Linux 6.7 compat: handle superblock shrinker member change

In 6.7 the superblock shrinker member s_shrink has changed from being an
embedded struct to a pointer. Detect this, and don't take a reference if
it already is one.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Sponsored-by: https://github.com/sponsors/robn
Closes #15681

diff --git a/config/kernel-shrink.m4 b/config/kernel-shrink.m4
index 0c702153e8c4585957725fe240811243a63c3d25..1c5f753d411c9c360ac2d627a40611a26d4759d6 100644 (file)
--- a/config/kernel-shrink.m4
+++ b/config/kernel-shrink.m4
@@ -19,12 +19,44 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_SUPER_BLOCK_S_SHRINK], [
        ],[])
 ])
 
+dnl #
+dnl # 6.7 API change
+dnl # s_shrink is now a pointer.
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_SRC_SUPER_BLOCK_S_SHRINK_PTR], [
+       ZFS_LINUX_TEST_SRC([super_block_s_shrink_ptr], [
+               #include <linux/fs.h>
+               unsigned long shrinker_cb(struct shrinker *shrink,
+                   struct shrink_control *sc) { return 0; }
+               static struct shrinker shrinker = {
+                       .count_objects = shrinker_cb,
+                       .scan_objects = shrinker_cb,
+                       .seeks = DEFAULT_SEEKS,
+               };
+               static const struct super_block
+                   sb __attribute__ ((unused)) = {
+                       .s_shrink = &shrinker,
+               };
+       ],[])
+])
+
 AC_DEFUN([ZFS_AC_KERNEL_SUPER_BLOCK_S_SHRINK], [
        AC_MSG_CHECKING([whether super_block has s_shrink])
        ZFS_LINUX_TEST_RESULT([super_block_s_shrink], [
                AC_MSG_RESULT(yes)
+               AC_DEFINE(HAVE_SUPER_BLOCK_S_SHRINK, 1,
+                       [have super_block s_shrink])
        ],[
-               ZFS_LINUX_TEST_ERROR([sb->s_shrink()])
+               AC_MSG_RESULT(no)
+               AC_MSG_CHECKING([whether super_block has s_shrink pointer])
+               ZFS_LINUX_TEST_RESULT([super_block_s_shrink_ptr], [
+                       AC_MSG_RESULT(yes)
+                       AC_DEFINE(HAVE_SUPER_BLOCK_S_SHRINK_PTR, 1,
+                               [have super_block s_shrink pointer])
+               ],[
+                       AC_MSG_RESULT(no)
+                       ZFS_LINUX_TEST_ERROR([sb->s_shrink()])
+               ])
        ])
 ])
 
@@ -174,6 +206,7 @@ AC_DEFUN([ZFS_AC_KERNEL_SHRINK_CONTROL_STRUCT], [
 
 AC_DEFUN([ZFS_AC_KERNEL_SRC_SHRINKER], [
        ZFS_AC_KERNEL_SRC_SUPER_BLOCK_S_SHRINK
+       ZFS_AC_KERNEL_SRC_SUPER_BLOCK_S_SHRINK_PTR
        ZFS_AC_KERNEL_SRC_SHRINK_CONTROL_HAS_NID
        ZFS_AC_KERNEL_SRC_SHRINKER_CALLBACK
        ZFS_AC_KERNEL_SRC_SHRINK_CONTROL_STRUCT

diff --git a/module/os/linux/zfs/zfs_vfsops.c b/module/os/linux/zfs/zfs_vfsops.c
index 2792bc027213c3f31dae2dfef0034cea765b6a32..2015c20d734064b241fde7758ba9c6790c826b5d 100644 (file)
--- a/module/os/linux/zfs/zfs_vfsops.c
+++ b/module/os/linux/zfs/zfs_vfsops.c
@@ -1240,12 +1240,18 @@ zfs_prune_aliases(zfsvfs_t *zfsvfs, unsigned long nr_to_scan)
  * and inode caches.  This can occur when the ARC needs to free meta data
  * blocks but can't because they are all pinned by entries in these caches.
  */
+#if defined(HAVE_SUPER_BLOCK_S_SHRINK)
+#define        S_SHRINK(sb)    (&(sb)->s_shrink)
+#elif defined(HAVE_SUPER_BLOCK_S_SHRINK_PTR)
+#define        S_SHRINK(sb)    ((sb)->s_shrink)
+#endif
+
 int
 zfs_prune(struct super_block *sb, unsigned long nr_to_scan, int *objects)
 {
        zfsvfs_t *zfsvfs = sb->s_fs_info;
        int error = 0;
-       struct shrinker *shrinker = &sb->s_shrink;
+       struct shrinker *shrinker = S_SHRINK(sb);
        struct shrink_control sc = {
                .nr_to_scan = nr_to_scan,
                .gfp_mask = GFP_KERNEL,
@@ -1257,7 +1263,7 @@ zfs_prune(struct super_block *sb, unsigned long nr_to_scan, int *objects)
 #if defined(HAVE_SPLIT_SHRINKER_CALLBACK) && \
        defined(SHRINK_CONTROL_HAS_NID) && \
        defined(SHRINKER_NUMA_AWARE)
-       if (sb->s_shrink.flags & SHRINKER_NUMA_AWARE) {
+       if (shrinker->flags & SHRINKER_NUMA_AWARE) {
                *objects = 0;
                for_each_online_node(sc.nid) {
                        *objects += (*shrinker->scan_objects)(shrinker, &sc);