pull mnt_want_write()/mnt_drop_write() into kern_path_create()/done_path_create(...

One side effect - attempt to create a cross-device link on a read-only fs fails
with EROFS instead of EXDEV now.  Makes more sense, POSIX allows, etc.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/namei.c b/fs/namei.c
index cf362dc..a3fb78f 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2865,10 +2865,11 @@ struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path
        mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
        dentry = lookup_hash(&nd);
        if (IS_ERR(dentry))
-               goto fail;
+               goto unlock;
 
+       error = -EEXIST;
        if (dentry->d_inode)
-               goto eexist;
+               goto fail;
        /*
         * Special case - lookup gave negative, but... we had foo/bar/
         * From the vfs_mknod() POV we just have a negative dentry -
@@ -2876,16 +2877,18 @@ struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path
         * been asking for (non-existent) directory. -ENOENT for you.
         */
        if (unlikely(!is_dir && nd.last.name[nd.last.len])) {
-               dput(dentry);
-               dentry = ERR_PTR(-ENOENT);
+               error = -ENOENT;
                goto fail;
        }
+       error = mnt_want_write(nd.path.mnt);
+       if (error)
+               goto fail;
        *path = nd.path;
        return dentry;
-eexist:
-       dput(dentry);
-       dentry = ERR_PTR(-EEXIST);
 fail:
+       dput(dentry);
+       dentry = ERR_PTR(error);
+unlock:
        mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
 out:
        path_put(&nd.path);
@@ -2897,6 +2900,7 @@ void done_path_create(struct path *path, struct dentry *dentry)
 {
        dput(dentry);
        mutex_unlock(&path->dentry->d_inode->i_mutex);
+       mnt_drop_write(path->mnt);
        path_put(path);
 }
 EXPORT_SYMBOL(done_path_create);
@@ -2974,12 +2978,9 @@ SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode,
 
        if (!IS_POSIXACL(path.dentry->d_inode))
                mode &= ~current_umask();
-       error = mnt_want_write(path.mnt);
-       if (error)
-               goto out_dput;
        error = security_path_mknod(&path, dentry, mode, dev);
        if (error)
-               goto out_drop_write;
+               goto out;
        switch (mode & S_IFMT) {
                case 0: case S_IFREG:
                        error = vfs_create(path.dentry->d_inode,dentry,mode,true);
@@ -2992,11 +2993,8 @@ SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode,
                        error = vfs_mknod(path.dentry->d_inode,dentry,mode,0);
                        break;
        }
-out_drop_write:
-       mnt_drop_write(path.mnt);
-out_dput:
+out:
        done_path_create(&path, dentry);
-
        return error;
 }
 
@@ -3042,16 +3040,9 @@ SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode)
 
        if (!IS_POSIXACL(path.dentry->d_inode))
                mode &= ~current_umask();
-       error = mnt_want_write(path.mnt);
-       if (error)
-               goto out_dput;
        error = security_path_mkdir(&path, dentry, mode);
-       if (error)
-               goto out_drop_write;
-       error = vfs_mkdir(path.dentry->d_inode, dentry, mode);
-out_drop_write:
-       mnt_drop_write(path.mnt);
-out_dput:
+       if (!error)
+               error = vfs_mkdir(path.dentry->d_inode, dentry, mode);
        done_path_create(&path, dentry);
        return error;
 }
@@ -3326,16 +3317,9 @@ SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
        if (IS_ERR(dentry))
                goto out_putname;
 
-       error = mnt_want_write(path.mnt);
-       if (error)
-               goto out_dput;
        error = security_path_symlink(&path, dentry, from);
-       if (error)
-               goto out_drop_write;
-       error = vfs_symlink(path.dentry->d_inode, dentry, from);
-out_drop_write:
-       mnt_drop_write(path.mnt);
-out_dput:
+       if (!error)
+               error = vfs_symlink(path.dentry->d_inode, dentry, from);
        done_path_create(&path, dentry);
 out_putname:
        putname(from);
@@ -3436,15 +3420,10 @@ SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
        error = -EXDEV;
        if (old_path.mnt != new_path.mnt)
                goto out_dput;
-       error = mnt_want_write(new_path.mnt);
-       if (error)
-               goto out_dput;
        error = security_path_link(old_path.dentry, &new_path, new_dentry);
        if (error)
-               goto out_drop_write;
+               goto out_dput;
        error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry);
-out_drop_write:
-       mnt_drop_write(new_path.mnt);
 out_dput:
        done_path_create(&new_path, new_dentry);
 out:

diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 23cf78f..30a0550 100644 (file)
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -4466,16 +4466,9 @@ int ocfs2_reflink_ioctl(struct inode *inode,
                goto out_dput;
        }
 
-       error = mnt_want_write(new_path.mnt);
-       if (error) {
-               mlog_errno(error);
-               goto out_dput;
-       }
-
        error = ocfs2_vfs_reflink(old_path.dentry,
                                  new_path.dentry->d_inode,
                                  new_dentry, preserve);
-       mnt_drop_write(new_path.mnt);
 out_dput:
        done_path_create(&new_path, new_dentry);
 out:

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index e823954..88ab728 100644 (file)
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -876,15 +876,11 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
                 */
                mode = S_IFSOCK |
                       (SOCK_INODE(sock)->i_mode & ~current_umask());
-               err = mnt_want_write(path.mnt);
-               if (err)
-                       goto out_mknod_dput;
                err = security_path_mknod(&path, dentry, mode, 0);
                if (err)
                        goto out_mknod_drop_write;
                err = vfs_mknod(path.dentry->d_inode, dentry, mode, 0);
 out_mknod_drop_write:
-               mnt_drop_write(path.mnt);
                if (err)
                        goto out_mknod_dput;
                mntget(path.mnt);