[PATCH 5.15 866/917] block: Hold invalidate_lock in BLKDISCARD ioctl

Greg Kroah-Hartman
2021-11-16T00:37:42Z

From: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>

commit 7607c44c157d343223510c8ffdf7206fdd2a6213 upstream.

When BLKDISCARD ioctl and data read race, the data read leaves stale
page cache. To avoid the stale page cache, hold invalidate_lock of the
block device file mapping. The stale page cache is observed when
blktests test case block/009 is repeated hundreds of times.

This patch can be applied back to the stable kernel version v5.15.y
with slight patch edit. Rework is required for older stable kernels.

Fixes: 351499a172c0 ("block: Invalidate cache on discard v2")
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Cc: stable@vger.kernel.org # v5.15
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20211109104723.835533-2-shinichiro.kawasaki@wdc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
block/ioctl.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -113,6 +113,7 @@ static int blk_ioctl_discard(struct bloc
uint64_t range[2];
uint64_t start, len;
struct request_queue *q = bdev_get_queue(bdev);
+ struct inode *inode = bdev->bd_inode;
int err;

if (!(mode & FMODE_WRITE))
@@ -135,12 +136,17 @@ static int blk_ioctl_discard(struct bloc
if (start + len > i_size_read(bdev->bd_inode))
return -EINVAL;

+ filemap_invalidate_lock(inode->i_mapping);
err = truncate_bdev_range(bdev, mode, start, start + len - 1);
if (err)
- return err;
+ goto fail;

- return blkdev_issue_discard(bdev, start >> 9, len >> 9,
- GFP_KERNEL, flags);
+ err = blkdev_issue_discard(bdev, start >> 9, len >> 9,
+ GFP_KERNEL, flags);
+
+fail:
+ filemap_invalidate_unlock(inode->i_mapping);
+ return err;
}

static int blk_ioctl_zeroout(struct block_device *bdev, fmode_t mode,