It is reasonable drop page cache on discard, otherwise that pages may
be written by writeback second later, so thin provision devices will
not be happy. This seems to be a security leak in case of secure discard case.
Also add check for queue_discard flag on early stage.
Signed-off-by: Dmitry Monakhov <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
---
block/ioctl.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/block/ioctl.c b/block/ioctl.c
index 7b88820..336610d 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -202,10 +202,16 @@ static int blk_ioctl_discard(struct block_device *bdev, fmode_t mode,
{
uint64_t range[2];
uint64_t start, len;
+ struct request_queue *q = bdev_get_queue(bdev);
+ struct address_space *mapping = bdev->bd_inode->i_mapping;
+
if (!(mode & FMODE_WRITE))
return -EBADF;
+ if (!blk_queue_discard(q))
+ return -EOPNOTSUPP;
+
if (copy_from_user(range, (void __user *)arg, sizeof(range)))
return -EFAULT;
@@ -216,12 +222,12 @@ static int blk_ioctl_discard(struct block_device *bdev, fmode_t mode,
return -EINVAL;
if (len & 511)
return -EINVAL;
- start >>= 9;
- len >>= 9;
- if (start + len > (i_size_read(bdev->bd_inode) >> 9))
+ if (start + len > i_size_read(bdev->bd_inode))
return -EINVAL;
- return blkdev_issue_discard(bdev, start, len, GFP_KERNEL, flags);
+ truncate_inode_pages_range(mapping, start, start + len);
+ return blkdev_issue_discard(bdev, start >> 9, len >> 9,
+ GFP_KERNEL, flags);
}
static int blk_ioctl_zeroout(struct block_device *bdev, fmode_t mode,
--
2.9.3