fsfreeze: added new file_start_write_killable

index d92d50f..c4f0b7b 100644
@@ -230,7 +230,9 @@ static int __do_lo_send_write(struct file *file,
 	ssize_t bw;
 	mm_segment_t old_fs = get_fs();
 
-	file_start_write(file);
+	bw = file_start_write_killable(file);
+	if (bw < 0)
+		return bw;
 	set_fs(get_ds());
 	bw = file->f_op->write(file, buf, len, &pos);
 	set_fs(old_fs);

index 2bbcacf..9e18b80 100644
@@ -915,8 +915,12 @@ static ssize_t aio_rw_vect_retry(struct kiocb *iocb, int rw, aio_rw_op *rw_op)
 	if (iocb->ki_pos < 0)
 		return -EINVAL;
 
-	if (rw == WRITE)
-		file_start_write(file);
+	if (rw == WRITE) {
+		ret = file_start_write_killable(file);
+		if (ret < 0)
+			return ret;
+	}
+
 	do {
 		ret = rw_op(iocb, &iocb->ki_iovec[iocb->ki_cur_seg],
 			    iocb->ki_nr_segs - iocb->ki_cur_seg,

index 380b798..c5708d0 100644
@@ -79,7 +79,9 @@ coda_file_write(struct file *coda_file, const char __user *buf, size_t count, lo
 		return -EINVAL;
 
 	host_inode = file_inode(host_file);
-	file_start_write(host_file);
+	ret = file_start_write_killable(host_file);
+	if (ret < 0)
+		return ret;
 	mutex_lock(&coda_inode->i_mutex);
 
 	ret = host_file->f_op->write(host_file, buf, count, ppos);

index 0343000..f0393fe 100644
@@ -439,21 +439,23 @@ ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_
 		return -EFAULT;
 
 	ret = rw_verify_area(WRITE, file, pos, count);
-	if (ret >= 0) {
-		count = ret;
-		file_start_write(file);
-		if (file->f_op->write)
-			ret = file->f_op->write(file, buf, count, pos);
-		else
-			ret = do_sync_write(file, buf, count, pos);
-		if (ret > 0) {
-			fsnotify_modify(file);
-			add_wchar(current, ret);
-		}
-		inc_syscw(current);
-		file_end_write(file);
+	if (ret < 0)
+		goto out;
+	count = ret;
+	ret = file_start_write_killable(file);
+	if (ret < 0)
+		goto out;
+	if (file->f_op->write)
+		ret = file->f_op->write(file, buf, count, pos);
+	else
+		ret = do_sync_write(file, buf, count, pos);
+	if (ret > 0) {
+		fsnotify_modify(file);
+		add_wchar(current, ret);
 	}
-
+	inc_syscw(current);
+	file_end_write(file);
+out:
 	return ret;
 }
 

@@ -721,7 +723,9 @@ static ssize_t do_readv_writev(int type, struct file *file,
 	} else {
 		fn = (io_fn_t)file->f_op->write;
 		fnv = file->f_op->aio_write;
-		file_start_write(file);
+		ret = file_start_write_killable(file);
+		if (ret < 0)
+			goto out;
 	}
 
 	if (fnv)

@@ -901,7 +905,9 @@ static ssize_t compat_do_readv_writev(int type, struct file *file,
 	} else {
 		fn = (io_fn_t)file->f_op->write;
 		fnv = file->f_op->aio_write;
-		file_start_write(file);
+		ret = file_start_write_killable(file);
+		if (ret < 0)
+			goto out;
 	}
 
 	if (fnv)

index e6b2559..b37c30e 100644
@@ -1115,7 +1115,9 @@ static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
 	else
 		splice_write = default_file_splice_write;
 
-	file_start_write(out);
+	ret = file_start_write_killable(out);
+	if (ret < 0)
+		return ret;
 	ret = splice_write(pipe, out, ppos, len, flags);
 	file_end_write(out);
 	return ret;

index 1c75053..9bd3326 100644
@@ -1404,6 +1404,16 @@ static inline void sb_start_write(struct super_block *sb)
 	__sb_start_write(sb, SB_FREEZE_WRITE, FREEZE_WAIT);
 }
 
+/**
+ * sb_start_write_killable - get write access to a superblock
+ * @sb: the super we write to
+ *
+ */
+static inline int sb_start_write_killable(struct super_block *sb)
+{
+	return __sb_start_write(sb, SB_FREEZE_WRITE, FREEZE_WAIT_KILLABLE);
+}
+
 static inline int sb_start_write_trylock(struct super_block *sb)
 {
 	return __sb_start_write(sb, SB_FREEZE_WRITE, FREEZE_NOWAIT);

@@ -2227,6 +2237,13 @@ static inline struct inode *file_inode(struct file *f)
 	return f->f_inode;
 }
 
+static inline int file_start_write_killable(struct file *file)
+{
+	if (!S_ISREG(file_inode(file)->i_mode))
+		return 1;
+	return sb_start_write_killable(file_inode(file)->i_sb);
+}
+
 static inline void file_start_write(struct file *file)
 {
 	if (!S_ISREG(file_inode(file)->i_mode))