diff --git a/block/badblocks.c b/block/badblocks.c
index 7e7f9f14bb1d35069fe7006897bf9e0fb7620c24..010c8132f94a48c1999a26e1f8c1a36cc18ab472 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 overlapped 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 restrictions of maximum length of each bad range and the bad
+ * table space limitation.
+ *
+ * It is difficult 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 handle 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 unacked 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 overwrite 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 S. 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 unacked 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 overwrite 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 2.2), 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 acknowledge 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 acknowledge 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 two 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 4.1), 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 previous simplified routines, after overwriting 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 overwriting 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
+ * merge them even it is possible.
+ * +------+
+ * | S |
+ * +------+
+ * +-------+
+ * | E |
+ * +-------+
+ * For the above special situation, 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.
+ * 6.3.1) 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 |
+ * +--------------+
+ * 6.3.2) Otherwise these two ranges cannot merge, just insert the setting range
+ * S in front 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
@@ -402,6 +718,234 @@ 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 = BB_OFFSET(p[0]) - s;
+ 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. (prev < 0) condition is not handled here,
+ * because it's already complicated enough.
+ */
+ if (prev >= 0 &&
+ (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
@@ -510,26 +1054,6 @@ 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