diff options
Diffstat (limited to 'drivers/block/loop.c')
| -rw-r--r-- | drivers/block/loop.c | 1348 |
1 files changed, 1348 insertions, 0 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c new file mode 100644 index 00000000000..6f011d0d8e9 --- /dev/null +++ b/drivers/block/loop.c @@ -0,0 +1,1348 @@ +/* + * 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. Bolsų, <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 prepare_write and/or commit_write are 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/config.h> +#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/devfs_fs_kernel.h> +#include <linux/smp_lock.h> +#include <linux/swap.h> +#include <linux/slab.h> +#include <linux/loop.h> +#include <linux/suspend.h> +#include <linux/writeback.h> +#include <linux/buffer_head.h> /* for invalidate_bdev() */ +#include <linux/completion.h> +#include <linux/highmem.h> +#include <linux/gfp.h> + +#include <asm/uaccess.h> + +static int max_loop = 8; +static struct loop_device *loop_dev; +static struct gendisk **disks; + +/* + * 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(raw_buf, KM_USER0); + kunmap_atomic(loop_buf, KM_USER1); + 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(raw_buf, KM_USER0); + kunmap_atomic(loop_buf, KM_USER1); + 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(disks[lo->lo_number], 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 prepare_write and commit_write. + */ +static int do_lo_send_aops(struct loop_device *lo, struct bio_vec *bvec, + int bsize, loff_t pos, struct page *page) +{ + struct file *file = lo->lo_backing_file; /* kudos to NFsckingS */ + struct address_space *mapping = file->f_mapping; + struct address_space_operations *aops = mapping->a_ops; + pgoff_t index; + unsigned offset, bv_offs; + int len, ret = 0; + + down(&mapping->host->i_sem); + 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; + int transfer_result; + + IV = ((sector_t)index << (PAGE_CACHE_SHIFT - 9))+(offset >> 9); + size = PAGE_CACHE_SIZE - offset; + if (size > len) + size = len; + page = grab_cache_page(mapping, index); + if (unlikely(!page)) + goto fail; + if (unlikely(aops->prepare_write(file, page, offset, + offset + size))) + goto unlock; + transfer_result = lo_do_transfer(lo, WRITE, page, offset, + bvec->bv_page, bv_offs, size, IV); + if (unlikely(transfer_result)) { + char *kaddr; + + /* + * The transfer failed, but we still write the data to + * keep prepare/commit calls balanced. + */ + printk(KERN_ERR "loop: transfer error block %llu\n", + (unsigned long long)index); + kaddr = kmap_atomic(page, KM_USER0); + memset(kaddr + offset, 0, size); + kunmap_atomic(kaddr, KM_USER0); + } + flush_dcache_page(page); + if (unlikely(aops->commit_write(file, page, offset, + offset + size))) + goto unlock; + if (unlikely(transfer_result)) + goto unlock; + bv_offs += size; + len -= size; + offset = 0; + index++; + pos += size; + unlock_page(page); + page_cache_release(page); + } +out: + up(&mapping->host->i_sem); + return ret; +unlock: + unlock_page(page); + page_cache_release(page); +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 inline int __do_lo_send_write(struct file *file, + u8 __user *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 prepare_write and commit_write. + * 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, int bsize, loff_t pos, struct page *page) +{ + ssize_t bw = __do_lo_send_write(lo->lo_backing_file, + (u8 __user *)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 prepare_write and commit_write. 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, + int bsize, 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, + (u8 __user *)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, int bsize, + loff_t pos) +{ + int (*do_lo_send)(struct loop_device *, struct bio_vec *, int, 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, bsize, 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_read_actor(read_descriptor_t *desc, struct page *page, + unsigned long offset, unsigned long size) +{ + unsigned long count = desc->count; + struct lo_read_data *p = desc->arg.data; + struct loop_device *lo = p->lo; + sector_t IV; + + IV = ((sector_t) page->index << (PAGE_CACHE_SHIFT - 9))+(offset >> 9); + + if (size > count) + size = count; + + if (lo_do_transfer(lo, READ, page, offset, p->page, p->offset, size, IV)) { + size = 0; + printk(KERN_ERR "loop: transfer error block %ld\n", + page->index); + desc->error = -EINVAL; + } + + flush_dcache_page(p->page); + + desc->count = count - size; + desc->written += size; + p->offset += size; + return size; +} + +static int +do_lo_receive(struct loop_device *lo, + struct bio_vec *bvec, int bsize, loff_t pos) +{ + struct lo_read_data cookie; + struct file *file; + int retval; + + cookie.lo = lo; + cookie.page = bvec->bv_page; + cookie.offset = bvec->bv_offset; + cookie.bsize = bsize; + file = lo->lo_backing_file; + retval = file->f_op->sendfile(file, &pos, bvec->bv_len, + lo_read_actor, &cookie); + return (retval < 0)? retval: 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) + ret = lo_send(lo, bio, lo->lo_blocksize, pos); + else + ret = lo_receive(lo, bio, lo->lo_blocksize, pos); + return ret; +} + +/* + * Add bio to back of pending list + */ +static void loop_add_bio(struct loop_device *lo, struct bio *bio) +{ + unsigned long flags; + + spin_lock_irqsave(&lo->lo_lock, flags); + if (lo->lo_biotail) { + lo->lo_biotail->bi_next = bio; + lo->lo_biotail = bio; + } else + lo->lo_bio = lo->lo_biotail = bio; + spin_unlock_irqrestore(&lo->lo_lock, flags); + + up(&lo->lo_bh_mutex); +} + +/* + * Grab first pending buffer + */ +static struct bio *loop_get_bio(struct loop_device *lo) +{ + struct bio *bio; + + spin_lock_irq(&lo->lo_lock); + if ((bio = lo->lo_bio)) { + if (bio == lo->lo_biotail) + lo->lo_biotail = NULL; + lo->lo_bio = bio->bi_next; + bio->bi_next = NULL; + } + spin_unlock_irq(&lo->lo_lock); + + return bio; +} + +static int loop_make_request(request_queue_t *q, struct bio *old_bio) +{ + struct loop_device *lo = q->queuedata; + int rw = bio_rw(old_bio); + + if (!lo) + goto out; + + spin_lock_irq(&lo->lo_lock); + if (lo->lo_state != Lo_bound) + goto inactive; + atomic_inc(&lo->lo_pending); + spin_unlock_irq(&lo->lo_lock); + + if (rw == WRITE) { + if (lo->lo_flags & LO_FLAGS_READ_ONLY) + goto err; + } else if (rw == READA) { + rw = READ; + } else if (rw != READ) { + printk(KERN_ERR "loop: unknown command (%x)\n", rw); + goto err; + } + loop_add_bio(lo, old_bio); + return 0; +err: + if (atomic_dec_and_test(&lo->lo_pending)) + up(&lo->lo_bh_mutex); +out: + bio_io_error(old_bio, old_bio->bi_size); + return 0; +inactive: + spin_unlock_irq(&lo->lo_lock); + goto out; +} + +/* + * kick off io on the underlying address space + */ +static void loop_unplug(request_queue_t *q) +{ + struct loop_device *lo = q->queuedata; + + clear_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags); + 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) +{ + int ret; + + if (unlikely(!bio->bi_bdev)) { + do_loop_switch(lo, bio->bi_private); + bio_put(bio); + } else { + ret = do_bio_filebacked(lo, bio); + bio_endio(bio, bio->bi_size, 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. + */ +static int loop_thread(void *data) +{ + struct loop_device *lo = data; + struct bio *bio; + + daemonize("loop%d", lo->lo_number); + + /* + * loop can be used in an encrypted device, + * hence, it mustn't be stopped at all + * because it could be indirectly used during suspension + */ + current->flags |= PF_NOFREEZE; + + set_user_nice(current, -20); + + lo->lo_state = Lo_bound; + atomic_inc(&lo->lo_pending); + + /* + * up sem, we are running + */ + up(&lo->lo_sem); + + for (;;) { + down_interruptible(&lo->lo_bh_mutex); + /* + * could be upped because of tear-down, not because of + * pending work + */ + if (!atomic_read(&lo->lo_pending)) + break; + + bio = loop_get_bio(lo); + if (!bio) { + printk("loop: missing bio\n"); + continue; + } + loop_handle_bio(lo, bio); + + /* + * upped both for pending work and tear-down, lo_pending + * will hit zero then + */ + if (atomic_dec_and_test(&lo->lo_pending)) + break; + } + + up(&lo->lo_sem); + 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, 1); + 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; +} + +/* + * 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 = file->f_mapping; + + mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask); + lo->lo_backing_file = file; + lo->lo_blocksize = mapping->host->i_blksize; + lo->old_gfp_mask = mapping_gfp_mask(mapping); + mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); + 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 file *lo_file, + 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; + + /* new backing store needs to support loop (eg sendfile) */ + if (!inode->i_fop->sendfile) + 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); + 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; +} + +static int loop_set_fd(struct loop_device *lo, struct file *lo_file, + 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_rdev == lo_file->f_mapping->host->i_rdev) + 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)) { + struct address_space_operations *aops = mapping->a_ops; + /* + * If we can't read - sorry. If we only can't write - well, + * it's going to be read-only. + */ + if (!file->f_op->sendfile) + goto out_putf; + if (aops->prepare_write && aops->commit_write) + 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 = inode->i_blksize; + 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 (!(lo_file->f_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 = 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)); + + lo->lo_bio = lo->lo_biotail = NULL; + + /* + * 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; + + set_capacity(disks[lo->lo_number], size); + bd_set_size(bdev, size << 9); + + set_blocksize(bdev, lo_blocksize); + + kernel_thread(loop_thread, lo, CLONE_KERNEL); + down(&lo->lo_sem); + return 0; + + out_putf: + fput(file); + out: + /* This is safe: open() is still holding a reference. */ + module_put(THIS_MODULE); + return error; +} + +static int +loop_release_xfer(struct loop_device *lo) +{ + int err = 0; + struct loop_func_table *xfer = lo->lo_encryption; + + if (xfer) { + if (xfer->release) + err = xfer->release(lo); + lo->transfer = NULL; + lo->lo_encryption = NULL; + module_put(xfer->owner); + } + return err; +} + +static int +loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer, + const struct loop_info64 *i) +{ + int err = 0; + + if (xfer) { + struct module *owner = xfer->owner; + + if (!try_module_get(owner)) + return -EINVAL; + if (xfer->init) + err = xfer->init(lo, i); + if (err) + module_put(owner); + else + lo->lo_encryption = xfer; + } + return err; +} + +static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev) +{ + struct file *filp = lo->lo_backing_file; + int 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; + if (atomic_dec_and_test(&lo->lo_pending)) + up(&lo->lo_bh_mutex); + spin_unlock_irq(&lo->lo_lock); + + down(&lo->lo_sem); + + 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; + 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); + invalidate_bdev(bdev, 0); + set_capacity(disks[lo->lo_number], 0); + bd_set_size(bdev, 0); + mapping_set_gfp_mask(filp->f_mapping, gfp); + lo->lo_state = Lo_unbound; + fput(filp); + /* This is safe: open() is still holding a reference. */ + module_put(THIS_MODULE); + return 0; +} + +static int +loop_set_status(struct loop_device *lo, const struct loop_info64 *info) +{ + int err; + struct loop_func_table *xfer; + + if (lo->lo_encrypt_key_size && lo->lo_key_owner != current->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; + + 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 = current->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_vfsmnt, file->f_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 lo_ioctl(struct inode * inode, struct file * file, + unsigned int cmd, unsigned long arg) +{ + struct loop_device *lo = inode->i_bdev->bd_disk->private_data; + int err; + + down(&lo->lo_ctl_mutex); + switch (cmd) { + case LOOP_SET_FD: + err = loop_set_fd(lo, file, inode->i_bdev, arg); + break; + case LOOP_CHANGE_FD: + err = loop_change_fd(lo, file, inode->i_bdev, arg); + break; + case LOOP_CLR_FD: + err = loop_clr_fd(lo, inode->i_bdev); + 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; + default: + err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL; + } + up(&lo->lo_ctl_mutex); + return err; +} + +static int lo_open(struct inode *inode, struct file *file) +{ + struct loop_device *lo = inode->i_bdev->bd_disk->private_data; + + down(&lo->lo_ctl_mutex); + lo->lo_refcnt++; + up(&lo->lo_ctl_mutex); + + return 0; +} + +static int lo_release(struct inode *inode, struct file *file) +{ + struct loop_device *lo = inode->i_bdev->bd_disk->private_data; + + down(&lo->lo_ctl_mutex); + --lo->lo_refcnt; + up(&lo->lo_ctl_mutex); + + return 0; +} + +static struct block_device_operations lo_fops = { + .owner = THIS_MODULE, + .open = lo_open, + .release = lo_release, + .ioctl = lo_ioctl, +}; + +/* + * And now the modules code and kernel interface. + */ +module_param(max_loop, int, 0); +MODULE_PARM_DESC(max_loop, "Maximum number of loop devices (1-256)"); +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; + + for (lo = &loop_dev[0]; lo < &loop_dev[max_loop]; lo++) { + down(&lo->lo_ctl_mutex); + + if (lo->lo_encryption == xfer) + loop_release_xfer(lo); + + up(&lo->lo_ctl_mutex); + } + + return 0; +} + +EXPORT_SYMBOL(loop_register_transfer); +EXPORT_SYMBOL(loop_unregister_transfer); + +static int __init loop_init(void) +{ + int i; + + if (max_loop < 1 || max_loop > 256) { + printk(KERN_WARNING "loop: invalid max_loop (must be between" + " 1 and 256), using default (8)\n"); + max_loop = 8; + } + + if (register_blkdev(LOOP_MAJOR, "loop")) + return -EIO; + + loop_dev = kmalloc(max_loop * sizeof(struct loop_device), GFP_KERNEL); + if (!loop_dev) + goto out_mem1; + memset(loop_dev, 0, max_loop * sizeof(struct loop_device)); + + disks = kmalloc(max_loop * sizeof(struct gendisk *), GFP_KERNEL); + if (!disks) + goto out_mem2; + + for (i = 0; i < max_loop; i++) { + disks[i] = alloc_disk(1); + if (!disks[i]) + goto out_mem3; + } + + devfs_mk_dir("loop"); + + for (i = 0; i < max_loop; i++) { + struct loop_device *lo = &loop_dev[i]; + struct gendisk *disk = disks[i]; + + memset(lo, 0, sizeof(*lo)); + lo->lo_queue = blk_alloc_queue(GFP_KERNEL); + if (!lo->lo_queue) + goto out_mem4; + init_MUTEX(&lo->lo_ctl_mutex); + init_MUTEX_LOCKED(&lo->lo_sem); + init_MUTEX_LOCKED(&lo->lo_bh_mutex); + lo->lo_number = i; + spin_lock_init(&lo->lo_lock); + disk->major = LOOP_MAJOR; + disk->first_minor = i; + disk->fops = &lo_fops; + sprintf(disk->disk_name, "loop%d", i); + sprintf(disk->devfs_name, "loop/%d", i); + disk->private_data = lo; + disk->queue = lo->lo_queue; + } + + /* We cannot fail after we call this, so another loop!*/ + for (i = 0; i < max_loop; i++) + add_disk(disks[i]); + printk(KERN_INFO "loop: loaded (max %d devices)\n", max_loop); + return 0; + +out_mem4: + while (i--) + blk_put_queue(loop_dev[i].lo_queue); + devfs_remove("loop"); + i = max_loop; +out_mem3: + while (i--) + put_disk(disks[i]); + kfree(disks); +out_mem2: + kfree(loop_dev); +out_mem1: + unregister_blkdev(LOOP_MAJOR, "loop"); + printk(KERN_ERR "loop: ran out of memory\n"); + return -ENOMEM; +} + +static void loop_exit(void) +{ + int i; + + for (i = 0; i < max_loop; i++) { + del_gendisk(disks[i]); + blk_put_queue(loop_dev[i].lo_queue); + put_disk(disks[i]); + } + devfs_remove("loop"); + if (unregister_blkdev(LOOP_MAJOR, "loop")) + printk(KERN_WARNING "loop: cannot unregister blkdev\n"); + + kfree(disks); + kfree(loop_dev); +} + +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 |