mkfs creates a welcome file. readdir(ls) tries to list this file

mkfs-simplefs.c

@@ -4,15 +4,27 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
 
 #include "simple.h"
 
 int main(int argc, char *argv[])
 {
-	int fd;
+	int fd, nbytes;
 	ssize_t ret;
 	struct simplefs_super_block sb;
 	struct simplefs_inode root_inode;
+	struct simplefs_inode welcomefile_inode;
+
+	char welcomefile_name[] = "vanakkam";
+	char welcomefile_body[] = "Love is God. God is Love. Anbe Murugan.";
+	const uint64_t WELCOMEFILE_INODE_NUMBER = 2;
+	const uint64_t WELCOMEFILE_DATABLOCK_NUMBER = 3;
+
+	char *block_padding;
+
+	struct simplefs_dir_record record;
 
 	if (argc != 2) {
 		printf("Usage: mkfs-simplefs <device>\n");
@@ -29,8 +41,10 @@ int main(int argc, char *argv[])
 	sb.magic = SIMPLEFS_MAGIC;
 	sb.block_size = SIMPLEFS_DEFAULT_BLOCK_SIZE;
 
-	/* Only the root dir will have an inode now */
+	/* One inode for rootdirectory and another for a welcome file that we are going to create */
-	sb.inodes_count = 1;
+	sb.inodes_count = 2;
+
+	/* FIXME: Free blocks management is not implemented yet */
 	sb.free_blocks = ~0;
 
 	ret = write(fd, (char *)&sb, sizeof(sb));
@@ -48,7 +62,7 @@ int main(int argc, char *argv[])
 	root_inode.mode = S_IFDIR;
 	root_inode.inode_no = SIMPLEFS_ROOTDIR_INODE_NUMBER;
 	root_inode.data_block_number = SIMPLEFS_ROOTDIR_DATABLOCK_NUMBER;
-	root_inode.dir_children_count = 0;
+	root_inode.dir_children_count = 1;
 
 	ret = write(fd, (char *)&root_inode, sizeof(root_inode));
 
@@ -57,7 +71,65 @@ int main(int argc, char *argv[])
 		ret = -1;
 		goto exit;
 	}
-	printf("inode store written succesfully\n");
+	printf("root directory inode written succesfully\n");
+
+	welcomefile_inode.mode = S_IFREG;
+	welcomefile_inode.inode_no = WELCOMEFILE_INODE_NUMBER;
+	welcomefile_inode.data_block_number = WELCOMEFILE_DATABLOCK_NUMBER;
+	welcomefile_inode.file_size = sizeof(welcomefile_body);
+	ret = write(fd, (char *)&welcomefile_inode, sizeof(root_inode));
+
+	if (ret != sizeof(root_inode)) {
+		printf("The welcomefile inode was not written properly. Retry your mkfs\n");
+		ret = -1;
+		goto exit;
+	}
+	printf("welcomefile inode written succesfully\n");
+
+	nbytes = SIMPLEFS_DEFAULT_BLOCK_SIZE - sizeof(root_inode) - sizeof(welcomefile_inode);
+	block_padding = malloc(nbytes);
+	
+	ret = write(fd, block_padding, nbytes);
+
+	if (ret != nbytes) {
+		printf("The padding bytes are not written properly. Retry your mkfs\n");
+		ret = -1;
+		goto exit;
+	}
+	printf("inode store padding bytes (after the two inodes) written sucessfully\n");
+
+	strcpy(record.filename, welcomefile_name);
+	record.inode_no = WELCOMEFILE_INODE_NUMBER;
+	nbytes = sizeof(record);
+
+	ret = write(fd, (char *)&record, nbytes);
+	if (ret != nbytes) {
+		printf("Writing the rootdirectory datablock (name+inode_no pair for welcomefile) has failed\n");
+		ret = -1;
+		goto exit;
+	}
+	printf("root directory datablocks (name+inode_no pair for welcomefile) written succesfully\n");
+
+	nbytes = SIMPLEFS_DEFAULT_BLOCK_SIZE - sizeof(record);
+	block_padding = realloc(block_padding, nbytes);
+
+	ret = write(fd, block_padding, nbytes);
+	if (ret != nbytes) {
+		printf("Writing the padding for rootdirectory children datablock has failed\n");
+		ret = -1;
+		goto exit;
+	}
+	printf("padding after the rootdirectory children written succesfully\n");
+
+	nbytes = sizeof(welcomefile_body);
+	ret = write(fd, welcomefile_body, nbytes);
+	if (ret != nbytes) {
+		printf("Writing welcomefile body has failed\n");
+		ret = -1;
+		goto exit;
+	}
+	printf("welcomefilebody has been written succesfully\n");
+
 	ret = 0;
 
 exit:

simple.c

@@ -23,7 +23,12 @@ static int simplefs_readdir(struct file *filp, void *dirent, filldir_t filldir)
 	struct simplefs_dir_record *record;
 	int i;
 
-	printk(KERN_INFO "We are inside readdir. The pos[%lld], inode number[%lu], superblock magic [%lu]\n", pos, inode->i_ino, sb->s_magic);
+	printk(KERN_INFO "We are inside readdir. The pos[%lld], inode number[%lu], superblock magic [%lu] inodesize [%lld]\n", pos, inode->i_ino, sb->s_magic, inode->i_size);
+
+	if (pos) {
+		printk(KERN_INFO "pos seem to be non-zero which means we have already filled in all the details\n");
+		return 0;
+	}
 
 	sfs_inode = SIMPLEFS_INODE(inode);
 
@@ -38,11 +43,12 @@ static int simplefs_readdir(struct file *filp, void *dirent, filldir_t filldir)
 	for (i=0; i < sfs_inode->dir_children_count; i++) {
 		printk(KERN_INFO "Got filename: %s\n", record->filename);
 		filldir(dirent, record->filename, SIMPLEFS_FILENAME_MAXLEN, pos, record->inode_no, DT_UNKNOWN);
+		filp->f_pos += sizeof(struct simplefs_dir_record);
 		pos += sizeof(struct simplefs_dir_record);
 		record ++;
 	}
 
-	return 1;
+	return 0;
 }
 
 const struct file_operations simplefs_dir_operations = {