diff options
Diffstat (limited to 'drivers/block/loop.c')
| -rw-r--r-- | drivers/block/loop.c | 1913 |
1 files changed, 1913 insertions, 0 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c new file mode 100644 index 00000000..bbca966f --- /dev/null +++ b/drivers/block/loop.c @@ -0,0 +1,1913 @@ +/* + * 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/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 <asm/uaccess.h> + +static DEFINE_IDR(loop_index_idr); +static DEFINE_MUTEX(loop_index_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) + raw_off; + char *loop_buf = kmap_atomic(loop_page) + loop_off; + + if (cmd == READ) + memcpy(loop_buf, raw_buf, size); + else + memcpy(raw_buf, loop_buf, size); + + kunmap_atomic(loop_buf); + kunmap_atomic(raw_buf); + 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) + 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, + .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_size(loff_t offset, loff_t sizelimit, struct file *file) +{ + loff_t size, loopsize; + + /* Compute loopsize in bytes */ + size = i_size_read(file->f_mapping->host); + loopsize = size - offset; + /* offset is beyond i_size, wierd but possible */ + if (loopsize < 0) + return 0; + + if (sizelimit > 0 && sizelimit < loopsize) + loopsize = sizelimit; + /* + * Unfortunately, if we want to do I/O on the device, + * the number of 512-byte sectors has to fit into a sector_t. + */ + return loopsize >> 9; +} + +static loff_t get_loop_size(struct loop_device *lo, struct file *file) +{ + return get_size(lo->lo_offset, lo->lo_sizelimit, file); +} + +static int +figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit) +{ + loff_t size = get_size(offset, sizelimit, lo->lo_backing_file); + sector_t x = (sector_t)size; + + 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); + 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_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 that does not need double + * buffering. + */ +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 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 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; + + 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; + } else { + do_lo_send = do_lo_send_direct_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 ssize_t +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; + ssize_t 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); + + return retval; +} + +static int +lo_receive(struct loop_device *lo, struct bio *bio, int bsize, loff_t pos) +{ + struct bio_vec *bvec; + ssize_t s; + int i; + + bio_for_each_segment(bvec, bio, i) { + s = do_lo_receive(lo, bvec, bsize, pos); + if (s < 0) + return s; + + if (s != bvec->bv_len) { + zero_fill_bio(bio); + break; + } + pos += bvec->bv_len; + } + return 0; +} + +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; + } + } + + /* + * We use punch hole to reclaim the free space used by the + * image a.k.a. discard. However we do not support discard if + * encryption is enabled, because it may give an attacker + * useful information. + */ + if (bio->bi_rw & REQ_DISCARD) { + struct file *file = lo->lo_backing_file; + int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE; + + if ((!file->f_op->fallocate) || + lo->lo_encrypt_key_size) { + ret = -EOPNOTSUPP; + goto out; + } + ret = file->f_op->fallocate(file, mode, pos, + bio->bi_size); + if (unlikely(ret && ret != -EINVAL && + ret != -EOPNOTSUPP)) + 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 void 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; + +out: + spin_unlock_irq(&lo->lo_lock); + bio_io_error(old_bio); +} + +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 (lo->lo_flags & LO_FLAGS_PARTSCAN) + ioctl_by_bdev(bdev, BLKRRPART, 0); + return 0; + + out_putf: + fput(file); + out: + return error; +} + +static inline int is_loop_device(struct file *file) +{ + struct inode *i = file->f_mapping->host; + + return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR; +} + +/* loop sysfs attributes */ + +static ssize_t loop_attr_show(struct device *dev, char *page, + ssize_t (*callback)(struct loop_device *, char *)) +{ + struct gendisk *disk = dev_to_disk(dev); + struct loop_device *lo = disk->private_data; + + return callback(lo, page); +} + +#define LOOP_ATTR_RO(_name) \ +static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \ +static ssize_t loop_attr_do_show_##_name(struct device *d, \ + struct device_attribute *attr, char *b) \ +{ \ + return loop_attr_show(d, b, loop_attr_##_name##_show); \ +} \ +static struct device_attribute loop_attr_##_name = \ + __ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL); + +static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf) +{ + ssize_t ret; + char *p = NULL; + + spin_lock_irq(&lo->lo_lock); + if (lo->lo_backing_file) + p = d_path(&lo->lo_backing_file->f_path, buf, PAGE_SIZE - 1); + spin_unlock_irq(&lo->lo_lock); + + if (IS_ERR_OR_NULL(p)) + ret = PTR_ERR(p); + else { + ret = strlen(p); + memmove(buf, p, ret); + buf[ret++] = '\n'; + buf[ret] = 0; + } + + return ret; +} + +static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf) +{ + return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset); +} + +static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf) +{ + return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit); +} + +static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf) +{ + int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR); + + return sprintf(buf, "%s\n", autoclear ? "1" : "0"); +} + +static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf) +{ + int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN); + + return sprintf(buf, "%s\n", partscan ? "1" : "0"); +} + +LOOP_ATTR_RO(backing_file); +LOOP_ATTR_RO(offset); +LOOP_ATTR_RO(sizelimit); +LOOP_ATTR_RO(autoclear); +LOOP_ATTR_RO(partscan); + +static struct attribute *loop_attrs[] = { + &loop_attr_backing_file.attr, + &loop_attr_offset.attr, + &loop_attr_sizelimit.attr, + &loop_attr_autoclear.attr, + &loop_attr_partscan.attr, + NULL, +}; + +static struct attribute_group loop_attribute_group = { + .name = "loop", + .attrs= loop_attrs, +}; + +static int loop_sysfs_init(struct loop_device *lo) +{ + return sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj, + &loop_attribute_group); +} + +static void loop_sysfs_exit(struct loop_device *lo) +{ + sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj, + &loop_attribute_group); +} + +static void loop_config_discard(struct loop_device *lo) +{ + struct file *file = lo->lo_backing_file; + struct inode *inode = file->f_mapping->host; + struct request_queue *q = lo->lo_queue; + + /* + * We use punch hole to reclaim the free space used by the + * image a.k.a. discard. However we do support discard if + * encryption is enabled, because it may give an attacker + * useful information. + */ + if ((!file->f_op->fallocate) || + lo->lo_encrypt_key_size) { + q->limits.discard_granularity = 0; + q->limits.discard_alignment = 0; + q->limits.max_discard_sectors = 0; + q->limits.discard_zeroes_data = 0; + queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q); + return; + } + + q->limits.discard_granularity = inode->i_sb->s_blocksize; + q->limits.discard_alignment = 0; + q->limits.max_discard_sectors = UINT_MAX >> 9; + q->limits.discard_zeroes_data = 1; + queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q); +} + +static int loop_set_fd(struct loop_device *lo, fmode_t mode, + struct block_device *bdev, unsigned int arg) +{ + struct file *file, *f; + struct inode *inode; + struct address_space *mapping; + unsigned lo_blocksize; + int lo_flags = 0; + int error; + loff_t size; + + /* This is safe, since we have a reference from open(). */ + __module_get(THIS_MODULE); + + error = -EBADF; + file = fget(arg); + if (!file) + goto out; + + error = -EBUSY; + if (lo->lo_state != Lo_unbound) + goto out_putf; + + /* Avoid recursion */ + f = file; + while (is_loop_device(f)) { + struct loop_device *l; + + if (f->f_mapping->host->i_bdev == bdev) + goto out_putf; + + l = f->f_mapping->host->i_bdev->bd_disk->private_data; + if (l->lo_state == Lo_unbound) { + error = -EINVAL; + goto out_putf; + } + f = l->lo_backing_file; + } + + mapping = file->f_mapping; + inode = mapping->host; + + error = -EINVAL; + if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode)) + goto out_putf; + + if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) || + !file->f_op->write) + lo_flags |= LO_FLAGS_READ_ONLY; + + lo_blocksize = S_ISBLK(inode->i_mode) ? + inode->i_bdev->bd_block_size : PAGE_SIZE; + + error = -EFBIG; + size = get_loop_size(lo, file); + if ((loff_t)(sector_t)size != size) + goto out_putf; + + error = 0; + + set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0); + + lo->lo_blocksize = lo_blocksize; + lo->lo_device = bdev; + lo->lo_flags = lo_flags; + lo->lo_backing_file = file; + lo->transfer = 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; + + 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 (part_shift) + lo->lo_flags |= LO_FLAGS_PARTSCAN; + if (lo->lo_flags & LO_FLAGS_PARTSCAN) + 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 file *filp = lo->lo_backing_file; + gfp_t gfp = lo->old_gfp_mask; + struct block_device *bdev = lo->lo_device; + + if (lo->lo_state != Lo_bound) + return -ENXIO; + + if (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); + + 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; + 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 (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev) + ioctl_by_bdev(bdev, BLKRRPART, 0); + lo->lo_flags = 0; + if (!part_shift) + lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN; + mutex_unlock(&lo->lo_ctl_mutex); + /* + * Need not hold lo_ctl_mutex to fput backing file. + * Calling fput holding lo_ctl_mutex triggers a circular + * lock dependency possibility warning as fput can take + * bd_mutex which is usually taken before lo_ctl_mutex. + */ + fput(filp); + return 0; +} + +static int +loop_set_status(struct loop_device *lo, const struct loop_info64 *info) +{ + int err; + struct loop_func_table *xfer; + 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) { + if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit)) + return -EFBIG; + } + loop_config_discard(lo); + + memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE); + memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE); + lo->lo_file_name[LO_NAME_SIZE-1] = 0; + lo->lo_crypt_name[LO_NAME_SIZE-1] = 0; + + if (!xfer) + xfer = &none_funcs; + lo->transfer = xfer->transfer; + lo->ioctl = xfer->ioctl; + + if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) != + (info->lo_flags & LO_FLAGS_AUTOCLEAR)) + lo->lo_flags ^= LO_FLAGS_AUTOCLEAR; + + if ((info->lo_flags & LO_FLAGS_PARTSCAN) && + !(lo->lo_flags & LO_FLAGS_PARTSCAN)) { + lo->lo_flags |= LO_FLAGS_PARTSCAN; + lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN; + ioctl_by_bdev(lo->lo_device, BLKRRPART, 0); + } + + lo->lo_encrypt_key_size = info->lo_encrypt_key_size; + lo->lo_init[0] = info->lo_init[0]; + lo->lo_init[1] = info->lo_init[1]; + if (info->lo_encrypt_key_size) { + memcpy(lo->lo_encrypt_key, info->lo_encrypt_key, + info->lo_encrypt_key_size); + lo->lo_key_owner = uid; + } + + return 0; +} + +static int +loop_get_status(struct loop_device *lo, struct loop_info64 *info) +{ + struct file *file = lo->lo_backing_file; + struct kstat stat; + int error; + + if (lo->lo_state != Lo_bound) + return -ENXIO; + error = vfs_getattr(file->f_path.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, lo->lo_offset, lo->lo_sizelimit); + 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); + if (!err) + goto out_unlocked; + break; + case LOOP_SET_STATUS: + err = -EPERM; + if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) + err = loop_set_status_old(lo, + (struct loop_info __user *)arg); + break; + case LOOP_GET_STATUS: + err = loop_get_status_old(lo, (struct loop_info __user *) arg); + break; + case LOOP_SET_STATUS64: + err = -EPERM; + if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) + err = loop_set_status64(lo, + (struct loop_info64 __user *) arg); + break; + case LOOP_GET_STATUS64: + err = loop_get_status64(lo, (struct loop_info64 __user *) arg); + break; + case LOOP_SET_CAPACITY: + err = -EPERM; + if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) + err = loop_set_capacity(lo, bdev); + break; + default: + err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL; + } + mutex_unlock(&lo->lo_ctl_mutex); + +out_unlocked: + return err; +} + +#ifdef CONFIG_COMPAT +struct compat_loop_info { + compat_int_t lo_number; /* ioctl r/o */ + compat_dev_t lo_device; /* ioctl r/o */ + compat_ulong_t lo_inode; /* ioctl r/o */ + compat_dev_t lo_rdevice; /* ioctl r/o */ + compat_int_t lo_offset; + compat_int_t lo_encrypt_type; + compat_int_t lo_encrypt_key_size; /* ioctl w/o */ + compat_int_t lo_flags; /* ioctl r/o */ + char lo_name[LO_NAME_SIZE]; + unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */ + compat_ulong_t lo_init[2]; + char reserved[4]; +}; + +/* + * Transfer 32-bit compatibility structure in userspace to 64-bit loop info + * - noinlined to reduce stack space usage in main part of driver + */ +static noinline int +loop_info64_from_compat(const struct compat_loop_info __user *arg, + struct loop_info64 *info64) +{ + struct compat_loop_info info; + + if (copy_from_user(&info, arg, sizeof(info))) + return -EFAULT; + + memset(info64, 0, sizeof(*info64)); + info64->lo_number = info.lo_number; + info64->lo_device = info.lo_device; + info64->lo_inode = info.lo_inode; + info64->lo_rdevice = info.lo_rdevice; + info64->lo_offset = info.lo_offset; + info64->lo_sizelimit = 0; + info64->lo_encrypt_type = info.lo_encrypt_type; + info64->lo_encrypt_key_size = info.lo_encrypt_key_size; + info64->lo_flags = info.lo_flags; + info64->lo_init[0] = info.lo_init[0]; + info64->lo_init[1] = info.lo_init[1]; + if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI) + memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE); + else + memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE); + memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE); + return 0; +} + +/* + * Transfer 64-bit loop info to 32-bit compatibility structure in userspace + * - noinlined to reduce stack space usage in main part of driver + */ +static noinline int +loop_info64_to_compat(const struct loop_info64 *info64, + struct compat_loop_info __user *arg) +{ + struct compat_loop_info info; + + memset(&info, 0, sizeof(info)); + info.lo_number = info64->lo_number; + info.lo_device = info64->lo_device; + info.lo_inode = info64->lo_inode; + info.lo_rdevice = info64->lo_rdevice; + info.lo_offset = info64->lo_offset; + info.lo_encrypt_type = info64->lo_encrypt_type; + info.lo_encrypt_key_size = info64->lo_encrypt_key_size; + info.lo_flags = info64->lo_flags; + info.lo_init[0] = info64->lo_init[0]; + info.lo_init[1] = info64->lo_init[1]; + if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI) + memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE); + else + memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE); + memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE); + + /* error in case values were truncated */ + if (info.lo_device != info64->lo_device || + info.lo_rdevice != info64->lo_rdevice || + info.lo_inode != info64->lo_inode || + info.lo_offset != info64->lo_offset || + info.lo_init[0] != info64->lo_init[0] || + info.lo_init[1] != info64->lo_init[1]) + return -EOVERFLOW; + + if (copy_to_user(arg, &info, sizeof(info))) + return -EFAULT; + return 0; +} + +static int +loop_set_status_compat(struct loop_device *lo, + const struct compat_loop_info __user *arg) +{ + struct loop_info64 info64; + int ret; + + ret = loop_info64_from_compat(arg, &info64); + if (ret < 0) + return ret; + return loop_set_status(lo, &info64); +} + +static int +loop_get_status_compat(struct loop_device *lo, + struct compat_loop_info __user *arg) +{ + struct loop_info64 info64; + int err = 0; + + if (!arg) + err = -EINVAL; + if (!err) + err = loop_get_status(lo, &info64); + if (!err) + err = loop_info64_to_compat(&info64, arg); + return err; +} + +static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode, + unsigned int cmd, unsigned long arg) +{ + struct loop_device *lo = bdev->bd_disk->private_data; + int err; + + switch(cmd) { + case LOOP_SET_STATUS: + mutex_lock(&lo->lo_ctl_mutex); + err = loop_set_status_compat( + lo, (const struct compat_loop_info __user *) arg); + mutex_unlock(&lo->lo_ctl_mutex); + break; + case LOOP_GET_STATUS: + mutex_lock(&lo->lo_ctl_mutex); + err = loop_get_status_compat( + lo, (struct compat_loop_info __user *) arg); + mutex_unlock(&lo->lo_ctl_mutex); + break; + case LOOP_SET_CAPACITY: + case LOOP_CLR_FD: + case LOOP_GET_STATUS64: + case LOOP_SET_STATUS64: + arg = (unsigned long) compat_ptr(arg); + case LOOP_SET_FD: + case LOOP_CHANGE_FD: + err = lo_ioctl(bdev, mode, cmd, arg); + break; + default: + err = -ENOIOCTLCMD; + break; + } + return err; +} +#endif + +static int lo_open(struct block_device *bdev, fmode_t mode) +{ + struct loop_device *lo; + int err = 0; + + mutex_lock(&loop_index_mutex); + lo = bdev->bd_disk->private_data; + if (!lo) { + err = -ENXIO; + goto out; + } + + mutex_lock(&lo->lo_ctl_mutex); + lo->lo_refcnt++; + mutex_unlock(&lo->lo_ctl_mutex); +out: + mutex_unlock(&loop_index_mutex); + return err; +} + +static 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); + 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, S_IRUGO); +MODULE_PARM_DESC(max_loop, "Maximum number of loop devices"); +module_param(max_part, int, S_IRUGO); +MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR); + +int loop_register_transfer(struct loop_func_table *funcs) +{ + unsigned int n = funcs->number; + + if (n >= MAX_LO_CRYPT || xfer_funcs[n]) + return -EINVAL; + xfer_funcs[n] = funcs; + return 0; +} + +static int unregister_transfer_cb(int id, void *ptr, void *data) +{ + struct loop_device *lo = ptr; + struct loop_func_table *xfer = data; + + mutex_lock(&lo->lo_ctl_mutex); + if (lo->lo_encryption == xfer) + loop_release_xfer(lo); + mutex_unlock(&lo->lo_ctl_mutex); + return 0; +} + +int loop_unregister_transfer(int number) +{ + unsigned int n = number; + struct loop_func_table *xfer; + + if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL) + return -EINVAL; + + xfer_funcs[n] = NULL; + idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer); + return 0; +} + +EXPORT_SYMBOL(loop_register_transfer); +EXPORT_SYMBOL(loop_unregister_transfer); + +static int loop_add(struct loop_device **l, int i) +{ + struct loop_device *lo; + struct gendisk *disk; + int err; + + lo = kzalloc(sizeof(*lo), GFP_KERNEL); + if (!lo) { + err = -ENOMEM; + goto out; + } + + err = idr_pre_get(&loop_index_idr, GFP_KERNEL); + if (err < 0) + goto out_free_dev; + + if (i >= 0) { + int m; + + /* create specific i in the index */ + err = idr_get_new_above(&loop_index_idr, lo, i, &m); + if (err >= 0 && i != m) { + idr_remove(&loop_index_idr, m); + err = -EEXIST; + } + } else if (i == -1) { + int m; + + /* get next free nr */ + err = idr_get_new(&loop_index_idr, lo, &m); + if (err >= 0) + i = m; + } else { + err = -EINVAL; + } + if (err < 0) + goto out_free_dev; + + 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; + + /* + * Disable partition scanning by default. The in-kernel partition + * scanning can be requested individually per-device during its + * setup. Userspace can always add and remove partitions from all + * devices. The needed partition minors are allocated from the + * extended minor space, the main loop device numbers will continue + * to match the loop minors, regardless of the number of partitions + * used. + * + * If max_part is given, partition scanning is globally enabled for + * all loop devices. The minors for the main loop devices will be + * multiples of max_part. + * + * Note: Global-for-all-devices, set-only-at-init, read-only module + * parameteters like 'max_loop' and 'max_part' make things needlessly + * complicated, are too static, inflexible and may surprise + * userspace tools. Parameters like this in general should be avoided. + */ + if (!part_shift) + disk->flags |= GENHD_FL_NO_PART_SCAN; + disk->flags |= GENHD_FL_EXT_DEVT; + mutex_init(&lo->lo_ctl_mutex); + lo->lo_number = i; + 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); + add_disk(disk); + *l = lo; + return lo->lo_number; + +out_free_queue: + blk_cleanup_queue(lo->lo_queue); +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); + put_disk(lo->lo_disk); + kfree(lo); +} + +static int find_free_cb(int id, void *ptr, void *data) +{ + struct loop_device *lo = ptr; + struct loop_device **l = data; + + if (lo->lo_state == Lo_unbound) { + *l = lo; + return 1; + } + return 0; +} + +static int loop_lookup(struct loop_device **l, int i) +{ + struct loop_device *lo; + int ret = -ENODEV; + + if (i < 0) { + int err; + + err = idr_for_each(&loop_index_idr, &find_free_cb, &lo); + if (err == 1) { + *l = lo; + ret = lo->lo_number; + } + goto out; + } + + /* lookup and return a specific i */ + lo = idr_find(&loop_index_idr, i); + if (lo) { + *l = lo; + ret = lo->lo_number; + } +out: + return ret; +} + +static struct kobject *loop_probe(dev_t dev, int *part, void *data) +{ + struct loop_device *lo; + struct kobject *kobj; + int err; + + mutex_lock(&loop_index_mutex); + err = loop_lookup(&lo, MINOR(dev) >> part_shift); + if (err < 0) + err = loop_add(&lo, MINOR(dev) >> part_shift); + if (err < 0) + kobj = ERR_PTR(err); + else + kobj = get_disk(lo->lo_disk); + mutex_unlock(&loop_index_mutex); + + *part = 0; + return kobj; +} + +static long loop_control_ioctl(struct file *file, unsigned int cmd, + unsigned long parm) +{ + struct loop_device *lo; + int ret = -ENOSYS; + + mutex_lock(&loop_index_mutex); + switch (cmd) { + case LOOP_CTL_ADD: + ret = loop_lookup(&lo, parm); + if (ret >= 0) { + ret = -EEXIST; + break; + } + ret = loop_add(&lo, parm); + break; + case LOOP_CTL_REMOVE: + ret = loop_lookup(&lo, parm); + if (ret < 0) + break; + mutex_lock(&lo->lo_ctl_mutex); + if (lo->lo_state != Lo_unbound) { + ret = -EBUSY; + mutex_unlock(&lo->lo_ctl_mutex); + break; + } + if (lo->lo_refcnt > 0) { + ret = -EBUSY; + mutex_unlock(&lo->lo_ctl_mutex); + break; + } + lo->lo_disk->private_data = NULL; + mutex_unlock(&lo->lo_ctl_mutex); + idr_remove(&loop_index_idr, lo->lo_number); + loop_remove(lo); + break; + case LOOP_CTL_GET_FREE: + ret = loop_lookup(&lo, -1); + if (ret >= 0) + break; + ret = loop_add(&lo, -1); + } + mutex_unlock(&loop_index_mutex); + + return ret; +} + +static const struct file_operations loop_ctl_fops = { + .open = nonseekable_open, + .unlocked_ioctl = loop_control_ioctl, + .compat_ioctl = loop_control_ioctl, + .owner = THIS_MODULE, + .llseek = noop_llseek, +}; + +static struct miscdevice loop_misc = { + .minor = LOOP_CTRL_MINOR, + .name = "loop-control", + .fops = &loop_ctl_fops, +}; + +MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR); +MODULE_ALIAS("devname:loop-control"); + +static int __init loop_init(void) +{ + int i, nr; + unsigned long range; + struct loop_device *lo; + int err; + + err = misc_register(&loop_misc); + if (err < 0) + return err; + + part_shift = 0; + if (max_part > 0) { + part_shift = fls(max_part); + + /* + * Adjust max_part according to part_shift as it is exported + * to user space so that user can decide correct minor number + * if [s]he want to create more devices. + * + * Note that -1 is required because partition 0 is reserved + * for the whole disk. + */ + max_part = (1UL << part_shift) - 1; + } + + if ((1UL << part_shift) > DISK_MAX_PARTS) + return -EINVAL; + + if (max_loop > 1UL << (MINORBITS - part_shift)) + return -EINVAL; + + /* + * If max_loop is specified, create that many devices upfront. + * This also becomes a hard limit. If max_loop is not specified, + * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module + * init time. Loop devices can be requested on-demand with the + * /dev/loop-control interface, or be instantiated by accessing + * a 'dead' device node. + */ + if (max_loop) { + nr = max_loop; + range = max_loop << part_shift; + } else { + nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT; + range = 1UL << MINORBITS; + } + + if (register_blkdev(LOOP_MAJOR, "loop")) + return -EIO; + + blk_register_region(MKDEV(LOOP_MAJOR, 0), range, + THIS_MODULE, loop_probe, NULL, NULL); + + /* pre-create number of devices given by config or max_loop */ + mutex_lock(&loop_index_mutex); + for (i = 0; i < nr; i++) + loop_add(&lo, i); + mutex_unlock(&loop_index_mutex); + + printk(KERN_INFO "loop: module loaded\n"); + return 0; +} + +static int loop_exit_cb(int id, void *ptr, void *data) +{ + struct loop_device *lo = ptr; + + loop_remove(lo); + return 0; +} + +static void __exit loop_exit(void) +{ + unsigned long range; + + range = max_loop ? max_loop << part_shift : 1UL << MINORBITS; + + idr_for_each(&loop_index_idr, &loop_exit_cb, NULL); + idr_remove_all(&loop_index_idr); + idr_destroy(&loop_index_idr); + + blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range); + unregister_blkdev(LOOP_MAJOR, "loop"); + + misc_deregister(&loop_misc); +} + +module_init(loop_init); +module_exit(loop_exit); + +#ifndef MODULE +static int __init max_loop_setup(char *str) +{ + max_loop = simple_strtol(str, NULL, 0); + return 1; +} + +__setup("max_loop=", max_loop_setup); +#endif |