fs/dax: always remove DAX page-cache entries when breaking layouts

Prior to any truncation operations file systems call dax_break_mapping()
to ensure pages in the range are not under going DMA.  Later DAX
page-cache entries will be removed by truncate_folio_batch_exceptionals()
in the generic page-cache code.

However this makes it possible for folios to be removed from the
page-cache even though they are still DMA busy if the file-system hasn't
called dax_break_mapping().  It also means they can never be waited on in
future because FS DAX will lose track of them once the page-cache entry
has been deleted.

Instead it is better to delete the FS DAX entry when the file-system calls
dax_break_mapping() as part of it's truncate operation.  This ensures only
idle pages can be removed from the FS DAX page-cache and makes it easy to
detect if a file-system hasn't called dax_break_mapping() prior to a
truncate operation.

Link: https://lkml.kernel.org/r/3be6115eaaa8d28fee37fcba3287be4f226a7d24.1740713401.git-series.apopple@nvidia.com
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Alison Schofield <alison.schofield@intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Asahi Lina <lina@asahilina.net>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Chunyan Zhang <zhang.lyra@gmail.com>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: linmiaohe <linmiaohe@huawei.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Matthew Wilcow (Oracle) <willy@infradead.org>
Cc: Michael "Camp Drill Sergeant" Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Ted Ts'o <tytso@mit.edu>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 2 insertions, 3 deletions

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index d4f07e02b28b..80083376a1d0 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -2735,7 +2735,6 @@ xfs_mmaplock_two_inodes_and_break_dax_layout(
 	struct xfs_inode	*ip2)
 {
 	int			error;
-	struct page		*page;
 
 	if (ip1->i_ino > ip2->i_ino)
 		swap(ip1, ip2);
@@ -2759,8 +2758,8 @@ again:
 	 * need to unlock & lock the XFS_MMAPLOCK_EXCL which is not suitable
 	 * for this nested lock case.
 	 */
-	page = dax_layout_busy_page(VFS_I(ip2)->i_mapping);
-	if (!dax_page_is_idle(page)) {
+	error = dax_break_layout(VFS_I(ip2), 0, -1, NULL);
+	if (error) {
 		xfs_iunlock(ip2, XFS_MMAPLOCK_EXCL);
 		xfs_iunlock(ip1, XFS_MMAPLOCK_EXCL);
 		goto again;