--- /dev/null
+/*
+ * linux/drivers/block/loop.c
+ *
+ * Written by Theodore Ts'o, 3/29/93
+ *
+ * Copyright 1993 by Theodore Ts'o. Redistribution of this file is
+ * permitted under the GNU General Public License.
+ *
+ * DES encryption plus some minor changes by Werner Almesberger, 30-MAY-1993
+ * more DES encryption plus IDEA encryption by Nicholas J. Leon, June 20, 1996
+ *
+ * Modularized and updated for 1.1.16 kernel - Mitch Dsouza 28th May 1994
+ * Adapted for 1.3.59 kernel - Andries Brouwer, 1 Feb 1996
+ *
+ * Fixed do_loop_request() re-entrancy - Vincent.Renardias@waw.com Mar 20, 1997
+ *
+ * Added devfs support - Richard Gooch <rgooch@atnf.csiro.au> 16-Jan-1998
+ *
+ * Handle sparse backing files correctly - Kenn Humborg, Jun 28, 1998
+ *
+ * Loadable modules and other fixes by AK, 1998
+ *
+ * Make real block number available to downstream transfer functions, enables
+ * CBC (and relatives) mode encryption requiring unique IVs per data block.
+ * Reed H. Petty, rhp@draper.net
+ *
+ * Maximum number of loop devices now dynamic via max_loop module parameter.
+ * Russell Kroll <rkroll@exploits.org> 19990701
+ *
+ * Maximum number of loop devices when compiled-in now selectable by passing
+ * max_loop=<1-255> to the kernel on boot.
+ * Erik I. Bolsø, <eriki@himolde.no>, Oct 31, 1999
+ *
+ * Completely rewrite request handling to be make_request_fn style and
+ * non blocking, pushing work to a helper thread. Lots of fixes from
+ * Al Viro too.
+ * Jens Axboe <axboe@suse.de>, Nov 2000
+ *
+ * Support up to 256 loop devices
+ * Heinz Mauelshagen <mge@sistina.com>, Feb 2002
+ *
+ * Support for falling back on the write file operation when the address space
+ * operations write_begin is not available on the backing filesystem.
+ * Anton Altaparmakov, 16 Feb 2005
+ *
+ * Still To Fix:
+ * - Advisory locking is ignored here.
+ * - Should use an own CAP_* category instead of CAP_SYS_ADMIN
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/stat.h>
+#include <linux/errno.h>
+#include <linux/major.h>
+#include <linux/wait.h>
+#include <linux/blkdev.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/kthread.h>
+#include <linux/splice.h>
+#include <linux/sysfs.h>
+#include <linux/miscdevice.h>
+#include <linux/falloc.h>
+#include <linux/uio.h>
+#include "loop.h"
+
+#include <asm/uaccess.h>
+
+static DEFINE_IDR(loop_index_idr);
+static DEFINE_MUTEX(loop_index_mutex);
+
+static int max_part;
+static int part_shift;
+
+static struct workqueue_struct *loop_wq;
+
+static int transfer_xor(struct loop_device *lo, int cmd,
+ struct page *raw_page, unsigned raw_off,
+ struct page *loop_page, unsigned loop_off,
+ int size, sector_t real_block)
+{
+ char *raw_buf = kmap_atomic(raw_page) + raw_off;
+ char *loop_buf = kmap_atomic(loop_page) + loop_off;
+ char *in, *out, *key;
+ int i, keysize;
+
+ if (cmd == READ) {
+ in = raw_buf;
+ out = loop_buf;
+ } else {
+ in = loop_buf;
+ out = raw_buf;
+ }
+
+ key = lo->lo_encrypt_key;
+ keysize = lo->lo_encrypt_key_size;
+ for (i = 0; i < size; i++)
+ *out++ = *in++ ^ key[(i & 511) % keysize];
+
+ kunmap_atomic(loop_buf);
+ kunmap_atomic(raw_buf);
+ cond_resched();
+ return 0;
+}
+
+static int xor_init(struct loop_device *lo, const struct loop_info64 *info)
+{
+ if (unlikely(info->lo_encrypt_key_size <= 0))
+ return -EINVAL;
+ return 0;
+}
+
+static struct loop_func_table none_funcs = {
+ .number = LO_CRYPT_NONE,
+};
+
+static struct loop_func_table xor_funcs = {
+ .number = LO_CRYPT_XOR,
+ .transfer = transfer_xor,
+ .init = xor_init
+};
+
+/* xfer_funcs[0] is special - its release function is never called */
+static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = {
+ &none_funcs,
+ &xor_funcs
+};
+
+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 int
+figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
+{
+ loff_t size = get_size(offset, sizelimit, lo->lo_backing_file);
+ sector_t x = (sector_t)size;
+ struct block_device *bdev = lo->lo_device;
+
+ if (unlikely((loff_t)x != size))
+ return -EFBIG;
+ if (lo->lo_offset != offset)
+ lo->lo_offset = offset;
+ if (lo->lo_sizelimit != sizelimit)
+ lo->lo_sizelimit = sizelimit;
+ set_capacity(lo->lo_disk, x);
+ bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9);
+ /* let user-space know about the new size */
+ kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
+ return 0;
+}
+
+static inline int
+lo_do_transfer(struct loop_device *lo, int cmd,
+ struct page *rpage, unsigned roffs,
+ struct page *lpage, unsigned loffs,
+ int size, sector_t rblock)
+{
+ int ret;
+
+ ret = lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
+ if (likely(!ret))
+ return 0;
+
+ printk_ratelimited(KERN_ERR
+ "loop: Transfer error at byte offset %llu, length %i.\n",
+ (unsigned long long)rblock << 9, size);
+ return ret;
+}
+
+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_BVEC, bvec, 1, bvec->bv_len);
+
+ file_start_write(file);
+ bw = vfs_iter_write(file, &i, ppos);
+ 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;
+}
+
+/*
+ * This is the slow, transforming version that needs to double buffer the
+ * data as it cannot do the transformations in place without having direct
+ * access to the destination pages of the backing file.
+ */
+static int lo_write_transfer(struct loop_device *lo, struct request *rq,
+ loff_t pos)
+{
+ struct bio_vec bvec, b;
+ struct req_iterator iter;
+ struct page *page;
+ int ret = 0;
+
+ page = alloc_page(GFP_NOIO);
+ if (unlikely(!page))
+ return -ENOMEM;
+
+ rq_for_each_segment(bvec, rq, iter) {
+ ret = lo_do_transfer(lo, WRITE, page, 0, bvec.bv_page,
+ bvec.bv_offset, bvec.bv_len, pos >> 9);
+ if (unlikely(ret))
+ break;
+
+ b.bv_page = page;
+ b.bv_offset = 0;
+ b.bv_len = bvec.bv_len;
+ ret = lo_write_bvec(lo->lo_backing_file, &b, &pos);
+ if (ret < 0)
+ break;
+ }
+
+ __free_page(page);
+ 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_BVEC, &bvec, 1, bvec.bv_len);
+ len = vfs_iter_read(lo->lo_backing_file, &i, &pos);
+ 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_read_transfer(struct loop_device *lo, struct request *rq,
+ loff_t pos)
+{
+ struct bio_vec bvec, b;
+ struct req_iterator iter;
+ struct iov_iter i;
+ struct page *page;
+ ssize_t len;
+ int ret = 0;
+
+ page = alloc_page(GFP_NOIO);
+ if (unlikely(!page))
+ return -ENOMEM;
+
+ rq_for_each_segment(bvec, rq, iter) {
+ loff_t offset = pos;
+
+ b.bv_page = page;
+ b.bv_offset = 0;
+ b.bv_len = bvec.bv_len;
+
+ iov_iter_bvec(&i, ITER_BVEC, &b, 1, b.bv_len);
+ len = vfs_iter_read(lo->lo_backing_file, &i, &pos);
+ if (len < 0) {
+ ret = len;
+ goto out_free_page;
+ }
+
+ ret = lo_do_transfer(lo, READ, page, 0, bvec.bv_page,
+ bvec.bv_offset, len, offset >> 9);
+ if (ret)
+ goto out_free_page;
+
+ 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;
+ }
+ }
+
+ ret = 0;
+out_free_page:
+ __free_page(page);
+ return ret;
+}
+
+static int lo_discard(struct loop_device *lo, struct request *rq, loff_t pos)
+{
+ /*
+ * We use punch hole to reclaim the free space used by the
+ * image a.k.a. discard. However we do not support discard if
+ * encryption is enabled, because it may give an attacker
+ * useful information.
+ */
+ struct file *file = lo->lo_backing_file;
+ int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
+ int ret;
+
+ if ((!file->f_op->fallocate) || lo->lo_encrypt_key_size) {
+ ret = -EOPNOTSUPP;
+ goto out;
+ }
+
+ ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq));
+ if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP))
+ ret = -EIO;
+ out:
+ return ret;
+}
+
+static int lo_req_flush(struct loop_device *lo, struct request *rq)
+{
+ struct file *file = lo->lo_backing_file;
+ int ret = vfs_fsync(file, 0);
+ if (unlikely(ret && ret != -EINVAL))
+ ret = -EIO;
+
+ return ret;
+}
+
+static int do_req_filebacked(struct loop_device *lo, struct request *rq)
+{
+ loff_t pos;
+ int ret;
+
+ pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;
+
+ if (rq->cmd_flags & REQ_WRITE) {
+ if (rq->cmd_flags & REQ_FLUSH)
+ ret = lo_req_flush(lo, rq);
+ else if (rq->cmd_flags & REQ_DISCARD)
+ ret = lo_discard(lo, rq, pos);
+ else if (lo->transfer)
+ ret = lo_write_transfer(lo, rq, pos);
+ else
+ ret = lo_write_simple(lo, rq, pos);
+
+ } else {
+ if (lo->transfer)
+ ret = lo_read_transfer(lo, rq, pos);
+ else
+ ret = lo_read_simple(lo, rq, pos);
+ }
+
+ return ret;
+}
+
+struct switch_request {
+ struct file *file;
+ struct completion wait;
+};
+
+/*
+ * Do the actual switch; called from the BIO completion routine
+ */
+static void do_loop_switch(struct loop_device *lo, struct switch_request *p)
+{
+ struct file *file = p->file;
+ struct file *old_file = lo->lo_backing_file;
+ struct address_space *mapping;
+
+ /* if no new file, only flush of queued bios requested */
+ if (!file)
+ return;
+
+ mapping = file->f_mapping;
+ mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
+ lo->lo_backing_file = file;
+ lo->lo_blocksize = S_ISBLK(mapping->host->i_mode) ?
+ mapping->host->i_bdev->bd_block_size : PAGE_SIZE;
+ lo->old_gfp_mask = mapping_gfp_mask(mapping);
+ mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
+}
+
+/*
+ * loop_switch performs the hard work of switching a backing store.
+ * First it needs to flush existing IO, it does this by sending a magic
+ * BIO down the pipe. The completion of this BIO does the actual switch.
+ */
+static int loop_switch(struct loop_device *lo, struct file *file)
+{
+ struct switch_request w;
+
+ w.file = file;
+
+ /* freeze queue and wait for completion of scheduled requests */
+ blk_mq_freeze_queue(lo->lo_queue);
+
+ /* do the switch action */
+ do_loop_switch(lo, &w);
+
+ /* unfreeze */
+ blk_mq_unfreeze_queue(lo->lo_queue);
+
+ return 0;
+}
+
+/*
+ * Helper to flush the IOs in loop, but keeping loop thread running
+ */
+static int loop_flush(struct loop_device *lo)
+{
+ return loop_switch(lo, NULL);
+}
+
+/*
+ * 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, *old_file;
+ struct inode *inode;
+ int error;
+
+ error = -ENXIO;
+ if (lo->lo_state != Lo_bound)
+ goto out;
+
+ /* the loop device has to be read-only */
+ error = -EINVAL;
+ if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
+ goto out;
+
+ error = -EBADF;
+ file = fget(arg);
+ if (!file)
+ goto out;
+
+ inode = file->f_mapping->host;
+ old_file = lo->lo_backing_file;
+
+ error = -EINVAL;
+
+ if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
+ goto out_putf;
+
+ /* 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_putf;
+
+ /* and ... switch */
+ error = loop_switch(lo, file);
+ if (error)
+ goto out_putf;
+
+ fput(old_file);
+ if (lo->lo_flags & LO_FLAGS_PARTSCAN)
+ ioctl_by_bdev(bdev, BLKRRPART, 0);
+ return 0;
+
+ out_putf:
+ fput(file);
+ out:
+ return error;
+}
+
+static inline int is_loop_device(struct file *file)
+{
+ struct inode *i = file->f_mapping->host;
+
+ return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR;
+}
+
+/* loop sysfs attributes */
+
+static ssize_t loop_attr_show(struct device *dev, char *page,
+ ssize_t (*callback)(struct loop_device *, char *))
+{
+ struct 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, S_IRUGO, loop_attr_do_show_##_name, NULL);
+
+static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
+{
+ ssize_t ret;
+ char *p = NULL;
+
+ spin_lock_irq(&lo->lo_lock);
+ if (lo->lo_backing_file)
+ p = d_path(&lo->lo_backing_file->f_path, 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 sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset);
+}
+
+static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
+{
+ return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
+}
+
+static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
+{
+ int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
+
+ return sprintf(buf, "%s\n", autoclear ? "1" : "0");
+}
+
+static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
+{
+ int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
+
+ return sprintf(buf, "%s\n", partscan ? "1" : "0");
+}
+
+LOOP_ATTR_RO(backing_file);
+LOOP_ATTR_RO(offset);
+LOOP_ATTR_RO(sizelimit);
+LOOP_ATTR_RO(autoclear);
+LOOP_ATTR_RO(partscan);
+
+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,
+ NULL,
+};
+
+static struct attribute_group loop_attribute_group = {
+ .name = "loop",
+ .attrs= loop_attrs,
+};
+
+static int loop_sysfs_init(struct loop_device *lo)
+{
+ return sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
+ &loop_attribute_group);
+}
+
+static void loop_sysfs_exit(struct loop_device *lo)
+{
+ sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
+ &loop_attribute_group);
+}
+
+static 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;
+
+ /*
+ * We use punch hole to reclaim the free space used by the
+ * image a.k.a. discard. However we do not support discard if
+ * encryption is enabled, because it may give an attacker
+ * useful information.
+ */
+ if ((!file->f_op->fallocate) ||
+ lo->lo_encrypt_key_size) {
+ q->limits.discard_granularity = 0;
+ q->limits.discard_alignment = 0;
+ q->limits.max_discard_sectors = 0;
+ q->limits.discard_zeroes_data = 0;
+ queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
+ return;
+ }
+
+ q->limits.discard_granularity = inode->i_sb->s_blocksize;
+ q->limits.discard_alignment = 0;
+ q->limits.max_discard_sectors = UINT_MAX >> 9;
+ q->limits.discard_zeroes_data = 1;
+ queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
+}
+
+static int loop_set_fd(struct loop_device *lo, fmode_t mode,
+ struct block_device *bdev, unsigned int arg)
+{
+ struct file *file, *f;
+ struct inode *inode;
+ struct address_space *mapping;
+ unsigned lo_blocksize;
+ int lo_flags = 0;
+ int error;
+ loff_t size;
+
+ /* This is safe, since we have a reference from open(). */
+ __module_get(THIS_MODULE);
+
+ error = -EBADF;
+ file = fget(arg);
+ if (!file)
+ goto out;
+
+ error = -EBUSY;
+ if (lo->lo_state != Lo_unbound)
+ goto out_putf;
+
+ /* Avoid recursion */
+ f = file;
+ while (is_loop_device(f)) {
+ struct loop_device *l;
+
+ if (f->f_mapping->host->i_bdev == bdev)
+ goto out_putf;
+
+ l = f->f_mapping->host->i_bdev->bd_disk->private_data;
+ if (l->lo_state == Lo_unbound) {
+ error = -EINVAL;
+ goto out_putf;
+ }
+ f = l->lo_backing_file;
+ }
+
+ mapping = file->f_mapping;
+ inode = mapping->host;
+
+ error = -EINVAL;
+ if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
+ goto out_putf;
+
+ if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
+ !file->f_op->write_iter)
+ lo_flags |= LO_FLAGS_READ_ONLY;
+
+ lo_blocksize = S_ISBLK(inode->i_mode) ?
+ inode->i_bdev->bd_block_size : PAGE_SIZE;
+
+ error = -EFBIG;
+ size = get_loop_size(lo, file);
+ if ((loff_t)(sector_t)size != size)
+ goto out_putf;
+
+ error = 0;
+
+ set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
+
+ lo->lo_blocksize = lo_blocksize;
+ lo->lo_device = bdev;
+ lo->lo_flags = lo_flags;
+ lo->lo_backing_file = file;
+ lo->transfer = NULL;
+ lo->ioctl = NULL;
+ lo->lo_sizelimit = 0;
+ lo->old_gfp_mask = mapping_gfp_mask(mapping);
+ mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
+
+ if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
+ blk_queue_flush(lo->lo_queue, REQ_FLUSH);
+
+ set_capacity(lo->lo_disk, size);
+ bd_set_size(bdev, size << 9);
+ loop_sysfs_init(lo);
+ /* let user-space know about the new size */
+ kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
+
+ set_blocksize(bdev, lo_blocksize);
+
+ lo->lo_state = Lo_bound;
+ if (part_shift)
+ lo->lo_flags |= LO_FLAGS_PARTSCAN;
+ if (lo->lo_flags & LO_FLAGS_PARTSCAN)
+ ioctl_by_bdev(bdev, BLKRRPART, 0);
+
+ /* Grab the block_device to prevent its destruction after we
+ * put /dev/loopXX inode. Later in loop_clr_fd() we bdput(bdev).
+ */
+ bdgrab(bdev);
+ return 0;
+
+ out_putf:
+ fput(file);
+ out:
+ /* This is safe: open() is still holding a reference. */
+ module_put(THIS_MODULE);
+ return error;
+}
+
+static int
+loop_release_xfer(struct loop_device *lo)
+{
+ int err = 0;
+ struct loop_func_table *xfer = lo->lo_encryption;
+
+ if (xfer) {
+ if (xfer->release)
+ err = xfer->release(lo);
+ lo->transfer = NULL;
+ lo->lo_encryption = NULL;
+ module_put(xfer->owner);
+ }
+ return err;
+}
+
+static int
+loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
+ const struct loop_info64 *i)
+{
+ int err = 0;
+
+ if (xfer) {
+ struct module *owner = xfer->owner;
+
+ if (!try_module_get(owner))
+ return -EINVAL;
+ if (xfer->init)
+ err = xfer->init(lo, i);
+ if (err)
+ module_put(owner);
+ else
+ lo->lo_encryption = xfer;
+ }
+ return err;
+}
+
+static int loop_clr_fd(struct loop_device *lo)
+{
+ struct file *filp = lo->lo_backing_file;
+ gfp_t gfp = lo->old_gfp_mask;
+ struct block_device *bdev = lo->lo_device;
+
+ if (lo->lo_state != Lo_bound)
+ 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 (lo->lo_refcnt > 1) {
+ lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
+ mutex_unlock(&lo->lo_ctl_mutex);
+ return 0;
+ }
+
+ if (filp == NULL)
+ return -EINVAL;
+
+ spin_lock_irq(&lo->lo_lock);
+ lo->lo_state = Lo_rundown;
+ lo->lo_backing_file = NULL;
+ spin_unlock_irq(&lo->lo_lock);
+
+ loop_release_xfer(lo);
+ lo->transfer = NULL;
+ lo->ioctl = NULL;
+ lo->lo_device = NULL;
+ lo->lo_encryption = NULL;
+ lo->lo_offset = 0;
+ lo->lo_sizelimit = 0;
+ lo->lo_encrypt_key_size = 0;
+ memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
+ memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
+ memset(lo->lo_file_name, 0, LO_NAME_SIZE);
+ if (bdev) {
+ bdput(bdev);
+ invalidate_bdev(bdev);
+ }
+ set_capacity(lo->lo_disk, 0);
+ loop_sysfs_exit(lo);
+ if (bdev) {
+ bd_set_size(bdev, 0);
+ /* let user-space know about this change */
+ kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
+ }
+ mapping_set_gfp_mask(filp->f_mapping, gfp);
+ lo->lo_state = Lo_unbound;
+ /* This is safe: open() is still holding a reference. */
+ module_put(THIS_MODULE);
+ if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev)
+ ioctl_by_bdev(bdev, BLKRRPART, 0);
+ lo->lo_flags = 0;
+ if (!part_shift)
+ lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
+ mutex_unlock(&lo->lo_ctl_mutex);
+ /*
+ * Need not hold lo_ctl_mutex to fput backing file.
+ * Calling fput holding lo_ctl_mutex triggers a circular
+ * lock dependency possibility warning as fput can take
+ * bd_mutex which is usually taken before lo_ctl_mutex.
+ */
+ fput(filp);
+ return 0;
+}
+
+static int
+loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
+{
+ int err;
+ struct loop_func_table *xfer;
+ kuid_t uid = current_uid();
+
+ if (lo->lo_encrypt_key_size &&
+ !uid_eq(lo->lo_key_owner, uid) &&
+ !capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ if (lo->lo_state != Lo_bound)
+ return -ENXIO;
+ if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
+ return -EINVAL;
+
+ err = loop_release_xfer(lo);
+ if (err)
+ return err;
+
+ if (info->lo_encrypt_type) {
+ unsigned int type = info->lo_encrypt_type;
+
+ if (type >= MAX_LO_CRYPT)
+ return -EINVAL;
+ xfer = xfer_funcs[type];
+ if (xfer == NULL)
+ return -EINVAL;
+ } else
+ xfer = NULL;
+
+ err = loop_init_xfer(lo, xfer, info);
+ if (err)
+ return err;
+
+ if (lo->lo_offset != info->lo_offset ||
+ lo->lo_sizelimit != info->lo_sizelimit)
+ if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit))
+ return -EFBIG;
+
+ loop_config_discard(lo);
+
+ memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
+ memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
+ lo->lo_file_name[LO_NAME_SIZE-1] = 0;
+ lo->lo_crypt_name[LO_NAME_SIZE-1] = 0;
+
+ if (!xfer)
+ xfer = &none_funcs;
+ lo->transfer = xfer->transfer;
+ lo->ioctl = xfer->ioctl;
+
+ if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) !=
+ (info->lo_flags & LO_FLAGS_AUTOCLEAR))
+ lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;
+
+ if ((info->lo_flags & LO_FLAGS_PARTSCAN) &&
+ !(lo->lo_flags & LO_FLAGS_PARTSCAN)) {
+ lo->lo_flags |= LO_FLAGS_PARTSCAN;
+ lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
+ ioctl_by_bdev(lo->lo_device, BLKRRPART, 0);
+ }
+
+ lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
+ lo->lo_init[0] = info->lo_init[0];
+ lo->lo_init[1] = info->lo_init[1];
+ if (info->lo_encrypt_key_size) {
+ memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
+ info->lo_encrypt_key_size);
+ lo->lo_key_owner = uid;
+ }
+
+ return 0;
+}
+
+static int
+loop_get_status(struct loop_device *lo, struct loop_info64 *info)
+{
+ struct file *file = lo->lo_backing_file;
+ struct kstat stat;
+ int error;
+
+ if (lo->lo_state != Lo_bound)
+ return -ENXIO;
+ error = vfs_getattr(&file->f_path, &stat);
+ if (error)
+ return error;
+ memset(info, 0, sizeof(*info));
+ info->lo_number = lo->lo_number;
+ info->lo_device = huge_encode_dev(stat.dev);
+ info->lo_inode = stat.ino;
+ info->lo_rdevice = huge_encode_dev(lo->lo_device ? stat.rdev : stat.dev);
+ 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);
+ memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE);
+ info->lo_encrypt_type =
+ lo->lo_encryption ? lo->lo_encryption->number : 0;
+ if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
+ info->lo_encrypt_key_size = lo->lo_encrypt_key_size;
+ memcpy(info->lo_encrypt_key, lo->lo_encrypt_key,
+ lo->lo_encrypt_key_size);
+ }
+ return 0;
+}
+
+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_encrypt_type = info->lo_encrypt_type;
+ info64->lo_encrypt_key_size = info->lo_encrypt_key_size;
+ info64->lo_flags = info->lo_flags;
+ info64->lo_init[0] = info->lo_init[0];
+ info64->lo_init[1] = info->lo_init[1];
+ if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
+ memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE);
+ else
+ memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
+ memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_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_encrypt_type = info64->lo_encrypt_type;
+ info->lo_encrypt_key_size = info64->lo_encrypt_key_size;
+ info->lo_flags = info64->lo_flags;
+ info->lo_init[0] = info64->lo_init[0];
+ info->lo_init[1] = info64->lo_init[1];
+ if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
+ memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
+ else
+ memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
+ memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_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 = 0;
+
+ if (!arg)
+ err = -EINVAL;
+ if (!err)
+ 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 = 0;
+
+ if (!arg)
+ err = -EINVAL;
+ if (!err)
+ 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, struct block_device *bdev)
+{
+ if (unlikely(lo->lo_state != Lo_bound))
+ return -ENXIO;
+
+ return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit);
+}
+
+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;
+ int err;
+
+ mutex_lock_nested(&lo->lo_ctl_mutex, 1);
+ switch (cmd) {
+ case LOOP_SET_FD:
+ err = loop_set_fd(lo, mode, bdev, arg);
+ break;
+ case LOOP_CHANGE_FD:
+ err = loop_change_fd(lo, bdev, arg);
+ break;
+ case LOOP_CLR_FD:
+ /* loop_clr_fd would have unlocked lo_ctl_mutex on success */
+ err = loop_clr_fd(lo);
+ if (!err)
+ goto out_unlocked;
+ break;
+ case LOOP_SET_STATUS:
+ err = -EPERM;
+ if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
+ err = loop_set_status_old(lo,
+ (struct loop_info __user *)arg);
+ break;
+ case LOOP_GET_STATUS:
+ err = loop_get_status_old(lo, (struct loop_info __user *) arg);
+ break;
+ case LOOP_SET_STATUS64:
+ err = -EPERM;
+ if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
+ err = loop_set_status64(lo,
+ (struct loop_info64 __user *) arg);
+ break;
+ case LOOP_GET_STATUS64:
+ err = loop_get_status64(lo, (struct loop_info64 __user *) arg);
+ break;
+ case LOOP_SET_CAPACITY:
+ err = -EPERM;
+ if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
+ err = loop_set_capacity(lo, bdev);
+ break;
+ default:
+ err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
+ }
+ mutex_unlock(&lo->lo_ctl_mutex);
+
+out_unlocked:
+ 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;
+ 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_encrypt_type = info.lo_encrypt_type;
+ info64->lo_encrypt_key_size = info.lo_encrypt_key_size;
+ info64->lo_flags = info.lo_flags;
+ info64->lo_init[0] = info.lo_init[0];
+ info64->lo_init[1] = info.lo_init[1];
+ if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
+ memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE);
+ else
+ memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
+ memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_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_encrypt_type = info64->lo_encrypt_type;
+ info.lo_encrypt_key_size = info64->lo_encrypt_key_size;
+ info.lo_flags = info64->lo_flags;
+ info.lo_init[0] = info64->lo_init[0];
+ info.lo_init[1] = info64->lo_init[1];
+ if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
+ memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
+ else
+ memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
+ memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_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 ||
+ info.lo_init[0] != info64->lo_init[0] ||
+ info.lo_init[1] != info64->lo_init[1])
+ 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 = 0;
+
+ if (!arg)
+ err = -EINVAL;
+ if (!err)
+ 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:
+ mutex_lock(&lo->lo_ctl_mutex);
+ err = loop_set_status_compat(
+ lo, (const struct compat_loop_info __user *) arg);
+ mutex_unlock(&lo->lo_ctl_mutex);
+ break;
+ case LOOP_GET_STATUS:
+ mutex_lock(&lo->lo_ctl_mutex);
+ err = loop_get_status_compat(
+ lo, (struct compat_loop_info __user *) arg);
+ mutex_unlock(&lo->lo_ctl_mutex);
+ break;
+ case LOOP_SET_CAPACITY:
+ case LOOP_CLR_FD:
+ case LOOP_GET_STATUS64:
+ case LOOP_SET_STATUS64:
+ arg = (unsigned long) compat_ptr(arg);
+ case LOOP_SET_FD:
+ case LOOP_CHANGE_FD:
+ err = lo_ioctl(bdev, mode, cmd, arg);
+ break;
+ default:
+ err = -ENOIOCTLCMD;
+ break;
+ }
+ return err;
+}
+#endif
+
+static int lo_open(struct block_device *bdev, fmode_t mode)
+{
+ struct loop_device *lo;
+ int err = 0;
+
+ mutex_lock(&loop_index_mutex);
+ lo = bdev->bd_disk->private_data;
+ if (!lo) {
+ err = -ENXIO;
+ goto out;
+ }
+
+ mutex_lock(&lo->lo_ctl_mutex);
+ lo->lo_refcnt++;
+ mutex_unlock(&lo->lo_ctl_mutex);
+out:
+ mutex_unlock(&loop_index_mutex);
+ return err;
+}
+
+static void lo_release(struct gendisk *disk, fmode_t mode)
+{
+ struct loop_device *lo = disk->private_data;
+ int err;
+
+ mutex_lock(&lo->lo_ctl_mutex);
+
+ if (--lo->lo_refcnt)
+ goto out;
+
+ if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
+ /*
+ * In autoclear mode, stop the loop thread
+ * and remove configuration after last close.
+ */
+ err = loop_clr_fd(lo);
+ if (!err)
+ return;
+ } else {
+ /*
+ * Otherwise keep thread (if running) and config,
+ * but flush possible ongoing bios in thread.
+ */
+ loop_flush(lo);
+ }
+
+out:
+ mutex_unlock(&lo->lo_ctl_mutex);
+}
+
+static const struct block_device_operations lo_fops = {
+ .owner = THIS_MODULE,
+ .open = lo_open,
+ .release = lo_release,
+ .ioctl = lo_ioctl,
+#ifdef CONFIG_COMPAT
+ .compat_ioctl = lo_compat_ioctl,
+#endif
+};
+
+/*
+ * And now the modules code and kernel interface.
+ */
+static int max_loop;
+module_param(max_loop, int, S_IRUGO);
+MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
+module_param(max_part, int, S_IRUGO);
+MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
+
+int loop_register_transfer(struct loop_func_table *funcs)
+{
+ unsigned int n = funcs->number;
+
+ if (n >= MAX_LO_CRYPT || xfer_funcs[n])
+ return -EINVAL;
+ xfer_funcs[n] = funcs;
+ return 0;
+}
+
+static int unregister_transfer_cb(int id, void *ptr, void *data)
+{
+ struct loop_device *lo = ptr;
+ struct loop_func_table *xfer = data;
+
+ mutex_lock(&lo->lo_ctl_mutex);
+ if (lo->lo_encryption == xfer)
+ loop_release_xfer(lo);
+ mutex_unlock(&lo->lo_ctl_mutex);
+ return 0;
+}
+
+int loop_unregister_transfer(int number)
+{
+ unsigned int n = number;
+ struct loop_func_table *xfer;
+
+ if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
+ return -EINVAL;
+
+ xfer_funcs[n] = NULL;
+ idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer);
+ return 0;
+}
+
+EXPORT_SYMBOL(loop_register_transfer);
+EXPORT_SYMBOL(loop_unregister_transfer);
+
+static int loop_queue_rq(struct blk_mq_hw_ctx *hctx,
+ const struct blk_mq_queue_data *bd)
+{
+ struct loop_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);
+
+ blk_mq_start_request(bd->rq);
+
+ if (cmd->rq->cmd_flags & REQ_WRITE) {
+ struct loop_device *lo = cmd->rq->q->queuedata;
+ bool need_sched = true;
+
+ spin_lock_irq(&lo->lo_lock);
+ if (lo->write_started)
+ need_sched = false;
+ else
+ lo->write_started = true;
+ list_add_tail(&cmd->list, &lo->write_cmd_head);
+ spin_unlock_irq(&lo->lo_lock);
+
+ if (need_sched)
+ queue_work(loop_wq, &lo->write_work);
+ } else {
+ queue_work(loop_wq, &cmd->read_work);
+ }
+
+ return BLK_MQ_RQ_QUEUE_OK;
+}
+
+static void loop_handle_cmd(struct loop_cmd *cmd)
+{
+ const bool write = cmd->rq->cmd_flags & REQ_WRITE;
+ struct loop_device *lo = cmd->rq->q->queuedata;
+ int ret = -EIO;
+
+ if (lo->lo_state != Lo_bound)
+ goto failed;
+
+ if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY))
+ goto failed;
+
+ ret = do_req_filebacked(lo, cmd->rq);
+
+ failed:
+ if (ret)
+ cmd->rq->errors = -EIO;
+ blk_mq_complete_request(cmd->rq);
+}
+
+static void loop_queue_write_work(struct work_struct *work)
+{
+ struct loop_device *lo =
+ container_of(work, struct loop_device, write_work);
+ LIST_HEAD(cmd_list);
+
+ spin_lock_irq(&lo->lo_lock);
+ repeat:
+ list_splice_init(&lo->write_cmd_head, &cmd_list);
+ spin_unlock_irq(&lo->lo_lock);
+
+ while (!list_empty(&cmd_list)) {
+ struct loop_cmd *cmd = list_first_entry(&cmd_list,
+ struct loop_cmd, list);
+ list_del_init(&cmd->list);
+ loop_handle_cmd(cmd);
+ }
+
+ spin_lock_irq(&lo->lo_lock);
+ if (!list_empty(&lo->write_cmd_head))
+ goto repeat;
+ lo->write_started = false;
+ spin_unlock_irq(&lo->lo_lock);
+}
+
+static void loop_queue_read_work(struct work_struct *work)
+{
+ struct loop_cmd *cmd =
+ container_of(work, struct loop_cmd, read_work);
+
+ loop_handle_cmd(cmd);
+}
+
+static int loop_init_request(void *data, struct request *rq,
+ unsigned int hctx_idx, unsigned int request_idx,
+ unsigned int numa_node)
+{
+ struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
+
+ cmd->rq = rq;
+ INIT_WORK(&cmd->read_work, loop_queue_read_work);
+
+ return 0;
+}
+
+static struct blk_mq_ops loop_mq_ops = {
+ .queue_rq = loop_queue_rq,
+ .map_queue = blk_mq_map_queue,
+ .init_request = loop_init_request,
+};
+
+static int loop_add(struct loop_device **l, int i)
+{
+ struct loop_device *lo;
+ struct gendisk *disk;
+ int err;
+
+ err = -ENOMEM;
+ lo = kzalloc(sizeof(*lo), GFP_KERNEL);
+ if (!lo)
+ goto out;
+
+ lo->lo_state = Lo_unbound;
+
+ /* 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);
+ }
+ if (err < 0)
+ goto out_free_dev;
+ i = err;
+
+ err = -ENOMEM;
+ lo->tag_set.ops = &loop_mq_ops;
+ lo->tag_set.nr_hw_queues = 1;
+ lo->tag_set.queue_depth = 128;
+ 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_SG_MERGE;
+ lo->tag_set.driver_data = lo;
+
+ err = blk_mq_alloc_tag_set(&lo->tag_set);
+ if (err)
+ goto out_free_idr;
+
+ lo->lo_queue = blk_mq_init_queue(&lo->tag_set);
+ if (IS_ERR_OR_NULL(lo->lo_queue)) {
+ err = PTR_ERR(lo->lo_queue);
+ goto out_cleanup_tags;
+ }
+ lo->lo_queue->queuedata = lo;
+
+ INIT_LIST_HEAD(&lo->write_cmd_head);
+ INIT_WORK(&lo->write_work, loop_queue_write_work);
+
+ disk = lo->lo_disk = alloc_disk(1 << part_shift);
+ if (!disk)
+ goto out_free_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)
+ disk->flags |= GENHD_FL_NO_PART_SCAN;
+ disk->flags |= GENHD_FL_EXT_DEVT;
+ mutex_init(&lo->lo_ctl_mutex);
+ lo->lo_number = i;
+ spin_lock_init(&lo->lo_lock);
+ disk->major = LOOP_MAJOR;
+ disk->first_minor = i << part_shift;
+ disk->fops = &lo_fops;
+ disk->private_data = lo;
+ disk->queue = lo->lo_queue;
+ sprintf(disk->disk_name, "loop%d", i);
+ add_disk(disk);
+ *l = lo;
+ return lo->lo_number;
+
+out_free_queue:
+ blk_cleanup_queue(lo->lo_queue);
+out_cleanup_tags:
+ blk_mq_free_tag_set(&lo->tag_set);
+out_free_idr:
+ idr_remove(&loop_index_idr, i);
+out_free_dev:
+ kfree(lo);
+out:
+ return err;
+}
+
+static void loop_remove(struct loop_device *lo)
+{
+ blk_cleanup_queue(lo->lo_queue);
+ del_gendisk(lo->lo_disk);
+ blk_mq_free_tag_set(&lo->tag_set);
+ put_disk(lo->lo_disk);
+ kfree(lo);
+}
+
+static int find_free_cb(int id, void *ptr, void *data)
+{
+ struct loop_device *lo = ptr;
+ struct loop_device **l = data;
+
+ if (lo->lo_state == Lo_unbound) {
+ *l = lo;
+ return 1;
+ }
+ return 0;
+}
+
+static int loop_lookup(struct loop_device **l, int i)
+{
+ struct loop_device *lo;
+ int ret = -ENODEV;
+
+ if (i < 0) {
+ int err;
+
+ err = idr_for_each(&loop_index_idr, &find_free_cb, &lo);
+ if (err == 1) {
+ *l = lo;
+ ret = lo->lo_number;
+ }
+ goto out;
+ }
+
+ /* lookup and return a specific i */
+ lo = idr_find(&loop_index_idr, i);
+ if (lo) {
+ *l = lo;
+ ret = lo->lo_number;
+ }
+out:
+ return ret;
+}
+
+static struct kobject *loop_probe(dev_t dev, int *part, void *data)
+{
+ struct loop_device *lo;
+ struct kobject *kobj;
+ int err;
+
+ mutex_lock(&loop_index_mutex);
+ err = loop_lookup(&lo, MINOR(dev) >> part_shift);
+ if (err < 0)
+ err = loop_add(&lo, MINOR(dev) >> part_shift);
+ if (err < 0)
+ kobj = NULL;
+ else
+ kobj = get_disk(lo->lo_disk);
+ mutex_unlock(&loop_index_mutex);
+
+ *part = 0;
+ return kobj;
+}
+
+static long loop_control_ioctl(struct file *file, unsigned int cmd,
+ unsigned long parm)
+{
+ struct loop_device *lo;
+ int ret = -ENOSYS;
+
+ mutex_lock(&loop_index_mutex);
+ switch (cmd) {
+ case LOOP_CTL_ADD:
+ ret = loop_lookup(&lo, parm);
+ if (ret >= 0) {
+ ret = -EEXIST;
+ break;
+ }
+ ret = loop_add(&lo, parm);
+ break;
+ case LOOP_CTL_REMOVE:
+ ret = loop_lookup(&lo, parm);
+ if (ret < 0)
+ break;
+ mutex_lock(&lo->lo_ctl_mutex);
+ if (lo->lo_state != Lo_unbound) {
+ ret = -EBUSY;
+ mutex_unlock(&lo->lo_ctl_mutex);
+ break;
+ }
+ if (lo->lo_refcnt > 0) {
+ ret = -EBUSY;
+ mutex_unlock(&lo->lo_ctl_mutex);
+ break;
+ }
+ lo->lo_disk->private_data = NULL;
+ mutex_unlock(&lo->lo_ctl_mutex);
+ idr_remove(&loop_index_idr, lo->lo_number);
+ loop_remove(lo);
+ break;
+ case LOOP_CTL_GET_FREE:
+ ret = loop_lookup(&lo, -1);
+ if (ret >= 0)
+ break;
+ ret = loop_add(&lo, -1);
+ }
+ mutex_unlock(&loop_index_mutex);
+
+ return ret;
+}
+
+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, nr;
+ unsigned long range;
+ struct loop_device *lo;
+ int err;
+
+ err = misc_register(&loop_misc);
+ if (err < 0)
+ return 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 misc_out;
+ }
+
+ if (max_loop > 1UL << (MINORBITS - part_shift)) {
+ err = -EINVAL;
+ goto misc_out;
+ }
+
+ /*
+ * 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.
+ */
+ if (max_loop) {
+ nr = max_loop;
+ range = max_loop << part_shift;
+ } else {
+ nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
+ range = 1UL << MINORBITS;
+ }
+
+ if (register_blkdev(LOOP_MAJOR, "loop")) {
+ err = -EIO;
+ goto misc_out;
+ }
+
+ loop_wq = alloc_workqueue("kloopd",
+ WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 0);
+ if (!loop_wq) {
+ err = -ENOMEM;
+ goto misc_out;
+ }
+
+ blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
+ THIS_MODULE, loop_probe, NULL, NULL);
+
+ /* pre-create number of devices given by config or max_loop */
+ mutex_lock(&loop_index_mutex);
+ for (i = 0; i < nr; i++)
+ loop_add(&lo, i);
+ mutex_unlock(&loop_index_mutex);
+
+ printk(KERN_INFO "loop: module loaded\n");
+ return 0;
+
+misc_out:
+ misc_deregister(&loop_misc);
+ return err;
+}
+
+static int loop_exit_cb(int id, void *ptr, void *data)
+{
+ struct loop_device *lo = ptr;
+
+ loop_remove(lo);
+ return 0;
+}
+
+static void __exit loop_exit(void)
+{
+ unsigned long range;
+
+ range = max_loop ? max_loop << part_shift : 1UL << MINORBITS;
+
+ idr_for_each(&loop_index_idr, &loop_exit_cb, NULL);
+ idr_destroy(&loop_index_idr);
+
+ blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
+ unregister_blkdev(LOOP_MAJOR, "loop");
+
+ destroy_workqueue(loop_wq);
+
+ misc_deregister(&loop_misc);
+}
+
+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
Code Review / kvmfornfv.git / blobdiff