[PATCH] splice: redo page lookup if add_to_page_cache() returns -EEXIST

This can happen quite easily, if several processes are trying to splice
the same file at the same time. It's not a failure, it just means someone
raced with us in allocating this file page. So just dump the allocated
page and relookup the original.

Signed-off-by: Jens Axboe <axboe@suse.de>

diff --git a/fs/splice.c b/fs/splice.c
index 8fa9217..a285fd7 100644 (file)
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -324,6 +324,8 @@ __generic_file_splice_read(struct file *in, loff_t *ppos,
                                              mapping_gfp_mask(mapping));
                        if (unlikely(error)) {
                                page_cache_release(page);
+                               if (error == -EEXIST)
+                                       continue;
                                break;
                        }
                        /*