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    Subject[PATCH 02/13] vfs: keep list of mounts for each superblock
    Date
    From: Miklos Szeredi <mszeredi@suse.cz>

    Keep track of vfsmounts belonging to a superblock. List is protected
    by vfsmount_lock.

    Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
    Tested-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
    ---
    fs/namespace.c | 10 ++++++++++
    fs/super.c | 2 ++
    include/linux/fs.h | 1 +
    include/linux/mount.h | 1 +
    4 files changed, 14 insertions(+), 0 deletions(-)

    diff --git a/fs/namespace.c b/fs/namespace.c
    index b4febb2..ccbec4e 100644
    --- a/fs/namespace.c
    +++ b/fs/namespace.c
    @@ -696,6 +696,11 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void
    mnt->mnt_sb = root->d_sb;
    mnt->mnt_mountpoint = mnt->mnt_root;
    mnt->mnt_parent = mnt;
    +
    + br_write_lock(vfsmount_lock);
    + list_add_tail(&mnt->mnt_instance, &mnt->mnt_sb->s_mounts);
    + br_write_unlock(vfsmount_lock);
    +
    return mnt;
    }
    EXPORT_SYMBOL_GPL(vfs_kern_mount);
    @@ -745,6 +750,10 @@ static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root,
    if (!list_empty(&old->mnt_expire))
    list_add(&mnt->mnt_expire, &old->mnt_expire);
    }
    +
    + br_write_lock(vfsmount_lock);
    + list_add_tail(&mnt->mnt_instance, &mnt->mnt_sb->s_mounts);
    + br_write_unlock(vfsmount_lock);
    }
    return mnt;

    @@ -805,6 +814,7 @@ put_again:
    acct_auto_close_mnt(mnt);
    goto put_again;
    }
    + list_del(&mnt->mnt_instance);
    br_write_unlock(vfsmount_lock);
    mntfree(mnt);
    }
    diff --git a/fs/super.c b/fs/super.c
    index 14948d6..a021ca2 100644
    --- a/fs/super.c
    +++ b/fs/super.c
    @@ -142,6 +142,7 @@ static struct super_block *alloc_super(struct file_system_type *type)
    INIT_LIST_HEAD(&s->s_dentry_lru);
    INIT_LIST_HEAD(&s->s_inode_lru);
    spin_lock_init(&s->s_inode_lru_lock);
    + INIT_LIST_HEAD(&s->s_mounts);
    init_rwsem(&s->s_umount);
    mutex_init(&s->s_lock);
    lockdep_set_class(&s->s_umount, &type->s_umount_key);
    @@ -200,6 +201,7 @@ static inline void destroy_super(struct super_block *s)
    free_percpu(s->s_files);
    #endif
    security_sb_free(s);
    + WARN_ON(!list_empty(&s->s_mounts));
    kfree(s->s_subtype);
    kfree(s->s_options);
    kfree(s);
    diff --git a/include/linux/fs.h b/include/linux/fs.h
    index ba98668..6eb9a30 100644
    --- a/include/linux/fs.h
    +++ b/include/linux/fs.h
    @@ -1412,6 +1412,7 @@ struct super_block {
    #else
    struct list_head s_files;
    #endif
    + struct list_head s_mounts; /* list of mounts */
    /* s_dentry_lru, s_nr_dentry_unused protected by dcache.c lru locks */
    struct list_head s_dentry_lru; /* unused dentry lru */
    int s_nr_dentry_unused; /* # of dentry on lru */
    diff --git a/include/linux/mount.h b/include/linux/mount.h
    index 33fe53d..f88c726 100644
    --- a/include/linux/mount.h
    +++ b/include/linux/mount.h
    @@ -67,6 +67,7 @@ struct vfsmount {
    #endif
    struct list_head mnt_mounts; /* list of children, anchored here */
    struct list_head mnt_child; /* and going through their mnt_child */
    + struct list_head mnt_instance; /* mount instance on sb->s_mounts */
    int mnt_flags;
    /* 4 bytes hole on 64bits arches without fsnotify */
    #ifdef CONFIG_FSNOTIFY
    --
    1.7.3.4


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