On Mon 22-02-21 10:48:09, Jan Kara wrote:
> Commit 384d87ef2c95 ("block: Do not discard buffers under a mounted
> filesystem") made paths issuing discard or zeroout requests to the
> underlying device try to grab block device in exclusive mode. If that
> failed we returned EBUSY to userspace. This however caused unexpected
> fallout in userspace where e.g. FUSE filesystems issue discard requests
> from userspace daemons although the device is open exclusively by the
> kernel. Also shrinking of logical volume by LVM issues discard requests
> to a device which may be claimed exclusively because there's another LV
> on the same PV. So to avoid these userspace regressions, fall back to
> invalidate_inode_pages2_range() instead of returning EBUSY to userspace
> and return EBUSY only of that call fails as well (meaning that there's
> indeed someone using the particular device range we are trying to
> discard).
>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=211167
> Fixes: 384d87ef2c95 ("block: Do not discard buffers under a mounted filesystem")
> CC: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Jan Kara <jack@xxxxxxx>
Before I forget: I'd like to add two tested by tags to give credit to
people who helped with testing.
Tested-by: Richard W.M. Jones <rjones@xxxxxxxxxx>
Tested-by: Andreas Klauer <Andreas.Klauer@xxxxxxxxxxxxxx>
Honza
> ---
> fs/block_dev.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index 235b5042672e..c33151020bcd 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -118,13 +118,22 @@ int truncate_bdev_range(struct block_device *bdev, fmode_t mode,
> if (!(mode & FMODE_EXCL)) {
> int err = bd_prepare_to_claim(bdev, truncate_bdev_range);
> if (err)
> - return err;
> + goto invalidate;
> }
>
> truncate_inode_pages_range(bdev->bd_inode->i_mapping, lstart, lend);
> if (!(mode & FMODE_EXCL))
> bd_abort_claiming(bdev, truncate_bdev_range);
> return 0;
> +
> +invalidate:
> + /*
> + * Someone else has handle exclusively open. Try invalidating instead.
> + * The 'end' argument is inclusive so the rounding is safe.
> + */
> + return invalidate_inode_pages2_range(bdev->bd_inode->i_mapping,
> + lstart >> PAGE_SHIFT,
> + lend >> PAGE_SHIFT);
> }
> EXPORT_SYMBOL(truncate_bdev_range);
>
> --
> 2.26.2
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
