#include <string.h> /* memset, memmove */
+
/**
- * Convert mark_t from cpu endianess to filesystem endianness.
+ * Convert from memory representation to disk structure.
* \note filesystem is in little-endian format.
*/
-INLINE mark_t cpu_to_mark_t(mark_t mark)
+INLINE void battfs_to_disk(struct BattFsPageHeader *hdr, uint8_t *buf)
{
- STATIC_ASSERT(sizeof(mark_t) == 2);
- return cpu_to_le16(mark);
+ STATIC_ASSERT(BATTFS_HEADER_LEN == 12);
+ buf[0] = hdr->inode;
+
+ buf[1] = hdr->fill;
+ buf[2] = hdr->fill >> 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[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.
+ */
+ buf[7] = ((hdr->mark >> 16) & 0x01) | (hdr->seq << 6);
+
+ /*
+ * This field must be the before the last one!
+ */
+ 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[10] = hdr->fcs;
+ buf[11] = hdr->fcs >> 8;
}
/**
- * Convert mark_t from filesystem endianness to cpu endianess.
+ * Convert from disk structure to memory representation.
* \note filesystem is in little-endian format.
*/
-INLINE mark_t mark_t_to_cpu(mark_t mark)
+INLINE void disk_to_battfs(uint8_t *buf, struct BattFsPageHeader *hdr)
{
- STATIC_ASSERT(sizeof(mark_t) == 2);
- return le16_to_cpu(mark);
+ STATIC_ASSERT(BATTFS_HEADER_LEN == 12);
+ hdr->inode = buf[0];
+ 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];
}
/**
- * Convert from cpu endianess to filesystem endianness.
- * \note filesystem is in little-endian format.
+ * Compute the fcs of the header.
*/
-INLINE void cpu_to_battfs(struct BattFsPageHeader *hdr)
+static fcs_t computeFcs(struct BattFsPageHeader *hdr)
{
- STATIC_ASSERT(sizeof(hdr->inode) == 1);
- STATIC_ASSERT(sizeof(hdr->seq) == 1);
-
- hdr->mark = cpu_to_mark_t(hdr->mark);
-
- STATIC_ASSERT(sizeof(hdr->fill) == 2);
- hdr->fill = cpu_to_le16(hdr->fill);
-
- STATIC_ASSERT(sizeof(hdr->pgoff) == 2);
- hdr->pgoff = cpu_to_le16(hdr->pgoff);
-
- STATIC_ASSERT(sizeof(hdr->fcs) == 2);
- hdr->fcs = cpu_to_le16(hdr->fcs);
-
- STATIC_ASSERT(sizeof(hdr->rfu) == 2);
- hdr->rfu = cpu_to_le16(hdr->rfu);
+ uint8_t buf[BATTFS_HEADER_LEN];
+ fcs_t cks;
+
+ 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);
+ return cks;
}
-
/**
- * Convert from filesystem endianness to cpu endianess.
- * \note filesystem is in little-endian format.
+ * Compute the fcs of the header marked as free.
*/
-INLINE void battfs_to_cpu(struct BattFsPageHeader *hdr)
+static fcs_t computeFcsFree(struct BattFsPageHeader *hdr)
{
- STATIC_ASSERT(sizeof(hdr->inode) == 1);
- STATIC_ASSERT(sizeof(hdr->seq) == 1);
-
- hdr->mark = mark_t_to_cpu(hdr->mark);
-
- STATIC_ASSERT(sizeof(hdr->fill) == 2);
- hdr->fill = le16_to_cpu(hdr->fill);
-
- STATIC_ASSERT(sizeof(hdr->pgoff) == 2);
- hdr->pgoff = le16_to_cpu(hdr->pgoff);
-
- STATIC_ASSERT(sizeof(hdr->fcs) == 2);
- hdr->fcs = le16_to_cpu(hdr->fcs);
-
- STATIC_ASSERT(sizeof(hdr->rfu) == 2);
- hdr->rfu = le16_to_cpu(hdr->rfu);
+ uint8_t buf[BATTFS_HEADER_LEN];
+ fcs_t cks;
+
+ 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);
+ return cks;
}
*/
static bool battfs_readHeader(struct BattFsSuper *disk, pgcnt_t page, struct BattFsPageHeader *hdr)
{
+ 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 - sizeof(BattFsPageHeader), hdr, sizeof(BattFsPageHeader))
- != sizeof(BattFsPageHeader))
+ if (disk->read(disk, page, disk->page_size - BATTFS_HEADER_LEN - 1, buf, BATTFS_HEADER_LEN)
+ != BATTFS_HEADER_LEN)
{
TRACEMSG("Error: page[%d]\n", page);
return false;
}
- /* Fix endianess */
- battfs_to_cpu(hdr);
+ /* Fill header */
+ disk_to_battfs(buf, hdr);
return true;
}
}
/**
- * 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 free_number, pgcnt_t page)
+static void insertFreePage(struct BattFsSuper *disk, mark_t mark, pgcnt_t page)
{
- ASSERT(mark >= disk->min_free);
- ASSERT(mark <= disk->max_free);
+ 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);
+
+ 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);
- pgcnt_t free_pos = countPages(filelen_table, BATTFS_MAX_FILES - 1);
- free_pos += free_number - disk->min_free;
ASSERT(disk->page_array[free_pos] == PAGE_UNSET_SENTINEL);
disk->page_array[free_pos] = page;
}
/**
* Mark \a page of \a disk as free.
- * \note max_free 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, pgcnt_t page)
+static bool battfs_markFree(struct BattFsSuper *disk, struct BattFsPageHeader *hdr, pgcnt_t page)
{
- pgaddr_t addr = disk->page_size - sizeof(BattFsPageHeader) + offsetof(BattFsPageHeader, mark);
- mark_t mark = cpu_to_mark_t(++disk->max_free);
- if (!disk->write(disk, page, addr, &mark, sizeof(mark)))
+ uint8_t buf[BATTFS_HEADER_LEN];
+
+ 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))
{
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 unsing
+ * at most half numbers of an mark_t type.
+ * The free blocks algorith 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;
- rotating_t cks;
- pgoff_t filelen_table[BATTFS_MAX_FILES];
+ /* 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 end in upper */
+ disk->free_start = minl;
+ disk->free_next = maxh;
+ }
+ else
+ {
+ /* Interval starts in upper half and end 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.
+ */
+ TRACEMSG("No valid marked free block found, new disk?\n");
+ disk->free_start = 0;
+ disk->free_next = -1; //to be incremented ahead
}
- memset(filelen_table, 0, BATTFS_MAX_FILES * sizeof(pgoff_t));
+ /* free_next should contain the first usable address */
+ disk->free_next++;
- /* Initialize min free sequence number to max value */
- disk->min_free = MARK_PAGE_VALID;
- /* Initialize max free sequence number to min value */
- disk->max_free = 0;
+ 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);
+}
- disk->free_bytes = 0;
- disk->disk_size = (disk_size_t)(disk->page_size - sizeof(BattFsPageHeader)) * disk->page_count;
+/**
+ * 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;
- /* Count the number of disk page per files */
+ /* 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;
+
+
+ /* Count the number of disk page per file */
for (pgcnt_t page = 0; page < disk->page_count; page++)
{
if (!battfs_readHeader(disk, page, &hdr))
return false;
/* Check header FCS */
- rotating_init(&cks);
- rotating_update(&hdr, sizeof(BattFsPageHeader) - sizeof(rotating_t), &cks);
- if (cks == hdr.fcs)
+ if (hdr.fcs == computeFcs(&hdr))
{
+ 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]++;
- ASSERT(hdr.mark == MARK_PAGE_VALID);
- ASSERT(hdr.fill <= disk->page_size - sizeof(BattFsPageHeader));
/* Keep trace of free space */
- disk->free_bytes += disk->page_size - sizeof(BattFsPageHeader) - hdr.fill;
+ disk->free_bytes += disk->page_size - BATTFS_HEADER_LEN - hdr.fill;
}
else
{
/* Increase free space */
- disk->free_bytes += disk->page_size - sizeof(BattFsPageHeader);
+ disk->free_bytes += disk->page_size - BATTFS_HEADER_LEN;
- /* Check if setting mark to MARK_PAGE_VALID makes fcs correct */
- mark_t old_mark = hdr.mark;
- hdr.mark = MARK_PAGE_VALID;
- rotating_init(&cks);
- rotating_update(&hdr, sizeof(BattFsPageHeader) - sizeof(rotating_t), &cks);
- if (cks == hdr.fcs)
+ /* Check if page is marked free */
+ if (hdr.fcs_free == computeFcsFree(&hdr))
{
/*
* This page is a valid and marked free page.
- * Update min and max free page sequence numbers.
+ * Update min and max free page markers.
*/
- disk->min_free = MIN(disk->min_free, old_mark);
- disk->max_free = MAX(disk->max_free, old_mark);
+ if (hdr.mark < MARK_HALF_SIZE)
+ {
+ minl = MIN(minl, hdr.mark);
+ maxl = MAX(maxl, hdr.mark);
+ }
+ else
+ {
+ minh = MIN(minh, 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;
-
+/**
+ * Fill page allocation array of \a disk
+ * using file lenghts in \a filelen_table.
+ *
+ * The page allocation array is an array containings all files info.
+ * 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++)
{
return false;
/* Check header FCS */
- rotating_init(&cks);
- rotating_update(&hdr, sizeof(BattFsPageHeader) - sizeof(rotating_t), &cks);
- if (cks == hdr.fcs)
+ if (hdr.fcs == computeFcs(&hdr))
{
/* Page is valid and is owned by a file */
ASSERT(hdr.mark == MARK_PAGE_VALID);
+ ASSERT(hdr.fcs_free == FCS_FREE_VALID);
/* Compute array position */
pgcnt_t array_pos = countPages(filelen_table, hdr.inode);
array_pos += hdr.pgoff;
/* Check if position is already used by another page of the same file */
- if (disk->page_array[array_pos] == PAGE_UNSET_SENTINEL)
+ if (LIKELY(disk->page_array[array_pos] == PAGE_UNSET_SENTINEL))
disk->page_array[array_pos] = page;
else
{
if (!battfs_readHeader(disk, disk->page_array[array_pos], &hdr_old))
return false;
- #ifdef _DEBUG
/* Check header FCS */
- rotating_t cks_old;
- rotating_init(&cks_old);
- rotating_update(&hdr_old, sizeof(BattFsPageHeader) - sizeof(rotating_t), &cks_old);
- ASSERT(cks_old == hdr_old.fcs);
- #endif
+ ASSERT(hdr_old.fcs == computeFcs(&hdr_old));
/* Only the very same page with a different seq number can be here */
ASSERT(hdr.inode == hdr_old.inode);
ASSERT(hdr.pgoff == hdr_old.pgoff);
ASSERT(hdr.mark == hdr_old.mark);
+ ASSERT(hdr.fcs_free == hdr_old.fcs_free);
ASSERT(hdr.seq != hdr_old.seq);
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)
{
- /* Actual header is newer than the previuos one */
+ /* Current header is newer than the previuos one */
old_page = disk->page_array[array_pos];
new_page = page;
old_fill = hdr_old.fill;
filelen_table[hdr.inode]--;
/* Add old page to free pages pool */
- if (!battfs_markFree(disk, old_page))
+ if (!battfs_markFree(disk, &hdr, old_page))
return false;
- insertFreePage(disk, filelen_table, disk->max_free, old_page);
+ insertFreePage(disk, hdr.mark, old_page);
}
}
else
{
- /* Check if setting mark to MARK_PAGE_VALID makes fcs correct */
- mark_t mark = hdr.mark;
- hdr.mark = MARK_PAGE_VALID;
- rotating_init(&cks);
- rotating_update(&hdr, sizeof(BattFsPageHeader) - sizeof(rotating_t), &cks);
- if (cks != hdr.fcs)
- /* Page is not a valid marked page, insert at the end of list */
- mark = ++disk->max_free;
-
- insertFreePage(disk, filelen_table, mark, page);
+ /* Check if page is free */
+ if (hdr.fcs_free != computeFcsFree(&hdr))
+ /* Page is not a valid marked page, insert at list beginning */
+ hdr.mark = --disk->free_start;
+
+ 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 */
+
+ /* 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;
+ }
- #warning Test me!
return true;
}
projects / bertos.git / blobdiff