// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 1991-1998  Linus Torvalds
 * Re-organised Feb 1998 Russell King
 * Copyright (C) 2020 Christoph Hellwig
 */
#include <linux/fs.h>
#include <linux/major.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/vmalloc.h>
#include <linux/raid/detect.h>
#include "check.h"

static int (*const check_part[])(struct parsed_partitions *) = {
        /*
         * Probe partition formats with tables at disk address 0
         * that also have an ADFS boot block at 0xdc0.
         */
#ifdef CONFIG_ACORN_PARTITION_ICS
        adfspart_check_ICS,
#endif
#ifdef CONFIG_ACORN_PARTITION_POWERTEC
        adfspart_check_POWERTEC,
#endif
#ifdef CONFIG_ACORN_PARTITION_EESOX
        adfspart_check_EESOX,
#endif

        /*
         * Now move on to formats that only have partition info at
         * disk address 0xdc0.  Since these may also have stale
         * PC/BIOS partition tables, they need to come before
         * the msdos entry.
         */
#ifdef CONFIG_ACORN_PARTITION_CUMANA
        adfspart_check_CUMANA,
#endif
#ifdef CONFIG_ACORN_PARTITION_ADFS
        adfspart_check_ADFS,
#endif

#ifdef CONFIG_CMDLINE_PARTITION
        cmdline_partition,
#endif
#ifdef CONFIG_OF_PARTITION
        of_partition,           /* cmdline have priority to OF */
#endif
#ifdef CONFIG_EFI_PARTITION
        efi_partition,          /* this must come before msdos */
#endif
#ifdef CONFIG_SGI_PARTITION
        sgi_partition,
#endif
#ifdef CONFIG_LDM_PARTITION
        ldm_partition,          /* this must come before msdos */
#endif
#ifdef CONFIG_MSDOS_PARTITION
        msdos_partition,
#endif
#ifdef CONFIG_OSF_PARTITION
        osf_partition,
#endif
#ifdef CONFIG_SUN_PARTITION
        sun_partition,
#endif
#ifdef CONFIG_AMIGA_PARTITION
        amiga_partition,
#endif
#ifdef CONFIG_ATARI_PARTITION
        atari_partition,
#endif
#ifdef CONFIG_MAC_PARTITION
        mac_partition,
#endif
#ifdef CONFIG_ULTRIX_PARTITION
        ultrix_partition,
#endif
#ifdef CONFIG_IBM_PARTITION
        ibm_partition,
#endif
#ifdef CONFIG_KARMA_PARTITION
        karma_partition,
#endif
#ifdef CONFIG_SYSV68_PARTITION
        sysv68_partition,
#endif
        NULL
};

static struct parsed_partitions *allocate_partitions(struct gendisk *hd)
{
        struct parsed_partitions *state;
        int nr = DISK_MAX_PARTS;

        state = kzalloc_obj(*state);
        if (!state)
                return NULL;

        state->parts = vzalloc(array_size(nr, sizeof(state->parts[0])));
        if (!state->parts) {
                kfree(state);
                return NULL;
        }

        state->limit = nr;

        return state;
}

static void free_partitions(struct parsed_partitions *state)
{
        vfree(state->parts);
        kfree(state);
}

static struct parsed_partitions *check_partition(struct gendisk *hd)
{
        struct parsed_partitions *state;
        int i, res, err;

        state = allocate_partitions(hd);
        if (!state)
                return NULL;
        state->pp_buf = (char *)__get_free_page(GFP_KERNEL);
        if (!state->pp_buf) {
                free_partitions(state);
                return NULL;
        }
        state->pp_buf[0] = '\0';

        state->disk = hd;
        strscpy(state->name, hd->disk_name);
        snprintf(state->pp_buf, PAGE_SIZE, " %s:", state->name);
        if (isdigit(state->name[strlen(state->name)-1]))
                sprintf(state->name, "p");

        i = res = err = 0;
        while (!res && check_part[i]) {
                memset(state->parts, 0, state->limit * sizeof(state->parts[0]));
                res = check_part[i++](state);
                if (res < 0) {
                        /*
                         * We have hit an I/O error which we don't report now.
                         * But record it, and let the others do their job.
                         */
                        err = res;
                        res = 0;
                }

        }
        if (res > 0) {
                printk(KERN_INFO "%s", state->pp_buf);

                free_page((unsigned long)state->pp_buf);
                return state;
        }
        if (state->access_beyond_eod)
                err = -ENOSPC;
        /*
         * The partition is unrecognized. So report I/O errors if there were any
         */
        if (err)
                res = err;
        if (res) {
                strlcat(state->pp_buf,
                        " unable to read partition table\n", PAGE_SIZE);
                printk(KERN_INFO "%s", state->pp_buf);
        }

        free_page((unsigned long)state->pp_buf);
        free_partitions(state);
        return ERR_PTR(res);
}

static ssize_t part_partition_show(struct device *dev,
                                   struct device_attribute *attr, char *buf)
{
        return sprintf(buf, "%d\n", bdev_partno(dev_to_bdev(dev)));
}

static ssize_t part_start_show(struct device *dev,
                               struct device_attribute *attr, char *buf)
{
        return sprintf(buf, "%llu\n", dev_to_bdev(dev)->bd_start_sect);
}

static ssize_t part_ro_show(struct device *dev,
                            struct device_attribute *attr, char *buf)
{
        return sprintf(buf, "%d\n", bdev_read_only(dev_to_bdev(dev)));
}

static ssize_t part_alignment_offset_show(struct device *dev,
                                          struct device_attribute *attr, char *buf)
{
        return sprintf(buf, "%u\n", bdev_alignment_offset(dev_to_bdev(dev)));
}

static ssize_t part_discard_alignment_show(struct device *dev,
                                           struct device_attribute *attr, char *buf)
{
        return sprintf(buf, "%u\n", bdev_discard_alignment(dev_to_bdev(dev)));
}

static DEVICE_ATTR(partition, 0444, part_partition_show, NULL);
static DEVICE_ATTR(start, 0444, part_start_show, NULL);
static DEVICE_ATTR(size, 0444, part_size_show, NULL);
static DEVICE_ATTR(ro, 0444, part_ro_show, NULL);
static DEVICE_ATTR(alignment_offset, 0444, part_alignment_offset_show, NULL);
static DEVICE_ATTR(discard_alignment, 0444, part_discard_alignment_show, NULL);
static DEVICE_ATTR(stat, 0444, part_stat_show, NULL);
static DEVICE_ATTR(inflight, 0444, part_inflight_show, NULL);
#ifdef CONFIG_FAIL_MAKE_REQUEST
static struct device_attribute dev_attr_fail =
        __ATTR(make-it-fail, 0644, part_fail_show, part_fail_store);
#endif

static struct attribute *part_attrs[] = {
        &dev_attr_partition.attr,
        &dev_attr_start.attr,
        &dev_attr_size.attr,
        &dev_attr_ro.attr,
        &dev_attr_alignment_offset.attr,
        &dev_attr_discard_alignment.attr,
        &dev_attr_stat.attr,
        &dev_attr_inflight.attr,
#ifdef CONFIG_FAIL_MAKE_REQUEST
        &dev_attr_fail.attr,
#endif
        NULL
};

static const struct attribute_group part_attr_group = {
        .attrs = part_attrs,
};

static const struct attribute_group *part_attr_groups[] = {
        &part_attr_group,
#ifdef CONFIG_BLK_DEV_IO_TRACE
        &blk_trace_attr_group,
#endif
        NULL
};

static void part_release(struct device *dev)
{
        put_disk(dev_to_bdev(dev)->bd_disk);
        bdev_drop(dev_to_bdev(dev));
}

static int part_uevent(const struct device *dev, struct kobj_uevent_env *env)
{
        const struct block_device *part = dev_to_bdev(dev);

        add_uevent_var(env, "PARTN=%u", bdev_partno(part));
        if (part->bd_meta_info && part->bd_meta_info->volname[0])
                add_uevent_var(env, "PARTNAME=%s", part->bd_meta_info->volname);
        if (part->bd_meta_info && part->bd_meta_info->uuid[0])
                add_uevent_var(env, "PARTUUID=%s", part->bd_meta_info->uuid);
        return 0;
}

const struct device_type part_type = {
        .name           = "partition",
        .groups         = part_attr_groups,
        .release        = part_release,
        .uevent         = part_uevent,
};

void drop_partition(struct block_device *part)
{
        lockdep_assert_held(&part->bd_disk->open_mutex);

        xa_erase(&part->bd_disk->part_tbl, bdev_partno(part));
        kobject_put(part->bd_holder_dir);

        device_del(&part->bd_device);
        put_device(&part->bd_device);
}

static ssize_t whole_disk_show(struct device *dev,
                               struct device_attribute *attr, char *buf)
{
        return 0;
}
static const DEVICE_ATTR(whole_disk, 0444, whole_disk_show, NULL);

/*
 * Must be called either with open_mutex held, before a disk can be opened or
 * after all disk users are gone.
 */
static struct block_device *add_partition(struct gendisk *disk, int partno,
                                sector_t start, sector_t len, int flags,
                                struct partition_meta_info *info)
{
        dev_t devt = MKDEV(0, 0);
        struct device *ddev = disk_to_dev(disk);
        struct device *pdev;
        struct block_device *bdev;
        const char *dname;
        int err;

        lockdep_assert_held(&disk->open_mutex);

        if (partno >= DISK_MAX_PARTS)
                return ERR_PTR(-EINVAL);

        /*
         * Partitions are not supported on zoned block devices that are used as
         * such.
         */
        if (bdev_is_zoned(disk->part0)) {
                pr_warn("%s: partitions not supported on host managed zoned block device\n",
                        disk->disk_name);
                return ERR_PTR(-ENXIO);
        }

        if (xa_load(&disk->part_tbl, partno))
                return ERR_PTR(-EBUSY);

        /* ensure we always have a reference to the whole disk */
        get_device(disk_to_dev(disk));

        err = -ENOMEM;
        bdev = bdev_alloc(disk, partno);
        if (!bdev)
                goto out_put_disk;

        bdev->bd_start_sect = start;
        bdev_set_nr_sectors(bdev, len);

        pdev = &bdev->bd_device;
        dname = dev_name(ddev);
        if (isdigit(dname[strlen(dname) - 1]))
                dev_set_name(pdev, "%sp%d", dname, partno);
        else
                dev_set_name(pdev, "%s%d", dname, partno);

        device_initialize(pdev);
        pdev->class = &block_class;
        pdev->type = &part_type;
        pdev->parent = ddev;

        /* in consecutive minor range? */
        if (bdev_partno(bdev) < disk->minors) {
                devt = MKDEV(disk->major, disk->first_minor + bdev_partno(bdev));
        } else {
                err = blk_alloc_ext_minor();
                if (err < 0)
                        goto out_put;
                devt = MKDEV(BLOCK_EXT_MAJOR, err);
        }
        pdev->devt = devt;

        if (info) {
                err = -ENOMEM;
                bdev->bd_meta_info = kmemdup(info, sizeof(*info), GFP_KERNEL);
                if (!bdev->bd_meta_info)
                        goto out_put;
        }

        /* delay uevent until 'holders' subdir is created */
        dev_set_uevent_suppress(pdev, 1);
        err = device_add(pdev);
        if (err)
                goto out_put;

        err = -ENOMEM;
        bdev->bd_holder_dir = kobject_create_and_add("holders", &pdev->kobj);
        if (!bdev->bd_holder_dir)
                goto out_del;

        dev_set_uevent_suppress(pdev, 0);
        if (flags & ADDPART_FLAG_WHOLEDISK) {
                err = device_create_file(pdev, &dev_attr_whole_disk);
                if (err)
                        goto out_del;
        }

        if (flags & ADDPART_FLAG_READONLY)
                bdev_set_flag(bdev, BD_READ_ONLY);

        /* everything is up and running, commence */
        err = xa_insert(&disk->part_tbl, partno, bdev, GFP_KERNEL);
        if (err)
                goto out_del;
        bdev_add(bdev, devt);

        /* suppress uevent if the disk suppresses it */
        if (!dev_get_uevent_suppress(ddev))
                kobject_uevent(&pdev->kobj, KOBJ_ADD);
        return bdev;

out_del:
        kobject_put(bdev->bd_holder_dir);
        device_del(pdev);
out_put:
        put_device(pdev);
        return ERR_PTR(err);
out_put_disk:
        put_disk(disk);
        return ERR_PTR(err);
}

static bool partition_overlaps(struct gendisk *disk, sector_t start,
                sector_t length, int skip_partno)
{
        struct block_device *part;
        bool overlap = false;
        unsigned long idx;

        rcu_read_lock();
        xa_for_each_start(&disk->part_tbl, idx, part, 1) {
                if (bdev_partno(part) != skip_partno &&
                    start < part->bd_start_sect + bdev_nr_sectors(part) &&
                    start + length > part->bd_start_sect) {
                        overlap = true;
                        break;
                }
        }
        rcu_read_unlock();

        return overlap;
}

int bdev_add_partition(struct gendisk *disk, int partno, sector_t start,
                sector_t length)
{
        struct block_device *part;
        int ret;

        mutex_lock(&disk->open_mutex);
        if (!disk_live(disk)) {
                ret = -ENXIO;
                goto out;
        }

        if (disk->flags & GENHD_FL_NO_PART) {
                ret = -EINVAL;
                goto out;
        }

        if (partition_overlaps(disk, start, length, -1)) {
                ret = -EBUSY;
                goto out;
        }

        part = add_partition(disk, partno, start, length,
                        ADDPART_FLAG_NONE, NULL);
        ret = PTR_ERR_OR_ZERO(part);
out:
        mutex_unlock(&disk->open_mutex);
        return ret;
}

int bdev_del_partition(struct gendisk *disk, int partno)
{
        struct block_device *part = NULL;
        int ret = -ENXIO;

        mutex_lock(&disk->open_mutex);
        part = xa_load(&disk->part_tbl, partno);
        if (!part)
                goto out_unlock;

        ret = -EBUSY;
        if (atomic_read(&part->bd_openers))
                goto out_unlock;

        /*
         * We verified that @part->bd_openers is zero above and so
         * @part->bd_holder{_ops} can't be set. And since we hold
         * @disk->open_mutex the device can't be claimed by anyone.
         *
         * So no need to call @part->bd_holder_ops->mark_dead() here.
         * Just delete the partition and invalidate it.
         */

        bdev_unhash(part);
        invalidate_bdev(part);
        drop_partition(part);
        ret = 0;
out_unlock:
        mutex_unlock(&disk->open_mutex);
        return ret;
}

int bdev_resize_partition(struct gendisk *disk, int partno, sector_t start,
                sector_t length)
{
        struct block_device *part = NULL;
        int ret = -ENXIO;

        mutex_lock(&disk->open_mutex);
        part = xa_load(&disk->part_tbl, partno);
        if (!part)
                goto out_unlock;

        ret = -EINVAL;
        if (start != part->bd_start_sect)
                goto out_unlock;

        ret = -EBUSY;
        if (partition_overlaps(disk, start, length, partno))
                goto out_unlock;

        bdev_set_nr_sectors(part, length);

        ret = 0;
out_unlock:
        mutex_unlock(&disk->open_mutex);
        return ret;
}

static bool disk_unlock_native_capacity(struct gendisk *disk)
{
        if (!disk->fops->unlock_native_capacity ||
            test_and_set_bit(GD_NATIVE_CAPACITY, &disk->state)) {
                printk(KERN_CONT "truncated\n");
                return false;
        }

        printk(KERN_CONT "enabling native capacity\n");
        disk->fops->unlock_native_capacity(disk);
        return true;
}

static bool blk_add_partition(struct gendisk *disk,
                struct parsed_partitions *state, int p)
{
        sector_t size = state->parts[p].size;
        sector_t from = state->parts[p].from;
        struct block_device *part;

        if (!size)
                return true;

        if (from >= get_capacity(disk)) {
                printk(KERN_WARNING
                       "%s: p%d start %llu is beyond EOD, ",
                       disk->disk_name, p, (unsigned long long) from);
                if (disk_unlock_native_capacity(disk))
                        return false;
                return true;
        }

        if (from + size > get_capacity(disk)) {
                printk(KERN_WARNING
                       "%s: p%d size %llu extends beyond EOD, ",
                       disk->disk_name, p, (unsigned long long) size);

                if (disk_unlock_native_capacity(disk))
                        return false;

                /*
                 * We can not ignore partitions of broken tables created by for
                 * example camera firmware, but we limit them to the end of the
                 * disk to avoid creating invalid block devices.
                 */
                size = get_capacity(disk) - from;
        }

        part = add_partition(disk, p, from, size, state->parts[p].flags,
                             &state->parts[p].info);
        if (IS_ERR(part)) {
                if (PTR_ERR(part) != -ENXIO) {
                        printk(KERN_ERR " %s: p%d could not be added: %pe\n",
                               disk->disk_name, p, part);
                }
                return true;
        }

        if (IS_BUILTIN(CONFIG_BLK_DEV_MD) &&
            (state->parts[p].flags & ADDPART_FLAG_RAID))
                md_autodetect_dev(part->bd_dev);

        return true;
}

static int blk_add_partitions(struct gendisk *disk)
{
        struct parsed_partitions *state;
        int ret = -EAGAIN, p;

        if (!disk_has_partscan(disk))
                return 0;

        state = check_partition(disk);
        if (!state)
                return 0;
        if (IS_ERR(state)) {
                /*
                 * I/O error reading the partition table.  If we tried to read
                 * beyond EOD, retry after unlocking the native capacity.
                 */
                if (PTR_ERR(state) == -ENOSPC) {
                        printk(KERN_WARNING "%s: partition table beyond EOD, ",
                               disk->disk_name);
                        if (disk_unlock_native_capacity(disk))
                                return -EAGAIN;
                }
                return -EIO;
        }

        /*
         * Partitions are not supported on host managed zoned block devices.
         */
        if (bdev_is_zoned(disk->part0)) {
                pr_warn("%s: ignoring partition table on host managed zoned block device\n",
                        disk->disk_name);
                ret = 0;
                goto out_free_state;
        }

        /*
         * If we read beyond EOD, try unlocking native capacity even if the
         * partition table was successfully read as we could be missing some
         * partitions.
         */
        if (state->access_beyond_eod) {
                printk(KERN_WARNING
                       "%s: partition table partially beyond EOD, ",
                       disk->disk_name);
                if (disk_unlock_native_capacity(disk))
                        goto out_free_state;
        }

        /* tell userspace that the media / partition table may have changed */
        kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);

        for (p = 1; p < state->limit; p++)
                if (!blk_add_partition(disk, state, p))
                        goto out_free_state;

        ret = 0;
out_free_state:
        free_partitions(state);
        return ret;
}

int bdev_disk_changed(struct gendisk *disk, bool invalidate)
{
        struct block_device *part;
        unsigned long idx;
        int ret = 0;

        lockdep_assert_held(&disk->open_mutex);

        if (!disk_live(disk))
                return -ENXIO;

rescan:
        if (disk->open_partitions)
                return -EBUSY;
        sync_blockdev(disk->part0);
        invalidate_bdev(disk->part0);

        xa_for_each_start(&disk->part_tbl, idx, part, 1) {
                /*
                 * Remove the block device from the inode hash, so that
                 * it cannot be looked up any more even when openers
                 * still hold references.
                 */
                bdev_unhash(part);

                /*
                 * If @disk->open_partitions isn't elevated but there's
                 * still an active holder of that block device things
                 * are broken.
                 */
                WARN_ON_ONCE(atomic_read(&part->bd_openers));
                invalidate_bdev(part);
                drop_partition(part);
        }
        clear_bit(GD_NEED_PART_SCAN, &disk->state);

        /*
         * Historically we only set the capacity to zero for devices that
         * support partitions (independ of actually having partitions created).
         * Doing that is rather inconsistent, but changing it broke legacy
         * udisks polling for legacy ide-cdrom devices.  Use the crude check
         * below to get the sane behavior for most device while not breaking
         * userspace for this particular setup.
         */
        if (invalidate) {
                if (!(disk->flags & GENHD_FL_NO_PART) ||
                    !(disk->flags & GENHD_FL_REMOVABLE))
                        set_capacity(disk, 0);
        }

        if (get_capacity(disk)) {
                ret = blk_add_partitions(disk);
                if (ret == -EAGAIN)
                        goto rescan;
        } else if (invalidate) {
                /*
                 * Tell userspace that the media / partition table may have
                 * changed.
                 */
                kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
        }

        return ret;
}
/*
 * Only exported for loop and dasd for historic reasons.  Don't use in new
 * code!
 */
EXPORT_SYMBOL_GPL(bdev_disk_changed);

void *read_part_sector(struct parsed_partitions *state, sector_t n, Sector *p)
{
        struct address_space *mapping = state->disk->part0->bd_mapping;
        struct folio *folio;

        if (n >= get_capacity(state->disk)) {
                state->access_beyond_eod = true;
                goto out;
        }

        folio = read_mapping_folio(mapping, n >> PAGE_SECTORS_SHIFT, NULL);
        if (IS_ERR(folio))
                goto out;

        p->v = folio;
        return folio_address(folio) + offset_in_folio(folio, n * SECTOR_SIZE);
out:
        p->v = NULL;
        return NULL;
}