[PATCH v2] f2fs: add symbolic link to kobject in sysfs

Daeho Jeong
2020-07-03T04:19:42Z

From: Daeho Jeong <daehojeong@google.com>

Added a symbolic link to directory of sysfs. It will
create a symbolic link such as "mount_0" and "mount_1" to
each f2fs mount in the order of mounting filesystem. But
once one mount point was umounted, that sequential number
@x in "mount_@x" could be reused by later newly mounted
point. It will provide easy access to sysfs node even if
not knowing the specific device node name like sda19 and
dm-3.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
---
fs/f2fs/f2fs.h | 4 ++++
fs/f2fs/sysfs.c | 31 +++++++++++++++++++++++++++----
2 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 4b28fd42fdbc..7d6c5f8ce16b 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1419,6 +1419,8 @@ struct decompress_io_ctx {
#define MAX_COMPRESS_LOG_SIZE 8
#define MAX_COMPRESS_WINDOW_SIZE ((PAGE_SIZE) << MAX_COMPRESS_LOG_SIZE)

+#define MOUNT_NAME_SIZE 20
+
struct f2fs_sb_info {
struct super_block *sb; /* pointer to VFS super block */
struct proc_dir_entry *s_proc; /* proc entry */
@@ -1599,6 +1601,8 @@ struct f2fs_sb_info {
/* For sysfs suppport */
struct kobject s_kobj;
struct completion s_kobj_unregister;
+ int s_mount_id;
+ char s_mount_name[MOUNT_NAME_SIZE];

/* For shrinker support */
struct list_head s_list;
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index 2a140657fc4d..703d9f460d03 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -18,6 +18,7 @@
#include <trace/events/f2fs.h>

static struct proc_dir_entry *f2fs_proc_root;
+static struct ida f2fs_mount_ida;

/* Sysfs support for f2fs */
enum {
@@ -908,6 +909,9 @@ int __init f2fs_init_sysfs(void)
} else {
f2fs_proc_root = proc_mkdir("fs/f2fs", NULL);
}
+
+ ida_init(&f2fs_mount_ida);
+
return ret;
}

@@ -917,6 +921,7 @@ void f2fs_exit_sysfs(void)
kset_unregister(&f2fs_kset);
remove_proc_entry("fs/f2fs", NULL);
f2fs_proc_root = NULL;
+ ida_destroy(&f2fs_mount_ida);
}

int f2fs_register_sysfs(struct f2fs_sb_info *sbi)
@@ -928,12 +933,22 @@ int f2fs_register_sysfs(struct f2fs_sb_info *sbi)
init_completion(&sbi->s_kobj_unregister);
err = kobject_init_and_add(&sbi->s_kobj, &f2fs_sb_ktype, NULL,
"%s", sb->s_id);
- if (err) {
- kobject_put(&sbi->s_kobj);
- wait_for_completion(&sbi->s_kobj_unregister);
- return err;
+ if (err)
+ goto err1;
+
+ sbi->s_mount_id = ida_simple_get(&f2fs_mount_ida, 0, 0, GFP_KERNEL);
+ if (sbi->s_mount_id < 0) {
+ err = sbi->s_mount_id;
+ goto err1;
}

+ snprintf(sbi->s_mount_name, MOUNT_NAME_SIZE, "mount_%d",
+ sbi->s_mount_id);
+ err = sysfs_create_link(&f2fs_kset.kobj, &sbi->s_kobj,
+ sbi->s_mount_name);
+ if (err)
+ goto err2;
+
if (f2fs_proc_root)
sbi->s_proc = proc_mkdir(sb->s_id, f2fs_proc_root);

@@ -948,6 +963,12 @@ int f2fs_register_sysfs(struct f2fs_sb_info *sbi)
victim_bits_seq_show, sb);
}
return 0;
+err2:
+ ida_simple_remove(&f2fs_mount_ida, sbi->s_mount_id);
+err1:
+ kobject_put(&sbi->s_kobj);
+ wait_for_completion(&sbi->s_kobj_unregister);
+ return err;
}

void f2fs_unregister_sysfs(struct f2fs_sb_info *sbi)
@@ -959,6 +980,8 @@ void f2fs_unregister_sysfs(struct f2fs_sb_info *sbi)
remove_proc_entry("victim_bits", sbi->s_proc);
remove_proc_entry(sbi->sb->s_id, f2fs_proc_root);
}
+ sysfs_remove_link(&f2fs_kset.kobj, sbi->s_mount_name);
+ ida_simple_remove(&f2fs_mount_ida, sbi->s_mount_id);
kobject_del(&sbi->s_kobj);
kobject_put(&sbi->s_kobj);
}
--
2.27.0.383.g050319c2ae-goog