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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * Copyright 1993 by Theodore Ts'o.
- */
- #include <linux/module.h>
- #include <linux/moduleparam.h>
- #include <linux/sched.h>
- #include <linux/fs.h>
- #include <linux/pagemap.h>
- #include <linux/file.h>
- #include <linux/stat.h>
- #include <linux/errno.h>
- #include <linux/major.h>
- #include <linux/wait.h>
- #include <linux/blkpg.h>
- #include <linux/init.h>
- #include <linux/swap.h>
- #include <linux/slab.h>
- #include <linux/compat.h>
- #include <linux/suspend.h>
- #include <linux/freezer.h>
- #include <linux/mutex.h>
- #include <linux/writeback.h>
- #include <linux/completion.h>
- #include <linux/highmem.h>
- #include <linux/splice.h>
- #include <linux/sysfs.h>
- #include <linux/miscdevice.h>
- #include <linux/falloc.h>
- #include <linux/uio.h>
- #include <linux/ioprio.h>
- #include <linux/blk-cgroup.h>
- #include <linux/sched/mm.h>
- #include <linux/statfs.h>
- #include <linux/uaccess.h>
- #include <linux/blk-mq.h>
- #include <linux/spinlock.h>
- #include <uapi/linux/loop.h>
- /* Possible states of device */
- enum {
- Lo_unbound,
- Lo_bound,
- Lo_rundown,
- Lo_deleting,
- };
- struct loop_func_table;
- struct loop_device {
- int lo_number;
- loff_t lo_offset;
- loff_t lo_sizelimit;
- int lo_flags;
- char lo_file_name[LO_NAME_SIZE];
- struct file * lo_backing_file;
- struct block_device *lo_device;
- gfp_t old_gfp_mask;
- spinlock_t lo_lock;
- int lo_state;
- spinlock_t lo_work_lock;
- struct workqueue_struct *workqueue;
- struct work_struct rootcg_work;
- struct list_head rootcg_cmd_list;
- struct list_head idle_worker_list;
- struct rb_root worker_tree;
- struct timer_list timer;
- bool use_dio;
- bool sysfs_inited;
- struct request_queue *lo_queue;
- struct blk_mq_tag_set tag_set;
- struct gendisk *lo_disk;
- struct mutex lo_mutex;
- bool idr_visible;
- };
- struct loop_cmd {
- struct list_head list_entry;
- bool use_aio; /* use AIO interface to handle I/O */
- atomic_t ref; /* only for aio */
- long ret;
- struct kiocb iocb;
- struct bio_vec *bvec;
- struct cgroup_subsys_state *blkcg_css;
- struct cgroup_subsys_state *memcg_css;
- };
- #define LOOP_IDLE_WORKER_TIMEOUT (60 * HZ)
- #define LOOP_DEFAULT_HW_Q_DEPTH (128)
- static DEFINE_IDR(loop_index_idr);
- static DEFINE_MUTEX(loop_ctl_mutex);
- static DEFINE_MUTEX(loop_validate_mutex);
- /**
- * loop_global_lock_killable() - take locks for safe loop_validate_file() test
- *
- * @lo: struct loop_device
- * @global: true if @lo is about to bind another "struct loop_device", false otherwise
- *
- * Returns 0 on success, -EINTR otherwise.
- *
- * Since loop_validate_file() traverses on other "struct loop_device" if
- * is_loop_device() is true, we need a global lock for serializing concurrent
- * loop_configure()/loop_change_fd()/__loop_clr_fd() calls.
- */
- static int loop_global_lock_killable(struct loop_device *lo, bool global)
- {
- int err;
- if (global) {
- err = mutex_lock_killable(&loop_validate_mutex);
- if (err)
- return err;
- }
- err = mutex_lock_killable(&lo->lo_mutex);
- if (err && global)
- mutex_unlock(&loop_validate_mutex);
- return err;
- }
- /**
- * loop_global_unlock() - release locks taken by loop_global_lock_killable()
- *
- * @lo: struct loop_device
- * @global: true if @lo was about to bind another "struct loop_device", false otherwise
- */
- static void loop_global_unlock(struct loop_device *lo, bool global)
- {
- mutex_unlock(&lo->lo_mutex);
- if (global)
- mutex_unlock(&loop_validate_mutex);
- }
- static int max_part;
- static int part_shift;
- static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file)
- {
- loff_t loopsize;
- /* Compute loopsize in bytes */
- loopsize = i_size_read(file->f_mapping->host);
- if (offset > 0)
- loopsize -= offset;
- /* offset is beyond i_size, weird but possible */
- if (loopsize < 0)
- return 0;
- if (sizelimit > 0 && sizelimit < loopsize)
- loopsize = sizelimit;
- /*
- * Unfortunately, if we want to do I/O on the device,
- * the number of 512-byte sectors has to fit into a sector_t.
- */
- return loopsize >> 9;
- }
- static loff_t get_loop_size(struct loop_device *lo, struct file *file)
- {
- return get_size(lo->lo_offset, lo->lo_sizelimit, file);
- }
- static void __loop_update_dio(struct loop_device *lo, bool dio)
- {
- struct file *file = lo->lo_backing_file;
- struct address_space *mapping = file->f_mapping;
- struct inode *inode = mapping->host;
- unsigned short sb_bsize = 0;
- unsigned dio_align = 0;
- bool use_dio;
- if (inode->i_sb->s_bdev) {
- sb_bsize = bdev_logical_block_size(inode->i_sb->s_bdev);
- dio_align = sb_bsize - 1;
- }
- /*
- * We support direct I/O only if lo_offset is aligned with the
- * logical I/O size of backing device, and the logical block
- * size of loop is bigger than the backing device's.
- *
- * TODO: the above condition may be loosed in the future, and
- * direct I/O may be switched runtime at that time because most
- * of requests in sane applications should be PAGE_SIZE aligned
- */
- if (dio) {
- if (queue_logical_block_size(lo->lo_queue) >= sb_bsize &&
- !(lo->lo_offset & dio_align) &&
- (file->f_mode & FMODE_CAN_ODIRECT))
- use_dio = true;
- else
- use_dio = false;
- } else {
- use_dio = false;
- }
- if (lo->use_dio == use_dio)
- return;
- /* flush dirty pages before changing direct IO */
- vfs_fsync(file, 0);
- /*
- * The flag of LO_FLAGS_DIRECT_IO is handled similarly with
- * LO_FLAGS_READ_ONLY, both are set from kernel, and losetup
- * will get updated by ioctl(LOOP_GET_STATUS)
- */
- if (lo->lo_state == Lo_bound)
- blk_mq_freeze_queue(lo->lo_queue);
- lo->use_dio = use_dio;
- if (use_dio) {
- blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, lo->lo_queue);
- lo->lo_flags |= LO_FLAGS_DIRECT_IO;
- } else {
- blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue);
- lo->lo_flags &= ~LO_FLAGS_DIRECT_IO;
- }
- if (lo->lo_state == Lo_bound)
- blk_mq_unfreeze_queue(lo->lo_queue);
- }
- /**
- * loop_set_size() - sets device size and notifies userspace
- * @lo: struct loop_device to set the size for
- * @size: new size of the loop device
- *
- * Callers must validate that the size passed into this function fits into
- * a sector_t, eg using loop_validate_size()
- */
- static void loop_set_size(struct loop_device *lo, loff_t size)
- {
- if (!set_capacity_and_notify(lo->lo_disk, size))
- kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE);
- }
- static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos)
- {
- struct iov_iter i;
- ssize_t bw;
- iov_iter_bvec(&i, ITER_SOURCE, bvec, 1, bvec->bv_len);
- file_start_write(file);
- bw = vfs_iter_write(file, &i, ppos, 0);
- file_end_write(file);
- if (likely(bw == bvec->bv_len))
- return 0;
- printk_ratelimited(KERN_ERR
- "loop: Write error at byte offset %llu, length %i.\n",
- (unsigned long long)*ppos, bvec->bv_len);
- if (bw >= 0)
- bw = -EIO;
- return bw;
- }
- static int lo_write_simple(struct loop_device *lo, struct request *rq,
- loff_t pos)
- {
- struct bio_vec bvec;
- struct req_iterator iter;
- int ret = 0;
- rq_for_each_segment(bvec, rq, iter) {
- ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos);
- if (ret < 0)
- break;
- cond_resched();
- }
- return ret;
- }
- static int lo_read_simple(struct loop_device *lo, struct request *rq,
- loff_t pos)
- {
- struct bio_vec bvec;
- struct req_iterator iter;
- struct iov_iter i;
- ssize_t len;
- rq_for_each_segment(bvec, rq, iter) {
- iov_iter_bvec(&i, ITER_DEST, &bvec, 1, bvec.bv_len);
- len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0);
- if (len < 0)
- return len;
- flush_dcache_page(bvec.bv_page);
- if (len != bvec.bv_len) {
- struct bio *bio;
- __rq_for_each_bio(bio, rq)
- zero_fill_bio(bio);
- break;
- }
- cond_resched();
- }
- return 0;
- }
- static int lo_fallocate(struct loop_device *lo, struct request *rq, loff_t pos,
- int mode)
- {
- /*
- * We use fallocate to manipulate the space mappings used by the image
- * a.k.a. discard/zerorange.
- */
- struct file *file = lo->lo_backing_file;
- int ret;
- mode |= FALLOC_FL_KEEP_SIZE;
- if (!bdev_max_discard_sectors(lo->lo_device))
- return -EOPNOTSUPP;
- ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq));
- if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP))
- return -EIO;
- return ret;
- }
- static int lo_req_flush(struct loop_device *lo, struct request *rq)
- {
- int ret = vfs_fsync(lo->lo_backing_file, 0);
- if (unlikely(ret && ret != -EINVAL))
- ret = -EIO;
- return ret;
- }
- static void lo_complete_rq(struct request *rq)
- {
- struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
- blk_status_t ret = BLK_STS_OK;
- if (!cmd->use_aio || cmd->ret < 0 || cmd->ret == blk_rq_bytes(rq) ||
- req_op(rq) != REQ_OP_READ) {
- if (cmd->ret < 0)
- ret = errno_to_blk_status(cmd->ret);
- goto end_io;
- }
- /*
- * Short READ - if we got some data, advance our request and
- * retry it. If we got no data, end the rest with EIO.
- */
- if (cmd->ret) {
- blk_update_request(rq, BLK_STS_OK, cmd->ret);
- cmd->ret = 0;
- blk_mq_requeue_request(rq, true);
- } else {
- if (cmd->use_aio) {
- struct bio *bio = rq->bio;
- while (bio) {
- zero_fill_bio(bio);
- bio = bio->bi_next;
- }
- }
- ret = BLK_STS_IOERR;
- end_io:
- blk_mq_end_request(rq, ret);
- }
- }
- static void lo_rw_aio_do_completion(struct loop_cmd *cmd)
- {
- struct request *rq = blk_mq_rq_from_pdu(cmd);
- if (!atomic_dec_and_test(&cmd->ref))
- return;
- kfree(cmd->bvec);
- cmd->bvec = NULL;
- if (likely(!blk_should_fake_timeout(rq->q)))
- blk_mq_complete_request(rq);
- }
- static void lo_rw_aio_complete(struct kiocb *iocb, long ret)
- {
- struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb);
- cmd->ret = ret;
- lo_rw_aio_do_completion(cmd);
- }
- static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
- loff_t pos, int rw)
- {
- struct iov_iter iter;
- struct req_iterator rq_iter;
- struct bio_vec *bvec;
- struct request *rq = blk_mq_rq_from_pdu(cmd);
- struct bio *bio = rq->bio;
- struct file *file = lo->lo_backing_file;
- struct bio_vec tmp;
- unsigned int offset;
- int nr_bvec = 0;
- int ret;
- rq_for_each_bvec(tmp, rq, rq_iter)
- nr_bvec++;
- if (rq->bio != rq->biotail) {
- bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec),
- GFP_NOIO);
- if (!bvec)
- return -EIO;
- cmd->bvec = bvec;
- /*
- * The bios of the request may be started from the middle of
- * the 'bvec' because of bio splitting, so we can't directly
- * copy bio->bi_iov_vec to new bvec. The rq_for_each_bvec
- * API will take care of all details for us.
- */
- rq_for_each_bvec(tmp, rq, rq_iter) {
- *bvec = tmp;
- bvec++;
- }
- bvec = cmd->bvec;
- offset = 0;
- } else {
- /*
- * Same here, this bio may be started from the middle of the
- * 'bvec' because of bio splitting, so offset from the bvec
- * must be passed to iov iterator
- */
- offset = bio->bi_iter.bi_bvec_done;
- bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
- }
- atomic_set(&cmd->ref, 2);
- iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq));
- iter.iov_offset = offset;
- cmd->iocb.ki_pos = pos;
- cmd->iocb.ki_filp = file;
- cmd->iocb.ki_complete = lo_rw_aio_complete;
- cmd->iocb.ki_flags = IOCB_DIRECT;
- cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
- if (rw == ITER_SOURCE)
- ret = call_write_iter(file, &cmd->iocb, &iter);
- else
- ret = call_read_iter(file, &cmd->iocb, &iter);
- lo_rw_aio_do_completion(cmd);
- if (ret != -EIOCBQUEUED)
- lo_rw_aio_complete(&cmd->iocb, ret);
- return 0;
- }
- static int do_req_filebacked(struct loop_device *lo, struct request *rq)
- {
- struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
- loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;
- /*
- * lo_write_simple and lo_read_simple should have been covered
- * by io submit style function like lo_rw_aio(), one blocker
- * is that lo_read_simple() need to call flush_dcache_page after
- * the page is written from kernel, and it isn't easy to handle
- * this in io submit style function which submits all segments
- * of the req at one time. And direct read IO doesn't need to
- * run flush_dcache_page().
- */
- switch (req_op(rq)) {
- case REQ_OP_FLUSH:
- return lo_req_flush(lo, rq);
- case REQ_OP_WRITE_ZEROES:
- /*
- * If the caller doesn't want deallocation, call zeroout to
- * write zeroes the range. Otherwise, punch them out.
- */
- return lo_fallocate(lo, rq, pos,
- (rq->cmd_flags & REQ_NOUNMAP) ?
- FALLOC_FL_ZERO_RANGE :
- FALLOC_FL_PUNCH_HOLE);
- case REQ_OP_DISCARD:
- return lo_fallocate(lo, rq, pos, FALLOC_FL_PUNCH_HOLE);
- case REQ_OP_WRITE:
- if (cmd->use_aio)
- return lo_rw_aio(lo, cmd, pos, ITER_SOURCE);
- else
- return lo_write_simple(lo, rq, pos);
- case REQ_OP_READ:
- if (cmd->use_aio)
- return lo_rw_aio(lo, cmd, pos, ITER_DEST);
- else
- return lo_read_simple(lo, rq, pos);
- default:
- WARN_ON_ONCE(1);
- return -EIO;
- }
- }
- static inline void loop_update_dio(struct loop_device *lo)
- {
- __loop_update_dio(lo, (lo->lo_backing_file->f_flags & O_DIRECT) |
- lo->use_dio);
- }
- static void loop_reread_partitions(struct loop_device *lo)
- {
- int rc;
- mutex_lock(&lo->lo_disk->open_mutex);
- rc = bdev_disk_changed(lo->lo_disk, false);
- mutex_unlock(&lo->lo_disk->open_mutex);
- if (rc)
- pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n",
- __func__, lo->lo_number, lo->lo_file_name, rc);
- }
- static inline int is_loop_device(struct file *file)
- {
- struct inode *i = file->f_mapping->host;
- return i && S_ISBLK(i->i_mode) && imajor(i) == LOOP_MAJOR;
- }
- static int loop_validate_file(struct file *file, struct block_device *bdev)
- {
- struct inode *inode = file->f_mapping->host;
- struct file *f = file;
- /* Avoid recursion */
- while (is_loop_device(f)) {
- struct loop_device *l;
- lockdep_assert_held(&loop_validate_mutex);
- if (f->f_mapping->host->i_rdev == bdev->bd_dev)
- return -EBADF;
- l = I_BDEV(f->f_mapping->host)->bd_disk->private_data;
- if (l->lo_state != Lo_bound)
- return -EINVAL;
- /* Order wrt setting lo->lo_backing_file in loop_configure(). */
- rmb();
- f = l->lo_backing_file;
- }
- if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
- return -EINVAL;
- return 0;
- }
- /*
- * loop_change_fd switched the backing store of a loopback device to
- * a new file. This is useful for operating system installers to free up
- * the original file and in High Availability environments to switch to
- * an alternative location for the content in case of server meltdown.
- * This can only work if the loop device is used read-only, and if the
- * new backing store is the same size and type as the old backing store.
- */
- static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
- unsigned int arg)
- {
- struct file *file = fget(arg);
- struct file *old_file;
- int error;
- bool partscan;
- bool is_loop;
- if (!file)
- return -EBADF;
- /* suppress uevents while reconfiguring the device */
- dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1);
- is_loop = is_loop_device(file);
- error = loop_global_lock_killable(lo, is_loop);
- if (error)
- goto out_putf;
- error = -ENXIO;
- if (lo->lo_state != Lo_bound)
- goto out_err;
- /* the loop device has to be read-only */
- error = -EINVAL;
- if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
- goto out_err;
- error = loop_validate_file(file, bdev);
- if (error)
- goto out_err;
- old_file = lo->lo_backing_file;
- error = -EINVAL;
- /* size of the new backing store needs to be the same */
- if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
- goto out_err;
- /* and ... switch */
- disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE);
- blk_mq_freeze_queue(lo->lo_queue);
- mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
- lo->lo_backing_file = file;
- lo->old_gfp_mask = mapping_gfp_mask(file->f_mapping);
- mapping_set_gfp_mask(file->f_mapping,
- lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
- loop_update_dio(lo);
- blk_mq_unfreeze_queue(lo->lo_queue);
- partscan = lo->lo_flags & LO_FLAGS_PARTSCAN;
- loop_global_unlock(lo, is_loop);
- /*
- * Flush loop_validate_file() before fput(), for l->lo_backing_file
- * might be pointing at old_file which might be the last reference.
- */
- if (!is_loop) {
- mutex_lock(&loop_validate_mutex);
- mutex_unlock(&loop_validate_mutex);
- }
- /*
- * We must drop file reference outside of lo_mutex as dropping
- * the file ref can take open_mutex which creates circular locking
- * dependency.
- */
- fput(old_file);
- if (partscan)
- loop_reread_partitions(lo);
- error = 0;
- done:
- /* enable and uncork uevent now that we are done */
- dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0);
- return error;
- out_err:
- loop_global_unlock(lo, is_loop);
- out_putf:
- fput(file);
- goto done;
- }
- /* loop sysfs attributes */
- static ssize_t loop_attr_show(struct device *dev, char *page,
- ssize_t (*callback)(struct loop_device *, char *))
- {
- struct gendisk *disk = dev_to_disk(dev);
- struct loop_device *lo = disk->private_data;
- return callback(lo, page);
- }
- #define LOOP_ATTR_RO(_name) \
- static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
- static ssize_t loop_attr_do_show_##_name(struct device *d, \
- struct device_attribute *attr, char *b) \
- { \
- return loop_attr_show(d, b, loop_attr_##_name##_show); \
- } \
- static struct device_attribute loop_attr_##_name = \
- __ATTR(_name, 0444, loop_attr_do_show_##_name, NULL);
- static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
- {
- ssize_t ret;
- char *p = NULL;
- spin_lock_irq(&lo->lo_lock);
- if (lo->lo_backing_file)
- p = file_path(lo->lo_backing_file, buf, PAGE_SIZE - 1);
- spin_unlock_irq(&lo->lo_lock);
- if (IS_ERR_OR_NULL(p))
- ret = PTR_ERR(p);
- else {
- ret = strlen(p);
- memmove(buf, p, ret);
- buf[ret++] = '\n';
- buf[ret] = 0;
- }
- return ret;
- }
- static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
- {
- return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_offset);
- }
- static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
- {
- return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
- }
- static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
- {
- int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
- return sysfs_emit(buf, "%s\n", autoclear ? "1" : "0");
- }
- static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
- {
- int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
- return sysfs_emit(buf, "%s\n", partscan ? "1" : "0");
- }
- static ssize_t loop_attr_dio_show(struct loop_device *lo, char *buf)
- {
- int dio = (lo->lo_flags & LO_FLAGS_DIRECT_IO);
- return sysfs_emit(buf, "%s\n", dio ? "1" : "0");
- }
- LOOP_ATTR_RO(backing_file);
- LOOP_ATTR_RO(offset);
- LOOP_ATTR_RO(sizelimit);
- LOOP_ATTR_RO(autoclear);
- LOOP_ATTR_RO(partscan);
- LOOP_ATTR_RO(dio);
- static struct attribute *loop_attrs[] = {
- &loop_attr_backing_file.attr,
- &loop_attr_offset.attr,
- &loop_attr_sizelimit.attr,
- &loop_attr_autoclear.attr,
- &loop_attr_partscan.attr,
- &loop_attr_dio.attr,
- NULL,
- };
- static struct attribute_group loop_attribute_group = {
- .name = "loop",
- .attrs= loop_attrs,
- };
- static void loop_sysfs_init(struct loop_device *lo)
- {
- lo->sysfs_inited = !sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
- &loop_attribute_group);
- }
- static void loop_sysfs_exit(struct loop_device *lo)
- {
- if (lo->sysfs_inited)
- sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
- &loop_attribute_group);
- }
- static void loop_config_discard(struct loop_device *lo)
- {
- struct file *file = lo->lo_backing_file;
- struct inode *inode = file->f_mapping->host;
- struct request_queue *q = lo->lo_queue;
- u32 granularity, max_discard_sectors;
- /*
- * If the backing device is a block device, mirror its zeroing
- * capability. Set the discard sectors to the block device's zeroing
- * capabilities because loop discards result in blkdev_issue_zeroout(),
- * not blkdev_issue_discard(). This maintains consistent behavior with
- * file-backed loop devices: discarded regions read back as zero.
- */
- if (S_ISBLK(inode->i_mode)) {
- struct request_queue *backingq = bdev_get_queue(I_BDEV(inode));
- max_discard_sectors = backingq->limits.max_write_zeroes_sectors;
- granularity = bdev_discard_granularity(I_BDEV(inode)) ?:
- queue_physical_block_size(backingq);
- /*
- * We use punch hole to reclaim the free space used by the
- * image a.k.a. discard.
- */
- } else if (!file->f_op->fallocate) {
- max_discard_sectors = 0;
- granularity = 0;
- } else {
- struct kstatfs sbuf;
- max_discard_sectors = UINT_MAX >> 9;
- if (!vfs_statfs(&file->f_path, &sbuf))
- granularity = sbuf.f_bsize;
- else
- max_discard_sectors = 0;
- }
- if (max_discard_sectors) {
- q->limits.discard_granularity = granularity;
- blk_queue_max_discard_sectors(q, max_discard_sectors);
- blk_queue_max_write_zeroes_sectors(q, max_discard_sectors);
- } else {
- q->limits.discard_granularity = 0;
- blk_queue_max_discard_sectors(q, 0);
- blk_queue_max_write_zeroes_sectors(q, 0);
- }
- }
- struct loop_worker {
- struct rb_node rb_node;
- struct work_struct work;
- struct list_head cmd_list;
- struct list_head idle_list;
- struct loop_device *lo;
- struct cgroup_subsys_state *blkcg_css;
- unsigned long last_ran_at;
- };
- static void loop_workfn(struct work_struct *work);
- #ifdef CONFIG_BLK_CGROUP
- static inline int queue_on_root_worker(struct cgroup_subsys_state *css)
- {
- return !css || css == blkcg_root_css;
- }
- #else
- static inline int queue_on_root_worker(struct cgroup_subsys_state *css)
- {
- return !css;
- }
- #endif
- static void loop_queue_work(struct loop_device *lo, struct loop_cmd *cmd)
- {
- struct rb_node **node, *parent = NULL;
- struct loop_worker *cur_worker, *worker = NULL;
- struct work_struct *work;
- struct list_head *cmd_list;
- spin_lock_irq(&lo->lo_work_lock);
- if (queue_on_root_worker(cmd->blkcg_css))
- goto queue_work;
- node = &lo->worker_tree.rb_node;
- while (*node) {
- parent = *node;
- cur_worker = container_of(*node, struct loop_worker, rb_node);
- if (cur_worker->blkcg_css == cmd->blkcg_css) {
- worker = cur_worker;
- break;
- } else if ((long)cur_worker->blkcg_css < (long)cmd->blkcg_css) {
- node = &(*node)->rb_left;
- } else {
- node = &(*node)->rb_right;
- }
- }
- if (worker)
- goto queue_work;
- worker = kzalloc(sizeof(struct loop_worker), GFP_NOWAIT | __GFP_NOWARN);
- /*
- * In the event we cannot allocate a worker, just queue on the
- * rootcg worker and issue the I/O as the rootcg
- */
- if (!worker) {
- cmd->blkcg_css = NULL;
- if (cmd->memcg_css)
- css_put(cmd->memcg_css);
- cmd->memcg_css = NULL;
- goto queue_work;
- }
- worker->blkcg_css = cmd->blkcg_css;
- css_get(worker->blkcg_css);
- INIT_WORK(&worker->work, loop_workfn);
- INIT_LIST_HEAD(&worker->cmd_list);
- INIT_LIST_HEAD(&worker->idle_list);
- worker->lo = lo;
- rb_link_node(&worker->rb_node, parent, node);
- rb_insert_color(&worker->rb_node, &lo->worker_tree);
- queue_work:
- if (worker) {
- /*
- * We need to remove from the idle list here while
- * holding the lock so that the idle timer doesn't
- * free the worker
- */
- if (!list_empty(&worker->idle_list))
- list_del_init(&worker->idle_list);
- work = &worker->work;
- cmd_list = &worker->cmd_list;
- } else {
- work = &lo->rootcg_work;
- cmd_list = &lo->rootcg_cmd_list;
- }
- list_add_tail(&cmd->list_entry, cmd_list);
- queue_work(lo->workqueue, work);
- spin_unlock_irq(&lo->lo_work_lock);
- }
- static void loop_set_timer(struct loop_device *lo)
- {
- timer_reduce(&lo->timer, jiffies + LOOP_IDLE_WORKER_TIMEOUT);
- }
- static void loop_free_idle_workers(struct loop_device *lo, bool delete_all)
- {
- struct loop_worker *pos, *worker;
- spin_lock_irq(&lo->lo_work_lock);
- list_for_each_entry_safe(worker, pos, &lo->idle_worker_list,
- idle_list) {
- if (!delete_all &&
- time_is_after_jiffies(worker->last_ran_at +
- LOOP_IDLE_WORKER_TIMEOUT))
- break;
- list_del(&worker->idle_list);
- rb_erase(&worker->rb_node, &lo->worker_tree);
- css_put(worker->blkcg_css);
- kfree(worker);
- }
- if (!list_empty(&lo->idle_worker_list))
- loop_set_timer(lo);
- spin_unlock_irq(&lo->lo_work_lock);
- }
- static void loop_free_idle_workers_timer(struct timer_list *timer)
- {
- struct loop_device *lo = container_of(timer, struct loop_device, timer);
- return loop_free_idle_workers(lo, false);
- }
- static void loop_update_rotational(struct loop_device *lo)
- {
- struct file *file = lo->lo_backing_file;
- struct inode *file_inode = file->f_mapping->host;
- struct block_device *file_bdev = file_inode->i_sb->s_bdev;
- struct request_queue *q = lo->lo_queue;
- bool nonrot = true;
- /* not all filesystems (e.g. tmpfs) have a sb->s_bdev */
- if (file_bdev)
- nonrot = bdev_nonrot(file_bdev);
- if (nonrot)
- blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
- else
- blk_queue_flag_clear(QUEUE_FLAG_NONROT, q);
- }
- /**
- * loop_set_status_from_info - configure device from loop_info
- * @lo: struct loop_device to configure
- * @info: struct loop_info64 to configure the device with
- *
- * Configures the loop device parameters according to the passed
- * in loop_info64 configuration.
- */
- static int
- loop_set_status_from_info(struct loop_device *lo,
- const struct loop_info64 *info)
- {
- if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
- return -EINVAL;
- switch (info->lo_encrypt_type) {
- case LO_CRYPT_NONE:
- break;
- case LO_CRYPT_XOR:
- pr_warn("support for the xor transformation has been removed.\n");
- return -EINVAL;
- case LO_CRYPT_CRYPTOAPI:
- pr_warn("support for cryptoloop has been removed. Use dm-crypt instead.\n");
- return -EINVAL;
- default:
- return -EINVAL;
- }
- /* Avoid assigning overflow values */
- if (info->lo_offset > LLONG_MAX || info->lo_sizelimit > LLONG_MAX)
- return -EOVERFLOW;
- lo->lo_offset = info->lo_offset;
- lo->lo_sizelimit = info->lo_sizelimit;
- memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
- lo->lo_file_name[LO_NAME_SIZE-1] = 0;
- lo->lo_flags = info->lo_flags;
- return 0;
- }
- static int loop_configure(struct loop_device *lo, fmode_t mode,
- struct block_device *bdev,
- const struct loop_config *config)
- {
- struct file *file = fget(config->fd);
- struct inode *inode;
- struct address_space *mapping;
- int error;
- loff_t size;
- bool partscan;
- unsigned short bsize;
- bool is_loop;
- if (!file)
- return -EBADF;
- is_loop = is_loop_device(file);
- /* This is safe, since we have a reference from open(). */
- __module_get(THIS_MODULE);
- /*
- * If we don't hold exclusive handle for the device, upgrade to it
- * here to avoid changing device under exclusive owner.
- */
- if (!(mode & FMODE_EXCL)) {
- error = bd_prepare_to_claim(bdev, loop_configure);
- if (error)
- goto out_putf;
- }
- error = loop_global_lock_killable(lo, is_loop);
- if (error)
- goto out_bdev;
- error = -EBUSY;
- if (lo->lo_state != Lo_unbound)
- goto out_unlock;
- error = loop_validate_file(file, bdev);
- if (error)
- goto out_unlock;
- mapping = file->f_mapping;
- inode = mapping->host;
- if ((config->info.lo_flags & ~LOOP_CONFIGURE_SETTABLE_FLAGS) != 0) {
- error = -EINVAL;
- goto out_unlock;
- }
- if (config->block_size) {
- error = blk_validate_block_size(config->block_size);
- if (error)
- goto out_unlock;
- }
- error = loop_set_status_from_info(lo, &config->info);
- if (error)
- goto out_unlock;
- if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
- !file->f_op->write_iter)
- lo->lo_flags |= LO_FLAGS_READ_ONLY;
- if (!lo->workqueue) {
- lo->workqueue = alloc_workqueue("loop%d",
- WQ_UNBOUND | WQ_FREEZABLE,
- 0, lo->lo_number);
- if (!lo->workqueue) {
- error = -ENOMEM;
- goto out_unlock;
- }
- }
- /* suppress uevents while reconfiguring the device */
- dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1);
- disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE);
- set_disk_ro(lo->lo_disk, (lo->lo_flags & LO_FLAGS_READ_ONLY) != 0);
- lo->use_dio = lo->lo_flags & LO_FLAGS_DIRECT_IO;
- lo->lo_device = bdev;
- lo->lo_backing_file = file;
- lo->old_gfp_mask = mapping_gfp_mask(mapping);
- mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
- if (!(lo->lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
- blk_queue_write_cache(lo->lo_queue, true, false);
- if (config->block_size)
- bsize = config->block_size;
- else if ((lo->lo_backing_file->f_flags & O_DIRECT) && inode->i_sb->s_bdev)
- /* In case of direct I/O, match underlying block size */
- bsize = bdev_logical_block_size(inode->i_sb->s_bdev);
- else
- bsize = 512;
- blk_queue_logical_block_size(lo->lo_queue, bsize);
- blk_queue_physical_block_size(lo->lo_queue, bsize);
- blk_queue_io_min(lo->lo_queue, bsize);
- loop_config_discard(lo);
- loop_update_rotational(lo);
- loop_update_dio(lo);
- loop_sysfs_init(lo);
- size = get_loop_size(lo, file);
- loop_set_size(lo, size);
- /* Order wrt reading lo_state in loop_validate_file(). */
- wmb();
- lo->lo_state = Lo_bound;
- if (part_shift)
- lo->lo_flags |= LO_FLAGS_PARTSCAN;
- partscan = lo->lo_flags & LO_FLAGS_PARTSCAN;
- if (partscan)
- clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
- /* enable and uncork uevent now that we are done */
- dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0);
- loop_global_unlock(lo, is_loop);
- if (partscan)
- loop_reread_partitions(lo);
- if (!(mode & FMODE_EXCL))
- bd_abort_claiming(bdev, loop_configure);
- return 0;
- out_unlock:
- loop_global_unlock(lo, is_loop);
- out_bdev:
- if (!(mode & FMODE_EXCL))
- bd_abort_claiming(bdev, loop_configure);
- out_putf:
- fput(file);
- /* This is safe: open() is still holding a reference. */
- module_put(THIS_MODULE);
- return error;
- }
- static void __loop_clr_fd(struct loop_device *lo, bool release)
- {
- struct file *filp;
- gfp_t gfp = lo->old_gfp_mask;
- if (test_bit(QUEUE_FLAG_WC, &lo->lo_queue->queue_flags))
- blk_queue_write_cache(lo->lo_queue, false, false);
- /*
- * Freeze the request queue when unbinding on a live file descriptor and
- * thus an open device. When called from ->release we are guaranteed
- * that there is no I/O in progress already.
- */
- if (!release)
- blk_mq_freeze_queue(lo->lo_queue);
- spin_lock_irq(&lo->lo_lock);
- filp = lo->lo_backing_file;
- lo->lo_backing_file = NULL;
- spin_unlock_irq(&lo->lo_lock);
- lo->lo_device = NULL;
- lo->lo_offset = 0;
- lo->lo_sizelimit = 0;
- memset(lo->lo_file_name, 0, LO_NAME_SIZE);
- blk_queue_logical_block_size(lo->lo_queue, 512);
- blk_queue_physical_block_size(lo->lo_queue, 512);
- blk_queue_io_min(lo->lo_queue, 512);
- invalidate_disk(lo->lo_disk);
- loop_sysfs_exit(lo);
- /* let user-space know about this change */
- kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE);
- mapping_set_gfp_mask(filp->f_mapping, gfp);
- /* This is safe: open() is still holding a reference. */
- module_put(THIS_MODULE);
- if (!release)
- blk_mq_unfreeze_queue(lo->lo_queue);
- disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE);
- if (lo->lo_flags & LO_FLAGS_PARTSCAN) {
- int err;
- /*
- * open_mutex has been held already in release path, so don't
- * acquire it if this function is called in such case.
- *
- * If the reread partition isn't from release path, lo_refcnt
- * must be at least one and it can only become zero when the
- * current holder is released.
- */
- if (!release)
- mutex_lock(&lo->lo_disk->open_mutex);
- err = bdev_disk_changed(lo->lo_disk, false);
- if (!release)
- mutex_unlock(&lo->lo_disk->open_mutex);
- if (err)
- pr_warn("%s: partition scan of loop%d failed (rc=%d)\n",
- __func__, lo->lo_number, err);
- /* Device is gone, no point in returning error */
- }
- /*
- * lo->lo_state is set to Lo_unbound here after above partscan has
- * finished. There cannot be anybody else entering __loop_clr_fd() as
- * Lo_rundown state protects us from all the other places trying to
- * change the 'lo' device.
- */
- lo->lo_flags = 0;
- if (!part_shift)
- set_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
- mutex_lock(&lo->lo_mutex);
- lo->lo_state = Lo_unbound;
- mutex_unlock(&lo->lo_mutex);
- /*
- * Need not hold lo_mutex to fput backing file. Calling fput holding
- * lo_mutex triggers a circular lock dependency possibility warning as
- * fput can take open_mutex which is usually taken before lo_mutex.
- */
- fput(filp);
- }
- static int loop_clr_fd(struct loop_device *lo)
- {
- int err;
- /*
- * Since lo_ioctl() is called without locks held, it is possible that
- * loop_configure()/loop_change_fd() and loop_clr_fd() run in parallel.
- *
- * Therefore, use global lock when setting Lo_rundown state in order to
- * make sure that loop_validate_file() will fail if the "struct file"
- * which loop_configure()/loop_change_fd() found via fget() was this
- * loop device.
- */
- err = loop_global_lock_killable(lo, true);
- if (err)
- return err;
- if (lo->lo_state != Lo_bound) {
- loop_global_unlock(lo, true);
- return -ENXIO;
- }
- /*
- * If we've explicitly asked to tear down the loop device,
- * and it has an elevated reference count, set it for auto-teardown when
- * the last reference goes away. This stops $!~#$@ udev from
- * preventing teardown because it decided that it needs to run blkid on
- * the loopback device whenever they appear. xfstests is notorious for
- * failing tests because blkid via udev races with a losetup
- * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d
- * command to fail with EBUSY.
- */
- if (disk_openers(lo->lo_disk) > 1) {
- lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
- loop_global_unlock(lo, true);
- return 0;
- }
- lo->lo_state = Lo_rundown;
- loop_global_unlock(lo, true);
- __loop_clr_fd(lo, false);
- return 0;
- }
- static int
- loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
- {
- int err;
- int prev_lo_flags;
- bool partscan = false;
- bool size_changed = false;
- err = mutex_lock_killable(&lo->lo_mutex);
- if (err)
- return err;
- if (lo->lo_state != Lo_bound) {
- err = -ENXIO;
- goto out_unlock;
- }
- if (lo->lo_offset != info->lo_offset ||
- lo->lo_sizelimit != info->lo_sizelimit) {
- size_changed = true;
- sync_blockdev(lo->lo_device);
- invalidate_bdev(lo->lo_device);
- }
- /* I/O need to be drained during transfer transition */
- blk_mq_freeze_queue(lo->lo_queue);
- prev_lo_flags = lo->lo_flags;
- err = loop_set_status_from_info(lo, info);
- if (err)
- goto out_unfreeze;
- /* Mask out flags that can't be set using LOOP_SET_STATUS. */
- lo->lo_flags &= LOOP_SET_STATUS_SETTABLE_FLAGS;
- /* For those flags, use the previous values instead */
- lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_SETTABLE_FLAGS;
- /* For flags that can't be cleared, use previous values too */
- lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_CLEARABLE_FLAGS;
- if (size_changed) {
- loff_t new_size = get_size(lo->lo_offset, lo->lo_sizelimit,
- lo->lo_backing_file);
- loop_set_size(lo, new_size);
- }
- loop_config_discard(lo);
- /* update dio if lo_offset or transfer is changed */
- __loop_update_dio(lo, lo->use_dio);
- out_unfreeze:
- blk_mq_unfreeze_queue(lo->lo_queue);
- if (!err && (lo->lo_flags & LO_FLAGS_PARTSCAN) &&
- !(prev_lo_flags & LO_FLAGS_PARTSCAN)) {
- clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
- partscan = true;
- }
- out_unlock:
- mutex_unlock(&lo->lo_mutex);
- if (partscan)
- loop_reread_partitions(lo);
- return err;
- }
- static int
- loop_get_status(struct loop_device *lo, struct loop_info64 *info)
- {
- struct path path;
- struct kstat stat;
- int ret;
- ret = mutex_lock_killable(&lo->lo_mutex);
- if (ret)
- return ret;
- if (lo->lo_state != Lo_bound) {
- mutex_unlock(&lo->lo_mutex);
- return -ENXIO;
- }
- memset(info, 0, sizeof(*info));
- info->lo_number = lo->lo_number;
- info->lo_offset = lo->lo_offset;
- info->lo_sizelimit = lo->lo_sizelimit;
- info->lo_flags = lo->lo_flags;
- memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
- /* Drop lo_mutex while we call into the filesystem. */
- path = lo->lo_backing_file->f_path;
- path_get(&path);
- mutex_unlock(&lo->lo_mutex);
- ret = vfs_getattr(&path, &stat, STATX_INO, AT_STATX_SYNC_AS_STAT);
- if (!ret) {
- info->lo_device = huge_encode_dev(stat.dev);
- info->lo_inode = stat.ino;
- info->lo_rdevice = huge_encode_dev(stat.rdev);
- }
- path_put(&path);
- return ret;
- }
- static void
- loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
- {
- memset(info64, 0, sizeof(*info64));
- info64->lo_number = info->lo_number;
- info64->lo_device = info->lo_device;
- info64->lo_inode = info->lo_inode;
- info64->lo_rdevice = info->lo_rdevice;
- info64->lo_offset = info->lo_offset;
- info64->lo_sizelimit = 0;
- info64->lo_flags = info->lo_flags;
- memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
- }
- static int
- loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
- {
- memset(info, 0, sizeof(*info));
- info->lo_number = info64->lo_number;
- info->lo_device = info64->lo_device;
- info->lo_inode = info64->lo_inode;
- info->lo_rdevice = info64->lo_rdevice;
- info->lo_offset = info64->lo_offset;
- info->lo_flags = info64->lo_flags;
- memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
- /* error in case values were truncated */
- if (info->lo_device != info64->lo_device ||
- info->lo_rdevice != info64->lo_rdevice ||
- info->lo_inode != info64->lo_inode ||
- info->lo_offset != info64->lo_offset)
- return -EOVERFLOW;
- return 0;
- }
- static int
- loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
- {
- struct loop_info info;
- struct loop_info64 info64;
- if (copy_from_user(&info, arg, sizeof (struct loop_info)))
- return -EFAULT;
- loop_info64_from_old(&info, &info64);
- return loop_set_status(lo, &info64);
- }
- static int
- loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
- {
- struct loop_info64 info64;
- if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
- return -EFAULT;
- return loop_set_status(lo, &info64);
- }
- static int
- loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
- struct loop_info info;
- struct loop_info64 info64;
- int err;
- if (!arg)
- return -EINVAL;
- err = loop_get_status(lo, &info64);
- if (!err)
- err = loop_info64_to_old(&info64, &info);
- if (!err && copy_to_user(arg, &info, sizeof(info)))
- err = -EFAULT;
- return err;
- }
- static int
- loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
- struct loop_info64 info64;
- int err;
- if (!arg)
- return -EINVAL;
- err = loop_get_status(lo, &info64);
- if (!err && copy_to_user(arg, &info64, sizeof(info64)))
- err = -EFAULT;
- return err;
- }
- static int loop_set_capacity(struct loop_device *lo)
- {
- loff_t size;
- if (unlikely(lo->lo_state != Lo_bound))
- return -ENXIO;
- size = get_loop_size(lo, lo->lo_backing_file);
- loop_set_size(lo, size);
- return 0;
- }
- static int loop_set_dio(struct loop_device *lo, unsigned long arg)
- {
- int error = -ENXIO;
- if (lo->lo_state != Lo_bound)
- goto out;
- __loop_update_dio(lo, !!arg);
- if (lo->use_dio == !!arg)
- return 0;
- error = -EINVAL;
- out:
- return error;
- }
- static int loop_set_block_size(struct loop_device *lo, unsigned long arg)
- {
- int err = 0;
- if (lo->lo_state != Lo_bound)
- return -ENXIO;
- err = blk_validate_block_size(arg);
- if (err)
- return err;
- if (lo->lo_queue->limits.logical_block_size == arg)
- return 0;
- sync_blockdev(lo->lo_device);
- invalidate_bdev(lo->lo_device);
- blk_mq_freeze_queue(lo->lo_queue);
- blk_queue_logical_block_size(lo->lo_queue, arg);
- blk_queue_physical_block_size(lo->lo_queue, arg);
- blk_queue_io_min(lo->lo_queue, arg);
- loop_update_dio(lo);
- blk_mq_unfreeze_queue(lo->lo_queue);
- return err;
- }
- static int lo_simple_ioctl(struct loop_device *lo, unsigned int cmd,
- unsigned long arg)
- {
- int err;
- err = mutex_lock_killable(&lo->lo_mutex);
- if (err)
- return err;
- switch (cmd) {
- case LOOP_SET_CAPACITY:
- err = loop_set_capacity(lo);
- break;
- case LOOP_SET_DIRECT_IO:
- err = loop_set_dio(lo, arg);
- break;
- case LOOP_SET_BLOCK_SIZE:
- err = loop_set_block_size(lo, arg);
- break;
- default:
- err = -EINVAL;
- }
- mutex_unlock(&lo->lo_mutex);
- return err;
- }
- static int lo_ioctl(struct block_device *bdev, fmode_t mode,
- unsigned int cmd, unsigned long arg)
- {
- struct loop_device *lo = bdev->bd_disk->private_data;
- void __user *argp = (void __user *) arg;
- int err;
- switch (cmd) {
- case LOOP_SET_FD: {
- /*
- * Legacy case - pass in a zeroed out struct loop_config with
- * only the file descriptor set , which corresponds with the
- * default parameters we'd have used otherwise.
- */
- struct loop_config config;
- memset(&config, 0, sizeof(config));
- config.fd = arg;
- return loop_configure(lo, mode, bdev, &config);
- }
- case LOOP_CONFIGURE: {
- struct loop_config config;
- if (copy_from_user(&config, argp, sizeof(config)))
- return -EFAULT;
- return loop_configure(lo, mode, bdev, &config);
- }
- case LOOP_CHANGE_FD:
- return loop_change_fd(lo, bdev, arg);
- case LOOP_CLR_FD:
- return loop_clr_fd(lo);
- case LOOP_SET_STATUS:
- err = -EPERM;
- if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) {
- err = loop_set_status_old(lo, argp);
- }
- break;
- case LOOP_GET_STATUS:
- return loop_get_status_old(lo, argp);
- case LOOP_SET_STATUS64:
- err = -EPERM;
- if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) {
- err = loop_set_status64(lo, argp);
- }
- break;
- case LOOP_GET_STATUS64:
- return loop_get_status64(lo, argp);
- case LOOP_SET_CAPACITY:
- case LOOP_SET_DIRECT_IO:
- case LOOP_SET_BLOCK_SIZE:
- if (!(mode & FMODE_WRITE) && !capable(CAP_SYS_ADMIN))
- return -EPERM;
- fallthrough;
- default:
- err = lo_simple_ioctl(lo, cmd, arg);
- break;
- }
- return err;
- }
- #ifdef CONFIG_COMPAT
- struct compat_loop_info {
- compat_int_t lo_number; /* ioctl r/o */
- compat_dev_t lo_device; /* ioctl r/o */
- compat_ulong_t lo_inode; /* ioctl r/o */
- compat_dev_t lo_rdevice; /* ioctl r/o */
- compat_int_t lo_offset;
- compat_int_t lo_encrypt_type; /* obsolete, ignored */
- compat_int_t lo_encrypt_key_size; /* ioctl w/o */
- compat_int_t lo_flags; /* ioctl r/o */
- char lo_name[LO_NAME_SIZE];
- unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
- compat_ulong_t lo_init[2];
- char reserved[4];
- };
- /*
- * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
- * - noinlined to reduce stack space usage in main part of driver
- */
- static noinline int
- loop_info64_from_compat(const struct compat_loop_info __user *arg,
- struct loop_info64 *info64)
- {
- struct compat_loop_info info;
- if (copy_from_user(&info, arg, sizeof(info)))
- return -EFAULT;
- memset(info64, 0, sizeof(*info64));
- info64->lo_number = info.lo_number;
- info64->lo_device = info.lo_device;
- info64->lo_inode = info.lo_inode;
- info64->lo_rdevice = info.lo_rdevice;
- info64->lo_offset = info.lo_offset;
- info64->lo_sizelimit = 0;
- info64->lo_flags = info.lo_flags;
- memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
- return 0;
- }
- /*
- * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
- * - noinlined to reduce stack space usage in main part of driver
- */
- static noinline int
- loop_info64_to_compat(const struct loop_info64 *info64,
- struct compat_loop_info __user *arg)
- {
- struct compat_loop_info info;
- memset(&info, 0, sizeof(info));
- info.lo_number = info64->lo_number;
- info.lo_device = info64->lo_device;
- info.lo_inode = info64->lo_inode;
- info.lo_rdevice = info64->lo_rdevice;
- info.lo_offset = info64->lo_offset;
- info.lo_flags = info64->lo_flags;
- memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
- /* error in case values were truncated */
- if (info.lo_device != info64->lo_device ||
- info.lo_rdevice != info64->lo_rdevice ||
- info.lo_inode != info64->lo_inode ||
- info.lo_offset != info64->lo_offset)
- return -EOVERFLOW;
- if (copy_to_user(arg, &info, sizeof(info)))
- return -EFAULT;
- return 0;
- }
- static int
- loop_set_status_compat(struct loop_device *lo,
- const struct compat_loop_info __user *arg)
- {
- struct loop_info64 info64;
- int ret;
- ret = loop_info64_from_compat(arg, &info64);
- if (ret < 0)
- return ret;
- return loop_set_status(lo, &info64);
- }
- static int
- loop_get_status_compat(struct loop_device *lo,
- struct compat_loop_info __user *arg)
- {
- struct loop_info64 info64;
- int err;
- if (!arg)
- return -EINVAL;
- err = loop_get_status(lo, &info64);
- if (!err)
- err = loop_info64_to_compat(&info64, arg);
- return err;
- }
- static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
- unsigned int cmd, unsigned long arg)
- {
- struct loop_device *lo = bdev->bd_disk->private_data;
- int err;
- switch(cmd) {
- case LOOP_SET_STATUS:
- err = loop_set_status_compat(lo,
- (const struct compat_loop_info __user *)arg);
- break;
- case LOOP_GET_STATUS:
- err = loop_get_status_compat(lo,
- (struct compat_loop_info __user *)arg);
- break;
- case LOOP_SET_CAPACITY:
- case LOOP_CLR_FD:
- case LOOP_GET_STATUS64:
- case LOOP_SET_STATUS64:
- case LOOP_CONFIGURE:
- arg = (unsigned long) compat_ptr(arg);
- fallthrough;
- case LOOP_SET_FD:
- case LOOP_CHANGE_FD:
- case LOOP_SET_BLOCK_SIZE:
- case LOOP_SET_DIRECT_IO:
- err = lo_ioctl(bdev, mode, cmd, arg);
- break;
- default:
- err = -ENOIOCTLCMD;
- break;
- }
- return err;
- }
- #endif
- static void lo_release(struct gendisk *disk, fmode_t mode)
- {
- struct loop_device *lo = disk->private_data;
- if (disk_openers(disk) > 0)
- return;
- mutex_lock(&lo->lo_mutex);
- if (lo->lo_state == Lo_bound && (lo->lo_flags & LO_FLAGS_AUTOCLEAR)) {
- lo->lo_state = Lo_rundown;
- mutex_unlock(&lo->lo_mutex);
- /*
- * In autoclear mode, stop the loop thread
- * and remove configuration after last close.
- */
- __loop_clr_fd(lo, true);
- return;
- }
- mutex_unlock(&lo->lo_mutex);
- }
- static void lo_free_disk(struct gendisk *disk)
- {
- struct loop_device *lo = disk->private_data;
- if (lo->workqueue)
- destroy_workqueue(lo->workqueue);
- loop_free_idle_workers(lo, true);
- del_timer_sync(&lo->timer);
- mutex_destroy(&lo->lo_mutex);
- kfree(lo);
- }
- static const struct block_device_operations lo_fops = {
- .owner = THIS_MODULE,
- .release = lo_release,
- .ioctl = lo_ioctl,
- #ifdef CONFIG_COMPAT
- .compat_ioctl = lo_compat_ioctl,
- #endif
- .free_disk = lo_free_disk,
- };
- /*
- * And now the modules code and kernel interface.
- */
- /*
- * If max_loop is specified, create that many devices upfront.
- * This also becomes a hard limit. If max_loop is not specified,
- * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
- * init time. Loop devices can be requested on-demand with the
- * /dev/loop-control interface, or be instantiated by accessing
- * a 'dead' device node.
- */
- static int max_loop = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
- module_param(max_loop, int, 0444);
- MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
- module_param(max_part, int, 0444);
- MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
- static int hw_queue_depth = LOOP_DEFAULT_HW_Q_DEPTH;
- static int loop_set_hw_queue_depth(const char *s, const struct kernel_param *p)
- {
- int ret = kstrtoint(s, 10, &hw_queue_depth);
- return (ret || (hw_queue_depth < 1)) ? -EINVAL : 0;
- }
- static const struct kernel_param_ops loop_hw_qdepth_param_ops = {
- .set = loop_set_hw_queue_depth,
- .get = param_get_int,
- };
- device_param_cb(hw_queue_depth, &loop_hw_qdepth_param_ops, &hw_queue_depth, 0444);
- MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: 128");
- MODULE_LICENSE("GPL");
- MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
- static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx,
- const struct blk_mq_queue_data *bd)
- {
- struct request *rq = bd->rq;
- struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
- struct loop_device *lo = rq->q->queuedata;
- blk_mq_start_request(rq);
- if (lo->lo_state != Lo_bound)
- return BLK_STS_IOERR;
- switch (req_op(rq)) {
- case REQ_OP_FLUSH:
- case REQ_OP_DISCARD:
- case REQ_OP_WRITE_ZEROES:
- cmd->use_aio = false;
- break;
- default:
- cmd->use_aio = lo->use_dio;
- break;
- }
- /* always use the first bio's css */
- cmd->blkcg_css = NULL;
- cmd->memcg_css = NULL;
- #ifdef CONFIG_BLK_CGROUP
- if (rq->bio) {
- cmd->blkcg_css = bio_blkcg_css(rq->bio);
- #ifdef CONFIG_MEMCG
- if (cmd->blkcg_css) {
- cmd->memcg_css =
- cgroup_get_e_css(cmd->blkcg_css->cgroup,
- &memory_cgrp_subsys);
- }
- #endif
- }
- #endif
- loop_queue_work(lo, cmd);
- return BLK_STS_OK;
- }
- static void loop_handle_cmd(struct loop_cmd *cmd)
- {
- struct cgroup_subsys_state *cmd_blkcg_css = cmd->blkcg_css;
- struct cgroup_subsys_state *cmd_memcg_css = cmd->memcg_css;
- struct request *rq = blk_mq_rq_from_pdu(cmd);
- const bool write = op_is_write(req_op(rq));
- struct loop_device *lo = rq->q->queuedata;
- int ret = 0;
- struct mem_cgroup *old_memcg = NULL;
- const bool use_aio = cmd->use_aio;
- if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) {
- ret = -EIO;
- goto failed;
- }
- if (cmd_blkcg_css)
- kthread_associate_blkcg(cmd_blkcg_css);
- if (cmd_memcg_css)
- old_memcg = set_active_memcg(
- mem_cgroup_from_css(cmd_memcg_css));
- /*
- * do_req_filebacked() may call blk_mq_complete_request() synchronously
- * or asynchronously if using aio. Hence, do not touch 'cmd' after
- * do_req_filebacked() has returned unless we are sure that 'cmd' has
- * not yet been completed.
- */
- ret = do_req_filebacked(lo, rq);
- if (cmd_blkcg_css)
- kthread_associate_blkcg(NULL);
- if (cmd_memcg_css) {
- set_active_memcg(old_memcg);
- css_put(cmd_memcg_css);
- }
- failed:
- /* complete non-aio request */
- if (!use_aio || ret) {
- if (ret == -EOPNOTSUPP)
- cmd->ret = ret;
- else
- cmd->ret = ret ? -EIO : 0;
- if (likely(!blk_should_fake_timeout(rq->q)))
- blk_mq_complete_request(rq);
- }
- }
- static void loop_process_work(struct loop_worker *worker,
- struct list_head *cmd_list, struct loop_device *lo)
- {
- int orig_flags = current->flags;
- struct loop_cmd *cmd;
- current->flags |= PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO;
- spin_lock_irq(&lo->lo_work_lock);
- while (!list_empty(cmd_list)) {
- cmd = container_of(
- cmd_list->next, struct loop_cmd, list_entry);
- list_del(cmd_list->next);
- spin_unlock_irq(&lo->lo_work_lock);
- loop_handle_cmd(cmd);
- cond_resched();
- spin_lock_irq(&lo->lo_work_lock);
- }
- /*
- * We only add to the idle list if there are no pending cmds
- * *and* the worker will not run again which ensures that it
- * is safe to free any worker on the idle list
- */
- if (worker && !work_pending(&worker->work)) {
- worker->last_ran_at = jiffies;
- list_add_tail(&worker->idle_list, &lo->idle_worker_list);
- loop_set_timer(lo);
- }
- spin_unlock_irq(&lo->lo_work_lock);
- current->flags = orig_flags;
- }
- static void loop_workfn(struct work_struct *work)
- {
- struct loop_worker *worker =
- container_of(work, struct loop_worker, work);
- loop_process_work(worker, &worker->cmd_list, worker->lo);
- }
- static void loop_rootcg_workfn(struct work_struct *work)
- {
- struct loop_device *lo =
- container_of(work, struct loop_device, rootcg_work);
- loop_process_work(NULL, &lo->rootcg_cmd_list, lo);
- }
- static const struct blk_mq_ops loop_mq_ops = {
- .queue_rq = loop_queue_rq,
- .complete = lo_complete_rq,
- };
- static int loop_add(int i)
- {
- struct loop_device *lo;
- struct gendisk *disk;
- int err;
- err = -ENOMEM;
- lo = kzalloc(sizeof(*lo), GFP_KERNEL);
- if (!lo)
- goto out;
- lo->worker_tree = RB_ROOT;
- INIT_LIST_HEAD(&lo->idle_worker_list);
- timer_setup(&lo->timer, loop_free_idle_workers_timer, TIMER_DEFERRABLE);
- lo->lo_state = Lo_unbound;
- err = mutex_lock_killable(&loop_ctl_mutex);
- if (err)
- goto out_free_dev;
- /* allocate id, if @id >= 0, we're requesting that specific id */
- if (i >= 0) {
- err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL);
- if (err == -ENOSPC)
- err = -EEXIST;
- } else {
- err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL);
- }
- mutex_unlock(&loop_ctl_mutex);
- if (err < 0)
- goto out_free_dev;
- i = err;
- lo->tag_set.ops = &loop_mq_ops;
- lo->tag_set.nr_hw_queues = 1;
- lo->tag_set.queue_depth = hw_queue_depth;
- lo->tag_set.numa_node = NUMA_NO_NODE;
- lo->tag_set.cmd_size = sizeof(struct loop_cmd);
- lo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING |
- BLK_MQ_F_NO_SCHED_BY_DEFAULT;
- lo->tag_set.driver_data = lo;
- err = blk_mq_alloc_tag_set(&lo->tag_set);
- if (err)
- goto out_free_idr;
- disk = lo->lo_disk = blk_mq_alloc_disk(&lo->tag_set, lo);
- if (IS_ERR(disk)) {
- err = PTR_ERR(disk);
- goto out_cleanup_tags;
- }
- lo->lo_queue = lo->lo_disk->queue;
- blk_queue_max_hw_sectors(lo->lo_queue, BLK_DEF_MAX_SECTORS);
- /*
- * By default, we do buffer IO, so it doesn't make sense to enable
- * merge because the I/O submitted to backing file is handled page by
- * page. For directio mode, merge does help to dispatch bigger request
- * to underlayer disk. We will enable merge once directio is enabled.
- */
- blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue);
- /*
- * Disable partition scanning by default. The in-kernel partition
- * scanning can be requested individually per-device during its
- * setup. Userspace can always add and remove partitions from all
- * devices. The needed partition minors are allocated from the
- * extended minor space, the main loop device numbers will continue
- * to match the loop minors, regardless of the number of partitions
- * used.
- *
- * If max_part is given, partition scanning is globally enabled for
- * all loop devices. The minors for the main loop devices will be
- * multiples of max_part.
- *
- * Note: Global-for-all-devices, set-only-at-init, read-only module
- * parameteters like 'max_loop' and 'max_part' make things needlessly
- * complicated, are too static, inflexible and may surprise
- * userspace tools. Parameters like this in general should be avoided.
- */
- if (!part_shift)
- set_bit(GD_SUPPRESS_PART_SCAN, &disk->state);
- mutex_init(&lo->lo_mutex);
- lo->lo_number = i;
- spin_lock_init(&lo->lo_lock);
- spin_lock_init(&lo->lo_work_lock);
- INIT_WORK(&lo->rootcg_work, loop_rootcg_workfn);
- INIT_LIST_HEAD(&lo->rootcg_cmd_list);
- disk->major = LOOP_MAJOR;
- disk->first_minor = i << part_shift;
- disk->minors = 1 << part_shift;
- disk->fops = &lo_fops;
- disk->private_data = lo;
- disk->queue = lo->lo_queue;
- disk->events = DISK_EVENT_MEDIA_CHANGE;
- disk->event_flags = DISK_EVENT_FLAG_UEVENT;
- sprintf(disk->disk_name, "loop%d", i);
- /* Make this loop device reachable from pathname. */
- err = add_disk(disk);
- if (err)
- goto out_cleanup_disk;
- /* Show this loop device. */
- mutex_lock(&loop_ctl_mutex);
- lo->idr_visible = true;
- mutex_unlock(&loop_ctl_mutex);
- return i;
- out_cleanup_disk:
- put_disk(disk);
- out_cleanup_tags:
- blk_mq_free_tag_set(&lo->tag_set);
- out_free_idr:
- mutex_lock(&loop_ctl_mutex);
- idr_remove(&loop_index_idr, i);
- mutex_unlock(&loop_ctl_mutex);
- out_free_dev:
- kfree(lo);
- out:
- return err;
- }
- static void loop_remove(struct loop_device *lo)
- {
- /* Make this loop device unreachable from pathname. */
- del_gendisk(lo->lo_disk);
- blk_mq_free_tag_set(&lo->tag_set);
- mutex_lock(&loop_ctl_mutex);
- idr_remove(&loop_index_idr, lo->lo_number);
- mutex_unlock(&loop_ctl_mutex);
- put_disk(lo->lo_disk);
- }
- static void loop_probe(dev_t dev)
- {
- int idx = MINOR(dev) >> part_shift;
- if (max_loop && idx >= max_loop)
- return;
- loop_add(idx);
- }
- static int loop_control_remove(int idx)
- {
- struct loop_device *lo;
- int ret;
- if (idx < 0) {
- pr_warn_once("deleting an unspecified loop device is not supported.\n");
- return -EINVAL;
- }
-
- /* Hide this loop device for serialization. */
- ret = mutex_lock_killable(&loop_ctl_mutex);
- if (ret)
- return ret;
- lo = idr_find(&loop_index_idr, idx);
- if (!lo || !lo->idr_visible)
- ret = -ENODEV;
- else
- lo->idr_visible = false;
- mutex_unlock(&loop_ctl_mutex);
- if (ret)
- return ret;
- /* Check whether this loop device can be removed. */
- ret = mutex_lock_killable(&lo->lo_mutex);
- if (ret)
- goto mark_visible;
- if (lo->lo_state != Lo_unbound || disk_openers(lo->lo_disk) > 0) {
- mutex_unlock(&lo->lo_mutex);
- ret = -EBUSY;
- goto mark_visible;
- }
- /* Mark this loop device as no more bound, but not quite unbound yet */
- lo->lo_state = Lo_deleting;
- mutex_unlock(&lo->lo_mutex);
- loop_remove(lo);
- return 0;
- mark_visible:
- /* Show this loop device again. */
- mutex_lock(&loop_ctl_mutex);
- lo->idr_visible = true;
- mutex_unlock(&loop_ctl_mutex);
- return ret;
- }
- static int loop_control_get_free(int idx)
- {
- struct loop_device *lo;
- int id, ret;
- ret = mutex_lock_killable(&loop_ctl_mutex);
- if (ret)
- return ret;
- idr_for_each_entry(&loop_index_idr, lo, id) {
- /* Hitting a race results in creating a new loop device which is harmless. */
- if (lo->idr_visible && data_race(lo->lo_state) == Lo_unbound)
- goto found;
- }
- mutex_unlock(&loop_ctl_mutex);
- return loop_add(-1);
- found:
- mutex_unlock(&loop_ctl_mutex);
- return id;
- }
- static long loop_control_ioctl(struct file *file, unsigned int cmd,
- unsigned long parm)
- {
- switch (cmd) {
- case LOOP_CTL_ADD:
- return loop_add(parm);
- case LOOP_CTL_REMOVE:
- return loop_control_remove(parm);
- case LOOP_CTL_GET_FREE:
- return loop_control_get_free(parm);
- default:
- return -ENOSYS;
- }
- }
- static const struct file_operations loop_ctl_fops = {
- .open = nonseekable_open,
- .unlocked_ioctl = loop_control_ioctl,
- .compat_ioctl = loop_control_ioctl,
- .owner = THIS_MODULE,
- .llseek = noop_llseek,
- };
- static struct miscdevice loop_misc = {
- .minor = LOOP_CTRL_MINOR,
- .name = "loop-control",
- .fops = &loop_ctl_fops,
- };
- MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
- MODULE_ALIAS("devname:loop-control");
- static int __init loop_init(void)
- {
- int i;
- int err;
- part_shift = 0;
- if (max_part > 0) {
- part_shift = fls(max_part);
- /*
- * Adjust max_part according to part_shift as it is exported
- * to user space so that user can decide correct minor number
- * if [s]he want to create more devices.
- *
- * Note that -1 is required because partition 0 is reserved
- * for the whole disk.
- */
- max_part = (1UL << part_shift) - 1;
- }
- if ((1UL << part_shift) > DISK_MAX_PARTS) {
- err = -EINVAL;
- goto err_out;
- }
- if (max_loop > 1UL << (MINORBITS - part_shift)) {
- err = -EINVAL;
- goto err_out;
- }
- err = misc_register(&loop_misc);
- if (err < 0)
- goto err_out;
- if (__register_blkdev(LOOP_MAJOR, "loop", loop_probe)) {
- err = -EIO;
- goto misc_out;
- }
- /* pre-create number of devices given by config or max_loop */
- for (i = 0; i < max_loop; i++)
- loop_add(i);
- printk(KERN_INFO "loop: module loaded\n");
- return 0;
- misc_out:
- misc_deregister(&loop_misc);
- err_out:
- return err;
- }
- static void __exit loop_exit(void)
- {
- struct loop_device *lo;
- int id;
- unregister_blkdev(LOOP_MAJOR, "loop");
- misc_deregister(&loop_misc);
- /*
- * There is no need to use loop_ctl_mutex here, for nobody else can
- * access loop_index_idr when this module is unloading (unless forced
- * module unloading is requested). If this is not a clean unloading,
- * we have no means to avoid kernel crash.
- */
- idr_for_each_entry(&loop_index_idr, lo, id)
- loop_remove(lo);
- idr_destroy(&loop_index_idr);
- }
- module_init(loop_init);
- module_exit(loop_exit);
- #ifndef MODULE
- static int __init max_loop_setup(char *str)
- {
- max_loop = simple_strtol(str, NULL, 0);
- return 1;
- }
- __setup("max_loop=", max_loop_setup);
- #endif
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