NFS: Serialise O_DIRECT i/o and truncate()

Ensure that all O_DIRECT reads and writes are complete, and prevent the
initiation of new i/o until the setattr operation that will truncate the
file is complete.

Fixes: a5864c9 ("NFS: Do not serialise O_DIRECT reads and writes")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

Author: Trond Myklebust

fs/nfs/inode.c

@@ -768,8 +768,10 @@ nfs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	trace_nfs_setattr_enter(inode);
 
 	/* Write all dirty data */
-	if (S_ISREG(inode->i_mode))
+	if (S_ISREG(inode->i_mode)) {
+		nfs_file_block_o_direct(NFS_I(inode));
 		nfs_sync_inode(inode);
+	}
 
 	fattr = nfs_alloc_fattr_with_label(NFS_SERVER(inode));
 	if (fattr == NULL) {

fs/nfs/internal.h

@@ -532,6 +532,16 @@ static inline bool nfs_file_io_is_buffered(struct nfs_inode *nfsi)
 	return test_bit(NFS_INO_ODIRECT, &nfsi->flags) == 0;
 }
 
+/* Must be called with exclusively locked inode->i_rwsem */
+static inline void nfs_file_block_o_direct(struct nfs_inode *nfsi)
+{
+	if (test_bit(NFS_INO_ODIRECT, &nfsi->flags)) {
+		clear_bit(NFS_INO_ODIRECT, &nfsi->flags);
+		inode_dio_wait(&nfsi->vfs_inode);
+	}
+}
+
+
 /* namespace.c */
 #define NFS_PATH_CANONICAL 1
 extern char *nfs_path(char **p, struct dentry *dentry,

fs/nfs/io.c

@@ -14,15 +14,6 @@
 
 #include "internal.h"
 
-/* Call with exclusively locked inode->i_rwsem */
-static void nfs_block_o_direct(struct nfs_inode *nfsi, struct inode *inode)
-{
-	if (test_bit(NFS_INO_ODIRECT, &nfsi->flags)) {
-		clear_bit(NFS_INO_ODIRECT, &nfsi->flags);
-		inode_dio_wait(inode);
-	}
-}
-
 /**
  * nfs_start_io_read - declare the file is being used for buffered reads
  * @inode: file inode
@@ -57,7 +48,7 @@ nfs_start_io_read(struct inode *inode)
 	err = down_write_killable(&inode->i_rwsem);
 	if (err)
 		return err;
-	nfs_block_o_direct(nfsi, inode);
+	nfs_file_block_o_direct(nfsi);
 	downgrade_write(&inode->i_rwsem);
 
 	return 0;
@@ -90,7 +81,7 @@ nfs_start_io_write(struct inode *inode)
 
 	err = down_write_killable(&inode->i_rwsem);
 	if (!err)
-		nfs_block_o_direct(NFS_I(inode), inode);
+		nfs_file_block_o_direct(NFS_I(inode));
 	return err;
 }