Merge tag 'xfs-4.18-merge-10' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux

Pull more xfs updates from Darrick Wong:
 "Here's the second round of patches for XFS for 4.18. Most of the
  commits are small cleanups, bug fixes, and continued strengthening of
  metadata verifiers; the bulk of the diff is the conversion of the
  fs/xfs/ tree to use SPDX tags.

  This series has been run through a full xfstests run over the weekend
  and through a quick xfstests run against this morning's master, with
  no major failures reported.

  Summary:

   - Strengthen metadata checking to avoid ASSERTing on bad disk
     contents

   - Validate btree records that are being retrieved for clients

   - Strengthen root inode verification

   - Convert license blurbs to SPDX tags

   - Enable changing DAX flag on directories

   - Fix some writeback deadlocks in reflink

   - Refactor out some old xfs helpers

   - Move type verifiers to a separate file

   - Fix some fuzzer crashes

   - Various other bug fixes"

* tag 'xfs-4.18-merge-10' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: (31 commits)
  xfs: update incore per-AG inode count
  xfs: replace do_mod with native operations
  xfs: don't call xfs_da_shrink_inode with NULL bp
  xfs: clean up MIN/MAX
  xfs: move various type verifiers to common file
  xfs: xfs_reflink_convert_cow() memory allocation deadlock
  xfs: setup VFS i_rwsem lockdep state correctly
  xfs: fix string handling in label get/set functions
  xfs: convert to SPDX license tags
  xfs: validate btree records on retrieval
  xfs: push corruption -> ESTALE conversion to xfs_nfs_get_inode()
  xfs: verify root inode more thoroughly
  xfs: verify COW extent size hint is valid in inode verifier
  xfs: verify extent size hint is valid in inode verifier
  xfs: catch bad stripe alignment configurations
  iomap: fsync swap files before iterating mappings
  xfs: use xfs_trans_getsb in xfs_sync_sb_buf
  xfs: don't assert on corrupted unlinked inode list
  xfs: explicitly pass buffer size to xfs_corruption_error
  xfs: don't assert when on-disk btree pointers are garbage
  ...

1 files changed, 12 insertions, 13 deletions

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index ca6903726689..8eb3ba3d4d00 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -1,19 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (c) 2000-2005 Silicon Graphics, Inc.
  * All Rights Reserved.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it would be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write the Free Software Foundation,
- * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  */
 #include "xfs.h"
 #include "xfs_shared.h"
@@ -543,8 +531,19 @@ xfs_submit_ioend(
 {
 	/* Convert CoW extents to regular */
 	if (!status && ioend->io_type == XFS_IO_COW) {
+		/*
+		 * Yuk. This can do memory allocation, but is not a
+		 * transactional operation so everything is done in GFP_KERNEL
+		 * context. That can deadlock, because we hold pages in
+		 * writeback state and GFP_KERNEL allocations can block on them.
+		 * Hence we must operate in nofs conditions here.
+		 */
+		unsigned nofs_flag;
+
+		nofs_flag = memalloc_nofs_save();
 		status = xfs_reflink_convert_cow(XFS_I(ioend->io_inode),
 				ioend->io_offset, ioend->io_size);
+		memalloc_nofs_restore(nofs_flag);
 	}
 
 	/* Reserve log space if we might write beyond the on-disk inode size. */