Re: [PATCH 09/14] xfs: Convert double locking of MMAPLOCK to use VFS helpers

Darrick J. Wong
2021-06-07T15:57:22Z

On Mon, Jun 07, 2021 at 04:52:19PM +0200, Jan Kara wrote:
> Convert places in XFS that take MMAPLOCK for two inodes to use helper
> VFS provides for it (filemap_invalidate_down_write_two()). Note that
> this changes lock ordering for MMAPLOCK from inode number based ordering
> to pointer based ordering VFS generally uses.
>
> CC: "Darrick J. Wong" <djwong@kernel.org>
> Reviewed-by: Darrick J. Wong <djwong@kernel.org>
> Signed-off-by: Jan Kara <jack@suse.cz>

Looks straightforward,
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
> fs/xfs/xfs_bmap_util.c | 15 ++++++++-------
> fs/xfs/xfs_inode.c | 37 +++++++++++--------------------------
> 2 files changed, 19 insertions(+), 33 deletions(-)
>
> diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
> index a5e9d7d34023..7421d6ec4def 100644
> --- a/fs/xfs/xfs_bmap_util.c
> +++ b/fs/xfs/xfs_bmap_util.c
> @@ -1582,7 +1582,6 @@ xfs_swap_extents(
> struct xfs_bstat *sbp = &sxp->sx_stat;
> int src_log_flags, target_log_flags;
> int error = 0;
> - int lock_flags;
> uint64_t f;
> int resblks = 0;
> unsigned int flags = 0;
> @@ -1594,8 +1593,8 @@ xfs_swap_extents(
> * do the rest of the checks.
> */
> lock_two_nondirectories(VFS_I(ip), VFS_I(tip));
> - lock_flags = XFS_MMAPLOCK_EXCL;
> - xfs_lock_two_inodes(ip, XFS_MMAPLOCK_EXCL, tip, XFS_MMAPLOCK_EXCL);
> + filemap_invalidate_lock_two(VFS_I(ip)->i_mapping,
> + VFS_I(tip)->i_mapping);
>
> /* Verify that both files have the same format */
> if ((VFS_I(ip)->i_mode & S_IFMT) != (VFS_I(tip)->i_mode & S_IFMT)) {
> @@ -1667,7 +1666,6 @@ xfs_swap_extents(
> * or cancel will unlock the inodes from this point onwards.
> */
> xfs_lock_two_inodes(ip, XFS_ILOCK_EXCL, tip, XFS_ILOCK_EXCL);
> - lock_flags |= XFS_ILOCK_EXCL;
> xfs_trans_ijoin(tp, ip, 0);
> xfs_trans_ijoin(tp, tip, 0);
>
> @@ -1786,13 +1784,16 @@ xfs_swap_extents(
> trace_xfs_swap_extent_after(ip, 0);
> trace_xfs_swap_extent_after(tip, 1);
>
> +out_unlock_ilock:
> + xfs_iunlock(ip, XFS_ILOCK_EXCL);
> + xfs_iunlock(tip, XFS_ILOCK_EXCL);
> out_unlock:
> - xfs_iunlock(ip, lock_flags);
> - xfs_iunlock(tip, lock_flags);
> + filemap_invalidate_unlock_two(VFS_I(ip)->i_mapping,
> + VFS_I(tip)->i_mapping);
> unlock_two_nondirectories(VFS_I(ip), VFS_I(tip));
> return error;
>
> out_trans_cancel:
> xfs_trans_cancel(tp);
> - goto out_unlock;
> + goto out_unlock_ilock;
> }
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index e1854a660809..0468f56f3bbb 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -556,12 +556,10 @@ xfs_lock_inodes(
> }
>
> /*
> - * xfs_lock_two_inodes() can only be used to lock one type of lock at a time -
> - * the mmaplock or the ilock, but not more than one type at a time. If we lock
> - * more than one at a time, lockdep will report false positives saying we have
> - * violated locking orders. The iolock must be double-locked separately since
> - * we use i_rwsem for that. We now support taking one lock EXCL and the other
> - * SHARED.
> + * xfs_lock_two_inodes() can only be used to lock ilock. The iolock and
> + * mmaplock must be double-locked separately since we use i_rwsem and
> + * invalidate_lock for that. We now support taking one lock EXCL and the
> + * other SHARED.
> */
> void
> xfs_lock_two_inodes(
> @@ -579,15 +577,8 @@ xfs_lock_two_inodes(
> ASSERT(hweight32(ip1_mode) == 1);
> ASSERT(!(ip0_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL)));
> ASSERT(!(ip1_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL)));
> - ASSERT(!(ip0_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) ||
> - !(ip0_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)));
> - ASSERT(!(ip1_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) ||
> - !(ip1_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)));
> - ASSERT(!(ip1_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) ||
> - !(ip0_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)));
> - ASSERT(!(ip0_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) ||
> - !(ip1_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)));
> -
> + ASSERT(!(ip0_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)));
> + ASSERT(!(ip1_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)));
> ASSERT(ip0->i_ino != ip1->i_ino);
>
> if (ip0->i_ino > ip1->i_ino) {
> @@ -3750,11 +3741,8 @@ xfs_ilock2_io_mmap(
> ret = xfs_iolock_two_inodes_and_break_layout(VFS_I(ip1), VFS_I(ip2));
> if (ret)
> return ret;
> - if (ip1 == ip2)
> - xfs_ilock(ip1, XFS_MMAPLOCK_EXCL);
> - else
> - xfs_lock_two_inodes(ip1, XFS_MMAPLOCK_EXCL,
> - ip2, XFS_MMAPLOCK_EXCL);
> + filemap_invalidate_lock_two(VFS_I(ip1)->i_mapping,
> + VFS_I(ip2)->i_mapping);
> return 0;
> }
>
> @@ -3764,12 +3752,9 @@ xfs_iunlock2_io_mmap(
> struct xfs_inode *ip1,
> struct xfs_inode *ip2)
> {
> - bool same_inode = (ip1 == ip2);
> -
> - xfs_iunlock(ip2, XFS_MMAPLOCK_EXCL);
> - if (!same_inode)
> - xfs_iunlock(ip1, XFS_MMAPLOCK_EXCL);
> + filemap_invalidate_unlock_two(VFS_I(ip1)->i_mapping,
> + VFS_I(ip2)->i_mapping);
> inode_unlock(VFS_I(ip2));
> - if (!same_inode)
> + if (ip1 != ip2)
> inode_unlock(VFS_I(ip1));
> }
> --
> 2.26.2
>