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

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