From: Miklos Szeredi <mszeredi@xxxxxxx>
Keep track of vfsmounts belonging to a superblock. List is protected
by vfsmount_lock.
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
---
fs/namespace.c | 10 ++++++++--
fs/super.c | 7 +++++++
include/linux/fs.h | 1 +
include/linux/mount.h | 1 +
4 files changed, 17 insertions(+), 2 deletions(-)
Index: linux-2.6/include/linux/fs.h
===================================================================
--- linux-2.6.orig/include/linux/fs.h 2011-01-12 15:47:09.000000000 +0100
+++ linux-2.6/include/linux/fs.h 2011-01-12 15:47:12.000000000 +0100
@@ -1384,6 +1384,7 @@ 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 */
Index: linux-2.6/include/linux/mount.h
===================================================================
--- linux-2.6.orig/include/linux/mount.h 2011-01-12 15:47:09.000000000 +0100
+++ linux-2.6/include/linux/mount.h 2011-01-12 15:47:12.000000000 +0100
@@ -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
Index: linux-2.6/fs/namespace.c
===================================================================
--- linux-2.6.orig/fs/namespace.c 2011-01-12 15:47:09.000000000 +0100
+++ linux-2.6/fs/namespace.c 2011-01-12 15:47:12.000000000 +0100
@@ -705,6 +705,10 @@ static struct vfsmount *clone_mnt(struct
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;
@@ -714,9 +718,13 @@ static struct vfsmount *clone_mnt(struct
}
static inline void mntfree(struct vfsmount *mnt)
+__releases(vfsmount_lock)
{
struct super_block *sb = mnt->mnt_sb;
+ list_del(&mnt->mnt_instance);
+ br_write_unlock(vfsmount_lock);
+
/*
* This probably indicates that somebody messed
* up a mnt_want/drop_write() pair. If this
@@ -768,7 +776,6 @@ static inline void __mntput(struct vfsmo
acct_auto_close_mnt(mnt);
goto put_again;
}
- br_write_unlock(vfsmount_lock);
mntfree(mnt);
}
#else
@@ -786,7 +793,6 @@ static inline void __mntput(struct vfsmo
acct_auto_close_mnt(mnt);
goto put_again;
}
- br_write_unlock(vfsmount_lock);
mntfree(mnt);
}
#endif
Index: linux-2.6/fs/super.c
===================================================================
--- linux-2.6.orig/fs/super.c 2011-01-12 15:47:10.000000000 +0100
+++ linux-2.6/fs/super.c 2011-01-12 15:47:12.000000000 +0100
@@ -75,6 +75,7 @@ static struct super_block *alloc_super(s
INIT_HLIST_BL_HEAD(&s->s_anon);
INIT_LIST_HEAD(&s->s_inodes);
INIT_LIST_HEAD(&s->s_dentry_lru);
+ 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);
@@ -128,6 +129,7 @@ static inline void destroy_super(struct
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);
@@ -1018,6 +1020,11 @@ vfs_kern_mount(struct file_system_type *
mnt->mnt_parent = mnt;
up_write(&mnt->mnt_sb->s_umount);
free_secdata(secdata);
+
+ br_write_lock(vfsmount_lock);
+ list_add_tail(&mnt->mnt_instance, &mnt->mnt_sb->s_mounts);
+ br_write_unlock(vfsmount_lock);
+
return mnt;
out_sb:
dput(mnt->mnt_root);
--
--
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