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-rw-r--r--drivers/block/loop.c2318
1 files changed, 2318 insertions, 0 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
new file mode 100644
index 000000000..12ff6f58b
--- /dev/null
+++ b/drivers/block/loop.c
@@ -0,0 +1,2318 @@
+// 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);
+}
+
+/*
+ * 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 that of
+ * the backing device.
+ */
+static bool lo_bdev_can_use_dio(struct loop_device *lo,
+ struct block_device *backing_bdev)
+{
+ unsigned short sb_bsize = bdev_logical_block_size(backing_bdev);
+
+ if (queue_logical_block_size(lo->lo_queue) < sb_bsize)
+ return false;
+ if (lo->lo_offset & (sb_bsize - 1))
+ return false;
+ return true;
+}
+
+static void __loop_update_dio(struct loop_device *lo, bool dio)
+{
+ struct file *file = lo->lo_backing_file;
+ struct inode *inode = file->f_mapping->host;
+ struct block_device *backing_bdev = NULL;
+ bool use_dio;
+
+ if (S_ISBLK(inode->i_mode))
+ backing_bdev = I_BDEV(inode);
+ else if (inode->i_sb->s_bdev)
+ backing_bdev = inode->i_sb->s_bdev;
+
+ use_dio = dio && (file->f_mode & FMODE_CAN_ODIRECT) &&
+ (!backing_bdev || lo_bdev_can_use_dio(lo, backing_bdev));
+
+ 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,
+ * the default isn't a hard limit (as before commit 85c50197716c
+ * changed the default value from 0 for max_loop=0 reasons), just
+ * 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;
+
+#ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD
+static bool max_loop_specified;
+
+static int max_loop_param_set_int(const char *val,
+ const struct kernel_param *kp)
+{
+ int ret;
+
+ ret = param_set_int(val, kp);
+ if (ret < 0)
+ return ret;
+
+ max_loop_specified = true;
+ return 0;
+}
+
+static const struct kernel_param_ops max_loop_param_ops = {
+ .set = max_loop_param_set_int,
+ .get = param_get_int,
+};
+
+module_param_cb(max_loop, &max_loop_param_ops, &max_loop, 0444);
+MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
+#else
+module_param(max_loop, int, 0444);
+MODULE_PARM_DESC(max_loop, "Initial number of loop devices");
+#endif
+
+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);
+}
+
+#ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD
+static void loop_probe(dev_t dev)
+{
+ int idx = MINOR(dev) >> part_shift;
+
+ if (max_loop_specified && max_loop && idx >= max_loop)
+ return;
+ loop_add(idx);
+}
+#else
+#define loop_probe NULL
+#endif /* !CONFIG_BLOCK_LEGACY_AUTOLOAD */
+
+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);
+#ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD
+ max_loop_specified = true;
+#endif
+ return 1;
+}
+
+__setup("max_loop=", max_loop_setup);
+#endif