diff options
| -rw-r--r-- | drivers/block/loop.c | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 76c8da78212b..936cac3c3126 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -75,6 +75,7 @@ #include <linux/kthread.h> #include <linux/splice.h> #include <linux/sysfs.h> +#include <linux/falloc.h> #include <asm/uaccess.h> @@ -484,6 +485,29 @@ 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) { @@ -814,6 +838,35 @@ 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) { @@ -1090,6 +1143,7 @@ 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); |