linux/drivers/block/loop.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Copyright 1993 by Theodore Ts'o.
   4 */
   5#include <linux/module.h>
   6#include <linux/moduleparam.h>
   7#include <linux/sched.h>
   8#include <linux/fs.h>
   9#include <linux/pagemap.h>
  10#include <linux/file.h>
  11#include <linux/stat.h>
  12#include <linux/errno.h>
  13#include <linux/major.h>
  14#include <linux/wait.h>
  15#include <linux/blkpg.h>
  16#include <linux/init.h>
  17#include <linux/swap.h>
  18#include <linux/slab.h>
  19#include <linux/compat.h>
  20#include <linux/suspend.h>
  21#include <linux/freezer.h>
  22#include <linux/mutex.h>
  23#include <linux/writeback.h>
  24#include <linux/completion.h>
  25#include <linux/highmem.h>
  26#include <linux/splice.h>
  27#include <linux/sysfs.h>
  28#include <linux/miscdevice.h>
  29#include <linux/falloc.h>
  30#include <linux/uio.h>
  31#include <linux/ioprio.h>
  32#include <linux/blk-cgroup.h>
  33#include <linux/sched/mm.h>
  34#include <linux/statfs.h>
  35#include <linux/uaccess.h>
  36#include <linux/blk-mq.h>
  37#include <linux/spinlock.h>
  38#include <uapi/linux/loop.h>
  39
  40/* Possible states of device */
  41enum {
  42        Lo_unbound,
  43        Lo_bound,
  44        Lo_rundown,
  45        Lo_deleting,
  46};
  47
  48struct loop_func_table;
  49
  50struct loop_device {
  51        int             lo_number;
  52        loff_t          lo_offset;
  53        loff_t          lo_sizelimit;
  54        int             lo_flags;
  55        char            lo_file_name[LO_NAME_SIZE];
  56
  57        struct file *   lo_backing_file;
  58        struct block_device *lo_device;
  59
  60        gfp_t           old_gfp_mask;
  61
  62        spinlock_t              lo_lock;
  63        int                     lo_state;
  64        spinlock_t              lo_work_lock;
  65        struct workqueue_struct *workqueue;
  66        struct work_struct      rootcg_work;
  67        struct list_head        rootcg_cmd_list;
  68        struct list_head        idle_worker_list;
  69        struct rb_root          worker_tree;
  70        struct timer_list       timer;
  71        bool                    use_dio;
  72        bool                    sysfs_inited;
  73
  74        struct request_queue    *lo_queue;
  75        struct blk_mq_tag_set   tag_set;
  76        struct gendisk          *lo_disk;
  77        struct mutex            lo_mutex;
  78        bool                    idr_visible;
  79};
  80
  81struct loop_cmd {
  82        struct list_head list_entry;
  83        bool use_aio; /* use AIO interface to handle I/O */
  84        atomic_t ref; /* only for aio */
  85        long ret;
  86        struct kiocb iocb;
  87        struct bio_vec *bvec;
  88        struct cgroup_subsys_state *blkcg_css;
  89        struct cgroup_subsys_state *memcg_css;
  90};
  91
  92#define LOOP_IDLE_WORKER_TIMEOUT (60 * HZ)
  93#define LOOP_DEFAULT_HW_Q_DEPTH 128
  94
  95static DEFINE_IDR(loop_index_idr);
  96static DEFINE_MUTEX(loop_ctl_mutex);
  97static DEFINE_MUTEX(loop_validate_mutex);
  98
  99/**
 100 * loop_global_lock_killable() - take locks for safe loop_validate_file() test
 101 *
 102 * @lo: struct loop_device
 103 * @global: true if @lo is about to bind another "struct loop_device", false otherwise
 104 *
 105 * Returns 0 on success, -EINTR otherwise.
 106 *
 107 * Since loop_validate_file() traverses on other "struct loop_device" if
 108 * is_loop_device() is true, we need a global lock for serializing concurrent
 109 * loop_configure()/loop_change_fd()/__loop_clr_fd() calls.
 110 */
 111static int loop_global_lock_killable(struct loop_device *lo, bool global)
 112{
 113        int err;
 114
 115        if (global) {
 116                err = mutex_lock_killable(&loop_validate_mutex);
 117                if (err)
 118                        return err;
 119        }
 120        err = mutex_lock_killable(&lo->lo_mutex);
 121        if (err && global)
 122                mutex_unlock(&loop_validate_mutex);
 123        return err;
 124}
 125
 126/**
 127 * loop_global_unlock() - release locks taken by loop_global_lock_killable()
 128 *
 129 * @lo: struct loop_device
 130 * @global: true if @lo was about to bind another "struct loop_device", false otherwise
 131 */
 132static void loop_global_unlock(struct loop_device *lo, bool global)
 133{
 134        mutex_unlock(&lo->lo_mutex);
 135        if (global)
 136                mutex_unlock(&loop_validate_mutex);
 137}
 138
 139static int max_part;
 140static int part_shift;
 141
 142static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file)
 143{
 144        loff_t loopsize;
 145
 146        /* Compute loopsize in bytes */
 147        loopsize = i_size_read(file->f_mapping->host);
 148        if (offset > 0)
 149                loopsize -= offset;
 150        /* offset is beyond i_size, weird but possible */
 151        if (loopsize < 0)
 152                return 0;
 153
 154        if (sizelimit > 0 && sizelimit < loopsize)
 155                loopsize = sizelimit;
 156        /*
 157         * Unfortunately, if we want to do I/O on the device,
 158         * the number of 512-byte sectors has to fit into a sector_t.
 159         */
 160        return loopsize >> 9;
 161}
 162
 163static loff_t get_loop_size(struct loop_device *lo, struct file *file)
 164{
 165        return get_size(lo->lo_offset, lo->lo_sizelimit, file);
 166}
 167
 168static void __loop_update_dio(struct loop_device *lo, bool dio)
 169{
 170        struct file *file = lo->lo_backing_file;
 171        struct address_space *mapping = file->f_mapping;
 172        struct inode *inode = mapping->host;
 173        unsigned short sb_bsize = 0;
 174        unsigned dio_align = 0;
 175        bool use_dio;
 176
 177        if (inode->i_sb->s_bdev) {
 178                sb_bsize = bdev_logical_block_size(inode->i_sb->s_bdev);
 179                dio_align = sb_bsize - 1;
 180        }
 181
 182        /*
 183         * We support direct I/O only if lo_offset is aligned with the
 184         * logical I/O size of backing device, and the logical block
 185         * size of loop is bigger than the backing device's.
 186         *
 187         * TODO: the above condition may be loosed in the future, and
 188         * direct I/O may be switched runtime at that time because most
 189         * of requests in sane applications should be PAGE_SIZE aligned
 190         */
 191        if (dio) {
 192                if (queue_logical_block_size(lo->lo_queue) >= sb_bsize &&
 193                    !(lo->lo_offset & dio_align) &&
 194                    (file->f_mode & FMODE_CAN_ODIRECT))
 195                        use_dio = true;
 196                else
 197                        use_dio = false;
 198        } else {
 199                use_dio = false;
 200        }
 201
 202        if (lo->use_dio == use_dio)
 203                return;
 204
 205        /* flush dirty pages before changing direct IO */
 206        vfs_fsync(file, 0);
 207
 208        /*
 209         * The flag of LO_FLAGS_DIRECT_IO is handled similarly with
 210         * LO_FLAGS_READ_ONLY, both are set from kernel, and losetup
 211         * will get updated by ioctl(LOOP_GET_STATUS)
 212         */
 213        if (lo->lo_state == Lo_bound)
 214                blk_mq_freeze_queue(lo->lo_queue);
 215        lo->use_dio = use_dio;
 216        if (use_dio) {
 217                blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, lo->lo_queue);
 218                lo->lo_flags |= LO_FLAGS_DIRECT_IO;
 219        } else {
 220                blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue);
 221                lo->lo_flags &= ~LO_FLAGS_DIRECT_IO;
 222        }
 223        if (lo->lo_state == Lo_bound)
 224                blk_mq_unfreeze_queue(lo->lo_queue);
 225}
 226
 227/**
 228 * loop_set_size() - sets device size and notifies userspace
 229 * @lo: struct loop_device to set the size for
 230 * @size: new size of the loop device
 231 *
 232 * Callers must validate that the size passed into this function fits into
 233 * a sector_t, eg using loop_validate_size()
 234 */
 235static void loop_set_size(struct loop_device *lo, loff_t size)
 236{
 237        if (!set_capacity_and_notify(lo->lo_disk, size))
 238                kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE);
 239}
 240
 241static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos)
 242{
 243        struct iov_iter i;
 244        ssize_t bw;
 245
 246        iov_iter_bvec(&i, ITER_SOURCE, bvec, 1, bvec->bv_len);
 247
 248        file_start_write(file);
 249        bw = vfs_iter_write(file, &i, ppos, 0);
 250        file_end_write(file);
 251
 252        if (likely(bw ==  bvec->bv_len))
 253                return 0;
 254
 255        printk_ratelimited(KERN_ERR
 256                "loop: Write error at byte offset %llu, length %i.\n",
 257                (unsigned long long)*ppos, bvec->bv_len);
 258        if (bw >= 0)
 259                bw = -EIO;
 260        return bw;
 261}
 262
 263static int lo_write_simple(struct loop_device *lo, struct request *rq,
 264                loff_t pos)
 265{
 266        struct bio_vec bvec;
 267        struct req_iterator iter;
 268        int ret = 0;
 269
 270        rq_for_each_segment(bvec, rq, iter) {
 271                ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos);
 272                if (ret < 0)
 273                        break;
 274                cond_resched();
 275        }
 276
 277        return ret;
 278}
 279
 280static int lo_read_simple(struct loop_device *lo, struct request *rq,
 281                loff_t pos)
 282{
 283        struct bio_vec bvec;
 284        struct req_iterator iter;
 285        struct iov_iter i;
 286        ssize_t len;
 287
 288        rq_for_each_segment(bvec, rq, iter) {
 289                iov_iter_bvec(&i, ITER_DEST, &bvec, 1, bvec.bv_len);
 290                len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0);
 291                if (len < 0)
 292                        return len;
 293
 294                flush_dcache_page(bvec.bv_page);
 295
 296                if (len != bvec.bv_len) {
 297                        struct bio *bio;
 298
 299                        __rq_for_each_bio(bio, rq)
 300                                zero_fill_bio(bio);
 301                        break;
 302                }
 303                cond_resched();
 304        }
 305
 306        return 0;
 307}
 308
 309static int lo_fallocate(struct loop_device *lo, struct request *rq, loff_t pos,
 310                        int mode)
 311{
 312        /*
 313         * We use fallocate to manipulate the space mappings used by the image
 314         * a.k.a. discard/zerorange.
 315         */
 316        struct file *file = lo->lo_backing_file;
 317        int ret;
 318
 319        mode |= FALLOC_FL_KEEP_SIZE;
 320
 321        if (!bdev_max_discard_sectors(lo->lo_device))
 322                return -EOPNOTSUPP;
 323
 324        ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq));
 325        if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP))
 326                return -EIO;
 327        return ret;
 328}
 329
 330static int lo_req_flush(struct loop_device *lo, struct request *rq)
 331{
 332        int ret = vfs_fsync(lo->lo_backing_file, 0);
 333        if (unlikely(ret && ret != -EINVAL))
 334                ret = -EIO;
 335
 336        return ret;
 337}
 338
 339static void lo_complete_rq(struct request *rq)
 340{
 341        struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
 342        blk_status_t ret = BLK_STS_OK;
 343
 344        if (!cmd->use_aio || cmd->ret < 0 || cmd->ret == blk_rq_bytes(rq) ||
 345            req_op(rq) != REQ_OP_READ) {
 346                if (cmd->ret < 0)
 347                        ret = errno_to_blk_status(cmd->ret);
 348                goto end_io;
 349        }
 350
 351        /*
 352         * Short READ - if we got some data, advance our request and
 353         * retry it. If we got no data, end the rest with EIO.
 354         */
 355        if (cmd->ret) {
 356                blk_update_request(rq, BLK_STS_OK, cmd->ret);
 357                cmd->ret = 0;
 358                blk_mq_requeue_request(rq, true);
 359        } else {
 360                if (cmd->use_aio) {
 361                        struct bio *bio = rq->bio;
 362
 363                        while (bio) {
 364                                zero_fill_bio(bio);
 365                                bio = bio->bi_next;
 366                        }
 367                }
 368                ret = BLK_STS_IOERR;
 369end_io:
 370                blk_mq_end_request(rq, ret);
 371        }
 372}
 373
 374static void lo_rw_aio_do_completion(struct loop_cmd *cmd)
 375{
 376        struct request *rq = blk_mq_rq_from_pdu(cmd);
 377
 378        if (!atomic_dec_and_test(&cmd->ref))
 379                return;
 380        kfree(cmd->bvec);
 381        cmd->bvec = NULL;
 382        if (likely(!blk_should_fake_timeout(rq->q)))
 383                blk_mq_complete_request(rq);
 384}
 385
 386static void lo_rw_aio_complete(struct kiocb *iocb, long ret)
 387{
 388        struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb);
 389
 390        cmd->ret = ret;
 391        lo_rw_aio_do_completion(cmd);
 392}
 393
 394static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
 395                     loff_t pos, int rw)
 396{
 397        struct iov_iter iter;
 398        struct req_iterator rq_iter;
 399        struct bio_vec *bvec;
 400        struct request *rq = blk_mq_rq_from_pdu(cmd);
 401        struct bio *bio = rq->bio;
 402        struct file *file = lo->lo_backing_file;
 403        struct bio_vec tmp;
 404        unsigned int offset;
 405        int nr_bvec = 0;
 406        int ret;
 407
 408        rq_for_each_bvec(tmp, rq, rq_iter)
 409                nr_bvec++;
 410
 411        if (rq->bio != rq->biotail) {
 412
 413                bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec),
 414                                     GFP_NOIO);
 415                if (!bvec)
 416                        return -EIO;
 417                cmd->bvec = bvec;
 418
 419                /*
 420                 * The bios of the request may be started from the middle of
 421                 * the 'bvec' because of bio splitting, so we can't directly
 422                 * copy bio->bi_iov_vec to new bvec. The rq_for_each_bvec
 423                 * API will take care of all details for us.
 424                 */
 425                rq_for_each_bvec(tmp, rq, rq_iter) {
 426                        *bvec = tmp;
 427                        bvec++;
 428                }
 429                bvec = cmd->bvec;
 430                offset = 0;
 431        } else {
 432                /*
 433                 * Same here, this bio may be started from the middle of the
 434                 * 'bvec' because of bio splitting, so offset from the bvec
 435                 * must be passed to iov iterator
 436                 */
 437                offset = bio->bi_iter.bi_bvec_done;
 438                bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
 439        }
 440        atomic_set(&cmd->ref, 2);
 441
 442        iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq));
 443        iter.iov_offset = offset;
 444
 445        cmd->iocb.ki_pos = pos;
 446        cmd->iocb.ki_filp = file;
 447        cmd->iocb.ki_complete = lo_rw_aio_complete;
 448        cmd->iocb.ki_flags = IOCB_DIRECT;
 449        cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
 450
 451        if (rw == ITER_SOURCE)
 452                ret = call_write_iter(file, &cmd->iocb, &iter);
 453        else
 454                ret = call_read_iter(file, &cmd->iocb, &iter);
 455
 456        lo_rw_aio_do_completion(cmd);
 457
 458        if (ret != -EIOCBQUEUED)
 459                lo_rw_aio_complete(&cmd->iocb, ret);
 460        return 0;
 461}
 462
 463static int do_req_filebacked(struct loop_device *lo, struct request *rq)
 464{
 465        struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
 466        loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;
 467
 468        /*
 469         * lo_write_simple and lo_read_simple should have been covered
 470         * by io submit style function like lo_rw_aio(), one blocker
 471         * is that lo_read_simple() need to call flush_dcache_page after
 472         * the page is written from kernel, and it isn't easy to handle
 473         * this in io submit style function which submits all segments
 474         * of the req at one time. And direct read IO doesn't need to
 475         * run flush_dcache_page().
 476         */
 477        switch (req_op(rq)) {
 478        case REQ_OP_FLUSH:
 479                return lo_req_flush(lo, rq);
 480        case REQ_OP_WRITE_ZEROES:
 481                /*
 482                 * If the caller doesn't want deallocation, call zeroout to
 483                 * write zeroes the range.  Otherwise, punch them out.
 484                 */
 485                return lo_fallocate(lo, rq, pos,
 486                        (rq->cmd_flags & REQ_NOUNMAP) ?
 487                                FALLOC_FL_ZERO_RANGE :
 488                                FALLOC_FL_PUNCH_HOLE);
 489        case REQ_OP_DISCARD:
 490                return lo_fallocate(lo, rq, pos, FALLOC_FL_PUNCH_HOLE);
 491        case REQ_OP_WRITE:
 492                if (cmd->use_aio)
 493                        return lo_rw_aio(lo, cmd, pos, ITER_SOURCE);
 494                else
 495                        return lo_write_simple(lo, rq, pos);
 496        case REQ_OP_READ:
 497                if (cmd->use_aio)
 498                        return lo_rw_aio(lo, cmd, pos, ITER_DEST);
 499                else
 500                        return lo_read_simple(lo, rq, pos);
 501        default:
 502                WARN_ON_ONCE(1);
 503                return -EIO;
 504        }
 505}
 506
 507static inline void loop_update_dio(struct loop_device *lo)
 508{
 509        __loop_update_dio(lo, (lo->lo_backing_file->f_flags & O_DIRECT) |
 510                                lo->use_dio);
 511}
 512
 513static void loop_reread_partitions(struct loop_device *lo)
 514{
 515        int rc;
 516
 517        mutex_lock(&lo->lo_disk->open_mutex);
 518        rc = bdev_disk_changed(lo->lo_disk, false);
 519        mutex_unlock(&lo->lo_disk->open_mutex);
 520        if (rc)
 521                pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n",
 522                        __func__, lo->lo_number, lo->lo_file_name, rc);
 523}
 524
 525static inline int is_loop_device(struct file *file)
 526{
 527        struct inode *i = file->f_mapping->host;
 528
 529        return i && S_ISBLK(i->i_mode) && imajor(i) == LOOP_MAJOR;
 530}
 531
 532static int loop_validate_file(struct file *file, struct block_device *bdev)
 533{
 534        struct inode    *inode = file->f_mapping->host;
 535        struct file     *f = file;
 536
 537        /* Avoid recursion */
 538        while (is_loop_device(f)) {
 539                struct loop_device *l;
 540
 541                lockdep_assert_held(&loop_validate_mutex);
 542                if (f->f_mapping->host->i_rdev == bdev->bd_dev)
 543                        return -EBADF;
 544
 545                l = I_BDEV(f->f_mapping->host)->bd_disk->private_data;
 546                if (l->lo_state != Lo_bound)
 547                        return -EINVAL;
 548                /* Order wrt setting lo->lo_backing_file in loop_configure(). */
 549                rmb();
 550                f = l->lo_backing_file;
 551        }
 552        if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
 553                return -EINVAL;
 554        return 0;
 555}
 556
 557/*
 558 * loop_change_fd switched the backing store of a loopback device to
 559 * a new file. This is useful for operating system installers to free up
 560 * the original file and in High Availability environments to switch to
 561 * an alternative location for the content in case of server meltdown.
 562 * This can only work if the loop device is used read-only, and if the
 563 * new backing store is the same size and type as the old backing store.
 564 */
 565static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
 566                          unsigned int arg)
 567{
 568        struct file *file = fget(arg);
 569        struct file *old_file;
 570        int error;
 571        bool partscan;
 572        bool is_loop;
 573
 574        if (!file)
 575                return -EBADF;
 576
 577        /* suppress uevents while reconfiguring the device */
 578        dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1);
 579
 580        is_loop = is_loop_device(file);
 581        error = loop_global_lock_killable(lo, is_loop);
 582        if (error)
 583                goto out_putf;
 584        error = -ENXIO;
 585        if (lo->lo_state != Lo_bound)
 586                goto out_err;
 587
 588        /* the loop device has to be read-only */
 589        error = -EINVAL;
 590        if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
 591                goto out_err;
 592
 593        error = loop_validate_file(file, bdev);
 594        if (error)
 595                goto out_err;
 596
 597        old_file = lo->lo_backing_file;
 598
 599        error = -EINVAL;
 600
 601        /* size of the new backing store needs to be the same */
 602        if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
 603                goto out_err;
 604
 605        /* and ... switch */
 606        disk_force_media_change(lo->lo_disk);
 607        blk_mq_freeze_queue(lo->lo_queue);
 608        mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
 609        lo->lo_backing_file = file;
 610        lo->old_gfp_mask = mapping_gfp_mask(file->f_mapping);
 611        mapping_set_gfp_mask(file->f_mapping,
 612                             lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
 613        loop_update_dio(lo);
 614        blk_mq_unfreeze_queue(lo->lo_queue);
 615        partscan = lo->lo_flags & LO_FLAGS_PARTSCAN;
 616        loop_global_unlock(lo, is_loop);
 617
 618        /*
 619         * Flush loop_validate_file() before fput(), for l->lo_backing_file
 620         * might be pointing at old_file which might be the last reference.
 621         */
 622        if (!is_loop) {
 623                mutex_lock(&loop_validate_mutex);
 624                mutex_unlock(&loop_validate_mutex);
 625        }
 626        /*
 627         * We must drop file reference outside of lo_mutex as dropping
 628         * the file ref can take open_mutex which creates circular locking
 629         * dependency.
 630         */
 631        fput(old_file);
 632        if (partscan)
 633                loop_reread_partitions(lo);
 634
 635        error = 0;
 636done:
 637        /* enable and uncork uevent now that we are done */
 638        dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0);
 639        return error;
 640
 641out_err:
 642        loop_global_unlock(lo, is_loop);
 643out_putf:
 644        fput(file);
 645        goto done;
 646}
 647
 648/* loop sysfs attributes */
 649
 650static ssize_t loop_attr_show(struct device *dev, char *page,
 651                              ssize_t (*callback)(struct loop_device *, char *))
 652{
 653        struct gendisk *disk = dev_to_disk(dev);
 654        struct loop_device *lo = disk->private_data;
 655
 656        return callback(lo, page);
 657}
 658
 659#define LOOP_ATTR_RO(_name)                                             \
 660static ssize_t loop_attr_##_name##_show(struct loop_device *, char *);  \
 661static ssize_t loop_attr_do_show_##_name(struct device *d,              \
 662                                struct device_attribute *attr, char *b) \
 663{                                                                       \
 664        return loop_attr_show(d, b, loop_attr_##_name##_show);          \
 665}                                                                       \
 666static struct device_attribute loop_attr_##_name =                      \
 667        __ATTR(_name, 0444, loop_attr_do_show_##_name, NULL);
 668
 669static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
 670{
 671        ssize_t ret;
 672        char *p = NULL;
 673
 674        spin_lock_irq(&lo->lo_lock);
 675        if (lo->lo_backing_file)
 676                p = file_path(lo->lo_backing_file, buf, PAGE_SIZE - 1);
 677        spin_unlock_irq(&lo->lo_lock);
 678
 679        if (IS_ERR_OR_NULL(p))
 680                ret = PTR_ERR(p);
 681        else {
 682                ret = strlen(p);
 683                memmove(buf, p, ret);
 684                buf[ret++] = '\n';
 685                buf[ret] = 0;
 686        }
 687
 688        return ret;
 689}
 690
 691static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
 692{
 693        return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_offset);
 694}
 695
 696static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
 697{
 698        return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
 699}
 700
 701static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
 702{
 703        int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
 704
 705        return sysfs_emit(buf, "%s\n", autoclear ? "1" : "0");
 706}
 707
 708static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
 709{
 710        int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
 711
 712        return sysfs_emit(buf, "%s\n", partscan ? "1" : "0");
 713}
 714
 715static ssize_t loop_attr_dio_show(struct loop_device *lo, char *buf)
 716{
 717        int dio = (lo->lo_flags & LO_FLAGS_DIRECT_IO);
 718
 719        return sysfs_emit(buf, "%s\n", dio ? "1" : "0");
 720}
 721
 722LOOP_ATTR_RO(backing_file);
 723LOOP_ATTR_RO(offset);
 724LOOP_ATTR_RO(sizelimit);
 725LOOP_ATTR_RO(autoclear);
 726LOOP_ATTR_RO(partscan);
 727LOOP_ATTR_RO(dio);
 728
 729static struct attribute *loop_attrs[] = {
 730        &loop_attr_backing_file.attr,
 731        &loop_attr_offset.attr,
 732        &loop_attr_sizelimit.attr,
 733        &loop_attr_autoclear.attr,
 734        &loop_attr_partscan.attr,
 735        &loop_attr_dio.attr,
 736        NULL,
 737};
 738
 739static struct attribute_group loop_attribute_group = {
 740        .name = "loop",
 741        .attrs= loop_attrs,
 742};
 743
 744static void loop_sysfs_init(struct loop_device *lo)
 745{
 746        lo->sysfs_inited = !sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
 747                                                &loop_attribute_group);
 748}
 749
 750static void loop_sysfs_exit(struct loop_device *lo)
 751{
 752        if (lo->sysfs_inited)
 753                sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
 754                                   &loop_attribute_group);
 755}
 756
 757static void loop_config_discard(struct loop_device *lo)
 758{
 759        struct file *file = lo->lo_backing_file;
 760        struct inode *inode = file->f_mapping->host;
 761        struct request_queue *q = lo->lo_queue;
 762        u32 granularity, max_discard_sectors;
 763
 764        /*
 765         * If the backing device is a block device, mirror its zeroing
 766         * capability. Set the discard sectors to the block device's zeroing
 767         * capabilities because loop discards result in blkdev_issue_zeroout(),
 768         * not blkdev_issue_discard(). This maintains consistent behavior with
 769         * file-backed loop devices: discarded regions read back as zero.
 770         */
 771        if (S_ISBLK(inode->i_mode)) {
 772                struct request_queue *backingq = bdev_get_queue(I_BDEV(inode));
 773
 774                max_discard_sectors = backingq->limits.max_write_zeroes_sectors;
 775                granularity = bdev_discard_granularity(I_BDEV(inode)) ?:
 776                        queue_physical_block_size(backingq);
 777
 778        /*
 779         * We use punch hole to reclaim the free space used by the
 780         * image a.k.a. discard.
 781         */
 782        } else if (!file->f_op->fallocate) {
 783                max_discard_sectors = 0;
 784                granularity = 0;
 785
 786        } else {
 787                struct kstatfs sbuf;
 788
 789                max_discard_sectors = UINT_MAX >> 9;
 790                if (!vfs_statfs(&file->f_path, &sbuf))
 791                        granularity = sbuf.f_bsize;
 792                else
 793                        max_discard_sectors = 0;
 794        }
 795
 796        if (max_discard_sectors) {
 797                q->limits.discard_granularity = granularity;
 798                blk_queue_max_discard_sectors(q, max_discard_sectors);
 799                blk_queue_max_write_zeroes_sectors(q, max_discard_sectors);
 800        } else {
 801                q->limits.discard_granularity = 0;
 802                blk_queue_max_discard_sectors(q, 0);
 803                blk_queue_max_write_zeroes_sectors(q, 0);
 804        }
 805}
 806
 807struct loop_worker {
 808        struct rb_node rb_node;
 809        struct work_struct work;
 810        struct list_head cmd_list;
 811        struct list_head idle_list;
 812        struct loop_device *lo;
 813        struct cgroup_subsys_state *blkcg_css;
 814        unsigned long last_ran_at;
 815};
 816
 817static void loop_workfn(struct work_struct *work);
 818
 819#ifdef CONFIG_BLK_CGROUP
 820static inline int queue_on_root_worker(struct cgroup_subsys_state *css)
 821{
 822        return !css || css == blkcg_root_css;
 823}
 824#else
 825static inline int queue_on_root_worker(struct cgroup_subsys_state *css)
 826{
 827        return !css;
 828}
 829#endif
 830
 831static void loop_queue_work(struct loop_device *lo, struct loop_cmd *cmd)
 832{
 833        struct rb_node **node, *parent = NULL;
 834        struct loop_worker *cur_worker, *worker = NULL;
 835        struct work_struct *work;
 836        struct list_head *cmd_list;
 837
 838        spin_lock_irq(&lo->lo_work_lock);
 839
 840        if (queue_on_root_worker(cmd->blkcg_css))
 841                goto queue_work;
 842
 843        node = &lo->worker_tree.rb_node;
 844
 845        while (*node) {
 846                parent = *node;
 847                cur_worker = container_of(*node, struct loop_worker, rb_node);
 848                if (cur_worker->blkcg_css == cmd->blkcg_css) {
 849                        worker = cur_worker;
 850                        break;
 851                } else if ((long)cur_worker->blkcg_css < (long)cmd->blkcg_css) {
 852                        node = &(*node)->rb_left;
 853                } else {
 854                        node = &(*node)->rb_right;
 855                }
 856        }
 857        if (worker)
 858                goto queue_work;
 859
 860        worker = kzalloc(sizeof(struct loop_worker), GFP_NOWAIT | __GFP_NOWARN);
 861        /*
 862         * In the event we cannot allocate a worker, just queue on the
 863         * rootcg worker and issue the I/O as the rootcg
 864         */
 865        if (!worker) {
 866                cmd->blkcg_css = NULL;
 867                if (cmd->memcg_css)
 868                        css_put(cmd->memcg_css);
 869                cmd->memcg_css = NULL;
 870                goto queue_work;
 871        }
 872
 873        worker->blkcg_css = cmd->blkcg_css;
 874        css_get(worker->blkcg_css);
 875        INIT_WORK(&worker->work, loop_workfn);
 876        INIT_LIST_HEAD(&worker->cmd_list);
 877        INIT_LIST_HEAD(&worker->idle_list);
 878        worker->lo = lo;
 879        rb_link_node(&worker->rb_node, parent, node);
 880        rb_insert_color(&worker->rb_node, &lo->worker_tree);
 881queue_work:
 882        if (worker) {
 883                /*
 884                 * We need to remove from the idle list here while
 885                 * holding the lock so that the idle timer doesn't
 886                 * free the worker
 887                 */
 888                if (!list_empty(&worker->idle_list))
 889                        list_del_init(&worker->idle_list);
 890                work = &worker->work;
 891                cmd_list = &worker->cmd_list;
 892        } else {
 893                work = &lo->rootcg_work;
 894                cmd_list = &lo->rootcg_cmd_list;
 895        }
 896        list_add_tail(&cmd->list_entry, cmd_list);
 897        queue_work(lo->workqueue, work);
 898        spin_unlock_irq(&lo->lo_work_lock);
 899}
 900
 901static void loop_set_timer(struct loop_device *lo)
 902{
 903        timer_reduce(&lo->timer, jiffies + LOOP_IDLE_WORKER_TIMEOUT);
 904}
 905
 906static void loop_free_idle_workers(struct loop_device *lo, bool delete_all)
 907{
 908        struct loop_worker *pos, *worker;
 909
 910        spin_lock_irq(&lo->lo_work_lock);
 911        list_for_each_entry_safe(worker, pos, &lo->idle_worker_list,
 912                                idle_list) {
 913                if (!delete_all &&
 914                    time_is_after_jiffies(worker->last_ran_at +
 915                                          LOOP_IDLE_WORKER_TIMEOUT))
 916                        break;
 917                list_del(&worker->idle_list);
 918                rb_erase(&worker->rb_node, &lo->worker_tree);
 919                css_put(worker->blkcg_css);
 920                kfree(worker);
 921        }
 922        if (!list_empty(&lo->idle_worker_list))
 923                loop_set_timer(lo);
 924        spin_unlock_irq(&lo->lo_work_lock);
 925}
 926
 927static void loop_free_idle_workers_timer(struct timer_list *timer)
 928{
 929        struct loop_device *lo = container_of(timer, struct loop_device, timer);
 930
 931        return loop_free_idle_workers(lo, false);
 932}
 933
 934static void loop_update_rotational(struct loop_device *lo)
 935{
 936        struct file *file = lo->lo_backing_file;
 937        struct inode *file_inode = file->f_mapping->host;
 938        struct block_device *file_bdev = file_inode->i_sb->s_bdev;
 939        struct request_queue *q = lo->lo_queue;
 940        bool nonrot = true;
 941
 942        /* not all filesystems (e.g. tmpfs) have a sb->s_bdev */
 943        if (file_bdev)
 944                nonrot = bdev_nonrot(file_bdev);
 945
 946        if (nonrot)
 947                blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
 948        else
 949                blk_queue_flag_clear(QUEUE_FLAG_NONROT, q);
 950}
 951
 952/**
 953 * loop_set_status_from_info - configure device from loop_info
 954 * @lo: struct loop_device to configure
 955 * @info: struct loop_info64 to configure the device with
 956 *
 957 * Configures the loop device parameters according to the passed
 958 * in loop_info64 configuration.
 959 */
 960static int
 961loop_set_status_from_info(struct loop_device *lo,
 962                          const struct loop_info64 *info)
 963{
 964        if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
 965                return -EINVAL;
 966
 967        switch (info->lo_encrypt_type) {
 968        case LO_CRYPT_NONE:
 969                break;
 970        case LO_CRYPT_XOR:
 971                pr_warn("support for the xor transformation has been removed.\n");
 972                return -EINVAL;
 973        case LO_CRYPT_CRYPTOAPI:
 974                pr_warn("support for cryptoloop has been removed.  Use dm-crypt instead.\n");
 975                return -EINVAL;
 976        default:
 977                return -EINVAL;
 978        }
 979
 980        /* Avoid assigning overflow values */
 981        if (info->lo_offset > LLONG_MAX || info->lo_sizelimit > LLONG_MAX)
 982                return -EOVERFLOW;
 983
 984        lo->lo_offset = info->lo_offset;
 985        lo->lo_sizelimit = info->lo_sizelimit;
 986
 987        memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
 988        lo->lo_file_name[LO_NAME_SIZE-1] = 0;
 989        lo->lo_flags = info->lo_flags;
 990        return 0;
 991}
 992
 993static int loop_configure(struct loop_device *lo, blk_mode_t mode,
 994                          struct block_device *bdev,
 995                          const struct loop_config *config)
 996{
 997        struct file *file = fget(config->fd);
 998        struct inode *inode;
 999        struct address_space *mapping;
1000        int error;
1001        loff_t size;
1002        bool partscan;
1003        unsigned short bsize;
1004        bool is_loop;
1005
1006        if (!file)
1007                return -EBADF;
1008        is_loop = is_loop_device(file);
1009
1010        /* This is safe, since we have a reference from open(). */
1011        __module_get(THIS_MODULE);
1012
1013        /*
1014         * If we don't hold exclusive handle for the device, upgrade to it
1015         * here to avoid changing device under exclusive owner.
1016         */
1017        if (!(mode & BLK_OPEN_EXCL)) {
1018                error = bd_prepare_to_claim(bdev, loop_configure, NULL);
1019                if (error)
1020                        goto out_putf;
1021        }
1022
1023        error = loop_global_lock_killable(lo, is_loop);
1024        if (error)
1025                goto out_bdev;
1026
1027        error = -EBUSY;
1028        if (lo->lo_state != Lo_unbound)
1029                goto out_unlock;
1030
1031        error = loop_validate_file(file, bdev);
1032        if (error)
1033                goto out_unlock;
1034
1035        mapping = file->f_mapping;
1036        inode = mapping->host;
1037
1038        if ((config->info.lo_flags & ~LOOP_CONFIGURE_SETTABLE_FLAGS) != 0) {
1039                error = -EINVAL;
1040                goto out_unlock;
1041        }
1042
1043        if (config->block_size) {
1044                error = blk_validate_block_size(config->block_size);
1045                if (error)
1046                        goto out_unlock;
1047        }
1048
1049        error = loop_set_status_from_info(lo, &config->info);
1050        if (error)
1051                goto out_unlock;
1052
1053        if (!(file->f_mode & FMODE_WRITE) || !(mode & BLK_OPEN_WRITE) ||
1054            !file->f_op->write_iter)
1055                lo->lo_flags |= LO_FLAGS_READ_ONLY;
1056
1057        if (!lo->workqueue) {
1058                lo->workqueue = alloc_workqueue("loop%d",
1059                                                WQ_UNBOUND | WQ_FREEZABLE,
1060                                                0, lo->lo_number);
1061                if (!lo->workqueue) {
1062                        error = -ENOMEM;
1063                        goto out_unlock;
1064                }
1065        }
1066
1067        /* suppress uevents while reconfiguring the device */
1068        dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1);
1069
1070        disk_force_media_change(lo->lo_disk);
1071        set_disk_ro(lo->lo_disk, (lo->lo_flags & LO_FLAGS_READ_ONLY) != 0);
1072
1073        lo->use_dio = lo->lo_flags & LO_FLAGS_DIRECT_IO;
1074        lo->lo_device = bdev;
1075        lo->lo_backing_file = file;
1076        lo->old_gfp_mask = mapping_gfp_mask(mapping);
1077        mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
1078
1079        if (!(lo->lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
1080                blk_queue_write_cache(lo->lo_queue, true, false);
1081
1082        if (config->block_size)
1083                bsize = config->block_size;
1084        else if ((lo->lo_backing_file->f_flags & O_DIRECT) && inode->i_sb->s_bdev)
1085                /* In case of direct I/O, match underlying block size */
1086                bsize = bdev_logical_block_size(inode->i_sb->s_bdev);
1087        else
1088                bsize = 512;
1089
1090        blk_queue_logical_block_size(lo->lo_queue, bsize);
1091        blk_queue_physical_block_size(lo->lo_queue, bsize);
1092        blk_queue_io_min(lo->lo_queue, bsize);
1093
1094        loop_config_discard(lo);
1095        loop_update_rotational(lo);
1096        loop_update_dio(lo);
1097        loop_sysfs_init(lo);
1098
1099        size = get_loop_size(lo, file);
1100        loop_set_size(lo, size);
1101
1102        /* Order wrt reading lo_state in loop_validate_file(). */
1103        wmb();
1104
1105        lo->lo_state = Lo_bound;
1106        if (part_shift)
1107                lo->lo_flags |= LO_FLAGS_PARTSCAN;
1108        partscan = lo->lo_flags & LO_FLAGS_PARTSCAN;
1109        if (partscan)
1110                clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
1111
1112        /* enable and uncork uevent now that we are done */
1113        dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0);
1114
1115        loop_global_unlock(lo, is_loop);
1116        if (partscan)
1117                loop_reread_partitions(lo);
1118
1119        if (!(mode & BLK_OPEN_EXCL))
1120                bd_abort_claiming(bdev, loop_configure);
1121
1122        return 0;
1123
1124out_unlock:
1125        loop_global_unlock(lo, is_loop);
1126out_bdev:
1127        if (!(mode & BLK_OPEN_EXCL))
1128                bd_abort_claiming(bdev, loop_configure);
1129out_putf:
1130        fput(file);
1131        /* This is safe: open() is still holding a reference. */
1132        module_put(THIS_MODULE);
1133        return error;
1134}
1135
1136static void __loop_clr_fd(struct loop_device *lo, bool release)
1137{
1138        struct file *filp;
1139        gfp_t gfp = lo->old_gfp_mask;
1140
1141        if (test_bit(QUEUE_FLAG_WC, &lo->lo_queue->queue_flags))
1142                blk_queue_write_cache(lo->lo_queue, false, false);
1143
1144        /*
1145         * Freeze the request queue when unbinding on a live file descriptor and
1146         * thus an open device.  When called from ->release we are guaranteed
1147         * that there is no I/O in progress already.
1148         */
1149        if (!release)
1150                blk_mq_freeze_queue(lo->lo_queue);
1151
1152        spin_lock_irq(&lo->lo_lock);
1153        filp = lo->lo_backing_file;
1154        lo->lo_backing_file = NULL;
1155        spin_unlock_irq(&lo->lo_lock);
1156
1157        lo->lo_device = NULL;
1158        lo->lo_offset = 0;
1159        lo->lo_sizelimit = 0;
1160        memset(lo->lo_file_name, 0, LO_NAME_SIZE);
1161        blk_queue_logical_block_size(lo->lo_queue, 512);
1162        blk_queue_physical_block_size(lo->lo_queue, 512);
1163        blk_queue_io_min(lo->lo_queue, 512);
1164        invalidate_disk(lo->lo_disk);
1165        loop_sysfs_exit(lo);
1166        /* let user-space know about this change */
1167        kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE);
1168        mapping_set_gfp_mask(filp->f_mapping, gfp);
1169        /* This is safe: open() is still holding a reference. */
1170        module_put(THIS_MODULE);
1171        if (!release)
1172                blk_mq_unfreeze_queue(lo->lo_queue);
1173
1174        disk_force_media_change(lo->lo_disk);
1175
1176        if (lo->lo_flags & LO_FLAGS_PARTSCAN) {
1177                int err;
1178
1179                /*
1180                 * open_mutex has been held already in release path, so don't
1181                 * acquire it if this function is called in such case.
1182                 *
1183                 * If the reread partition isn't from release path, lo_refcnt
1184                 * must be at least one and it can only become zero when the
1185                 * current holder is released.
1186                 */
1187                if (!release)
1188                        mutex_lock(&lo->lo_disk->open_mutex);
1189                err = bdev_disk_changed(lo->lo_disk, false);
1190                if (!release)
1191                        mutex_unlock(&lo->lo_disk->open_mutex);
1192                if (err)
1193                        pr_warn("%s: partition scan of loop%d failed (rc=%d)\n",
1194                                __func__, lo->lo_number, err);
1195                /* Device is gone, no point in returning error */
1196        }
1197
1198        /*
1199         * lo->lo_state is set to Lo_unbound here after above partscan has
1200         * finished. There cannot be anybody else entering __loop_clr_fd() as
1201         * Lo_rundown state protects us from all the other places trying to
1202         * change the 'lo' device.
1203         */
1204        lo->lo_flags = 0;
1205        if (!part_shift)
1206                set_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
1207        mutex_lock(&lo->lo_mutex);
1208        lo->lo_state = Lo_unbound;
1209        mutex_unlock(&lo->lo_mutex);
1210
1211        /*
1212         * Need not hold lo_mutex to fput backing file. Calling fput holding
1213         * lo_mutex triggers a circular lock dependency possibility warning as
1214         * fput can take open_mutex which is usually taken before lo_mutex.
1215         */
1216        fput(filp);
1217}
1218
1219static int loop_clr_fd(struct loop_device *lo)
1220{
1221        int err;
1222
1223        /*
1224         * Since lo_ioctl() is called without locks held, it is possible that
1225         * loop_configure()/loop_change_fd() and loop_clr_fd() run in parallel.
1226         *
1227         * Therefore, use global lock when setting Lo_rundown state in order to
1228         * make sure that loop_validate_file() will fail if the "struct file"
1229         * which loop_configure()/loop_change_fd() found via fget() was this
1230         * loop device.
1231         */
1232        err = loop_global_lock_killable(lo, true);
1233        if (err)
1234                return err;
1235        if (lo->lo_state != Lo_bound) {
1236                loop_global_unlock(lo, true);
1237                return -ENXIO;
1238        }
1239        /*
1240         * If we've explicitly asked to tear down the loop device,
1241         * and it has an elevated reference count, set it for auto-teardown when
1242         * the last reference goes away. This stops $!~#$@ udev from
1243         * preventing teardown because it decided that it needs to run blkid on
1244         * the loopback device whenever they appear. xfstests is notorious for
1245         * failing tests because blkid via udev races with a losetup
1246         * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d
1247         * command to fail with EBUSY.
1248         */
1249        if (disk_openers(lo->lo_disk) > 1) {
1250                lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
1251                loop_global_unlock(lo, true);
1252                return 0;
1253        }
1254        lo->lo_state = Lo_rundown;
1255        loop_global_unlock(lo, true);
1256
1257        __loop_clr_fd(lo, false);
1258        return 0;
1259}
1260
1261static int
1262loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
1263{
1264        int err;
1265        int prev_lo_flags;
1266        bool partscan = false;
1267        bool size_changed = false;
1268
1269        err = mutex_lock_killable(&lo->lo_mutex);
1270        if (err)
1271                return err;
1272        if (lo->lo_state != Lo_bound) {
1273                err = -ENXIO;
1274                goto out_unlock;
1275        }
1276
1277        if (lo->lo_offset != info->lo_offset ||
1278            lo->lo_sizelimit != info->lo_sizelimit) {
1279                size_changed = true;
1280                sync_blockdev(lo->lo_device);
1281                invalidate_bdev(lo->lo_device);
1282        }
1283
1284        /* I/O need to be drained during transfer transition */
1285        blk_mq_freeze_queue(lo->lo_queue);
1286
1287        prev_lo_flags = lo->lo_flags;
1288
1289        err = loop_set_status_from_info(lo, info);
1290        if (err)
1291                goto out_unfreeze;
1292
1293        /* Mask out flags that can't be set using LOOP_SET_STATUS. */
1294        lo->lo_flags &= LOOP_SET_STATUS_SETTABLE_FLAGS;
1295        /* For those flags, use the previous values instead */
1296        lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_SETTABLE_FLAGS;
1297        /* For flags that can't be cleared, use previous values too */
1298        lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_CLEARABLE_FLAGS;
1299
1300        if (size_changed) {
1301                loff_t new_size = get_size(lo->lo_offset, lo->lo_sizelimit,
1302                                           lo->lo_backing_file);
1303                loop_set_size(lo, new_size);
1304        }
1305
1306        loop_config_discard(lo);
1307
1308        /* update dio if lo_offset or transfer is changed */
1309        __loop_update_dio(lo, lo->use_dio);
1310
1311out_unfreeze:
1312        blk_mq_unfreeze_queue(lo->lo_queue);
1313
1314        if (!err && (lo->lo_flags & LO_FLAGS_PARTSCAN) &&
1315             !(prev_lo_flags & LO_FLAGS_PARTSCAN)) {
1316                clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
1317                partscan = true;
1318        }
1319out_unlock:
1320        mutex_unlock(&lo->lo_mutex);
1321        if (partscan)
1322                loop_reread_partitions(lo);
1323
1324        return err;
1325}
1326
1327static int
1328loop_get_status(struct loop_device *lo, struct loop_info64 *info)
1329{
1330        struct path path;
1331        struct kstat stat;
1332        int ret;
1333
1334        ret = mutex_lock_killable(&lo->lo_mutex);
1335        if (ret)
1336                return ret;
1337        if (lo->lo_state != Lo_bound) {
1338                mutex_unlock(&lo->lo_mutex);
1339                return -ENXIO;
1340        }
1341
1342        memset(info, 0, sizeof(*info));
1343        info->lo_number = lo->lo_number;
1344        info->lo_offset = lo->lo_offset;
1345        info->lo_sizelimit = lo->lo_sizelimit;
1346        info->lo_flags = lo->lo_flags;
1347        memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
1348
1349        /* Drop lo_mutex while we call into the filesystem. */
1350        path = lo->lo_backing_file->f_path;
1351        path_get(&path);
1352        mutex_unlock(&lo->lo_mutex);
1353        ret = vfs_getattr(&path, &stat, STATX_INO, AT_STATX_SYNC_AS_STAT);
1354        if (!ret) {
1355                info->lo_device = huge_encode_dev(stat.dev);
1356                info->lo_inode = stat.ino;
1357                info->lo_rdevice = huge_encode_dev(stat.rdev);
1358        }
1359        path_put(&path);
1360        return ret;
1361}
1362
1363static void
1364loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1365{
1366        memset(info64, 0, sizeof(*info64));
1367        info64->lo_number = info->lo_number;
1368        info64->lo_device = info->lo_device;
1369        info64->lo_inode = info->lo_inode;
1370        info64->lo_rdevice = info->lo_rdevice;
1371        info64->lo_offset = info->lo_offset;
1372        info64->lo_sizelimit = 0;
1373        info64->lo_flags = info->lo_flags;
1374        memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1375}
1376
1377static int
1378loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1379{
1380        memset(info, 0, sizeof(*info));
1381        info->lo_number = info64->lo_number;
1382        info->lo_device = info64->lo_device;
1383        info->lo_inode = info64->lo_inode;
1384        info->lo_rdevice = info64->lo_rdevice;
1385        info->lo_offset = info64->lo_offset;
1386        info->lo_flags = info64->lo_flags;
1387        memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1388
1389        /* error in case values were truncated */
1390        if (info->lo_device != info64->lo_device ||
1391            info->lo_rdevice != info64->lo_rdevice ||
1392            info->lo_inode != info64->lo_inode ||
1393            info->lo_offset != info64->lo_offset)
1394                return -EOVERFLOW;
1395
1396        return 0;
1397}
1398
1399static int
1400loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1401{
1402        struct loop_info info;
1403        struct loop_info64 info64;
1404
1405        if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1406                return -EFAULT;
1407        loop_info64_from_old(&info, &info64);
1408        return loop_set_status(lo, &info64);
1409}
1410
1411static int
1412loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1413{
1414        struct loop_info64 info64;
1415
1416        if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1417                return -EFAULT;
1418        return loop_set_status(lo, &info64);
1419}
1420
1421static int
1422loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1423        struct loop_info info;
1424        struct loop_info64 info64;
1425        int err;
1426
1427        if (!arg)
1428                return -EINVAL;
1429        err = loop_get_status(lo, &info64);
1430        if (!err)
1431                err = loop_info64_to_old(&info64, &info);
1432        if (!err && copy_to_user(arg, &info, sizeof(info)))
1433                err = -EFAULT;
1434
1435        return err;
1436}
1437
1438static int
1439loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1440        struct loop_info64 info64;
1441        int err;
1442
1443        if (!arg)
1444                return -EINVAL;
1445        err = loop_get_status(lo, &info64);
1446        if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1447                err = -EFAULT;
1448
1449        return err;
1450}
1451
1452static int loop_set_capacity(struct loop_device *lo)
1453{
1454        loff_t size;
1455
1456        if (unlikely(lo->lo_state != Lo_bound))
1457                return -ENXIO;
1458
1459        size = get_loop_size(lo, lo->lo_backing_file);
1460        loop_set_size(lo, size);
1461
1462        return 0;
1463}
1464
1465static int loop_set_dio(struct loop_device *lo, unsigned long arg)
1466{
1467        int error = -ENXIO;
1468        if (lo->lo_state != Lo_bound)
1469                goto out;
1470
1471        __loop_update_dio(lo, !!arg);
1472        if (lo->use_dio == !!arg)
1473                return 0;
1474        error = -EINVAL;
1475 out:
1476        return error;
1477}
1478
1479static int loop_set_block_size(struct loop_device *lo, unsigned long arg)
1480{
1481        int err = 0;
1482
1483        if (lo->lo_state != Lo_bound)
1484                return -ENXIO;
1485
1486        err = blk_validate_block_size(arg);
1487        if (err)
1488                return err;
1489
1490        if (lo->lo_queue->limits.logical_block_size == arg)
1491                return 0;
1492
1493        sync_blockdev(lo->lo_device);
1494        invalidate_bdev(lo->lo_device);
1495
1496        blk_mq_freeze_queue(lo->lo_queue);
1497        blk_queue_logical_block_size(lo->lo_queue, arg);
1498        blk_queue_physical_block_size(lo->lo_queue, arg);
1499        blk_queue_io_min(lo->lo_queue, arg);
1500        loop_update_dio(lo);
1501        blk_mq_unfreeze_queue(lo->lo_queue);
1502
1503        return err;
1504}
1505
1506static int lo_simple_ioctl(struct loop_device *lo, unsigned int cmd,
1507                           unsigned long arg)
1508{
1509        int err;
1510
1511        err = mutex_lock_killable(&lo->lo_mutex);
1512        if (err)
1513                return err;
1514        switch (cmd) {
1515        case LOOP_SET_CAPACITY:
1516                err = loop_set_capacity(lo);
1517                break;
1518        case LOOP_SET_DIRECT_IO:
1519                err = loop_set_dio(lo, arg);
1520                break;
1521        case LOOP_SET_BLOCK_SIZE:
1522                err = loop_set_block_size(lo, arg);
1523                break;
1524        default:
1525                err = -EINVAL;
1526        }
1527        mutex_unlock(&lo->lo_mutex);
1528        return err;
1529}
1530
1531static int lo_ioctl(struct block_device *bdev, blk_mode_t mode,
1532        unsigned int cmd, unsigned long arg)
1533{
1534        struct loop_device *lo = bdev->bd_disk->private_data;
1535        void __user *argp = (void __user *) arg;
1536        int err;
1537
1538        switch (cmd) {
1539        case LOOP_SET_FD: {
1540                /*
1541                 * Legacy case - pass in a zeroed out struct loop_config with
1542                 * only the file descriptor set , which corresponds with the
1543                 * default parameters we'd have used otherwise.
1544                 */
1545                struct loop_config config;
1546
1547                memset(&config, 0, sizeof(config));
1548                config.fd = arg;
1549
1550                return loop_configure(lo, mode, bdev, &config);
1551        }
1552        case LOOP_CONFIGURE: {
1553                struct loop_config config;
1554
1555                if (copy_from_user(&config, argp, sizeof(config)))
1556                        return -EFAULT;
1557
1558                return loop_configure(lo, mode, bdev, &config);
1559        }
1560        case LOOP_CHANGE_FD:
1561                return loop_change_fd(lo, bdev, arg);
1562        case LOOP_CLR_FD:
1563                return loop_clr_fd(lo);
1564        case LOOP_SET_STATUS:
1565                err = -EPERM;
1566                if ((mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN))
1567                        err = loop_set_status_old(lo, argp);
1568                break;
1569        case LOOP_GET_STATUS:
1570                return loop_get_status_old(lo, argp);
1571        case LOOP_SET_STATUS64:
1572                err = -EPERM;
1573                if ((mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN))
1574                        err = loop_set_status64(lo, argp);
1575                break;
1576        case LOOP_GET_STATUS64:
1577                return loop_get_status64(lo, argp);
1578        case LOOP_SET_CAPACITY:
1579        case LOOP_SET_DIRECT_IO:
1580        case LOOP_SET_BLOCK_SIZE:
1581                if (!(mode & BLK_OPEN_WRITE) && !capable(CAP_SYS_ADMIN))
1582                        return -EPERM;
1583                fallthrough;
1584        default:
1585                err = lo_simple_ioctl(lo, cmd, arg);
1586                break;
1587        }
1588
1589        return err;
1590}
1591
1592#ifdef CONFIG_COMPAT
1593struct compat_loop_info {
1594        compat_int_t    lo_number;      /* ioctl r/o */
1595        compat_dev_t    lo_device;      /* ioctl r/o */
1596        compat_ulong_t  lo_inode;       /* ioctl r/o */
1597        compat_dev_t    lo_rdevice;     /* ioctl r/o */
1598        compat_int_t    lo_offset;
1599        compat_int_t    lo_encrypt_type;        /* obsolete, ignored */
1600        compat_int_t    lo_encrypt_key_size;    /* ioctl w/o */
1601        compat_int_t    lo_flags;       /* ioctl r/o */
1602        char            lo_name[LO_NAME_SIZE];
1603        unsigned char   lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
1604        compat_ulong_t  lo_init[2];
1605        char            reserved[4];
1606};
1607
1608/*
1609 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1610 * - noinlined to reduce stack space usage in main part of driver
1611 */
1612static noinline int
1613loop_info64_from_compat(const struct compat_loop_info __user *arg,
1614                        struct loop_info64 *info64)
1615{
1616        struct compat_loop_info info;
1617
1618        if (copy_from_user(&info, arg, sizeof(info)))
1619                return -EFAULT;
1620
1621        memset(info64, 0, sizeof(*info64));
1622        info64->lo_number = info.lo_number;
1623        info64->lo_device = info.lo_device;
1624        info64->lo_inode = info.lo_inode;
1625        info64->lo_rdevice = info.lo_rdevice;
1626        info64->lo_offset = info.lo_offset;
1627        info64->lo_sizelimit = 0;
1628        info64->lo_flags = info.lo_flags;
1629        memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
1630        return 0;
1631}
1632
1633/*
1634 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1635 * - noinlined to reduce stack space usage in main part of driver
1636 */
1637static noinline int
1638loop_info64_to_compat(const struct loop_info64 *info64,
1639                      struct compat_loop_info __user *arg)
1640{
1641        struct compat_loop_info info;
1642
1643        memset(&info, 0, sizeof(info));
1644        info.lo_number = info64->lo_number;
1645        info.lo_device = info64->lo_device;
1646        info.lo_inode = info64->lo_inode;
1647        info.lo_rdevice = info64->lo_rdevice;
1648        info.lo_offset = info64->lo_offset;
1649        info.lo_flags = info64->lo_flags;
1650        memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
1651
1652        /* error in case values were truncated */
1653        if (info.lo_device != info64->lo_device ||
1654            info.lo_rdevice != info64->lo_rdevice ||
1655            info.lo_inode != info64->lo_inode ||
1656            info.lo_offset != info64->lo_offset)
1657                return -EOVERFLOW;
1658
1659        if (copy_to_user(arg, &info, sizeof(info)))
1660                return -EFAULT;
1661        return 0;
1662}
1663
1664static int
1665loop_set_status_compat(struct loop_device *lo,
1666                       const struct compat_loop_info __user *arg)
1667{
1668        struct loop_info64 info64;
1669        int ret;
1670
1671        ret = loop_info64_from_compat(arg, &info64);
1672        if (ret < 0)
1673                return ret;
1674        return loop_set_status(lo, &info64);
1675}
1676
1677static int
1678loop_get_status_compat(struct loop_device *lo,
1679                       struct compat_loop_info __user *arg)
1680{
1681        struct loop_info64 info64;
1682        int err;
1683
1684        if (!arg)
1685                return -EINVAL;
1686        err = loop_get_status(lo, &info64);
1687        if (!err)
1688                err = loop_info64_to_compat(&info64, arg);
1689        return err;
1690}
1691
1692static int lo_compat_ioctl(struct block_device *bdev, blk_mode_t mode,
1693                           unsigned int cmd, unsigned long arg)
1694{
1695        struct loop_device *lo = bdev->bd_disk->private_data;
1696        int err;
1697
1698        switch(cmd) {
1699        case LOOP_SET_STATUS:
1700                err = loop_set_status_compat(lo,
1701                             (const struct compat_loop_info __user *)arg);
1702                break;
1703        case LOOP_GET_STATUS:
1704                err = loop_get_status_compat(lo,
1705                                     (struct compat_loop_info __user *)arg);
1706                break;
1707        case LOOP_SET_CAPACITY:
1708        case LOOP_CLR_FD:
1709        case LOOP_GET_STATUS64:
1710        case LOOP_SET_STATUS64:
1711        case LOOP_CONFIGURE:
1712                arg = (unsigned long) compat_ptr(arg);
1713                fallthrough;
1714        case LOOP_SET_FD:
1715        case LOOP_CHANGE_FD:
1716        case LOOP_SET_BLOCK_SIZE:
1717        case LOOP_SET_DIRECT_IO:
1718                err = lo_ioctl(bdev, mode, cmd, arg);
1719                break;
1720        default:
1721                err = -ENOIOCTLCMD;
1722                break;
1723        }
1724        return err;
1725}
1726#endif
1727
1728static void lo_release(struct gendisk *disk)
1729{
1730        struct loop_device *lo = disk->private_data;
1731
1732        if (disk_openers(disk) > 0)
1733                return;
1734
1735        mutex_lock(&lo->lo_mutex);
1736        if (lo->lo_state == Lo_bound && (lo->lo_flags & LO_FLAGS_AUTOCLEAR)) {
1737                lo->lo_state = Lo_rundown;
1738                mutex_unlock(&lo->lo_mutex);
1739                /*
1740                 * In autoclear mode, stop the loop thread
1741                 * and remove configuration after last close.
1742                 */
1743                __loop_clr_fd(lo, true);
1744                return;
1745        }
1746        mutex_unlock(&lo->lo_mutex);
1747}
1748
1749static void lo_free_disk(struct gendisk *disk)
1750{
1751        struct loop_device *lo = disk->private_data;
1752
1753        if (lo->workqueue)
1754                destroy_workqueue(lo->workqueue);
1755        loop_free_idle_workers(lo, true);
1756        timer_shutdown_sync(&lo->timer);
1757        mutex_destroy(&lo->lo_mutex);
1758        kfree(lo);
1759}
1760
1761static const struct block_device_operations lo_fops = {
1762        .owner =        THIS_MODULE,
1763        .release =      lo_release,
1764        .ioctl =        lo_ioctl,
1765#ifdef CONFIG_COMPAT
1766        .compat_ioctl = lo_compat_ioctl,
1767#endif
1768        .free_disk =    lo_free_disk,
1769};
1770
1771/*
1772 * And now the modules code and kernel interface.
1773 */
1774
1775/*
1776 * If max_loop is specified, create that many devices upfront.
1777 * This also becomes a hard limit. If max_loop is not specified,
1778 * the default isn't a hard limit (as before commit 85c50197716c
1779 * changed the default value from 0 for max_loop=0 reasons), just
1780 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
1781 * init time. Loop devices can be requested on-demand with the
1782 * /dev/loop-control interface, or be instantiated by accessing
1783 * a 'dead' device node.
1784 */
1785static int max_loop = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
1786
1787#ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD
1788static bool max_loop_specified;
1789
1790static int max_loop_param_set_int(const char *val,
1791                                  const struct kernel_param *kp)
1792{
1793        int ret;
1794
1795        ret = param_set_int(val, kp);
1796        if (ret < 0)
1797                return ret;
1798
1799        max_loop_specified = true;
1800        return 0;
1801}
1802
1803static const struct kernel_param_ops max_loop_param_ops = {
1804        .set = max_loop_param_set_int,
1805        .get = param_get_int,
1806};
1807
1808module_param_cb(max_loop, &max_loop_param_ops, &max_loop, 0444);
1809MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
1810#else
1811module_param(max_loop, int, 0444);
1812MODULE_PARM_DESC(max_loop, "Initial number of loop devices");
1813#endif
1814
1815module_param(max_part, int, 0444);
1816MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
1817
1818static int hw_queue_depth = LOOP_DEFAULT_HW_Q_DEPTH;
1819
1820static int loop_set_hw_queue_depth(const char *s, const struct kernel_param *p)
1821{
1822        int qd, ret;
1823
1824        ret = kstrtoint(s, 0, &qd);
1825        if (ret < 0)
1826                return ret;
1827        if (qd < 1)
1828                return -EINVAL;
1829        hw_queue_depth = qd;
1830        return 0;
1831}
1832
1833static const struct kernel_param_ops loop_hw_qdepth_param_ops = {
1834        .set    = loop_set_hw_queue_depth,
1835        .get    = param_get_int,
1836};
1837
1838device_param_cb(hw_queue_depth, &loop_hw_qdepth_param_ops, &hw_queue_depth, 0444);
1839MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: " __stringify(LOOP_DEFAULT_HW_Q_DEPTH));
1840
1841MODULE_LICENSE("GPL");
1842MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1843
1844static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx,
1845                const struct blk_mq_queue_data *bd)
1846{
1847        struct request *rq = bd->rq;
1848        struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
1849        struct loop_device *lo = rq->q->queuedata;
1850
1851        blk_mq_start_request(rq);
1852
1853        if (lo->lo_state != Lo_bound)
1854                return BLK_STS_IOERR;
1855
1856        switch (req_op(rq)) {
1857        case REQ_OP_FLUSH:
1858        case REQ_OP_DISCARD:
1859        case REQ_OP_WRITE_ZEROES:
1860                cmd->use_aio = false;
1861                break;
1862        default:
1863                cmd->use_aio = lo->use_dio;
1864                break;
1865        }
1866
1867        /* always use the first bio's css */
1868        cmd->blkcg_css = NULL;
1869        cmd->memcg_css = NULL;
1870#ifdef CONFIG_BLK_CGROUP
1871        if (rq->bio) {
1872                cmd->blkcg_css = bio_blkcg_css(rq->bio);
1873#ifdef CONFIG_MEMCG
1874                if (cmd->blkcg_css) {
1875                        cmd->memcg_css =
1876                                cgroup_get_e_css(cmd->blkcg_css->cgroup,
1877                                                &memory_cgrp_subsys);
1878                }
1879#endif
1880        }
1881#endif
1882        loop_queue_work(lo, cmd);
1883
1884        return BLK_STS_OK;
1885}
1886
1887static void loop_handle_cmd(struct loop_cmd *cmd)
1888{
1889        struct cgroup_subsys_state *cmd_blkcg_css = cmd->blkcg_css;
1890        struct cgroup_subsys_state *cmd_memcg_css = cmd->memcg_css;
1891        struct request *rq = blk_mq_rq_from_pdu(cmd);
1892        const bool write = op_is_write(req_op(rq));
1893        struct loop_device *lo = rq->q->queuedata;
1894        int ret = 0;
1895        struct mem_cgroup *old_memcg = NULL;
1896        const bool use_aio = cmd->use_aio;
1897
1898        if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) {
1899                ret = -EIO;
1900                goto failed;
1901        }
1902
1903        if (cmd_blkcg_css)
1904                kthread_associate_blkcg(cmd_blkcg_css);
1905        if (cmd_memcg_css)
1906                old_memcg = set_active_memcg(
1907                        mem_cgroup_from_css(cmd_memcg_css));
1908
1909        /*
1910         * do_req_filebacked() may call blk_mq_complete_request() synchronously
1911         * or asynchronously if using aio. Hence, do not touch 'cmd' after
1912         * do_req_filebacked() has returned unless we are sure that 'cmd' has
1913         * not yet been completed.
1914         */
1915        ret = do_req_filebacked(lo, rq);
1916
1917        if (cmd_blkcg_css)
1918                kthread_associate_blkcg(NULL);
1919
1920        if (cmd_memcg_css) {
1921                set_active_memcg(old_memcg);
1922                css_put(cmd_memcg_css);
1923        }
1924 failed:
1925        /* complete non-aio request */
1926        if (!use_aio || ret) {
1927                if (ret == -EOPNOTSUPP)
1928                        cmd->ret = ret;
1929                else
1930                        cmd->ret = ret ? -EIO : 0;
1931                if (likely(!blk_should_fake_timeout(rq->q)))
1932                        blk_mq_complete_request(rq);
1933        }
1934}
1935
1936static void loop_process_work(struct loop_worker *worker,
1937                        struct list_head *cmd_list, struct loop_device *lo)
1938{
1939        int orig_flags = current->flags;
1940        struct loop_cmd *cmd;
1941
1942        current->flags |= PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO;
1943        spin_lock_irq(&lo->lo_work_lock);
1944        while (!list_empty(cmd_list)) {
1945                cmd = container_of(
1946                        cmd_list->next, struct loop_cmd, list_entry);
1947                list_del(cmd_list->next);
1948                spin_unlock_irq(&lo->lo_work_lock);
1949
1950                loop_handle_cmd(cmd);
1951                cond_resched();
1952
1953                spin_lock_irq(&lo->lo_work_lock);
1954        }
1955
1956        /*
1957         * We only add to the idle list if there are no pending cmds
1958         * *and* the worker will not run again which ensures that it
1959         * is safe to free any worker on the idle list
1960         */
1961        if (worker && !work_pending(&worker->work)) {
1962                worker->last_ran_at = jiffies;
1963                list_add_tail(&worker->idle_list, &lo->idle_worker_list);
1964                loop_set_timer(lo);
1965        }
1966        spin_unlock_irq(&lo->lo_work_lock);
1967        current->flags = orig_flags;
1968}
1969
1970static void loop_workfn(struct work_struct *work)
1971{
1972        struct loop_worker *worker =
1973                container_of(work, struct loop_worker, work);
1974        loop_process_work(worker, &worker->cmd_list, worker->lo);
1975}
1976
1977static void loop_rootcg_workfn(struct work_struct *work)
1978{
1979        struct loop_device *lo =
1980                container_of(work, struct loop_device, rootcg_work);
1981        loop_process_work(NULL, &lo->rootcg_cmd_list, lo);
1982}
1983
1984static const struct blk_mq_ops loop_mq_ops = {
1985        .queue_rq       = loop_queue_rq,
1986        .complete       = lo_complete_rq,
1987};
1988
1989static int loop_add(int i)
1990{
1991        struct loop_device *lo;
1992        struct gendisk *disk;
1993        int err;
1994
1995        err = -ENOMEM;
1996        lo = kzalloc(sizeof(*lo), GFP_KERNEL);
1997        if (!lo)
1998                goto out;
1999        lo->worker_tree = RB_ROOT;
2000        INIT_LIST_HEAD(&lo->idle_worker_list);
2001        timer_setup(&lo->timer, loop_free_idle_workers_timer, TIMER_DEFERRABLE);
2002        lo->lo_state = Lo_unbound;
2003
2004        err = mutex_lock_killable(&loop_ctl_mutex);
2005        if (err)
2006                goto out_free_dev;
2007
2008        /* allocate id, if @id >= 0, we're requesting that specific id */
2009        if (i >= 0) {
2010                err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL);
2011                if (err == -ENOSPC)
2012                        err = -EEXIST;
2013        } else {
2014                err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL);
2015        }
2016        mutex_unlock(&loop_ctl_mutex);
2017        if (err < 0)
2018                goto out_free_dev;
2019        i = err;
2020
2021        lo->tag_set.ops = &loop_mq_ops;
2022        lo->tag_set.nr_hw_queues = 1;
2023        lo->tag_set.queue_depth = hw_queue_depth;
2024        lo->tag_set.numa_node = NUMA_NO_NODE;
2025        lo->tag_set.cmd_size = sizeof(struct loop_cmd);
2026        lo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING |
2027                BLK_MQ_F_NO_SCHED_BY_DEFAULT;
2028        lo->tag_set.driver_data = lo;
2029
2030        err = blk_mq_alloc_tag_set(&lo->tag_set);
2031        if (err)
2032                goto out_free_idr;
2033
2034        disk = lo->lo_disk = blk_mq_alloc_disk(&lo->tag_set, lo);
2035        if (IS_ERR(disk)) {
2036                err = PTR_ERR(disk);
2037                goto out_cleanup_tags;
2038        }
2039        lo->lo_queue = lo->lo_disk->queue;
2040
2041        blk_queue_max_hw_sectors(lo->lo_queue, BLK_DEF_MAX_SECTORS);
2042
2043        /*
2044         * By default, we do buffer IO, so it doesn't make sense to enable
2045         * merge because the I/O submitted to backing file is handled page by
2046         * page. For directio mode, merge does help to dispatch bigger request
2047         * to underlayer disk. We will enable merge once directio is enabled.
2048         */
2049        blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue);
2050
2051        /*
2052         * Disable partition scanning by default. The in-kernel partition
2053         * scanning can be requested individually per-device during its
2054         * setup. Userspace can always add and remove partitions from all
2055         * devices. The needed partition minors are allocated from the
2056         * extended minor space, the main loop device numbers will continue
2057         * to match the loop minors, regardless of the number of partitions
2058         * used.
2059         *
2060         * If max_part is given, partition scanning is globally enabled for
2061         * all loop devices. The minors for the main loop devices will be
2062         * multiples of max_part.
2063         *
2064         * Note: Global-for-all-devices, set-only-at-init, read-only module
2065         * parameteters like 'max_loop' and 'max_part' make things needlessly
2066         * complicated, are too static, inflexible and may surprise
2067         * userspace tools. Parameters like this in general should be avoided.
2068         */
2069        if (!part_shift)
2070                set_bit(GD_SUPPRESS_PART_SCAN, &disk->state);
2071        mutex_init(&lo->lo_mutex);
2072        lo->lo_number           = i;
2073        spin_lock_init(&lo->lo_lock);
2074        spin_lock_init(&lo->lo_work_lock);
2075        INIT_WORK(&lo->rootcg_work, loop_rootcg_workfn);
2076        INIT_LIST_HEAD(&lo->rootcg_cmd_list);
2077        disk->major             = LOOP_MAJOR;
2078        disk->first_minor       = i << part_shift;
2079        disk->minors            = 1 << part_shift;
2080        disk->fops              = &lo_fops;
2081        disk->private_data      = lo;
2082        disk->queue             = lo->lo_queue;
2083        disk->events            = DISK_EVENT_MEDIA_CHANGE;
2084        disk->event_flags       = DISK_EVENT_FLAG_UEVENT;
2085        sprintf(disk->disk_name, "loop%d", i);
2086        /* Make this loop device reachable from pathname. */
2087        err = add_disk(disk);
2088        if (err)
2089                goto out_cleanup_disk;
2090
2091        /* Show this loop device. */
2092        mutex_lock(&loop_ctl_mutex);
2093        lo->idr_visible = true;
2094        mutex_unlock(&loop_ctl_mutex);
2095
2096        return i;
2097
2098out_cleanup_disk:
2099        put_disk(disk);
2100out_cleanup_tags:
2101        blk_mq_free_tag_set(&lo->tag_set);
2102out_free_idr:
2103        mutex_lock(&loop_ctl_mutex);
2104        idr_remove(&loop_index_idr, i);
2105        mutex_unlock(&loop_ctl_mutex);
2106out_free_dev:
2107        kfree(lo);
2108out:
2109        return err;
2110}
2111
2112static void loop_remove(struct loop_device *lo)
2113{
2114        /* Make this loop device unreachable from pathname. */
2115        del_gendisk(lo->lo_disk);
2116        blk_mq_free_tag_set(&lo->tag_set);
2117
2118        mutex_lock(&loop_ctl_mutex);
2119        idr_remove(&loop_index_idr, lo->lo_number);
2120        mutex_unlock(&loop_ctl_mutex);
2121
2122        put_disk(lo->lo_disk);
2123}
2124
2125#ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD
2126static void loop_probe(dev_t dev)
2127{
2128        int idx = MINOR(dev) >> part_shift;
2129
2130        if (max_loop_specified && max_loop && idx >= max_loop)
2131                return;
2132        loop_add(idx);
2133}
2134#else
2135#define loop_probe NULL
2136#endif /* !CONFIG_BLOCK_LEGACY_AUTOLOAD */
2137
2138static int loop_control_remove(int idx)
2139{
2140        struct loop_device *lo;
2141        int ret;
2142
2143        if (idx < 0) {
2144                pr_warn_once("deleting an unspecified loop device is not supported.\n");
2145                return -EINVAL;
2146        }
2147                
2148        /* Hide this loop device for serialization. */
2149        ret = mutex_lock_killable(&loop_ctl_mutex);
2150        if (ret)
2151                return ret;
2152        lo = idr_find(&loop_index_idr, idx);
2153        if (!lo || !lo->idr_visible)
2154                ret = -ENODEV;
2155        else
2156                lo->idr_visible = false;
2157        mutex_unlock(&loop_ctl_mutex);
2158        if (ret)
2159                return ret;
2160
2161        /* Check whether this loop device can be removed. */
2162        ret = mutex_lock_killable(&lo->lo_mutex);
2163        if (ret)
2164                goto mark_visible;
2165        if (lo->lo_state != Lo_unbound || disk_openers(lo->lo_disk) > 0) {
2166                mutex_unlock(&lo->lo_mutex);
2167                ret = -EBUSY;
2168                goto mark_visible;
2169        }
2170        /* Mark this loop device as no more bound, but not quite unbound yet */
2171        lo->lo_state = Lo_deleting;
2172        mutex_unlock(&lo->lo_mutex);
2173
2174        loop_remove(lo);
2175        return 0;
2176
2177mark_visible:
2178        /* Show this loop device again. */
2179        mutex_lock(&loop_ctl_mutex);
2180        lo->idr_visible = true;
2181        mutex_unlock(&loop_ctl_mutex);
2182        return ret;
2183}
2184
2185static int loop_control_get_free(int idx)
2186{
2187        struct loop_device *lo;
2188        int id, ret;
2189
2190        ret = mutex_lock_killable(&loop_ctl_mutex);
2191        if (ret)
2192                return ret;
2193        idr_for_each_entry(&loop_index_idr, lo, id) {
2194                /* Hitting a race results in creating a new loop device which is harmless. */
2195                if (lo->idr_visible && data_race(lo->lo_state) == Lo_unbound)
2196                        goto found;
2197        }
2198        mutex_unlock(&loop_ctl_mutex);
2199        return loop_add(-1);
2200found:
2201        mutex_unlock(&loop_ctl_mutex);
2202        return id;
2203}
2204
2205static long loop_control_ioctl(struct file *file, unsigned int cmd,
2206                               unsigned long parm)
2207{
2208        switch (cmd) {
2209        case LOOP_CTL_ADD:
2210                return loop_add(parm);
2211        case LOOP_CTL_REMOVE:
2212                return loop_control_remove(parm);
2213        case LOOP_CTL_GET_FREE:
2214                return loop_control_get_free(parm);
2215        default:
2216                return -ENOSYS;
2217        }
2218}
2219
2220static const struct file_operations loop_ctl_fops = {
2221        .open           = nonseekable_open,
2222        .unlocked_ioctl = loop_control_ioctl,
2223        .compat_ioctl   = loop_control_ioctl,
2224        .owner          = THIS_MODULE,
2225        .llseek         = noop_llseek,
2226};
2227
2228static struct miscdevice loop_misc = {
2229        .minor          = LOOP_CTRL_MINOR,
2230        .name           = "loop-control",
2231        .fops           = &loop_ctl_fops,
2232};
2233
2234MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
2235MODULE_ALIAS("devname:loop-control");
2236
2237static int __init loop_init(void)
2238{
2239        int i;
2240        int err;
2241
2242        part_shift = 0;
2243        if (max_part > 0) {
2244                part_shift = fls(max_part);
2245
2246                /*
2247                 * Adjust max_part according to part_shift as it is exported
2248                 * to user space so that user can decide correct minor number
2249                 * if [s]he want to create more devices.
2250                 *
2251                 * Note that -1 is required because partition 0 is reserved
2252                 * for the whole disk.
2253                 */
2254                max_part = (1UL << part_shift) - 1;
2255        }
2256
2257        if ((1UL << part_shift) > DISK_MAX_PARTS) {
2258                err = -EINVAL;
2259                goto err_out;
2260        }
2261
2262        if (max_loop > 1UL << (MINORBITS - part_shift)) {
2263                err = -EINVAL;
2264                goto err_out;
2265        }
2266
2267        err = misc_register(&loop_misc);
2268        if (err < 0)
2269                goto err_out;
2270
2271
2272        if (__register_blkdev(LOOP_MAJOR, "loop", loop_probe)) {
2273                err = -EIO;
2274                goto misc_out;
2275        }
2276
2277        /* pre-create number of devices given by config or max_loop */
2278        for (i = 0; i < max_loop; i++)
2279                loop_add(i);
2280
2281        printk(KERN_INFO "loop: module loaded\n");
2282        return 0;
2283
2284misc_out:
2285        misc_deregister(&loop_misc);
2286err_out:
2287        return err;
2288}
2289
2290static void __exit loop_exit(void)
2291{
2292        struct loop_device *lo;
2293        int id;
2294
2295        unregister_blkdev(LOOP_MAJOR, "loop");
2296        misc_deregister(&loop_misc);
2297
2298        /*
2299         * There is no need to use loop_ctl_mutex here, for nobody else can
2300         * access loop_index_idr when this module is unloading (unless forced
2301         * module unloading is requested). If this is not a clean unloading,
2302         * we have no means to avoid kernel crash.
2303         */
2304        idr_for_each_entry(&loop_index_idr, lo, id)
2305                loop_remove(lo);
2306
2307        idr_destroy(&loop_index_idr);
2308}
2309
2310module_init(loop_init);
2311module_exit(loop_exit);
2312
2313#ifndef MODULE
2314static int __init max_loop_setup(char *str)
2315{
2316        max_loop = simple_strtol(str, NULL, 0);
2317#ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD
2318        max_loop_specified = true;
2319#endif
2320        return 1;
2321}
2322
2323__setup("max_loop=", max_loop_setup);
2324#endif
2325