X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=fs%2Fbattfs.c;h=fd8fe1c6761b6cabdbb5c65a4eac8bba894c05b3;hb=1ab5fa0763879ab997884c8bc88631b69205a191;hp=55329677b56c9cf2812e1c66a62b8ec98ca29563;hpb=2b5d8bc0533385e11a44383cf8d86c895f8f946c;p=bertos.git

diff --git a/fs/battfs.c b/fs/battfs.c
index 55329677..fd8fe1c6 100644
--- a/fs/battfs.c
+++ b/fs/battfs.c
@@ -53,38 +53,43 @@
  */
 INLINE void battfs_to_disk(struct BattFsPageHeader *hdr, uint8_t *buf)
 {
-	STATIC_ASSERT(BATTFS_HEADER_LEN == 13);
+	STATIC_ASSERT(BATTFS_HEADER_LEN == 12);
 	buf[0] = hdr->inode;
 
-	buf[1] = hdr->seq;
+	buf[1] = hdr->fill;
+	buf[2] = hdr->fill >> 8;
 
-	buf[2] = hdr->fill;
-	buf[3] = hdr->fill >> 8;
-
-	buf[4] = hdr->pgoff;
-	buf[5] = hdr->pgoff >> 8;
+	buf[3] = hdr->pgoff;
+	buf[4] = hdr->pgoff >> 8;
 
 	/*
 	 * Mark is at least 1 bit longer than page address.
 	 * Needed to take care of wraparonds.
 	 */
-	buf[6] = hdr->mark;
-	buf[7] = hdr->mark >> 8;
-	buf[8] = hdr->mark >> 16;
+	buf[5] = hdr->mark;
+	buf[6] = hdr->mark >> 8;
+
+	/*
+	 * First bit used by mark, last 2 bits used by seq.
+	 * Since only 2 pages with the same inode and pgoff
+	 * can exist at the same time, 2 bit for seq are enough.
+	 * Unused bits are set to 1.
+	 */
+	buf[7] = ((hdr->mark >> 16) & 0x01) | (hdr->seq << 6) | ~(BV(7) | BV(6) | BV(0));
 
 	/*
 	 * This field must be the before the last one!
 	 */
-	buf[9] = hdr->fcs_free;
-	buf[10] = hdr->fcs_free >> 8;
+	buf[8] = hdr->fcs_free;
+	buf[9] = hdr->fcs_free >> 8;
 
 	/*
 	 * This field must be the last one!
 	 * This is needed because if the page is only partially
 	 * written, we can use this to detect it.
 	 */
-	buf[11] = hdr->fcs;
-	buf[12] = hdr->fcs >> 8;
+	buf[10] = hdr->fcs;
+	buf[11] = hdr->fcs >> 8;
 }
 
 /**
@@ -93,14 +98,14 @@ INLINE void battfs_to_disk(struct BattFsPageHeader *hdr, uint8_t *buf)
  */
 INLINE void disk_to_battfs(uint8_t *buf, struct BattFsPageHeader *hdr)
 {
-	STATIC_ASSERT(BATTFS_HEADER_LEN == 13);
+	STATIC_ASSERT(BATTFS_HEADER_LEN == 12);
 	hdr->inode = buf[0];
-	hdr->seq = buf[1];
-	hdr->fill = buf[3] << 8 | buf[2];
-	hdr->pgoff = buf[5] << 8 | buf[4];
-	hdr->mark = (mark_t)buf[8] << 16 | buf[7] << 8 | buf[6];
-	hdr->fcs_free = buf[10] << 8 | buf[9];
-	hdr->fcs = buf[12] << 8 | buf[11];
+	hdr->fill = buf[2] << 8 | buf[1];
+	hdr->pgoff = buf[4] << 8 | buf[3];
+	hdr->mark = (mark_t)(buf[7] & 0x01) << 16 | buf[6] << 8 | buf[5];
+	hdr->seq = buf[7] >> 6;
+	hdr->fcs_free = buf[9] << 8 | buf[8];
+	hdr->fcs = buf[11] << 8 | buf[10];
 }
 
 /**
@@ -114,7 +119,7 @@ static fcs_t computeFcs(struct BattFsPageHeader *hdr)
 	battfs_to_disk(hdr, buf);
 	rotating_init(&cks);
 	/* fcs is at the end of whole header */
-	rotating_update(buf,BATTFS_HEADER_LEN - sizeof(fcs_t), &cks);
+	rotating_update(buf, BATTFS_HEADER_LEN - sizeof(fcs_t), &cks);
 	return cks;
 }
 
@@ -129,7 +134,7 @@ static fcs_t computeFcsFree(struct BattFsPageHeader *hdr)
 	battfs_to_disk(hdr, buf);
 	rotating_init(&cks);
 	/* fcs_free is just before fcs of whole header */
-	rotating_update(buf,BATTFS_HEADER_LEN - 2 * sizeof(fcs_t), &cks);
+	rotating_update(buf, BATTFS_HEADER_LEN - 2 * sizeof(fcs_t), &cks);
 	return cks;
 }
 
@@ -144,10 +149,10 @@ static bool battfs_readHeader(struct BattFsSuper *disk, pgcnt_t page, struct Bat
 	uint8_t buf[BATTFS_HEADER_LEN];
 	/*
 	 * Read header from disk.
-	 * header is actually a footer, and so
+	 * Header is actually a footer, and so
 	 * resides at page end.
 	 */
-	if (disk->read(disk, page, disk->page_size - BATTFS_HEADER_LEN - 1, buf, BATTFS_HEADER_LEN)
+	if (disk->read(disk, page, disk->page_size - BATTFS_HEADER_LEN, buf, BATTFS_HEADER_LEN)
 	    != BATTFS_HEADER_LEN)
 	{
 		TRACEMSG("Error: page[%d]\n", page);
@@ -160,6 +165,32 @@ static bool battfs_readHeader(struct BattFsSuper *disk, pgcnt_t page, struct Bat
 	return true;
 }
 
+/**
+ * Write header of page \a page.
+ * \return true on success, false otherwise.
+ * \note \a hdr is dirtyed even on errors.
+ */
+static bool battfs_writeHeader(struct BattFsSuper *disk, pgcnt_t page, struct BattFsPageHeader *hdr)
+{
+	uint8_t buf[BATTFS_HEADER_LEN];
+
+	/* Fill buffer */
+	battfs_to_disk(hdr, buf);
+
+	/*
+	 * write header to disk.
+	 * Header is actually a footer, and so
+	 * resides at page end.
+	 */
+	if (disk->write(disk, page, disk->page_size - BATTFS_HEADER_LEN, buf, BATTFS_HEADER_LEN)
+	    != BATTFS_HEADER_LEN)
+	{
+		TRACEMSG("Error: page[%d]\n", page);
+		return false;
+	}
+	return true;
+}
+
 /**
  * Count the number of pages from
  * inode 0 to \a inode in \a filelen_table.
@@ -181,7 +212,7 @@ static pgcnt_t countPages(pgoff_t *filelen_table, inode_t inode)
 static void movePages(struct BattFsSuper *disk, pgcnt_t src, int offset)
 {
 	pgcnt_t dst = src + offset;
-	memmove(&disk->page_array[dst], &disk->page_array[src], disk->page_count - MAX(dst, src) * sizeof(pgcnt_t));
+	memmove(&disk->page_array[dst], &disk->page_array[src], (disk->page_count - MAX(dst, src)) * sizeof(pgcnt_t));
 	
 	if (offset < 0)
 	{
@@ -192,18 +223,18 @@ static void movePages(struct BattFsSuper *disk, pgcnt_t src, int offset)
 }
 
 /**
- * Insert \a page into page allocation array of \a disk, using \a filelen_table and
- * \a free_number to compute position.
+ * Insert \a page into page allocation array of \a disk,
+ * using  \a mark to compute position.
  */
-static void insertFreePage(struct BattFsSuper *disk, pgoff_t *filelen_table, mark_t mark, pgcnt_t page)
+static void insertFreePage(struct BattFsSuper *disk, mark_t mark, pgcnt_t page)
 {
-	ASSERT(mark >= disk->free_min);
-	ASSERT(mark <= disk->free_max);
+	ASSERT(mark - disk->free_start < disk->free_next - disk->free_start);
+
+	pgcnt_t free_pos = disk->page_count - disk->free_next + mark;
+	ASSERT(free_pos < disk->page_count);
 
-	pgcnt_t free_pos = countPages(filelen_table, BATTFS_MAX_FILES - 1);
-	free_pos += mark - disk->free_min;
-	TRACEMSG("mark:%d, page:%d, free_min:%d, free_max:%d, free_pos:%d\n",
-		mark, page, disk->free_min, disk->free_max, free_pos);
+	TRACEMSG("mark:%u, page:%u, free_start:%u, free_next:%u, free_pos:%u\n",
+		mark, page, disk->free_start, disk->free_next, free_pos);
 
 	ASSERT(disk->page_array[free_pos] == PAGE_UNSET_SENTINEL);
 	disk->page_array[free_pos] = page;
@@ -211,66 +242,136 @@ static void insertFreePage(struct BattFsSuper *disk, pgoff_t *filelen_table, mar
 
 /**
  * Mark \a page of \a disk as free.
- * \note free_max of \a disk is increased by 1 and is used as
- *       \a page free marker.
+ * \note free_next of \a disk is used as \a page free marker
+ * and is increased by 1.
  */
 static bool battfs_markFree(struct BattFsSuper *disk, struct BattFsPageHeader *hdr, pgcnt_t page)
 {
 	uint8_t buf[BATTFS_HEADER_LEN];
 
-	hdr->mark = disk->free_max++;
+	hdr->mark = disk->free_next;
 	hdr->fcs_free = computeFcsFree(hdr);
 	battfs_to_disk(hdr, buf);
 
-	if (!disk->write(disk, page, disk->page_size - BATTFS_HEADER_LEN - 1, buf, BATTFS_HEADER_LEN))
+	if (!disk->write(disk, page, disk->page_size - BATTFS_HEADER_LEN, buf, BATTFS_HEADER_LEN))
 	{
 		TRACEMSG("error marking page [%d]\n", page);
 		return false;
 	}
 	else
+	{
+		disk->free_next++;
 		return true;
+	}
 }
 
-
 /**
- * Initialize and mount disk described by
- * \a d.
- * \return false on errors, true otherwise.
+ * Determine free_start and free_next blocks for \a disk
+ * using \a minl, \a maxl, \a minh, \a maxh.
+ *
+ * Mark_t is a type that has at least 1 bit more than
+ * pgaddr_t. So all free blocks can be numbered using
+ * at most half numbers of a mark_t type.
+ * The free blocks algorithm increments by 1 the disk->free_next
+ * every time a page becomes free. So the free block sequence is
+ * guaranteed to be countiguous.
+ * Only wrap arounds may happen, but due to half size sequence limitation,
+ * there are only 4 possible situations:
+ *
+ * \verbatim
+ *    |------lower half------|-------upper half-------|
+ *
+ * 1) |------minl*****maxl---|------------------------|
+ * 2) |------minl********maxl|minh******maxh----------|
+ * 3) |----------------------|----minh*******maxh-----|
+ * 4) |minl******maxl--------|------------minh****maxh|
+ * \endverbatim
+ *
+ * Situations 1 and 3 are easy to detect, while 2 and 4 require more care.
  */
-bool battfs_init(struct BattFsSuper *disk)
+static void findFreeStartNext(struct BattFsSuper *disk, mark_t minl, mark_t maxl, mark_t minh, mark_t maxh)
 {
-	BattFsPageHeader hdr;
-	pgoff_t filelen_table[BATTFS_MAX_FILES];
-	mark_t minl, maxl, minh, maxh;
+	/* Determine free_start & free_next */
+	if (maxl >= minl)
+	{
+		/* Valid interval found in lower half */
+		if (maxh >= minh)
+		{
+			/* Valid interval also found in upper half */
+			if (maxl == minh - 1)
+			{
+				/* Interval starts in lower half and ends in upper */
+				disk->free_start = minl;
+				disk->free_next = maxh;
+			}
+			else
+			{
+				/* Interval starts in upper half and ends in lower */
+				ASSERT(minl == 0);
+				ASSERT(maxh == (MAX_PAGE_ADDR | MARK_HALF_SIZE));
 
-	/* Sanity checks */
-	ASSERT(disk->open);
-	ASSERT(disk->read);
-	ASSERT(disk->write);
-	ASSERT(disk->erase);
-	ASSERT(disk->close);
-	ASSERT(disk->page_size);
-	ASSERT(disk->page_count);
-	ASSERT(disk->page_count < PAGE_UNSET_SENTINEL - 1);
-	ASSERT(disk->page_array);
-	
-	/* Init disk device */
-	if (!disk->open(disk))
+				disk->free_start = minh;
+				disk->free_next = maxl;
+			}
+		}
+		else
+		{
+			/*
+			 * Upper interval is invalid.
+			 * Use lower values.
+			 */
+			
+			disk->free_start = minl;
+			disk->free_next = maxl;
+		}
+	}
+	else if (maxh >= minh)
 	{
-		TRACEMSG("open error\n");
-		return false;
+		/*
+		 * Lower interval is invalid.
+		 * Use upper values.
+		 */
+		disk->free_start = minh;
+		disk->free_next = maxh;
+	}
+	else
+	{
+		/*
+		 * No valid interval found.
+		 * Hopefully the disk is brand new (or full).
+		 */
+		TRACEMSG("No valid marked free block found, new disk or disk full\n");
+		disk->free_start = 0;
+		disk->free_next = -1; //to be increased later
 	}
 
-	memset(filelen_table, 0, BATTFS_MAX_FILES * sizeof(pgoff_t));
+	/* free_next should contain the first usable address */
+	disk->free_next++;
+
+	TRACEMSG("Free markers:\n minl %u\n maxl %u\n minh %u\n maxh %u\n free_start %u\n free_next %u\n",
+		minl, maxl, minh, maxh, disk->free_start, disk->free_next);
+}
 
-	/* Initialize min and max counters to keep trace od fre blocks */
+/**
+ * Count number of pages per file on \a disk.
+ * This information is registered in \a filelen_table.
+ * Array index represent file inode, while value contained
+ * is the number of pages used by that file.
+ *
+ * \return true if ok, false on disk read errors.
+ * \note The whole disk is scanned once.
+ */
+static bool countDiskFilePages(struct BattFsSuper *disk, pgoff_t *filelen_table)
+{
+	BattFsPageHeader hdr;
+	mark_t minl, maxl, minh, maxh;
+
+	/* Initialize min and max counters to keep trace od free blocks */
 	minl = MAX_PAGE_ADDR;
 	maxl = 0;
 	minh = MAX_PAGE_ADDR | MARK_HALF_SIZE;
 	maxh = 0 | MARK_HALF_SIZE;
 
-	disk->free_bytes =0;
-	disk->disk_size = (disk_size_t)(disk->page_size - BATTFS_HEADER_LEN) * disk->page_count;
 
 	/* Count the number of disk page per file */
 	for (pgcnt_t page = 0; page < disk->page_count; page++)
@@ -281,12 +382,13 @@ bool battfs_init(struct BattFsSuper *disk)
 		/* Check header FCS */
 		if (hdr.fcs == computeFcs(&hdr))
 		{
-			/* Page is valid and is owned by a file */
-			filelen_table[hdr.inode]++;
-
 			ASSERT(hdr.mark == MARK_PAGE_VALID);
 			ASSERT(hdr.fcs_free == FCS_FREE_VALID);
 			ASSERT(hdr.fill <= disk->page_size - BATTFS_HEADER_LEN);
+
+			/* Page is valid and is owned by a file */
+			filelen_table[hdr.inode]++;
+
 			/* Keep trace of free space */
 			disk->free_bytes += disk->page_size - BATTFS_HEADER_LEN - hdr.fill;
 		}
@@ -295,7 +397,7 @@ bool battfs_init(struct BattFsSuper *disk)
 			/* Increase free space */
 			disk->free_bytes += disk->page_size - BATTFS_HEADER_LEN;
 			
-			/* Check if page is free */
+			/* Check if page is marked free */
 			if (hdr.fcs_free == computeFcsFree(&hdr))
 			{
 				/*
@@ -310,61 +412,35 @@ bool battfs_init(struct BattFsSuper *disk)
 				else
 				{
 					minh = MIN(minh, hdr.mark);
-					maxl = MAX(maxl, hdr.mark);
+					maxh = MAX(maxh, hdr.mark);
 				}
 			}
 			else
 				TRACEMSG("page [%d] invalid, keeping as free\n", page);
 		}
 	}
+	findFreeStartNext(disk, minl, maxl, minh, maxh);
+	return true;
+}
 
-	/* Once here, we have filelen_table filled with file lengths */
-
-	/* Fill page array with sentinel */
-	for (pgcnt_t page = 0; page < disk->page_count; page++)
-		disk->page_array[page] = PAGE_UNSET_SENTINEL;
-
-	/* Determine free_min & free_max */
-	if (maxl >= minl)
-	{
-		if (maxh >= minh)
-		{
-			if (maxl == minh - 1)
-			{
-				disk->free_min = minl;
-				disk->free_max = maxh;
-			}
-			else
-			{
-				ASSERT(minl == 0);
-				ASSERT(maxh == (MAX_PAGE_ADDR | MARK_HALF_SIZE));
-
-				disk->free_min = minh;
-				disk->free_max = maxl;
-			}
-		}
-		else
-		{
-			disk->free_min = minl;
-			disk->free_max = maxl;
-		}
-	}
-	else if (maxh >= minh)
-	{
-		disk->free_min = minh;
-		disk->free_max = maxh;
-	}
-	else
-	{
-		TRACEMSG("No valid marked free block found\n");
-		disk->free_min = 0;
-		#warning Check this!
-		disk->free_max = -1;
-	}
-	TRACEMSG("Free markers:\n minl %u\n maxl %u\n minh %u\n maxh %u\n free_min %u\n free_max %u\n",
-		minl, maxl, minh, maxh, disk->free_min, disk->free_max);
-
-
+/**
+ * Fill page allocation array of \a disk
+ * using file lenghts in \a filelen_table.
+ *
+ * The page allocation array is an array containings all file infos.
+ * Is ordered by file, and within each file is ordered by page offset
+ * inside file.
+ * e.g. : at page array[0] you will find page address of the first page
+ * of the first file (if present).
+ * Free blocks are allocated after the last file, starting from invalid ones
+ * and continuing with the marked free ones.
+ *
+ * \return true if ok, false on disk read errors.
+ * \note The whole disk is scanned once.
+ */
+static bool fillPageArray(struct BattFsSuper *disk, pgoff_t *filelen_table)
+{
+	BattFsPageHeader hdr;
 	/* Fill page allocation array */
 	for (pgcnt_t page = 0; page < disk->page_count; page++)
 	{
@@ -405,9 +481,8 @@ bool battfs_init(struct BattFsSuper *disk)
 				pgcnt_t new_page, old_page;
 				fill_t old_fill;
 
-				/* Fancy check to handle seq wraparound */
-				#define HALF_SEQ (1 << ((sizeof(seq_t) * CPU_BITS_PER_CHAR) - 1))
-				if ((hdr.seq - hdr_old.seq) < HALF_SEQ)
+				/* Fancy check to handle seq wraparound (2 bits only) */
+				if (((hdr.seq - hdr_old.seq) & 0x03) < 2)
 				{
 					/* Current header is newer than the previuos one */
 					old_page = disk->page_array[array_pos];
@@ -440,22 +515,312 @@ bool battfs_init(struct BattFsSuper *disk)
 				if (!battfs_markFree(disk, &hdr, old_page))
 					return false;
 
-				insertFreePage(disk, filelen_table, disk->free_max, old_page);
+				insertFreePage(disk, hdr.mark, old_page);
 			}
 		}
 		else
 		{
 			/* Check if page is free */
 			if (hdr.fcs_free != computeFcsFree(&hdr))
-				/* Page is not a valid marked page, insert at the end of list */
-				hdr.mark = ++disk->free_max;
+				/* Page is not a valid marked page, insert at list beginning */
+				hdr.mark = --disk->free_start;
 
-			insertFreePage(disk, filelen_table, hdr.mark, page);
+			insertFreePage(disk, hdr.mark, page);
 		}
 	}
+	return true;
+}
+
+/**
+ * Initialize and mount disk described by
+ * \a disk.
+ * \return false on errors, true otherwise.
+ */
+bool battfs_init(struct BattFsSuper *disk)
+{
+	pgoff_t filelen_table[BATTFS_MAX_FILES];
+
+	/* Sanity check */
+	ASSERT(disk->open);
+
+	/* Init disk device */
+	if (!disk->open(disk))
+	{
+		TRACEMSG("open error\n");
+		return false;
+	}
+
+	/* Disk open must set all of these */
+	ASSERT(disk->read);
+	ASSERT(disk->write);
+	ASSERT(disk->erase);
+	ASSERT(disk->close);
+	ASSERT(disk->page_size);
+	ASSERT(disk->page_count);
+	ASSERT(disk->page_count < PAGE_UNSET_SENTINEL - 1);
+	ASSERT(disk->page_array);
+
+	memset(filelen_table, 0, BATTFS_MAX_FILES * sizeof(pgoff_t));
+
+	disk->free_bytes = 0;
+	disk->disk_size = (disk_size_t)(disk->page_size - BATTFS_HEADER_LEN) * disk->page_count;
+
+	/* Count pages per file */
+	if (!countDiskFilePages(disk, filelen_table))
+	{
+		TRACEMSG("error counting file pages\n");
+		return false;
+	}
+
+	/* Once here, we have filelen_table filled with file lengths */
 
-	#warning Test me!	
+	/* Fill page array with sentinel */
+	for (pgcnt_t page = 0; page < disk->page_count; page++)
+		disk->page_array[page] = PAGE_UNSET_SENTINEL;
+
+	/* Fill page allocation array using filelen_table */
+	if (!fillPageArray(disk, filelen_table))
+	{
+		TRACEMSG("error filling page array\n");
+		return false;
+	}
+
+	/* Init list for opened files. */
+	LIST_INIT(&disk->file_opened_list);
 	return true;	
 }
 
+/**
+ * Flush file \a fd.
+ * \return 0 if ok, EOF on errors.
+ */
+static int battfs_flush(struct KFile *fd)
+{
+	(void)fd;
+	#warning TODO
+	return 0;
+}
+
+/**
+ * Close file \a fd.
+ * \return 0 if ok, EOF on errors.
+ */
+static int battfs_fileclose(struct KFile *fd)
+{
+	KFileBattFs *fdb = KFILEBATTFS(fd);
+
+	battfs_flush(fd);
+	REMOVE(&fdb->link);
+	return 0;
+}
+
+/**
+ * Read from file \a fd \a size bytes in \a buf.
+ * \return The number of bytes read.
+ */
+static size_t battfs_read(struct KFile *fd, void *_buf, size_t size)
+{
+	KFileBattFs *fdb = KFILEBATTFS(fd);
+	uint8_t *buf = (uint8_t *)_buf;
+
+	size_t total_read = 0;
+	pgoff_t pg_offset;
+	pgaddr_t addr_offset;
+	pgaddr_t read_len;
+
+	size = MIN(size, fd->size - fd->seek_pos);
+
+	while (size)
+	{
+		pg_offset = fd->seek_pos / (fdb->disk->page_size - BATTFS_HEADER_LEN);
+		addr_offset = fd->seek_pos % (fdb->disk->page_size - BATTFS_HEADER_LEN);
+		read_len = MIN(size, (size_t)(fdb->disk->page_size - BATTFS_HEADER_LEN - addr_offset));
 
+		/* Read from disk */
+		if (fdb->disk->read(fdb->disk, fdb->start[pg_offset], addr_offset, buf, read_len) != read_len)
+		{
+			#warning TODO set error?
+		}
+
+		size -= read_len;
+		fd->seek_pos += read_len;
+		total_read += read_len;
+		buf += read_len;
+	}
+	return total_read;
+}
+
+
+/**
+ * Search file \a inode in \a disk using a binary search.
+ * \return pointer to file start in disk->page_array
+ * if file exists, NULL otherwise.
+ */
+static pgcnt_t *findFile(BattFsSuper *disk, inode_t inode)
+{
+	BattFsPageHeader hdr;
+	pgcnt_t first = 0, page, last = disk->page_count -1;
+	fcs_t fcs;
+
+	while (first <= last)
+	{
+       		page = (first + last) / 2;
+
+		if (!battfs_readHeader(disk, disk->page_array[page], &hdr))
+			return NULL;
+
+		fcs = computeFcs(&hdr);
+		if (hdr.fcs == fcs && hdr.inode == inode)
+           		return (&disk->page_array[page]) - hdr.pgoff;
+       		else if (hdr.fcs == fcs && hdr.inode < inode)
+           		first = page + 1;
+       		else
+           		last = page - 1;
+	}
+
+	return NULL;
+}
+
+/**
+ * \return true if file \a inode exists on \a disk, false otherwise.
+ */
+bool battfs_fileExists(BattFsSuper *disk, inode_t inode)
+{
+	return findFile(disk, inode) != NULL;
+}
+
+/**
+ * Count size of file \a inode on \a disk, starting at pointer \a start
+ * in disk->page_array. Size is written in \a size.
+ * \return true if all s ok, false on disk read errors.
+ */
+static bool countFileSize(BattFsSuper *disk, pgcnt_t *start, inode_t inode, file_size_t *size)
+{
+	*size = 0;
+	BattFsPageHeader hdr;
+
+	for (;;)
+	{
+		if (!battfs_readHeader(disk, *start++, &hdr))
+			return false;
+		if (hdr.fcs == computeFcs(&hdr) && hdr.inode == inode)
+			*size += hdr.fill;
+		else
+			return true;
+	}
+}
+
+/**
+ * Open file \a inode from \a disk in \a mode.
+ * File context is stored in \a fd.
+ * \return true if ok, false otherwise.
+ */
+bool battfs_fileopen(BattFsSuper *disk, KFileBattFs *fd, inode_t inode, filemode_t mode)
+{
+	Node *n;
+
+	memset(fd, 0, sizeof(*fd));
+
+	/* Search file start point in disk page array */
+	fd->start = findFile(disk, inode);
+	if (fd->start == NULL)
+	{
+		if (!(mode & BATTFS_CREATE))
+			return false;
+
+		/* File does not exist, create it */
+		BattFsPageHeader hdr;
+		hdr.inode = inode;
+		hdr.seq = 0;
+		hdr.fill = 0;
+		hdr.pgoff = 0;
+		hdr.mark = MARK_PAGE_VALID;
+		hdr.fcs_free = FCS_FREE_VALID;
+		hdr.fcs = computeFcs(&hdr);
+		#warning TODO: get a free block and write on disk!
+	}
+
+	/* Fill file size */
+	if (!countFileSize(disk, fd->start, inode, &fd->fd.size))
+		return false;
+
+	/* Reset seek position */
+	fd->fd.seek_pos = 0;
+
+	/* Insert file handle in list, ordered by inode, ascending. */
+	FOREACH_NODE(n, &disk->file_opened_list)
+	{
+		KFileBattFs *file = containerof(n, KFileBattFs, link);
+		if (file->inode >= inode)
+			break;
+	}
+	INSERT_BEFORE(&fd->link, n);
+
+	/* Fill in data */
+	fd->inode = inode;
+	fd->mode = mode;
+	fd->disk = disk;
+
+	fd->fd.close = battfs_fileclose;
+	fd->fd.flush = battfs_flush;
+	fd->fd.read = battfs_read;
+	fd->fd.reopen = kfile_genericReopen;
+	fd->fd.seek = kfile_genericSeek;
+	
+#warning TODO battfs_write, battfs_error, battfs_clearerr
+#if 0
+	fd->fd.write = battfs_write;
+	fd->fd.error = battfs_error;
+	fd->fd.clearerr = battfs_clearerr;
+#endif
+
+	DB(fd->fd._type = KFT_BATTFS);
+
+	return true;
+}
+
+/**
+ * Close \a disk.
+ */
+bool battfs_close(struct BattFsSuper *disk)
+{
+	Node *n;
+	int res = 0;
+
+	/* Close all open files */
+	FOREACH_NODE(n, &disk->file_opened_list)
+	{
+		KFileBattFs *file = containerof(n, KFileBattFs, link);
+		res += battfs_fileclose(&file->fd);
+	}
+
+	/* Close disk */
+	return disk->close(disk) && (res == 0);
+}
+
+
+bool battfs_writeTestBlock(struct BattFsSuper *disk, pgcnt_t page, inode_t inode, seq_t seq, fill_t fill, pgoff_t pgoff, mark_t mark)
+{
+	BattFsPageHeader hdr;
+
+	hdr.inode = inode;
+	hdr.seq = seq;
+	hdr.fill = fill;
+	hdr.pgoff = pgoff;
+	hdr.mark = MARK_PAGE_VALID;
+	hdr.fcs_free = FCS_FREE_VALID;
+	hdr.fcs = computeFcs(&hdr);
+	if (mark != MARK_PAGE_VALID)
+	{
+		hdr.mark = mark;
+		hdr.fcs_free = computeFcsFree(&hdr);
+	}
+
+	if (!battfs_writeHeader(disk, page, &hdr))
+	{
+		TRACEMSG("error writing hdr\n");
+		return false;
+	}
+
+	return true;
+}