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: Christoph Hellwig <hch@xxxxxx>
---
Changes since v1:
- update the comment
fs/xfs/xfs_ioctl.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index e1051a530a50..ff0a8dc74948 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -1209,21 +1209,21 @@ 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;
--
2.47.2
