Query File System Alignment

In SMB3 it is now possible to query the file system
alignment info, and the preferred (for performance)
sector size and whether the underlying disk
has no seek penalty (like SSD).

Query this information at mount time for SMB3,
and make it visible in /proc/fs/cifs/DebugData
for debugging purposes.

This alignment information and preferred sector
size info will be helpful for the copy offload
patches to setup the right chunks in the CopyChunk
requests.   Presumably the knowledge that the
underlying disk is SSD could also help us
make better readahead and writebehind
decisions (something to look at in the future).

Signed-off-by: Steve French <smfrench@gmail.com>

fs/cifs/smb2pdu.c

@@ -2373,8 +2373,11 @@ SMB2_QFS_attr(const unsigned int xid, struct cifs_tcon *tcon,
 	} else if (level == FS_ATTRIBUTE_INFORMATION) {
 		max_len = sizeof(FILE_SYSTEM_ATTRIBUTE_INFO);
 		min_len = MIN_FS_ATTR_INFO_SIZE;
+	} else if (level == FS_SECTOR_SIZE_INFORMATION) {
+		max_len = sizeof(struct smb3_fs_ss_info);
+		min_len = sizeof(struct smb3_fs_ss_info);
 	} else {
-		cifs_dbg(FYI, "Invalid qfsinfo level %d", level);
+		cifs_dbg(FYI, "Invalid qfsinfo level %d\n", level);
 		return -EINVAL;
 	}
 
@@ -2403,6 +2406,13 @@ SMB2_QFS_attr(const unsigned int xid, struct cifs_tcon *tcon,
 	else if (level == FS_DEVICE_INFORMATION)
 		memcpy(&tcon->fsDevInfo, 4 /* RFC1001 len */ + offset
 			+ (char *)&rsp->hdr, sizeof(FILE_SYSTEM_DEVICE_INFO));
+	else if (level == FS_SECTOR_SIZE_INFORMATION) {
+		struct smb3_fs_ss_info *ss_info = (struct smb3_fs_ss_info *)
+			(4 /* RFC1001 len */ + offset + (char *)&rsp->hdr);
+		tcon->ss_flags = le32_to_cpu(ss_info->Flags);
+		tcon->perf_sector_size =
+			le32_to_cpu(ss_info->PhysicalBytesPerSectorForPerf);
+	}
 
 qfsattr_exit:
 	free_rsp_buf(resp_buftype, iov.iov_base);