On 9/29/23 15:49, Eric Biggers wrote:

On Fri, Sep 29, 2023 at 10:27:08AM +0000, John Garry wrote:

quoted

diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h
index 7cab2c65d3d7..c99d7cac2aa6 100644
--- a/include/uapi/linux/stat.h
+++ b/include/uapi/linux/stat.h

@@ -127,7 +127,10 @@ struct statx {
  	__u32	stx_dio_mem_align;	/* Memory buffer alignment for direct I/O */
  	__u32	stx_dio_offset_align;	/* File offset alignment for direct I/O */
  	/* 0xa0 */
-	__u64	__spare3[12];	/* Spare space for future expansion */
+	__u32	stx_atomic_write_unit_max;
+	__u32	stx_atomic_write_unit_min;

Maybe min first and then max?  That seems a bit more natural, and a lot of the
code you've written handle them in that order.

quoted

+#define STATX_ATTR_WRITE_ATOMIC		0x00400000 /* File supports atomic write operations */

How would this differ from stx_atomic_write_unit_min != 0?

Is it even possible that stx_atomic_write_unit_min == 0? My understanding
is that all Linux filesystems rely on the assumption that writing a single
logical block either succeeds or does not happen, even if a power failure
occurs between writing and reading a logical block.

Thanks,

Bart.