On Tue, Jan 23, 2018 at 06:18:03PM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> Before we share blocks between files, we need to break the pnfs leases
> on the layout before we start slicing and dicing the block map.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
> fs/xfs/xfs_reflink.c | 48 +++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 47 insertions(+), 1 deletion(-)
>
>
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index 47aea2e..f89a725 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -1245,6 +1245,50 @@ xfs_reflink_remap_blocks(
> }
>
> /*
> + * Grab the exclusive iolock for a data copy from src to dest, making
> + * sure to abide vfs locking order (lowest pointer value goes first) and
> + * breaking the pnfs layout leases on dest before proceeding. The loop
> + * is needed because we cannot call the blocking break_layout() with the
> + * src iolock held, and therefore have to back out both locks.
> + */
> +static int
> +xfs_iolock_two_inodes_and_break_layout(
> + struct inode *src,
> + struct inode *dest)
> +{
> + bool src_first = src < dest;
> + bool src_last = src > dest;
> + int error;
> +
> +retry:
> + if (src_first) {
> + inode_lock(src);
> + inode_lock_nested(dest, I_MUTEX_NONDIR2);
> + } else {
> + inode_lock(dest);
> + }
> +
> + error = break_layout(dest, false);
> + if (error == -EWOULDBLOCK) {
> + inode_unlock(dest);
> + if (src_first)
> + inode_unlock(src);
> + error = break_layout(dest, true);
> + if (error)
> + return error;
> + goto retry;
> + } else if (error) {
> + inode_unlock(dest);
> + if (src_first)
> + inode_unlock(src);
> + return error;
> + }
> + if (src_last)
> + inode_lock_nested(src, I_MUTEX_NONDIR2);
> + return 0;
> +}
> +
> +/*
> * Link a range of blocks from one file to another.
> */
> int
> @@ -1274,7 +1318,9 @@ xfs_reflink_remap_range(
> return -EIO;
>
> /* Lock both files against IO */
> - lock_two_nondirectories(inode_in, inode_out);
> + ret = xfs_iolock_two_inodes_and_break_layout(inode_in, inode_out);
> + if (ret)
> + return ret;
> if (same_inode)
> xfs_ilock(src, XFS_MMAPLOCK_EXCL);
> else
>
> --
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