/* * 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/loop.h> #include <linux/compat.h> #include <linux/suspend.h> #include <linux/freezer.h> #include <linux/mutex.h> #include <linux/writeback.h> #include <linux/buffer_head.h> /* for invalidate_bdev() */ #include <linux/completion.h> #include <linux/highmem.h> #include <linux/kthread.h> #include <linux/splice.h> #include <linux/sysfs.h> #include <asm/uaccess.h> static LIST_HEAD(loop_devices); static DEFINE_MUTEX(loop_devices_mutex); static int max_part; static int part_shift; /* * Transfer functions */ static int transfer_none(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, KM_USER0) + raw_off; char *loop_buf = kmap_atomic(loop_page, KM_USER1) + loop_off; if (cmd == READ) memcpy(loop_buf, raw_buf, size); else memcpy(raw_buf, loop_buf, size); kunmap_atomic(loop_buf, KM_USER1); kunmap_atomic(raw_buf, KM_USER0); cond_resched(); return 0; } 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, KM_USER0) + raw_off; char *loop_buf = kmap_atomic(loop_page, KM_USER1) + 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, KM_USER1); kunmap_atomic(raw_buf, KM_USER0); 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, .transfer = transfer_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_loop_size(struct loop_device *lo, struct file *file) { loff_t size, offset, loopsize; /* Compute loopsize in bytes */ size = i_size_read(file->f_mapping->host); offset = lo->lo_offset; loopsize = size - offset; if (lo->lo_sizelimit > 0 && lo->lo_sizelimit < loopsize) loopsize = lo->lo_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 int figure_loop_size(struct loop_device *lo) { loff_t size = get_loop_size(lo, lo->lo_backing_file); sector_t x = (sector_t)size; if (unlikely((loff_t)x != size)) return -EFBIG; set_capacity(lo->lo_disk, x); 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) { if (unlikely(!lo->transfer)) return 0; return lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock); } /** * do_lo_send_aops - helper for writing data to a loop device * * This is the fast version for backing filesystems which implement the address * space operations write_begin and write_end. */ static int do_lo_send_aops(struct loop_device *lo, struct bio_vec *bvec, loff_t pos, struct page *unused) { struct file *file = lo->lo_backing_file; /* kudos to NFsckingS */ struct address_space *mapping = file->f_mapping; pgoff_t index; unsigned offset, bv_offs; int len, ret; mutex_lock(&mapping->host->i_mutex); index = pos >> PAGE_CACHE_SHIFT; offset = pos & ((pgoff_t)PAGE_CACHE_SIZE - 1); bv_offs = bvec->bv_offset; len = bvec->bv_len; while (len > 0) { sector_t IV; unsigned size, copied; int transfer_result; struct page *page; void *fsdata; IV = ((sector_t)index << (PAGE_CACHE_SHIFT - 9))+(offset >> 9); size = PAGE_CACHE_SIZE - offset; if (size > len) size = len; ret = pagecache_write_begin(file, mapping, pos, size, 0, &page, &fsdata); if (ret) goto fail; file_update_time(file); transfer_result = lo_do_transfer(lo, WRITE, page, offset, bvec->bv_page, bv_offs, size, IV); copied = size; if (unlikely(transfer_result)) copied = 0; ret = pagecache_write_end(file, mapping, pos, size, copied, page, fsdata); if (ret < 0 || ret != copied) goto fail; if (unlikely(transfer_result)) goto fail; bv_offs += copied; len -= copied; offset = 0; index++; pos += copied; } ret = 0; out: mutex_unlock(&mapping->host->i_mutex); return ret; fail: ret = -1; goto out; } /** * __do_lo_send_write - helper for writing data to a loop device * * This helper just factors out common code between do_lo_send_direct_write() * and do_lo_send_write(). */ static int __do_lo_send_write(struct file *file, u8 *buf, const int len, loff_t pos) { ssize_t bw; mm_segment_t old_fs = get_fs(); set_fs(get_ds()); bw = file->f_op->write(file, buf, len, &pos); set_fs(old_fs); if (likely(bw == len)) return 0; printk(KERN_ERR "loop: Write error at byte offset %llu, length %i.\n", (unsigned long long)pos, len); if (bw >= 0) bw = -EIO; return bw; } /** * do_lo_send_direct_write - helper for writing data to a loop device * * This is the fast, non-transforming version for backing filesystems which do * not implement the address space operations write_begin and write_end. * It uses the write file operation which should be present on all writeable * filesystems. */ static int do_lo_send_direct_write(struct loop_device *lo, struct bio_vec *bvec, loff_t pos, struct page *page) { ssize_t bw = __do_lo_send_write(lo->lo_backing_file, kmap(bvec->bv_page) + bvec->bv_offset, bvec->bv_len, pos); kunmap(bvec->bv_page); cond_resched(); return bw; } /** * do_lo_send_write - helper for writing data to a loop device * * This is the slow, transforming version for filesystems which do not * implement the address space operations write_begin and write_end. It * uses the write file operation which should be present on all writeable * filesystems. * * Using fops->write is slower than using aops->{prepare,commit}_write in the * transforming case because we need to double buffer the data as we cannot do * the transformations in place as we do not have direct access to the * destination pages of the backing file. */ static int do_lo_send_write(struct loop_device *lo, struct bio_vec *bvec, loff_t pos, struct page *page) { int ret = lo_do_transfer(lo, WRITE, page, 0, bvec->bv_page, bvec->bv_offset, bvec->bv_len, pos >> 9); if (likely(!ret)) return __do_lo_send_write(lo->lo_backing_file, page_address(page), bvec->bv_len, pos); printk(KERN_ERR "loop: Transfer error at byte offset %llu, " "length %i.\n", (unsigned long long)pos, bvec->bv_len); if (ret > 0) ret = -EIO; return ret; } static int lo_send(struct loop_device *lo, struct bio *bio, loff_t pos) { int (*do_lo_send)(struct loop_device *, struct bio_vec *, loff_t, struct page *page); struct bio_vec *bvec; struct page *page = NULL; int i, ret = 0; do_lo_send = do_lo_send_aops; if (!(lo->lo_flags & LO_FLAGS_USE_AOPS)) { do_lo_send = do_lo_send_direct_write; if (lo->transfer != transfer_none) { page = alloc_page(GFP_NOIO | __GFP_HIGHMEM); if (unlikely(!page)) goto fail; kmap(page); do_lo_send = do_lo_send_write; } } bio_for_each_segment(bvec, bio, i) { ret = do_lo_send(lo, bvec, pos, page); if (ret < 0) break; pos += bvec->bv_len; } if (page) { kunmap(page); __free_page(page); } out: return ret; fail: printk(KERN_ERR "loop: Failed to allocate temporary page for write.\n"); ret = -ENOMEM; goto out; } struct lo_read_data { struct loop_device *lo; struct page *page; unsigned offset; int bsize; }; static int lo_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf, struct splice_desc *sd) { struct lo_read_data *p = sd->u.data; struct loop_device *lo = p->lo; struct page *page = buf->page; sector_t IV; int size; IV = ((sector_t) page->index << (PAGE_CACHE_SHIFT - 9)) + (buf->offset >> 9); size = sd->len; if (size > p->bsize) size = p->bsize; if (lo_do_transfer(lo, READ, page, buf->offset, p->page, p->offset, size, IV)) { printk(KERN_ERR "loop: transfer error block %ld\n", page->index); size = -EINVAL; } flush_dcache_page(p->page); if (size > 0) p->offset += size; return size; } static int lo_direct_splice_actor(struct pipe_inode_info *pipe, struct splice_desc *sd) { return __splice_from_pipe(pipe, sd, lo_splice_actor); } static int do_lo_receive(struct loop_device *lo, struct bio_vec *bvec, int bsize, loff_t pos) { struct lo_read_data cookie; struct splice_desc sd; struct file *file; long retval; cookie.lo = lo; cookie.page = bvec->bv_page; cookie.offset = bvec->bv_offset; cookie.bsize = bsize; sd.len = 0; sd.total_len = bvec->bv_len; sd.flags = 0; sd.pos = pos; sd.u.data = &cookie; file = lo->lo_backing_file; retval = splice_direct_to_actor(file, &sd, lo_direct_splice_actor); if (retval < 0) return retval; return 0; } static int lo_receive(struct loop_device *lo, struct bio *bio, int bsize, loff_t pos) { struct bio_vec *bvec; int i, ret = 0; bio_for_each_segment(bvec, bio, i) { ret = do_lo_receive(lo, bvec, bsize, pos); if (ret < 0) break; pos += bvec->bv_len; } return ret; } static int do_bio_filebacked(struct loop_device *lo, struct bio *bio) { loff_t pos; int ret; pos = ((loff_t) bio->bi_sector << 9) + lo->lo_offset; if (bio_rw(bio) == WRITE) { struct file *file = lo->lo_backing_file; if (bio->bi_rw & REQ_FLUSH) { ret = vfs_fsync(file, 0); if (unlikely(ret && ret != -EINVAL)) { ret = -EIO; goto out; } } ret = lo_send(lo, bio, pos); if ((bio->bi_rw & REQ_FUA) && !ret) { ret = vfs_fsync(file, 0); if (unlikely(ret && ret != -EINVAL)) ret = -EIO; } } else ret = lo_receive(lo, bio, lo->lo_blocksize, pos); out: return ret; } /* * Add bio to back of pending list */ static void loop_add_bio(struct loop_device *lo, struct bio *bio) { bio_list_add(&lo->lo_bio_list, bio); } /* * Grab first pending buffer */ static struct bio *loop_get_bio(struct loop_device *lo) { return bio_list_pop(&lo->lo_bio_list); } static int loop_make_request(struct request_queue *q, struct bio *old_bio) { struct loop_device *lo = q->queuedata; int rw = bio_rw(old_bio); if (rw == READA) rw = READ; BUG_ON(!lo || (rw != READ && rw != WRITE)); spin_lock_irq(&lo->lo_lock); if (lo->lo_state != Lo_bound) goto out; if (unlikely(rw == WRITE && (lo->lo_flags & LO_FLAGS_READ_ONLY))) goto out; loop_add_bio(lo, old_bio); wake_up(&lo->lo_event); spin_unlock_irq(&lo->lo_lock); return 0; out: spin_unlock_irq(&lo->lo_lock); bio_io_error(old_bio); return 0; } /* * kick off io on the underlying address space */ static void loop_unplug(struct request_queue *q) { struct loop_device *lo = q->queuedata; queue_flag_clear_unlocked(QUEUE_FLAG_PLUGGED, q); blk_run_address_space(lo->lo_backing_file->f_mapping); } struct switch_request { struct file *file; struct completion wait; }; static void do_loop_switch(struct loop_device *, struct switch_request *); static inline void loop_handle_bio(struct loop_device *lo, struct bio *bio) { if (unlikely(!bio->bi_bdev)) { do_loop_switch(lo, bio->bi_private); bio_put(bio); } else { int ret = do_bio_filebacked(lo, bio); bio_endio(bio, ret); } } /* * worker thread that handles reads/writes to file backed loop devices, * to avoid blocking in our make_request_fn. it also does loop decrypting * on reads for block backed loop, as that is too heavy to do from * b_end_io context where irqs may be disabled. * * Loop explanation: loop_clr_fd() sets lo_state to Lo_rundown before * calling kthread_stop(). Therefore once kthread_should_stop() is * true, make_request will not place any more requests. Therefore * once kthread_should_stop() is true and lo_bio is NULL, we are * done with the loop. */ static int loop_thread(void *data) { struct loop_device *lo = data; struct bio *bio; set_user_nice(current, -20); while (!kthread_should_stop() || !bio_list_empty(&lo->lo_bio_list)) { wait_event_interruptible(lo->lo_event, !bio_list_empty(&lo->lo_bio_list) || kthread_should_stop()); if (bio_list_empty(&lo->lo_bio_list)) continue; spin_lock_irq(&lo->lo_lock); bio = loop_get_bio(lo); spin_unlock_irq(&lo->lo_lock); BUG_ON(!bio); loop_handle_bio(lo, bio); } return 0; } /* * 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; struct bio *bio = bio_alloc(GFP_KERNEL, 0); if (!bio) return -ENOMEM; init_completion(&w.wait); w.file = file; bio->bi_private = &w; bio->bi_bdev = NULL; loop_make_request(lo->lo_queue, bio); wait_for_completion(&w.wait); return 0; } /* * Helper to flush the IOs in loop, but keeping loop thread running */ static int loop_flush(struct loop_device *lo) { /* loop not yet configured, no running thread, nothing to flush */ if (!lo->lo_thread) return 0; return loop_switch(lo, NULL); } /* * 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) goto out; 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)); out: complete(&p->wait); } /* * 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 (max_part > 0) 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 loop_device *l, *lo = NULL; mutex_lock(&loop_devices_mutex); list_for_each_entry(l, &loop_devices, lo_list) if (disk_to_dev(l->lo_disk) == dev) { lo = l; break; } mutex_unlock(&loop_devices_mutex); return lo ? callback(lo, page) : -EIO; } #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; mutex_lock(&lo->lo_ctl_mutex); if (lo->lo_backing_file) p = d_path(&lo->lo_backing_file->f_path, buf, PAGE_SIZE - 1); mutex_unlock(&lo->lo_ctl_mutex); 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"); } LOOP_ATTR_RO(backing_file); LOOP_ATTR_RO(offset); LOOP_ATTR_RO(sizelimit); LOOP_ATTR_RO(autoclear); static struct attribute *loop_attrs[] = { &loop_attr_backing_file.attr, &loop_attr_offset.attr, &loop_attr_sizelimit.attr, &loop_attr_autoclear.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 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; if (!(file->f_mode & FMODE_WRITE)) lo_flags |= LO_FLAGS_READ_ONLY; error = -EINVAL; if (S_ISREG(inode->i_mode) || S_ISBLK(inode->i_mode)) { const struct address_space_operations *aops = mapping->a_ops; if (aops->write_begin) lo_flags |= LO_FLAGS_USE_AOPS; if (!(lo_flags & LO_FLAGS_USE_AOPS) && !file->f_op->write) lo_flags |= LO_FLAGS_READ_ONLY; lo_blocksize = S_ISBLK(inode->i_mode) ? inode->i_bdev->bd_block_size : PAGE_SIZE; error = 0; } else { goto out_putf; } size = get_loop_size(lo, file); if ((loff_t)(sector_t)size != size) { error = -EFBIG; goto out_putf; } if (!(mode & FMODE_WRITE)) lo_flags |= LO_FLAGS_READ_ONLY; 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 = transfer_none; 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)); bio_list_init(&lo->lo_bio_list); /* * set queue make_request_fn, and add limits based on lower level * device */ blk_queue_make_request(lo->lo_queue, loop_make_request); lo->lo_queue->queuedata = lo; lo->lo_queue->unplug_fn = loop_unplug; 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_thread = kthread_create(loop_thread, lo, "loop%d", lo->lo_number); if (IS_ERR(lo->lo_thread)) { error = PTR_ERR(lo->lo_thread); goto out_clr; } lo->lo_state = Lo_bound; wake_up_process(lo->lo_thread); if (max_part > 0) ioctl_by_bdev(bdev, BLKRRPART, 0); return 0; out_clr: loop_sysfs_exit(lo); lo->lo_thread = NULL; lo->lo_device = NULL; lo->lo_backing_file = NULL; lo->lo_flags = 0; set_capacity(lo->lo_disk, 0); invalidate_bdev(bdev); bd_set_size(bdev, 0); kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); mapping_set_gfp_mask(mapping, lo->old_gfp_mask); lo->lo_state = Lo_unbound; 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 block_device *bdev) { struct file *filp = lo->lo_backing_file; gfp_t gfp = lo->old_gfp_mask; if (lo->lo_state != Lo_bound) return -ENXIO; if (lo->lo_refcnt > 1) /* we needed one fd for the ioctl */ return -EBUSY; if (filp == NULL) return -EINVAL; spin_lock_irq(&lo->lo_lock); lo->lo_state = Lo_rundown; spin_unlock_irq(&lo->lo_lock); kthread_stop(lo->lo_thread); lo->lo_queue->unplug_fn = NULL; lo->lo_backing_file = NULL; 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; lo->lo_flags = 0; lo->lo_thread = NULL; 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) 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 (max_part > 0 && bdev) ioctl_by_bdev(bdev, BLKRRPART, 0); 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; uid_t uid = current_uid(); if (lo->lo_encrypt_key_size && 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) { lo->lo_offset = info->lo_offset; lo->lo_sizelimit = info->lo_sizelimit; if (figure_loop_size(lo)) return -EFBIG; } 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; } 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.mnt, file->f_path.dentry, &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) { int err; sector_t sec; loff_t sz; err = -ENXIO; if (unlikely(lo->lo_state != Lo_bound)) goto out; err = figure_loop_size(lo); if (unlikely(err)) goto out; sec = get_capacity(lo->lo_disk); /* the width of sector_t may be narrow for bit-shift */ sz = sec; sz <<= 9; mutex_lock(&bdev->bd_mutex); bd_set_size(bdev, sz); /* let user-space know about the new size */ kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); mutex_unlock(&bdev->bd_mutex); out: 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; 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, bdev); if (!err) goto out_unlocked; break; case LOOP_SET_STATUS: 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 = 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 = bdev->bd_disk->private_data; mutex_lock(&lo->lo_ctl_mutex); lo->lo_refcnt++; mutex_unlock(&lo->lo_ctl_mutex); return 0; } static int 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, NULL); if (!err) goto out_unlocked; } 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); out_unlocked: return 0; } 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, 0); MODULE_PARM_DESC(max_loop, "Maximum number of loop devices"); module_param(max_part, int, 0); 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; } int loop_unregister_transfer(int number) { unsigned int n = number; struct loop_device *lo; struct loop_func_table *xfer; if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL) return -EINVAL; xfer_funcs[n] = NULL; list_for_each_entry(lo, &loop_devices, lo_list) { mutex_lock(&lo->lo_ctl_mutex); if (lo->lo_encryption == xfer) loop_release_xfer(lo); mutex_unlock(&lo->lo_ctl_mutex); } return 0; } EXPORT_SYMBOL(loop_register_transfer); EXPORT_SYMBOL(loop_unregister_transfer); static struct loop_device *loop_alloc(int i) { struct loop_device *lo; struct gendisk *disk; lo = kzalloc(sizeof(*lo), GFP_KERNEL); if (!lo) goto out; lo->lo_queue = blk_alloc_queue(GFP_KERNEL); if (!lo->lo_queue) goto out_free_dev; disk = lo->lo_disk = alloc_disk(1 << part_shift); if (!disk) goto out_free_queue; mutex_init(&lo->lo_ctl_mutex); lo->lo_number = i; lo->lo_thread = NULL; init_waitqueue_head(&lo->lo_event); 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); return lo; out_free_queue: blk_cleanup_queue(lo->lo_queue); out_free_dev: kfree(lo); out: return NULL; } static void loop_free(struct loop_device *lo) { if (!lo->lo_queue->queue_lock) lo->lo_queue->queue_lock = &lo->lo_queue->__queue_lock; blk_cleanup_queue(lo->lo_queue); put_disk(lo->lo_disk); list_del(&lo->lo_list); kfree(lo); } static struct loop_device *loop_init_one(int i) { struct loop_device *lo; list_for_each_entry(lo, &loop_devices, lo_list) { if (lo->lo_number == i) return lo; } lo = loop_alloc(i); if (lo) { add_disk(lo->lo_disk); list_add_tail(&lo->lo_list, &loop_devices); } return lo; } static void loop_del_one(struct loop_device *lo) { del_gendisk(lo->lo_disk); loop_free(lo); } static struct kobject *loop_probe(dev_t dev, int *part, void *data) { struct loop_device *lo; struct kobject *kobj; mutex_lock(&loop_devices_mutex); lo = loop_init_one(dev & MINORMASK); kobj = lo ? get_disk(lo->lo_disk) : ERR_PTR(-ENOMEM); mutex_unlock(&loop_devices_mutex); *part = 0; return kobj; } static int __init loop_init(void) { int i, nr; unsigned long range; struct loop_device *lo, *next; /* * loop module now has a feature to instantiate underlying device * structure on-demand, provided that there is an access dev node. * However, this will not work well with user space tool that doesn't * know about such "feature". In order to not break any existing * tool, we do the following: * * (1) if max_loop is specified, create that many upfront, and this * also becomes a hard limit. * (2) if max_loop is not specified, create 8 loop device on module * load, user can further extend loop device by create dev node * themselves and have kernel automatically instantiate actual * device on-demand. */ part_shift = 0; if (max_part > 0) part_shift = fls(max_part); if (max_loop > 1UL << (MINORBITS - part_shift)) return -EINVAL; if (max_loop) { nr = max_loop; range = max_loop; } else { nr = 8; range = 1UL << (MINORBITS - part_shift); } if (register_blkdev(LOOP_MAJOR, "loop")) return -EIO; for (i = 0; i < nr; i++) { lo = loop_alloc(i); if (!lo) goto Enomem; list_add_tail(&lo->lo_list, &loop_devices); } /* point of no return */ list_for_each_entry(lo, &loop_devices, lo_list) add_disk(lo->lo_disk); blk_register_region(MKDEV(LOOP_MAJOR, 0), range, THIS_MODULE, loop_probe, NULL, NULL); printk(KERN_INFO "loop: module loaded\n"); return 0; Enomem: printk(KERN_INFO "loop: out of memory\n"); list_for_each_entry_safe(lo, next, &loop_devices, lo_list) loop_free(lo); unregister_blkdev(LOOP_MAJOR, "loop"); return -ENOMEM; } static void __exit loop_exit(void) { unsigned long range; struct loop_device *lo, *next; range = max_loop ? max_loop : 1UL << (MINORBITS - part_shift); list_for_each_entry_safe(lo, next, &loop_devices, lo_list) loop_del_one(lo); blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range); unregister_blkdev(LOOP_MAJOR, "loop"); } 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