NFS: Replace __nfs_write_mapping with sync_inode()

Now that we have correct COMMIT semantics in writeback_single_inode, we can
reduce and simplify nfs_wb_all(). Also replace nfs_wb_nocommit() with a
call to filemap_write_and_wait(), which doesn't need to hold the
inode->i_mutex.

With that done, we can eliminate nfs_write_mapping() altogether.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

3 files changed, 10 insertions, 49 deletions

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index aa5a831001ab..443772df9b17 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -495,17 +495,11 @@ int nfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
         int need_atime = NFS_I(inode)->cache_validity & NFS_INO_INVALID_ATIME;
         int err;
 
-        /*
-         * Flush out writes to the server in order to update c/mtime.
-         *
-         * Hold the i_mutex to suspend application writes temporarily;
-         * this prevents long-running writing applications from blocking
-         * nfs_wb_nocommit.
-         */
+        /* Flush out writes to the server in order to update c/mtime.  */
         if (S_ISREG(inode->i_mode)) {
-                mutex_lock(&inode->i_mutex);
-                nfs_wb_nocommit(inode);
-                mutex_unlock(&inode->i_mutex);
+                err = filemap_write_and_wait(inode->i_mapping);
+                if (err)
+                        goto out;
         }
 
         /*
@@ -529,6 +523,7 @@ int nfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
                 generic_fillattr(inode, stat);
                 stat->ino = nfs_compat_user_ino64(NFS_FILEID(inode));
         }
+out:
         return err;
 }
 
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index dc7f5e9a23b4..0b323091b481 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1454,7 +1454,6 @@ long nfs_sync_mapping_wait(struct address_space *mapping, struct writeback_contr
         pgoff_t idx_start, idx_end;
         unsigned int npages = 0;
         LIST_HEAD(head);
-        int nocommit = how & FLUSH_NOCOMMIT;
         long pages, ret;
 
         /* FIXME */
@@ -1471,14 +1470,11 @@ long nfs_sync_mapping_wait(struct address_space *mapping, struct writeback_contr
                                 npages = 0;
                 }
         }
-        how &= ~FLUSH_NOCOMMIT;
         spin_lock(&inode->i_lock);
         do {
                 ret = nfs_wait_on_requests_locked(inode, idx_start, npages);
                 if (ret != 0)
                         continue;
-                if (nocommit)
-                        break;
                 pages = nfs_scan_commit(inode, &head, idx_start, npages);
                 if (pages == 0)
                         break;
@@ -1492,47 +1488,19 @@ long nfs_sync_mapping_wait(struct address_space *mapping, struct writeback_contr
         return ret;
 }
 
-static int __nfs_write_mapping(struct address_space *mapping, struct writeback_control *wbc, int how)
-{
-        int ret;
-
-        ret = nfs_writepages(mapping, wbc);
-        if (ret < 0)
-                goto out;
-        ret = nfs_sync_mapping_wait(mapping, wbc, how);
-        if (ret < 0)
-                goto out;
-        return 0;
-out:
-        __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
-        return ret;
-}
-
-/* Two pass sync: first using WB_SYNC_NONE, then WB_SYNC_ALL */
-static int nfs_write_mapping(struct address_space *mapping, int how)
+/*
+ * flush the inode to disk.
+ */
+int nfs_wb_all(struct inode *inode)
 {
         struct writeback_control wbc = {
-                .bdi = mapping->backing_dev_info,
                 .sync_mode = WB_SYNC_ALL,
                 .nr_to_write = LONG_MAX,
                 .range_start = 0,
                 .range_end = LLONG_MAX,
         };
 
-        return __nfs_write_mapping(mapping, &wbc, how);
-}
-
-/*
- * flush the inode to disk.
- */
-int nfs_wb_all(struct inode *inode)
-{
-        return nfs_write_mapping(inode->i_mapping, 0);
-}
-
-int nfs_wb_nocommit(struct inode *inode)
-{
-        return nfs_write_mapping(inode->i_mapping, FLUSH_NOCOMMIT);
+        return sync_inode(inode, &wbc);
 }
 
 int nfs_wb_page_cancel(struct inode *inode, struct page *page)
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 1083134c02ff..93f439e7c5bf 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -33,7 +33,6 @@
 #define FLUSH_STABLE            4       /* commit to stable storage */
 #define FLUSH_LOWPRI            8       /* low priority background flush */
 #define FLUSH_HIGHPRI           16      /* high priority memory reclaim flush */
-#define FLUSH_NOCOMMIT          32      /* Don't send the NFSv3/v4 COMMIT */
 
 #ifdef __KERNEL__
 
@@ -478,7 +477,6 @@ extern int nfs_writeback_done(struct rpc_task *, struct nfs_write_data *);
  */
 extern long nfs_sync_mapping_wait(struct address_space *, struct writeback_control *, int);
 extern int nfs_wb_all(struct inode *inode);
-extern int nfs_wb_nocommit(struct inode *inode);
 extern int nfs_wb_page(struct inode *inode, struct page* page);
 extern int nfs_wb_page_cancel(struct inode *inode, struct page* page);
 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)