NFS: Reduce the NFS mount code stack usage.

This appears to fix the Oops reported in
  http://bugzilla.kernel.org/show_bug.cgi?id=10826

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

1 files changed, 40 insertions, 28 deletions

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 2a4a024a4e7b..dac663dc5611 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -1216,8 +1216,6 @@ static int nfs_validate_mount_data(void *options,
 {
         struct nfs_mount_data *data = (struct nfs_mount_data *)options;
 
-        memset(args, 0, sizeof(*args));
-
         if (data == NULL)
                 goto out_no_data;
 
@@ -1585,24 +1583,29 @@ static int nfs_get_sb(struct file_system_type *fs_type,
 {
         struct nfs_server *server = NULL;
         struct super_block *s;
-        struct nfs_fh mntfh;
-        struct nfs_parsed_mount_data data;
+        struct nfs_parsed_mount_data *data;
+        struct nfs_fh *mntfh;
         struct dentry *mntroot;
         int (*compare_super)(struct super_block *, void *) = nfs_compare_super;
         struct nfs_sb_mountdata sb_mntdata = {
                 .mntflags = flags,
         };
-        int error;
+        int error = -ENOMEM;
 
-        security_init_mnt_opts(&data.lsm_opts);
+        data = kzalloc(sizeof(*data), GFP_KERNEL);
+        mntfh = kzalloc(sizeof(*mntfh), GFP_KERNEL);
+        if (data == NULL || mntfh == NULL)
+                goto out_free_fh;
+
+        security_init_mnt_opts(&data->lsm_opts);
 
         /* Validate the mount data */
-        error = nfs_validate_mount_data(raw_data, &data, &mntfh, dev_name);
+        error = nfs_validate_mount_data(raw_data, data, mntfh, dev_name);
         if (error < 0)
                 goto out;
 
         /* Get a volume representation */
-        server = nfs_create_server(&data, &mntfh);
+        server = nfs_create_server(data, mntfh);
         if (IS_ERR(server)) {
                 error = PTR_ERR(server);
                 goto out;
@@ -1630,16 +1633,16 @@ static int nfs_get_sb(struct file_system_type *fs_type,
 
         if (!s->s_root) {
                 /* initial superblock/root creation */
-                nfs_fill_super(s, &data);
+                nfs_fill_super(s, data);
         }
 
-        mntroot = nfs_get_root(s, &mntfh);
+        mntroot = nfs_get_root(s, mntfh);
         if (IS_ERR(mntroot)) {
                 error = PTR_ERR(mntroot);
                 goto error_splat_super;
         }
 
-        error = security_sb_set_mnt_opts(s, &data.lsm_opts);
+        error = security_sb_set_mnt_opts(s, &data->lsm_opts);
         if (error)
                 goto error_splat_root;
 
@@ -1649,9 +1652,12 @@ static int nfs_get_sb(struct file_system_type *fs_type,
         error = 0;
 
 out:
-        kfree(data.nfs_server.hostname);
-        kfree(data.mount_server.hostname);
-        security_free_mnt_opts(&data.lsm_opts);
+        kfree(data->nfs_server.hostname);
+        kfree(data->mount_server.hostname);
+        security_free_mnt_opts(&data->lsm_opts);
+out_free_fh:
+        kfree(mntfh);
+        kfree(data);
         return error;
 
 out_err_nosb:
@@ -1800,8 +1806,6 @@ static int nfs4_validate_mount_data(void *options,
         struct nfs4_mount_data *data = (struct nfs4_mount_data *)options;
         char *c;
 
-        memset(args, 0, sizeof(*args));
-
         if (data == NULL)
                 goto out_no_data;
 
@@ -1959,26 +1963,31 @@ out_no_client_address:
 static int nfs4_get_sb(struct file_system_type *fs_type,
         int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt)
 {
-        struct nfs_parsed_mount_data data;
+        struct nfs_parsed_mount_data *data;
         struct super_block *s;
         struct nfs_server *server;
-        struct nfs_fh mntfh;
+        struct nfs_fh *mntfh;
         struct dentry *mntroot;
         int (*compare_super)(struct super_block *, void *) = nfs_compare_super;
         struct nfs_sb_mountdata sb_mntdata = {
                 .mntflags = flags,
         };
-        int error;
+        int error = -ENOMEM;
 
-        security_init_mnt_opts(&data.lsm_opts);
+        data = kzalloc(sizeof(*data), GFP_KERNEL);
+        mntfh = kzalloc(sizeof(*mntfh), GFP_KERNEL);
+        if (data == NULL || mntfh == NULL)
+                goto out_free_fh;
+
+        security_init_mnt_opts(&data->lsm_opts);
 
         /* Validate the mount data */
-        error = nfs4_validate_mount_data(raw_data, &data, dev_name);
+        error = nfs4_validate_mount_data(raw_data, data, dev_name);
         if (error < 0)
                 goto out;
 
         /* Get a volume representation */
-        server = nfs4_create_server(&data, &mntfh);
+        server = nfs4_create_server(data, mntfh);
         if (IS_ERR(server)) {
                 error = PTR_ERR(server);
                 goto out;
@@ -2009,13 +2018,13 @@ static int nfs4_get_sb(struct file_system_type *fs_type,
                 nfs4_fill_super(s);
         }
 
-        mntroot = nfs4_get_root(s, &mntfh);
+        mntroot = nfs4_get_root(s, mntfh);
         if (IS_ERR(mntroot)) {
                 error = PTR_ERR(mntroot);
                 goto error_splat_super;
         }
 
-        error = security_sb_set_mnt_opts(s, &data.lsm_opts);
+        error = security_sb_set_mnt_opts(s, &data->lsm_opts);
         if (error)
                 goto error_splat_root;
 
@@ -2025,10 +2034,13 @@ static int nfs4_get_sb(struct file_system_type *fs_type,
         error = 0;
 
 out:
-        kfree(data.client_address);
-        kfree(data.nfs_server.export_path);
-        kfree(data.nfs_server.hostname);
-        security_free_mnt_opts(&data.lsm_opts);
+        kfree(data->client_address);
+        kfree(data->nfs_server.export_path);
+        kfree(data->nfs_server.hostname);
+        security_free_mnt_opts(&data->lsm_opts);
+out_free_fh:
+        kfree(mntfh);
+        kfree(data);
         return error;
 
 out_free: