NFSv4: Eliminate nfsv4 open race...

 Make NFSv4 return the fully initialized file pointer with the
 stateid that it created in the lookup w/intent.

 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 56 insertions, 81 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 35da15342e05..c9ecb8119632 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -47,6 +47,7 @@
 #include <linux/nfs_page.h>
 #include <linux/smp_lock.h>
 #include <linux/namei.h>
+#include <linux/mount.h>
 
 #include "nfs4_fs.h"
 #include "delegation.h"
@@ -947,12 +948,26 @@ out:
         return status;
 }
 
-struct inode *
+static void nfs4_intent_set_file(struct nameidata *nd, struct dentry *dentry, struct nfs4_state *state)
+{
+        struct file *filp;
+
+        filp = lookup_instantiate_filp(nd, dentry, NULL);
+        if (!IS_ERR(filp)) {
+                struct nfs_open_context *ctx;
+                ctx = (struct nfs_open_context *)filp->private_data;
+                ctx->state = state;
+        } else
+                nfs4_close_state(state, nd->intent.open.flags);
+}
+
+struct dentry *
 nfs4_atomic_open(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 {
         struct iattr attr;
         struct rpc_cred *cred;
         struct nfs4_state *state;
+        struct dentry *res;
 
         if (nd->flags & LOOKUP_CREATE) {
                 attr.ia_mode = nd->intent.open.create_mode;
@@ -966,16 +981,23 @@ nfs4_atomic_open(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 
         cred = rpcauth_lookupcred(NFS_SERVER(dir)->client->cl_auth, 0);
         if (IS_ERR(cred))
-                return (struct inode *)cred;
+                return (struct dentry *)cred;
         state = nfs4_do_open(dir, dentry, nd->intent.open.flags, &attr, cred);
         put_rpccred(cred);
-        if (IS_ERR(state))
-                return (struct inode *)state;
-        return state->inode;
+        if (IS_ERR(state)) {
+                if (PTR_ERR(state) == -ENOENT)
+                        d_add(dentry, NULL);
+                return (struct dentry *)state;
+        }
+        res = d_add_unique(dentry, state->inode);
+        if (res != NULL)
+                dentry = res;
+        nfs4_intent_set_file(nd, dentry, state);
+        return res;
 }
 
 int
-nfs4_open_revalidate(struct inode *dir, struct dentry *dentry, int openflags)
+nfs4_open_revalidate(struct inode *dir, struct dentry *dentry, int openflags, struct nameidata *nd)
 {
         struct rpc_cred *cred;
         struct nfs4_state *state;
@@ -988,18 +1010,30 @@ nfs4_open_revalidate(struct inode *dir, struct dentry *dentry, int openflags)
         if (IS_ERR(state))
                 state = nfs4_do_open(dir, dentry, openflags, NULL, cred);
         put_rpccred(cred);
-        if (state == ERR_PTR(-ENOENT) && dentry->d_inode == 0)
-                return 1;
-        if (IS_ERR(state))
-                return 0;
+        if (IS_ERR(state)) {
+                switch (PTR_ERR(state)) {
+                        case -EPERM:
+                        case -EACCES:
+                        case -EDQUOT:
+                        case -ENOSPC:
+                        case -EROFS:
+                                lookup_instantiate_filp(nd, (struct dentry *)state, NULL);
+                                return 1;
+                        case -ENOENT:
+                                if (dentry->d_inode == NULL)
+                                        return 1;
+                }
+                goto out_drop;
+        }
         inode = state->inode;
+        iput(inode);
         if (inode == dentry->d_inode) {
-                iput(inode);
+                nfs4_intent_set_file(nd, dentry, state);
                 return 1;
         }
-        d_drop(dentry);
         nfs4_close_state(state, openflags);
-        iput(inode);
+out_drop:
+        d_drop(dentry);
         return 0;
 }
 
@@ -1500,7 +1534,7 @@ static int nfs4_proc_commit(struct nfs_write_data *cdata)
 
 static int
 nfs4_proc_create(struct inode *dir, struct dentry *dentry, struct iattr *sattr,
-                 int flags)
+                 int flags, struct nameidata *nd)
 {
         struct nfs4_state *state;
         struct rpc_cred *cred;
@@ -1522,13 +1556,13 @@ nfs4_proc_create(struct inode *dir, struct dentry *dentry, struct iattr *sattr,
                 struct nfs_fattr fattr;
                 status = nfs4_do_setattr(NFS_SERVER(dir), &fattr,
                                      NFS_FH(state->inode), sattr, state);
-                if (status == 0) {
+                if (status == 0)
                         nfs_setattr_update_inode(state->inode, sattr);
-                        goto out;
-                }
-        } else if (flags != 0)
-                goto out;
-        nfs4_close_state(state, flags);
+        }
+        if (status == 0 && nd != NULL && (nd->flags & LOOKUP_OPEN))
+                nfs4_intent_set_file(nd, dentry, state);
+        else
+                nfs4_close_state(state, flags);
 out:
         return status;
 }
@@ -2175,65 +2209,6 @@ nfs4_proc_renew(struct nfs4_client *clp)
         return 0;
 }
 
-/*
- * We will need to arrange for the VFS layer to provide an atomic open.
- * Until then, this open method is prone to inefficiency and race conditions
- * due to the lookup, potential create, and open VFS calls from sys_open()
- * placed on the wire.
- */
-static int
-nfs4_proc_file_open(struct inode *inode, struct file *filp)
-{
-        struct dentry *dentry = filp->f_dentry;
-        struct nfs_open_context *ctx;
-        struct nfs4_state *state = NULL;
-        struct rpc_cred *cred;
-        int status = -ENOMEM;
-
-        dprintk("nfs4_proc_file_open: starting on (%.*s/%.*s)\n",
-                               (int)dentry->d_parent->d_name.len,
-                               dentry->d_parent->d_name.name,
-                               (int)dentry->d_name.len, dentry->d_name.name);
-
-
-        /* Find our open stateid */
-        cred = rpcauth_lookupcred(NFS_SERVER(inode)->client->cl_auth, 0);
-        if (IS_ERR(cred))
-                return PTR_ERR(cred);
-        ctx = alloc_nfs_open_context(dentry, cred);
-        put_rpccred(cred);
-        if (unlikely(ctx == NULL))
-                return -ENOMEM;
-        status = -EIO; /* ERACE actually */
-        state = nfs4_find_state(inode, cred, filp->f_mode);
-        if (unlikely(state == NULL))
-                goto no_state;
-        ctx->state = state;
-        nfs4_close_state(state, filp->f_mode);
-        ctx->mode = filp->f_mode;
-        nfs_file_set_open_context(filp, ctx);
-        put_nfs_open_context(ctx);
-        if (filp->f_mode & FMODE_WRITE)
-                nfs_begin_data_update(inode);
-        return 0;
-no_state:
-        printk(KERN_WARNING "NFS: v4 raced in function %s\n", __FUNCTION__);
-        put_nfs_open_context(ctx);
-        return status;
-}
-
-/*
- * Release our state
- */
-static int
-nfs4_proc_file_release(struct inode *inode, struct file *filp)
-{
-        if (filp->f_mode & FMODE_WRITE)
-                nfs_end_data_update(inode);
-        nfs_file_clear_open_context(filp);
-        return 0;
-}
-
 static inline int nfs4_server_supports_acls(struct nfs_server *server)
 {
         return (server->caps & NFS_CAP_ACLS)
@@ -3145,8 +3120,8 @@ struct nfs_rpc_ops	nfs_v4_clientops = {
         .read_setup     = nfs4_proc_read_setup,
         .write_setup    = nfs4_proc_write_setup,
         .commit_setup   = nfs4_proc_commit_setup,
-        .file_open      = nfs4_proc_file_open,
-        .file_release   = nfs4_proc_file_release,
+        .file_open      = nfs_open,
+        .file_release   = nfs_release,
         .lock           = nfs4_proc_lock,
         .clear_acl_cache = nfs4_zap_acl_attr,
 };