Messages in this thread | | | Subject | Re: [f2fs-dev] [PATCH] f2fs: add symbolic link to kobject in sysfs | From | Chao Yu <> | Date | Wed, 1 Jul 2020 14:36:03 +0800 |
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Hi Daeho,
On 2020/6/30 8:56, Daeho Jeong wrote: > 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. It will > provide easy access to sysfs node even if not knowing the > specific device node name like sda19 and dm-3.
Just out of curiosity, if we mount/umount as below:
mount /dev/zram0 /mnt/f2fs0 mount /dev/zram1 /mnt/f2fs1 umount /mnt/f2fs0 mount /dev/zram0 /mnt/f2fs0
Shouldn't sysfs structure be: mount_2 -> zram0 mount_1 -> zram1 zram0 zram1
Then we can know zram0 is mounted after zram1?
However the result shows: mount_0 -> zram0 mount_1 -> zram1 zram0 zram1
Thanks,
> > 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 ab40e1f89f23..64bbe0b3b830 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 { > @@ -906,6 +907,9 @@ int __init f2fs_init_sysfs(void) > } else { > f2fs_proc_root = proc_mkdir("fs/f2fs", NULL); > } > + > + ida_init(&f2fs_mount_ida); > + > return ret; > } > > @@ -915,6 +919,7 @@ 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) > @@ -926,12 +931,22 @@ 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); > > @@ -946,6 +961,12 @@ 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) > @@ -957,6 +978,8 @@ 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); > } >
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