diff --git a/block/badblocks.c b/block/badblocks.c
index e216c6791b4b..13eaad18be15 100644
--- a/block/badblocks.c
+++ b/block/badblocks.c
@@ -16,6 +16,322 @@
 #include <linux/types.h>
 #include <linux/slab.h>
 
+/*
+ * The purpose of badblocks set/clear is to manage bad blocks ranges which are
+ * identified by LBA addresses.
+ *
+ * When the caller of badblocks_set() wants to set a range of bad blocks, the
+ * setting range can be acked or unacked. And the setting range may merge,
+ * overwrite, skip the overlaypped already set range, depends on who they are
+ * overlapped or adjacent, and the acknowledgment type of the ranges. It can be
+ * more complicated when the setting range covers multiple already set bad block
+ * ranges, with restritctions of maximum length of each bad range and the bad
+ * table space limitation.
+ *
+ * It is difficut and unnecessary to take care of all the possible situations,
+ * for setting a large range of bad blocks, we can handle it by dividing the
+ * large range into smaller ones when encounter overlap, max range length or
+ * bad table full conditions. Every time only a smaller piece of the bad range
+ * is handled with a limited number of conditions how it is interacted with
+ * possible overlapped or adjacent already set bad block ranges. Then the hard
+ * complicated problem can be much simpler to habndle in proper way.
+ *
+ * When setting a range of bad blocks to the bad table, the simplified situations
+ * to be considered are, (The already set bad blocks ranges are naming with
+ *  prefix E, and the setting bad blocks range is naming with prefix S)
+ *
+ * 1) A setting range is not overlapped or adjacent to any other already set bad
+ *    block range.
+ *                         +--------+
+ *                         |    S   |
+ *                         +--------+
+ *        +-------------+               +-------------+
+ *        |      E1     |               |      E2     |
+ *        +-------------+               +-------------+
+ *    For this situation if the bad blocks table is not full, just allocate a
+ *    free slot from the bad blocks table to mark the setting range S. The
+ *    result is,
+ *        +-------------+  +--------+   +-------------+
+ *        |      E1     |  |    S   |   |      E2     |
+ *        +-------------+  +--------+   +-------------+
+ * 2) A setting range starts exactly at a start LBA of an already set bad blocks
+ *    range.
+ * 2.1) The setting range size < already set range size
+ *        +--------+
+ *        |    S   |
+ *        +--------+
+ *        +-------------+
+ *        |      E      |
+ *        +-------------+
+ * 2.1.1) If S and E are both acked or unacked range, the setting range S can
+ *    be merged into existing bad range E. The result is,
+ *        +-------------+
+ *        |      S      |
+ *        +-------------+
+ * 2.1.2) If S is uncked setting and E is acked, the setting will be denied, and
+ *    the result is,
+ *        +-------------+
+ *        |      E      |
+ *        +-------------+
+ * 2.1.3) If S is acked setting and E is unacked, range S can overwirte on E.
+ *    An extra slot from the bad blocks table will be allocated for S, and head
+ *    of E will move to end of the inserted range E. The result is,
+ *        +--------+----+
+ *        |    S   | E  |
+ *        +--------+----+
+ * 2.2) The setting range size == already set range size
+ * 2.2.1) If S and E are both acked or unacked range, the setting range S can
+ *    be merged into existing bad range E. The result is,
+ *        +-------------+
+ *        |      S      |
+ *        +-------------+
+ * 2.2.2) If S is uncked setting and E is acked, the setting will be denied, and
+ *    the result is,
+ *        +-------------+
+ *        |      E      |
+ *        +-------------+
+ * 2.2.3) If S is acked setting and E is unacked, range S can overwirte all of
+      bad blocks range E. The result is,
+ *        +-------------+
+ *        |      S      |
+ *        +-------------+
+ * 2.3) The setting range size > already set range size
+ *        +-------------------+
+ *        |          S        |
+ *        +-------------------+
+ *        +-------------+
+ *        |      E      |
+ *        +-------------+
+ *    For such situation, the setting range S can be treated as two parts, the
+ *    first part (S1) is as same size as the already set range E, the second
+ *    part (S2) is the rest of setting range.
+ *        +-------------+-----+        +-------------+       +-----+
+ *        |    S1       | S2  |        |     S1      |       | S2  |
+ *        +-------------+-----+  ===>  +-------------+       +-----+
+ *        +-------------+              +-------------+
+ *        |      E      |              |      E      |
+ *        +-------------+              +-------------+
+ *    Now we only focus on how to handle the setting range S1 and already set
+ *    range E, which are already explained in 1.2), for the rest S2 it will be
+ *    handled later in next loop.
+ * 3) A setting range starts before the start LBA of an already set bad blocks
+ *    range.
+ *        +-------------+
+ *        |      S      |
+ *        +-------------+
+ *             +-------------+
+ *             |      E      |
+ *             +-------------+
+ *    For this situation, the setting range S can be divided into two parts, the
+ *    first (S1) ends at the start LBA of already set range E, the second part
+ *    (S2) starts exactly at a start LBA of the already set range E.
+ *        +----+---------+             +----+      +---------+
+ *        | S1 |    S2   |             | S1 |      |    S2   |
+ *        +----+---------+      ===>   +----+      +---------+
+ *             +-------------+                     +-------------+
+ *             |      E      |                     |      E      |
+ *             +-------------+                     +-------------+
+ *    Now only the first part S1 should be handled in this loop, which is in
+ *    similar condition as 1). The rest part S2 has exact same start LBA address
+ *    of the already set range E, they will be handled in next loop in one of
+ *    situations in 2).
+ * 4) A setting range starts after the start LBA of an already set bad blocks
+ *    range.
+ * 4.1) If the setting range S exactly matches the tail part of already set bad
+ *    blocks range E, like the following chart shows,
+ *            +---------+
+ *            |   S     |
+ *            +---------+
+ *        +-------------+
+ *        |      E      |
+ *        +-------------+
+ * 4.1.1) If range S and E have same ackknowledg value (both acked or unacked),
+ *    they will be merged into one, the result is,
+ *        +-------------+
+ *        |      S      |
+ *        +-------------+
+ * 4.1.2) If range E is acked and the setting range S is unacked, the setting
+ *    request of S will be rejected, the result is,
+ *        +-------------+
+ *        |      E      |
+ *        +-------------+
+ * 4.1.3) If range E is unacked, and the setting range S is acked, then S may
+ *    overwrite the overlapped range of E, the result is,
+ *        +---+---------+
+ *        | E |    S    |
+ *        +---+---------+
+ * 4.2) If the setting range S stays in middle of an already set range E, like
+ *    the following chart shows,
+ *             +----+
+ *             | S  |
+ *             +----+
+ *        +--------------+
+ *        |       E      |
+ *        +--------------+
+ * 4.2.1) If range S and E have same ackknowledg value (both acked or unacked),
+ *    they will be merged into one, the result is,
+ *        +--------------+
+ *        |       S      |
+ *        +--------------+
+ * 4.2.2) If range E is acked and the setting range S is unacked, the setting
+ *    request of S will be rejected, the result is also,
+ *        +--------------+
+ *        |       E      |
+ *        +--------------+
+ * 4.2.3) If range E is unacked, and the setting range S is acked, then S will
+ *    inserted into middle of E and split previous range E into twp parts (E1
+ *    and E2), the result is,
+ *        +----+----+----+
+ *        | E1 |  S | E2 |
+ *        +----+----+----+
+ * 4.3) If the setting bad blocks range S is overlapped with an already set bad
+ *    blocks range E. The range S starts after the start LBA of range E, and
+ *    ends after the end LBA of range E, as the following chart shows,
+ *            +-------------------+
+ *            |          S        |
+ *            +-------------------+
+ *        +-------------+
+ *        |      E      |
+ *        +-------------+
+ *    For this situation the range S can be divided into two parts, the first
+ *    part (S1) ends at end range E, and the second part (S2) has rest range of
+ *    origin S.
+ *            +---------+---------+            +---------+      +---------+
+ *            |    S1   |    S2   |            |    S1   |      |    S2   |
+ *            +---------+---------+  ===>      +---------+      +---------+
+ *        +-------------+                  +-------------+
+ *        |      E      |                  |      E      |
+ *        +-------------+                  +-------------+
+ *     Now in this loop the setting range S1 and already set range E can be
+ *     handled as the situations 4), the rest range S2 will be handled in next
+ *     loop and ignored in this loop.
+ * 5) A setting bad blocks range S is adjacent to one or more already set bad
+ *    blocks range(s), and they are all acked or unacked range.
+ * 5.1) Front merge: If the already set bad blocks range E is before setting
+ *    range S and they are adjacent,
+ *                +------+
+ *                |  S   |
+ *                +------+
+ *        +-------+
+ *        |   E   |
+ *        +-------+
+ * 5.1.1) When total size of range S and E <= BB_MAX_LEN, and their acknowledge
+ *    values are same, the setting range S can front merges into range E. The
+ *    result is,
+ *        +--------------+
+ *        |       S      |
+ *        +--------------+
+ * 5.1.2) Otherwise these two ranges cannot merge, just insert the setting
+ *    range S right after already set range E into the bad blocks table. The
+ *    result is,
+ *        +--------+------+
+ *        |   E    |   S  |
+ *        +--------+------+
+ * 6) Special cases which above conditions cannot handle
+ * 6.1) Multiple already set ranges may merge into less ones in a full bad table
+ *        +-------------------------------------------------------+
+ *        |                           S                           |
+ *        +-------------------------------------------------------+
+ *        |<----- BB_MAX_LEN ----->|
+ *                                 +-----+     +-----+   +-----+
+ *                                 | E1  |     | E2  |   | E3  |
+ *                                 +-----+     +-----+   +-----+
+ *     In the above example, when the bad blocks table is full, inserting the
+ *     first part of setting range S will fail because no more available slot
+ *     can be allocated from bad blocks table. In this situation a proper
+ *     setting method should be go though all the setting bad blocks range and
+ *     look for chance to merge already set ranges into less ones. When there
+ *     is available slot from bad blocks table, re-try again to handle more
+ *     setting bad blocks ranges as many as possible.
+ *        +------------------------+
+ *        |          S3            |
+ *        +------------------------+
+ *        |<----- BB_MAX_LEN ----->|
+ *                                 +-----+-----+-----+---+-----+--+
+ *                                 |       S1        |     S2     |
+ *                                 +-----+-----+-----+---+-----+--+
+ *     The above chart shows although the first part (S3) cannot be inserted due
+ *     to no-space in bad blocks table, but the following E1, E2 and E3 ranges
+ *     can be merged with rest part of S into less range S1 and S2. Now there is
+ *     1 free slot in bad blocks table.
+ *        +------------------------+-----+-----+-----+---+-----+--+
+ *        |           S3           |       S1        |     S2     |
+ *        +------------------------+-----+-----+-----+---+-----+--+
+ *     Since the bad blocks table is not full anymore, re-try again for the
+ *     origin setting range S. Now the setting range S3 can be inserted into the
+ *     bad blocks table with previous freed slot from multiple ranges merge.
+ * 6.2) Front merge after overwrite
+ *    In the following example, in bad blocks table, E1 is an acked bad blocks
+ *    range and E2 is an unacked bad blocks range, therefore they are not able
+ *    to merge into a larger range. The setting bad blocks range S is acked,
+ *    therefore part of E2 can be overwritten by S.
+ *                      +--------+
+ *                      |    S   |                             acknowledged
+ *                      +--------+                         S:       1
+ *              +-------+-------------+                   E1:       1
+ *              |   E1  |    E2       |                   E2:       0
+ *              +-------+-------------+
+ *     With previosu simplified routines, after overwiting part of E2 with S,
+ *     the bad blocks table should be (E3 is remaining part of E2 which is not
+ *     overwritten by S),
+ *                                                             acknowledged
+ *              +-------+--------+----+                    S:       1
+ *              |   E1  |    S   | E3 |                   E1:       1
+ *              +-------+--------+----+                   E3:       0
+ *     The above result is correct but not perfect. Range E1 and S in the bad
+ *     blocks table are all acked, merging them into a larger one range may
+ *     occupy less bad blocks table space and make badblocks_check() faster.
+ *     Therefore in such situation, after overwiting range S, the previous range
+ *     E1 should be checked for possible front combination. Then the ideal
+ *     result can be,
+ *              +----------------+----+                        acknowledged
+ *              |       E1       | E3 |                   E1:       1
+ *              +----------------+----+                   E3:       0
+ * 6.3) Behind merge: If the already set bad blocks range E is behind the setting
+ *    range S and they are adjacent. Normally we don't need to care about this
+ *    because front merge handles this while going though range S from head to
+ *    tail, except for the tail part of range S. When the setting range S are
+ *    fully handled, all the above simplified routine doesn't check whether the
+ *    tail LBA of range S is adjacent to the next already set range and not able
+ *    to them if they are mergeable.
+ *        +------+
+ *        |  S   |
+ *        +------+
+ *               +-------+
+ *               |   E   |
+ *               +-------+
+ *    For the above special stiuation, when the setting range S are all handled
+ *    and the loop ends, an extra check is necessary for whether next already
+ *    set range E is right after S and mergeable.
+ * 6.2.1) When total size of range E and S <= BB_MAX_LEN, and their acknowledge
+ *    values are same, the setting range S can behind merges into range E. The
+ *    result is,
+ *        +--------------+
+ *        |       S      |
+ *        +--------------+
+ * 6.2.2) Otherwise these two ranges cannot merge, just insert the setting range
+ *     S infront of the already set range E in the bad blocks table. The result
+ *     is,
+ *        +------+-------+
+ *        |  S   |   E   |
+ *        +------+-------+
+ *
+ * All the above 5 simplified situations and 3 special cases may cover 99%+ of
+ * the bad block range setting conditions. Maybe there is some rare corner case
+ * is not considered and optimized, it won't hurt if badblocks_set() fails due
+ * to no space, or some ranges are not merged to save bad blocks table space.
+ *
+ * Inside badblocks_set() each loop starts by jumping to re_insert label, every
+ * time for the new loop prev_badblocks() is called to find an already set range
+ * which starts before or at current setting range. Since the setting bad blocks
+ * range is handled from head to tail, most of the cases it is unnecessary to do
+ * the binary search inside prev_badblocks(), it is possible to provide a hint
+ * to prev_badblocks() for a fast path, then the expensive binary search can be
+ * 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.
+ */
+
 /*
  * Find the range starts at-or-before 's' from bad table. The search
  * starts from index 'hint' and stops at index 'hint_end' from the bad
@@ -390,6 +706,230 @@ static int insert_at(struct badblocks *bb, int at, struct badblocks_context *bad
 	return len;
 }
 
+static void badblocks_update_acked(struct badblocks *bb)
+{
+	bool unacked = false;
+	u64 *p = bb->page;
+	int i;
+
+	if (!bb->unacked_exist)
+		return;
+
+	for (i = 0; i < bb->count ; i++) {
+		if (!BB_ACK(p[i])) {
+			unacked = true;
+			break;
+		}
+	}
+
+	if (!unacked)
+		bb->unacked_exist = 0;
+}
+
+/* Do exact work to set bad block range into the bad block table */
+static int _badblocks_set(struct badblocks *bb, sector_t s, int sectors,
+			  int acknowledged)
+{
+	int retried = 0, space_desired = 0;
+	int orig_len, len = 0, added = 0;
+	struct badblocks_context bad;
+	int prev = -1, hint = -1;
+	sector_t orig_start;
+	unsigned long flags;
+	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) {
+		/* round the start down, and the end up */
+		sector_t next = s + sectors;
+
+		rounddown(s, bb->shift);
+		roundup(next, bb->shift);
+		sectors = next - s;
+	}
+
+	write_seqlock_irqsave(&bb->lock, flags);
+
+	orig_start = s;
+	orig_len = sectors;
+	bad.ack = acknowledged;
+	p = bb->page;
+
+re_insert:
+	bad.start = s;
+	bad.len = sectors;
+	len = 0;
+
+	if (badblocks_empty(bb)) {
+		len = insert_at(bb, 0, &bad);
+		bb->count++;
+		added++;
+		goto update_sectors;
+	}
+
+	prev = prev_badblocks(bb, &bad, hint);
+
+	/* start before all badblocks */
+	if (prev < 0) {
+		if (!badblocks_full(bb)) {
+			/* insert on the first */
+			if (bad.len > (BB_OFFSET(p[0]) - bad.start))
+				bad.len = BB_OFFSET(p[0]) - bad.start;
+			len = insert_at(bb, 0, &bad);
+			bb->count++;
+			added++;
+			hint = 0;
+			goto update_sectors;
+		}
+
+		/* No sapce, try to merge */
+		if (overlap_behind(bb, &bad, 0)) {
+			if (can_merge_behind(bb, &bad, 0)) {
+				len = behind_merge(bb, &bad, 0);
+				added++;
+			} else {
+				len = min_t(sector_t,
+					    BB_OFFSET(p[0]) - s, sectors);
+				space_desired = 1;
+			}
+			hint = 0;
+			goto update_sectors;
+		}
+
+		/* no table space and give up */
+		goto out;
+	}
+
+	/* in case p[prev-1] can be merged with p[prev] */
+	if (can_combine_front(bb, prev, &bad)) {
+		front_combine(bb, prev);
+		bb->count--;
+		added++;
+		hint = prev;
+		goto update_sectors;
+	}
+
+	if (overlap_front(bb, prev, &bad)) {
+		if (can_merge_front(bb, prev, &bad)) {
+			len = front_merge(bb, prev, &bad);
+			added++;
+		} else {
+			int extra = 0;
+
+			if (!can_front_overwrite(bb, prev, &bad, &extra)) {
+				len = min_t(sector_t,
+					    BB_END(p[prev]) - s, sectors);
+				hint = prev;
+				goto update_sectors;
+			}
+
+			len = front_overwrite(bb, prev, &bad, extra);
+			added++;
+			bb->count += extra;
+
+			if (can_combine_front(bb, prev, &bad)) {
+				front_combine(bb, prev);
+				bb->count--;
+			}
+		}
+		hint = prev;
+		goto update_sectors;
+	}
+
+	if (can_merge_front(bb, prev, &bad)) {
+		len = front_merge(bb, prev, &bad);
+		added++;
+		hint = prev;
+		goto update_sectors;
+	}
+
+	/* if no space in table, still try to merge in the covered range */
+	if (badblocks_full(bb)) {
+		/* skip the cannot-merge range */
+		if (((prev + 1) < bb->count) &&
+		    overlap_behind(bb, &bad, prev + 1) &&
+		    ((s + sectors) >= BB_END(p[prev + 1]))) {
+			len = BB_END(p[prev + 1]) - s;
+			hint = prev + 1;
+			goto update_sectors;
+		}
+
+		/* no retry any more */
+		len = sectors;
+		space_desired = 1;
+		hint = -1;
+		goto update_sectors;
+	}
+
+	/* cannot merge and there is space in bad table */
+	if ((prev + 1) < bb->count &&
+	    overlap_behind(bb, &bad, prev + 1))
+		bad.len = min_t(sector_t,
+				bad.len, BB_OFFSET(p[prev + 1]) - bad.start);
+
+	len = insert_at(bb, prev + 1, &bad);
+	bb->count++;
+	added++;
+	hint = prev + 1;
+
+update_sectors:
+	s += len;
+	sectors -= len;
+
+	if (sectors > 0)
+		goto re_insert;
+
+	WARN_ON(sectors < 0);
+
+	/* Check whether the following already set range can be merged */
+	if ((prev + 1) < bb->count &&
+	    BB_END(p[prev]) == BB_OFFSET(p[prev + 1]) &&
+	    (BB_LEN(p[prev]) + BB_LEN(p[prev + 1])) <= BB_MAX_LEN &&
+	    BB_ACK(p[prev]) == BB_ACK(p[prev + 1])) {
+		p[prev] = BB_MAKE(BB_OFFSET(p[prev]),
+				  BB_LEN(p[prev]) + BB_LEN(p[prev + 1]),
+				  BB_ACK(p[prev]));
+
+		if ((prev + 2) < bb->count)
+			memmove(p + prev + 1, p + prev + 2,
+				(bb->count -  (prev + 2)) * 8);
+		bb->count--;
+	}
+
+	if (space_desired && !badblocks_full(bb)) {
+		s = orig_start;
+		sectors = orig_len;
+		space_desired = 0;
+		if (retried++ < 3)
+			goto re_insert;
+	}
+
+out:
+	if (added) {
+		set_changed(bb);
+
+		if (!acknowledged)
+			bb->unacked_exist = 1;
+		else
+			badblocks_update_acked(bb);
+	}
+
+	write_sequnlock_irqrestore(&bb->lock, flags);
+
+	if (!added)
+		rv = 1;
+
+	return rv;
+}
+
 /**
  * badblocks_check() - check a given range for bad sectors
  * @bb:		the badblocks structure that holds all badblock information
@@ -499,26 +1039,6 @@ int badblocks_check(struct badblocks *bb, sector_t s, int sectors,
 }
 EXPORT_SYMBOL_GPL(badblocks_check);
 
-static void badblocks_update_acked(struct badblocks *bb)
-{
-	u64 *p = bb->page;
-	int i;
-	bool unacked = false;
-
-	if (!bb->unacked_exist)
-		return;
-
-	for (i = 0; i < bb->count ; i++) {
-		if (!BB_ACK(p[i])) {
-			unacked = true;
-			break;
-		}
-	}
-
-	if (!unacked)
-		bb->unacked_exist = 0;
-}
-
 /**
  * badblocks_set() - Add a range of bad blocks to the table.
  * @bb:		the badblocks structure that holds all badblock information
