diff mbox series

[5.4,CANDIDATE,4/6] xfs: use MMAPLOCK around filemap_map_pages()

Message ID 20221110063608.629732-5-chandan.babu@oracle.com (mailing list archive)
State Superseded
Headers show
Series xfs stable candidate patches for 5.4.y (from v5.9) | expand

Commit Message

Chandan Babu R Nov. 10, 2022, 6:36 a.m. UTC 
From: Dave Chinner <dchinner@redhat.com>

commit cd647d5651c0b0deaa26c1acb9e1789437ba9bc7 upstream.

The page faultround path ->map_pages is implemented in XFS via
filemap_map_pages(). This function checks that pages found in page
cache lookups have not raced with truncate based invalidation by
checking page->mapping is correct and page->index is within EOF.

However, we've known for a long time that this is not sufficient to
protect against races with invalidations done by operations that do
not change EOF. e.g. hole punching and other fallocate() based
direct extent manipulations. The way we protect against these
races is we wrap the page fault operations in a XFS_MMAPLOCK_SHARED
lock so they serialise against fallocate and truncate before calling
into the filemap function that processes the fault.

Do the same for XFS's ->map_pages implementation to close this
potential data corruption issue.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Chandan Babu R <chandan.babu@oracle.com>
---
 fs/xfs/xfs_file.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index c67fab2c37c5..b651715da8c6 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1267,10 +1267,23 @@  xfs_filemap_pfn_mkwrite(
 	return __xfs_filemap_fault(vmf, PE_SIZE_PTE, true);
 }
 
+static void
+xfs_filemap_map_pages(
+	struct vm_fault		*vmf,
+	pgoff_t			start_pgoff,
+	pgoff_t			end_pgoff)
+{
+	struct inode		*inode = file_inode(vmf->vma->vm_file);
+
+	xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
+	filemap_map_pages(vmf, start_pgoff, end_pgoff);
+	xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED);
+}
+
 static const struct vm_operations_struct xfs_file_vm_ops = {
 	.fault		= xfs_filemap_fault,
 	.huge_fault	= xfs_filemap_huge_fault,
-	.map_pages	= filemap_map_pages,
+	.map_pages	= xfs_filemap_map_pages,
 	.page_mkwrite	= xfs_filemap_page_mkwrite,
 	.pfn_mkwrite	= xfs_filemap_pfn_mkwrite,
 };