files changed, 21 insertions(+), 3 deletions(-)
Richard Genoud - Aug. 20, 2012, 9:05 a.m.
2012/8/17 Richard Genoud <richard.genoud@gmail.com>:
> + * The accepted range is 0-255. If 0 is given, the default kernel config value
> + * CONFIG_MTD_UBI_BEB_LIMIT will be used for compatibility.
>   */
>  struct ubi_attach_req {
>         __s32 ubi_num;
>         __s32 mtd_num;
>         __s32 vid_hdr_offset;
> -       __s8 padding[12];
> +       __u8 max_beb_per1024;
> +       __s8 padding[11];
>  };
>
So if I use __u16 instead of __u8, what should be the upper limit ?
1024 ? (1024 is nonsense, but why not...)

Regards,
Richard
Artem Bityutskiy - Aug. 20, 2012, 9:16 a.m.
On Mon, 2012-08-20 at 11:05 +0200, Richard Genoud wrote:
> 2012/8/17 Richard Genoud <richard.genoud@gmail.com>:
> > + * The accepted range is 0-255. If 0 is given, the default kernel config value
> > + * CONFIG_MTD_UBI_BEB_LIMIT will be used for compatibility.
> >   */
> >  struct ubi_attach_req {
> >         __s32 ubi_num;
> >         __s32 mtd_num;
> >         __s32 vid_hdr_offset;
> > -       __s8 padding[12];
> > +       __u8 max_beb_per1024;
> > +       __s8 padding[11];
> >  };
> >
> So if I use __u16 instead of __u8, what should be the upper limit ?
> 1024 ? (1024 is nonsense, but why not...)

Pick a reasonably large number, e.g., 768.

Patch

diff --git a/drivers/mtd/ubi/Kconfig b/drivers/mtd/ubi/Kconfig
index 8b67bac..56531a7 100644
--- a/drivers/mtd/ubi/Kconfig
+++ b/drivers/mtd/ubi/Kconfig
@@ -51,7 +51,8 @@  config MTD_UBI_BEB_LIMIT
 	  MTD partitions of the same size, UBI will reserve 40 eraseblocks when
 	  attaching a partition.
 
-	  This option can be overridden by the kernel parameter ubi.mtd.
+	  This option can be overridden by the kernel parameter ubi.mtd and the
+	  ioctl UBI_IOCATT.
 
 	  Leave the default value if unsure.
 
diff --git a/drivers/mtd/ubi/cdev.c b/drivers/mtd/ubi/cdev.c
index 619f914..7885dc0 100644
--- a/drivers/mtd/ubi/cdev.c
+++ b/drivers/mtd/ubi/cdev.c
@@ -1011,7 +1011,7 @@  static long ctrl_cdev_ioctl(struct file *file, unsigned int cmd,
 		 */
 		mutex_lock(&ubi_devices_mutex);
 		err = ubi_attach_mtd_dev(mtd, req.ubi_num, req.vid_hdr_offset,
-					 CONFIG_MTD_UBI_BEB_LIMIT);
+					 req.max_beb_per1024);
 		mutex_unlock(&ubi_devices_mutex);
 		if (err < 0)
 			put_mtd_device(mtd);
diff --git a/include/mtd/ubi-user.h b/include/mtd/ubi-user.h
index 8787349..8168d9b 100644
--- a/include/mtd/ubi-user.h
+++ b/include/mtd/ubi-user.h
@@ -222,6 +222,7 @@  enum {
  * @ubi_num: UBI device number to create
  * @mtd_num: MTD device number to attach
  * @vid_hdr_offset: VID header offset (use defaults if %0)
+ * @max_beb_per1024: Maximum expected bad eraseblocks per 1024 eraseblocks
  * @padding: reserved for future, not used, has to be zeroed
  *
  * This data structure is used to specify MTD device UBI has to attach and the
@@ -245,12 +246,28 @@  enum {
  * be 2KiB-64 bytes = 1984. Note, that this position is not even 512-bytes
  * aligned, which is OK, as UBI is clever enough to realize this is 4th
  * sub-page of the first page and add needed padding.
+ *
+ * The @max_beb_per1024 is the maximum bad eraseblocks UBI expects on the ubi
+ * device per 1024 eraseblocks.
+ * This value is often given in an other form in the NAND datasheet (min NVB
+ * i.e. minimal number of valid blocks). The maximum expected bad eraseblocks
+ * per 1024 is then:
+ *   1024 * (1 - MinNVB / MaxNVB)
+ * Which gives 20 for most NAND devices.
+ * This limit is used in order to derive amount of eraseblock UBI reserves for
+ * handling new bad blocks.
+ * If the device has more bad eraseblocks than this limit, UBI does not reserve
+ * any physical eraseblocks for new bad eraseblocks, but attempts to use
+ * available eraseblocks (if any).
+ * The accepted range is 0-255. If 0 is given, the default kernel config value
+ * CONFIG_MTD_UBI_BEB_LIMIT will be used for compatibility.
  */
 struct ubi_attach_req {
 	__s32 ubi_num;
 	__s32 mtd_num;
 	__s32 vid_hdr_offset;
-	__s8 padding[12];
+	__u8 max_beb_per1024;
+	__s8 padding[11];
 };
 
 /**