diff --git a/drivers/block/loop.c b/drivers/block/loop.c index f3c636d237187df21879c0e8acc4a4c943e59ad2..dc552308668ec40abbd2ee370ee4e66f98ccc693 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -74,6 +74,7 @@ #include #include #include +#include #include @@ -737,6 +738,103 @@ static inline int is_loop_device(struct file *file) return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR; } +/* loop sysfs attributes */ + +static ssize_t loop_attr_show(struct device *dev, char *page, + ssize_t (*callback)(struct loop_device *, char *)) +{ + struct loop_device *l, *lo = NULL; + + mutex_lock(&loop_devices_mutex); + list_for_each_entry(l, &loop_devices, lo_list) + if (disk_to_dev(l->lo_disk) == dev) { + lo = l; + break; + } + mutex_unlock(&loop_devices_mutex); + + return lo ? callback(lo, page) : -EIO; +} + +#define LOOP_ATTR_RO(_name) \ +static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \ +static ssize_t loop_attr_do_show_##_name(struct device *d, \ + struct device_attribute *attr, char *b) \ +{ \ + return loop_attr_show(d, b, loop_attr_##_name##_show); \ +} \ +static struct device_attribute loop_attr_##_name = \ + __ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL); + +static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf) +{ + ssize_t ret; + char *p = NULL; + + mutex_lock(&lo->lo_ctl_mutex); + if (lo->lo_backing_file) + p = d_path(&lo->lo_backing_file->f_path, buf, PAGE_SIZE - 1); + mutex_unlock(&lo->lo_ctl_mutex); + + if (IS_ERR_OR_NULL(p)) + ret = PTR_ERR(p); + else { + ret = strlen(p); + memmove(buf, p, ret); + buf[ret++] = '\n'; + buf[ret] = 0; + } + + return ret; +} + +static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf) +{ + return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset); +} + +static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf) +{ + return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit); +} + +static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf) +{ + int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR); + + return sprintf(buf, "%s\n", autoclear ? "1" : "0"); +} + +LOOP_ATTR_RO(backing_file); +LOOP_ATTR_RO(offset); +LOOP_ATTR_RO(sizelimit); +LOOP_ATTR_RO(autoclear); + +static struct attribute *loop_attrs[] = { + &loop_attr_backing_file.attr, + &loop_attr_offset.attr, + &loop_attr_sizelimit.attr, + &loop_attr_autoclear.attr, + NULL, +}; + +static struct attribute_group loop_attribute_group = { + .name = "loop", + .attrs= loop_attrs, +}; + +static int loop_sysfs_init(struct loop_device *lo) +{ + return sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj, + &loop_attribute_group); +} + +static void loop_sysfs_exit(struct loop_device *lo) +{ + sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj, + &loop_attribute_group); +} + static int loop_set_fd(struct loop_device *lo, fmode_t mode, struct block_device *bdev, unsigned int arg) { @@ -836,6 +934,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode, set_capacity(lo->lo_disk, size); bd_set_size(bdev, size << 9); + loop_sysfs_init(lo); /* let user-space know about the new size */ kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); @@ -854,6 +953,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode, return 0; out_clr: + loop_sysfs_exit(lo); lo->lo_thread = NULL; lo->lo_device = NULL; lo->lo_backing_file = NULL; @@ -950,6 +1050,7 @@ static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev) set_capacity(lo->lo_disk, 0); if (bdev) { bd_set_size(bdev, 0); + loop_sysfs_exit(lo); /* let user-space know about this change */ kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); }