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Subject[PATCH 4.4 103/107] ubi: Rework Fastmap attach base code
Date
4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Richard Weinberger <richard@nod.at>

commit fdf10ed710c0aa177e8dfcd84e65e4e5e8e0956b upstream.

Introduce a new list to the UBI attach information
object to be able to deal better with old and corrupted
Fastmap eraseblocks.
Also move more Fastmap specific code into fastmap.c.

Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/mtd/ubi/attach.c | 99 ++++++++++++++++++++++++++++++++--------------
drivers/mtd/ubi/fastmap.c | 36 +++++++++++++++-
drivers/mtd/ubi/ubi.h | 28 ++++++++++++-
drivers/mtd/ubi/wl.c | 41 +++++++++++++++----
4 files changed, 162 insertions(+), 42 deletions(-)

--- a/drivers/mtd/ubi/attach.c
+++ b/drivers/mtd/ubi/attach.c
@@ -175,6 +175,40 @@ static int add_corrupted(struct ubi_atta
}

/**
+ * add_fastmap - add a Fastmap related physical eraseblock.
+ * @ai: attaching information
+ * @pnum: physical eraseblock number the VID header came from
+ * @vid_hdr: the volume identifier header
+ * @ec: erase counter of the physical eraseblock
+ *
+ * This function allocates a 'struct ubi_ainf_peb' object for a Fastamp
+ * physical eraseblock @pnum and adds it to the 'fastmap' list.
+ * Such blocks can be Fastmap super and data blocks from both the most
+ * recent Fastmap we're attaching from or from old Fastmaps which will
+ * be erased.
+ */
+static int add_fastmap(struct ubi_attach_info *ai, int pnum,
+ struct ubi_vid_hdr *vid_hdr, int ec)
+{
+ struct ubi_ainf_peb *aeb;
+
+ aeb = kmem_cache_alloc(ai->aeb_slab_cache, GFP_KERNEL);
+ if (!aeb)
+ return -ENOMEM;
+
+ aeb->pnum = pnum;
+ aeb->vol_id = be32_to_cpu(vidh->vol_id);
+ aeb->sqnum = be64_to_cpu(vidh->sqnum);
+ aeb->ec = ec;
+ list_add(&aeb->u.list, &ai->fastmap);
+
+ dbg_bld("add to fastmap list: PEB %d, vol_id %d, sqnum: %llu", pnum,
+ aeb->vol_id, aeb->sqnum);
+
+ return 0;
+}
+
+/**
* validate_vid_hdr - check volume identifier header.
* @ubi: UBI device description object
* @vid_hdr: the volume identifier header to check
@@ -822,18 +856,15 @@ static bool vol_ignored(int vol_id)
* @ubi: UBI device description object
* @ai: attaching information
* @pnum: the physical eraseblock number
- * @vid: The volume ID of the found volume will be stored in this pointer
- * @sqnum: The sqnum of the found volume will be stored in this pointer
*
* This function reads UBI headers of PEB @pnum, checks them, and adds
* information about this PEB to the corresponding list or RB-tree in the
* "attaching info" structure. Returns zero if the physical eraseblock was
* successfully handled and a negative error code in case of failure.
*/
-static int scan_peb(struct ubi_device *ubi, struct ubi_attach_info *ai,
- int pnum, int *vid, unsigned long long *sqnum)
+static int scan_peb(struct ubi_device *ubi, struct ubi_attach_info *ai, int pnum)
{
- long long uninitialized_var(ec);
+ long long ec;
int err, bitflips = 0, vol_id = -1, ec_err = 0;

dbg_bld("scan PEB %d", pnum);
@@ -1005,10 +1036,6 @@ static int scan_peb(struct ubi_device *u
}

vol_id = be32_to_cpu(vidh->vol_id);
- if (vid)
- *vid = vol_id;
- if (sqnum)
- *sqnum = be64_to_cpu(vidh->sqnum);
if (vol_id > UBI_MAX_VOLUMES && !vol_ignored(vol_id)) {
int lnum = be32_to_cpu(vidh->lnum);

@@ -1049,7 +1076,12 @@ static int scan_peb(struct ubi_device *u
if (ec_err)
ubi_warn(ubi, "valid VID header but corrupted EC header at PEB %d",
pnum);
- err = ubi_add_to_av(ubi, ai, pnum, ec, vidh, bitflips);
+
+ if (ubi_is_fm_vol(vol_id))
+ err = add_fastmap(ai, pnum, vidh, ec);
+ else
+ err = ubi_add_to_av(ubi, ai, pnum, ec, vidh, bitflips);
+
if (err)
return err;

@@ -1198,6 +1230,10 @@ static void destroy_ai(struct ubi_attach
list_del(&aeb->u.list);
kmem_cache_free(ai->aeb_slab_cache, aeb);
}
+ list_for_each_entry_safe(aeb, aeb_tmp, &ai->fastmap, u.list) {
+ list_del(&aeb->u.list);
+ kmem_cache_free(ai->aeb_slab_cache, aeb);
+ }

/* Destroy the volume RB-tree */
rb = ai->volumes.rb_node;
@@ -1257,7 +1293,7 @@ static int scan_all(struct ubi_device *u
cond_resched();

dbg_gen("process PEB %d", pnum);
- err = scan_peb(ubi, ai, pnum, NULL, NULL);
+ err = scan_peb(ubi, ai, pnum);
if (err < 0)
goto out_vidh;
}
@@ -1323,6 +1359,7 @@ static struct ubi_attach_info *alloc_ai(
INIT_LIST_HEAD(&ai->free);
INIT_LIST_HEAD(&ai->erase);
INIT_LIST_HEAD(&ai->alien);
+ INIT_LIST_HEAD(&ai->fastmap);
ai->volumes = RB_ROOT;
ai->aeb_slab_cache = kmem_cache_create("ubi_aeb_slab_cache",
sizeof(struct ubi_ainf_peb),
@@ -1349,52 +1386,54 @@ static struct ubi_attach_info *alloc_ai(
*/
static int scan_fast(struct ubi_device *ubi, struct ubi_attach_info **ai)
{
- int err, pnum, fm_anchor = -1;
- unsigned long long max_sqnum = 0;
+ int err, pnum;
+ struct ubi_attach_info *scan_ai;

err = -ENOMEM;

+ scan_ai = alloc_ai();
+ if (!scan_ai)
+ goto out;
+
ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
if (!ech)
- goto out;
+ goto out_ai;

vidh = ubi_zalloc_vid_hdr(ubi, GFP_KERNEL);
if (!vidh)
goto out_ech;

for (pnum = 0; pnum < UBI_FM_MAX_START; pnum++) {
- int vol_id = -1;
- unsigned long long sqnum = -1;
cond_resched();

dbg_gen("process PEB %d", pnum);
- err = scan_peb(ubi, *ai, pnum, &vol_id, &sqnum);
+ err = scan_peb(ubi, scan_ai, pnum);
if (err < 0)
goto out_vidh;
-
- if (vol_id == UBI_FM_SB_VOLUME_ID && sqnum > max_sqnum) {
- max_sqnum = sqnum;
- fm_anchor = pnum;
- }
}

ubi_free_vid_hdr(ubi, vidh);
kfree(ech);

- if (fm_anchor < 0)
- return UBI_NO_FASTMAP;
-
- destroy_ai(*ai);
- *ai = alloc_ai();
- if (!*ai)
- return -ENOMEM;
+ err = ubi_scan_fastmap(ubi, *ai, scan_ai);
+ if (err) {
+ /*
+ * Didn't attach via fastmap, do a full scan but reuse what
+ * we've aready scanned.
+ */
+ destroy_ai(*ai);
+ *ai = scan_ai;
+ } else
+ destroy_ai(scan_ai);

- return ubi_scan_fastmap(ubi, *ai, fm_anchor);
+ return err;

out_vidh:
ubi_free_vid_hdr(ubi, vidh);
out_ech:
kfree(ech);
+out_ai:
+ destroy_ai(scan_ai);
out:
return err;
}
--- a/drivers/mtd/ubi/fastmap.c
+++ b/drivers/mtd/ubi/fastmap.c
@@ -851,27 +851,57 @@ fail:
}

/**
+ * find_fm_anchor - find the most recent Fastmap superblock (anchor)
+ * @ai: UBI attach info to be filled
+ */
+static int find_fm_anchor(struct ubi_attach_info *ai)
+{
+ int ret = -1;
+ struct ubi_ainf_peb *aeb;
+ unsigned long long max_sqnum = 0;
+
+ list_for_each_entry(aeb, &ai->fastmap, u.list) {
+ if (aeb->vol_id == UBI_FM_SB_VOLUME_ID && aeb->sqnum > max_sqnum) {
+ max_sqnum = aeb->sqnum;
+ ret = aeb->pnum;
+ }
+ }
+
+ return ret;
+}
+
+/**
* ubi_scan_fastmap - scan the fastmap.
* @ubi: UBI device object
* @ai: UBI attach info to be filled
- * @fm_anchor: The fastmap starts at this PEB
+ * @scan_ai: UBI attach info from the first 64 PEBs,
+ * used to find the most recent Fastmap data structure
*
* Returns 0 on success, UBI_NO_FASTMAP if no fastmap was found,
* UBI_BAD_FASTMAP if one was found but is not usable.
* < 0 indicates an internal error.
*/
int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai,
- int fm_anchor)
+ struct ubi_attach_info *scan_ai)
{
struct ubi_fm_sb *fmsb, *fmsb2;
struct ubi_vid_hdr *vh;
struct ubi_ec_hdr *ech;
struct ubi_fastmap_layout *fm;
- int i, used_blocks, pnum, ret = 0;
+ struct ubi_ainf_peb *tmp_aeb, *aeb;
+ int i, used_blocks, pnum, fm_anchor, ret = 0;
size_t fm_size;
__be32 crc, tmp_crc;
unsigned long long sqnum = 0;

+ fm_anchor = find_fm_anchor(scan_ai);
+ if (fm_anchor < 0)
+ return UBI_NO_FASTMAP;
+
+ /* Move all (possible) fastmap blocks into our new attach structure. */
+ list_for_each_entry_safe(aeb, tmp_aeb, &scan_ai->fastmap, u.list)
+ list_move_tail(&aeb->u.list, &ai->fastmap);
+
down_write(&ubi->fm_protect);
memset(ubi->fm_buf, 0, ubi->fm_size);

--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -699,6 +699,8 @@ struct ubi_ainf_volume {
* @erase: list of physical eraseblocks which have to be erased
* @alien: list of physical eraseblocks which should not be used by UBI (e.g.,
* those belonging to "preserve"-compatible internal volumes)
+ * @fastmap: list of physical eraseblocks which relate to fastmap (e.g.,
+ * eraseblocks of the current and not yet erased old fastmap blocks)
* @corr_peb_count: count of PEBs in the @corr list
* @empty_peb_count: count of PEBs which are presumably empty (contain only
* 0xFF bytes)
@@ -727,6 +729,7 @@ struct ubi_attach_info {
struct list_head free;
struct list_head erase;
struct list_head alien;
+ struct list_head fastmap;
int corr_peb_count;
int empty_peb_count;
int alien_peb_count;
@@ -907,7 +910,7 @@ int ubi_compare_lebs(struct ubi_device *
size_t ubi_calc_fm_size(struct ubi_device *ubi);
int ubi_update_fastmap(struct ubi_device *ubi);
int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai,
- int fm_anchor);
+ struct ubi_attach_info *scan_ai);
#else
static inline int ubi_update_fastmap(struct ubi_device *ubi) { return 0; }
#endif
@@ -1116,4 +1119,27 @@ static inline bool ubi_is_fm_vol(int vol
return false;
}

+/**
+ * ubi_find_fm_block - check whether a PEB is part of the current Fastmap.
+ * @ubi: UBI device description object
+ * @pnum: physical eraseblock to look for
+ *
+ * This function returns a wear leveling object if @pnum relates to the current
+ * fastmap, @NULL otherwise.
+ */
+static inline struct ubi_wl_entry *ubi_find_fm_block(const struct ubi_device *ubi,
+ int pnum)
+{
+ int i;
+
+ if (ubi->fm) {
+ for (i = 0; i < ubi->fm->used_blocks; i++) {
+ if (ubi->fm->e[i]->pnum == pnum)
+ return ubi->fm->e[i];
+ }
+ }
+
+ return NULL;
+}
+
#endif /* !__UBI_UBI_H__ */
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -1598,19 +1598,44 @@ int ubi_wl_init(struct ubi_device *ubi,
}
}

- dbg_wl("found %i PEBs", found_pebs);
+ list_for_each_entry(aeb, &ai->fastmap, u.list) {
+ cond_resched();
+
+ e = ubi_find_fm_block(ubi, aeb->pnum);
+
+ if (e) {
+ ubi_assert(!ubi->lookuptbl[e->pnum]);
+ ubi->lookuptbl[e->pnum] = e;
+ } else {
+ /*
+ * Usually old Fastmap PEBs are scheduled for erasure
+ * and we don't have to care about them but if we face
+ * an power cut before scheduling them we need to
+ * take care of them here.
+ */
+ if (ubi->lookuptbl[aeb->pnum])
+ continue;

- if (ubi->fm) {
- ubi_assert(ubi->good_peb_count ==
- found_pebs + ubi->fm->used_blocks);
+ e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL);
+ if (!e)
+ goto out_free;

- for (i = 0; i < ubi->fm->used_blocks; i++) {
- e = ubi->fm->e[i];
+ e->pnum = aeb->pnum;
+ e->ec = aeb->ec;
+ ubi_assert(!ubi->lookuptbl[e->pnum]);
ubi->lookuptbl[e->pnum] = e;
+ if (schedule_erase(ubi, e, aeb->vol_id, aeb->lnum, 0)) {
+ wl_entry_destroy(ubi, e);
+ goto out_free;
+ }
}
+
+ found_pebs++;
}
- else
- ubi_assert(ubi->good_peb_count == found_pebs);
+
+ dbg_wl("found %i PEBs", found_pebs);
+
+ ubi_assert(ubi->good_peb_count == found_pebs);

reserved_pebs = WL_RESERVED_PEBS;
ubi_fastmap_init(ubi, &reserved_pebs);

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