Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6: (25 commits)
  cifs: remove unnecessary dentry_unhash on rmdir/rename_dir
  ocfs2: remove unnecessary dentry_unhash on rmdir/rename_dir
  exofs: remove unnecessary dentry_unhash on rmdir/rename_dir
  nfs: remove unnecessary dentry_unhash on rmdir/rename_dir
  ext2: remove unnecessary dentry_unhash on rmdir/rename_dir
  ext3: remove unnecessary dentry_unhash on rmdir/rename_dir
  ext4: remove unnecessary dentry_unhash on rmdir/rename_dir
  btrfs: remove unnecessary dentry_unhash in rmdir/rename_dir
  ceph: remove unnecessary dentry_unhash calls
  vfs: clean up vfs_rename_other
  vfs: clean up vfs_rename_dir
  vfs: clean up vfs_rmdir
  vfs: fix vfs_rename_dir for FS_RENAME_DOES_D_MOVE filesystems
  libfs: drop unneeded dentry_unhash
  vfs: update dentry_unhash() comment
  vfs: push dentry_unhash on rename_dir into file systems
  vfs: push dentry_unhash on rmdir into file systems
  vfs: remove dget() from dentry_unhash()
  vfs: dentry_unhash immediately prior to rmdir
  vfs: Block mmapped writes while the fs is frozen
  ...

1 files changed, 42 insertions, 17 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index a08bb8e61c6f..b0675bfe8207 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2331,24 +2331,26 @@ EXPORT_SYMBOL(block_commit_write);
  * page lock we can determine safely if the page is beyond EOF. If it is not
  * beyond EOF, then the page is guaranteed safe against truncation until we
  * unlock the page.
+ *
+ * Direct callers of this function should call vfs_check_frozen() so that page
+ * fault does not busyloop until the fs is thawed.
  */
-int
-block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
-                   get_block_t get_block)
+int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
+                         get_block_t get_block)
 {
         struct page *page = vmf->page;
         struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
         unsigned long end;
         loff_t size;
-        int ret = VM_FAULT_NOPAGE; /* make the VM retry the fault */
+        int ret;
 
         lock_page(page);
         size = i_size_read(inode);
         if ((page->mapping != inode->i_mapping) ||
             (page_offset(page) > size)) {
-                /* page got truncated out from underneath us */
-                unlock_page(page);
-                goto out;
+                /* We overload EFAULT to mean page got truncated */
+                ret = -EFAULT;
+                goto out_unlock;
         }
 
         /* page is wholly or partially inside EOF */
@@ -2361,18 +2363,41 @@ block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
         if (!ret)
                 ret = block_commit_write(page, 0, end);
 
-        if (unlikely(ret)) {
-                unlock_page(page);
-                if (ret == -ENOMEM)
-                        ret = VM_FAULT_OOM;
-                else /* -ENOSPC, -EIO, etc */
-                        ret = VM_FAULT_SIGBUS;
-        } else
-                ret = VM_FAULT_LOCKED;
-
-out:
+        if (unlikely(ret < 0))
+                goto out_unlock;
+        /*
+         * Freezing in progress? We check after the page is marked dirty and
+         * with page lock held so if the test here fails, we are sure freezing
+         * code will wait during syncing until the page fault is done - at that
+         * point page will be dirty and unlocked so freezing code will write it
+         * and writeprotect it again.
+         */
+        set_page_dirty(page);
+        if (inode->i_sb->s_frozen != SB_UNFROZEN) {
+                ret = -EAGAIN;
+                goto out_unlock;
+        }
+        return 0;
+out_unlock:
+        unlock_page(page);
         return ret;
 }
+EXPORT_SYMBOL(__block_page_mkwrite);
+
+int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
+                   get_block_t get_block)
+{
+        int ret;
+        struct super_block *sb = vma->vm_file->f_path.dentry->d_inode->i_sb;
+
+        /*
+         * This check is racy but catches the common case. The check in
+         * __block_page_mkwrite() is reliable.
+         */
+        vfs_check_frozen(sb, SB_FREEZE_WRITE);
+        ret = __block_page_mkwrite(vma, vmf, get_block);
+        return block_page_mkwrite_return(ret);
+}
 EXPORT_SYMBOL(block_page_mkwrite);
 
 /*