vfs: Create __block_page_mkwrite() helper passing error values back

Create __block_page_mkwrite() helper which does all what block_page_mkwrite()
does except that it passes back errors from __block_write_begin /
block_commit_write calls.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 20 insertions, 17 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index a08bb8e61c6f..f6ad8f9b8fa5 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2332,23 +2332,22 @@ EXPORT_SYMBOL(block_commit_write);
  * beyond EOF, then the page is guaranteed safe against truncation until we
  * unlock the page.
  */
-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 +2360,22 @@ 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;
+        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 = __block_page_mkwrite(vma, vmf, get_block);
+
+        return block_page_mkwrite_return(ret);
+}
 EXPORT_SYMBOL(block_page_mkwrite);
 
 /*