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 Acked-by: Darrick J. Wong djwong@kernel.org Signed-off-by: Chandan Babu R chandan.babu@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/xfs/xfs_file.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-)
--- 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, };