Commit 851c4c96 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Carlos Maiolino
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xfs: implement XFS_IOC_DIOINFO in terms of vfs_getattr 



Use the direct I/O alignment reporting from ->getattr instead of
reimplementing it.  This exposes the relaxation of the memory
alignment in the XFS_IOC_DIOINFO info and ensure the information will
stay in sync.  Note that randholes.c in xfstests has a bug where it
incorrectly fails when the required memory alignment is smaller than the
pointer size.  Round up the reported value as there is a fair chance that
this code got copied into various applications.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarCarlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: default avatarCarlos Maiolino <cem@kernel.org>
parent 0239bd9f

fs/xfs/xfs_ioctl.c

+9 −9
Original line number Diff line number Diff line
@@ -1203,21 +1203,21 @@ xfs_file_ioctl( 
				current->comm);

		return -ENOTTY;

	case XFS_IOC_DIOINFO: {

		struct xfs_buftarg	*target = xfs_inode_buftarg(ip);

		struct kstat		st;

		struct dioattr		da;



		da.d_mem = target->bt_logical_sectorsize;

		error = vfs_getattr(&filp->f_path, &st, STATX_DIOALIGN, 0);

		if (error)

			return error;



		/*

		 * See xfs_report_dioalign() for an explanation about why this

		 * reports a value larger than the sector size for COW inodes.

		 * Some userspace directly feeds the return value to

		 * posix_memalign, which fails for values that are smaller than

		 * the pointer size.  Round up the value to not break userspace.

		 */

		if (xfs_is_cow_inode(ip))

			da.d_miniosz = xfs_inode_alloc_unitsize(ip);

		else

			da.d_miniosz = target->bt_logical_sectorsize;

		da.d_mem = roundup(st.dio_mem_align, sizeof(void *));

		da.d_miniosz = st.dio_offset_align;

		da.d_maxiosz = INT_MAX & ~(da.d_miniosz - 1);



		if (copy_to_user(arg, &da, sizeof(da)))

			return -EFAULT;

		return 0;