[PATCH 3/6] NFS: Use d_automount() rather than abusing follow_link()

David Howells
2010-07-22T17:59:31Z

Make NFS use the new d_automount() dentry operation rather than abusing
follow_link() on directories.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
---

fs/nfs/dir.c | 4 ++
fs/nfs/inode.c | 4 +-
fs/nfs/internal.h | 1 +
fs/nfs/namespace.c | 87 ++++++++++++++++++++++--------------------------
include/linux/nfs_fs.h | 1 -
5 files changed, 46 insertions(+), 51 deletions(-)

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index e60416d..9ce04af 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -727,7 +727,7 @@ int nfs_lookup_verify_inode(struct inode *inode, struct nameidata *nd)
{
struct nfs_server *server = NFS_SERVER(inode);

- if (test_bit(NFS_INO_MOUNTPOINT, &NFS_I(inode)->flags))
+ if (IS_AUTOMOUNT(inode))
return 0;
if (nd != NULL) {
/* VFS wants an on-the-wire revalidation */
@@ -927,6 +927,7 @@ const struct dentry_operations nfs_dentry_operations = {
.d_revalidate = nfs_lookup_revalidate,
.d_delete = nfs_dentry_delete,
.d_iput = nfs_dentry_iput,
+ .d_automount = nfs_d_automount,
};

static struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd)
@@ -1002,6 +1003,7 @@ const struct dentry_operations nfs4_dentry_operations = {
.d_revalidate = nfs_open_revalidate,
.d_delete = nfs_dentry_delete,
.d_iput = nfs_dentry_iput,
+ .d_automount = nfs_d_automount,
};

/*
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 099b351..848abe8 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -295,7 +295,7 @@ nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr)
else
inode->i_op = &nfs_mountpoint_inode_operations;
inode->i_fop = NULL;
- set_bit(NFS_INO_MOUNTPOINT, &nfsi->flags);
+ inode->i_flags |= S_AUTOMOUNT;
}
} else if (S_ISLNK(inode->i_mode))
inode->i_op = &nfs_symlink_inode_operations;
@@ -1138,7 +1138,7 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
/* Update the fsid? */
if (S_ISDIR(inode->i_mode) && (fattr->valid & NFS_ATTR_FATTR_FSID) &&
!nfs_fsid_equal(&server->fsid, &fattr->fsid) &&
- !test_bit(NFS_INO_MOUNTPOINT, &nfsi->flags))
+ !IS_AUTOMOUNT(inode))
server->fsid = fattr->fsid;

/*
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index e70f44b..f597aac 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -239,6 +239,7 @@ extern char *nfs_path(const char *base,
const struct dentry *droot,
const struct dentry *dentry,
char *buffer, ssize_t buflen);
+extern struct vfsmount *nfs_d_automount(struct path *path);

/* getroot.c */
extern struct dentry *nfs_get_root(struct super_block *, struct nfs_fh *);
diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c
index db6aa36..bf80079 100644
--- a/fs/nfs/namespace.c
+++ b/fs/nfs/namespace.c
@@ -88,9 +88,8 @@ Elong:
}

/*
- * nfs_follow_mountpoint - handle crossing a mountpoint on the server
- * @dentry - dentry of mountpoint
- * @nd - nameidata info
+ * nfs_d_automount - Handle crossing a mountpoint on the server
+ * @path - The mountpoint
*
* When we encounter a mountpoint on the server, we want to set up
* a mountpoint on the client too, to prevent inode numbers from
@@ -100,87 +99,81 @@ Elong:
* situation, and that different filesystems may want to use
* different security flavours.
*/
-static void * nfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
+struct vfsmount *nfs_d_automount(struct path *path)
{
struct vfsmount *mnt;
- struct nfs_server *server = NFS_SERVER(dentry->d_inode);
+ struct nfs_server *server = NFS_SERVER(path->dentry->d_inode);
struct dentry *parent;
struct nfs_fh *fh = NULL;
struct nfs_fattr *fattr = NULL;
int err;

- dprintk("--> nfs_follow_mountpoint()\n");
+ dprintk("--> nfs_d_automount()\n");

- err = -ESTALE;
- if (IS_ROOT(dentry))
- goto out_err;
+ mnt = ERR_PTR(-ESTALE);
+ if (IS_ROOT(path->dentry))
+ goto out_nofree;

- err = -ENOMEM;
+ mnt = ERR_PTR(-ENOMEM);
fh = nfs_alloc_fhandle();
fattr = nfs_alloc_fattr();
if (fh == NULL || fattr == NULL)
- goto out_err;
+ goto out;

dprintk("%s: enter\n", __func__);
- dput(nd->path.dentry);
- nd->path.dentry = dget(dentry);

- /* Look it up again */
- parent = dget_parent(nd->path.dentry);
+ /* Look it up again to get its attributes */
+ parent = dget_parent(path->dentry);
err = server->nfs_client->rpc_ops->lookup(parent->d_inode,
- &nd->path.dentry->d_name,
+ &path->dentry->d_name,
fh, fattr);
dput(parent);
- if (err != 0)
- goto out_err;
+ if (err != 0) {
+ mnt = ERR_PTR(err);
+ goto out;
+ }

if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)
- mnt = nfs_do_refmount(nd->path.mnt, nd->path.dentry);
+ mnt = nfs_do_refmount(path->mnt, path->dentry);
else
- mnt = nfs_do_submount(nd->path.mnt, nd->path.dentry, fh,
- fattr);
- err = PTR_ERR(mnt);
+ mnt = nfs_do_submount(path->mnt, path->dentry, fh, fattr);
if (IS_ERR(mnt))
- goto out_err;
+ goto out;

mntget(mnt);
- err = do_add_mount(mnt, &nd->path, nd->path.mnt->mnt_flags|MNT_SHRINKABLE,
+ err = do_add_mount(mnt, path, path->mnt->mnt_flags | MNT_SHRINKABLE,
&nfs_automount_list);
- if (err < 0) {
+ 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);
- if (err == -EBUSY)
- goto out_follow;
- goto out_err;
+ 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;
}
- path_put(&nd->path);
- nd->path.mnt = mnt;
- nd->path.dentry = dget(mnt->mnt_root);
- schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
+
out:
nfs_free_fattr(fattr);
nfs_free_fhandle(fh);
- dprintk("%s: done, returned %d\n", __func__, err);
-
- dprintk("<-- nfs_follow_mountpoint() = %d\n", err);
- return ERR_PTR(err);
-out_err:
- path_put(&nd->path);
- goto out;
-out_follow:
- while (d_mountpoint(nd->path.dentry) &&
- follow_down(&nd->path))
- ;
- err = 0;
- goto out;
+out_nofree:
+ dprintk("<-- nfs_follow_mountpoint() = %p\n", mnt);
+ return mnt;
}

const struct inode_operations nfs_mountpoint_inode_operations = {
- .follow_link = nfs_follow_mountpoint,
.getattr = nfs_getattr,
};

const struct inode_operations nfs_referral_inode_operations = {
- .follow_link = nfs_follow_mountpoint,
};

static void nfs_expire_automounts(struct work_struct *work)
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 77c2ae5..4511220 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -205,7 +205,6 @@ struct nfs_inode {
#define NFS_INO_ADVISE_RDPLUS (0) /* advise readdirplus */
#define NFS_INO_STALE (1) /* possible stale inode */
#define NFS_INO_ACL_LRU_SET (2) /* Inode is on the LRU list */
-#define NFS_INO_MOUNTPOINT (3) /* inode is remote mountpoint */
#define NFS_INO_FLUSHING (4) /* inode is flushing out data */
#define NFS_INO_FSCACHE (5) /* inode can be cached by FS-Cache */
#define NFS_INO_FSCACHE_LOCK (6) /* FS-Cache cookie management lock */