btrfs-progs: update kernel status of sha256 accelerated support

Kernels 6.16 and newer always select the accelerated implementation,
don't print the warning if such kernel is running and update
documentation.

Issue: #1049
Signed-off-by: David Sterba <[email protected]>

Author: kdave

Documentation/ch-checksumming.rst

@@ -75,11 +75,15 @@ BLAKE2b          14500        34  builtin, reference impl.
 ========  ============   =======  ================================
 
 Many kernels are configured with SHA256 as built-in and not as a module.
-The accelerated versions are however provided by the modules and must be loaded
+Up to kernel v6.15 the accelerated versions are however provided by the
+modules and must be loaded
 explicitly (:command:`modprobe sha256`) before mounting the filesystem to make use of
 them. You can check in :file:`/sys/fs/btrfs/FSID/checksum` which one is used. If you
 see *sha256-generic*, then you may want to unmount and mount the filesystem
 again. Changing that on a mounted filesystem is not possible.
+
+Since kernel v6.16 the accelereated implementation is always used if available.
+
 Check the file :file:`/proc/crypto`, when the implementation is built-in, you'd find:
 
 .. code-block:: none

mkfs/main.c

@@ -29,6 +29,7 @@
 #include <pthread.h>
 #include <uuid/uuid.h>
 #include <blkid/blkid.h>
+#include <linux/version.h>
 #include "kernel-lib/list.h"
 #include "kernel-lib/list_sort.h"
 #include "kernel-lib/rbtree.h"
@@ -2410,10 +2411,14 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
 		list_all_devices(root, opt_zoned);
 
 		if (mkfs_cfg.csum_type == BTRFS_CSUM_TYPE_SHA256) {
-			printf(
-"NOTE: you may need to manually load kernel module implementing accelerated SHA256 in case\n"
+			u32 kernel_version = get_running_kernel_version();
+
+			if (kernel_version < KERNEL_VERSION(6,16,0)) {
+				printf(
+"NOTE: in kernels < v6.16 you may need to manually load kernel module implementing accelerated SHA256 in case\n"
 "      the generic implementation is built-in, before mount. Check lsmod or /proc/crypto\n\n"
-);
+				);
+			}
 		}
 	}