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authorJarkko Lavinen <jarkko.lavinen@nokia.com>2011-02-14 16:16:11 +0200
committerDavid Woodhouse <David.Woodhouse@intel.com>2011-03-11 14:22:46 +0000
commita321590246202f2598aca2f4ef63b992e8fc97ef (patch)
treecbb838704f7575bf5634c95fd1d91bef24e9d296 /drivers/mtd/mtdswap.c
parent115ee88c15b55859a8b59c5dccb3882bbd47e542 (diff)
downloadlinux-a321590246202f2598aca2f4ef63b992e8fc97ef.tar.gz
mtd: Add mtdswap block driver
Add a driver for allowing an mtd device to be used as a block device for swapping. The block device is volatile, and the mapping of swapped pages is not stored on flash. Signed-off-by: Jarkko Lavinen <jarkko.lavinen@nokia.com> Tested-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Diffstat (limited to 'drivers/mtd/mtdswap.c')
-rw-r--r--drivers/mtd/mtdswap.c1593
1 files changed, 1593 insertions, 0 deletions
diff --git a/drivers/mtd/mtdswap.c b/drivers/mtd/mtdswap.c
new file mode 100644
index 00000000000..57e6cc30bc4
--- /dev/null
+++ b/drivers/mtd/mtdswap.c
@@ -0,0 +1,1593 @@
+/*
+ * 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
+
+#ifdef CONFIG_MTD_SWAP_STRICT
+#define MTDSWAP_STRICT 1
+#else
+#define MTDSWAP_STRICT 0
+#endif
+
+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 "
+ "%d) 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 %d\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 && !MTDSWAP_STRICT) {
+ 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 (%d written)",
+ ret, retlen);
+ goto err;
+ }
+
+ if (retlen != PAGE_SIZE) {
+ dev_err(d->dev, "Short write to MTD device: %d 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: %d (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, 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 %d\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: %lu\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 (!mtd->oobsize || !oinfo || oinfo->oobavail < MTDSWAP_OOBSIZE) {
+ printk(KERN_ERR "%s: Not enough free bytes in OOB, "
+ "%d available, %u 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");