xfs: support STATX_DIOALIGN

Add support for STATX_DIOALIGN to xfs, so that direct I/O alignment
restrictions are exposed to userspace in a generic way.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20220827065851.135710-9-ebiggers@kernel.org

diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 45518b8c613c9a97fd364ccc7fead0fcf91f4771..f51c60d7e2054a42fa7490ec5d32db0a9d90a813 100644 (file)
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -604,6 +604,16 @@ xfs_vn_getattr(
                stat->blksize = BLKDEV_IOSIZE;
                stat->rdev = inode->i_rdev;
                break;
+       case S_IFREG:
+               if (request_mask & STATX_DIOALIGN) {
+                       struct xfs_buftarg      *target = xfs_inode_buftarg(ip);
+                       struct block_device     *bdev = target->bt_bdev;
+
+                       stat->result_mask |= STATX_DIOALIGN;
+                       stat->dio_mem_align = bdev_dma_alignment(bdev) + 1;
+                       stat->dio_offset_align = bdev_logical_block_size(bdev);
+               }
+               fallthrough;
        default:
                stat->blksize = xfs_stat_blksize(ip);
                stat->rdev = 0;