[PATCH 4/4] UBI: replace MTD_UBI_BEB_LIMIT with user-space parameter

From: Richard Genoud
Date: Tue Jul 10 2012 - 12:24:28 EST

This patch provides the possibility to adjust the "maximum expected number of
bad blocks per 1024 blocks" (max_beb_per1024) for each mtd device.

The majority of NAND devices have their max_beb_per1024 equal to 20, but
sometimes it's more.
Now, we can adjust that via a kernel parameter:
ubi.mtd=<name|num|path>[,<vid_hdr_offs>[,max_beb_per1024]]
and via UBI_IOCATT ioctl which is now:
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@xxxxxxxxx>
---
drivers/mtd/ubi/Kconfig | 25 --------------
drivers/mtd/ubi/build.c | 82 +++++++++++++++++++++++++++++++---------------
drivers/mtd/ubi/cdev.c | 9 ++++-
drivers/mtd/ubi/ubi.h | 6 +++-
include/mtd/ubi-user.h | 19 ++++++++++-
5 files changed, 86 insertions(+), 55 deletions(-)

diff --git a/drivers/mtd/ubi/Kconfig b/drivers/mtd/ubi/Kconfig
index b77ffe1..7a57cc0 100644
--- a/drivers/mtd/ubi/Kconfig
+++ b/drivers/mtd/ubi/Kconfig
@@ -27,31 +27,6 @@ config MTD_UBI_WL_THRESHOLD
life-cycle less than 10000, the threshold should be lessened (e.g.,
to 128 or 256, although it does not have to be power of 2).

-config MTD_UBI_BEB_LIMIT
- int "Maximum expected bad eraseblocks per 1024 eraseblocks"
- default 20
- range 2 256
- help
- If the MTD device admits of bad eraseblocks (e.g. NAND flash), UBI
- reserves some amount of physical eraseblocks to handle new bad
- eraseblocks.
- This option specifies 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).
- If the underlying flash does not admit of bad eraseblocks (e.g. NOR
- flash), this value is ignored.
- Leave the default value if unsure.
-
config MTD_UBI_GLUEBI
tristate "MTD devices emulation driver (gluebi)"
help
diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index 87b39c2..76358e9 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -46,6 +46,8 @@
/* Maximum length of the 'mtd=' parameter */
#define MTD_PARAM_LEN_MAX 64

+#define MTD_PARAM_NB_MAX 3
+
#ifdef CONFIG_MTD_UBI_MODULE
#define ubi_is_module() 1
#else
@@ -57,10 +59,12 @@
* @name: MTD character device node path, MTD device name, or MTD device number
* string
* @vid_hdr_offs: VID header offset
+ * @max_beb_per1024: maximum expected number of bad blocks per 1024 erase blocks
*/
struct mtd_dev_param {
char name[MTD_PARAM_LEN_MAX];
int vid_hdr_offs;
+ int max_beb_per1024;
};

/* Numbers of elements set in the @mtd_dev_param array */
@@ -565,9 +569,37 @@ void ubi_free_internal_volumes(struct ubi_device *ubi)
}
}

+static int get_bad_peb_limit(const struct ubi_device *ubi, int max_beb_per1024)
+{
+ int device_peb_count;
+ uint64_t device_size;
+ int beb_limit = 0;
+
+ /* this has already been checked in ioctl */
+ if (max_beb_per1024 <= 0)
+ goto out;
+
+ /* we are using here the whole MTD device size and not
+ * the MTD partition size because the maximum number of
+ * bad blocks is a percentage of the whole device and
+ * the bad blocks are not fairly disposed on a flash
+ * device
+ */
+ device_size = mtd_get_device_size(ubi->mtd);
+ device_peb_count = mtd_div_by_eb(device_size, ubi->mtd);
+ beb_limit = mult_frac(device_peb_count, max_beb_per1024, 1024);
+ /* round it up */
+ if (mult_frac(beb_limit, 1024, max_beb_per1024) < ubi->peb_count)
+ beb_limit++;
+
+out:
+ return beb_limit;
+}
+
/**
* io_init - initialize I/O sub-system for a given UBI device.
* @ubi: UBI device description object
+ * @max_beb_per1024: maximum expected number of bad PEB per 1024 PEB
*
* If @ubi->vid_hdr_offset or @ubi->leb_start is zero, default offsets are
* assumed:
@@ -580,7 +612,7 @@ void ubi_free_internal_volumes(struct ubi_device *ubi)
* This function returns zero in case of success and a negative error code in
* case of failure.
*/
-static int io_init(struct ubi_device *ubi)
+static int io_init(struct ubi_device *ubi, int max_beb_per1024)
{
if (ubi->mtd->numeraseregions != 0) {
/*
@@ -610,26 +642,7 @@ static int io_init(struct ubi_device *ubi)

if (mtd_can_have_bb(ubi->mtd)) {
ubi->bad_allowed = 1;
- if (CONFIG_MTD_UBI_BEB_LIMIT > 0) {
- int per1024 = CONFIG_MTD_UBI_BEB_LIMIT;
- int device_peb_count;
- uint64_t device_size;
- int beb_limit;
-
- /* we are using here the whole MTD device size and not
- * the MTD partition size because the maximum number of
- * bad blocks is a percentage of the whole device and
- * the bad blocks are not fairly disposed on a flash
- * device
- */
- device_size = mtd_get_device_size(ubi->mtd);
- device_peb_count = mtd_div_by_eb(device_size, ubi->mtd);
- beb_limit = mult_frac(device_peb_count, per1024, 1024);
- /* round it up */
- if (mult_frac(beb_limit, 1024, per1024) < ubi->peb_count)
- beb_limit++;
- ubi->bad_peb_limit = beb_limit;
- }
+ ubi->bad_peb_limit = get_bad_peb_limit(ubi, max_beb_per1024);
}

if (ubi->mtd->type == MTD_NORFLASH) {
@@ -822,6 +835,7 @@ static int autoresize(struct ubi_device *ubi, int vol_id)
* @mtd: MTD device description object
* @ubi_num: number to assign to the new UBI device
* @vid_hdr_offset: VID header offset
+ * @max_beb_per1024: maximum number of expected bad blocks per 1024 eraseblocks
*
* This function attaches MTD device @mtd_dev to UBI and assign @ubi_num number
* to the newly created UBI device, unless @ubi_num is %UBI_DEV_NUM_AUTO, in
@@ -832,7 +846,8 @@ static int autoresize(struct ubi_device *ubi, int vol_id)
* Note, the invocations of this function has to be serialized by the
* @ubi_devices_mutex.
*/
-int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset)
+int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,
+ int vid_hdr_offset, int max_beb_per1024)
{
struct ubi_device *ubi;
int i, err, ref = 0;
@@ -905,7 +920,7 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset)
dbg_msg("sizeof(struct ubi_ainf_peb) %zu", sizeof(struct ubi_ainf_peb));
dbg_msg("sizeof(struct ubi_wl_entry) %zu", sizeof(struct ubi_wl_entry));

- err = io_init(ubi);
+ err = io_init(ubi, max_beb_per1024);
if (err)
goto out_free;

@@ -1194,7 +1209,7 @@ static int __init ubi_init(void)

mutex_lock(&ubi_devices_mutex);
err = ubi_attach_mtd_dev(mtd, UBI_DEV_NUM_AUTO,
- p->vid_hdr_offs);
+ p->vid_hdr_offs, p->max_beb_per1024);
mutex_unlock(&ubi_devices_mutex);
if (err < 0) {
ubi_err("cannot attach mtd%d", mtd->index);
@@ -1313,7 +1328,7 @@ static int __init ubi_mtd_param_parse(const char *val, struct kernel_param *kp)
struct mtd_dev_param *p;
char buf[MTD_PARAM_LEN_MAX];
char *pbuf = &buf[0];
- char *tokens[2] = {NULL, NULL};
+ char *tokens[MTD_PARAM_NB_MAX];

if (!val)
return -EINVAL;
@@ -1343,7 +1358,7 @@ static int __init ubi_mtd_param_parse(const char *val, struct kernel_param *kp)
if (buf[len - 1] == '\n')
buf[len - 1] = '\0';

- for (i = 0; i < 2; i++)
+ for (i = 0; i < MTD_PARAM_NB_MAX; i++)
tokens[i] = strsep(&pbuf, ",");

if (pbuf) {
@@ -1361,18 +1376,31 @@ static int __init ubi_mtd_param_parse(const char *val, struct kernel_param *kp)
if (p->vid_hdr_offs < 0)
return p->vid_hdr_offs;

+ if (tokens[2])
+ p->max_beb_per1024 = bytes_str_to_int(tokens[2]);
+ /* a value of 0 is force to the default value to keep the same
+ * behavior between ubiattach command and module parameter
+ */
+ if (!p->max_beb_per1024)
+ p->max_beb_per1024 = MTD_UBI_DEFAULT_BEB_LIMIT;
+
mtd_devs += 1;
return 0;
}

module_param_call(mtd, ubi_mtd_param_parse, NULL, NULL, 000);
MODULE_PARM_DESC(mtd, "MTD devices to attach. Parameter format: "
- "mtd=<name|num|path>[,<vid_hdr_offs>].\n"
+ "mtd=<name|num|path>[,<vid_hdr_offs>[,"
+ "max_beb_per1024]].\n"
"Multiple \"mtd\" parameters may be specified.\n"
"MTD devices may be specified by their number, name, or "
"path to the MTD character device node.\n"
"Optional \"vid_hdr_offs\" parameter specifies UBI VID "
"header position to be used by UBI.\n"
+ "Optional \"max_beb_per1024\" parameter specifies the "
+ "maximum expected bad eraseblock per 1024 eraseblocks."
+ "(default " __stringify(MTD_UBI_DEFAULT_BEB_LIMIT)
+ " if 0 or not set)\n"
"Example 1: mtd=/dev/mtd0 - attach MTD device "
"/dev/mtd0.\n"
"Example 2: mtd=content,1984 mtd=4 - attach MTD device "
diff --git a/drivers/mtd/ubi/cdev.c b/drivers/mtd/ubi/cdev.c
index acec85d..ed5dd75 100644
--- a/drivers/mtd/ubi/cdev.c
+++ b/drivers/mtd/ubi/cdev.c
@@ -1005,12 +1005,19 @@ static long ctrl_cdev_ioctl(struct file *file, unsigned int cmd,
break;
}

+ /* for compatibility with older user-space tools,
+ * a zero value should be treated like a default value
+ */
+ if (!req.max_beb_per1024)
+ req.max_beb_per1024 = MTD_UBI_DEFAULT_BEB_LIMIT;
+
/*
* Note, further request verification is done by
* 'ubi_attach_mtd_dev()'.
*/
mutex_lock(&ubi_devices_mutex);
- err = ubi_attach_mtd_dev(mtd, req.ubi_num, req.vid_hdr_offset);
+ err = ubi_attach_mtd_dev(mtd, req.ubi_num, req.vid_hdr_offset,
+ req.max_beb_per1024);
mutex_unlock(&ubi_devices_mutex);
if (err < 0)
put_mtd_device(mtd);
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index c94612e..2148f35 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -50,6 +50,9 @@
/* UBI name used for character devices, sysfs, etc */
#define UBI_NAME_STR "ubi"

+/* Default number of maximum expected bad blocks per 1024 eraseblocks */
+#define MTD_UBI_DEFAULT_BEB_LIMIT 20
+
/* Normal UBI messages */
#define ubi_msg(fmt, ...) printk(KERN_NOTICE "UBI: " fmt "\n", ##__VA_ARGS__)
/* UBI warning messages */
@@ -693,7 +696,8 @@ int ubi_io_write_vid_hdr(struct ubi_device *ubi, int pnum,
struct ubi_vid_hdr *vid_hdr);

/* build.c */
-int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset);
+int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,
+ int vid_hdr_offset, int max_beb_per1024);
int ubi_detach_mtd_dev(int ubi_num, int anyway);
struct ubi_device *ubi_get_device(int ubi_num);
void ubi_put_device(struct ubi_device *ubi);
diff --git a/include/mtd/ubi-user.h b/include/mtd/ubi-user.h
index 8787349..77cd0d1 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 value
+ * MTD_UBI_DEFAULT_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];
};

/**
--
1.7.2.5

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