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

[Greg Kroah-Hartman]

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

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@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v5.15
Reviewed-by: Jan Kara <jack@xxxxxxx>
Link: https://lore.kernel.org/r/20211109104723.835533-2-shinichiro.kawasaki@xxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 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,