* [PATCH] block: Invalidate cache on discard
@ 2017-03-22 14:30 Dmitry Monakhov
2017-03-22 19:05 ` Christoph Hellwig
0 siblings, 1 reply; 2+ messages in thread
From: Dmitry Monakhov @ 2017-03-22 14:30 UTC (permalink / raw)
To: linux-kernel; +Cc: hch, Dmitry Monakhov
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 <dmonakhov@openvz.org>
---
block/ioctl.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/block/ioctl.c b/block/ioctl.c
index 7b88820..d1fea45 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -202,10 +202,15 @@ 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;
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 +221,15 @@ 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);
+
+ mapping = bdev->bd_inode->i_mapping;
+ 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
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] block: Invalidate cache on discard
2017-03-22 14:30 [PATCH] block: Invalidate cache on discard Dmitry Monakhov
@ 2017-03-22 19:05 ` Christoph Hellwig
0 siblings, 0 replies; 2+ messages in thread
From: Christoph Hellwig @ 2017-03-22 19:05 UTC (permalink / raw)
To: Dmitry Monakhov; +Cc: linux-kernel, hch
On Wed, Mar 22, 2017 at 06:30:28PM +0400, Dmitry Monakhov wrote:
> +
> + mapping = bdev->bd_inode->i_mapping;
move this assignment to the declaration of mapping at the beginning
of the function?
Otherwise this looks fine:
Reviewed-by: Christoph Hellwig <hch@lst.de>
^ permalink raw reply [flat|nested] 2+ messages in thread
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