diff options
Diffstat (limited to 'drivers/block/loop.c')
| -rw-r--r-- | drivers/block/loop.c | 2309 |
1 files changed, 2309 insertions, 0 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c new file mode 100644 index 000000000..c31a76485 --- /dev/null +++ b/drivers/block/loop.c @@ -0,0 +1,2309 @@ +/* + * 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 <linux/ioprio.h> + +#include "loop.h" + +#include <linux/uaccess.h> + +static DEFINE_IDR(loop_index_idr); +static DEFINE_MUTEX(loop_ctl_mutex); + +static int max_part; +static int part_shift; + +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 void __loop_update_dio(struct loop_device *lo, bool dio) +{ + struct file *file = lo->lo_backing_file; + struct address_space *mapping = file->f_mapping; + struct inode *inode = mapping->host; + unsigned short sb_bsize = 0; + unsigned dio_align = 0; + bool use_dio; + + if (inode->i_sb->s_bdev) { + sb_bsize = bdev_logical_block_size(inode->i_sb->s_bdev); + dio_align = sb_bsize - 1; + } + + /* + * We support direct I/O only if lo_offset is aligned with the + * logical I/O size of backing device, and the logical block + * size of loop is bigger than the backing device's and the loop + * needn't transform transfer. + * + * TODO: the above condition may be loosed in the future, and + * direct I/O may be switched runtime at that time because most + * of requests in sane applications should be PAGE_SIZE aligned + */ + if (dio) { + if (queue_logical_block_size(lo->lo_queue) >= sb_bsize && + !(lo->lo_offset & dio_align) && + mapping->a_ops->direct_IO && + !lo->transfer) + use_dio = true; + else + use_dio = false; + } else { + use_dio = false; + } + + if (lo->use_dio == use_dio) + return; + + /* flush dirty pages before changing direct IO */ + vfs_fsync(file, 0); + + /* + * The flag of LO_FLAGS_DIRECT_IO is handled similarly with + * LO_FLAGS_READ_ONLY, both are set from kernel, and losetup + * will get updated by ioctl(LOOP_GET_STATUS) + */ + 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; + } + blk_mq_unfreeze_queue(lo->lo_queue); +} + +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 | WRITE, 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; +} + +/* + * 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, 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_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, 0); + 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_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. However we do not support this if + * encryption is enabled, because it may give an attacker useful + * information. + */ + struct file *file = lo->lo_backing_file; + struct request_queue *q = lo->lo_queue; + int ret; + + mode |= FALLOC_FL_KEEP_SIZE; + + if (!blk_queue_discard(q)) { + 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 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 = BLK_STS_IOERR; + 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; + blk_mq_complete_request(rq); +} + +static void lo_rw_aio_complete(struct kiocb *iocb, long ret, long ret2) +{ + struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb); + + if (cmd->css) + css_put(cmd->css); + 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, bool rw) +{ + struct iov_iter 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; + unsigned int offset; + int segments = 0; + int ret; + + if (rq->bio != rq->biotail) { + struct req_iterator iter; + struct bio_vec tmp; + + __rq_for_each_bio(bio, rq) + segments += bio_segments(bio); + bvec = kmalloc_array(segments, 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_segment + * API will take care of all details for us. + */ + rq_for_each_segment(tmp, 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); + segments = bio_segments(bio); + } + atomic_set(&cmd->ref, 2); + + iov_iter_bvec(&iter, ITER_BVEC | rw, bvec, + segments, 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 (cmd->css) + kthread_associate_blkcg(cmd->css); + + if (rw == WRITE) + ret = call_write_iter(file, &cmd->iocb, &iter); + else + ret = call_read_iter(file, &cmd->iocb, &iter); + + lo_rw_aio_do_completion(cmd); + kthread_associate_blkcg(NULL); + + if (ret != -EIOCBQUEUED) + cmd->iocb.ki_complete(&cmd->iocb, ret, 0); + 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 (lo->transfer) + return lo_write_transfer(lo, rq, pos); + else if (cmd->use_aio) + return lo_rw_aio(lo, cmd, pos, WRITE); + else + return lo_write_simple(lo, rq, pos); + case REQ_OP_READ: + if (lo->transfer) + return lo_read_transfer(lo, rq, pos); + else if (cmd->use_aio) + return lo_rw_aio(lo, cmd, pos, READ); + else + return lo_read_simple(lo, rq, pos); + default: + WARN_ON_ONCE(1); + return -EIO; + break; + } +} + +static inline void loop_update_dio(struct loop_device *lo) +{ + __loop_update_dio(lo, io_is_direct(lo->lo_backing_file) | + lo->use_dio); +} + +static void loop_reread_partitions(struct loop_device *lo, + struct block_device *bdev) +{ + int rc; + + rc = blkdev_reread_part(bdev); + 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) && MAJOR(i->i_rdev) == 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; + + if (f->f_mapping->host->i_bdev == bdev) + return -EBADF; + + l = f->f_mapping->host->i_bdev->bd_disk->private_data; + if (l->lo_state != Lo_bound) { + return -EINVAL; + } + 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 = NULL, *old_file; + int error; + bool partscan; + + error = mutex_lock_killable(&loop_ctl_mutex); + if (error) + return error; + 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 = -EBADF; + file = fget(arg); + if (!file) + 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 */ + 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; + mutex_unlock(&loop_ctl_mutex); + /* + * We must drop file reference outside of loop_ctl_mutex as dropping + * the file ref can take bd_mutex which creates circular locking + * dependency. + */ + fput(old_file); + if (partscan) + loop_reread_partitions(lo, bdev); + return 0; + +out_err: + mutex_unlock(&loop_ctl_mutex); + if (file) + fput(file); + return error; +} + +/* 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) && !lo->lo_encrypt_key_size) { + struct request_queue *backingq; + + backingq = bdev_get_queue(inode->i_bdev); + + max_discard_sectors = backingq->limits.max_write_zeroes_sectors; + granularity = backingq->limits.discard_granularity ?: + queue_physical_block_size(backingq); + + /* + * 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. + */ + } else if (!file->f_op->fallocate || lo->lo_encrypt_key_size) { + max_discard_sectors = 0; + granularity = 0; + + } else { + max_discard_sectors = UINT_MAX >> 9; + granularity = inode->i_sb->s_blocksize; + } + + 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); + blk_queue_flag_set(QUEUE_FLAG_DISCARD, q); + } else { + q->limits.discard_granularity = 0; + blk_queue_max_discard_sectors(q, 0); + blk_queue_max_write_zeroes_sectors(q, 0); + blk_queue_flag_clear(QUEUE_FLAG_DISCARD, q); + } + q->limits.discard_alignment = 0; +} + +static void loop_unprepare_queue(struct loop_device *lo) +{ + kthread_flush_worker(&lo->worker); + kthread_stop(lo->worker_task); +} + +static int loop_kthread_worker_fn(void *worker_ptr) +{ + current->flags |= PF_LESS_THROTTLE | PF_MEMALLOC_NOIO; + return kthread_worker_fn(worker_ptr); +} + +static int loop_prepare_queue(struct loop_device *lo) +{ + kthread_init_worker(&lo->worker); + lo->worker_task = kthread_run(loop_kthread_worker_fn, + &lo->worker, "loop%d", lo->lo_number); + if (IS_ERR(lo->worker_task)) + return -ENOMEM; + set_user_nice(lo->worker_task, MIN_NICE); + return 0; +} + +static int loop_set_fd(struct loop_device *lo, fmode_t mode, + struct block_device *bdev, unsigned int arg) +{ + struct file *file; + struct inode *inode; + struct address_space *mapping; + int lo_flags = 0; + int error; + loff_t size; + bool partscan; + + /* This is safe, since we have a reference from open(). */ + __module_get(THIS_MODULE); + + error = -EBADF; + file = fget(arg); + if (!file) + goto out; + + error = mutex_lock_killable(&loop_ctl_mutex); + if (error) + goto out_putf; + + 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 (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) || + !file->f_op->write_iter) + lo_flags |= LO_FLAGS_READ_ONLY; + + error = -EFBIG; + size = get_loop_size(lo, file); + if ((loff_t)(sector_t)size != size) + goto out_unlock; + error = loop_prepare_queue(lo); + if (error) + goto out_unlock; + + error = 0; + + set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0); + + lo->use_dio = false; + 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_write_cache(lo->lo_queue, true, false); + + loop_update_dio(lo); + 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, S_ISBLK(inode->i_mode) ? + block_size(inode->i_bdev) : PAGE_SIZE); + + lo->lo_state = Lo_bound; + if (part_shift) + lo->lo_flags |= LO_FLAGS_PARTSCAN; + partscan = lo->lo_flags & LO_FLAGS_PARTSCAN; + + /* Grab the block_device to prevent its destruction after we + * put /dev/loopXX inode. Later in __loop_clr_fd() we bdput(bdev). + */ + bdgrab(bdev); + mutex_unlock(&loop_ctl_mutex); + if (partscan) + loop_reread_partitions(lo, bdev); + return 0; + +out_unlock: + mutex_unlock(&loop_ctl_mutex); +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, bool release) +{ + struct file *filp = NULL; + gfp_t gfp = lo->old_gfp_mask; + struct block_device *bdev = lo->lo_device; + int err = 0; + bool partscan = false; + int lo_number; + + mutex_lock(&loop_ctl_mutex); + if (WARN_ON_ONCE(lo->lo_state != Lo_rundown)) { + err = -ENXIO; + goto out_unlock; + } + + filp = lo->lo_backing_file; + if (filp == NULL) { + err = -EINVAL; + goto out_unlock; + } + + /* freeze request queue during the transition */ + blk_mq_freeze_queue(lo->lo_queue); + + spin_lock_irq(&lo->lo_lock); + 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); + 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); + if (bdev) { + bdput(bdev); + invalidate_bdev(bdev); + bdev->bd_inode->i_mapping->wb_err = 0; + } + 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); + /* This is safe: open() is still holding a reference. */ + module_put(THIS_MODULE); + blk_mq_unfreeze_queue(lo->lo_queue); + + partscan = lo->lo_flags & LO_FLAGS_PARTSCAN && bdev; + lo_number = lo->lo_number; + loop_unprepare_queue(lo); +out_unlock: + mutex_unlock(&loop_ctl_mutex); + if (partscan) { + /* + * bd_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) + err = __blkdev_reread_part(bdev); + else + err = blkdev_reread_part(bdev); + if (err) + pr_warn("%s: partition scan of loop%d failed (rc=%d)\n", + __func__, lo_number, err); + /* Device is gone, no point in returning error */ + err = 0; + } + + /* + * 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->lo_backing_file is already cleared and Lo_rundown state + * protects us from all the other places trying to change the 'lo' + * device. + */ + mutex_lock(&loop_ctl_mutex); + lo->lo_flags = 0; + if (!part_shift) + lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN; + lo->lo_state = Lo_unbound; + mutex_unlock(&loop_ctl_mutex); + + /* + * Need not hold loop_ctl_mutex to fput backing file. + * Calling fput holding loop_ctl_mutex triggers a circular + * lock dependency possibility warning as fput can take + * bd_mutex which is usually taken before loop_ctl_mutex. + */ + if (filp) + fput(filp); + return err; +} + +static int loop_clr_fd(struct loop_device *lo) +{ + int err; + + err = mutex_lock_killable(&loop_ctl_mutex); + if (err) + return err; + if (lo->lo_state != Lo_bound) { + mutex_unlock(&loop_ctl_mutex); + 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 (atomic_read(&lo->lo_refcnt) > 1) { + lo->lo_flags |= LO_FLAGS_AUTOCLEAR; + mutex_unlock(&loop_ctl_mutex); + return 0; + } + lo->lo_state = Lo_rundown; + mutex_unlock(&loop_ctl_mutex); + + return __loop_clr_fd(lo, false); +} + +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(); + struct block_device *bdev; + bool partscan = false; + + err = mutex_lock_killable(&loop_ctl_mutex); + if (err) + return err; + if (lo->lo_encrypt_key_size && + !uid_eq(lo->lo_key_owner, uid) && + !capable(CAP_SYS_ADMIN)) { + err = -EPERM; + goto out_unlock; + } + if (lo->lo_state != Lo_bound) { + err = -ENXIO; + goto out_unlock; + } + if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE) { + err = -EINVAL; + goto out_unlock; + } + + if (lo->lo_offset != info->lo_offset || + lo->lo_sizelimit != info->lo_sizelimit) { + 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); + + err = loop_release_xfer(lo); + if (err) + goto out_unfreeze; + + if (info->lo_encrypt_type) { + unsigned int type = info->lo_encrypt_type; + + if (type >= MAX_LO_CRYPT) { + err = -EINVAL; + goto out_unfreeze; + } + xfer = xfer_funcs[type]; + if (xfer == NULL) { + err = -EINVAL; + goto out_unfreeze; + } + } else + xfer = NULL; + + err = loop_init_xfer(lo, xfer, info); + if (err) + goto out_unfreeze; + + if (lo->lo_offset != info->lo_offset || + lo->lo_sizelimit != info->lo_sizelimit) { + /* kill_bdev should have truncated all the pages */ + if (lo->lo_device->bd_inode->i_mapping->nrpages) { + err = -EAGAIN; + pr_warn("%s: loop%d (%s) has still dirty pages (nrpages=%lu)\n", + __func__, lo->lo_number, lo->lo_file_name, + lo->lo_device->bd_inode->i_mapping->nrpages); + goto out_unfreeze; + } + if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit)) { + err = -EFBIG; + goto out_unfreeze; + } + } + + 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; + + 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; + } + + /* 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 && (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; + bdev = lo->lo_device; + partscan = true; + } +out_unlock: + mutex_unlock(&loop_ctl_mutex); + if (partscan) + loop_reread_partitions(lo, bdev); + + 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(&loop_ctl_mutex); + if (ret) + return ret; + if (lo->lo_state != Lo_bound) { + mutex_unlock(&loop_ctl_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); + 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); + } + + /* Drop loop_ctl_mutex while we call into the filesystem. */ + path = lo->lo_backing_file->f_path; + path_get(&path); + mutex_unlock(&loop_ctl_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_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; + + 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) +{ + if (unlikely(lo->lo_state != Lo_bound)) + return -ENXIO; + + return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit); +} + +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; + + if (arg < 512 || arg > PAGE_SIZE || !is_power_of_2(arg)) + return -EINVAL; + + if (lo->lo_queue->limits.logical_block_size != arg) { + sync_blockdev(lo->lo_device); + invalidate_bdev(lo->lo_device); + } + + blk_mq_freeze_queue(lo->lo_queue); + + /* invalidate_bdev should have truncated all the pages */ + if (lo->lo_queue->limits.logical_block_size != arg && + lo->lo_device->bd_inode->i_mapping->nrpages) { + err = -EAGAIN; + pr_warn("%s: loop%d (%s) has still dirty pages (nrpages=%lu)\n", + __func__, lo->lo_number, lo->lo_file_name, + lo->lo_device->bd_inode->i_mapping->nrpages); + goto out_unfreeze; + } + + 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); +out_unfreeze: + 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(&loop_ctl_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 = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL; + } + mutex_unlock(&loop_ctl_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; + int err; + + switch (cmd) { + case LOOP_SET_FD: + return loop_set_fd(lo, mode, bdev, arg); + 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, + (struct loop_info __user *)arg); + } + break; + case LOOP_GET_STATUS: + return loop_get_status_old(lo, (struct loop_info __user *) arg); + 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: + return loop_get_status64(lo, (struct loop_info64 __user *) arg); + case LOOP_SET_CAPACITY: + case LOOP_SET_DIRECT_IO: + case LOOP_SET_BLOCK_SIZE: + if (!(mode & FMODE_WRITE) && !capable(CAP_SYS_ADMIN)) + return -EPERM; + /* Fall through */ + 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; + 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; + + 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: + arg = (unsigned long) compat_ptr(arg); + /* fall through */ + 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 int lo_open(struct block_device *bdev, fmode_t mode) +{ + struct loop_device *lo; + int err; + + err = mutex_lock_killable(&loop_ctl_mutex); + if (err) + return err; + lo = bdev->bd_disk->private_data; + if (!lo) { + err = -ENXIO; + goto out; + } + + atomic_inc(&lo->lo_refcnt); +out: + mutex_unlock(&loop_ctl_mutex); + return err; +} + +static void lo_release(struct gendisk *disk, fmode_t mode) +{ + struct loop_device *lo; + + mutex_lock(&loop_ctl_mutex); + lo = disk->private_data; + if (atomic_dec_return(&lo->lo_refcnt)) + goto out_unlock; + + if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) { + if (lo->lo_state != Lo_bound) + goto out_unlock; + lo->lo_state = Lo_rundown; + mutex_unlock(&loop_ctl_mutex); + /* + * In autoclear mode, stop the loop thread + * and remove configuration after last close. + */ + __loop_clr_fd(lo, true); + return; + } else if (lo->lo_state == Lo_bound) { + /* + * Otherwise keep thread (if running) and config, + * but flush possible ongoing bios in thread. + */ + blk_mq_freeze_queue(lo->lo_queue); + blk_mq_unfreeze_queue(lo->lo_queue); + } + +out_unlock: + mutex_unlock(&loop_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, 0444); +MODULE_PARM_DESC(max_loop, "Maximum number of loop devices"); +module_param(max_part, int, 0444); +MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device"); +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(&loop_ctl_mutex); + if (lo->lo_encryption == xfer) + loop_release_xfer(lo); + mutex_unlock(&loop_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 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 */ +#ifdef CONFIG_BLK_CGROUP + if (cmd->use_aio && rq->bio && rq->bio->bi_css) { + cmd->css = rq->bio->bi_css; + css_get(cmd->css); + } else +#endif + cmd->css = NULL; + kthread_queue_work(&lo->worker, &cmd->work); + + return BLK_STS_OK; +} + +static void loop_handle_cmd(struct loop_cmd *cmd) +{ + 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; + + if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) { + ret = -EIO; + goto failed; + } + + ret = do_req_filebacked(lo, rq); + failed: + /* complete non-aio request */ + if (!cmd->use_aio || ret) { + cmd->ret = ret ? -EIO : 0; + blk_mq_complete_request(rq); + } +} + +static void loop_queue_work(struct kthread_work *work) +{ + struct loop_cmd *cmd = + container_of(work, struct loop_cmd, work); + + loop_handle_cmd(cmd); +} + +static int loop_init_request(struct blk_mq_tag_set *set, struct request *rq, + unsigned int hctx_idx, unsigned int numa_node) +{ + struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); + + kthread_init_work(&cmd->work, loop_queue_work); + return 0; +} + +static const struct blk_mq_ops loop_mq_ops = { + .queue_rq = loop_queue_rq, + .init_request = loop_init_request, + .complete = lo_complete_rq, +}; + +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; + + 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); + + err = -ENOMEM; + 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; + atomic_set(&lo->lo_refcnt, 0); + 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) +{ + del_gendisk(lo->lo_disk); + blk_cleanup_queue(lo->lo_queue); + 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_ctl_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_and_module(lo->lo_disk); + mutex_unlock(&loop_ctl_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; + + ret = mutex_lock_killable(&loop_ctl_mutex); + if (ret) + return ret; + + ret = -ENOSYS; + 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; + if (lo->lo_state != Lo_unbound) { + ret = -EBUSY; + break; + } + if (atomic_read(&lo->lo_refcnt) > 0) { + ret = -EBUSY; + break; + } + lo->lo_disk->private_data = NULL; + 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_ctl_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; + + 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; + } + + /* + * 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; + } + + err = misc_register(&loop_misc); + if (err < 0) + goto err_out; + + + if (register_blkdev(LOOP_MAJOR, "loop")) { + err = -EIO; + 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_ctl_mutex); + for (i = 0; i < nr; i++) + loop_add(&lo, i); + mutex_unlock(&loop_ctl_mutex); + + printk(KERN_INFO "loop: module loaded\n"); + return 0; + +misc_out: + misc_deregister(&loop_misc); +err_out: + 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; + + mutex_lock(&loop_ctl_mutex); + + 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"); + + misc_deregister(&loop_misc); + + mutex_unlock(&loop_ctl_mutex); +} + +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 |