ext4: convert mballoc KUnit test to sget_fc()

Same treatment as the extents KUnit test. The mballoc test uses sget()
as a thin "give me an initialized superblock" wrapper for a fake
file_system_type. Move it onto sget_fc() so sget() can go away.

Add a no-op mbt_init_fs_context() so fs_context_for_mount() has
something to call on the fake fs_type. mbt_set() now takes a struct
fs_context * (still a no-op). mbt_ext4_alloc_super_block() allocates
the fc, hands it to sget_fc() and drops the fc reference once the sb
is published.

No functional change.

Link: https://patch.msgid.link/20260529-work-sget-v2-2-57bbe08604e4@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>

diff --git a/fs/ext4/mballoc-test.c b/fs/ext4/mballoc-test.c
index 90ed505fa4b1a3e5b4c5778628b8e813ffcd40a1..d90da44aadbda05ee85ef8515ce6260f962f1dcb 100644 (file)
--- a/fs/ext4/mballoc-test.c
+++ b/fs/ext4/mballoc-test.c
@@ -5,6 +5,7 @@
 
 #include <kunit/test.h>
 #include <kunit/static_stub.h>
+#include <linux/fs_context.h>
 #include <linux/random.h>
 
 #include "ext4.h"
@@ -63,8 +64,14 @@ static void mbt_kill_sb(struct super_block *sb)
        generic_shutdown_super(sb);
 }
 
+static int mbt_init_fs_context(struct fs_context *fc)
+{
+       return 0;
+}
+
 static struct file_system_type mbt_fs_type = {
        .name                   = "mballoc test",
+       .init_fs_context        = mbt_init_fs_context,
        .kill_sb                = mbt_kill_sb,
 };
 
@@ -127,7 +134,7 @@ static void mbt_mb_release(struct super_block *sb)
        kfree(sb->s_bdev);
 }
 
-static int mbt_set(struct super_block *sb, void *data)
+static int mbt_set(struct super_block *sb, struct fs_context *fc)
 {
        return 0;
 }
@@ -136,13 +143,19 @@ static struct super_block *mbt_ext4_alloc_super_block(void)
 {
        struct mbt_ext4_super_block *fsb;
        struct super_block *sb;
+       struct fs_context *fc;
        struct ext4_sb_info *sbi;
 
        fsb = kzalloc_obj(*fsb);
        if (fsb == NULL)
                return NULL;
 
-       sb = sget(&mbt_fs_type, NULL, mbt_set, 0, NULL);
+       fc = fs_context_for_mount(&mbt_fs_type, 0);
+       if (IS_ERR(fc))
+               goto out;
+
+       sb = sget_fc(fc, NULL, mbt_set);
+       put_fs_context(fc);
        if (IS_ERR(sb))
                goto out;