| /* |
| * linux/drivers/block/loop.c |
| * |
| * Written by Theodore Ts'o, 3/29/93 |
| * |
| * Copyright 1993 by Theodore Ts'o. Redistribution of this file is |
| * permitted under the GNU General Public License. |
| * |
| * DES encryption plus some minor changes by Werner Almesberger, 30-MAY-1993 |
| * more DES encryption plus IDEA encryption by Nicholas J. Leon, June 20, 1996 |
| * |
| * Modularized and updated for 1.1.16 kernel - Mitch Dsouza 28th May 1994 |
| * Adapted for 1.3.59 kernel - Andries Brouwer, 1 Feb 1996 |
| * |
| * Fixed do_loop_request() re-entrancy - Vincent.Renardias@waw.com Mar 20, 1997 |
| * |
| * Added devfs support - Richard Gooch <rgooch@atnf.csiro.au> 16-Jan-1998 |
| * |
| * Handle sparse backing files correctly - Kenn Humborg, Jun 28, 1998 |
| * |
| * Loadable modules and other fixes by AK, 1998 |
| * |
| * Make real block number available to downstream transfer functions, enables |
| * CBC (and relatives) mode encryption requiring unique IVs per data block. |
| * Reed H. Petty, rhp@draper.net |
| * |
| * Maximum number of loop devices now dynamic via max_loop module parameter. |
| * Russell Kroll <rkroll@exploits.org> 19990701 |
| * |
| * Maximum number of loop devices when compiled-in now selectable by passing |
| * max_loop=<1-255> to the kernel on boot. |
| * Erik I. Bolsø, <eriki@himolde.no>, Oct 31, 1999 |
| * |
| * Completely rewrite request handling to be make_request_fn style and |
| * non blocking, pushing work to a helper thread. Lots of fixes from |
| * Al Viro too. |
| * Jens Axboe <axboe@suse.de>, Nov 2000 |
| * |
| * Support up to 256 loop devices |
| * Heinz Mauelshagen <mge@sistina.com>, Feb 2002 |
| * |
| * Support for falling back on the write file operation when the address space |
| * operations write_begin is not available on the backing filesystem. |
| * Anton Altaparmakov, 16 Feb 2005 |
| * |
| * Still To Fix: |
| * - Advisory locking is ignored here. |
| * - Should use an own CAP_* category instead of CAP_SYS_ADMIN |
| * |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/moduleparam.h> |
| #include <linux/sched.h> |
| #include <linux/fs.h> |
| #include <linux/file.h> |
| #include <linux/stat.h> |
| #include <linux/errno.h> |
| #include <linux/major.h> |
| #include <linux/wait.h> |
| #include <linux/blkdev.h> |
| #include <linux/blkpg.h> |
| #include <linux/init.h> |
| #include <linux/swap.h> |
| #include <linux/slab.h> |
| #include <linux/compat.h> |
| #include <linux/suspend.h> |
| #include <linux/freezer.h> |
| #include <linux/mutex.h> |
| #include <linux/writeback.h> |
| #include <linux/completion.h> |
| #include <linux/highmem.h> |
| #include <linux/kthread.h> |
| #include <linux/splice.h> |
| #include <linux/sysfs.h> |
| #include <linux/miscdevice.h> |
| #include <linux/falloc.h> |
| #include <linux/uio.h> |
| #include "loop.h" |
| |
| #include <asm/uaccess.h> |
| |
| static DEFINE_IDR(loop_index_idr); |
| static DEFINE_MUTEX(loop_index_mutex); |
| |
| static int max_part; |
| static int part_shift; |
| |
| static int transfer_xor(struct loop_device *lo, int cmd, |
| struct page *raw_page, unsigned raw_off, |
| struct page *loop_page, unsigned loop_off, |
| int size, sector_t real_block) |
| { |
| char *raw_buf = kmap_atomic(raw_page) + raw_off; |
| char *loop_buf = kmap_atomic(loop_page) + loop_off; |
| char *in, *out, *key; |
| int i, keysize; |
| |
| if (cmd == READ) { |
| in = raw_buf; |
| out = loop_buf; |
| } else { |
| in = loop_buf; |
| out = raw_buf; |
| } |
| |
| key = lo->lo_encrypt_key; |
| keysize = lo->lo_encrypt_key_size; |
| for (i = 0; i < size; i++) |
| *out++ = *in++ ^ key[(i & 511) % keysize]; |
| |
| kunmap_atomic(loop_buf); |
| kunmap_atomic(raw_buf); |
| cond_resched(); |
| return 0; |
| } |
| |
| static int xor_init(struct loop_device *lo, const struct loop_info64 *info) |
| { |
| if (unlikely(info->lo_encrypt_key_size <= 0)) |
| return -EINVAL; |
| return 0; |
| } |
| |
| static struct loop_func_table none_funcs = { |
| .number = LO_CRYPT_NONE, |
| }; |
| |
| static struct loop_func_table xor_funcs = { |
| .number = LO_CRYPT_XOR, |
| .transfer = transfer_xor, |
| .init = xor_init |
| }; |
| |
| /* xfer_funcs[0] is special - its release function is never called */ |
| static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = { |
| &none_funcs, |
| &xor_funcs |
| }; |
| |
| static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file) |
| { |
| loff_t loopsize; |
| |
| /* Compute loopsize in bytes */ |
| loopsize = i_size_read(file->f_mapping->host); |
| if (offset > 0) |
| loopsize -= offset; |
| /* offset is beyond i_size, weird but possible */ |
| if (loopsize < 0) |
| return 0; |
| |
| if (sizelimit > 0 && sizelimit < loopsize) |
| loopsize = sizelimit; |
| /* |
| * Unfortunately, if we want to do I/O on the device, |
| * the number of 512-byte sectors has to fit into a sector_t. |
| */ |
| return loopsize >> 9; |
| } |
| |
| static loff_t get_loop_size(struct loop_device *lo, struct file *file) |
| { |
| return get_size(lo->lo_offset, lo->lo_sizelimit, file); |
| } |
| |
| static void __loop_update_dio(struct loop_device *lo, bool dio) |
| { |
| struct file *file = lo->lo_backing_file; |
| struct address_space *mapping = file->f_mapping; |
| struct inode *inode = mapping->host; |
| unsigned short sb_bsize = 0; |
| unsigned dio_align = 0; |
| bool use_dio; |
| |
| if (inode->i_sb->s_bdev) { |
| sb_bsize = bdev_logical_block_size(inode->i_sb->s_bdev); |
| dio_align = sb_bsize - 1; |
| } |
| |
| /* |
| * We support direct I/O only if lo_offset is aligned with the |
| * logical I/O size of backing device, and the logical block |
| * size of loop is bigger than the backing device's and the loop |
| * needn't transform transfer. |
| * |
| * TODO: the above condition may be loosed in the future, and |
| * direct I/O may be switched runtime at that time because most |
| * of requests in sane appplications should be PAGE_SIZE algined |
| */ |
| if (dio) { |
| if (queue_logical_block_size(lo->lo_queue) >= sb_bsize && |
| !(lo->lo_offset & dio_align) && |
| mapping->a_ops->direct_IO && |
| !lo->transfer) |
| use_dio = true; |
| else |
| use_dio = false; |
| } else { |
| use_dio = false; |
| } |
| |
| if (lo->use_dio == use_dio) |
| return; |
| |
| /* flush dirty pages before changing direct IO */ |
| vfs_fsync(file, 0); |
| |
| /* |
| * The flag of LO_FLAGS_DIRECT_IO is handled similarly with |
| * LO_FLAGS_READ_ONLY, both are set from kernel, and losetup |
| * will get updated by ioctl(LOOP_GET_STATUS) |
| */ |
| blk_mq_freeze_queue(lo->lo_queue); |
| lo->use_dio = use_dio; |
| if (use_dio) |
| lo->lo_flags |= LO_FLAGS_DIRECT_IO; |
| else |
| lo->lo_flags &= ~LO_FLAGS_DIRECT_IO; |
| blk_mq_unfreeze_queue(lo->lo_queue); |
| } |
| |
| static int |
| figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit) |
| { |
| loff_t size = get_size(offset, sizelimit, lo->lo_backing_file); |
| sector_t x = (sector_t)size; |
| struct block_device *bdev = lo->lo_device; |
| |
| if (unlikely((loff_t)x != size)) |
| return -EFBIG; |
| if (lo->lo_offset != offset) |
| lo->lo_offset = offset; |
| if (lo->lo_sizelimit != sizelimit) |
| lo->lo_sizelimit = sizelimit; |
| set_capacity(lo->lo_disk, x); |
| bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9); |
| /* let user-space know about the new size */ |
| kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); |
| return 0; |
| } |
| |
| static inline int |
| lo_do_transfer(struct loop_device *lo, int cmd, |
| struct page *rpage, unsigned roffs, |
| struct page *lpage, unsigned loffs, |
| int size, sector_t rblock) |
| { |
| int ret; |
| |
| ret = lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock); |
| if (likely(!ret)) |
| return 0; |
| |
| printk_ratelimited(KERN_ERR |
| "loop: Transfer error at byte offset %llu, length %i.\n", |
| (unsigned long long)rblock << 9, size); |
| return ret; |
| } |
| |
| static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos) |
| { |
| struct iov_iter i; |
| ssize_t bw; |
| |
| iov_iter_bvec(&i, ITER_BVEC | WRITE, bvec, 1, bvec->bv_len); |
| |
| file_start_write(file); |
| bw = vfs_iter_write(file, &i, ppos); |
| file_end_write(file); |
| |
| if (likely(bw == bvec->bv_len)) |
| return 0; |
| |
| printk_ratelimited(KERN_ERR |
| "loop: Write error at byte offset %llu, length %i.\n", |
| (unsigned long long)*ppos, bvec->bv_len); |
| if (bw >= 0) |
| bw = -EIO; |
| return bw; |
| } |
| |
| static int lo_write_simple(struct loop_device *lo, struct request *rq, |
| loff_t pos) |
| { |
| struct bio_vec bvec; |
| struct req_iterator iter; |
| int ret = 0; |
| |
| rq_for_each_segment(bvec, rq, iter) { |
| ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos); |
| if (ret < 0) |
| break; |
| cond_resched(); |
| } |
| |
| return ret; |
| } |
| |
| /* |
| * This is the slow, transforming version that needs to double buffer the |
| * data as it cannot do the transformations in place without having direct |
| * access to the destination pages of the backing file. |
| */ |
| static int lo_write_transfer(struct loop_device *lo, struct request *rq, |
| loff_t pos) |
| { |
| struct bio_vec bvec, b; |
| struct req_iterator iter; |
| struct page *page; |
| int ret = 0; |
| |
| page = alloc_page(GFP_NOIO); |
| if (unlikely(!page)) |
| return -ENOMEM; |
| |
| rq_for_each_segment(bvec, rq, iter) { |
| ret = lo_do_transfer(lo, WRITE, page, 0, bvec.bv_page, |
| bvec.bv_offset, bvec.bv_len, pos >> 9); |
| if (unlikely(ret)) |
| break; |
| |
| b.bv_page = page; |
| b.bv_offset = 0; |
| b.bv_len = bvec.bv_len; |
| ret = lo_write_bvec(lo->lo_backing_file, &b, &pos); |
| if (ret < 0) |
| break; |
| } |
| |
| __free_page(page); |
| return ret; |
| } |
| |
| static int lo_read_simple(struct loop_device *lo, struct request *rq, |
| loff_t pos) |
| { |
| struct bio_vec bvec; |
| struct req_iterator iter; |
| struct iov_iter i; |
| ssize_t len; |
| |
| rq_for_each_segment(bvec, rq, iter) { |
| iov_iter_bvec(&i, ITER_BVEC, &bvec, 1, bvec.bv_len); |
| len = vfs_iter_read(lo->lo_backing_file, &i, &pos); |
| if (len < 0) |
| return len; |
| |
| flush_dcache_page(bvec.bv_page); |
| |
| if (len != bvec.bv_len) { |
| struct bio *bio; |
| |
| __rq_for_each_bio(bio, rq) |
| zero_fill_bio(bio); |
| break; |
| } |
| cond_resched(); |
| } |
| |
| return 0; |
| } |
| |
| static int lo_read_transfer(struct loop_device *lo, struct request *rq, |
| loff_t pos) |
| { |
| struct bio_vec bvec, b; |
| struct req_iterator iter; |
| struct iov_iter i; |
| struct page *page; |
| ssize_t len; |
| int ret = 0; |
| |
| page = alloc_page(GFP_NOIO); |
| if (unlikely(!page)) |
| return -ENOMEM; |
| |
| rq_for_each_segment(bvec, rq, iter) { |
| loff_t offset = pos; |
| |
| b.bv_page = page; |
| b.bv_offset = 0; |
| b.bv_len = bvec.bv_len; |
| |
| iov_iter_bvec(&i, ITER_BVEC, &b, 1, b.bv_len); |
| len = vfs_iter_read(lo->lo_backing_file, &i, &pos); |
| if (len < 0) { |
| ret = len; |
| goto out_free_page; |
| } |
| |
| ret = lo_do_transfer(lo, READ, page, 0, bvec.bv_page, |
| bvec.bv_offset, len, offset >> 9); |
| if (ret) |
| goto out_free_page; |
| |
| flush_dcache_page(bvec.bv_page); |
| |
| if (len != bvec.bv_len) { |
| struct bio *bio; |
| |
| __rq_for_each_bio(bio, rq) |
| zero_fill_bio(bio); |
| break; |
| } |
| } |
| |
| ret = 0; |
| out_free_page: |
| __free_page(page); |
| return ret; |
| } |
| |
| static int lo_discard(struct loop_device *lo, struct request *rq, loff_t pos) |
| { |
| /* |
| * We use punch hole to reclaim the free space used by the |
| * image a.k.a. discard. However we do not support discard if |
| * encryption is enabled, because it may give an attacker |
| * useful information. |
| */ |
| struct file *file = lo->lo_backing_file; |
| int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE; |
| int ret; |
| |
| if ((!file->f_op->fallocate) || lo->lo_encrypt_key_size) { |
| ret = -EOPNOTSUPP; |
| goto out; |
| } |
| |
| ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq)); |
| if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP)) |
| ret = -EIO; |
| out: |
| return ret; |
| } |
| |
| static int lo_req_flush(struct loop_device *lo, struct request *rq) |
| { |
| struct file *file = lo->lo_backing_file; |
| int ret = vfs_fsync(file, 0); |
| if (unlikely(ret && ret != -EINVAL)) |
| ret = -EIO; |
| |
| return ret; |
| } |
| |
| static inline void handle_partial_read(struct loop_cmd *cmd, long bytes) |
| { |
| if (bytes < 0 || op_is_write(req_op(cmd->rq))) |
| return; |
| |
| if (unlikely(bytes < blk_rq_bytes(cmd->rq))) { |
| struct bio *bio = cmd->rq->bio; |
| |
| bio_advance(bio, bytes); |
| zero_fill_bio(bio); |
| } |
| } |
| |
| static void lo_rw_aio_complete(struct kiocb *iocb, long ret, long ret2) |
| { |
| struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb); |
| struct request *rq = cmd->rq; |
| |
| handle_partial_read(cmd, ret); |
| |
| if (ret > 0) |
| ret = 0; |
| else if (ret < 0) |
| ret = -EIO; |
| |
| blk_mq_complete_request(rq, ret); |
| } |
| |
| static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, |
| loff_t pos, bool rw) |
| { |
| struct iov_iter iter; |
| struct bio_vec *bvec; |
| struct bio *bio = cmd->rq->bio; |
| struct file *file = lo->lo_backing_file; |
| int ret; |
| |
| /* nomerge for loop request queue */ |
| WARN_ON(cmd->rq->bio != cmd->rq->biotail); |
| |
| bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); |
| iov_iter_bvec(&iter, ITER_BVEC | rw, bvec, |
| bio_segments(bio), blk_rq_bytes(cmd->rq)); |
| /* |
| * This bio may be started from the middle of the 'bvec' |
| * because of bio splitting, so offset from the bvec must |
| * be passed to iov iterator |
| */ |
| iter.iov_offset = bio->bi_iter.bi_bvec_done; |
| |
| cmd->iocb.ki_pos = pos; |
| cmd->iocb.ki_filp = file; |
| cmd->iocb.ki_complete = lo_rw_aio_complete; |
| cmd->iocb.ki_flags = IOCB_DIRECT; |
| |
| if (rw == WRITE) |
| ret = file->f_op->write_iter(&cmd->iocb, &iter); |
| else |
| ret = file->f_op->read_iter(&cmd->iocb, &iter); |
| |
| if (ret != -EIOCBQUEUED) |
| cmd->iocb.ki_complete(&cmd->iocb, ret, 0); |
| return 0; |
| } |
| |
| static int do_req_filebacked(struct loop_device *lo, struct request *rq) |
| { |
| struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); |
| loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset; |
| |
| /* |
| * lo_write_simple and lo_read_simple should have been covered |
| * by io submit style function like lo_rw_aio(), one blocker |
| * is that lo_read_simple() need to call flush_dcache_page after |
| * the page is written from kernel, and it isn't easy to handle |
| * this in io submit style function which submits all segments |
| * of the req at one time. And direct read IO doesn't need to |
| * run flush_dcache_page(). |
| */ |
| switch (req_op(rq)) { |
| case REQ_OP_FLUSH: |
| return lo_req_flush(lo, rq); |
| case REQ_OP_DISCARD: |
| return lo_discard(lo, rq, pos); |
| case REQ_OP_WRITE: |
| if (lo->transfer) |
| return lo_write_transfer(lo, rq, pos); |
| else if (cmd->use_aio) |
| return lo_rw_aio(lo, cmd, pos, WRITE); |
| else |
| return lo_write_simple(lo, rq, pos); |
| case REQ_OP_READ: |
| if (lo->transfer) |
| return lo_read_transfer(lo, rq, pos); |
| else if (cmd->use_aio) |
| return lo_rw_aio(lo, cmd, pos, READ); |
| else |
| return lo_read_simple(lo, rq, pos); |
| default: |
| WARN_ON_ONCE(1); |
| return -EIO; |
| break; |
| } |
| } |
| |
| struct switch_request { |
| struct file *file; |
| struct completion wait; |
| }; |
| |
| static inline void loop_update_dio(struct loop_device *lo) |
| { |
| __loop_update_dio(lo, io_is_direct(lo->lo_backing_file) | |
| lo->use_dio); |
| } |
| |
| /* |
| * Do the actual switch; called from the BIO completion routine |
| */ |
| static void do_loop_switch(struct loop_device *lo, struct switch_request *p) |
| { |
| struct file *file = p->file; |
| struct file *old_file = lo->lo_backing_file; |
| struct address_space *mapping; |
| |
| /* if no new file, only flush of queued bios requested */ |
| if (!file) |
| return; |
| |
| mapping = file->f_mapping; |
| mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask); |
| lo->lo_backing_file = file; |
| lo->lo_blocksize = S_ISBLK(mapping->host->i_mode) ? |
| mapping->host->i_bdev->bd_block_size : PAGE_SIZE; |
| lo->old_gfp_mask = mapping_gfp_mask(mapping); |
| mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); |
| loop_update_dio(lo); |
| } |
| |
| /* |
| * loop_switch performs the hard work of switching a backing store. |
| * First it needs to flush existing IO, it does this by sending a magic |
| * BIO down the pipe. The completion of this BIO does the actual switch. |
| */ |
| static int loop_switch(struct loop_device *lo, struct file *file) |
| { |
| struct switch_request w; |
| |
| w.file = file; |
| |
| /* freeze queue and wait for completion of scheduled requests */ |
| blk_mq_freeze_queue(lo->lo_queue); |
| |
| /* do the switch action */ |
| do_loop_switch(lo, &w); |
| |
| /* unfreeze */ |
| blk_mq_unfreeze_queue(lo->lo_queue); |
| |
| return 0; |
| } |
| |
| /* |
| * Helper to flush the IOs in loop, but keeping loop thread running |
| */ |
| static int loop_flush(struct loop_device *lo) |
| { |
| return loop_switch(lo, NULL); |
| } |
| |
| static void loop_reread_partitions(struct loop_device *lo, |
| struct block_device *bdev) |
| { |
| int rc; |
| |
| /* |
| * bd_mutex has been held already in release path, so don't |
| * acquire it if this function is called in such case. |
| * |
| * If the reread partition isn't from release path, lo_refcnt |
| * must be at least one and it can only become zero when the |
| * current holder is released. |
| */ |
| if (!atomic_read(&lo->lo_refcnt)) |
| rc = __blkdev_reread_part(bdev); |
| else |
| rc = blkdev_reread_part(bdev); |
| if (rc) |
| pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n", |
| __func__, lo->lo_number, lo->lo_file_name, rc); |
| } |
| |
| /* |
| * 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) |
| loop_reread_partitions(lo, bdev); |
| 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 = file_path(lo->lo_backing_file, buf, PAGE_SIZE - 1); |
| spin_unlock_irq(&lo->lo_lock); |
| |
| if (IS_ERR_OR_NULL(p)) |
| ret = PTR_ERR(p); |
| else { |
| ret = strlen(p); |
| memmove(buf, p, ret); |
| buf[ret++] = '\n'; |
| buf[ret] = 0; |
| } |
| |
| return ret; |
| } |
| |
| static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf) |
| { |
| return 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"); |
| } |
| |
| static ssize_t loop_attr_dio_show(struct loop_device *lo, char *buf) |
| { |
| int dio = (lo->lo_flags & LO_FLAGS_DIRECT_IO); |
| |
| return sprintf(buf, "%s\n", dio ? "1" : "0"); |
| } |
| |
| LOOP_ATTR_RO(backing_file); |
| LOOP_ATTR_RO(offset); |
| LOOP_ATTR_RO(sizelimit); |
| LOOP_ATTR_RO(autoclear); |
| LOOP_ATTR_RO(partscan); |
| LOOP_ATTR_RO(dio); |
| |
| static struct attribute *loop_attrs[] = { |
| &loop_attr_backing_file.attr, |
| &loop_attr_offset.attr, |
| &loop_attr_sizelimit.attr, |
| &loop_attr_autoclear.attr, |
| &loop_attr_partscan.attr, |
| &loop_attr_dio.attr, |
| NULL, |
| }; |
| |
| static struct attribute_group loop_attribute_group = { |
| .name = "loop", |
| .attrs= loop_attrs, |
| }; |
| |
| static int loop_sysfs_init(struct loop_device *lo) |
| { |
| return sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj, |
| &loop_attribute_group); |
| } |
| |
| static void loop_sysfs_exit(struct loop_device *lo) |
| { |
| sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj, |
| &loop_attribute_group); |
| } |
| |
| static void loop_config_discard(struct loop_device *lo) |
| { |
| struct file *file = lo->lo_backing_file; |
| struct inode *inode = file->f_mapping->host; |
| struct request_queue *q = lo->lo_queue; |
| |
| /* |
| * We use punch hole to reclaim the free space used by the |
| * image a.k.a. discard. However we do not support discard if |
| * encryption is enabled, because it may give an attacker |
| * useful information. |
| */ |
| if ((!file->f_op->fallocate) || |
| lo->lo_encrypt_key_size) { |
| q->limits.discard_granularity = 0; |
| q->limits.discard_alignment = 0; |
| blk_queue_max_discard_sectors(q, 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; |
| blk_queue_max_discard_sectors(q, UINT_MAX >> 9); |
| q->limits.discard_zeroes_data = 1; |
| queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q); |
| } |
| |
| static void loop_unprepare_queue(struct loop_device *lo) |
| { |
| kthread_flush_worker(&lo->worker); |
| kthread_stop(lo->worker_task); |
| } |
| |
| static int loop_prepare_queue(struct loop_device *lo) |
| { |
| kthread_init_worker(&lo->worker); |
| lo->worker_task = kthread_run(kthread_worker_fn, |
| &lo->worker, "loop%d", lo->lo_number); |
| if (IS_ERR(lo->worker_task)) |
| return -ENOMEM; |
| set_user_nice(lo->worker_task, MIN_NICE); |
| return 0; |
| } |
| |
| static int loop_set_fd(struct loop_device *lo, fmode_t mode, |
| struct block_device *bdev, unsigned int arg) |
| { |
| struct file *file, *f; |
| struct inode *inode; |
| struct address_space *mapping; |
| unsigned lo_blocksize; |
| int lo_flags = 0; |
| int error; |
| loff_t size; |
| |
| /* This is safe, since we have a reference from open(). */ |
| __module_get(THIS_MODULE); |
| |
| error = -EBADF; |
| file = fget(arg); |
| if (!file) |
| goto out; |
| |
| error = -EBUSY; |
| if (lo->lo_state != Lo_unbound) |
| goto out_putf; |
| |
| /* Avoid recursion */ |
| f = file; |
| while (is_loop_device(f)) { |
| struct loop_device *l; |
| |
| if (f->f_mapping->host->i_bdev == bdev) |
| goto out_putf; |
| |
| l = f->f_mapping->host->i_bdev->bd_disk->private_data; |
| if (l->lo_state == Lo_unbound) { |
| error = -EINVAL; |
| goto out_putf; |
| } |
| f = l->lo_backing_file; |
| } |
| |
| mapping = file->f_mapping; |
| inode = mapping->host; |
| |
| error = -EINVAL; |
| if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode)) |
| goto out_putf; |
| |
| if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) || |
| !file->f_op->write_iter) |
| lo_flags |= LO_FLAGS_READ_ONLY; |
| |
| lo_blocksize = S_ISBLK(inode->i_mode) ? |
| inode->i_bdev->bd_block_size : PAGE_SIZE; |
| |
| error = -EFBIG; |
| size = get_loop_size(lo, file); |
| if ((loff_t)(sector_t)size != size) |
| goto out_putf; |
| error = loop_prepare_queue(lo); |
| if (error) |
| goto out_putf; |
| |
| error = 0; |
| |
| set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0); |
| |
| lo->use_dio = false; |
| lo->lo_blocksize = lo_blocksize; |
| lo->lo_device = bdev; |
| lo->lo_flags = lo_flags; |
| lo->lo_backing_file = file; |
| lo->transfer = NULL; |
| lo->ioctl = NULL; |
| lo->lo_sizelimit = 0; |
| lo->old_gfp_mask = mapping_gfp_mask(mapping); |
| mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); |
| |
| if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync) |
| blk_queue_write_cache(lo->lo_queue, true, false); |
| |
| loop_update_dio(lo); |
| set_capacity(lo->lo_disk, size); |
| bd_set_size(bdev, size << 9); |
| loop_sysfs_init(lo); |
| /* let user-space know about the new size */ |
| kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); |
| |
| set_blocksize(bdev, lo_blocksize); |
| |
| lo->lo_state = Lo_bound; |
| if (part_shift) |
| lo->lo_flags |= LO_FLAGS_PARTSCAN; |
| if (lo->lo_flags & LO_FLAGS_PARTSCAN) |
| loop_reread_partitions(lo, bdev); |
| |
| /* Grab the block_device to prevent its destruction after we |
| * put /dev/loopXX inode. Later in loop_clr_fd() we bdput(bdev). |
| */ |
| bdgrab(bdev); |
| return 0; |
| |
| out_putf: |
| fput(file); |
| out: |
| /* This is safe: open() is still holding a reference. */ |
| module_put(THIS_MODULE); |
| return error; |
| } |
| |
| static int |
| loop_release_xfer(struct loop_device *lo) |
| { |
| int err = 0; |
| struct loop_func_table *xfer = lo->lo_encryption; |
| |
| if (xfer) { |
| if (xfer->release) |
| err = xfer->release(lo); |
| lo->transfer = NULL; |
| lo->lo_encryption = NULL; |
| module_put(xfer->owner); |
| } |
| return err; |
| } |
| |
| static int |
| loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer, |
| const struct loop_info64 *i) |
| { |
| int err = 0; |
| |
| if (xfer) { |
| struct module *owner = xfer->owner; |
| |
| if (!try_module_get(owner)) |
| return -EINVAL; |
| if (xfer->init) |
| err = xfer->init(lo, i); |
| if (err) |
| module_put(owner); |
| else |
| lo->lo_encryption = xfer; |
| } |
| return err; |
| } |
| |
| static int loop_clr_fd(struct loop_device *lo) |
| { |
| struct file *filp = lo->lo_backing_file; |
| gfp_t gfp = lo->old_gfp_mask; |
| struct block_device *bdev = lo->lo_device; |
| |
| if (lo->lo_state != Lo_bound) |
| return -ENXIO; |
| |
| /* |
| * If we've explicitly asked to tear down the loop device, |
| * and it has an elevated reference count, set it for auto-teardown when |
| * the last reference goes away. This stops $!~#$@ udev from |
| * preventing teardown because it decided that it needs to run blkid on |
| * the loopback device whenever they appear. xfstests is notorious for |
| * failing tests because blkid via udev races with a losetup |
| * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d |
| * command to fail with EBUSY. |
| */ |
| if (atomic_read(&lo->lo_refcnt) > 1) { |
| lo->lo_flags |= LO_FLAGS_AUTOCLEAR; |
| mutex_unlock(&lo->lo_ctl_mutex); |
| return 0; |
| } |
| |
| if (filp == NULL) |
| return -EINVAL; |
| |
| /* freeze request queue during the transition */ |
| blk_mq_freeze_queue(lo->lo_queue); |
| |
| spin_lock_irq(&lo->lo_lock); |
| lo->lo_state = Lo_rundown; |
| lo->lo_backing_file = NULL; |
| spin_unlock_irq(&lo->lo_lock); |
| |
| loop_release_xfer(lo); |
| lo->transfer = NULL; |
| lo->ioctl = NULL; |
| lo->lo_device = NULL; |
| lo->lo_encryption = NULL; |
| lo->lo_offset = 0; |
| lo->lo_sizelimit = 0; |
| lo->lo_encrypt_key_size = 0; |
| memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE); |
| memset(lo->lo_crypt_name, 0, LO_NAME_SIZE); |
| memset(lo->lo_file_name, 0, LO_NAME_SIZE); |
| if (bdev) { |
| bdput(bdev); |
| invalidate_bdev(bdev); |
| } |
| set_capacity(lo->lo_disk, 0); |
| loop_sysfs_exit(lo); |
| if (bdev) { |
| bd_set_size(bdev, 0); |
| /* let user-space know about this change */ |
| kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); |
| } |
| mapping_set_gfp_mask(filp->f_mapping, gfp); |
| lo->lo_state = Lo_unbound; |
| /* This is safe: open() is still holding a reference. */ |
| module_put(THIS_MODULE); |
| blk_mq_unfreeze_queue(lo->lo_queue); |
| |
| if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev) |
| loop_reread_partitions(lo, bdev); |
| lo->lo_flags = 0; |
| if (!part_shift) |
| lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN; |
| loop_unprepare_queue(lo); |
| mutex_unlock(&lo->lo_ctl_mutex); |
| /* |
| * Need not hold lo_ctl_mutex to fput backing file. |
| * Calling fput holding lo_ctl_mutex triggers a circular |
| * lock dependency possibility warning as fput can take |
| * bd_mutex which is usually taken before lo_ctl_mutex. |
| */ |
| fput(filp); |
| return 0; |
| } |
| |
| static int |
| loop_set_status(struct loop_device *lo, const struct loop_info64 *info) |
| { |
| int err; |
| struct loop_func_table *xfer; |
| kuid_t uid = current_uid(); |
| |
| if (lo->lo_encrypt_key_size && |
| !uid_eq(lo->lo_key_owner, uid) && |
| !capable(CAP_SYS_ADMIN)) |
| return -EPERM; |
| if (lo->lo_state != Lo_bound) |
| return -ENXIO; |
| if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE) |
| return -EINVAL; |
| |
| /* I/O need to be drained during transfer transition */ |
| blk_mq_freeze_queue(lo->lo_queue); |
| |
| err = loop_release_xfer(lo); |
| if (err) |
| goto exit; |
| |
| 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) |
| goto exit; |
| |
| if (lo->lo_offset != info->lo_offset || |
| lo->lo_sizelimit != info->lo_sizelimit) |
| if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit)) { |
| err = -EFBIG; |
| goto exit; |
| } |
| |
| loop_config_discard(lo); |
| |
| memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE); |
| memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE); |
| lo->lo_file_name[LO_NAME_SIZE-1] = 0; |
| lo->lo_crypt_name[LO_NAME_SIZE-1] = 0; |
| |
| if (!xfer) |
| xfer = &none_funcs; |
| lo->transfer = xfer->transfer; |
| lo->ioctl = xfer->ioctl; |
| |
| if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) != |
| (info->lo_flags & LO_FLAGS_AUTOCLEAR)) |
| lo->lo_flags ^= LO_FLAGS_AUTOCLEAR; |
| |
| lo->lo_encrypt_key_size = info->lo_encrypt_key_size; |
| lo->lo_init[0] = info->lo_init[0]; |
| lo->lo_init[1] = info->lo_init[1]; |
| if (info->lo_encrypt_key_size) { |
| memcpy(lo->lo_encrypt_key, info->lo_encrypt_key, |
| info->lo_encrypt_key_size); |
| lo->lo_key_owner = uid; |
| } |
| |
| /* update dio if lo_offset or transfer is changed */ |
| __loop_update_dio(lo, lo->use_dio); |
| |
| exit: |
| blk_mq_unfreeze_queue(lo->lo_queue); |
| |
| if (!err && (info->lo_flags & LO_FLAGS_PARTSCAN) && |
| !(lo->lo_flags & LO_FLAGS_PARTSCAN)) { |
| lo->lo_flags |= LO_FLAGS_PARTSCAN; |
| lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN; |
| loop_reread_partitions(lo, lo->lo_device); |
| } |
| |
| return err; |
| } |
| |
| static int |
| loop_get_status(struct loop_device *lo, struct loop_info64 *info) |
| { |
| struct file *file = lo->lo_backing_file; |
| struct kstat stat; |
| int error; |
| |
| if (lo->lo_state != Lo_bound) |
| return -ENXIO; |
| error = vfs_getattr(&file->f_path, &stat); |
| if (error) |
| return error; |
| memset(info, 0, sizeof(*info)); |
| info->lo_number = lo->lo_number; |
| info->lo_device = huge_encode_dev(stat.dev); |
| info->lo_inode = stat.ino; |
| info->lo_rdevice = huge_encode_dev(lo->lo_device ? stat.rdev : stat.dev); |
| info->lo_offset = lo->lo_offset; |
| info->lo_sizelimit = lo->lo_sizelimit; |
| info->lo_flags = lo->lo_flags; |
| memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE); |
| memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE); |
| info->lo_encrypt_type = |
| lo->lo_encryption ? lo->lo_encryption->number : 0; |
| if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) { |
| info->lo_encrypt_key_size = lo->lo_encrypt_key_size; |
| memcpy(info->lo_encrypt_key, lo->lo_encrypt_key, |
| lo->lo_encrypt_key_size); |
| } |
| return 0; |
| } |
| |
| static void |
| loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64) |
| { |
| memset(info64, 0, sizeof(*info64)); |
| info64->lo_number = info->lo_number; |
| info64->lo_device = info->lo_device; |
| info64->lo_inode = info->lo_inode; |
| info64->lo_rdevice = info->lo_rdevice; |
| info64->lo_offset = info->lo_offset; |
| info64->lo_sizelimit = 0; |
| info64->lo_encrypt_type = info->lo_encrypt_type; |
| info64->lo_encrypt_key_size = info->lo_encrypt_key_size; |
| info64->lo_flags = info->lo_flags; |
| info64->lo_init[0] = info->lo_init[0]; |
| info64->lo_init[1] = info->lo_init[1]; |
| if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI) |
| memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE); |
| else |
| memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE); |
| memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE); |
| } |
| |
| static int |
| loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info) |
| { |
| memset(info, 0, sizeof(*info)); |
| info->lo_number = info64->lo_number; |
| info->lo_device = info64->lo_device; |
| info->lo_inode = info64->lo_inode; |
| info->lo_rdevice = info64->lo_rdevice; |
| info->lo_offset = info64->lo_offset; |
| info->lo_encrypt_type = info64->lo_encrypt_type; |
| info->lo_encrypt_key_size = info64->lo_encrypt_key_size; |
| info->lo_flags = info64->lo_flags; |
| info->lo_init[0] = info64->lo_init[0]; |
| info->lo_init[1] = info64->lo_init[1]; |
| if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI) |
| memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE); |
| else |
| memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE); |
| memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE); |
| |
| /* error in case values were truncated */ |
| if (info->lo_device != info64->lo_device || |
| info->lo_rdevice != info64->lo_rdevice || |
| info->lo_inode != info64->lo_inode || |
| info->lo_offset != info64->lo_offset) |
| return -EOVERFLOW; |
| |
| return 0; |
| } |
| |
| static int |
| loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg) |
| { |
| struct loop_info info; |
| struct loop_info64 info64; |
| |
| if (copy_from_user(&info, arg, sizeof (struct loop_info))) |
| return -EFAULT; |
| loop_info64_from_old(&info, &info64); |
| return loop_set_status(lo, &info64); |
| } |
| |
| static int |
| loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg) |
| { |
| struct loop_info64 info64; |
| |
| if (copy_from_user(&info64, arg, sizeof (struct loop_info64))) |
| return -EFAULT; |
| return loop_set_status(lo, &info64); |
| } |
| |
| static int |
| loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) { |
| struct loop_info info; |
| struct loop_info64 info64; |
| int err = 0; |
| |
| if (!arg) |
| err = -EINVAL; |
| if (!err) |
| err = loop_get_status(lo, &info64); |
| if (!err) |
| err = loop_info64_to_old(&info64, &info); |
| if (!err && copy_to_user(arg, &info, sizeof(info))) |
| err = -EFAULT; |
| |
| return err; |
| } |
| |
| static int |
| loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) { |
| struct loop_info64 info64; |
| int err = 0; |
| |
| if (!arg) |
| err = -EINVAL; |
| if (!err) |
| err = loop_get_status(lo, &info64); |
| if (!err && copy_to_user(arg, &info64, sizeof(info64))) |
| err = -EFAULT; |
| |
| return err; |
| } |
| |
| static int loop_set_capacity(struct loop_device *lo, struct block_device *bdev) |
| { |
| if (unlikely(lo->lo_state != Lo_bound)) |
| return -ENXIO; |
| |
| return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit); |
| } |
| |
| static int loop_set_dio(struct loop_device *lo, unsigned long arg) |
| { |
| int error = -ENXIO; |
| if (lo->lo_state != Lo_bound) |
| goto out; |
| |
| __loop_update_dio(lo, !!arg); |
| if (lo->use_dio == !!arg) |
| return 0; |
| error = -EINVAL; |
| out: |
| return error; |
| } |
| |
| static int 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; |
| case LOOP_SET_DIRECT_IO: |
| err = -EPERM; |
| if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) |
| err = loop_set_dio(lo, arg); |
| 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; |
| } |
| |
| atomic_inc(&lo->lo_refcnt); |
| out: |
| mutex_unlock(&loop_index_mutex); |
| return err; |
| } |
| |
| static void __lo_release(struct loop_device *lo) |
| { |
| int err; |
| |
| if (atomic_dec_return(&lo->lo_refcnt)) |
| return; |
| |
| mutex_lock(&lo->lo_ctl_mutex); |
| if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) { |
| /* |
| * In autoclear mode, stop the loop thread |
| * and remove configuration after last close. |
| */ |
| err = loop_clr_fd(lo); |
| if (!err) |
| return; |
| } else { |
| /* |
| * Otherwise keep thread (if running) and config, |
| * but flush possible ongoing bios in thread. |
| */ |
| loop_flush(lo); |
| } |
| |
| mutex_unlock(&lo->lo_ctl_mutex); |
| } |
| |
| static void lo_release(struct gendisk *disk, fmode_t mode) |
| { |
| mutex_lock(&loop_index_mutex); |
| __lo_release(disk->private_data); |
| mutex_unlock(&loop_index_mutex); |
| } |
| |
| static const struct block_device_operations lo_fops = { |
| .owner = THIS_MODULE, |
| .open = lo_open, |
| .release = lo_release, |
| .ioctl = lo_ioctl, |
| #ifdef CONFIG_COMPAT |
| .compat_ioctl = lo_compat_ioctl, |
| #endif |
| }; |
| |
| /* |
| * And now the modules code and kernel interface. |
| */ |
| static int max_loop; |
| module_param(max_loop, int, S_IRUGO); |
| MODULE_PARM_DESC(max_loop, "Maximum number of loop devices"); |
| module_param(max_part, int, S_IRUGO); |
| MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device"); |
| MODULE_LICENSE("GPL"); |
| MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR); |
| |
| int loop_register_transfer(struct loop_func_table *funcs) |
| { |
| unsigned int n = funcs->number; |
| |
| if (n >= MAX_LO_CRYPT || xfer_funcs[n]) |
| return -EINVAL; |
| xfer_funcs[n] = funcs; |
| return 0; |
| } |
| |
| static int unregister_transfer_cb(int id, void *ptr, void *data) |
| { |
| struct loop_device *lo = ptr; |
| struct loop_func_table *xfer = data; |
| |
| mutex_lock(&lo->lo_ctl_mutex); |
| if (lo->lo_encryption == xfer) |
| loop_release_xfer(lo); |
| mutex_unlock(&lo->lo_ctl_mutex); |
| return 0; |
| } |
| |
| int loop_unregister_transfer(int number) |
| { |
| unsigned int n = number; |
| struct loop_func_table *xfer; |
| |
| if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL) |
| return -EINVAL; |
| |
| xfer_funcs[n] = NULL; |
| idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer); |
| return 0; |
| } |
| |
| EXPORT_SYMBOL(loop_register_transfer); |
| EXPORT_SYMBOL(loop_unregister_transfer); |
| |
| static int loop_queue_rq(struct blk_mq_hw_ctx *hctx, |
| const struct blk_mq_queue_data *bd) |
| { |
| struct loop_cmd *cmd = blk_mq_rq_to_pdu(bd->rq); |
| struct loop_device *lo = cmd->rq->q->queuedata; |
| |
| blk_mq_start_request(bd->rq); |
| |
| if (lo->lo_state != Lo_bound) |
| return BLK_MQ_RQ_QUEUE_ERROR; |
| |
| switch (req_op(cmd->rq)) { |
| case REQ_OP_FLUSH: |
| case REQ_OP_DISCARD: |
| cmd->use_aio = false; |
| break; |
| default: |
| cmd->use_aio = lo->use_dio; |
| break; |
| } |
| |
| kthread_queue_work(&lo->worker, &cmd->work); |
| |
| return BLK_MQ_RQ_QUEUE_OK; |
| } |
| |
| static void loop_handle_cmd(struct loop_cmd *cmd) |
| { |
| const bool write = op_is_write(req_op(cmd->rq)); |
| struct loop_device *lo = cmd->rq->q->queuedata; |
| int ret = 0; |
| |
| if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) { |
| ret = -EIO; |
| goto failed; |
| } |
| |
| ret = do_req_filebacked(lo, cmd->rq); |
| failed: |
| /* complete non-aio request */ |
| if (!cmd->use_aio || ret) |
| blk_mq_complete_request(cmd->rq, ret ? -EIO : 0); |
| } |
| |
| static void loop_queue_work(struct kthread_work *work) |
| { |
| struct loop_cmd *cmd = |
| container_of(work, struct loop_cmd, work); |
| |
| loop_handle_cmd(cmd); |
| } |
| |
| static int loop_init_request(void *data, struct request *rq, |
| unsigned int hctx_idx, unsigned int request_idx, |
| unsigned int numa_node) |
| { |
| struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); |
| |
| cmd->rq = rq; |
| kthread_init_work(&cmd->work, loop_queue_work); |
| |
| return 0; |
| } |
| |
| static struct blk_mq_ops loop_mq_ops = { |
| .queue_rq = loop_queue_rq, |
| .init_request = loop_init_request, |
| }; |
| |
| static int loop_add(struct loop_device **l, int i) |
| { |
| struct loop_device *lo; |
| struct gendisk *disk; |
| int err; |
| |
| err = -ENOMEM; |
| lo = kzalloc(sizeof(*lo), GFP_KERNEL); |
| if (!lo) |
| goto out; |
| |
| lo->lo_state = Lo_unbound; |
| |
| /* allocate id, if @id >= 0, we're requesting that specific id */ |
| if (i >= 0) { |
| err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL); |
| if (err == -ENOSPC) |
| err = -EEXIST; |
| } else { |
| err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL); |
| } |
| if (err < 0) |
| goto out_free_dev; |
| i = err; |
| |
| err = -ENOMEM; |
| lo->tag_set.ops = &loop_mq_ops; |
| lo->tag_set.nr_hw_queues = 1; |
| lo->tag_set.queue_depth = 128; |
| lo->tag_set.numa_node = NUMA_NO_NODE; |
| lo->tag_set.cmd_size = sizeof(struct loop_cmd); |
| lo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE; |
| lo->tag_set.driver_data = lo; |
| |
| err = blk_mq_alloc_tag_set(&lo->tag_set); |
| if (err) |
| goto out_free_idr; |
| |
| lo->lo_queue = blk_mq_init_queue(&lo->tag_set); |
| if (IS_ERR_OR_NULL(lo->lo_queue)) { |
| err = PTR_ERR(lo->lo_queue); |
| goto out_cleanup_tags; |
| } |
| lo->lo_queue->queuedata = lo; |
| |
| /* |
| * It doesn't make sense to enable merge because the I/O |
| * submitted to backing file is handled page by page. |
| */ |
| queue_flag_set_unlocked(QUEUE_FLAG_NOMERGES, lo->lo_queue); |
| |
| err = -ENOMEM; |
| disk = lo->lo_disk = alloc_disk(1 << part_shift); |
| if (!disk) |
| goto out_free_queue; |
| |
| /* |
| * Disable partition scanning by default. The in-kernel partition |
| * scanning can be requested individually per-device during its |
| * setup. Userspace can always add and remove partitions from all |
| * devices. The needed partition minors are allocated from the |
| * extended minor space, the main loop device numbers will continue |
| * to match the loop minors, regardless of the number of partitions |
| * used. |
| * |
| * If max_part is given, partition scanning is globally enabled for |
| * all loop devices. The minors for the main loop devices will be |
| * multiples of max_part. |
| * |
| * Note: Global-for-all-devices, set-only-at-init, read-only module |
| * parameteters like 'max_loop' and 'max_part' make things needlessly |
| * complicated, are too static, inflexible and may surprise |
| * userspace tools. Parameters like this in general should be avoided. |
| */ |
| if (!part_shift) |
| disk->flags |= GENHD_FL_NO_PART_SCAN; |
| disk->flags |= GENHD_FL_EXT_DEVT; |
| mutex_init(&lo->lo_ctl_mutex); |
| atomic_set(&lo->lo_refcnt, 0); |
| lo->lo_number = i; |
| spin_lock_init(&lo->lo_lock); |
| disk->major = LOOP_MAJOR; |
| disk->first_minor = i << part_shift; |
| disk->fops = &lo_fops; |
| disk->private_data = lo; |
| disk->queue = lo->lo_queue; |
| sprintf(disk->disk_name, "loop%d", i); |
| add_disk(disk); |
| *l = lo; |
| return lo->lo_number; |
| |
| out_free_queue: |
| blk_cleanup_queue(lo->lo_queue); |
| out_cleanup_tags: |
| blk_mq_free_tag_set(&lo->tag_set); |
| out_free_idr: |
| idr_remove(&loop_index_idr, i); |
| out_free_dev: |
| kfree(lo); |
| out: |
| return err; |
| } |
| |
| static void loop_remove(struct loop_device *lo) |
| { |
| blk_cleanup_queue(lo->lo_queue); |
| del_gendisk(lo->lo_disk); |
| blk_mq_free_tag_set(&lo->tag_set); |
| put_disk(lo->lo_disk); |
| kfree(lo); |
| } |
| |
| static int find_free_cb(int id, void *ptr, void *data) |
| { |
| struct loop_device *lo = ptr; |
| struct loop_device **l = data; |
| |
| if (lo->lo_state == Lo_unbound) { |
| *l = lo; |
| return 1; |
| } |
| return 0; |
| } |
| |
| static int loop_lookup(struct loop_device **l, int i) |
| { |
| struct loop_device *lo; |
| int ret = -ENODEV; |
| |
| if (i < 0) { |
| int err; |
| |
| err = idr_for_each(&loop_index_idr, &find_free_cb, &lo); |
| if (err == 1) { |
| *l = lo; |
| ret = lo->lo_number; |
| } |
| goto out; |
| } |
| |
| /* lookup and return a specific i */ |
| lo = idr_find(&loop_index_idr, i); |
| if (lo) { |
| *l = lo; |
| ret = lo->lo_number; |
| } |
| out: |
| return ret; |
| } |
| |
| static struct kobject *loop_probe(dev_t dev, int *part, void *data) |
| { |
| struct loop_device *lo; |
| struct kobject *kobj; |
| int err; |
| |
| mutex_lock(&loop_index_mutex); |
| err = loop_lookup(&lo, MINOR(dev) >> part_shift); |
| if (err < 0) |
| err = loop_add(&lo, MINOR(dev) >> part_shift); |
| if (err < 0) |
| kobj = NULL; |
| else |
| kobj = get_disk(lo->lo_disk); |
| mutex_unlock(&loop_index_mutex); |
| |
| *part = 0; |
| return kobj; |
| } |
| |
| static long loop_control_ioctl(struct file *file, unsigned int cmd, |
| unsigned long parm) |
| { |
| struct loop_device *lo; |
| int ret = -ENOSYS; |
| |
| mutex_lock(&loop_index_mutex); |
| switch (cmd) { |
| case LOOP_CTL_ADD: |
| ret = loop_lookup(&lo, parm); |
| if (ret >= 0) { |
| ret = -EEXIST; |
| break; |
| } |
| ret = loop_add(&lo, parm); |
| break; |
| case LOOP_CTL_REMOVE: |
| ret = loop_lookup(&lo, parm); |
| if (ret < 0) |
| break; |
| mutex_lock(&lo->lo_ctl_mutex); |
| if (lo->lo_state != Lo_unbound) { |
| ret = -EBUSY; |
| mutex_unlock(&lo->lo_ctl_mutex); |
| break; |
| } |
| if (atomic_read(&lo->lo_refcnt) > 0) { |
| ret = -EBUSY; |
| mutex_unlock(&lo->lo_ctl_mutex); |
| break; |
| } |
| lo->lo_disk->private_data = NULL; |
| mutex_unlock(&lo->lo_ctl_mutex); |
| idr_remove(&loop_index_idr, lo->lo_number); |
| loop_remove(lo); |
| break; |
| case LOOP_CTL_GET_FREE: |
| ret = loop_lookup(&lo, -1); |
| if (ret >= 0) |
| break; |
| ret = loop_add(&lo, -1); |
| } |
| mutex_unlock(&loop_index_mutex); |
| |
| return ret; |
| } |
| |
| static const struct file_operations loop_ctl_fops = { |
| .open = nonseekable_open, |
| .unlocked_ioctl = loop_control_ioctl, |
| .compat_ioctl = loop_control_ioctl, |
| .owner = THIS_MODULE, |
| .llseek = noop_llseek, |
| }; |
| |
| static struct miscdevice loop_misc = { |
| .minor = LOOP_CTRL_MINOR, |
| .name = "loop-control", |
| .fops = &loop_ctl_fops, |
| }; |
| |
| MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR); |
| MODULE_ALIAS("devname:loop-control"); |
| |
| static int __init loop_init(void) |
| { |
| int i, nr; |
| unsigned long range; |
| struct loop_device *lo; |
| int err; |
| |
| err = misc_register(&loop_misc); |
| if (err < 0) |
| return err; |
| |
| part_shift = 0; |
| if (max_part > 0) { |
| part_shift = fls(max_part); |
| |
| /* |
| * Adjust max_part according to part_shift as it is exported |
| * to user space so that user can decide correct minor number |
| * if [s]he want to create more devices. |
| * |
| * Note that -1 is required because partition 0 is reserved |
| * for the whole disk. |
| */ |
| max_part = (1UL << part_shift) - 1; |
| } |
| |
| if ((1UL << part_shift) > DISK_MAX_PARTS) { |
| err = -EINVAL; |
| goto misc_out; |
| } |
| |
| if (max_loop > 1UL << (MINORBITS - part_shift)) { |
| err = -EINVAL; |
| goto misc_out; |
| } |
| |
| /* |
| * If max_loop is specified, create that many devices upfront. |
| * This also becomes a hard limit. If max_loop is not specified, |
| * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module |
| * init time. Loop devices can be requested on-demand with the |
| * /dev/loop-control interface, or be instantiated by accessing |
| * a 'dead' device node. |
| */ |
| if (max_loop) { |
| nr = max_loop; |
| range = max_loop << part_shift; |
| } else { |
| nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT; |
| range = 1UL << MINORBITS; |
| } |
| |
| if (register_blkdev(LOOP_MAJOR, "loop")) { |
| err = -EIO; |
| goto misc_out; |
| } |
| |
| blk_register_region(MKDEV(LOOP_MAJOR, 0), range, |
| THIS_MODULE, loop_probe, NULL, NULL); |
| |
| /* pre-create number of devices given by config or max_loop */ |
| mutex_lock(&loop_index_mutex); |
| for (i = 0; i < nr; i++) |
| loop_add(&lo, i); |
| mutex_unlock(&loop_index_mutex); |
| |
| printk(KERN_INFO "loop: module loaded\n"); |
| return 0; |
| |
| misc_out: |
| misc_deregister(&loop_misc); |
| return err; |
| } |
| |
| static int loop_exit_cb(int id, void *ptr, void *data) |
| { |
| struct loop_device *lo = ptr; |
| |
| loop_remove(lo); |
| return 0; |
| } |
| |
| static void __exit loop_exit(void) |
| { |
| unsigned long range; |
| |
| range = max_loop ? max_loop << part_shift : 1UL << MINORBITS; |
| |
| idr_for_each(&loop_index_idr, &loop_exit_cb, NULL); |
| idr_destroy(&loop_index_idr); |
| |
| blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range); |
| unregister_blkdev(LOOP_MAJOR, "loop"); |
| |
| 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 |