scoutfs: provide cluster safe ->llseek

Without this we return -ESPIPE when a process tries to seek on a regular
file.

Signed-off-by: Mark Fasheh <mfasheh@versity.com>
[zab: adapted to new lock call]
Signed-off-by: Zach Brown <zab@zabbo.net>

kmod/src/data.c

@@ -1295,7 +1295,7 @@ const struct file_operations scoutfs_file_fops = {
 	.aio_write	= scoutfs_file_aio_write,
 	.unlocked_ioctl	= scoutfs_ioctl,
 	.fsync		= scoutfs_file_fsync,
-	.llseek		= generic_file_llseek,
+	.llseek		= scoutfs_file_llseek,
 };
 
 

kmod/src/file.c

@@ -104,3 +104,41 @@ int scoutfs_permission(struct inode *inode, int mask)
 
 	return ret;
 }
+
+loff_t scoutfs_file_llseek(struct file *file, loff_t offset, int whence)
+{
+	struct inode *inode = file->f_mapping->host;
+	struct super_block *sb = inode->i_sb;
+	struct scoutfs_lock *lock = NULL;
+	int ret = 0;
+
+	switch (whence) {
+	case SEEK_END:
+	case SEEK_DATA:
+	case SEEK_HOLE:
+		/*
+		 * These require a lock and inode refresh as they
+		 * reference i_size.
+		 *
+		 * XXX: SEEK_DATA/SEEK_HOLE can search our extent
+		 * items instead of relying on generic_file_llseek()
+		 * trickery.
+		 */
+		ret = scoutfs_lock_inode(sb, DLM_LOCK_PR,
+					 SCOUTFS_LKF_REFRESH_INODE, inode,
+					 &lock);
+	case SEEK_SET:
+	case SEEK_CUR:
+		/* No lock required, fall through to the generic helper */
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	if (ret == 0)
+		offset = generic_file_llseek(file, offset, whence);
+
+	scoutfs_unlock(sb, lock, DLM_LOCK_PR);
+
+	return ret ? ret : offset;
+}

kmod/src/file.h

@@ -6,5 +6,6 @@ ssize_t scoutfs_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
 ssize_t scoutfs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 			       unsigned long nr_segs, loff_t pos);
 int scoutfs_permission(struct inode *inode, int mask);
+loff_t scoutfs_file_llseek(struct file *file, loff_t offset, int whence);
 
 #endif	/* _SCOUTFS_FILE_H_ */