[PATCH 2/3] ext4: make ext4 init/exit match their sequence

Youling Tang
2024-07-11T07:49:44Z

From: Youling Tang <tangyouling@kylinos.cn>

Use init_sequence to ensure that modules init and exit are in sequence
and to simplify the code.

Signed-off-by: Youling Tang <tangyouling@kylinos.cn>
---
fs/ext4/super.c | 175 +++++++++++++++++++++++++-----------------------
1 file changed, 93 insertions(+), 82 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index c682fb927b64..ec1e63facb10 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -7314,103 +7314,114 @@ static struct file_system_type ext4_fs_type = {
};
MODULE_ALIAS_FS("ext4");

-/* Shared across all ext4 file systems */
-wait_queue_head_t ext4__ioend_wq[EXT4_WQ_HASH_SZ];
-
-static int __init ext4_init_fs(void)
+static int register_ext(void)
{
- int i, err;
-
- ratelimit_state_init(&ext4_mount_msg_ratelimit, 30 * HZ, 64);
- ext4_li_info = NULL;
+ register_as_ext3();
+ register_as_ext2();
+ return register_filesystem(&ext4_fs_type);
+}

- /* Build-time check for flags consistency */
- ext4_check_flag_values();
+static void unregister_ext(void)
+{
+ unregister_as_ext2();
+ unregister_as_ext3();
+ unregister_filesystem(&ext4_fs_type);
+}

- for (i = 0; i < EXT4_WQ_HASH_SZ; i++)
- init_waitqueue_head(&ext4__ioend_wq[i]);
+/* Helper structure for long init/exit functions. */
+struct init_sequence {
+ int (*init_func)(void);
+ /* Can be NULL if the init_func doesn't need cleanup. */
+ void (*exit_func)(void);
+};

- err = ext4_init_es();
- if (err)
- return err;
+static const struct init_sequence mod_init_seq[] = {
+ {
+ .init_func = ext4_init_es,
+ .exit_func = ext4_exit_es,
+ }, {
+ .init_func = ext4_init_pending,
+ .exit_func = ext4_exit_pending,
+ }, {
+ .init_func = ext4_init_post_read_processing,
+ .exit_func = ext4_exit_post_read_processing,
+ }, {
+ .init_func = ext4_init_pageio,
+ .exit_func = ext4_exit_pageio,
+ }, {
+ .init_func = ext4_init_system_zone,
+ .exit_func = ext4_exit_system_zone,
+ }, {
+ .init_func = ext4_init_sysfs,
+ .exit_func = ext4_exit_sysfs,
+ }, {
+ .init_func = ext4_init_mballoc,
+ .exit_func = ext4_exit_mballoc,
+ }, {
+ .init_func = init_inodecache,
+ .exit_func = destroy_inodecache,
+ }, {
+ .init_func = ext4_fc_init_dentry_cache,
+ .exit_func = ext4_fc_destroy_dentry_cache,
+ }, {
+ .init_func = register_ext,
+ .exit_func = unregister_ext,
+ }
+};

- err = ext4_init_pending();
- if (err)
- goto out7;
+static bool mod_init_result[ARRAY_SIZE(mod_init_seq)];

- err = ext4_init_post_read_processing();
- if (err)
- goto out6;
+static __always_inline void ext4_exit_ext4_fs(void)
+{
+ int i;

- err = ext4_init_pageio();
- if (err)
- goto out5;
+ for (i = ARRAY_SIZE(mod_init_seq) - 1; i >= 0; i--) {
+ if (!mod_init_result[i])
+ continue;
+ if (mod_init_seq[i].exit_func)
+ mod_init_seq[i].exit_func();
+ mod_init_result[i] = false;
+ }
+}

- err = ext4_init_system_zone();
- if (err)
- goto out4;
+static void __exit ext4_exit_fs(void)
+{
+ ext4_destroy_lazyinit_thread();
+ ext4_exit_ext4_fs();
+}

- err = ext4_init_sysfs();
- if (err)
- goto out3;
+static __always_inline int ext4_init_ext4_fs(void)
+{
+ int ret;
+ int i;

- err = ext4_init_mballoc();
- if (err)
- goto out2;
- err = init_inodecache();
- if (err)
- goto out1;
+ for (i = 0; i < ARRAY_SIZE(mod_init_seq); i++) {
+ ASSERT(!mod_init_result[i]);
+ ret = mod_init_seq[i].init_func();
+ if (ret < 0) {
+ ext4_exit_ext4_fs();
+ return ret;
+ }
+ mod_init_result[i] = true;
+ }
+ return 0;
+}

- err = ext4_fc_init_dentry_cache();
- if (err)
- goto out05;
+/* Shared across all ext4 file systems */
+wait_queue_head_t ext4__ioend_wq[EXT4_WQ_HASH_SZ];

- register_as_ext3();
- register_as_ext2();
- err = register_filesystem(&ext4_fs_type);
- if (err)
- goto out;
+static int __init ext4_init_fs(void)
+{
+ ratelimit_state_init(&ext4_mount_msg_ratelimit, 30 * HZ, 64);
+ ext4_li_info = NULL;

- return 0;
-out:
- unregister_as_ext2();
- unregister_as_ext3();
- ext4_fc_destroy_dentry_cache();
-out05:
- destroy_inodecache();
-out1:
- ext4_exit_mballoc();
-out2:
- ext4_exit_sysfs();
-out3:
- ext4_exit_system_zone();
-out4:
- ext4_exit_pageio();
-out5:
- ext4_exit_post_read_processing();
-out6:
- ext4_exit_pending();
-out7:
- ext4_exit_es();
+ /* Build-time check for flags consistency */
+ ext4_check_flag_values();

- return err;
-}
+ for (int i = 0; i < EXT4_WQ_HASH_SZ; i++)
+ init_waitqueue_head(&ext4__ioend_wq[i]);

-static void __exit ext4_exit_fs(void)
-{
- ext4_destroy_lazyinit_thread();
- unregister_as_ext2();
- unregister_as_ext3();
- unregister_filesystem(&ext4_fs_type);
- ext4_fc_destroy_dentry_cache();
- destroy_inodecache();
- ext4_exit_mballoc();
- ext4_exit_sysfs();
- ext4_exit_system_zone();
- ext4_exit_pageio();
- ext4_exit_post_read_processing();
- ext4_exit_es();
- ext4_exit_pending();
+ return ext4_init_ext4_fs();
}

MODULE_AUTHOR("Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others");
--
2.34.1