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.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/ioctl.c b/block/ioctl.c
index d6af0ac..9fa87f6 100644 (file)
--- 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,