[Linux-cachefs] Yet another trace from a crash

[David Howells]

Can you try this patch instead?

David
---
From: David Howells <dhowells at redhat.com>
Subject: [PATCH] FS-Cache: Debug the Bad Page state


---

 fs/cachefiles/rdwr.c          |   20 ++++++++++----------
 fs/fscache/page.c             |   19 ++++++++++++++++++-
 include/linux/fscache-cache.h |    3 ++-
 3 files changed, 30 insertions(+), 12 deletions(-)


diff --git a/fs/cachefiles/rdwr.c b/fs/cachefiles/rdwr.c
index 0f0d41f..acff835 100644
--- a/fs/cachefiles/rdwr.c
+++ b/fs/cachefiles/rdwr.c
@@ -178,7 +178,7 @@ static void cachefiles_read_copier(struct fscache_operation *_op)
 			copy_highpage(monitor->netfs_page, monitor->back_page);
 
 			pagevec_add(&pagevec, monitor->netfs_page);
-			fscache_mark_pages_cached(monitor->op, &pagevec);
+			fscache_mark_pages_cached(monitor->op, &pagevec, true);
 			error = 0;
 		} else if (!PageError(monitor->back_page)) {
 			/* the page has probably been truncated */
@@ -336,7 +336,7 @@ backing_page_already_uptodate:
 	_debug("- uptodate");
 
 	pagevec_add(pagevec, netpage);
-	fscache_mark_pages_cached(op, pagevec);
+	fscache_mark_pages_cached(op, pagevec, true);
 
 	copy_highpage(netpage, backpage);
 	fscache_end_io(op, netpage, 0);
@@ -449,7 +449,7 @@ int cachefiles_read_or_alloc_page(struct fscache_retrieval *op,
 	} else if (cachefiles_has_space(cache, 0, 1) == 0) {
 		/* there's space in the cache we can use */
 		pagevec_add(&pagevec, page);
-		fscache_mark_pages_cached(op, &pagevec);
+		fscache_mark_pages_cached(op, &pagevec, true);
 		ret = -ENODATA;
 	} else {
 		ret = -ENOBUFS;
@@ -627,7 +627,7 @@ static int cachefiles_read_backing_file(struct cachefiles_object *object,
 		backpage = NULL;
 
 		if (!pagevec_add(mark_pvec, netpage))
-			fscache_mark_pages_cached(op, mark_pvec);
+			fscache_mark_pages_cached(op, mark_pvec, true);
 
 		page_cache_get(netpage);
 		if (!pagevec_add(&lru_pvec, netpage))
@@ -761,13 +761,13 @@ int cachefiles_read_or_alloc_pages(struct fscache_retrieval *op,
 			(*nr_pages)--;
 			nrbackpages++;
 		} else if (space && pagevec_add(&pagevec, page) == 0) {
-			fscache_mark_pages_cached(op, &pagevec);
+			fscache_mark_pages_cached(op, &pagevec, false);
 			ret = -ENODATA;
 		}
 	}
 
 	if (pagevec_count(&pagevec) > 0)
-		fscache_mark_pages_cached(op, &pagevec);
+		fscache_mark_pages_cached(op, &pagevec, false);
 
 	if (list_empty(pages))
 		ret = 0;
@@ -782,7 +782,7 @@ int cachefiles_read_or_alloc_pages(struct fscache_retrieval *op,
 	}
 
 	if (pagevec_count(&pagevec) > 0)
-		fscache_mark_pages_cached(op, &pagevec);
+		fscache_mark_pages_cached(op, &pagevec, true);
 
 	_leave(" = %d [nr=%u%s]",
 	       ret, *nr_pages, list_empty(pages) ? " empty" : "");
@@ -820,7 +820,7 @@ int cachefiles_allocate_page(struct fscache_retrieval *op,
 	if (ret == 0) {
 		pagevec_init(&pagevec, 0);
 		pagevec_add(&pagevec, page);
-		fscache_mark_pages_cached(op, &pagevec);
+		fscache_mark_pages_cached(op, &pagevec, false);
 	} else {
 		ret = -ENOBUFS;
 	}
@@ -864,11 +864,11 @@ int cachefiles_allocate_pages(struct fscache_retrieval *op,
 
 		list_for_each_entry(page, pages, lru) {
 			if (pagevec_add(&pagevec, page) == 0)
-				fscache_mark_pages_cached(op, &pagevec);
+				fscache_mark_pages_cached(op, &pagevec, false);
 		}
 
 		if (pagevec_count(&pagevec) > 0)
-			fscache_mark_pages_cached(op, &pagevec);
+			fscache_mark_pages_cached(op, &pagevec, false);
 		ret = -ENODATA;
 	} else {
 		ret = -ENOBUFS;
diff --git a/fs/fscache/page.c b/fs/fscache/page.c
index 47aefd3..9461617 100644
--- a/fs/fscache/page.c
+++ b/fs/fscache/page.c
@@ -955,12 +955,14 @@ EXPORT_SYMBOL(__fscache_uncache_page);
  * fscache_mark_pages_cached - Mark pages as being cached
  * @op: The retrieval op pages are being marked for
  * @pagevec: The pages to be marked
+ * @should_have_mapping: True if the pages should have a mapping set
  *
  * Mark a bunch of netfs pages as being cached.  After this is called,
  * the netfs must call fscache_uncache_page() to remove the mark.
  */
 void fscache_mark_pages_cached(struct fscache_retrieval *op,
-			       struct pagevec *pagevec)
+			       struct pagevec *pagevec,
+			       bool should_have_mapping)
 {
 	struct fscache_cookie *cookie = op->op.object->cookie;
 	unsigned long loop;
@@ -983,6 +985,21 @@ void fscache_mark_pages_cached(struct fscache_retrieval *op,
 				       cookie->def->name, page->index);
 			}
 		}
+		if ((should_have_mapping && !page->mapping) ||
+		    (!should_have_mapping && page->mapping)) {
+			static bool once_only;
+			if (once_only)
+				goto skip;
+			once_only = 1;
+			printk(KERN_ALERT
+			       "page:%p count:%d mapcount:%d mapping:%p index:%#lx\n",
+			       page, page_count(page), page_mapcount(page),
+			       page->mapping, page->index);
+			WARN_ON(1);
+		skip:
+			;
+		}
+
 	}
 
 	if (cookie->def->mark_pages_cached)
diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h
index c57db27..762b3f7 100644
--- a/include/linux/fscache-cache.h
+++ b/include/linux/fscache-cache.h
@@ -532,7 +532,8 @@ extern void fscache_withdraw_cache(struct fscache_cache *cache);
 extern void fscache_io_error(struct fscache_cache *cache);
 
 extern void fscache_mark_pages_cached(struct fscache_retrieval *op,
-				      struct pagevec *pagevec);
+				      struct pagevec *pagevec,
+				      bool should_have_mapping);
 
 extern enum fscache_checkaux fscache_check_aux(struct fscache_object *object,
 					       const void *data,