/* * Swap block device support for MTDs * Turns an MTD device into a swap device with block wear leveling * * Copyright © 2007,2011 Nokia Corporation. All rights reserved. * * Authors: Jarkko Lavinen <jarkko.lavinen@nokia.com> * * Based on Richard Purdie's earlier implementation in 2007. Background * support and lock-less operation written by Adrian Hunter. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * version 2 as published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA * 02110-1301 USA */ #include <linux/kernel.h> #include <linux/module.h> #include <linux/mtd/mtd.h> #include <linux/mtd/blktrans.h> #include <linux/rbtree.h> #include <linux/sched.h> #include <linux/slab.h> #include <linux/vmalloc.h> #include <linux/genhd.h> #include <linux/swap.h> #include <linux/debugfs.h> #include <linux/seq_file.h> #include <linux/device.h> #include <linux/math64.h> #define MTDSWAP_PREFIX "mtdswap" /* * The number of free eraseblocks when GC should stop */ #define CLEAN_BLOCK_THRESHOLD 20 /* * Number of free eraseblocks below which GC can also collect low frag * blocks. */ #define LOW_FRAG_GC_TRESHOLD 5 /* * Wear level cost amortization. We want to do wear leveling on the background * without disturbing gc too much. This is made by defining max GC frequency. * Frequency value 6 means 1/6 of the GC passes will pick an erase block based * on the biggest wear difference rather than the biggest dirtiness. * * The lower freq2 should be chosen so that it makes sure the maximum erase * difference will decrease even if a malicious application is deliberately * trying to make erase differences large. */ #define MAX_ERASE_DIFF 4000 #define COLLECT_NONDIRTY_BASE MAX_ERASE_DIFF #define COLLECT_NONDIRTY_FREQ1 6 #define COLLECT_NONDIRTY_FREQ2 4 #define PAGE_UNDEF UINT_MAX #define BLOCK_UNDEF UINT_MAX #define BLOCK_ERROR (UINT_MAX - 1) #define BLOCK_MAX (UINT_MAX - 2) #define EBLOCK_BAD (1 << 0) #define EBLOCK_NOMAGIC (1 << 1) #define EBLOCK_BITFLIP (1 << 2) #define EBLOCK_FAILED (1 << 3) #define EBLOCK_READERR (1 << 4) #define EBLOCK_IDX_SHIFT 5 struct swap_eb { struct rb_node rb; struct rb_root *root; unsigned int flags; unsigned int active_count; unsigned int erase_count; unsigned int pad; /* speeds up pointer decremtnt */ }; #define MTDSWAP_ECNT_MIN(rbroot) (rb_entry(rb_first(rbroot), struct swap_eb, \ rb)->erase_count) #define MTDSWAP_ECNT_MAX(rbroot) (rb_entry(rb_last(rbroot), struct swap_eb, \ rb)->erase_count) struct mtdswap_tree { struct rb_root root; unsigned int count; }; enum { MTDSWAP_CLEAN, MTDSWAP_USED, MTDSWAP_LOWFRAG, MTDSWAP_HIFRAG, MTDSWAP_DIRTY, MTDSWAP_BITFLIP, MTDSWAP_FAILING, MTDSWAP_TREE_CNT, }; struct mtdswap_dev { struct mtd_blktrans_dev *mbd_dev; struct mtd_info *mtd; struct device *dev; unsigned int *page_data; unsigned int *revmap; unsigned int eblks; unsigned int spare_eblks; unsigned int pages_per_eblk; unsigned int max_erase_count; struct swap_eb *eb_data; struct mtdswap_tree trees[MTDSWAP_TREE_CNT]; unsigned long long sect_read_count; unsigned long long sect_write_count; unsigned long long mtd_write_count; unsigned long long mtd_read_count; unsigned long long discard_count; unsigned long long discard_page_count; unsigned int curr_write_pos; struct swap_eb *curr_write; char *page_buf; char *oob_buf; struct dentry *debugfs_root; }; struct mtdswap_oobdata { __le16 magic; __le32 count; } __attribute__((packed)); #define MTDSWAP_MAGIC_CLEAN 0x2095 #define MTDSWAP_MAGIC_DIRTY (MTDSWAP_MAGIC_CLEAN + 1) #define MTDSWAP_TYPE_CLEAN 0 #define MTDSWAP_TYPE_DIRTY 1 #define MTDSWAP_OOBSIZE sizeof(struct mtdswap_oobdata) #define MTDSWAP_ERASE_RETRIES 3 /* Before marking erase block bad */ #define MTDSWAP_IO_RETRIES 3 enum { MTDSWAP_SCANNED_CLEAN, MTDSWAP_SCANNED_DIRTY, MTDSWAP_SCANNED_BITFLIP, MTDSWAP_SCANNED_BAD, }; /* * In the worst case mtdswap_writesect() has allocated the last clean * page from the current block and is then pre-empted by the GC * thread. The thread can consume a full erase block when moving a * block. */ #define MIN_SPARE_EBLOCKS 2 #define MIN_ERASE_BLOCKS (MIN_SPARE_EBLOCKS + 1) #define TREE_ROOT(d, name) (&d->trees[MTDSWAP_ ## name].root) #define TREE_EMPTY(d, name) (TREE_ROOT(d, name)->rb_node == NULL) #define TREE_NONEMPTY(d, name) (!TREE_EMPTY(d, name)) #define TREE_COUNT(d, name) (d->trees[MTDSWAP_ ## name].count) #define MTDSWAP_MBD_TO_MTDSWAP(dev) ((struct mtdswap_dev *)dev->priv) static char partitions[128] = ""; module_param_string(partitions, partitions, sizeof(partitions), 0444); MODULE_PARM_DESC(partitions, "MTD partition numbers to use as swap " "partitions=\"1,3,5\""); static unsigned int spare_eblocks = 10; module_param(spare_eblocks, uint, 0444); MODULE_PARM_DESC(spare_eblocks, "Percentage of spare erase blocks for " "garbage collection (default 10%)"); static bool header; /* false */ module_param(header, bool, 0444); MODULE_PARM_DESC(header, "Include builtin swap header (default 0, without header)"); static int mtdswap_gc(struct mtdswap_dev *d, unsigned int background); static loff_t mtdswap_eb_offset(struct mtdswap_dev *d, struct swap_eb *eb) { return (loff_t)(eb - d->eb_data) * d->mtd->erasesize; } static void mtdswap_eb_detach(struct mtdswap_dev *d, struct swap_eb *eb) { unsigned int oldidx; struct mtdswap_tree *tp; if (eb->root) { tp = container_of(eb->root, struct mtdswap_tree, root); oldidx = tp - &d->trees[0]; d->trees[oldidx].count--; rb_erase(&eb->rb, eb->root); } } static void __mtdswap_rb_add(struct rb_root *root, struct swap_eb *eb) { struct rb_node **p, *parent = NULL; struct swap_eb *cur; p = &root->rb_node; while (*p) { parent = *p; cur = rb_entry(parent, struct swap_eb, rb); if (eb->erase_count > cur->erase_count) p = &(*p)->rb_right; else p = &(*p)->rb_left; } rb_link_node(&eb->rb, parent, p); rb_insert_color(&eb->rb, root); } static void mtdswap_rb_add(struct mtdswap_dev *d, struct swap_eb *eb, int idx) { struct rb_root *root; if (eb->root == &d->trees[idx].root) return; mtdswap_eb_detach(d, eb); root = &d->trees[idx].root; __mtdswap_rb_add(root, eb); eb->root = root; d->trees[idx].count++; } static struct rb_node *mtdswap_rb_index(struct rb_root *root, unsigned int idx) { struct rb_node *p; unsigned int i; p = rb_first(root); i = 0; while (i < idx && p) { p = rb_next(p); i++; } return p; } static int mtdswap_handle_badblock(struct mtdswap_dev *d, struct swap_eb *eb) { int ret; loff_t offset; d->spare_eblks--; eb->flags |= EBLOCK_BAD; mtdswap_eb_detach(d, eb); eb->root = NULL; /* badblocks not supported */ if (!d->mtd->block_markbad) return 1; offset = mtdswap_eb_offset(d, eb); dev_warn(d->dev, "Marking bad block at %08llx\n", offset); ret = d->mtd->block_markbad(d->mtd, offset); if (ret) { dev_warn(d->dev, "Mark block bad failed for block at %08llx " "error %d\n", offset, ret); return ret; } return 1; } static int mtdswap_handle_write_error(struct mtdswap_dev *d, struct swap_eb *eb) { unsigned int marked = eb->flags & EBLOCK_FAILED; struct swap_eb *curr_write = d->curr_write; eb->flags |= EBLOCK_FAILED; if (curr_write == eb) { d->curr_write = NULL; if (!marked && d->curr_write_pos != 0) { mtdswap_rb_add(d, eb, MTDSWAP_FAILING); return 0; } } return mtdswap_handle_badblock(d, eb); } static int mtdswap_read_oob(struct mtdswap_dev *d, loff_t from, struct mtd_oob_ops *ops) { int ret = d->mtd->read_oob(d->mtd, from, ops); if (ret == -EUCLEAN) return ret; if (ret) { dev_warn(d->dev, "Read OOB failed %d for block at %08llx\n", ret, from); return ret; } if (ops->oobretlen < ops->ooblen) { dev_warn(d->dev, "Read OOB return short read (%zd bytes not " "%zd) for block at %08llx\n", ops->oobretlen, ops->ooblen, from); return -EIO; } return 0; } static int mtdswap_read_markers(struct mtdswap_dev *d, struct swap_eb *eb) { struct mtdswap_oobdata *data, *data2; int ret; loff_t offset; struct mtd_oob_ops ops; offset = mtdswap_eb_offset(d, eb); /* Check first if the block is bad. */ if (d->mtd->block_isbad && d->mtd->block_isbad(d->mtd, offset)) return MTDSWAP_SCANNED_BAD; ops.ooblen = 2 * d->mtd->ecclayout->oobavail; ops.oobbuf = d->oob_buf; ops.ooboffs = 0; ops.datbuf = NULL; ops.mode = MTD_OOB_AUTO; ret = mtdswap_read_oob(d, offset, &ops); if (ret && ret != -EUCLEAN) return ret; data = (struct mtdswap_oobdata *)d->oob_buf; data2 = (struct mtdswap_oobdata *) (d->oob_buf + d->mtd->ecclayout->oobavail); if (le16_to_cpu(data->magic) == MTDSWAP_MAGIC_CLEAN) { eb->erase_count = le32_to_cpu(data->count); if (ret == -EUCLEAN) ret = MTDSWAP_SCANNED_BITFLIP; else { if (le16_to_cpu(data2->magic) == MTDSWAP_MAGIC_DIRTY) ret = MTDSWAP_SCANNED_DIRTY; else ret = MTDSWAP_SCANNED_CLEAN; } } else { eb->flags |= EBLOCK_NOMAGIC; ret = MTDSWAP_SCANNED_DIRTY; } return ret; } static int mtdswap_write_marker(struct mtdswap_dev *d, struct swap_eb *eb, u16 marker) { struct mtdswap_oobdata n; int ret; loff_t offset; struct mtd_oob_ops ops; ops.ooboffs = 0; ops.oobbuf = (uint8_t *)&n; ops.mode = MTD_OOB_AUTO; ops.datbuf = NULL; if (marker == MTDSWAP_TYPE_CLEAN) { n.magic = cpu_to_le16(MTDSWAP_MAGIC_CLEAN); n.count = cpu_to_le32(eb->erase_count); ops.ooblen = MTDSWAP_OOBSIZE; offset = mtdswap_eb_offset(d, eb); } else { n.magic = cpu_to_le16(MTDSWAP_MAGIC_DIRTY); ops.ooblen = sizeof(n.magic); offset = mtdswap_eb_offset(d, eb) + d->mtd->writesize; } ret = d->mtd->write_oob(d->mtd, offset , &ops); if (ret) { dev_warn(d->dev, "Write OOB failed for block at %08llx " "error %d\n", offset, ret); if (ret == -EIO || ret == -EBADMSG) mtdswap_handle_write_error(d, eb); return ret; } if (ops.oobretlen != ops.ooblen) { dev_warn(d->dev, "Short OOB write for block at %08llx: " "%zd not %zd\n", offset, ops.oobretlen, ops.ooblen); return ret; } return 0; } /* * Are there any erase blocks without MAGIC_CLEAN header, presumably * because power was cut off after erase but before header write? We * need to guestimate the erase count. */ static void mtdswap_check_counts(struct mtdswap_dev *d) { struct rb_root hist_root = RB_ROOT; struct rb_node *medrb; struct swap_eb *eb; unsigned int i, cnt, median; cnt = 0; for (i = 0; i < d->eblks; i++) { eb = d->eb_data + i; if (eb->flags & (EBLOCK_NOMAGIC | EBLOCK_BAD | EBLOCK_READERR)) continue; __mtdswap_rb_add(&hist_root, eb); cnt++; } if (cnt == 0) return; medrb = mtdswap_rb_index(&hist_root, cnt / 2); median = rb_entry(medrb, struct swap_eb, rb)->erase_count; d->max_erase_count = MTDSWAP_ECNT_MAX(&hist_root); for (i = 0; i < d->eblks; i++) { eb = d->eb_data + i; if (eb->flags & (EBLOCK_NOMAGIC | EBLOCK_READERR)) eb->erase_count = median; if (eb->flags & (EBLOCK_NOMAGIC | EBLOCK_BAD | EBLOCK_READERR)) continue; rb_erase(&eb->rb, &hist_root); } } static void mtdswap_scan_eblks(struct mtdswap_dev *d) { int status; unsigned int i, idx; struct swap_eb *eb; for (i = 0; i < d->eblks; i++) { eb = d->eb_data + i; status = mtdswap_read_markers(d, eb); if (status < 0) eb->flags |= EBLOCK_READERR; else if (status == MTDSWAP_SCANNED_BAD) { eb->flags |= EBLOCK_BAD; continue; } switch (status) { case MTDSWAP_SCANNED_CLEAN: idx = MTDSWAP_CLEAN; break; case MTDSWAP_SCANNED_DIRTY: case MTDSWAP_SCANNED_BITFLIP: idx = MTDSWAP_DIRTY; break; default: idx = MTDSWAP_FAILING; } eb->flags |= (idx << EBLOCK_IDX_SHIFT); } mtdswap_check_counts(d); for (i = 0; i < d->eblks; i++) { eb = d->eb_data + i; if (eb->flags & EBLOCK_BAD) continue; idx = eb->flags >> EBLOCK_IDX_SHIFT; mtdswap_rb_add(d, eb, idx); } } /* * Place eblk into a tree corresponding to its number of active blocks * it contains. */ static void mtdswap_store_eb(struct mtdswap_dev *d, struct swap_eb *eb) { unsigned int weight = eb->active_count; unsigned int maxweight = d->pages_per_eblk; if (eb == d->curr_write) return; if (eb->flags & EBLOCK_BITFLIP) mtdswap_rb_add(d, eb, MTDSWAP_BITFLIP); else if (eb->flags & (EBLOCK_READERR | EBLOCK_FAILED)) mtdswap_rb_add(d, eb, MTDSWAP_FAILING); if (weight == maxweight) mtdswap_rb_add(d, eb, MTDSWAP_USED); else if (weight == 0) mtdswap_rb_add(d, eb, MTDSWAP_DIRTY); else if (weight > (maxweight/2)) mtdswap_rb_add(d, eb, MTDSWAP_LOWFRAG); else mtdswap_rb_add(d, eb, MTDSWAP_HIFRAG); } static void mtdswap_erase_callback(struct erase_info *done) { wait_queue_head_t *wait_q = (wait_queue_head_t *)done->priv; wake_up(wait_q); } static int mtdswap_erase_block(struct mtdswap_dev *d, struct swap_eb *eb) { struct mtd_info *mtd = d->mtd; struct erase_info erase; wait_queue_head_t wq; unsigned int retries = 0; int ret; eb->erase_count++; if (eb->erase_count > d->max_erase_count) d->max_erase_count = eb->erase_count; retry: init_waitqueue_head(&wq); memset(&erase, 0, sizeof(struct erase_info)); erase.mtd = mtd; erase.callback = mtdswap_erase_callback; erase.addr = mtdswap_eb_offset(d, eb); erase.len = mtd->erasesize; erase.priv = (u_long)&wq; ret = mtd->erase(mtd, &erase); if (ret) { if (retries++ < MTDSWAP_ERASE_RETRIES) { dev_warn(d->dev, "erase of erase block %#llx on %s failed", erase.addr, mtd->name); yield(); goto retry; } dev_err(d->dev, "Cannot erase erase block %#llx on %s\n", erase.addr, mtd->name); mtdswap_handle_badblock(d, eb); return -EIO; } ret = wait_event_interruptible(wq, erase.state == MTD_ERASE_DONE || erase.state == MTD_ERASE_FAILED); if (ret) { dev_err(d->dev, "Interrupted erase block %#llx erassure on %s", erase.addr, mtd->name); return -EINTR; } if (erase.state == MTD_ERASE_FAILED) { if (retries++ < MTDSWAP_ERASE_RETRIES) { dev_warn(d->dev, "erase of erase block %#llx on %s failed", erase.addr, mtd->name); yield(); goto retry; } mtdswap_handle_badblock(d, eb); return -EIO; } return 0; } static int mtdswap_map_free_block(struct mtdswap_dev *d, unsigned int page, unsigned int *block) { int ret; struct swap_eb *old_eb = d->curr_write; struct rb_root *clean_root; struct swap_eb *eb; if (old_eb == NULL || d->curr_write_pos >= d->pages_per_eblk) { do { if (TREE_EMPTY(d, CLEAN)) return -ENOSPC; clean_root = TREE_ROOT(d, CLEAN); eb = rb_entry(rb_first(clean_root), struct swap_eb, rb); rb_erase(&eb->rb, clean_root); eb->root = NULL; TREE_COUNT(d, CLEAN)--; ret = mtdswap_write_marker(d, eb, MTDSWAP_TYPE_DIRTY); } while (ret == -EIO || ret == -EBADMSG); if (ret) return ret; d->curr_write_pos = 0; d->curr_write = eb; if (old_eb) mtdswap_store_eb(d, old_eb); } *block = (d->curr_write - d->eb_data) * d->pages_per_eblk + d->curr_write_pos; d->curr_write->active_count++; d->revmap[*block] = page; d->curr_write_pos++; return 0; } static unsigned int mtdswap_free_page_cnt(struct mtdswap_dev *d) { return TREE_COUNT(d, CLEAN) * d->pages_per_eblk + d->pages_per_eblk - d->curr_write_pos; } static unsigned int mtdswap_enough_free_pages(struct mtdswap_dev *d) { return mtdswap_free_page_cnt(d) > d->pages_per_eblk; } static int mtdswap_write_block(struct mtdswap_dev *d, char *buf, unsigned int page, unsigned int *bp, int gc_context) { struct mtd_info *mtd = d->mtd; struct swap_eb *eb; size_t retlen; loff_t writepos; int ret; retry: if (!gc_context) while (!mtdswap_enough_free_pages(d)) if (mtdswap_gc(d, 0) > 0) return -ENOSPC; ret = mtdswap_map_free_block(d, page, bp); eb = d->eb_data + (*bp / d->pages_per_eblk); if (ret == -EIO || ret == -EBADMSG) { d->curr_write = NULL; eb->active_count--; d->revmap[*bp] = PAGE_UNDEF; goto retry; } if (ret < 0) return ret; writepos = (loff_t)*bp << PAGE_SHIFT; ret = mtd->write(mtd, writepos, PAGE_SIZE, &retlen, buf); if (ret == -EIO || ret == -EBADMSG) { d->curr_write_pos--; eb->active_count--; d->revmap[*bp] = PAGE_UNDEF; mtdswap_handle_write_error(d, eb); goto retry; } if (ret < 0) { dev_err(d->dev, "Write to MTD device failed: %d (%zd written)", ret, retlen); goto err; } if (retlen != PAGE_SIZE) { dev_err(d->dev, "Short write to MTD device: %zd written", retlen); ret = -EIO; goto err; } return ret; err: d->curr_write_pos--; eb->active_count--; d->revmap[*bp] = PAGE_UNDEF; return ret; } static int mtdswap_move_block(struct mtdswap_dev *d, unsigned int oldblock, unsigned int *newblock) { struct mtd_info *mtd = d->mtd; struct swap_eb *eb, *oldeb; int ret; size_t retlen; unsigned int page, retries; loff_t readpos; page = d->revmap[oldblock]; readpos = (loff_t) oldblock << PAGE_SHIFT; retries = 0; retry: ret = mtd->read(mtd, readpos, PAGE_SIZE, &retlen, d->page_buf); if (ret < 0 && ret != -EUCLEAN) { oldeb = d->eb_data + oldblock / d->pages_per_eblk; oldeb->flags |= EBLOCK_READERR; dev_err(d->dev, "Read Error: %d (block %u)\n", ret, oldblock); retries++; if (retries < MTDSWAP_IO_RETRIES) goto retry; goto read_error; } if (retlen != PAGE_SIZE) { dev_err(d->dev, "Short read: %zd (block %u)\n", retlen, oldblock); ret = -EIO; goto read_error; } ret = mtdswap_write_block(d, d->page_buf, page, newblock, 1); if (ret < 0) { d->page_data[page] = BLOCK_ERROR; dev_err(d->dev, "Write error: %d\n", ret); return ret; } eb = d->eb_data + *newblock / d->pages_per_eblk; d->page_data[page] = *newblock; d->revmap[oldblock] = PAGE_UNDEF; eb = d->eb_data + oldblock / d->pages_per_eblk; eb->active_count--; return 0; read_error: d->page_data[page] = BLOCK_ERROR; d->revmap[oldblock] = PAGE_UNDEF; return ret; } static int mtdswap_gc_eblock(struct mtdswap_dev *d, struct swap_eb *eb) { unsigned int i, block, eblk_base, newblock; int ret, errcode; errcode = 0; eblk_base = (eb - d->eb_data) * d->pages_per_eblk; for (i = 0; i < d->pages_per_eblk; i++) { if (d->spare_eblks < MIN_SPARE_EBLOCKS) return -ENOSPC; block = eblk_base + i; if (d->revmap[block] == PAGE_UNDEF) continue; ret = mtdswap_move_block(d, block, &newblock); if (ret < 0 && !errcode) errcode = ret; } return errcode; } static int __mtdswap_choose_gc_tree(struct mtdswap_dev *d) { int idx, stopat; if (TREE_COUNT(d, CLEAN) < LOW_FRAG_GC_TRESHOLD) stopat = MTDSWAP_LOWFRAG; else stopat = MTDSWAP_HIFRAG; for (idx = MTDSWAP_BITFLIP; idx >= stopat; idx--) if (d->trees[idx].root.rb_node != NULL) return idx; return -1; } static int mtdswap_wlfreq(unsigned int maxdiff) { unsigned int h, x, y, dist, base; /* * Calculate linear ramp down from f1 to f2 when maxdiff goes from * MAX_ERASE_DIFF to MAX_ERASE_DIFF + COLLECT_NONDIRTY_BASE. Similar * to triangle with height f1 - f1 and width COLLECT_NONDIRTY_BASE. */ dist = maxdiff - MAX_ERASE_DIFF; if (dist > COLLECT_NONDIRTY_BASE) dist = COLLECT_NONDIRTY_BASE; /* * Modelling the slop as right angular triangle with base * COLLECT_NONDIRTY_BASE and height freq1 - freq2. The ratio y/x is * equal to the ratio h/base. */ h = COLLECT_NONDIRTY_FREQ1 - COLLECT_NONDIRTY_FREQ2; base = COLLECT_NONDIRTY_BASE; x = dist - base; y = (x * h + base / 2) / base; return COLLECT_NONDIRTY_FREQ2 + y; } static int mtdswap_choose_wl_tree(struct mtdswap_dev *d) { static unsigned int pick_cnt; unsigned int i, idx = -1, wear, max; struct rb_root *root; max = 0; for (i = 0; i <= MTDSWAP_DIRTY; i++) { root = &d->trees[i].root; if (root->rb_node == NULL) continue; wear = d->max_erase_count - MTDSWAP_ECNT_MIN(root); if (wear > max) { max = wear; idx = i; } } if (max > MAX_ERASE_DIFF && pick_cnt >= mtdswap_wlfreq(max) - 1) { pick_cnt = 0; return idx; } pick_cnt++; return -1; } static int mtdswap_choose_gc_tree(struct mtdswap_dev *d, unsigned int background) { int idx; if (TREE_NONEMPTY(d, FAILING) && (background || (TREE_EMPTY(d, CLEAN) && TREE_EMPTY(d, DIRTY)))) return MTDSWAP_FAILING; idx = mtdswap_choose_wl_tree(d); if (idx >= MTDSWAP_CLEAN) return idx; return __mtdswap_choose_gc_tree(d); } static struct swap_eb *mtdswap_pick_gc_eblk(struct mtdswap_dev *d, unsigned int background) { struct rb_root *rp = NULL; struct swap_eb *eb = NULL; int idx; if (background && TREE_COUNT(d, CLEAN) > CLEAN_BLOCK_THRESHOLD && TREE_EMPTY(d, DIRTY) && TREE_EMPTY(d, FAILING)) return NULL; idx = mtdswap_choose_gc_tree(d, background); if (idx < 0) return NULL; rp = &d->trees[idx].root; eb = rb_entry(rb_first(rp), struct swap_eb, rb); rb_erase(&eb->rb, rp); eb->root = NULL; d->trees[idx].count--; return eb; } static unsigned int mtdswap_test_patt(unsigned int i) { return i % 2 ? 0x55555555 : 0xAAAAAAAA; } static unsigned int mtdswap_eblk_passes(struct mtdswap_dev *d, struct swap_eb *eb) { struct mtd_info *mtd = d->mtd; unsigned int test, i, j, patt, mtd_pages; loff_t base, pos; unsigned int *p1 = (unsigned int *)d->page_buf; unsigned char *p2 = (unsigned char *)d->oob_buf; struct mtd_oob_ops ops; int ret; ops.mode = MTD_OOB_AUTO; ops.len = mtd->writesize; ops.ooblen = mtd->ecclayout->oobavail; ops.ooboffs = 0; ops.datbuf = d->page_buf; ops.oobbuf = d->oob_buf; base = mtdswap_eb_offset(d, eb); mtd_pages = d->pages_per_eblk * PAGE_SIZE / mtd->writesize; for (test = 0; test < 2; test++) { pos = base; for (i = 0; i < mtd_pages; i++) { patt = mtdswap_test_patt(test + i); memset(d->page_buf, patt, mtd->writesize); memset(d->oob_buf, patt, mtd->ecclayout->oobavail); ret = mtd->write_oob(mtd, pos, &ops); if (ret) goto error; pos += mtd->writesize; } pos = base; for (i = 0; i < mtd_pages; i++) { ret = mtd->read_oob(mtd, pos, &ops); if (ret) goto error; patt = mtdswap_test_patt(test + i); for (j = 0; j < mtd->writesize/sizeof(int); j++) if (p1[j] != patt) goto error; for (j = 0; j < mtd->ecclayout->oobavail; j++) if (p2[j] != (unsigned char)patt) goto error; pos += mtd->writesize; } ret = mtdswap_erase_block(d, eb); if (ret) goto error; } eb->flags &= ~EBLOCK_READERR; return 1; error: mtdswap_handle_badblock(d, eb); return 0; } static int mtdswap_gc(struct mtdswap_dev *d, unsigned int background) { struct swap_eb *eb; int ret; if (d->spare_eblks < MIN_SPARE_EBLOCKS) return 1; eb = mtdswap_pick_gc_eblk(d, background); if (!eb) return 1; ret = mtdswap_gc_eblock(d, eb); if (ret == -ENOSPC) return 1; if (eb->flags & EBLOCK_FAILED) { mtdswap_handle_badblock(d, eb); return 0; } eb->flags &= ~EBLOCK_BITFLIP; ret = mtdswap_erase_block(d, eb); if ((eb->flags & EBLOCK_READERR) && (ret || !mtdswap_eblk_passes(d, eb))) return 0; if (ret == 0) ret = mtdswap_write_marker(d, eb, MTDSWAP_TYPE_CLEAN); if (ret == 0) mtdswap_rb_add(d, eb, MTDSWAP_CLEAN); else if (ret != -EIO && ret != -EBADMSG) mtdswap_rb_add(d, eb, MTDSWAP_DIRTY); return 0; } static void mtdswap_background(struct mtd_blktrans_dev *dev) { struct mtdswap_dev *d = MTDSWAP_MBD_TO_MTDSWAP(dev); int ret; while (1) { ret = mtdswap_gc(d, 1); if (ret || mtd_blktrans_cease_background(dev)) return; } } static void mtdswap_cleanup(struct mtdswap_dev *d) { vfree(d->eb_data); vfree(d->revmap); vfree(d->page_data); kfree(d->oob_buf); kfree(d->page_buf); } static int mtdswap_flush(struct mtd_blktrans_dev *dev) { struct mtdswap_dev *d = MTDSWAP_MBD_TO_MTDSWAP(dev); if (d->mtd->sync) d->mtd->sync(d->mtd); return 0; } static unsigned int mtdswap_badblocks(struct mtd_info *mtd, uint64_t size) { loff_t offset; unsigned int badcnt; badcnt = 0; if (mtd->block_isbad) for (offset = 0; offset < size; offset += mtd->erasesize) if (mtd->block_isbad(mtd, offset)) badcnt++; return badcnt; } static int mtdswap_writesect(struct mtd_blktrans_dev *dev, unsigned long page, char *buf) { struct mtdswap_dev *d = MTDSWAP_MBD_TO_MTDSWAP(dev); unsigned int newblock, mapped; struct swap_eb *eb; int ret; d->sect_write_count++; if (d->spare_eblks < MIN_SPARE_EBLOCKS) return -ENOSPC; if (header) { /* Ignore writes to the header page */ if (unlikely(page == 0)) return 0; page--; } mapped = d->page_data[page]; if (mapped <= BLOCK_MAX) { eb = d->eb_data + (mapped / d->pages_per_eblk); eb->active_count--; mtdswap_store_eb(d, eb); d->page_data[page] = BLOCK_UNDEF; d->revmap[mapped] = PAGE_UNDEF; } ret = mtdswap_write_block(d, buf, page, &newblock, 0); d->mtd_write_count++; if (ret < 0) return ret; eb = d->eb_data + (newblock / d->pages_per_eblk); d->page_data[page] = newblock; return 0; } /* Provide a dummy swap header for the kernel */ static int mtdswap_auto_header(struct mtdswap_dev *d, char *buf) { union swap_header *hd = (union swap_header *)(buf); memset(buf, 0, PAGE_SIZE - 10); hd->info.version = 1; hd->info.last_page = d->mbd_dev->size - 1; hd->info.nr_badpages = 0; memcpy(buf + PAGE_SIZE - 10, "SWAPSPACE2", 10); return 0; } static int mtdswap_readsect(struct mtd_blktrans_dev *dev, unsigned long page, char *buf) { struct mtdswap_dev *d = MTDSWAP_MBD_TO_MTDSWAP(dev); struct mtd_info *mtd = d->mtd; unsigned int realblock, retries; loff_t readpos; struct swap_eb *eb; size_t retlen; int ret; d->sect_read_count++; if (header) { if (unlikely(page == 0)) return mtdswap_auto_header(d, buf); page--; } realblock = d->page_data[page]; if (realblock > BLOCK_MAX) { memset(buf, 0x0, PAGE_SIZE); if (realblock == BLOCK_UNDEF) return 0; else return -EIO; } eb = d->eb_data + (realblock / d->pages_per_eblk); BUG_ON(d->revmap[realblock] == PAGE_UNDEF); readpos = (loff_t)realblock << PAGE_SHIFT; retries = 0; retry: ret = mtd->read(mtd, readpos, PAGE_SIZE, &retlen, buf); d->mtd_read_count++; if (ret == -EUCLEAN) { eb->flags |= EBLOCK_BITFLIP; mtdswap_rb_add(d, eb, MTDSWAP_BITFLIP); ret = 0; } if (ret < 0) { dev_err(d->dev, "Read error %d\n", ret); eb->flags |= EBLOCK_READERR; mtdswap_rb_add(d, eb, MTDSWAP_FAILING); retries++; if (retries < MTDSWAP_IO_RETRIES) goto retry; return ret; } if (retlen != PAGE_SIZE) { dev_err(d->dev, "Short read %zd\n", retlen); return -EIO; } return 0; } static int mtdswap_discard(struct mtd_blktrans_dev *dev, unsigned long first, unsigned nr_pages) { struct mtdswap_dev *d = MTDSWAP_MBD_TO_MTDSWAP(dev); unsigned long page; struct swap_eb *eb; unsigned int mapped; d->discard_count++; for (page = first; page < first + nr_pages; page++) { mapped = d->page_data[page]; if (mapped <= BLOCK_MAX) { eb = d->eb_data + (mapped / d->pages_per_eblk); eb->active_count--; mtdswap_store_eb(d, eb); d->page_data[page] = BLOCK_UNDEF; d->revmap[mapped] = PAGE_UNDEF; d->discard_page_count++; } else if (mapped == BLOCK_ERROR) { d->page_data[page] = BLOCK_UNDEF; d->discard_page_count++; } } return 0; } static int mtdswap_show(struct seq_file *s, void *data) { struct mtdswap_dev *d = (struct mtdswap_dev *) s->private; unsigned long sum; unsigned int count[MTDSWAP_TREE_CNT]; unsigned int min[MTDSWAP_TREE_CNT]; unsigned int max[MTDSWAP_TREE_CNT]; unsigned int i, cw = 0, cwp = 0, cwecount = 0, bb_cnt, mapped, pages; uint64_t use_size; char *name[] = {"clean", "used", "low", "high", "dirty", "bitflip", "failing"}; mutex_lock(&d->mbd_dev->lock); for (i = 0; i < MTDSWAP_TREE_CNT; i++) { struct rb_root *root = &d->trees[i].root; if (root->rb_node) { count[i] = d->trees[i].count; min[i] = rb_entry(rb_first(root), struct swap_eb, rb)->erase_count; max[i] = rb_entry(rb_last(root), struct swap_eb, rb)->erase_count; } else count[i] = 0; } if (d->curr_write) { cw = 1; cwp = d->curr_write_pos; cwecount = d->curr_write->erase_count; } sum = 0; for (i = 0; i < d->eblks; i++) sum += d->eb_data[i].erase_count; use_size = (uint64_t)d->eblks * d->mtd->erasesize; bb_cnt = mtdswap_badblocks(d->mtd, use_size); mapped = 0; pages = d->mbd_dev->size; for (i = 0; i < pages; i++) if (d->page_data[i] != BLOCK_UNDEF) mapped++; mutex_unlock(&d->mbd_dev->lock); for (i = 0; i < MTDSWAP_TREE_CNT; i++) { if (!count[i]) continue; if (min[i] != max[i]) seq_printf(s, "%s:\t%5d erase blocks, erased min %d, " "max %d times\n", name[i], count[i], min[i], max[i]); else seq_printf(s, "%s:\t%5d erase blocks, all erased %d " "times\n", name[i], count[i], min[i]); } if (bb_cnt) seq_printf(s, "bad:\t%5u erase blocks\n", bb_cnt); if (cw) seq_printf(s, "current erase block: %u pages used, %u free, " "erased %u times\n", cwp, d->pages_per_eblk - cwp, cwecount); seq_printf(s, "total erasures: %lu\n", sum); seq_printf(s, "\n"); seq_printf(s, "mtdswap_readsect count: %llu\n", d->sect_read_count); seq_printf(s, "mtdswap_writesect count: %llu\n", d->sect_write_count); seq_printf(s, "mtdswap_discard count: %llu\n", d->discard_count); seq_printf(s, "mtd read count: %llu\n", d->mtd_read_count); seq_printf(s, "mtd write count: %llu\n", d->mtd_write_count); seq_printf(s, "discarded pages count: %llu\n", d->discard_page_count); seq_printf(s, "\n"); seq_printf(s, "total pages: %u\n", pages); seq_printf(s, "pages mapped: %u\n", mapped); return 0; } static int mtdswap_open(struct inode *inode, struct file *file) { return single_open(file, mtdswap_show, inode->i_private); } static const struct file_operations mtdswap_fops = { .open = mtdswap_open, .read = seq_read, .llseek = seq_lseek, .release = single_release, }; static int mtdswap_add_debugfs(struct mtdswap_dev *d) { struct gendisk *gd = d->mbd_dev->disk; struct device *dev = disk_to_dev(gd); struct dentry *root; struct dentry *dent; root = debugfs_create_dir(gd->disk_name, NULL); if (IS_ERR(root)) return 0; if (!root) { dev_err(dev, "failed to initialize debugfs\n"); return -1; } d->debugfs_root = root; dent = debugfs_create_file("stats", S_IRUSR, root, d, &mtdswap_fops); if (!dent) { dev_err(d->dev, "debugfs_create_file failed\n"); debugfs_remove_recursive(root); d->debugfs_root = NULL; return -1; } return 0; } static int mtdswap_init(struct mtdswap_dev *d, unsigned int eblocks, unsigned int spare_cnt) { struct mtd_info *mtd = d->mbd_dev->mtd; unsigned int i, eblk_bytes, pages, blocks; int ret = -ENOMEM; d->mtd = mtd; d->eblks = eblocks; d->spare_eblks = spare_cnt; d->pages_per_eblk = mtd->erasesize >> PAGE_SHIFT; pages = d->mbd_dev->size; blocks = eblocks * d->pages_per_eblk; for (i = 0; i < MTDSWAP_TREE_CNT; i++) d->trees[i].root = RB_ROOT; d->page_data = vmalloc(sizeof(int)*pages); if (!d->page_data) goto page_data_fail; d->revmap = vmalloc(sizeof(int)*blocks); if (!d->revmap) goto revmap_fail; eblk_bytes = sizeof(struct swap_eb)*d->eblks; d->eb_data = vmalloc(eblk_bytes); if (!d->eb_data) goto eb_data_fail; memset(d->eb_data, 0, eblk_bytes); for (i = 0; i < pages; i++) d->page_data[i] = BLOCK_UNDEF; for (i = 0; i < blocks; i++) d->revmap[i] = PAGE_UNDEF; d->page_buf = kmalloc(PAGE_SIZE, GFP_KERNEL); if (!d->page_buf) goto page_buf_fail; d->oob_buf = kmalloc(2 * mtd->ecclayout->oobavail, GFP_KERNEL); if (!d->oob_buf) goto oob_buf_fail; mtdswap_scan_eblks(d); return 0; oob_buf_fail: kfree(d->page_buf); page_buf_fail: vfree(d->eb_data); eb_data_fail: vfree(d->revmap); revmap_fail: vfree(d->page_data); page_data_fail: printk(KERN_ERR "%s: init failed (%d)\n", MTDSWAP_PREFIX, ret); return ret; } static void mtdswap_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd) { struct mtdswap_dev *d; struct mtd_blktrans_dev *mbd_dev; char *parts; char *this_opt; unsigned long part; unsigned int eblocks, eavailable, bad_blocks, spare_cnt; uint64_t swap_size, use_size, size_limit; struct nand_ecclayout *oinfo; int ret; parts = &partitions[0]; if (!*parts) return; while ((this_opt = strsep(&parts, ",")) != NULL) { if (strict_strtoul(this_opt, 0, &part) < 0) return; if (mtd->index == part) break; } if (mtd->index != part) return; if (mtd->erasesize < PAGE_SIZE || mtd->erasesize % PAGE_SIZE) { printk(KERN_ERR "%s: Erase size %u not multiple of PAGE_SIZE " "%lu\n", MTDSWAP_PREFIX, mtd->erasesize, PAGE_SIZE); return; } if (PAGE_SIZE % mtd->writesize || mtd->writesize > PAGE_SIZE) { printk(KERN_ERR "%s: PAGE_SIZE %lu not multiple of write size" " %u\n", MTDSWAP_PREFIX, PAGE_SIZE, mtd->writesize); return; } oinfo = mtd->ecclayout; if (!oinfo) { printk(KERN_ERR "%s: mtd%d does not have OOB\n", MTDSWAP_PREFIX, mtd->index); return; } if (!mtd->oobsize || oinfo->oobavail < MTDSWAP_OOBSIZE) { printk(KERN_ERR "%s: Not enough free bytes in OOB, " "%d available, %zu needed.\n", MTDSWAP_PREFIX, oinfo->oobavail, MTDSWAP_OOBSIZE); return; } if (spare_eblocks > 100) spare_eblocks = 100; use_size = mtd->size; size_limit = (uint64_t) BLOCK_MAX * PAGE_SIZE; if (mtd->size > size_limit) { printk(KERN_WARNING "%s: Device too large. Limiting size to " "%llu bytes\n", MTDSWAP_PREFIX, size_limit); use_size = size_limit; } eblocks = mtd_div_by_eb(use_size, mtd); use_size = eblocks * mtd->erasesize; bad_blocks = mtdswap_badblocks(mtd, use_size); eavailable = eblocks - bad_blocks; if (eavailable < MIN_ERASE_BLOCKS) { printk(KERN_ERR "%s: Not enough erase blocks. %u available, " "%d needed\n", MTDSWAP_PREFIX, eavailable, MIN_ERASE_BLOCKS); return; } spare_cnt = div_u64((uint64_t)eavailable * spare_eblocks, 100); if (spare_cnt < MIN_SPARE_EBLOCKS) spare_cnt = MIN_SPARE_EBLOCKS; if (spare_cnt > eavailable - 1) spare_cnt = eavailable - 1; swap_size = (uint64_t)(eavailable - spare_cnt) * mtd->erasesize + (header ? PAGE_SIZE : 0); printk(KERN_INFO "%s: Enabling MTD swap on device %lu, size %llu KB, " "%u spare, %u bad blocks\n", MTDSWAP_PREFIX, part, swap_size / 1024, spare_cnt, bad_blocks); d = kzalloc(sizeof(struct mtdswap_dev), GFP_KERNEL); if (!d) return; mbd_dev = kzalloc(sizeof(struct mtd_blktrans_dev), GFP_KERNEL); if (!mbd_dev) { kfree(d); return; } d->mbd_dev = mbd_dev; mbd_dev->priv = d; mbd_dev->mtd = mtd; mbd_dev->devnum = mtd->index; mbd_dev->size = swap_size >> PAGE_SHIFT; mbd_dev->tr = tr; if (!(mtd->flags & MTD_WRITEABLE)) mbd_dev->readonly = 1; if (mtdswap_init(d, eblocks, spare_cnt) < 0) goto init_failed; if (add_mtd_blktrans_dev(mbd_dev) < 0) goto cleanup; d->dev = disk_to_dev(mbd_dev->disk); ret = mtdswap_add_debugfs(d); if (ret < 0) goto debugfs_failed; return; debugfs_failed: del_mtd_blktrans_dev(mbd_dev); cleanup: mtdswap_cleanup(d); init_failed: kfree(mbd_dev); kfree(d); } static void mtdswap_remove_dev(struct mtd_blktrans_dev *dev) { struct mtdswap_dev *d = MTDSWAP_MBD_TO_MTDSWAP(dev); debugfs_remove_recursive(d->debugfs_root); del_mtd_blktrans_dev(dev); mtdswap_cleanup(d); kfree(d); } static struct mtd_blktrans_ops mtdswap_ops = { .name = "mtdswap", .major = 0, .part_bits = 0, .blksize = PAGE_SIZE, .flush = mtdswap_flush, .readsect = mtdswap_readsect, .writesect = mtdswap_writesect, .discard = mtdswap_discard, .background = mtdswap_background, .add_mtd = mtdswap_add_mtd, .remove_dev = mtdswap_remove_dev, .owner = THIS_MODULE, }; static int __init mtdswap_modinit(void) { return register_mtd_blktrans(&mtdswap_ops); } static void __exit mtdswap_modexit(void) { deregister_mtd_blktrans(&mtdswap_ops); } module_init(mtdswap_modinit); module_exit(mtdswap_modexit); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Jarkko Lavinen <jarkko.lavinen@nokia.com>"); MODULE_DESCRIPTION("Block device access to an MTD suitable for using as " "swap space");