dynamic_dname() helper function is provided to take care of this.
d_automount: called when an automount dentry is to be traversed (optional).
- This should create a new VFS mount record, mount it on the directory
- and return the record to the caller. The caller is supplied with a
- path parameter giving the automount directory to describe the automount
- target and the parent VFS mount record to provide inheritable mount
- parameters. NULL should be returned if someone else managed to make
- the automount first. If the automount failed, then an error code
- should be returned. If -EISDIR is returned, then the directory will
- be treated as an ordinary directory and returned to pathwalk to
- continue walking.
+ This should create a new VFS mount record and return the record to the
+ caller. The caller is supplied with a path parameter giving the
+ automount directory to describe the automount target and the parent
+ VFS mount record to provide inheritable mount parameters. NULL should
+ be returned if someone else managed to make the automount first. If
+ the vfsmount creation failed, then an error code should be returned.
+ If -EISDIR is returned, then the directory will be treated as an
+ ordinary directory and returned to pathwalk to continue walking.
+
+ If a vfsmount is returned, the caller will attempt to mount it on the
+ mountpoint and will remove the vfsmount from its expiration list in
+ the case of failure. The vfsmount should be returned with 2 refs on
+ it to prevent automatic expiration - the caller will clean up the
+ additional ref.
This function is only used if DCACHE_NEED_AUTOMOUNT is set on the
dentry. This is set by __d_instantiate() if S_AUTOMOUNT is set on the
struct vfsmount *afs_d_automount(struct path *path)
{
struct vfsmount *newmnt;
- int err;
_enter("{%s,%s}", path->mnt->mnt_devname, path->dentry->d_name.name);
if (IS_ERR(newmnt))
return newmnt;
- mntget(newmnt);
- err = do_add_mount(newmnt, path, MNT_SHRINKABLE, &afs_vfsmounts);
- switch (err) {
- case 0:
- queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
- afs_mntpt_expiry_timeout * HZ);
- _leave(" = %p {%s}", newmnt, newmnt->mnt_devname);
- return newmnt;
- case -EBUSY:
- /* someone else made a mount here whilst we were busy */
- mntput(newmnt);
- _leave(" = NULL [EBUSY]");
- return NULL;
- default:
- mntput(newmnt);
- _leave(" = %d", err);
- return ERR_PTR(err);
- }
+ mntget(newmnt); /* prevent immediate expiration */
+ mnt_set_expiry(newmnt, &afs_vfsmounts);
+ queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
+ afs_mntpt_expiry_timeout * HZ);
+ _leave(" = %p {%s}", newmnt, newmnt->mnt_devname);
+ return newmnt;
}
/*
struct vfsmount *cifs_dfs_d_automount(struct path *path)
{
struct vfsmount *newmnt;
- int err;
cFYI(1, "in %s", __func__);
return newmnt;
}
- mntget(newmnt);
- err = do_add_mount(newmnt, path, path->mnt->mnt_flags | MNT_SHRINKABLE,
- &cifs_dfs_automount_list);
- switch (err) {
- case 0:
- schedule_delayed_work(&cifs_dfs_automount_task,
- cifs_dfs_mountpoint_expiry_timeout);
- cFYI(1, "leaving %s [ok]" , __func__);
- return newmnt;
- case -EBUSY:
- /* someone else made a mount here whilst we were busy */
- mntput(newmnt);
- cFYI(1, "leaving %s [EBUSY]" , __func__);
- return NULL;
- default:
- mntput(newmnt);
- cFYI(1, "leaving %s [error %d]" , __func__, err);
- return ERR_PTR(err);
- }
+ mntget(newmnt); /* prevent immediate expiration */
+ mnt_set_expiry(newmnt, &cifs_dfs_automount_list);
+ schedule_delayed_work(&cifs_dfs_automount_task,
+ cifs_dfs_mountpoint_expiry_timeout);
+ cFYI(1, "leaving %s [ok]" , __func__);
+ return newmnt;
}
const struct inode_operations cifs_dfs_referral_inode_operations = {
extern void release_mounts(struct list_head *);
extern void umount_tree(struct vfsmount *, int, struct list_head *);
extern struct vfsmount *copy_tree(struct vfsmount *, struct dentry *, int);
+extern int do_add_mount(struct vfsmount *, struct path *, int);
+extern void mnt_clear_expiry(struct vfsmount *);
extern void __init mnt_init(void);
bool *need_mntput)
{
struct vfsmount *mnt;
+ int err;
if (!path->dentry->d_op || !path->dentry->d_op->d_automount)
return -EREMOTE;
return -EREMOTE;
return PTR_ERR(mnt);
}
+
if (!mnt) /* mount collision */
return 0;
+ /* The new mount record should have at least 2 refs to prevent it being
+ * expired before we get a chance to add it
+ */
+ BUG_ON(mnt_get_count(mnt) < 2);
+
if (mnt->mnt_sb == path->mnt->mnt_sb &&
mnt->mnt_root == path->dentry) {
+ mnt_clear_expiry(mnt);
+ mntput(mnt);
mntput(mnt);
return -ELOOP;
}
- dput(path->dentry);
- if (*need_mntput)
- mntput(path->mnt);
- path->mnt = mnt;
- path->dentry = dget(mnt->mnt_root);
- *need_mntput = true;
- return 0;
+ /* We need to add the mountpoint to the parent. The filesystem may
+ * have placed it on an expiry list, and so we need to make sure it
+ * won't be expired under us if do_add_mount() fails (do_add_mount()
+ * will eat a reference unconditionally).
+ */
+ mntget(mnt);
+ err = do_add_mount(mnt, path, path->mnt->mnt_flags | MNT_SHRINKABLE);
+ switch (err) {
+ case -EBUSY:
+ /* Someone else made a mount here whilst we were busy */
+ err = 0;
+ default:
+ mnt_clear_expiry(mnt);
+ mntput(mnt);
+ mntput(mnt);
+ return err;
+ case 0:
+ mntput(mnt);
+ dput(path->dentry);
+ if (*need_mntput)
+ mntput(path->mnt);
+ path->mnt = mnt;
+ path->dentry = dget(mnt->mnt_root);
+ *need_mntput = true;
+ return 0;
+ }
}
/*
if (IS_ERR(mnt))
return PTR_ERR(mnt);
- return do_add_mount(mnt, path, mnt_flags, NULL);
+ return do_add_mount(mnt, path, mnt_flags);
}
/*
* add a mount into a namespace's mount tree
- * - provide the option of adding the new mount to an expiration list
+ * - this unconditionally eats one of the caller's references to newmnt.
*/
-int do_add_mount(struct vfsmount *newmnt, struct path *path,
- int mnt_flags, struct list_head *fslist)
+int do_add_mount(struct vfsmount *newmnt, struct path *path, int mnt_flags)
{
int err;
if ((err = graft_tree(newmnt, path)))
goto unlock;
- if (fslist) /* add to the specified expiration list */
- list_add_tail(&newmnt->mnt_expire, fslist);
-
up_write(&namespace_sem);
return 0;
return err;
}
-EXPORT_SYMBOL_GPL(do_add_mount);
+/**
+ * mnt_set_expiry - Put a mount on an expiration list
+ * @mnt: The mount to list.
+ * @expiry_list: The list to add the mount to.
+ */
+void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list)
+{
+ down_write(&namespace_sem);
+ br_write_lock(vfsmount_lock);
+
+ list_add_tail(&mnt->mnt_expire, expiry_list);
+
+ br_write_unlock(vfsmount_lock);
+ up_write(&namespace_sem);
+}
+EXPORT_SYMBOL(mnt_set_expiry);
+
+/*
+ * Remove a vfsmount from any expiration list it may be on
+ */
+void mnt_clear_expiry(struct vfsmount *mnt)
+{
+ if (!list_empty(&mnt->mnt_expire)) {
+ down_write(&namespace_sem);
+ br_write_lock(vfsmount_lock);
+ list_del_init(&mnt->mnt_expire);
+ br_write_unlock(vfsmount_lock);
+ up_write(&namespace_sem);
+ }
+}
/*
* process a list of expirable mountpoints with the intent of discarding any
if (IS_ERR(mnt))
goto out;
- mntget(mnt);
- err = do_add_mount(mnt, path, path->mnt->mnt_flags | MNT_SHRINKABLE,
- &nfs_automount_list);
- switch (err) {
- case 0:
- dprintk("%s: done, success\n", __func__);
- schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
- break;
- case -EBUSY:
- /* someone else made a mount here whilst we were busy */
- mntput(mnt);
- dprintk("%s: done, collision\n", __func__);
- mnt = NULL;
- break;
- default:
- mntput(mnt);
- dprintk("%s: done, error %d\n", __func__, err);
- mnt = ERR_PTR(err);
- break;
- }
+ dprintk("%s: done, success\n", __func__);
+ mntget(mnt); /* prevent immediate expiration */
+ mnt_set_expiry(mnt, &nfs_automount_list);
+ schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
out:
nfs_free_fattr(fattr);
int flags, const char *name,
void *data);
-struct nameidata;
-
-struct path;
-extern int do_add_mount(struct vfsmount *newmnt, struct path *path,
- int mnt_flags, struct list_head *fslist);
-
+extern void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list);
extern void mark_mounts_for_expiry(struct list_head *mounts);
extern dev_t name_to_dev_t(char *name);
projects / mv-sheeva.git / commitdiff