Commit b09b9417 authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFS: Fix the ustat() regression 



Since 2.6.18, the superblock sb->s_root has been a dummy dentry with a
dummy inode. This breaks ustat(), which actually uses sb->s_root in a
vfstat() call.

Fix this by making the s_root a dummy alias to the directory inode that was
used when creating the superblock.

Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent 2ffbb837

fs/nfs/getroot.c

+27 −54
Original line number Diff line number Diff line
@@ -42,6 +42,25 @@ 


#define NFSDBG_FACILITY		NFSDBG_CLIENT



/*

 * Set the superblock root dentry.

 * Note that this function frees the inode in case of error.

 */

static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *inode)

{

	/* The mntroot acts as the dummy root dentry for this superblock */

	if (sb->s_root == NULL) {

		sb->s_root = d_alloc_root(inode);

		if (sb->s_root == NULL) {

			iput(inode);

			return -ENOMEM;

		}

		/* Circumvent igrab(): we know the inode is not being freed */

		atomic_inc(&inode->i_count);

	}

	return 0;

}



/*

 * get an NFS2/NFS3 root dentry from the root filehandle

 */
@@ -54,33 +73,6 @@ struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh) 
	struct inode *inode;

	int error;



	/* create a dummy root dentry with dummy inode for this superblock */

	if (!sb->s_root) {

		struct nfs_fh dummyfh;

		struct dentry *root;

		struct inode *iroot;



		memset(&dummyfh, 0, sizeof(dummyfh));

		memset(&fattr, 0, sizeof(fattr));

		nfs_fattr_init(&fattr);

		fattr.valid = NFS_ATTR_FATTR;

		fattr.type = NFDIR;

		fattr.mode = S_IFDIR | S_IRUSR | S_IWUSR;

		fattr.nlink = 2;



		iroot = nfs_fhget(sb, &dummyfh, &fattr);

		if (IS_ERR(iroot))

			return ERR_PTR(PTR_ERR(iroot));



		root = d_alloc_root(iroot);

		if (!root) {

			iput(iroot);

			return ERR_PTR(-ENOMEM);

		}



		sb->s_root = root;

	}



	/* get the actual root for this mount */

	fsinfo.fattr = &fattr;
@@ -96,6 +88,10 @@ struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh) 
		return ERR_PTR(PTR_ERR(inode));

	}



	error = nfs_superblock_set_dummy_root(sb, inode);

	if (error != 0)

		return ERR_PTR(error);



	/* root dentries normally start off anonymous and get spliced in later

	 * if the dentry tree reaches them; however if the dentry already

	 * exists, we'll pick it up at this point and use it as the root
@@ -241,33 +237,6 @@ struct dentry *nfs4_get_root(struct super_block *sb, struct nfs_fh *mntfh) 


	dprintk("--> nfs4_get_root()\n");



	/* create a dummy root dentry with dummy inode for this superblock */

	if (!sb->s_root) {

		struct nfs_fh dummyfh;

		struct dentry *root;

		struct inode *iroot;



		memset(&dummyfh, 0, sizeof(dummyfh));

		memset(&fattr, 0, sizeof(fattr));

		nfs_fattr_init(&fattr);

		fattr.valid = NFS_ATTR_FATTR;

		fattr.type = NFDIR;

		fattr.mode = S_IFDIR | S_IRUSR | S_IWUSR;

		fattr.nlink = 2;



		iroot = nfs_fhget(sb, &dummyfh, &fattr);

		if (IS_ERR(iroot))

			return ERR_PTR(PTR_ERR(iroot));



		root = d_alloc_root(iroot);

		if (!root) {

			iput(iroot);

			return ERR_PTR(-ENOMEM);

		}



		sb->s_root = root;

	}



	/* get the info about the server and filesystem */

	error = nfs4_server_capabilities(server, mntfh);

	if (error < 0) {
@@ -289,6 +258,10 @@ struct dentry *nfs4_get_root(struct super_block *sb, struct nfs_fh *mntfh) 
		return ERR_PTR(PTR_ERR(inode));

	}



	error = nfs_superblock_set_dummy_root(sb, inode);

	if (error != 0)

		return ERR_PTR(error);



	/* root dentries normally start off anonymous and get spliced in later

	 * if the dentry tree reaches them; however if the dentry already

	 * exists, we'll pick it up at this point and use it as the root