NFS: Fix double d_drop in nfs_instantiate() error path

If the LOOKUP or GETATTR in nfs_instantiate fail, nfs_instantiate will do a
d_drop before returning.  But some callers already do a d_drop in the case
of an error return.  Make certain we do only one d_drop in all error paths.

This issue was introduced because over time, the symlink proc API diverged
slightly from the create/mkdir/mknod proc API.  To prevent other coding
mistakes of this type, change the symlink proc API to be more like
create/mkdir/mknod and move the nfs_instantiate call into the symlink proc
routines so it is used in exactly the same way for create, mkdir, mknod,
and symlink.

Test plan:
Connectathon, all versions of NFS.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 084e8cb..affd3ae 100644 (file)
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1147,23 +1147,20 @@ int nfs_instantiate(struct dentry *dentry, struct nfs_fh *fhandle,
                struct inode *dir = dentry->d_parent->d_inode;
                error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, fhandle, fattr);
                if (error)
-                       goto out_err;
+                       return error;
        }
        if (!(fattr->valid & NFS_ATTR_FATTR)) {
                struct nfs_server *server = NFS_SB(dentry->d_sb);
                error = server->nfs_client->rpc_ops->getattr(server, fhandle, fattr);
                if (error < 0)
-                       goto out_err;
+                       return error;
        }
        inode = nfs_fhget(dentry->d_sb, fhandle, fattr);
        error = PTR_ERR(inode);
        if (IS_ERR(inode))
-               goto out_err;
+               return error;
        d_instantiate(dentry, inode);
        return 0;
-out_err:
-       d_drop(dentry);
-       return error;
 }
 
 /*
@@ -1448,8 +1445,6 @@ static int
 nfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
 {
        struct iattr attr;
-       struct nfs_fattr sym_attr;
-       struct nfs_fh sym_fh;
        struct qstr qsymname;
        int error;
 
@@ -1473,12 +1468,9 @@ dentry->d_parent->d_name.name, dentry->d_name.name);
 
        lock_kernel();
        nfs_begin_data_update(dir);
-       error = NFS_PROTO(dir)->symlink(dir, &dentry->d_name, &qsymname,
-                                         &attr, &sym_fh, &sym_attr);
+       error = NFS_PROTO(dir)->symlink(dir, dentry, &qsymname, &attr);
        nfs_end_data_update(dir);
        if (!error)
-               error = nfs_instantiate(dentry, &sym_fh, &sym_attr);
-       else
                d_drop(dentry);
        unlock_kernel();
        return error;

diff --git a/fs/nfs/nfs3proc.c b/fs/nfs/nfs3proc.c
index 9e8258e..d85ac42 100644 (file)
--- a/fs/nfs/nfs3proc.c
+++ b/fs/nfs/nfs3proc.c
@@ -544,23 +544,23 @@ nfs3_proc_link(struct inode *inode, struct inode *dir, struct qstr *name)
 }
 
 static int
-nfs3_proc_symlink(struct inode *dir, struct qstr *name, struct qstr *path,
-                 struct iattr *sattr, struct nfs_fh *fhandle,
-                 struct nfs_fattr *fattr)
+nfs3_proc_symlink(struct inode *dir, struct dentry *dentry, struct qstr *path,
+                 struct iattr *sattr)
 {
-       struct nfs_fattr        dir_attr;
+       struct nfs_fh fhandle;
+       struct nfs_fattr fattr, dir_attr;
        struct nfs3_symlinkargs arg = {
                .fromfh         = NFS_FH(dir),
-               .fromname       = name->name,
-               .fromlen        = name->len,
+               .fromname       = dentry->d_name.name,
+               .fromlen        = dentry->d_name.len,
                .topath         = path->name,
                .tolen          = path->len,
                .sattr          = sattr
        };
        struct nfs3_diropres    res = {
                .dir_attr       = &dir_attr,
-               .fh             = fhandle,
-               .fattr          = fattr
+               .fh             = &fhandle,
+               .fattr          = &fattr
        };
        struct rpc_message msg = {
                .rpc_proc       = &nfs3_procedures[NFS3PROC_SYMLINK],
@@ -571,11 +571,17 @@ nfs3_proc_symlink(struct inode *dir, struct qstr *name, struct qstr *path,
 
        if (path->len > NFS3_MAXPATHLEN)
                return -ENAMETOOLONG;
-       dprintk("NFS call  symlink %s -> %s\n", name->name, path->name);
+
+       dprintk("NFS call  symlink %s -> %s\n", dentry->d_name.name,
+                       path->name);
        nfs_fattr_init(&dir_attr);
-       nfs_fattr_init(fattr);
+       nfs_fattr_init(&fattr);
        status = rpc_call_sync(NFS_CLIENT(dir), &msg, 0);
        nfs_post_op_update_inode(dir, &dir_attr);
+       if (status != 0)
+               goto out;
+       status = nfs_instantiate(dentry, &fhandle, &fattr);
+out:
        dprintk("NFS reply symlink: %d\n", status);
        return status;
 }

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index a825547..2d18eac 100644 (file)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2084,24 +2084,24 @@ static int nfs4_proc_link(struct inode *inode, struct inode *dir, struct qstr *n
        return err;
 }
 
-static int _nfs4_proc_symlink(struct inode *dir, struct qstr *name,
-               struct qstr *path, struct iattr *sattr, struct nfs_fh *fhandle,
-               struct nfs_fattr *fattr)
+static int _nfs4_proc_symlink(struct inode *dir, struct dentry *dentry,
+               struct qstr *path, struct iattr *sattr)
 {
        struct nfs_server *server = NFS_SERVER(dir);
-       struct nfs_fattr dir_fattr;
+       struct nfs_fh fhandle;
+       struct nfs_fattr fattr, dir_fattr;
        struct nfs4_create_arg arg = {
                .dir_fh = NFS_FH(dir),
                .server = server,
-               .name = name,
+               .name = &dentry->d_name,
                .attrs = sattr,
                .ftype = NF4LNK,
                .bitmask = server->attr_bitmask,
        };
        struct nfs4_create_res res = {
                .server = server,
-               .fh = fhandle,
-               .fattr = fattr,
+               .fh = &fhandle,
+               .fattr = &fattr,
                .dir_fattr = &dir_fattr,
        };
        struct rpc_message msg = {
@@ -2113,27 +2113,28 @@ static int _nfs4_proc_symlink(struct inode *dir, struct qstr *name,
 
        if (path->len > NFS4_MAXPATHLEN)
                return -ENAMETOOLONG;
+
        arg.u.symlink = path;
-       nfs_fattr_init(fattr);
+       nfs_fattr_init(&fattr);
        nfs_fattr_init(&dir_fattr);
        
        status = rpc_call_sync(NFS_CLIENT(dir), &msg, 0);
-       if (!status)
+       if (!status) {
                update_changeattr(dir, &res.dir_cinfo);
-       nfs_post_op_update_inode(dir, res.dir_fattr);
+               nfs_post_op_update_inode(dir, res.dir_fattr);
+               status = nfs_instantiate(dentry, &fhandle, &fattr);
+       }
        return status;
 }
 
-static int nfs4_proc_symlink(struct inode *dir, struct qstr *name,
-               struct qstr *path, struct iattr *sattr, struct nfs_fh *fhandle,
-               struct nfs_fattr *fattr)
+static int nfs4_proc_symlink(struct inode *dir, struct dentry *dentry,
+               struct qstr *path, struct iattr *sattr)
 {
        struct nfs4_exception exception = { };
        int err;
        do {
                err = nfs4_handle_exception(NFS_SERVER(dir),
-                               _nfs4_proc_symlink(dir, name, path, sattr,
-                                       fhandle, fattr),
+                               _nfs4_proc_symlink(dir, dentry, path, sattr),
                                &exception);
        } while (exception.retry);
        return err;

diff --git a/fs/nfs/proc.c b/fs/nfs/proc.c
index 5a8b940..0b507bf 100644 (file)
--- a/fs/nfs/proc.c
+++ b/fs/nfs/proc.c
@@ -425,14 +425,15 @@ nfs_proc_link(struct inode *inode, struct inode *dir, struct qstr *name)
 }
 
 static int
-nfs_proc_symlink(struct inode *dir, struct qstr *name, struct qstr *path,
-                struct iattr *sattr, struct nfs_fh *fhandle,
-                struct nfs_fattr *fattr)
+nfs_proc_symlink(struct inode *dir, struct dentry *dentry, struct qstr *path,
+                struct iattr *sattr)
 {
+       struct nfs_fh fhandle;
+       struct nfs_fattr fattr;
        struct nfs_symlinkargs  arg = {
                .fromfh         = NFS_FH(dir),
-               .fromname       = name->name,
-               .fromlen        = name->len,
+               .fromname       = dentry->d_name.name,
+               .fromlen        = dentry->d_name.len,
                .topath         = path->name,
                .tolen          = path->len,
                .sattr          = sattr
@@ -445,11 +446,23 @@ nfs_proc_symlink(struct inode *dir, struct qstr *name, struct qstr *path,
 
        if (path->len > NFS2_MAXPATHLEN)
                return -ENAMETOOLONG;
-       dprintk("NFS call  symlink %s -> %s\n", name->name, path->name);
-       nfs_fattr_init(fattr);
-       fhandle->size = 0;
+
+       dprintk("NFS call  symlink %s -> %s\n", dentry->d_name.name,
+                       path->name);
        status = rpc_call_sync(NFS_CLIENT(dir), &msg, 0);
        nfs_mark_for_revalidate(dir);
+
+       /*
+        * V2 SYMLINK requests don't return any attributes.  Setting the
+        * filehandle size to zero indicates to nfs_instantiate that it
+        * should fill in the data with a LOOKUP call on the wire.
+        */
+       if (status == 0) {
+               nfs_fattr_init(&fattr);
+               fhandle.size = 0;
+               status = nfs_instantiate(dentry, &fhandle, &fattr);
+       }
+
        dprintk("NFS reply symlink: %d\n", status);
        return status;
 }

diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 0f33e62..ddf5d75 100644 (file)
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -793,9 +793,8 @@ struct nfs_rpc_ops {
        int     (*rename)  (struct inode *, struct qstr *,
                            struct inode *, struct qstr *);
        int     (*link)    (struct inode *, struct inode *, struct qstr *);
-       int     (*symlink) (struct inode *, struct qstr *, struct qstr *,
-                           struct iattr *, struct nfs_fh *,
-                           struct nfs_fattr *);
+       int     (*symlink) (struct inode *, struct dentry *, struct qstr *,
+                           struct iattr *);
        int     (*mkdir)   (struct inode *, struct dentry *, struct iattr *);
        int     (*rmdir)   (struct inode *, struct qstr *);
        int     (*readdir) (struct dentry *, struct rpc_cred *,