1 files changed, 35 insertions, 11 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index d1060b8d3cd6..5dfc093ceb3d 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2379,7 +2379,8 @@ generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
         struct file *file = iocb->ki_filp;
         struct address_space *mapping = file->f_mapping;
         ssize_t retval;
-        size_t write_len = 0;
+        size_t write_len;
+        pgoff_t end = 0; /* silence gcc */
 
         /*
          * If it's a write, unmap all mmappings of the file up-front.  This
@@ -2388,23 +2389,46 @@ generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
          */
         if (rw == WRITE) {
                 write_len = iov_length(iov, nr_segs);
+                end = (offset + write_len - 1) >> PAGE_CACHE_SHIFT;
                 if (mapping_mapped(mapping))
                         unmap_mapping_range(mapping, offset, write_len, 0);
         }
 
         retval = filemap_write_and_wait(mapping);
-        if (retval == 0) {
-                retval = mapping->a_ops->direct_IO(rw, iocb, iov,
-                                                offset, nr_segs);
-                if (rw == WRITE && mapping->nrpages) {
-                        pgoff_t end = (offset + write_len - 1)
-                                                >> PAGE_CACHE_SHIFT;
-                        int err = invalidate_inode_pages2_range(mapping,
+        if (retval)
+                goto out;
+
+        /*
+         * After a write we want buffered reads to be sure to go to disk to get
+         * the new data.  We invalidate clean cached page from the region we're
+         * about to write.  We do this *before* the write so that we can return
+         * -EIO without clobbering -EIOCBQUEUED from ->direct_IO().
+         */
+        if (rw == WRITE && mapping->nrpages) {
+                retval = invalidate_inode_pages2_range(mapping,
                                         offset >> PAGE_CACHE_SHIFT, end);
-                        if (err)
-                                retval = err;
-                }
+                if (retval)
+                        goto out;
         }
+
+        retval = mapping->a_ops->direct_IO(rw, iocb, iov, offset, nr_segs);
+        if (retval)
+                goto out;
+
+        /*
+         * Finally, try again to invalidate clean pages which might have been
+         * faulted in by get_user_pages() if the source of the write was an
+         * mmap()ed region of the file we're writing.  That's a pretty crazy
+         * thing to do, so we don't support it 100%.  If this invalidation
+         * fails and we have -EIOCBQUEUED we ignore the failure.
+         */
+        if (rw == WRITE && mapping->nrpages) {
+                int err = invalidate_inode_pages2_range(mapping,
+                                              offset >> PAGE_CACHE_SHIFT, end);
+                if (err && retval >= 0)
+                        retval = err;
+        }
+out:
         return retval;
 }