[PATCH] r/o bind mounts: write counts for truncate()

Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 8 insertions, 6 deletions

diff --git a/fs/open.c b/fs/open.c
index e2df8fd1eb0b..4d690e33446f 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -244,21 +244,21 @@ static long do_sys_truncate(const char __user * path, loff_t length)
         if (!S_ISREG(inode->i_mode))
                 goto dput_and_out;
 
-        error = vfs_permission(&nd, MAY_WRITE);
+        error = mnt_want_write(nd.path.mnt);
         if (error)
                 goto dput_and_out;
 
-        error = -EROFS;
-        if (IS_RDONLY(inode))
-                goto dput_and_out;
+        error = vfs_permission(&nd, MAY_WRITE);
+        if (error)
+                goto mnt_drop_write_and_out;
 
         error = -EPERM;
         if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
-                goto dput_and_out;
+                goto mnt_drop_write_and_out;
 
         error = get_write_access(inode);
         if (error)
-                goto dput_and_out;
+                goto mnt_drop_write_and_out;
 
         /*
          * Make sure that there are no leases.  get_write_access() protects
@@ -276,6 +276,8 @@ static long do_sys_truncate(const char __user * path, loff_t length)
 
 put_write_and_out:
         put_write_access(inode);
+mnt_drop_write_and_out:
+        mnt_drop_write(nd.path.mnt);
 dput_and_out:
         path_put(&nd.path);
 out: