NFS: report and clear ENOSPC/EFBIG/EDQUOT writeback error on close() …

…file

Currently, we report and clear ENOSPC/EFBIG/EDQUOT writeback error on write(),
write() file will report unexpected error if previous writeback error have not
been cleared.

Reproducer:
        nfs server            |       nfs client
 -----------------------------|---------------------------------------------
 # No space left on server    |
 fallocate -l 100G /svr/nospc |
                              | mount -t nfs $nfs_server_ip:/ /mnt
                              |
                              | # Expected error: No space left on device
                              | dd if=/dev/zero of=/mnt/file count=1 ibs=10K
                              |
                              | # Release space on mountpoint
                              | rm /mnt/nospc
                              |
                              | # Just write 512B and report unexpected error
                              | dd if=/dev/zero of=/mnt/file count=1 ibs=10K

Fix this by clearing ENOSPC/EFBIG/EDQUOT writeback error on close file,
it will not clear other errors that are not supposed to be reported by close().

Signed-off-by: ChenXiaoSong <chenxiaosong2@huawei.com>

fs/nfs/file.c

@@ -138,7 +138,7 @@ static int
 nfs_file_flush(struct file *file, fl_owner_t id)
 {
 	struct inode	*inode = file_inode(file);
-	errseq_t since;
+	errseq_t since, error;
 
 	dprintk("NFS: flush(%pD2)\n", file);
 
@@ -149,7 +149,12 @@ nfs_file_flush(struct file *file, fl_owner_t id)
 	/* Flush writes to the server and return any errors */
 	since = filemap_sample_wb_err(file->f_mapping);
 	nfs_wb_all(inode);
-	return filemap_check_wb_err(file->f_mapping, since);
+	error = filemap_check_wb_err(file->f_mapping, since);
+
+	if (nfs_should_clear_wb_err(error))
+		file_check_and_advance_wb_err(file);
+
+	return error;
 }
 
 ssize_t
@@ -673,12 +678,7 @@ ssize_t nfs_file_write(struct kiocb *iocb, struct iov_iter *from)
 out:
 	/* Return error values */
 	error = filemap_check_wb_err(file->f_mapping, since);
-	switch (error) {
-	default:
-		break;
-	case -EDQUOT:
-	case -EFBIG:
-	case -ENOSPC:
+	if (nfs_should_clear_wb_err(error)) {
 		nfs_wb_all(inode);
 		error = file_check_and_advance_wb_err(file);
 		if (error < 0)

fs/nfs/internal.h

@@ -859,3 +859,13 @@ static inline void nfs_set_port(struct sockaddr *sap, int *port,
 
 	rpc_set_port(sap, *port);
 }
+
+static inline bool nfs_should_clear_wb_err(int error) {
+	switch (error) {
+	case -EDQUOT:
+	case -EFBIG:
+	case -ENOSPC:
+		return true;
+	}
+	return false;
+}

fs/nfs/nfs4file.c

@@ -113,7 +113,7 @@ static int
 nfs4_file_flush(struct file *file, fl_owner_t id)
 {
 	struct inode	*inode = file_inode(file);
-	errseq_t since;
+	errseq_t since, error;
 
 	dprintk("NFS: flush(%pD2)\n", file);
 
@@ -131,7 +131,12 @@ nfs4_file_flush(struct file *file, fl_owner_t id)
 	/* Flush writes to the server and return any errors */
 	since = filemap_sample_wb_err(file->f_mapping);
 	nfs_wb_all(inode);
-	return filemap_check_wb_err(file->f_mapping, since);
+	error = filemap_check_wb_err(file->f_mapping, since);
+
+	if (nfs_should_clear_wb_err(error))
+		file_check_and_advance_wb_err(file);
+
+	return error;
 }
 
 #ifdef CONFIG_NFS_V4_2