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Message-ID: <20210525214130.GP202121@locust>
Date: Tue, 25 May 2021 14:41:30 -0700
From: "Darrick J. Wong" <djwong@...nel.org>
To: Jan Kara <jack@...e.cz>
Cc: linux-fsdevel@...r.kernel.org,
Christoph Hellwig <hch@...radead.org>,
Dave Chinner <david@...morbit.com>, ceph-devel@...r.kernel.org,
Chao Yu <yuchao0@...wei.com>,
Damien Le Moal <damien.lemoal@....com>,
"Darrick J. Wong" <darrick.wong@...cle.com>,
Jaegeuk Kim <jaegeuk@...nel.org>,
Jeff Layton <jlayton@...nel.org>,
Johannes Thumshirn <jth@...nel.org>,
linux-cifs@...r.kernel.org, linux-ext4@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net, linux-mm@...ck.org,
linux-xfs@...r.kernel.org, Miklos Szeredi <miklos@...redi.hu>,
Steve French <sfrench@...ba.org>, Ted Tso <tytso@....edu>,
Matthew Wilcox <willy@...radead.org>
Subject: Re: [PATCH 08/13] xfs: Convert double locking of MMAPLOCK to use VFS
helpers
On Tue, May 25, 2021 at 03:50:45PM +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.
>
> Signed-off-by: Jan Kara <jack@...e.cz>
Reviewed-by: Darrick J. Wong <djwong@...nel.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..8a5cede59f3f 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_down_write_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_up_write_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 53bb5fc33621..11616c9b37f8 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -537,12 +537,10 @@ 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(
> @@ -560,15 +558,8 @@ 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) {
> @@ -3731,11 +3722,8 @@ 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_down_write_two(VFS_I(ip1)->i_mapping,
> + VFS_I(ip2)->i_mapping);
> return 0;
> }
>
> @@ -3745,12 +3733,9 @@ 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_up_write_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
>
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