tools headers UAPI: Sync openat2.h with the kernel sources

[linux-2.6-microblaze.git] / fs / namespace.c

diff --git a/fs/namespace.c b/fs/namespace.c
index 062fe98..56bb5a5 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -380,51 +380,37 @@ int mnt_want_write(struct vfsmount *m)
 }
 EXPORT_SYMBOL_GPL(mnt_want_write);
 
-/**
- * mnt_clone_write - get write access to a mount
- * @mnt: the mount on which to take a write
- *
- * This is effectively like mnt_want_write, except
- * it must only be used to take an extra write reference
- * on a mountpoint that we already know has a write reference
- * on it. This allows some optimisation.
- *
- * After finished, mnt_drop_write must be called as usual to
- * drop the reference.
- */
-int mnt_clone_write(struct vfsmount *mnt)
-{
-       /* superblock may be r/o */
-       if (__mnt_is_readonly(mnt))
-               return -EROFS;
-       preempt_disable();
-       mnt_inc_writers(real_mount(mnt));
-       preempt_enable();
-       return 0;
-}
-EXPORT_SYMBOL_GPL(mnt_clone_write);
-
 /**
  * __mnt_want_write_file - get write access to a file's mount
  * @file: the file who's mount on which to take a write
  *
- * This is like __mnt_want_write, but it takes a file and can
- * do some optimisations if the file is open for write already
+ * This is like __mnt_want_write, but if the file is already open for writing it
+ * skips incrementing mnt_writers (since the open file already has a reference)
+ * and instead only does the check for emergency r/o remounts.  This must be
+ * paired with __mnt_drop_write_file.
  */
 int __mnt_want_write_file(struct file *file)
 {
-       if (!(file->f_mode & FMODE_WRITER))
-               return __mnt_want_write(file->f_path.mnt);
-       else
-               return mnt_clone_write(file->f_path.mnt);
+       if (file->f_mode & FMODE_WRITER) {
+               /*
+                * Superblock may have become readonly while there are still
+                * writable fd's, e.g. due to a fs error with errors=remount-ro
+                */
+               if (__mnt_is_readonly(file->f_path.mnt))
+                       return -EROFS;
+               return 0;
+       }
+       return __mnt_want_write(file->f_path.mnt);
 }
 
 /**
  * mnt_want_write_file - get write access to a file's mount
  * @file: the file who's mount on which to take a write
  *
- * This is like mnt_want_write, but it takes a file and can
- * do some optimisations if the file is open for write already
+ * This is like mnt_want_write, but if the file is already open for writing it
+ * skips incrementing mnt_writers (since the open file already has a reference)
+ * and instead only does the freeze protection and the check for emergency r/o
+ * remounts.  This must be paired with mnt_drop_write_file.
  */
 int mnt_want_write_file(struct file *file)
 {
@@ -470,7 +456,8 @@ EXPORT_SYMBOL_GPL(mnt_drop_write);
 
 void __mnt_drop_write_file(struct file *file)
 {
-       __mnt_drop_write(file->f_path.mnt);
+       if (!(file->f_mode & FMODE_WRITER))
+               __mnt_drop_write(file->f_path.mnt);
 }
 
 void mnt_drop_write_file(struct file *file)