Workaround issue of Linux vdev_disk.c, (#16678)

in some cases not linearizing buffers with disk sector crossing a page boundary. It is fine for hardware, but somehow required by LUKS. It is not typical for ZFS to produce such buffers, but it may happen if 6KB block is compressed to 4KB, while still having 2KB alignment. Banning the 6KB buffers helps vdevs with ashifh=12. Signed-off-by: Alexander Motin <[email protected]> Sponsored by: iXsystems, Inc. Reviewed-by: Tony Hutter <[email protected]> Reviewed-by: Tino Reichardt <[email protected]>
openzfs · Oct 23, 2024 · aefc2da · aefc2da
1 parent 152ae5c
commit aefc2da
Showing 1 changed file with 14 additions and 0 deletions.
diff --git a/module/zfs/zio.c b/module/zfs/zio.c
@@ -187,6 +187,20 @@ zio_init(void)
 			continue;
 #endif
 
+#if defined(__linux__) && defined(_KERNEL)
+		/*
+		 * Workaround issue of Linux vdev_disk.c, in some cases not
+		 * linearizing buffers with disk sector crossing a page
+		 * boundary. It is fine for hardware, but somehow required by
+		 * LUKS. It is not typical for ZFS to produce such buffers, but
+		 * it may happen if 6KB block is compressed to 4KB, while still
+		 * having 2KB alignment. Banning the 6KB buffers helps vdevs
+		 * with ashifh=12.
+		 */
+		if (size > PAGESIZE && !IS_P2ALIGNED(size, PAGESIZE))
+			continue;
+#endif
+
 		if (IS_P2ALIGNED(size, PAGESIZE))
 			align = PAGESIZE;
 		else