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
---
block/ioctl.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
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,
--
2.33.1
