Unionfs: lower nameidata support for nfsv4

Pass nameidata structures as needed to the lower file system, support
LOOKUP_ACCESS/OPEN intents.  This makes unionfs work on top of nfsv4.

Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>

diff --git a/fs/unionfs/dentry.c b/fs/unionfs/dentry.c
index b21f1e37218f4c1a2428efbedf79daa88eb46507..52bcb1858666137fbb2d587ede1693acdc40a7c6 100644 (file)
--- a/fs/unionfs/dentry.c
+++ b/fs/unionfs/dentry.c
@@ -156,8 +156,15 @@ static bool __unionfs_d_revalidate_one(struct dentry *dentry,
                if (!lower_dentry || !lower_dentry->d_op
                    || !lower_dentry->d_op->d_revalidate)
                        continue;
-               if (!lower_dentry->d_op->d_revalidate(lower_dentry,
-                                                     &lowernd))
+               /*
+                * Don't pass nameidata to lower file system, because we
+                * don't want an arbitrary lower file being opened or
+                * returned to us: it may be useless to us because of the
+                * fanout nature of unionfs (cf. file/directory open-file
+                * invariants).  We will open lower files as and when needed
+                * later on.
+                */
+               if (!lower_dentry->d_op->d_revalidate(lower_dentry, NULL))
                        valid = false;
        }
 

diff --git a/fs/unionfs/inode.c b/fs/unionfs/inode.c
index f8b2c88ccd234255db4492914b6bd6e215a9e455..7ee4760365cb529927f04590926e068917839a70 100644 (file)
--- a/fs/unionfs/inode.c
+++ b/fs/unionfs/inode.c
@@ -27,6 +27,7 @@ static int unionfs_create(struct inode *parent, struct dentry *dentry,
        struct dentry *lower_parent_dentry = NULL;
        char *name = NULL;
        int valid = 0;
+       struct nameidata lower_nd;
 
        unionfs_read_lock(dentry->d_sb);
        unionfs_lock_dentry(dentry);
@@ -113,7 +114,12 @@ static int unionfs_create(struct inode *parent, struct dentry *dentry,
                goto out;
        }
 
-       err = vfs_create(lower_parent_dentry->d_inode, lower_dentry, mode, nd);
+       err = init_lower_nd(&lower_nd, LOOKUP_CREATE);
+       if (err < 0)
+               goto out;
+       err = vfs_create(lower_parent_dentry->d_inode, lower_dentry, mode,
+                        &lower_nd);
+       release_lower_nd(&lower_nd, err);
 
        if (!err) {
                err = PTR_ERR(unionfs_interpose(dentry, parent->i_sb, 0));

diff --git a/fs/unionfs/lookup.c b/fs/unionfs/lookup.c
index 963d62225cd3c8e21467299db70dbcfdd255be73..21097147505e6670d8fc71c275a4d7cafbd5e3a2 100644 (file)
--- a/fs/unionfs/lookup.c
+++ b/fs/unionfs/lookup.c
@@ -583,6 +583,11 @@ void update_bstart(struct dentry *dentry)
  * Inside that nd structure, this function may also return an allocated
  * struct file (for open intents).  The caller, when done with this nd, must
  * kfree the intent file (using release_lower_nd).
+ *
+ * XXX: this code, and the callers of this code, should be redone using
+ * vfs_path_lookup() when (1) the nameidata structure is refactored into a
+ * separate intent-structure, and (2) open_namei() is broken into a VFS-only
+ * function and a method that other file systems can call.
  */
 int init_lower_nd(struct nameidata *nd, unsigned int flags)
 {
@@ -597,11 +602,16 @@ int init_lower_nd(struct nameidata *nd, unsigned int flags)
 #endif /* ALLOC_LOWER_ND_FILE */
 
        memset(nd, 0, sizeof(struct nameidata));
+       if (!flags)
+               return err;
 
        switch (flags) {
        case LOOKUP_CREATE:
-               nd->flags = LOOKUP_CREATE;
-               nd->intent.open.flags = FMODE_READ | FMODE_WRITE | O_CREAT;
+               nd->intent.open.flags |= O_CREAT;
+               /* fall through: shared code for create/open cases */
+       case LOOKUP_OPEN:
+               nd->flags = flags;
+               nd->intent.open.flags |= (FMODE_READ | FMODE_WRITE);
 #ifdef ALLOC_LOWER_ND_FILE
                file = kzalloc(sizeof(struct file), GFP_KERNEL);
                if (!file) {
@@ -611,11 +621,15 @@ int init_lower_nd(struct nameidata *nd, unsigned int flags)
                nd->intent.open.file = file;
 #endif /* ALLOC_LOWER_ND_FILE */
                break;
+       case LOOKUP_ACCESS:
+               nd->flags = flags;
+               break;
        default:
                /*
                 * We should never get here, for now.
                 * We can add new cases here later on.
                 */
+               dprintk("unionfs: unknown nameidata flag 0x%x\n", flags);
                BUG();
                break;
        }
@@ -627,7 +641,7 @@ void release_lower_nd(struct nameidata *nd, int err)
 {
        if (!nd->intent.open.file)
                return;
-       if (!err)
+       else if (!err)
                release_open_intent(nd);
 #ifdef ALLOC_LOWER_ND_FILE
        kfree(nd->intent.open.file);