--------------------------------- CUT HERE
-----------------------------
From: Trond Myklebust <[email protected]>
Date: Thu, 25 Oct 2007 13:56:10 -0400
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: Trond Myklebust <[email protected]>
---
fs/nfs/getroot.c | 81 +++++++++++++++++
+------------------------------------
1 files changed, 27 insertions(+), 54 deletions(-)
diff --git a/fs/nfs/getroot.c b/fs/nfs/getroot.c
index 522e5ad..0ee4384 100644
--- a/fs/nfs/getroot.c
+++ b/fs/nfs/getroot.c
@@ -43,6 +43,25 @@
#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
*/
struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh
*mntfh)
@@ -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
