For I/O to reflinked blocks we always need to write an entire new file system block, and the code enforces the file system block alignment for the entire file if it has any reflinked blocks. Mirror the larger value reported in the statx in the dio_offset_align in the xfs-specific XFS_IOC_DIOINFO ioctl for the same reason. Don't bother adding a new field for the read alignment to this legacy ioctl as all new users should use statx instead. Signed-off-by: Christoph Hellwig <hch@xxxxxx> Reviewed-by: "Darrick J. Wong" <djwong@xxxxxxxxxx> --- fs/xfs/xfs_ioctl.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c index 0789c18aaa18..f95103325318 100644 --- a/fs/xfs/xfs_ioctl.c +++ b/fs/xfs/xfs_ioctl.c @@ -1204,7 +1204,16 @@ xfs_file_ioctl( struct xfs_buftarg *target = xfs_inode_buftarg(ip); struct dioattr da; - da.d_mem = da.d_miniosz = target->bt_logical_sectorsize; + da.d_mem = target->bt_logical_sectorsize; + + /* + * See xfs_report_dioalign() for an explanation about why this + * reports a value larger than the sector size for COW inodes. + */ + if (xfs_is_cow_inode(ip)) + da.d_miniosz = xfs_inode_alloc_unitsize(ip); + else + da.d_miniosz = target->bt_logical_sectorsize; da.d_maxiosz = INT_MAX & ~(da.d_miniosz - 1); if (copy_to_user(arg, &da, sizeof(da))) -- 2.45.2