* avoided. In my test with the hint to prev_badblocks(), except for the first
* loop, all rested calls to prev_badblocks() can go into the fast path and
* return correct bad blocks table index immediately.
+ *
+ *
+ * Clearing a bad blocks range from the bad block table has similar idea as
+ * setting does, but much more simpler. The only thing needs to be noticed is
+ * when the clearing range hits middle of a bad block range, the existing bad
+ * block range will split into two, and one more item should be added into the
+ * bad block table. The simplified situations to be considered are, (The already
+ * set bad blocks ranges in bad block table are naming with prefix E, and the
+ * clearing bad blocks range is naming with prefix C)
+ *
+ * 1) A clearing range is not overlapped to any already set ranges in bad block
+ * table.
+ * +-----+ | +-----+ | +-----+
+ * | C | | | C | | | C |
+ * +-----+ or +-----+ or +-----+
+ * +---+ | +----+ +----+ | +---+
+ * | E | | | E1 | | E2 | | | E |
+ * +---+ | +----+ +----+ | +---+
+ * For the above situations, no bad block to be cleared and no failure
+ * happens, simply returns 0.
+ * 2) The clearing range hits middle of an already setting bad blocks range in
+ * the bad block table.
+ * +---+
+ * | C |
+ * +---+
+ * +-----------------+
+ * | E |
+ * +-----------------+
+ * In this situation if the bad block table is not full, the range E will be
+ * split into two ranges E1 and E2. The result is,
+ * +------+ +------+
+ * | E1 | | E2 |
+ * +------+ +------+
+ * 3) The clearing range starts exactly at same LBA as an already set bad block range
+ * from the bad block table.
+ * 3.1) Partially covered at head part
+ * +------------+
+ * | C |
+ * +------------+
+ * +-----------------+
+ * | E |
+ * +-----------------+
+ * For this situation, the overlapped already set range will update the
+ * start LBA to end of C and shrink the range to BB_LEN(E) - BB_LEN(C). No
+ * item deleted from bad block table. The result is,
+ * +----+
+ * | E1 |
+ * +----+
+ * 3.2) Exact fully covered
+ * +-----------------+
+ * | C |
+ * +-----------------+
+ * +-----------------+
+ * | E |
+ * +-----------------+
+ * For this situation the whole bad blocks range E will be cleared and its
+ * corresponded item is deleted from the bad block table.
+ * 4) The clearing range exactly ends at same LBA as an already set bad block
+ * range.
+ * +-------+
+ * | C |
+ * +-------+
+ * +-----------------+
+ * | E |
+ * +-----------------+
+ * For the above situation, the already set range E is updated to shrink its
+ * end to the start of C, and reduce its length to BB_LEN(E) - BB_LEN(C).
+ * The result is,
+ * +---------+
+ * | E |
+ * +---------+
+ * 5) The clearing range is partially overlapped with an already set bad block
+ * range from the bad block table.
+ * 5.1) The already set bad block range is front overlapped with the clearing
+ * range.
+ * +----------+
+ * | C |
+ * +----------+
+ * +------------+
+ * | E |
+ * +------------+
+ * For such situation, the clearing range C can be treated as two parts. The
+ * first part ends at the start LBA of range E, and the second part starts at
+ * same LBA of range E.
+ * +----+-----+ +----+ +-----+
+ * | C1 | C2 | | C1 | | C2 |
+ * +----+-----+ ===> +----+ +-----+
+ * +------------+ +------------+
+ * | E | | E |
+ * +------------+ +------------+
+ * Now the first part C1 can be handled as condition 1), and the second part C2 can be
+ * handled as condition 3.1) in next loop.
+ * 5.2) The already set bad block range is behind overlaopped with the clearing
+ * range.
+ * +----------+
+ * | C |
+ * +----------+
+ * +------------+
+ * | E |
+ * +------------+
+ * For such situation, the clearing range C can be treated as two parts. The
+ * first part C1 ends at same end LBA of range E, and the second part starts
+ * at end LBA of range E.
+ * +----+-----+ +----+ +-----+
+ * | C1 | C2 | | C1 | | C2 |
+ * +----+-----+ ===> +----+ +-----+
+ * +------------+ +------------+
+ * | E | | E |
+ * +------------+ +------------+
+ * Now the first part clearing range C1 can be handled as condition 4), and
+ * the second part clearing range C2 can be handled as condition 1) in next
+ * loop.
+ *
+ * All bad blocks range clearing can be simplified into the above 5 situations
+ * by only handling the head part of the clearing range in each run of the
+ * while-loop. The idea is similar to bad blocks range setting but much
+ * simpler.
*/
/*
return rv;
}
+/*
+ * Clear the bad block range from bad block table which is front overlapped
+ * with the clearing range. The return value is how many sectors from an
+ * already set bad block range are cleared. If the whole bad block range is
+ * covered by the clearing range and fully cleared, 'delete' is set as 1 for
+ * the caller to reduce bb->count.
+ */
+static int front_clear(struct badblocks *bb, int prev,
+ struct badblocks_context *bad, int *deleted)
+{
+ sector_t sectors = bad->len;
+ sector_t s = bad->start;
+ u64 *p = bb->page;
+ int cleared = 0;
+
+ *deleted = 0;
+ if (s == BB_OFFSET(p[prev])) {
+ if (BB_LEN(p[prev]) > sectors) {
+ p[prev] = BB_MAKE(BB_OFFSET(p[prev]) + sectors,
+ BB_LEN(p[prev]) - sectors,
+ BB_ACK(p[prev]));
+ cleared = sectors;
+ } else {
+ /* BB_LEN(p[prev]) <= sectors */
+ cleared = BB_LEN(p[prev]);
+ if ((prev + 1) < bb->count)
+ memmove(p + prev, p + prev + 1,
+ (bb->count - prev - 1) * 8);
+ *deleted = 1;
+ }
+ } else if (s > BB_OFFSET(p[prev])) {
+ if (BB_END(p[prev]) <= (s + sectors)) {
+ cleared = BB_END(p[prev]) - s;
+ p[prev] = BB_MAKE(BB_OFFSET(p[prev]),
+ s - BB_OFFSET(p[prev]),
+ BB_ACK(p[prev]));
+ } else {
+ /* Splitting is handled in front_splitting_clear() */
+ BUG();
+ }
+ }
+
+ return cleared;
+}
+
+/*
+ * Handle the condition that the clearing range hits middle of an already set
+ * bad block range from bad block table. In this condition the existing bad
+ * block range is split into two after the middle part is cleared.
+ */
+static int front_splitting_clear(struct badblocks *bb, int prev,
+ struct badblocks_context *bad)
+{
+ u64 *p = bb->page;
+ u64 end = BB_END(p[prev]);
+ int ack = BB_ACK(p[prev]);
+ sector_t sectors = bad->len;
+ sector_t s = bad->start;
+
+ p[prev] = BB_MAKE(BB_OFFSET(p[prev]),
+ s - BB_OFFSET(p[prev]),
+ ack);
+ memmove(p + prev + 2, p + prev + 1, (bb->count - prev - 1) * 8);
+ p[prev + 1] = BB_MAKE(s + sectors, end - s - sectors, ack);
+ return sectors;
+}
+
+/* Do the exact work to clear bad block range from the bad block table */
+static int _badblocks_clear(struct badblocks *bb, sector_t s, int sectors)
+{
+ struct badblocks_context bad;
+ int prev = -1, hint = -1;
+ int len = 0, cleared = 0;
+ int rv = 0;
+ u64 *p;
+
+ if (bb->shift < 0)
+ /* badblocks are disabled */
+ return 1;
+
+ if (sectors == 0)
+ /* Invalid sectors number */
+ return 1;
+
+ if (bb->shift) {
+ sector_t target;
+
+ /* When clearing we round the start up and the end down.
+ * This should not matter as the shift should align with
+ * the block size and no rounding should ever be needed.
+ * However it is better the think a block is bad when it
+ * isn't than to think a block is not bad when it is.
+ */
+ target = s + sectors;
+ roundup(s, bb->shift);
+ rounddown(target, bb->shift);
+ sectors = target - s;
+ }
+
+ write_seqlock_irq(&bb->lock);
+
+ bad.ack = true;
+ p = bb->page;
+
+re_clear:
+ bad.start = s;
+ bad.len = sectors;
+
+ if (badblocks_empty(bb)) {
+ len = sectors;
+ cleared++;
+ goto update_sectors;
+ }
+
+
+ prev = prev_badblocks(bb, &bad, hint);
+
+ /* Start before all badblocks */
+ if (prev < 0) {
+ if (overlap_behind(bb, &bad, 0)) {
+ len = BB_OFFSET(p[0]) - s;
+ hint = 0;
+ } else {
+ len = sectors;
+ }
+ /*
+ * Both situations are to clear non-bad range,
+ * should be treated as successful
+ */
+ cleared++;
+ goto update_sectors;
+ }
+
+ /* Start after all badblocks */
+ if ((prev + 1) >= bb->count && !overlap_front(bb, prev, &bad)) {
+ len = sectors;
+ cleared++;
+ goto update_sectors;
+ }
+
+ /* Clear will split a bad record but the table is full */
+ if (badblocks_full(bb) && (BB_OFFSET(p[prev]) < bad.start) &&
+ (BB_END(p[prev]) > (bad.start + sectors))) {
+ len = sectors;
+ goto update_sectors;
+ }
+
+ if (overlap_front(bb, prev, &bad)) {
+ if ((BB_OFFSET(p[prev]) < bad.start) &&
+ (BB_END(p[prev]) > (bad.start + bad.len))) {
+ /* Splitting */
+ if ((bb->count + 1) < MAX_BADBLOCKS) {
+ len = front_splitting_clear(bb, prev, &bad);
+ bb->count += 1;
+ cleared++;
+ } else {
+ /* No space to split, give up */
+ len = sectors;
+ }
+ } else {
+ int deleted = 0;
+
+ len = front_clear(bb, prev, &bad, &deleted);
+ bb->count -= deleted;
+ cleared++;
+ hint = prev;
+ }
+
+ goto update_sectors;
+ }
+
+ /* Not front overlap, but behind overlap */
+ if ((prev + 1) < bb->count && overlap_behind(bb, &bad, prev + 1)) {
+ len = BB_OFFSET(p[prev + 1]) - bad.start;
+ hint = prev + 1;
+ /* Clear non-bad range should be treated as successful */
+ cleared++;
+ goto update_sectors;
+ }
+
+ /* Not cover any badblocks range in the table */
+ len = sectors;
+ /* Clear non-bad range should be treated as successful */
+ cleared++;
+
+update_sectors:
+ s += len;
+ sectors -= len;
+
+ if (sectors > 0)
+ goto re_clear;
+
+ WARN_ON(sectors < 0);
+
+ if (cleared) {
+ badblocks_update_acked(bb);
+ set_changed(bb);
+ }
+
+ write_sequnlock_irq(&bb->lock);
+
+ if (!cleared)
+ rv = 1;
+
+ return rv;
+}
+
+
/**
* badblocks_check() - check a given range for bad sectors
* @bb: the badblocks structure that holds all badblock information
projects / linux-block.git / blobdiff