[PATCH 5/5] xfs: report larger dio alignment for COW inodes

Christoph Hellwig
2025-01-08T08:56:16Z

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@lst.de>
---
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..20f3cf5391c6 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() why report a potential larger than
+ * sector sizevalue here 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