// SPDX-License-Identifier: GPL-2.0
/*
* Bad block management
*
* - Heavily based on MD badblocks code from Neil Brown
*
* Copyright (c) 2015, Intel Corporation.
*/
#include <linux/badblocks.h>
#include <linux/seqlock.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/stddef.h>
#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.
*
*
* 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.
*/
/*
* 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
* table.
*/
static int prev_by_hint(struct badblocks *bb, sector_t s, int hint)
{
int hint_end = hint + 2;
u64 *p = bb->page;
int ret = -1;
while ((hint < hint_end) && ((hint + 1) <= bb->count) &&
(BB_OFFSET(p[hint]) <= s)) {
if ((hint + 1) == bb->count || BB_OFFSET(p[hint + 1]) > s) {
ret = hint;
break;
}
hint++;
}
return ret;
}
/*
* Find the range starts at-or-before bad->start. If 'hint' is provided
* (hint >= 0) then search in the bad table from hint firstly. It is
* very probably the wanted bad range can be found from the hint index,
* then the unnecessary while-loop iteration can be avoided.
*/
static int prev_badblocks(struct badblocks *bb, struct badblocks_context *bad,
int hint)
{
sector_t s = bad->start;
int ret = -1;
int lo, hi;
u64 *p;
if (!bb->count)
goto out;
if (hint >= 0) {
ret = prev_by_hint(bb, s, hint);
if (ret >= 0)
goto out;
}
lo = 0;
hi = bb->count;
p = bb->page;
/* The following bisect search might be unnecessary */
if (BB_OFFSET(p[lo]) > s)
return -1;
if (BB_OFFSET(p[hi - 1]) <= s)
return hi - 1;
/* Do bisect search in bad table */
while (hi - lo > 1) {
int mid = (lo + hi)/2;
sector_t a = BB_OFFSET(p[mid]);
if (a == s) {
ret = mid;
goto out;
}
if (a < s)
lo = mid;
else
hi = mid;
}
if (BB_OFFSET(p[lo]) <= s)
ret = lo;
out:
return ret;
}
/*
* Return 'true' if the range indicated by 'bad' can be backward merged
* with the bad range (from the bad table) index by 'behind'.
*/
static bool can_merge_behind(struct badblocks *bb,
struct badblocks_context *bad, int behind)
{
sector_t sectors = bad->len;
sector_t s = bad->start;
u64 *p = bb->page;
if ((s < BB_OFFSET(p[behind])) &&
((s + sectors) >= BB_OFFSET(p[behind])) &&
((BB_END(p[behind]) - s) <= BB_MAX_LEN) &&
BB_ACK(p[behind]) == bad->ack)
return true;
return false;
}
/*
* Do backward merge for range indicated by 'bad' and the bad range
* (from the bad table) indexed by 'behind'. The return value is merged
* sectors from bad->len.
*/
static int behind_merge(struct badblocks *bb, struct badblocks_context *bad,
int behind)
{
sector_t sectors = bad->len;
sector_t s = bad->start;
u64 *p = bb->page;
int merged = 0;
WARN_ON(s >= BB_OFFSET(p[behind]));
WARN_ON((s + sectors) < BB_OFFSET(p[behind]));
if (s < BB_OFFSET(p[behind])) {
merged = BB_OFFSET(p[behind]) - s;
p[behind] = BB_MAKE(s, BB_LEN(p[behind]) + merged, bad->ack);
WARN_ON((BB_LEN(p[behind]) + merged) >= BB_MAX_LEN);
}
return merged;
}
/*
* Return 'true' if the range indicated by 'bad' can be forward
* merged with the bad range (from the bad table) indexed by 'prev'.
*/
static bool can_merge_front(struct badblocks *bb, int prev,
struct badblocks_context *bad)
{
sector_t s = bad->start;
u64 *p = bb->page;
if (BB_ACK(p[prev]) == bad->ack &&
(s < BB_END(p[prev]) ||
(s == BB_END(p[prev]) && (BB_LEN(p[prev]) < BB_MAX_LEN))))
return true;
return false;
}
/*
* Do forward merge for range indicated by 'bad' and the bad range
* (from bad table) indexed by 'prev'. The return value is sectors
* merged from bad->len.
*/
static int front_merge(struct badblocks *bb, int prev, struct badblocks_context *bad)
{
sector_t sectors = bad->len;
sector_t s = bad->start;
u64 *p = bb->page;
int merged = 0;
WARN_ON(s > BB_END(p[prev]));
if (s < BB_END(p[prev])) {
merged = min_t(sector_t, sectors, BB_END(p[prev]) - s);
} else {
merged = min_t(sector_t, sectors, BB_MAX_LEN - BB_LEN(p[prev]));
if ((prev + 1) < bb->count &&
merged > (BB_OFFSET(p[prev + 1]) - BB_END(p[prev]))) {
merged = BB_OFFSET(p[prev + 1]) - BB_END(p[prev]);
}
p[prev] = BB_MAKE(BB_OFFSET(p[prev]),
BB_LEN(p[prev]) + merged, bad->ack);
}
return merged;
}
/*
* 'Combine' is a special case which can_merge_front() is not able to
* handle: If a bad range (indexed by 'prev' from bad table) exactly
* starts as bad->start, and the bad range ahead of 'prev' (indexed by
* 'prev - 1' from bad table) exactly ends at where 'prev' starts, and
* the sum of their lengths does not exceed BB_MAX_LEN limitation, then
* these two bad range (from bad table) can be combined.
*
* Return 'true' if bad ranges indexed by 'prev' and 'prev - 1' from bad
* table can be combined.
*/
static bool can_combine_front(struct badblocks *bb, int prev,
struct badblocks_context *bad)
{
u64 *p = bb->page;
if ((prev > 0) &&
(BB_OFFSET(p[prev]) == bad->start) &&
(BB_END(p[prev - 1]) == BB_OFFSET(p[prev])) &&
(BB_LEN(p[prev - 1]) + BB_LEN(p[prev]) <= BB_MAX_LEN) &&
(BB_ACK(p[prev - 1]) == BB_ACK(p[prev])))
return true;
return false;
}
/*
* Combine the bad ranges indexed by 'prev' and 'prev - 1' (from bad
* table) into one larger bad range, and the new range is indexed by
* 'prev - 1'.
* The caller of front_combine() will decrease bb->count, therefore
* it is unnecessary to clear p[perv] after front merge.
*/
static void front_combine(struct badblocks *bb, int prev)
{
u64 *p = bb->page;
p[prev - 1] = BB_MAKE(BB_OFFSET(p[prev - 1]),
BB_LEN(p[prev - 1]) + BB_LEN(p[prev]),
BB_ACK(p[prev]));
if ((prev + 1) < bb->count)
memmove(p + prev, p + prev + 1, (bb->count - prev - 1) * 8);
}
/*
* Return 'true' if the range indicated by 'bad' is exactly forward
* overlapped with the bad range (from bad table) indexed by 'front'.
* Exactly forward overlap means the bad range (from bad table) indexed
* by 'prev' does not cover the whole range indicated by 'bad'.
*/
static bool overlap_front(struct badblocks *bb, int front,
struct badblocks_context *bad)
{
u64 *p = bb->page;
if (bad->start >= BB_OFFSET(p[front]) &&
bad->start < BB_END(p[front]))
return true;
return false;
}
/*
* Return 'true' if the range indicated by 'bad' is exactly backward
* overlapped with the bad range (from bad table) indexed by 'behind'.
*/
static bool overlap_behind(struct badblocks *bb, struct badblocks_context *bad,
int behind)
{
u64 *p = bb->page;
if (bad->start < BB_OFFSET(p[behind]) &&
(bad->start + bad->len) > BB_OFFSET(p[behind]))
return true;
return false;
}
/*
* Return 'true' if the range indicated by 'bad' can overwrite the bad
* range (from bad table) indexed by 'prev'.
*
* The range indicated by 'bad' can overwrite the bad range indexed by
* 'prev' when,
* 1) The whole range indicated by 'bad' can cover partial or whole bad
* range (from bad table) indexed by 'prev'.
* 2) The ack value of 'bad' is larger or equal to the ack value of bad
* range 'prev'.
*
* If the overwriting doesn't cover the whole bad range (from bad table)
* indexed by 'prev', new range might be split from existing bad range,
* 1) The overwrite covers head or tail part of existing bad range, 1
* extra bad range will be split and added into the bad table.
* 2) The overwrite covers middle of existing bad range, 2 extra bad
* ranges will be split (ahead and after the overwritten range) and
* added into the bad table.
* The number of extra split ranges of the overwriting is stored in
* 'extra' and returned for the caller.
*/
static bool can_front_overwrite(struct badblocks *bb, int prev,
struct badblocks_context *bad, int *extra)
{
u64 *p = bb->page;
int len;
WARN_ON(!overlap_front(bb, prev, bad));
if (BB_ACK(p[prev]) >= bad->ack)
return false;
if (BB_END(p[prev]) <= (bad->start + bad->len)) {
len = BB_END(p[prev]) - bad->start;
if (BB_OFFSET(p[prev]) == bad->start)
*extra = 0;
else
*extra = 1;
bad->len = len;
} else {
if (BB_OFFSET(p[prev]) == bad->start)
*extra = 1;
else
/*
* prev range will be split into two, beside the overwritten
* one, an extra slot needed from bad table.
*/
*extra = 2;
}
if ((bb->count + (*extra)) >= MAX_BADBLOCKS)
return false;
return true;
}
/*
* Do the overwrite from the range indicated by 'bad' to the bad range
* (from bad table) indexed by 'prev'.
* The previously called can_front_overwrite() will provide how many
* extra bad range(s) might be split and added into the bad table. All
* the splitting cases in the bad table will be handled here.
*/
static int front_overwrite(struct badblocks *bb, int prev,
struct badblocks_context *bad, int extra)
{
u64 *p = bb->page;
sector_t orig_end = BB_END(p[prev]);
int orig_ack = BB_ACK(p[prev]);
switch (extra) {
case 0:
p[prev] = BB_MAKE(BB_OFFSET(p[prev]), BB_LEN(p[prev]),
bad->ack);
break;
case 1:
if (BB_OFFSET(p[prev]) == bad->start) {
p[prev] = BB_MAKE(BB_OFFSET(p[prev]),
bad->len, bad->ack);
memmove(p + prev + 2, p + prev + 1,
(bb->count - prev - 1) * 8);
p[prev + 1] = BB_MAKE(bad->start + bad->len,
orig_end - BB_END(p[prev]),
orig_ack);
} else {
p[prev] = BB_MAKE(BB_OFFSET(p[prev]),
bad->start - BB_OFFSET(p[prev]),
orig_ack);
/*
* prev +2 -> prev + 1 + 1, which is for,
* 1) prev + 1: the slot index of the previous one
* 2) + 1: one more slot for extra being 1.
*/
memmove(p + prev + 2, p + prev + 1,
(bb->count - prev - 1) * 8);
p[prev + 1] = BB_MAKE(bad->start, bad->len, bad->ack);
}
break;
case 2:
p[prev] = BB_MAKE(BB_OFFSET(p[prev]),
bad->start - BB_OFFSET(p[prev]),
orig_ack);
/*
* prev + 3 -> prev + 1 + 2, which is for,
* 1) prev + 1: the slot index of the previous one
* 2) + 2: two more slots for extra being 2.
*/
memmove(p + prev + 3, p + prev + 1,
(bb->count - prev - 1) * 8);
p[prev + 1] = BB_MAKE(bad->start, bad->len, bad->ack);
p[prev + 2] = BB_MAKE(BB_END(p[prev + 1]),
orig_end - BB_END(p[prev + 1]),
orig_ack);
break;
default:
break;
}
return bad->len;
}
/*
* Explicitly insert a range indicated by 'bad' to the bad table, where
* the location is indexed by 'at'.
*/
static int insert_at(struct badblocks *bb, int at, struct badblocks_context *bad)
{
u64 *p = bb->page;
int len;
WARN_ON(badblocks_full(bb));
len = min_t(sector_t, bad->len, BB_MAX_LEN);
if (at < bb->count)
memmove(p + at + 1, p + at, (bb->count - at) * 8);
p[at] = BB_MAKE(bad->start, len, bad->ack);
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;
}
/*
* 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;
}
/* Do the exact work to check bad blocks range from the bad block table */
static int _badblocks_check(struct badblocks *bb, sector_t s, int sectors,
sector_t *first_bad, int *bad_sectors)
{
int unacked_badblocks, acked_badblocks;
int prev = -1, hint = -1, set = 0;
struct badblocks_context bad;
unsigned int seq;
int len, rv;
u64 *p;
WARN_ON(bb->shift < 0 || sectors == 0);
if (bb->shift > 0) {
sector_t target;
/* round the start down, and the end up */
target = s + sectors;
rounddown(s, bb->shift);
roundup(target, bb->shift);
sectors = target - s;
}
retry:
seq = read_seqbegin(&bb->lock);
p = bb->page;
unacked_badblocks = 0;
acked_badblocks = 0;
re_check:
bad.start = s;
bad.len = sectors;
if (badblocks_empty(bb)) {
len = sectors;
goto update_sectors;
}
prev = prev_badblocks(bb, &bad, hint);
/* start after all badblocks */
if ((prev >= 0) &&
((prev + 1) >= bb->count) && !overlap_front(bb, prev, &bad)) {
len = sectors;
goto update_sectors;
}
/* Overlapped with front badblocks record */
if ((prev >= 0) && overlap_front(bb, prev, &bad)) {
if (BB_ACK(p[prev]))
acked_badblocks++;
else
unacked_badblocks++;
if (BB_END(p[prev]) >= (s + sectors))
len = sectors;
else
len = BB_END(p[prev]) - s;
if (set == 0) {
*first_bad = BB_OFFSET(p[prev]);
*bad_sectors = BB_LEN(p[prev]);
set = 1;
}
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;
goto update_sectors;
}
/* not cover any badblocks range in the table */
len = sectors;
update_sectors:
s += len;
sectors -= len;
if (sectors > 0)
goto re_check;
WARN_ON(sectors < 0);
if (unacked_badblocks > 0)
rv = -1;
else if (acked_badblocks > 0)
rv = 1;
else
rv = 0;
if (read_seqretry(&bb->lock, seq))
goto retry;
return rv;
}
/**
* badblocks_check() - check a given range for bad sectors
* @bb: the badblocks structure that holds all badblock information
* @s: sector (start) at which to check for badblocks
* @sectors: number of sectors to check for badblocks
* @first_bad: pointer to store location of the first badblock
* @bad_sectors: pointer to store number of badblocks after @first_bad
*
* We can record which blocks on each device are 'bad' and so just
* fail those blocks, or that stripe, rather than the whole device.
* Entries in the bad-block table are 64bits wide. This comprises:
* Length of bad-range, in sectors: 0-511 for lengths 1-512
* Start of bad-range, sector offset, 54 bits (allows 8 exbibytes)
* A 'shift' can be set so that larger blocks are tracked and
* consequently larger devices can be covered.
* 'Acknowledged' flag - 1 bit. - the most significant bit.
*
* Locking of the bad-block table uses a seqlock so badblocks_check
* might need to retry if it is very unlucky.
* We will sometimes want to check for bad blocks in a bi_end_io function,
* so we use the write_seqlock_irq variant.
*
* When looking for a bad block we specify a range and want to
* know if any block in the range is bad. So we binary-search
* to the last range that starts at-or-before the given endpoint,
* (or "before the sector after the target range")
* then see if it ends after the given start.
*
* Return:
* 0: there are no known bad blocks in the range
* 1: there are known bad block which are all acknowledged
* -1: there are bad blocks which have not yet been acknowledged in metadata.
* plus the start/length of the first bad section we overlap.
*/
int badblocks_check(struct badblocks *bb, sector_t s, int sectors,
sector_t *first_bad, int *bad_sectors)
{
return _badblocks_check(bb, s, sectors, first_bad, bad_sectors);
}
EXPORT_SYMBOL_GPL(badblocks_check);
/**
* badblocks_set() - Add a range of bad blocks to the table.
* @bb: the badblocks structure that holds all badblock information
* @s: first sector to mark as bad
* @sectors: number of sectors to mark as bad
* @acknowledged: weather to mark the bad sectors as acknowledged
*
* This might extend the table, or might contract it if two adjacent ranges
* can be merged. We binary-search to find the 'insertion' point, then
* decide how best to handle it.
*
* Return:
* 0: success
* 1: failed to set badblocks (out of space)
*/
int badblocks_set(struct badblocks *bb, sector_t s, int sectors,
int acknowledged)
{
return _badblocks_set(bb, s, sectors, acknowledged);
}
EXPORT_SYMBOL_GPL(badblocks_set);
/**
* badblocks_clear() - Remove a range of bad blocks to the table.
* @bb: the badblocks structure that holds all badblock information
* @s: first sector to mark as bad
* @sectors: number of sectors to mark as bad
*
* This may involve extending the table if we spilt a region,
* but it must not fail. So if the table becomes full, we just
* drop the remove request.
*
* Return:
* 0: success
* 1: failed to clear badblocks
*/
int badblocks_clear(struct badblocks *bb, sector_t s, int sectors)
{
return _badblocks_clear(bb, s, sectors);
}
EXPORT_SYMBOL_GPL(badblocks_clear);
/**
* ack_all_badblocks() - Acknowledge all bad blocks in a list.
* @bb: the badblocks structure that holds all badblock information
*
* This only succeeds if ->changed is clear. It is used by
* in-kernel metadata updates
*/
void ack_all_badblocks(struct badblocks *bb)
{
if (bb->page == NULL || bb->changed)
/* no point even trying */
return;
write_seqlock_irq(&bb->lock);
if (bb->changed == 0 && bb->unacked_exist) {
u64 *p = bb->page;
int i;
for (i = 0; i < bb->count ; i++) {
if (!BB_ACK(p[i])) {
sector_t start = BB_OFFSET(p[i]);
int len = BB_LEN(p[i]);
p[i] = BB_MAKE(start, len, 1);
}
}
bb->unacked_exist = 0;
}
write_sequnlock_irq(&bb->lock);
}
EXPORT_SYMBOL_GPL(ack_all_badblocks);
/**
* badblocks_show() - sysfs access to bad-blocks list
* @bb: the badblocks structure that holds all badblock information
* @page: buffer received from sysfs
* @unack: weather to show unacknowledged badblocks
*
* Return:
* Length of returned data
*/
ssize_t badblocks_show(struct badblocks *bb, char *page, int unack)
{
size_t len;
int i;
u64 *p = bb->page;
unsigned seq;
if (bb->shift < 0)
return 0;
retry:
seq = read_seqbegin(&bb->lock);
len = 0;
i = 0;
while (len < PAGE_SIZE && i < bb->count) {
sector_t s = BB_OFFSET(p[i]);
unsigned int length = BB_LEN(p[i]);
int ack = BB_ACK(p[i]);
i++;
if (unack && ack)
continue;
len += snprintf(page+len, PAGE_SIZE-len, "%llu %u\n",
(unsigned long long)s << bb->shift,
length << bb->shift);
}
if (unack && len == 0)
bb->unacked_exist = 0;
if (read_seqretry(&bb->lock, seq))
goto retry;
return len;
}
EXPORT_SYMBOL_GPL(badblocks_show);
/**
* badblocks_store() - sysfs access to bad-blocks list
* @bb: the badblocks structure that holds all badblock information
* @page: buffer received from sysfs
* @len: length of data received from sysfs
* @unack: weather to show unacknowledged badblocks
*
* Return:
* Length of the buffer processed or -ve error.
*/
ssize_t badblocks_store(struct badblocks *bb, const char *page, size_t len,
int unack)
{
unsigned long long sector;
int length;
char newline;
switch (sscanf(page, "%llu %d%c", §or, &length, &newline)) {
case 3:
if (newline != '\n')
return -EINVAL;
fallthrough;
case 2:
if (length <= 0)
return -EINVAL;
break;
default:
return -EINVAL;
}
if (badblocks_set(bb, sector, length, !unack))
return -ENOSPC;
else
return len;
}
EXPORT_SYMBOL_GPL(badblocks_store);
static int __badblocks_init(struct device *dev, struct badblocks *bb,
int enable)
{
bb->dev = dev;
bb->count = 0;
if (enable)
bb->shift = 0;
else
bb->shift = -1;
if (dev)
bb->page = devm_kzalloc(dev, PAGE_SIZE, GFP_KERNEL);
else
bb->page = kzalloc(PAGE_SIZE, GFP_KERNEL);
if (!bb->page) {
bb->shift = -1;
return -ENOMEM;
}
seqlock_init(&bb->lock);
return 0;
}
/**
* badblocks_init() - initialize the badblocks structure
* @bb: the badblocks structure that holds all badblock information
* @enable: weather to enable badblocks accounting
*
* Return:
* 0: success
* -ve errno: on error
*/
int badblocks_init(struct badblocks *bb, int enable)
{
return __badblocks_init(NULL, bb, enable);
}
EXPORT_SYMBOL_GPL(badblocks_init);
int devm_init_badblocks(struct device *dev, struct badblocks *bb)
{
if (!bb)
return -EINVAL;
return __badblocks_init(dev, bb, 1);
}
EXPORT_SYMBOL_GPL(devm_init_badblocks);
/**
* badblocks_exit() - free the badblocks structure
* @bb: the badblocks structure that holds all badblock information
*/
void badblocks_exit(struct badblocks *bb)
{
if (!bb)
return;
if (bb->dev)
devm_kfree(bb->dev, bb->page);
else
kfree(bb->page);
bb->page = NULL;
}
EXPORT_SYMBOL_GPL(badblocks_exit);
