NFS: Fix another O_DIRECT race

 Ensure we call unmap_mapping_range() and sync dirty pages to disk before
 doing an NFS direct write.

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

3 files changed, 33 insertions, 42 deletions

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index b497c71384e8..079228817603 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -678,15 +678,9 @@ nfs_file_direct_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t
         if (!count)
                 goto out;
 
-        if (mapping->nrpages) {
-                retval = filemap_fdatawrite(mapping);
-                if (retval == 0)
-                        retval = nfs_wb_all(inode);
-                if (retval == 0)
-                        retval = filemap_fdatawait(mapping);
-                if (retval)
-                        goto out;
-        }
+        retval = nfs_sync_mapping(mapping);
+        if (retval)
+                goto out;
 
         retval = nfs_direct_read(inode, ctx, &iov, pos, 1);
         if (retval > 0)
@@ -764,15 +758,9 @@ nfs_file_direct_write(struct kiocb *iocb, const char __user *buf, size_t count,
         if (!count)
                 goto out;
 
-        if (mapping->nrpages) {
-                retval = filemap_fdatawrite(mapping);
-                if (retval == 0)
-                        retval = nfs_wb_all(inode);
-                if (retval == 0)
-                        retval = filemap_fdatawait(mapping);
-                if (retval)
-                        goto out;
-        }
+        retval = nfs_sync_mapping(mapping);
+        if (retval)
+                goto out;
 
         retval = nfs_direct_write(inode, ctx, &iov, pos, 1);
         if (mapping->nrpages)
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 57d3e77d97ee..eb5cd4c3bbfd 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -433,11 +433,7 @@ static int do_unlk(struct file *filp, int cmd, struct file_lock *fl)
          * Flush all pending writes before doing anything
          * with locks..
          */
-        filemap_fdatawrite(filp->f_mapping);
-        down(&inode->i_sem);
-        nfs_wb_all(inode);
-        up(&inode->i_sem);
-        filemap_fdatawait(filp->f_mapping);
+        nfs_sync_mapping(filp->f_mapping);
 
         /* NOTE: special case
          *      If we're signalled while cleaning up locks on process exit, we
@@ -465,15 +461,8 @@ static int do_setlk(struct file *filp, int cmd, struct file_lock *fl)
          * Flush all pending writes before doing anything
          * with locks..
          */
-        status = filemap_fdatawrite(filp->f_mapping);
-        if (status == 0) {
-                down(&inode->i_sem);
-                status = nfs_wb_all(inode);
-                up(&inode->i_sem);
-                if (status == 0)
-                        status = filemap_fdatawait(filp->f_mapping);
-        }
-        if (status < 0)
+        status = nfs_sync_mapping(filp->f_mapping);
+        if (status != 0)
                 goto out;
 
         lock_kernel();
@@ -497,11 +486,7 @@ static int do_setlk(struct file *filp, int cmd, struct file_lock *fl)
          * Make sure we clear the cache whenever we try to get the lock.
          * This makes locking act as a cache coherency point.
          */
-        filemap_fdatawrite(filp->f_mapping);
-        down(&inode->i_sem);
-        nfs_wb_all(inode);      /* we may have slept */
-        up(&inode->i_sem);
-        filemap_fdatawait(filp->f_mapping);
+        nfs_sync_mapping(filp->f_mapping);
         nfs_zap_caches(inode);
 out:
         rpc_clnt_sigunmask(NFS_CLIENT(inode), &oldset);
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index afd75d0463fd..432f41cd75e6 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -640,6 +640,27 @@ static int nfs_show_options(struct seq_file *m, struct vfsmount *mnt)
         return 0;
 }
 
+/**
+ * nfs_sync_mapping - helper to flush all mmapped dirty data to disk
+ */
+int nfs_sync_mapping(struct address_space *mapping)
+{
+        int ret;
+
+        if (mapping->nrpages == 0)
+                return 0;
+        unmap_mapping_range(mapping, 0, 0, 0);
+        ret = filemap_fdatawrite(mapping);
+        if (ret != 0)
+                goto out;
+        ret = filemap_fdatawait(mapping);
+        if (ret != 0)
+                goto out;
+        ret = nfs_wb_all(mapping->host);
+out:
+        return ret;
+}
+
 /*
  * Invalidate the local caches
  */
@@ -1179,11 +1200,8 @@ void nfs_revalidate_mapping(struct inode *inode, struct address_space *mapping)
         struct nfs_inode *nfsi = NFS_I(inode);
 
         if (nfsi->cache_validity & NFS_INO_INVALID_DATA) {
-                if (S_ISREG(inode->i_mode)) {
-                        if (filemap_fdatawrite(mapping) == 0)
-                                filemap_fdatawait(mapping);
-                        nfs_wb_all(inode);
-                }
+                if (S_ISREG(inode->i_mode))
+                        nfs_sync_mapping(mapping);
                 invalidate_inode_pages2(mapping);
 
                 spin_lock(&inode->i_lock);