NFSv4.1/pnfs: Fix atomicity of commit list updates

pnfs_layout_mark_request_commit() needs to ensure that it adds the
request to the commit list atomically with all the other updates
in order to prevent corruption to buckets[ds_commit_idx].wlseg
due to races with pnfs_generic_clear_request_commit().

Fixes: 338d00cfef07d ("pnfs: Refactor the *_layout_mark_request_commit...")
Cc: stable@vger.kernel.org # v4.0+
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

1 files changed, 24 insertions, 5 deletions

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 75a35a1afa79..fdee9270ca15 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -768,6 +768,28 @@ nfs_page_search_commits_for_head_request_locked(struct nfs_inode *nfsi,
 }
 
 /**
+ * nfs_request_add_commit_list_locked - add request to a commit list
+ * @req: pointer to a struct nfs_page
+ * @dst: commit list head
+ * @cinfo: holds list lock and accounting info
+ *
+ * This sets the PG_CLEAN bit, updates the cinfo count of
+ * number of outstanding requests requiring a commit as well as
+ * the MM page stats.
+ *
+ * The caller must hold the cinfo->lock, and the nfs_page lock.
+ */
+void
+nfs_request_add_commit_list_locked(struct nfs_page *req, struct list_head *dst,
+                            struct nfs_commit_info *cinfo)
+{
+        set_bit(PG_CLEAN, &req->wb_flags);
+        nfs_list_add_request(req, dst);
+        cinfo->mds->ncommit++;
+}
+EXPORT_SYMBOL_GPL(nfs_request_add_commit_list_locked);
+
+/**
  * nfs_request_add_commit_list - add request to a commit list
  * @req: pointer to a struct nfs_page
  * @dst: commit list head
@@ -784,13 +806,10 @@ void
 nfs_request_add_commit_list(struct nfs_page *req, struct list_head *dst,
                             struct nfs_commit_info *cinfo)
 {
-        set_bit(PG_CLEAN, &(req)->wb_flags);
         spin_lock(cinfo->lock);
-        nfs_list_add_request(req, dst);
-        cinfo->mds->ncommit++;
+        nfs_request_add_commit_list_locked(req, dst, cinfo);
         spin_unlock(cinfo->lock);
-        if (!cinfo->dreq)
-                nfs_mark_page_unstable(req->wb_page);
+        nfs_mark_page_unstable(req->wb_page, cinfo);
 }
 EXPORT_SYMBOL_GPL(nfs_request_add_commit_list);