diff options
Diffstat (limited to 'drivers/block/loop.c')
-rw-r--r-- | drivers/block/loop.c | 251 |
1 files changed, 129 insertions, 122 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 4720c7ade0ae..3d806820280e 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -76,6 +76,8 @@ #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); @@ -203,74 +205,6 @@ lo_do_transfer(struct loop_device *lo, int cmd, } /** - * do_lo_send_aops - helper for writing data to a loop device - * - * This is the fast version for backing filesystems which implement the address - * space operations write_begin and write_end. - */ -static int do_lo_send_aops(struct loop_device *lo, struct bio_vec *bvec, - loff_t pos, struct page *unused) -{ - struct file *file = lo->lo_backing_file; /* kudos to NFsckingS */ - struct address_space *mapping = file->f_mapping; - pgoff_t index; - unsigned offset, bv_offs; - int len, ret; - - mutex_lock(&mapping->host->i_mutex); - index = pos >> PAGE_CACHE_SHIFT; - offset = pos & ((pgoff_t)PAGE_CACHE_SIZE - 1); - bv_offs = bvec->bv_offset; - len = bvec->bv_len; - while (len > 0) { - sector_t IV; - unsigned size, copied; - int transfer_result; - struct page *page; - void *fsdata; - - IV = ((sector_t)index << (PAGE_CACHE_SHIFT - 9))+(offset >> 9); - size = PAGE_CACHE_SIZE - offset; - if (size > len) - size = len; - - ret = pagecache_write_begin(file, mapping, pos, size, 0, - &page, &fsdata); - if (ret) - goto fail; - - file_update_time(file); - - transfer_result = lo_do_transfer(lo, WRITE, page, offset, - bvec->bv_page, bv_offs, size, IV); - copied = size; - if (unlikely(transfer_result)) - copied = 0; - - ret = pagecache_write_end(file, mapping, pos, size, copied, - page, fsdata); - if (ret < 0 || ret != copied) - goto fail; - - if (unlikely(transfer_result)) - goto fail; - - bv_offs += copied; - len -= copied; - offset = 0; - index++; - pos += copied; - } - ret = 0; -out: - mutex_unlock(&mapping->host->i_mutex); - return ret; -fail: - ret = -1; - goto out; -} - -/** * __do_lo_send_write - helper for writing data to a loop device * * This helper just factors out common code between do_lo_send_direct_write() @@ -297,10 +231,8 @@ static int __do_lo_send_write(struct file *file, /** * do_lo_send_direct_write - helper for writing data to a loop device * - * This is the fast, non-transforming version for backing filesystems which do - * not implement the address space operations write_begin and write_end. - * It uses the write file operation which should be present on all writeable - * filesystems. + * 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) @@ -316,15 +248,9 @@ static int do_lo_send_direct_write(struct loop_device *lo, /** * do_lo_send_write - helper for writing data to a loop device * - * This is the slow, transforming version for filesystems which do not - * implement the address space operations write_begin and write_end. It - * uses the write file operation which should be present on all writeable - * filesystems. - * - * Using fops->write is slower than using aops->{prepare,commit}_write in the - * transforming case because we need to double buffer the data as we cannot do - * the transformations in place as we do not have direct access to the - * destination pages of the backing file. + * 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) @@ -350,17 +276,16 @@ static int lo_send(struct loop_device *lo, struct bio *bio, loff_t pos) struct page *page = NULL; int i, ret = 0; - do_lo_send = do_lo_send_aops; - if (!(lo->lo_flags & LO_FLAGS_USE_AOPS)) { + 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; - if (lo->transfer != transfer_none) { - page = alloc_page(GFP_NOIO | __GFP_HIGHMEM); - if (unlikely(!page)) - goto fail; - kmap(page); - do_lo_send = do_lo_send_write; - } } + bio_for_each_segment(bvec, bio, i) { ret = do_lo_send(lo, bvec, pos, page); if (ret < 0) @@ -484,6 +409,29 @@ static int do_bio_filebacked(struct loop_device *lo, struct bio *bio) } } + /* + * 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 (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) { @@ -514,7 +462,7 @@ static struct bio *loop_get_bio(struct loop_device *lo) return bio_list_pop(&lo->lo_bio_list); } -static int loop_make_request(struct request_queue *q, struct bio *old_bio) +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); @@ -532,12 +480,11 @@ static int loop_make_request(struct request_queue *q, struct bio *old_bio) loop_add_bio(lo, old_bio); wake_up(&lo->lo_event); spin_unlock_irq(&lo->lo_lock); - return 0; + return; out: spin_unlock_irq(&lo->lo_lock); bio_io_error(old_bio); - return 0; } struct switch_request { @@ -700,7 +647,7 @@ static int loop_change_fd(struct loop_device *lo, struct block_device *bdev, goto out_putf; fput(old_file); - if (max_part > 0) + if (lo->lo_flags & LO_FLAGS_PARTSCAN) ioctl_by_bdev(bdev, BLKRRPART, 0); return 0; @@ -777,16 +724,25 @@ static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf) 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, }; @@ -807,6 +763,35 @@ static void loop_sysfs_exit(struct loop_device *lo) &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 = inode->i_sb->s_blocksize; + 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) { @@ -849,35 +834,23 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode, mapping = file->f_mapping; inode = mapping->host; - if (!(file->f_mode & FMODE_WRITE)) - lo_flags |= LO_FLAGS_READ_ONLY; - error = -EINVAL; - if (S_ISREG(inode->i_mode) || S_ISBLK(inode->i_mode)) { - const struct address_space_operations *aops = mapping->a_ops; - - if (aops->write_begin) - lo_flags |= LO_FLAGS_USE_AOPS; - if (!(lo_flags & LO_FLAGS_USE_AOPS) && !file->f_op->write) - lo_flags |= LO_FLAGS_READ_ONLY; + if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode)) + goto out_putf; - lo_blocksize = S_ISBLK(inode->i_mode) ? - inode->i_bdev->bd_block_size : PAGE_SIZE; + if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) || + !file->f_op->write) + lo_flags |= LO_FLAGS_READ_ONLY; - error = 0; - } else { - goto out_putf; - } + 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) { - error = -EFBIG; + if ((loff_t)(sector_t)size != size) goto out_putf; - } - if (!(mode & FMODE_WRITE)) - lo_flags |= LO_FLAGS_READ_ONLY; + error = 0; set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0); @@ -919,7 +892,9 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode, } lo->lo_state = Lo_bound; wake_up_process(lo->lo_thread); - if (max_part > 0) + if (part_shift) + lo->lo_flags |= LO_FLAGS_PARTSCAN; + if (lo->lo_flags & LO_FLAGS_PARTSCAN) ioctl_by_bdev(bdev, BLKRRPART, 0); return 0; @@ -980,10 +955,11 @@ loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer, return err; } -static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev) +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; @@ -1012,7 +988,6 @@ static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev) lo->lo_offset = 0; lo->lo_sizelimit = 0; lo->lo_encrypt_key_size = 0; - lo->lo_flags = 0; lo->lo_thread = NULL; memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE); memset(lo->lo_crypt_name, 0, LO_NAME_SIZE); @@ -1030,8 +1005,11 @@ static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev) lo->lo_state = Lo_unbound; /* This is safe: open() is still holding a reference. */ module_put(THIS_MODULE); - if (max_part > 0 && bdev) + 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. @@ -1085,6 +1063,7 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) if (figure_loop_size(lo)) 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); @@ -1100,6 +1079,13 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) (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]; @@ -1293,7 +1279,7 @@ static int lo_ioctl(struct block_device *bdev, fmode_t mode, break; case LOOP_CLR_FD: /* loop_clr_fd would have unlocked lo_ctl_mutex on success */ - err = loop_clr_fd(lo, bdev); + err = loop_clr_fd(lo); if (!err) goto out_unlocked; break; @@ -1513,7 +1499,7 @@ static int lo_release(struct gendisk *disk, fmode_t mode) * In autoclear mode, stop the loop thread * and remove configuration after last close. */ - err = loop_clr_fd(lo, NULL); + err = loop_clr_fd(lo); if (!err) goto out_unlocked; } else { @@ -1635,6 +1621,27 @@ static int loop_add(struct loop_device **l, int i) 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; |