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UBI: add UBI devices reference counting

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This is one more step on the way to "removable" UBI devices. It
adds reference counting for UBI devices. Every time a volume on
this device is opened - the device's refcount is increased. It
is also increased if someone is reading any sysfs file of this
UBI device or of one of its volumes.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
This commit is contained in:
Artem Bityutskiy 2007-12-17 17:37:26 +02:00
parent 9f961b5756
commit e73f4459d9
7 changed files with 201 additions and 63 deletions
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142
drivers/mtd/ubi/build.c
View File

@ -64,9 +64,6 @@ static int mtd_devs = 0;
/* MTD devices specification parameters */
static struct mtd_dev_param mtd_dev_param[UBI_MAX_DEVICES];
/* All UBI devices in system */
struct ubi_device *ubi_devices[UBI_MAX_DEVICES];
/* Root UBI "class" object (corresponds to '/<sysfs>/class/ubi/') */
struct class *ubi_class;
@ -83,6 +80,12 @@ static struct miscdevice ubi_ctrl_cdev = {
.fops = &ubi_ctrl_cdev_operations,
};
/* All UBI devices in system */
static struct ubi_device *ubi_devices[UBI_MAX_DEVICES];
/* Protects @ubi_devices and @ubi->ref_count */
static DEFINE_SPINLOCK(ubi_devices_lock);
/* "Show" method for files in '/<sysfs>/class/ubi/' */
static ssize_t ubi_version_show(struct class *class, char *buf)
{
@ -118,37 +121,145 @@ static struct device_attribute dev_min_io_size =
static struct device_attribute dev_bgt_enabled =
__ATTR(bgt_enabled, S_IRUGO, dev_attribute_show, NULL);
/**
* ubi_get_device - get UBI device.
* @ubi_num: UBI device number
*
* This function returns UBI device description object for UBI device number
* @ubi_num, or %NULL if the device does not exist. This function increases the
* device reference count to prevent removal of the device. In other words, the
* device cannot be removed if its reference count is not zero.
*/
struct ubi_device *ubi_get_device(int ubi_num)
{
struct ubi_device *ubi;
spin_lock(&ubi_devices_lock);
ubi = ubi_devices[ubi_num];
if (ubi) {
ubi_assert(ubi->ref_count >= 0);
ubi->ref_count += 1;
get_device(&ubi->dev);
}
spin_unlock(&ubi_devices_lock);
return ubi;
}
/**
* ubi_put_device - drop an UBI device reference.
* @ubi: UBI device description object
*/
void ubi_put_device(struct ubi_device *ubi)
{
spin_lock(&ubi_devices_lock);
ubi->ref_count -= 1;
put_device(&ubi->dev);
spin_unlock(&ubi_devices_lock);
}
/**
* ubi_get_by_major - get UBI device description object by character device
* major number.
* @major: major number
*
* This function is similar to 'ubi_get_device()', but it searches the device
* by its major number.
*/
struct ubi_device *ubi_get_by_major(int major)
{
int i;
struct ubi_device *ubi;
spin_lock(&ubi_devices_lock);
for (i = 0; i < UBI_MAX_DEVICES; i++) {
ubi = ubi_devices[i];
if (ubi && MAJOR(ubi->cdev.dev) == major) {
ubi_assert(ubi->ref_count >= 0);
ubi->ref_count += 1;
get_device(&ubi->dev);
spin_unlock(&ubi_devices_lock);
return ubi;
}
}
spin_unlock(&ubi_devices_lock);
return NULL;
}
/**
* ubi_major2num - get UBI device number by character device major number.
* @major: major number
*
* This function searches UBI device number object by its major number. If UBI
* device was not found, this function returns -ENODEV, othewise the UBI device
* number is returned.
*/
int ubi_major2num(int major)
{
int i, ubi_num = -ENODEV;
spin_lock(&ubi_devices_lock);
for (i = 0; i < UBI_MAX_DEVICES; i++) {
struct ubi_device *ubi = ubi_devices[i];
if (ubi && MAJOR(ubi->cdev.dev) == major) {
ubi_num = ubi->ubi_num;
break;
}
}
spin_unlock(&ubi_devices_lock);
return ubi_num;
}
/* "Show" method for files in '/<sysfs>/class/ubi/ubiX/' */
static ssize_t dev_attribute_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
const struct ubi_device *ubi;
ssize_t ret;
struct ubi_device *ubi;
/*
* The below code looks weird, but it actually makes sense. We get the
* UBI device reference from the contained 'struct ubi_device'. But it
* is unclear if the device was removed or not yet. Indeed, if the
* device was removed before we increased its reference count,
* 'ubi_get_device()' will return -ENODEV and we fail.
*
* Remember, 'struct ubi_device' is freed in the release function, so
* we still can use 'ubi->ubi_num'.
*/
ubi = container_of(dev, struct ubi_device, dev);
ubi = ubi_get_device(ubi->ubi_num);
if (!ubi)
return -ENODEV;
if (attr == &dev_eraseblock_size)
return sprintf(buf, "%d\n", ubi->leb_size);
ret = sprintf(buf, "%d\n", ubi->leb_size);
else if (attr == &dev_avail_eraseblocks)
return sprintf(buf, "%d\n", ubi->avail_pebs);
ret = sprintf(buf, "%d\n", ubi->avail_pebs);
else if (attr == &dev_total_eraseblocks)
return sprintf(buf, "%d\n", ubi->good_peb_count);
ret = sprintf(buf, "%d\n", ubi->good_peb_count);
else if (attr == &dev_volumes_count)
return sprintf(buf, "%d\n", ubi->vol_count);
ret = sprintf(buf, "%d\n", ubi->vol_count);
else if (attr == &dev_max_ec)
return sprintf(buf, "%d\n", ubi->max_ec);
ret = sprintf(buf, "%d\n", ubi->max_ec);
else if (attr == &dev_reserved_for_bad)
return sprintf(buf, "%d\n", ubi->beb_rsvd_pebs);
ret = sprintf(buf, "%d\n", ubi->beb_rsvd_pebs);
else if (attr == &dev_bad_peb_count)
return sprintf(buf, "%d\n", ubi->bad_peb_count);
ret = sprintf(buf, "%d\n", ubi->bad_peb_count);
else if (attr == &dev_max_vol_count)
return sprintf(buf, "%d\n", ubi->vtbl_slots);
ret = sprintf(buf, "%d\n", ubi->vtbl_slots);
else if (attr == &dev_min_io_size)
return sprintf(buf, "%d\n", ubi->min_io_size);
ret = sprintf(buf, "%d\n", ubi->min_io_size);
else if (attr == &dev_bgt_enabled)
return sprintf(buf, "%d\n", ubi->thread_enabled);
ret = sprintf(buf, "%d\n", ubi->thread_enabled);
else
BUG();
return 0;
ubi_put_device(ubi);
return ret;
}
/* Fake "release" method for UBI devices */
@ -670,6 +781,7 @@ static void detach_mtd_dev(struct ubi_device *ubi)
int ubi_num = ubi->ubi_num, mtd_num = ubi->mtd->index;
dbg_msg("detaching mtd%d from ubi%d", ubi->mtd->index, ubi_num);
ubi_assert(ubi->ref_count == 0);
uif_close(ubi);
ubi_eba_close(ubi);
ubi_wl_close(ubi);

34
drivers/mtd/ubi/cdev.c
View File

@ -55,23 +55,6 @@
#define VOL_CDEV_IOC_MAX_SEQ 2
#endif
/**
* major_to_device - get UBI device object by character device major number.
* @major: major number
*
* This function returns a pointer to the UBI device object.
*/
static struct ubi_device *major_to_device(int major)
{
int i;
for (i = 0; i < UBI_MAX_DEVICES; i++)
if (ubi_devices[i] && MAJOR(ubi_devices[i]->cdev.dev) == major)
return ubi_devices[i];
BUG();
return NULL;
}
/**
* get_exclusive - get exclusive access to an UBI volume.
* @desc: volume descriptor
@ -129,9 +112,11 @@ static void revoke_exclusive(struct ubi_volume_desc *desc, int mode)
static int vol_cdev_open(struct inode *inode, struct file *file)
{
struct ubi_volume_desc *desc;
const struct ubi_device *ubi = major_to_device(imajor(inode));
int vol_id = iminor(inode) - 1;
int mode;
int vol_id = iminor(inode) - 1, mode, ubi_num;
ubi_num = ubi_major2num(imajor(inode));
if (ubi_num < 0)
return ubi_num;
if (file->f_mode & FMODE_WRITE)
mode = UBI_READWRITE;
@ -140,7 +125,7 @@ static int vol_cdev_open(struct inode *inode, struct file *file)
dbg_msg("open volume %d, mode %d", vol_id, mode);
desc = ubi_open_volume(ubi->ubi_num, vol_id, mode);
desc = ubi_open_volume(ubi_num, vol_id, mode);
if (IS_ERR(desc))
return PTR_ERR(desc);
@ -586,9 +571,9 @@ static int ubi_cdev_ioctl(struct inode *inode, struct file *file,
if (!capable(CAP_SYS_RESOURCE))
return -EPERM;
ubi = major_to_device(imajor(inode));
if (IS_ERR(ubi))
return PTR_ERR(ubi);
ubi = ubi_get_by_major(imajor(inode));
if (!ubi)
return -ENODEV;
switch (cmd) {
/* Create volume command */
@ -695,6 +680,7 @@ static int ubi_cdev_ioctl(struct inode *inode, struct file *file,
break;
}
ubi_put_device(ubi);
return err;
}

5
drivers/mtd/ubi/eba.c
View File

@ -339,6 +339,7 @@ int ubi_eba_unmap_leb(struct ubi_device *ubi, struct ubi_volume *vol,
{
int err, pnum, vol_id = vol->vol_id;
ubi_assert(ubi->ref_count > 0);
ubi_assert(vol->ref_count > 0);
if (ubi->ro_mode)
@ -389,6 +390,7 @@ int ubi_eba_read_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
struct ubi_vid_hdr *vid_hdr;
uint32_t uninitialized_var(crc);
ubi_assert(ubi->ref_count > 0);
ubi_assert(vol->ref_count > 0);
err = leb_read_lock(ubi, vol_id, lnum);
@ -614,6 +616,7 @@ int ubi_eba_write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
int err, pnum, tries = 0, vol_id = vol->vol_id;
struct ubi_vid_hdr *vid_hdr;
ubi_assert(ubi->ref_count > 0);
ubi_assert(vol->ref_count > 0);
if (ubi->ro_mode)
@ -749,6 +752,7 @@ int ubi_eba_write_leb_st(struct ubi_device *ubi, struct ubi_volume *vol,
struct ubi_vid_hdr *vid_hdr;
uint32_t crc;
ubi_assert(ubi->ref_count > 0);
ubi_assert(vol->ref_count > 0);
if (ubi->ro_mode)
@ -865,6 +869,7 @@ int ubi_eba_atomic_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
struct ubi_vid_hdr *vid_hdr;
uint32_t crc;
ubi_assert(ubi->ref_count > 0);
ubi_assert(vol->ref_count > 0);
if (ubi->ro_mode)

59
drivers/mtd/ubi/kapi.c
View File

@ -30,23 +30,27 @@
* @ubi_num: UBI device number
* @di: the information is stored here
*
* This function returns %0 in case of success and a %-ENODEV if there is no
* such UBI device.
* This function returns %0 in case of success, %-EINVAL if the UBI device
* number is invalid, and %-ENODEV if there is no such UBI device.
*/
int ubi_get_device_info(int ubi_num, struct ubi_device_info *di)
{
const struct ubi_device *ubi;
struct ubi_device *ubi;
if (ubi_num < 0 || ubi_num >= UBI_MAX_DEVICES ||
!ubi_devices[ubi_num])
if (ubi_num < 0 || ubi_num >= UBI_MAX_DEVICES)
return -EINVAL;
ubi = ubi_get_device(ubi_num);
if (!ubi)
return -ENODEV;
ubi = ubi_devices[ubi_num];
di->ubi_num = ubi->ubi_num;
di->leb_size = ubi->leb_size;
di->min_io_size = ubi->min_io_size;
di->ro_mode = ubi->ro_mode;
di->cdev = ubi->cdev.dev;
ubi_put_device(ubi);
return 0;
}
EXPORT_SYMBOL_GPL(ubi_get_device_info);
@ -111,16 +115,23 @@ struct ubi_volume_desc *ubi_open_volume(int ubi_num, int vol_id, int mode)
mode != UBI_EXCLUSIVE)
return ERR_PTR(-EINVAL);
ubi = ubi_devices[ubi_num];
/*
* First of all, we have to get the UBI device to prevent its removal.
*/
ubi = ubi_get_device(ubi_num);
if (!ubi)
return ERR_PTR(-ENODEV);
if (vol_id < 0 || vol_id >= ubi->vtbl_slots)
return ERR_PTR(-EINVAL);
if (vol_id < 0 || vol_id >= ubi->vtbl_slots) {
err = -EINVAL;
goto out_put_ubi;
}
desc = kmalloc(sizeof(struct ubi_volume_desc), GFP_KERNEL);
if (!desc)
return ERR_PTR(-ENOMEM);
if (!desc) {
err = -ENOMEM;
goto out_put_ubi;
}
err = -ENODEV;
if (!try_module_get(THIS_MODULE))
@ -188,6 +199,8 @@ out_unlock:
module_put(THIS_MODULE);
out_free:
kfree(desc);
out_put_ubi:
ubi_put_device(ubi);
return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(ubi_open_volume);
@ -205,6 +218,7 @@ struct ubi_volume_desc *ubi_open_volume_nm(int ubi_num, const char *name,
{
int i, vol_id = -1, len;
struct ubi_device *ubi;
struct ubi_volume_desc *ret;
dbg_msg("open volume %s, mode %d", name, mode);
@ -218,7 +232,7 @@ struct ubi_volume_desc *ubi_open_volume_nm(int ubi_num, const char *name,
if (ubi_num < 0 || ubi_num >= UBI_MAX_DEVICES)
return ERR_PTR(-EINVAL);
ubi = ubi_devices[ubi_num];
ubi = ubi_get_device(ubi_num);
if (!ubi)
return ERR_PTR(-ENODEV);
@ -234,10 +248,17 @@ struct ubi_volume_desc *ubi_open_volume_nm(int ubi_num, const char *name,
}
spin_unlock(&ubi->volumes_lock);
if (vol_id < 0)
return ERR_PTR(-ENODEV);
if (vol_id >= 0)
ret = ubi_open_volume(ubi_num, vol_id, mode);
else
ret = ERR_PTR(-ENODEV);
return ubi_open_volume(ubi_num, vol_id, mode);
/*
* We should put the UBI device even in case of success, because
* 'ubi_open_volume()' took a reference as well.
*/
ubi_put_device(ubi);
return ret;
}
EXPORT_SYMBOL_GPL(ubi_open_volume_nm);
@ -248,10 +269,11 @@ EXPORT_SYMBOL_GPL(ubi_open_volume_nm);
void ubi_close_volume(struct ubi_volume_desc *desc)
{
struct ubi_volume *vol = desc->vol;
struct ubi_device *ubi = vol->ubi;
dbg_msg("close volume %d, mode %d", vol->vol_id, desc->mode);
spin_lock(&vol->ubi->volumes_lock);
spin_lock(&ubi->volumes_lock);
switch (desc->mode) {
case UBI_READONLY:
vol->readers -= 1;
@ -263,10 +285,11 @@ void ubi_close_volume(struct ubi_volume_desc *desc)
vol->exclusive = 0;
}
vol->ref_count -= 1;
spin_unlock(&vol->ubi->volumes_lock);
spin_unlock(&ubi->volumes_lock);
put_device(&vol->dev);
kfree(desc);
put_device(&vol->dev);
ubi_put_device(ubi);
module_put(THIS_MODULE);
}
EXPORT_SYMBOL_GPL(ubi_close_volume);

9
drivers/mtd/ubi/ubi.h
View File

@ -245,6 +245,7 @@ struct ubi_wl_entry;
* @beb_rsvd_level, @bad_peb_count, @good_peb_count, @vol_count,
* @vol->readers, @vol->writers, @vol->exclusive,
* @vol->ref_count, @vol->mapping and @vol->eba_tbl.
* @ref_count: count of references on the UBI device
*
* @rsvd_pebs: count of reserved physical eraseblocks
* @avail_pebs: count of available physical eraseblocks
@ -325,6 +326,7 @@ struct ubi_device {
int vol_count;
struct ubi_volume *volumes[UBI_MAX_VOLUMES+UBI_INT_VOL_COUNT];
spinlock_t volumes_lock;
int ref_count;
int rsvd_pebs;
int avail_pebs;
@ -401,7 +403,6 @@ extern struct kmem_cache *ubi_wl_entry_slab;
extern struct file_operations ubi_ctrl_cdev_operations;
extern struct file_operations ubi_cdev_operations;
extern struct file_operations ubi_vol_cdev_operations;
extern struct ubi_device *ubi_devices[];
extern struct class *ubi_class;
/* vtbl.c */
@ -479,6 +480,12 @@ int ubi_io_read_vid_hdr(struct ubi_device *ubi, int pnum,
int ubi_io_write_vid_hdr(struct ubi_device *ubi, int pnum,
struct ubi_vid_hdr *vid_hdr);
/* build.c */
struct ubi_device *ubi_get_device(int ubi_num);
void ubi_put_device(struct ubi_device *ubi);
struct ubi_device *ubi_get_by_major(int major);
int ubi_major2num(int major);
/*
* ubi_rb_for_each_entry - walk an RB-tree.
* @rb: a pointer to type 'struct rb_node' to to use as a loop counter

14
drivers/mtd/ubi/vmt.c
View File

@ -71,11 +71,16 @@ static ssize_t vol_attribute_show(struct device *dev,
{
int ret;
struct ubi_volume *vol = container_of(dev, struct ubi_volume, dev);
struct ubi_device *ubi = vol->ubi;
struct ubi_device *ubi;
ubi = ubi_get_device(vol->ubi->ubi_num);
if (!ubi)
return -ENODEV;
spin_lock(&ubi->volumes_lock);
if (!ubi->volumes[vol->vol_id]) {
spin_unlock(&ubi->volumes_lock);
ubi_put_device(ubi);
return -ENODEV;
}
/* Take a reference to prevent volume removal */
@ -108,10 +113,12 @@ static ssize_t vol_attribute_show(struct device *dev,
/* This must be a bug */
ret = -EINVAL;
/* We've done the operation, drop volume and UBI device references */
spin_lock(&ubi->volumes_lock);
vol->ref_count -= 1;
ubi_assert(vol->ref_count >= 0);
spin_unlock(&ubi->volumes_lock);
ubi_put_device(ubi);
return ret;
}
@ -260,6 +267,7 @@ int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req)
}
ubi->avail_pebs -= vol->reserved_pebs;
ubi->rsvd_pebs += vol->reserved_pebs;
spin_unlock(&ubi->volumes_lock);
vol->vol_id = vol_id;
vol->alignment = req->alignment;
@ -267,9 +275,7 @@ int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req)
vol->vol_type = req->vol_type;
vol->name_len = req->name_len;
memcpy(vol->name, req->name, vol->name_len + 1);
vol->exclusive = 1;
vol->ubi = ubi;
spin_unlock(&ubi->volumes_lock);
/*
* Finish all pending erases because there may be some LEBs belonging
@ -350,8 +356,6 @@ int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req)
goto out_sysfs;
spin_lock(&ubi->volumes_lock);
ubi->vol_count += 1;
vol->exclusive = 0;
ubi->volumes[vol_id] = vol;
spin_unlock(&ubi->volumes_lock);

1
drivers/mtd/ubi/wl.c
View File

@ -1303,6 +1303,7 @@ int ubi_wl_flush(struct ubi_device *ubi)
* Make sure all the works which have been done in parallel are
* finished.
*/
ubi_assert(ubi->ref_count > 0);
down_write(&ubi->work_sem);
up_write(&ubi->work_sem);