proc: fix NULL ->i_fop oops

[linux-2.6] / fs / nfs / getroot.c

diff --git a/fs/nfs/getroot.c b/fs/nfs/getroot.c
index 8391bd7a83ce46b81b9480f6710e7cbe37512ae3..0ee43843f4ec40c79f1516fb869a5eb720cb355c 100644 (file)
--- a/fs/nfs/getroot.c
+++ b/fs/nfs/getroot.c
@@ -25,7 +25,6 @@
 #include <linux/nfs_mount.h>
 #include <linux/nfs4_mount.h>
 #include <linux/lockd/bind.h>
-#include <linux/smp_lock.h>
 #include <linux/seq_file.h>
 #include <linux/mount.h>
 #include <linux/nfs_idmap.h>
@@ -42,7 +41,25 @@
 #include "internal.h"
 
 #define NFSDBG_FACILITY                NFSDBG_CLIENT
-#define NFS_PARANOIA 1
+
+/*
+ * 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
@@ -56,33 +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;
 
@@ -98,6 +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
@@ -135,17 +129,15 @@ int nfs4_path_walk(struct nfs_server *server,
        struct nfs_fh lastfh;
        struct qstr name;
        int ret;
-       //int referral_count = 0;
 
        dprintk("--> nfs4_path_walk(,,%s)\n", path);
 
        fsinfo.fattr = &fattr;
        nfs_fattr_init(&fattr);
 
-       if (*path++ != '/') {
-               dprintk("nfs4_get_root: Path does not begin with a slash\n");
-               return -EINVAL;
-       }
+       /* Eat leading slashes */
+       while (*path == '/')
+               path++;
 
        /* Start by getting the root filehandle from the server */
        ret = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo);
@@ -160,6 +152,7 @@ int nfs4_path_walk(struct nfs_server *server,
                return -ENOTDIR;
        }
 
+       /* FIXME: It is quite valid for the server to return a referral here */
        if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL) {
                printk(KERN_ERR "nfs4_get_root:"
                       " getroot obtained referral\n");
@@ -178,6 +171,9 @@ next_component:
                path++;
        name.len = path - (const char *) name.name;
 
+       if (name.len > NFS4_MAXNAMLEN)
+               return -ENAMETOOLONG;
+
 eat_dot_dir:
        while (*path == '/')
                path++;
@@ -187,6 +183,7 @@ eat_dot_dir:
                goto eat_dot_dir;
        }
 
+       /* FIXME: Why shouldn't the user be able to use ".." in the path? */
        if (path[0] == '.' && path[1] == '.' && (path[2] == '/' || !path[2])
            ) {
                printk(KERN_ERR "nfs4_get_root:"
@@ -212,6 +209,7 @@ eat_dot_dir:
                return -ENOTDIR;
        }
 
+       /* FIXME: Referrals are quite valid here too */
        if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL) {
                printk(KERN_ERR "nfs4_get_root:"
                       " lookupfh obtained referral\n");
@@ -239,33 +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) {
@@ -287,6 +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