The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7607c44c157d343223510c8ffdf7206fdd2a6213 Mon Sep 17 00:00:00 2001

From: Shin'ichiro Kawasaki shinichiro.kawasaki@wdc.com Date: Tue, 9 Nov 2021 19:47:22 +0900 Subject: [PATCH] block: Hold invalidate_lock in BLKDISCARD ioctl

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.co... Signed-off-by: Jens Axboe axboe@kernel.dk

diff --git a/block/ioctl.c b/block/ioctl.c index d6af0ac97e57..9fa87f64f703 100644 --- a/block/ioctl.c +++ b/block/ioctl.c @@ -113,6 +113,7 @@ 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 inode *inode = bdev->bd_inode; int err;

if (!(mode & FMODE_WRITE)) @@ -135,12 +136,17 @@ static int blk_ioctl_discard(struct block_device *bdev, fmode_t mode, if (start + len > bdev_nr_bytes(bdev)) return -EINVAL;

+ filemap_invalidate_lock(inode->i_mapping); err = truncate_bdev_range(bdev, mode, start, start + len - 1); if (err) - return err; + goto fail; + + err = blkdev_issue_discard(bdev, start >> 9, len >> 9, + GFP_KERNEL, flags);

- return 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,