[PATCH 08/13] xfs: Convert double locking of MMAPLOCK to use VFS helpers

Jan Kara
2021-05-25T13:51:23Z

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@suse.cz>
---
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