[JFFS2] Avoid alloc/dealloc for zero sized nodes

[linux-2.6] / fs / jffs2 / wbuf.c

/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright (C) 2001-2003 Red Hat, Inc.
 * Copyright (C) 2004 Thomas Gleixner <tglx@linutronix.de>
 *
 * Created by David Woodhouse <dwmw2@infradead.org>
 * Modified debugged and enhanced by Thomas Gleixner <tglx@linutronix.de>
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 * $Id: wbuf.c,v 1.92 2005/04/05 12:51:54 dedekind Exp $
 *
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mtd/mtd.h>
#include <linux/crc32.h>
#include <linux/mtd/nand.h>
#include "nodelist.h"

/* For testing write failures */
#undef BREAKME
#undef BREAKMEHEADER

#ifdef BREAKME
static unsigned char *brokenbuf;
#endif

/* max. erase failures before we mark a block bad */
#define MAX_ERASE_FAILURES      2

/* two seconds timeout for timed wbuf-flushing */
#define WBUF_FLUSH_TIMEOUT      2 * HZ

struct jffs2_inodirty {
        uint32_t ino;
        struct jffs2_inodirty *next;
};

static struct jffs2_inodirty inodirty_nomem;

static int jffs2_wbuf_pending_for_ino(struct jffs2_sb_info *c, uint32_t ino)
{
        struct jffs2_inodirty *this = c->wbuf_inodes;

        /* If a malloc failed, consider _everything_ dirty */
        if (this == &inodirty_nomem)
                return 1;

        /* If ino == 0, _any_ non-GC writes mean 'yes' */
        if (this && !ino)
                return 1;

        /* Look to see if the inode in question is pending in the wbuf */
        while (this) {
                if (this->ino == ino)
                        return 1;
                this = this->next;
        }
        return 0;
}

static void jffs2_clear_wbuf_ino_list(struct jffs2_sb_info *c)
{
        struct jffs2_inodirty *this;

        this = c->wbuf_inodes;

        if (this != &inodirty_nomem) {
                while (this) {
                        struct jffs2_inodirty *next = this->next;
                        kfree(this);
                        this = next;
                }
        }
        c->wbuf_inodes = NULL;
}

static void jffs2_wbuf_dirties_inode(struct jffs2_sb_info *c, uint32_t ino)
{
        struct jffs2_inodirty *new;

        /* Mark the superblock dirty so that kupdated will flush... */
        jffs2_erase_pending_trigger(c);

        if (jffs2_wbuf_pending_for_ino(c, ino))
                return;

        new = kmalloc(sizeof(*new), GFP_KERNEL);
        if (!new) {
                D1(printk(KERN_DEBUG "No memory to allocate inodirty. Fallback to all considered dirty\n"));
                jffs2_clear_wbuf_ino_list(c);
                c->wbuf_inodes = &inodirty_nomem;
                return;
        }
        new->ino = ino;
        new->next = c->wbuf_inodes;
        c->wbuf_inodes = new;
        return;
}

static inline void jffs2_refile_wbuf_blocks(struct jffs2_sb_info *c)
{
        struct list_head *this, *next;
        static int n;

        if (list_empty(&c->erasable_pending_wbuf_list))
                return;

        list_for_each_safe(this, next, &c->erasable_pending_wbuf_list) {
                struct jffs2_eraseblock *jeb = list_entry(this, struct jffs2_eraseblock, list);

                D1(printk(KERN_DEBUG "Removing eraseblock at 0x%08x from erasable_pending_wbuf_list...\n", jeb->offset));
                list_del(this);
                if ((jiffies + (n++)) & 127) {
                        /* Most of the time, we just erase it immediately. Otherwise we
                           spend ages scanning it on mount, etc. */
                        D1(printk(KERN_DEBUG "...and adding to erase_pending_list\n"));
                        list_add_tail(&jeb->list, &c->erase_pending_list);
                        c->nr_erasing_blocks++;
                        jffs2_erase_pending_trigger(c);
                } else {
                        /* Sometimes, however, we leave it elsewhere so it doesn't get
                           immediately reused, and we spread the load a bit. */
                        D1(printk(KERN_DEBUG "...and adding to erasable_list\n"));
                        list_add_tail(&jeb->list, &c->erasable_list);
                }
        }
}

#define REFILE_NOTEMPTY 0
#define REFILE_ANYWAY   1

static void jffs2_block_refile(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb, int allow_empty)
{
        D1(printk("About to refile bad block at %08x\n", jeb->offset));

        D2(jffs2_dump_block_lists(c));
        /* File the existing block on the bad_used_list.... */
        if (c->nextblock == jeb)
                c->nextblock = NULL;
        else /* Not sure this should ever happen... need more coffee */
                list_del(&jeb->list);
        if (jeb->first_node) {
                D1(printk("Refiling block at %08x to bad_used_list\n", jeb->offset));
                list_add(&jeb->list, &c->bad_used_list);
        } else {
                BUG_ON(allow_empty == REFILE_NOTEMPTY);
                /* It has to have had some nodes or we couldn't be here */
                D1(printk("Refiling block at %08x to erase_pending_list\n", jeb->offset));
                list_add(&jeb->list, &c->erase_pending_list);
                c->nr_erasing_blocks++;
                jffs2_erase_pending_trigger(c);
        }
        D2(jffs2_dump_block_lists(c));

        /* Adjust its size counts accordingly */
        c->wasted_size += jeb->free_size;
        c->free_size -= jeb->free_size;
        jeb->wasted_size += jeb->free_size;
        jeb->free_size = 0;

        ACCT_SANITY_CHECK(c,jeb);
        D1(ACCT_PARANOIA_CHECK(jeb));
}

/* Recover from failure to write wbuf. Recover the nodes up to the
 * wbuf, not the one which we were starting to try to write. */

static void jffs2_wbuf_recover(struct jffs2_sb_info *c)
{
        struct jffs2_eraseblock *jeb, *new_jeb;
        struct jffs2_raw_node_ref **first_raw, **raw;
        size_t retlen;
        int ret;
        unsigned char *buf;
        uint32_t start, end, ofs, len;

        spin_lock(&c->erase_completion_lock);

        jeb = &c->blocks[c->wbuf_ofs / c->sector_size];

        jffs2_block_refile(c, jeb, REFILE_NOTEMPTY);

        /* Find the first node to be recovered, by skipping over every
           node which ends before the wbuf starts, or which is obsolete. */
        first_raw = &jeb->first_node;
        while (*first_raw && 
               (ref_obsolete(*first_raw) ||
                (ref_offset(*first_raw)+ref_totlen(c, jeb, *first_raw)) < c->wbuf_ofs)) {
                D1(printk(KERN_DEBUG "Skipping node at 0x%08x(%d)-0x%08x which is either before 0x%08x or obsolete\n",
                          ref_offset(*first_raw), ref_flags(*first_raw),
                          (ref_offset(*first_raw) + ref_totlen(c, jeb, *first_raw)),
                          c->wbuf_ofs));
                first_raw = &(*first_raw)->next_phys;
        }

        if (!*first_raw) {
                /* All nodes were obsolete. Nothing to recover. */
                D1(printk(KERN_DEBUG "No non-obsolete nodes to be recovered. Just filing block bad\n"));
                spin_unlock(&c->erase_completion_lock);
                return;
        }

        start = ref_offset(*first_raw);
        end = ref_offset(*first_raw) + ref_totlen(c, jeb, *first_raw);

        /* Find the last node to be recovered */
        raw = first_raw;
        while ((*raw)) {
                if (!ref_obsolete(*raw))
                        end = ref_offset(*raw) + ref_totlen(c, jeb, *raw);

                raw = &(*raw)->next_phys;
        }
        spin_unlock(&c->erase_completion_lock);

        D1(printk(KERN_DEBUG "wbuf recover %08x-%08x\n", start, end));

        buf = NULL;
        if (start < c->wbuf_ofs) {
                /* First affected node was already partially written.
                 * Attempt to reread the old data into our buffer. */

                buf = kmalloc(end - start, GFP_KERNEL);
                if (!buf) {
                        printk(KERN_CRIT "Malloc failure in wbuf recovery. Data loss ensues.\n");

                        goto read_failed;
                }

                /* Do the read... */
                if (jffs2_cleanmarker_oob(c))
                        ret = c->mtd->read_ecc(c->mtd, start, c->wbuf_ofs - start, &retlen, buf, NULL, c->oobinfo);
                else
                        ret = c->mtd->read(c->mtd, start, c->wbuf_ofs - start, &retlen, buf);
                
                if (ret == -EBADMSG && retlen == c->wbuf_ofs - start) {
                        /* ECC recovered */
                        ret = 0;
                }
                if (ret || retlen != c->wbuf_ofs - start) {
                        printk(KERN_CRIT "Old data are already lost in wbuf recovery. Data loss ensues.\n");

                        kfree(buf);
                        buf = NULL;
                read_failed:
                        first_raw = &(*first_raw)->next_phys;
                        /* If this was the only node to be recovered, give up */
                        if (!(*first_raw))
                                return;

                        /* It wasn't. Go on and try to recover nodes complete in the wbuf */
                        start = ref_offset(*first_raw);
                } else {
                        /* Read succeeded. Copy the remaining data from the wbuf */
                        memcpy(buf + (c->wbuf_ofs - start), c->wbuf, end - c->wbuf_ofs);
                }
        }
        /* OK... we're to rewrite (end-start) bytes of data from first_raw onwards.
           Either 'buf' contains the data, or we find it in the wbuf */


        /* ... and get an allocation of space from a shiny new block instead */
        ret = jffs2_reserve_space_gc(c, end-start, &ofs, &len);
        if (ret) {
                printk(KERN_WARNING "Failed to allocate space for wbuf recovery. Data loss ensues.\n");
                kfree(buf);
                return;
        }
        if (end-start >= c->wbuf_pagesize) {
                /* Need to do another write immediately, but it's possible
                   that this is just because the wbuf itself is completely
                   full, and there's nothing earlier read back from the 
                   flash. Hence 'buf' isn't necessarily what we're writing 
                   from. */
                unsigned char *rewrite_buf = buf?:c->wbuf;
                uint32_t towrite = (end-start) - ((end-start)%c->wbuf_pagesize);

                D1(printk(KERN_DEBUG "Write 0x%x bytes at 0x%08x in wbuf recover\n",
                          towrite, ofs));
          
#ifdef BREAKMEHEADER
                static int breakme;
                if (breakme++ == 20) {
                        printk(KERN_NOTICE "Faking write error at 0x%08x\n", ofs);
                        breakme = 0;
                        c->mtd->write_ecc(c->mtd, ofs, towrite, &retlen,
                                          brokenbuf, NULL, c->oobinfo);
                        ret = -EIO;
                } else
#endif
                if (jffs2_cleanmarker_oob(c))
                        ret = c->mtd->write_ecc(c->mtd, ofs, towrite, &retlen,
                                                rewrite_buf, NULL, c->oobinfo);
                else
                        ret = c->mtd->write(c->mtd, ofs, towrite, &retlen, rewrite_buf);

                if (ret || retlen != towrite) {
                        /* Argh. We tried. Really we did. */
                        printk(KERN_CRIT "Recovery of wbuf failed due to a second write error\n");
                        kfree(buf);

                        if (retlen) {
                                struct jffs2_raw_node_ref *raw2;

                                raw2 = jffs2_alloc_raw_node_ref();
                                if (!raw2)
                                        return;

                                raw2->flash_offset = ofs | REF_OBSOLETE;
                                raw2->__totlen = ref_totlen(c, jeb, *first_raw);
                                raw2->next_phys = NULL;
                                raw2->next_in_ino = NULL;

                                jffs2_add_physical_node_ref(c, raw2);
                        }
                        return;
                }
                printk(KERN_NOTICE "Recovery of wbuf succeeded to %08x\n", ofs);

                c->wbuf_len = (end - start) - towrite;
                c->wbuf_ofs = ofs + towrite;
                memmove(c->wbuf, rewrite_buf + towrite, c->wbuf_len);
                /* Don't muck about with c->wbuf_inodes. False positives are harmless. */
                if (buf)
                        kfree(buf);
        } else {
                /* OK, now we're left with the dregs in whichever buffer we're using */
                if (buf) {
                        memcpy(c->wbuf, buf, end-start);
                        kfree(buf);
                } else {
                        memmove(c->wbuf, c->wbuf + (start - c->wbuf_ofs), end - start);
                }
                c->wbuf_ofs = ofs;
                c->wbuf_len = end - start;
        }

        /* Now sort out the jffs2_raw_node_refs, moving them from the old to the next block */
        new_jeb = &c->blocks[ofs / c->sector_size];

        spin_lock(&c->erase_completion_lock);
        if (new_jeb->first_node) {
                /* Odd, but possible with ST flash later maybe */
                new_jeb->last_node->next_phys = *first_raw;
        } else {
                new_jeb->first_node = *first_raw;
        }

        raw = first_raw;
        while (*raw) {
                uint32_t rawlen = ref_totlen(c, jeb, *raw);

                D1(printk(KERN_DEBUG "Refiling block of %08x at %08x(%d) to %08x\n",
                          rawlen, ref_offset(*raw), ref_flags(*raw), ofs));

                if (ref_obsolete(*raw)) {
                        /* Shouldn't really happen much */
                        new_jeb->dirty_size += rawlen;
                        new_jeb->free_size -= rawlen;
                        c->dirty_size += rawlen;
                } else {
                        new_jeb->used_size += rawlen;
                        new_jeb->free_size -= rawlen;
                        jeb->dirty_size += rawlen;
                        jeb->used_size  -= rawlen;
                        c->dirty_size += rawlen;
                }
                c->free_size -= rawlen;
                (*raw)->flash_offset = ofs | ref_flags(*raw);
                ofs += rawlen;
                new_jeb->last_node = *raw;

                raw = &(*raw)->next_phys;
        }

        /* Fix up the original jeb now it's on the bad_list */
        *first_raw = NULL;
        if (first_raw == &jeb->first_node) {
                jeb->last_node = NULL;
                D1(printk(KERN_DEBUG "Failing block at %08x is now empty. Moving to erase_pending_list\n", jeb->offset));
                list_del(&jeb->list);
                list_add(&jeb->list, &c->erase_pending_list);
                c->nr_erasing_blocks++;
                jffs2_erase_pending_trigger(c);
        }
        else
                jeb->last_node = container_of(first_raw, struct jffs2_raw_node_ref, next_phys);

        ACCT_SANITY_CHECK(c,jeb);
        D1(ACCT_PARANOIA_CHECK(jeb));

        ACCT_SANITY_CHECK(c,new_jeb);
        D1(ACCT_PARANOIA_CHECK(new_jeb));

        spin_unlock(&c->erase_completion_lock);

        D1(printk(KERN_DEBUG "wbuf recovery completed OK\n"));
}

/* Meaning of pad argument:
   0: Do not pad. Probably pointless - we only ever use this when we can't pad anyway.
   1: Pad, do not adjust nextblock free_size
   2: Pad, adjust nextblock free_size
*/
#define NOPAD           0
#define PAD_NOACCOUNT   1
#define PAD_ACCOUNTING  2

static int __jffs2_flush_wbuf(struct jffs2_sb_info *c, int pad)
{
        int ret;
        size_t retlen;

        /* Nothing to do if not write-buffering the flash. In particular, we shouldn't
           del_timer() the timer we never initialised. */
        if (!jffs2_is_writebuffered(c))
                return 0;

        if (!down_trylock(&c->alloc_sem)) {
                up(&c->alloc_sem);
                printk(KERN_CRIT "jffs2_flush_wbuf() called with alloc_sem not locked!\n");
                BUG();
        }

        if (!c->wbuf_len)       /* already checked c->wbuf above */
                return 0;

        /* claim remaining space on the page
           this happens, if we have a change to a new block,
           or if fsync forces us to flush the writebuffer.
           if we have a switch to next page, we will not have
           enough remaining space for this. 
        */
        if (pad && !jffs2_dataflash(c)) {
                c->wbuf_len = PAD(c->wbuf_len);

                /* Pad with JFFS2_DIRTY_BITMASK initially.  this helps out ECC'd NOR
                   with 8 byte page size */
                memset(c->wbuf + c->wbuf_len, 0, c->wbuf_pagesize - c->wbuf_len);
                
                if ( c->wbuf_len + sizeof(struct jffs2_unknown_node) < c->wbuf_pagesize) {
                        struct jffs2_unknown_node *padnode = (void *)(c->wbuf + c->wbuf_len);
                        padnode->magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
                        padnode->nodetype = cpu_to_je16(JFFS2_NODETYPE_PADDING);
                        padnode->totlen = cpu_to_je32(c->wbuf_pagesize - c->wbuf_len);
                        padnode->hdr_crc = cpu_to_je32(crc32(0, padnode, sizeof(*padnode)-4));
                }
        }
        /* else jffs2_flash_writev has actually filled in the rest of the
           buffer for us, and will deal with the node refs etc. later. */
        
#ifdef BREAKME
        static int breakme;
        if (breakme++ == 20) {
                printk(KERN_NOTICE "Faking write error at 0x%08x\n", c->wbuf_ofs);
                breakme = 0;
                c->mtd->write_ecc(c->mtd, c->wbuf_ofs, c->wbuf_pagesize,
                                        &retlen, brokenbuf, NULL, c->oobinfo);
                ret = -EIO;
        } else 
#endif
        
        if (jffs2_cleanmarker_oob(c))
                ret = c->mtd->write_ecc(c->mtd, c->wbuf_ofs, c->wbuf_pagesize, &retlen, c->wbuf, NULL, c->oobinfo);
        else
                ret = c->mtd->write(c->mtd, c->wbuf_ofs, c->wbuf_pagesize, &retlen, c->wbuf);

        if (ret || retlen != c->wbuf_pagesize) {
                if (ret)
                        printk(KERN_WARNING "jffs2_flush_wbuf(): Write failed with %d\n",ret);
                else {
                        printk(KERN_WARNING "jffs2_flush_wbuf(): Write was short: %zd instead of %d\n",
                                retlen, c->wbuf_pagesize);
                        ret = -EIO;
                }

                jffs2_wbuf_recover(c);

                return ret;
        }

        spin_lock(&c->erase_completion_lock);

        /* Adjust free size of the block if we padded. */
        if (pad && !jffs2_dataflash(c)) {
                struct jffs2_eraseblock *jeb;

                jeb = &c->blocks[c->wbuf_ofs / c->sector_size];

                D1(printk(KERN_DEBUG "jffs2_flush_wbuf() adjusting free_size of %sblock at %08x\n",
                          (jeb==c->nextblock)?"next":"", jeb->offset));

                /* wbuf_pagesize - wbuf_len is the amount of space that's to be 
                   padded. If there is less free space in the block than that,
                   something screwed up */
                if (jeb->free_size < (c->wbuf_pagesize - c->wbuf_len)) {
                        printk(KERN_CRIT "jffs2_flush_wbuf(): Accounting error. wbuf at 0x%08x has 0x%03x bytes, 0x%03x left.\n",
                               c->wbuf_ofs, c->wbuf_len, c->wbuf_pagesize-c->wbuf_len);
                        printk(KERN_CRIT "jffs2_flush_wbuf(): But free_size for block at 0x%08x is only 0x%08x\n",
                               jeb->offset, jeb->free_size);
                        BUG();
                }
                jeb->free_size -= (c->wbuf_pagesize - c->wbuf_len);
                c->free_size -= (c->wbuf_pagesize - c->wbuf_len);
                jeb->wasted_size += (c->wbuf_pagesize - c->wbuf_len);
                c->wasted_size += (c->wbuf_pagesize - c->wbuf_len);
        }

        /* Stick any now-obsoleted blocks on the erase_pending_list */
        jffs2_refile_wbuf_blocks(c);
        jffs2_clear_wbuf_ino_list(c);
        spin_unlock(&c->erase_completion_lock);

        memset(c->wbuf,0xff,c->wbuf_pagesize);
        /* adjust write buffer offset, else we get a non contiguous write bug */
        c->wbuf_ofs += c->wbuf_pagesize;
        c->wbuf_len = 0;
        return 0;
}

/* Trigger garbage collection to flush the write-buffer. 
   If ino arg is zero, do it if _any_ real (i.e. not GC) writes are
   outstanding. If ino arg non-zero, do it only if a write for the 
   given inode is outstanding. */
int jffs2_flush_wbuf_gc(struct jffs2_sb_info *c, uint32_t ino)
{
        uint32_t old_wbuf_ofs;
        uint32_t old_wbuf_len;
        int ret = 0;

        D1(printk(KERN_DEBUG "jffs2_flush_wbuf_gc() called for ino #%u...\n", ino));

        if (!c->wbuf)
                return 0;

        down(&c->alloc_sem);
        if (!jffs2_wbuf_pending_for_ino(c, ino)) {
                D1(printk(KERN_DEBUG "Ino #%d not pending in wbuf. Returning\n", ino));
                up(&c->alloc_sem);
                return 0;
        }

        old_wbuf_ofs = c->wbuf_ofs;
        old_wbuf_len = c->wbuf_len;

        if (c->unchecked_size) {
                /* GC won't make any progress for a while */
                D1(printk(KERN_DEBUG "jffs2_flush_wbuf_gc() padding. Not finished checking\n"));
                down_write(&c->wbuf_sem);
                ret = __jffs2_flush_wbuf(c, PAD_ACCOUNTING);
                /* retry flushing wbuf in case jffs2_wbuf_recover
                   left some data in the wbuf */
                if (ret)
                        ret = __jffs2_flush_wbuf(c, PAD_ACCOUNTING);
                up_write(&c->wbuf_sem);
        } else while (old_wbuf_len &&
                      old_wbuf_ofs == c->wbuf_ofs) {

                up(&c->alloc_sem);

                D1(printk(KERN_DEBUG "jffs2_flush_wbuf_gc() calls gc pass\n"));

                ret = jffs2_garbage_collect_pass(c);
                if (ret) {
                        /* GC failed. Flush it with padding instead */
                        down(&c->alloc_sem);
                        down_write(&c->wbuf_sem);
                        ret = __jffs2_flush_wbuf(c, PAD_ACCOUNTING);
                        /* retry flushing wbuf in case jffs2_wbuf_recover
                           left some data in the wbuf */
                        if (ret)
                                ret = __jffs2_flush_wbuf(c, PAD_ACCOUNTING);
                        up_write(&c->wbuf_sem);
                        break;
                }
                down(&c->alloc_sem);
        }

        D1(printk(KERN_DEBUG "jffs2_flush_wbuf_gc() ends...\n"));

        up(&c->alloc_sem);
        return ret;
}

/* Pad write-buffer to end and write it, wasting space. */
int jffs2_flush_wbuf_pad(struct jffs2_sb_info *c)
{
        int ret;

        if (!c->wbuf)
                return 0;

        down_write(&c->wbuf_sem);
        ret = __jffs2_flush_wbuf(c, PAD_NOACCOUNT);
        /* retry - maybe wbuf recover left some data in wbuf. */
        if (ret)
                ret = __jffs2_flush_wbuf(c, PAD_NOACCOUNT);
        up_write(&c->wbuf_sem);

        return ret;
}

#ifdef CONFIG_JFFS2_FS_WRITEBUFFER
#define PAGE_DIV(x) ( ((unsigned long)(x) / (unsigned long)(c->wbuf_pagesize)) * (unsigned long)(c->wbuf_pagesize) )
#define PAGE_MOD(x) ( (unsigned long)(x) % (unsigned long)(c->wbuf_pagesize) )
#else
#define PAGE_DIV(x) ( (x) & (~(c->wbuf_pagesize - 1)) )
#define PAGE_MOD(x) ( (x) & (c->wbuf_pagesize - 1) )
#endif

int jffs2_flash_writev(struct jffs2_sb_info *c, const struct kvec *invecs, unsigned long count, loff_t to, size_t *retlen, uint32_t ino)
{
        struct kvec outvecs[3];
        uint32_t totlen = 0;
        uint32_t split_ofs = 0;
        uint32_t old_totlen;
        int ret, splitvec = -1;
        int invec, outvec;
        size_t wbuf_retlen;
        unsigned char *wbuf_ptr;
        size_t donelen = 0;
        uint32_t outvec_to = to;

        /* If not NAND flash, don't bother */
        if (!jffs2_is_writebuffered(c))
                return jffs2_flash_direct_writev(c, invecs, count, to, retlen);
        
        down_write(&c->wbuf_sem);

        /* If wbuf_ofs is not initialized, set it to target address */
        if (c->wbuf_ofs == 0xFFFFFFFF) {
                c->wbuf_ofs = PAGE_DIV(to);
                c->wbuf_len = PAGE_MOD(to);                     
                memset(c->wbuf,0xff,c->wbuf_pagesize);
        }

        /* Fixup the wbuf if we are moving to a new eraseblock.  The checks below
           fail for ECC'd NOR because cleanmarker == 16, so a block starts at
           xxx0010.  */
        if (jffs2_nor_ecc(c)) {
                if (((c->wbuf_ofs % c->sector_size) == 0) && !c->wbuf_len) {
                        c->wbuf_ofs = PAGE_DIV(to);
                        c->wbuf_len = PAGE_MOD(to);
                        memset(c->wbuf,0xff,c->wbuf_pagesize);
                }
        }
        
        /* Sanity checks on target address. 
           It's permitted to write at PAD(c->wbuf_len+c->wbuf_ofs), 
           and it's permitted to write at the beginning of a new 
           erase block. Anything else, and you die.
           New block starts at xxx000c (0-b = block header)
        */
        if (SECTOR_ADDR(to) != SECTOR_ADDR(c->wbuf_ofs)) {
                /* It's a write to a new block */
                if (c->wbuf_len) {
                        D1(printk(KERN_DEBUG "jffs2_flash_writev() to 0x%lx causes flush of wbuf at 0x%08x\n", (unsigned long)to, c->wbuf_ofs));
                        ret = __jffs2_flush_wbuf(c, PAD_NOACCOUNT);
                        if (ret) {
                                /* the underlying layer has to check wbuf_len to do the cleanup */
                                D1(printk(KERN_WARNING "jffs2_flush_wbuf() called from jffs2_flash_writev() failed %d\n", ret));
                                *retlen = 0;
                                goto exit;
                        }
                }
                /* set pointer to new block */
                c->wbuf_ofs = PAGE_DIV(to);
                c->wbuf_len = PAGE_MOD(to);                     
        } 

        if (to != PAD(c->wbuf_ofs + c->wbuf_len)) {
                /* We're not writing immediately after the writebuffer. Bad. */
                printk(KERN_CRIT "jffs2_flash_writev(): Non-contiguous write to %08lx\n", (unsigned long)to);
                if (c->wbuf_len)
                        printk(KERN_CRIT "wbuf was previously %08x-%08x\n",
                                          c->wbuf_ofs, c->wbuf_ofs+c->wbuf_len);
                BUG();
        }

        /* Note outvecs[3] above. We know count is never greater than 2 */
        if (count > 2) {
                printk(KERN_CRIT "jffs2_flash_writev(): count is %ld\n", count);
                BUG();
        }

        invec = 0;
        outvec = 0;

        /* Fill writebuffer first, if already in use */ 
        if (c->wbuf_len) {
                uint32_t invec_ofs = 0;

                /* adjust alignment offset */ 
                if (c->wbuf_len != PAGE_MOD(to)) {
                        c->wbuf_len = PAGE_MOD(to);
                        /* take care of alignment to next page */
                        if (!c->wbuf_len)
                                c->wbuf_len = c->wbuf_pagesize;
                }
                
                while(c->wbuf_len < c->wbuf_pagesize) {
                        uint32_t thislen;
                        
                        if (invec == count)
                                goto alldone;

                        thislen = c->wbuf_pagesize - c->wbuf_len;

                        if (thislen >= invecs[invec].iov_len)
                                thislen = invecs[invec].iov_len;
        
                        invec_ofs = thislen;

                        memcpy(c->wbuf + c->wbuf_len, invecs[invec].iov_base, thislen);
                        c->wbuf_len += thislen;
                        donelen += thislen;
                        /* Get next invec, if actual did not fill the buffer */
                        if (c->wbuf_len < c->wbuf_pagesize) 
                                invec++;
                }                       
                
                /* write buffer is full, flush buffer */
                ret = __jffs2_flush_wbuf(c, NOPAD);
                if (ret) {
                        /* the underlying layer has to check wbuf_len to do the cleanup */
                        D1(printk(KERN_WARNING "jffs2_flush_wbuf() called from jffs2_flash_writev() failed %d\n", ret));
                        /* Retlen zero to make sure our caller doesn't mark the space dirty.
                           We've already done everything that's necessary */
                        *retlen = 0;
                        goto exit;
                }
                outvec_to += donelen;
                c->wbuf_ofs = outvec_to;

                /* All invecs done ? */
                if (invec == count)
                        goto alldone;

                /* Set up the first outvec, containing the remainder of the
                   invec we partially used */
                if (invecs[invec].iov_len > invec_ofs) {
                        outvecs[0].iov_base = invecs[invec].iov_base+invec_ofs;
                        totlen = outvecs[0].iov_len = invecs[invec].iov_len-invec_ofs;
                        if (totlen > c->wbuf_pagesize) {
                                splitvec = outvec;
                                split_ofs = outvecs[0].iov_len - PAGE_MOD(totlen);
                        }
                        outvec++;
                }
                invec++;
        }

        /* OK, now we've flushed the wbuf and the start of the bits
           we have been asked to write, now to write the rest.... */

        /* totlen holds the amount of data still to be written */
        old_totlen = totlen;
        for ( ; invec < count; invec++,outvec++ ) {
                outvecs[outvec].iov_base = invecs[invec].iov_base;
                totlen += outvecs[outvec].iov_len = invecs[invec].iov_len;
                if (PAGE_DIV(totlen) != PAGE_DIV(old_totlen)) {
                        splitvec = outvec;
                        split_ofs = outvecs[outvec].iov_len - PAGE_MOD(totlen);
                        old_totlen = totlen;
                }
        }

        /* Now the outvecs array holds all the remaining data to write */
        /* Up to splitvec,split_ofs is to be written immediately. The rest
           goes into the (now-empty) wbuf */

        if (splitvec != -1) {
                uint32_t remainder;

                remainder = outvecs[splitvec].iov_len - split_ofs;
                outvecs[splitvec].iov_len = split_ofs;

                /* We did cross a page boundary, so we write some now */
                if (jffs2_cleanmarker_oob(c))
                        ret = c->mtd->writev_ecc(c->mtd, outvecs, splitvec+1, outvec_to, &wbuf_retlen, NULL, c->oobinfo); 
                else
                        ret = jffs2_flash_direct_writev(c, outvecs, splitvec+1, outvec_to, &wbuf_retlen);
                
                if (ret < 0 || wbuf_retlen != PAGE_DIV(totlen)) {
                        /* At this point we have no problem,
                           c->wbuf is empty. However refile nextblock to avoid
                           writing again to same address.
                        */
                        struct jffs2_eraseblock *jeb;

                        spin_lock(&c->erase_completion_lock);

                        jeb = &c->blocks[outvec_to / c->sector_size];
                        jffs2_block_refile(c, jeb, REFILE_ANYWAY);

                        *retlen = 0;
                        spin_unlock(&c->erase_completion_lock);
                        goto exit;
                }
                
                donelen += wbuf_retlen;
                c->wbuf_ofs = PAGE_DIV(outvec_to) + PAGE_DIV(totlen);

                if (remainder) {
                        outvecs[splitvec].iov_base += split_ofs;
                        outvecs[splitvec].iov_len = remainder;
                } else {
                        splitvec++;
                }

        } else {
                splitvec = 0;
        }

        /* Now splitvec points to the start of the bits we have to copy
           into the wbuf */
        wbuf_ptr = c->wbuf;

        for ( ; splitvec < outvec; splitvec++) {
                /* Don't copy the wbuf into itself */
                if (outvecs[splitvec].iov_base == c->wbuf)
                        continue;
                memcpy(wbuf_ptr, outvecs[splitvec].iov_base, outvecs[splitvec].iov_len);
                wbuf_ptr += outvecs[splitvec].iov_len;
                donelen += outvecs[splitvec].iov_len;
        }
        c->wbuf_len = wbuf_ptr - c->wbuf;

        /* If there's a remainder in the wbuf and it's a non-GC write,
           remember that the wbuf affects this ino */
alldone:
        *retlen = donelen;

        if (c->wbuf_len && ino)
                jffs2_wbuf_dirties_inode(c, ino);

        ret = 0;
        
exit:
        up_write(&c->wbuf_sem);
        return ret;
}

/*
 *      This is the entry for flash write.
 *      Check, if we work on NAND FLASH, if so build an kvec and write it via vritev
*/
int jffs2_flash_write(struct jffs2_sb_info *c, loff_t ofs, size_t len, size_t *retlen, const u_char *buf)
{
        struct kvec vecs[1];

        if (!jffs2_is_writebuffered(c))
                return c->mtd->write(c->mtd, ofs, len, retlen, buf);

        vecs[0].iov_base = (unsigned char *) buf;
        vecs[0].iov_len = len;
        return jffs2_flash_writev(c, vecs, 1, ofs, retlen, 0);
}

/*
        Handle readback from writebuffer and ECC failure return
*/
int jffs2_flash_read(struct jffs2_sb_info *c, loff_t ofs, size_t len, size_t *retlen, u_char *buf)
{
        loff_t  orbf = 0, owbf = 0, lwbf = 0;
        int     ret;

        if (!jffs2_is_writebuffered(c))
                return c->mtd->read(c->mtd, ofs, len, retlen, buf);

        /* Read flash */
        down_read(&c->wbuf_sem);
        if (jffs2_cleanmarker_oob(c))
                ret = c->mtd->read_ecc(c->mtd, ofs, len, retlen, buf, NULL, c->oobinfo);
        else
                ret = c->mtd->read(c->mtd, ofs, len, retlen, buf);

        if ( (ret == -EBADMSG) && (*retlen == len) ) {
                printk(KERN_WARNING "mtd->read(0x%zx bytes from 0x%llx) returned ECC error\n",
                       len, ofs);
                /* 
                 * We have the raw data without ECC correction in the buffer, maybe 
                 * we are lucky and all data or parts are correct. We check the node.
                 * If data are corrupted node check will sort it out.
                 * We keep this block, it will fail on write or erase and the we
                 * mark it bad. Or should we do that now? But we should give him a chance.
                 * Maybe we had a system crash or power loss before the ecc write or  
                 * a erase was completed.
                 * So we return success. :)
                 */
                ret = 0;
        }       

        /* if no writebuffer available or write buffer empty, return */
        if (!c->wbuf_pagesize || !c->wbuf_len)
                goto exit;

        /* if we read in a different block, return */
        if (SECTOR_ADDR(ofs) != SECTOR_ADDR(c->wbuf_ofs))
                goto exit;

        if (ofs >= c->wbuf_ofs) {
                owbf = (ofs - c->wbuf_ofs);     /* offset in write buffer */
                if (owbf > c->wbuf_len)         /* is read beyond write buffer ? */
                        goto exit;
                lwbf = c->wbuf_len - owbf;      /* number of bytes to copy */
                if (lwbf > len) 
                        lwbf = len;
        } else {        
                orbf = (c->wbuf_ofs - ofs);     /* offset in read buffer */
                if (orbf > len)                 /* is write beyond write buffer ? */
                        goto exit;
                lwbf = len - orbf;              /* number of bytes to copy */
                if (lwbf > c->wbuf_len) 
                        lwbf = c->wbuf_len;
        }       
        if (lwbf > 0)
                memcpy(buf+orbf,c->wbuf+owbf,lwbf);

exit:
        up_read(&c->wbuf_sem);
        return ret;
}

/*
 *      Check, if the out of band area is empty
 */
int jffs2_check_oob_empty( struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb, int mode)
{
        unsigned char *buf;
        int     ret = 0;
        int     i,len,page;
        size_t  retlen;
        int     oob_size;

        /* allocate a buffer for all oob data in this sector */
        oob_size = c->mtd->oobsize;
        len = 4 * oob_size;
        buf = kmalloc(len, GFP_KERNEL);
        if (!buf) {
                printk(KERN_NOTICE "jffs2_check_oob_empty(): allocation of temporary data buffer for oob check failed\n");
                return -ENOMEM;
        }
        /* 
         * if mode = 0, we scan for a total empty oob area, else we have
         * to take care of the cleanmarker in the first page of the block
        */
        ret = jffs2_flash_read_oob(c, jeb->offset, len , &retlen, buf);
        if (ret) {
                D1(printk(KERN_WARNING "jffs2_check_oob_empty(): Read OOB failed %d for block at %08x\n", ret, jeb->offset));
                goto out;
        }
        
        if (retlen < len) {
                D1(printk(KERN_WARNING "jffs2_check_oob_empty(): Read OOB return short read "
                          "(%zd bytes not %d) for block at %08x\n", retlen, len, jeb->offset));
                ret = -EIO;
                goto out;
        }
        
        /* Special check for first page */
        for(i = 0; i < oob_size ; i++) {
                /* Yeah, we know about the cleanmarker. */
                if (mode && i >= c->fsdata_pos && 
                    i < c->fsdata_pos + c->fsdata_len)
                        continue;

                if (buf[i] != 0xFF) {
                        D2(printk(KERN_DEBUG "Found %02x at %x in OOB for %08x\n",
                                  buf[page+i], page+i, jeb->offset));
                        ret = 1; 
                        goto out;
                }
        }

        /* we know, we are aligned :) */        
        for (page = oob_size; page < len; page += sizeof(long)) {
                unsigned long dat = *(unsigned long *)(&buf[page]);
                if(dat != -1) {
                        ret = 1; 
                        goto out;
                }
        }

out:
        kfree(buf);     
        
        return ret;
}

/*
*       Scan for a valid cleanmarker and for bad blocks
*       For virtual blocks (concatenated physical blocks) check the cleanmarker
*       only in the first page of the first physical block, but scan for bad blocks in all
*       physical blocks
*/
int jffs2_check_nand_cleanmarker (struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb)
{
        struct jffs2_unknown_node n;
        unsigned char buf[2 * NAND_MAX_OOBSIZE];
        unsigned char *p;
        int ret, i, cnt, retval = 0;
        size_t retlen, offset;
        int oob_size;

        offset = jeb->offset;
        oob_size = c->mtd->oobsize;

        /* Loop through the physical blocks */
        for (cnt = 0; cnt < (c->sector_size / c->mtd->erasesize); cnt++) {
                /* Check first if the block is bad. */
                if (c->mtd->block_isbad (c->mtd, offset)) {
                        D1 (printk (KERN_WARNING "jffs2_check_nand_cleanmarker(): Bad block at %08x\n", jeb->offset));
                        return 2;
                }
                /*
                   *    We read oob data from page 0 and 1 of the block.
                   *    page 0 contains cleanmarker and badblock info
                   *    page 1 contains failure count of this block
                 */
                ret = c->mtd->read_oob (c->mtd, offset, oob_size << 1, &retlen, buf);

                if (ret) {
                        D1 (printk (KERN_WARNING "jffs2_check_nand_cleanmarker(): Read OOB failed %d for block at %08x\n", ret, jeb->offset));
                        return ret;
                }
                if (retlen < (oob_size << 1)) {
                        D1 (printk (KERN_WARNING "jffs2_check_nand_cleanmarker(): Read OOB return short read (%zd bytes not %d) for block at %08x\n", retlen, oob_size << 1, jeb->offset));
                        return -EIO;
                }

                /* Check cleanmarker only on the first physical block */
                if (!cnt) {
                        n.magic = cpu_to_je16 (JFFS2_MAGIC_BITMASK);
                        n.nodetype = cpu_to_je16 (JFFS2_NODETYPE_CLEANMARKER);
                        n.totlen = cpu_to_je32 (8);
                        p = (unsigned char *) &n;

                        for (i = 0; i < c->fsdata_len; i++) {
                                if (buf[c->fsdata_pos + i] != p[i]) {
                                        retval = 1;
                                }
                        }
                        D1(if (retval == 1) {
                                printk(KERN_WARNING "jffs2_check_nand_cleanmarker(): Cleanmarker node not detected in block at %08x\n", jeb->offset);
                                printk(KERN_WARNING "OOB at %08x was ", offset);
                                for (i=0; i < oob_size; i++) {
                                        printk("%02x ", buf[i]);
                                }
                                printk("\n");
                        })
                }
                offset += c->mtd->erasesize;
        }
        return retval;
}

int jffs2_write_nand_cleanmarker(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb)
{
        struct  jffs2_unknown_node n;
        int     ret;
        size_t  retlen;

        n.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
        n.nodetype = cpu_to_je16(JFFS2_NODETYPE_CLEANMARKER);
        n.totlen = cpu_to_je32(8);

        ret = jffs2_flash_write_oob(c, jeb->offset + c->fsdata_pos, c->fsdata_len, &retlen, (unsigned char *)&n);
        
        if (ret) {
                D1(printk(KERN_WARNING "jffs2_write_nand_cleanmarker(): Write failed for block at %08x: error %d\n", jeb->offset, ret));
                return ret;
        }
        if (retlen != c->fsdata_len) {
                D1(printk(KERN_WARNING "jffs2_write_nand_cleanmarker(): Short write for block at %08x: %zd not %d\n", jeb->offset, retlen, c->fsdata_len));
                return ret;
        }
        return 0;
}

/* 
 * On NAND we try to mark this block bad. If the block was erased more
 * than MAX_ERASE_FAILURES we mark it finaly bad.
 * Don't care about failures. This block remains on the erase-pending
 * or badblock list as long as nobody manipulates the flash with
 * a bootloader or something like that.
 */

int jffs2_write_nand_badblock(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb, uint32_t bad_offset)
{
        int     ret;

        /* if the count is < max, we try to write the counter to the 2nd page oob area */
        if( ++jeb->bad_count < MAX_ERASE_FAILURES)
                return 0;

        if (!c->mtd->block_markbad)
                return 1; // What else can we do?

        D1(printk(KERN_WARNING "jffs2_write_nand_badblock(): Marking bad block at %08x\n", bad_offset));
        ret = c->mtd->block_markbad(c->mtd, bad_offset);
        
        if (ret) {
                D1(printk(KERN_WARNING "jffs2_write_nand_badblock(): Write failed for block at %08x: error %d\n", jeb->offset, ret));
                return ret;
        }
        return 1;
}

#define NAND_JFFS2_OOB16_FSDALEN        8

static struct nand_oobinfo jffs2_oobinfo_docecc = {
        .useecc = MTD_NANDECC_PLACE,
        .eccbytes = 6,
        .eccpos = {0,1,2,3,4,5}
};


static int jffs2_nand_set_oobinfo(struct jffs2_sb_info *c)
{
        struct nand_oobinfo *oinfo = &c->mtd->oobinfo;

        /* Do this only, if we have an oob buffer */
        if (!c->mtd->oobsize)
                return 0;
        
        /* Cleanmarker is out-of-band, so inline size zero */
        c->cleanmarker_size = 0;

        /* Should we use autoplacement ? */
        if (oinfo && oinfo->useecc == MTD_NANDECC_AUTOPLACE) {
                D1(printk(KERN_DEBUG "JFFS2 using autoplace on NAND\n"));
                /* Get the position of the free bytes */
                if (!oinfo->oobfree[0][1]) {
                        printk (KERN_WARNING "jffs2_nand_set_oobinfo(): Eeep. Autoplacement selected and no empty space in oob\n");
                        return -ENOSPC;
                }
                c->fsdata_pos = oinfo->oobfree[0][0];
                c->fsdata_len = oinfo->oobfree[0][1];
                if (c->fsdata_len > 8)
                        c->fsdata_len = 8;
        } else {
                /* This is just a legacy fallback and should go away soon */
                switch(c->mtd->ecctype) {
                case MTD_ECC_RS_DiskOnChip:
                        printk(KERN_WARNING "JFFS2 using DiskOnChip hardware ECC without autoplacement. Fix it!\n");
                        c->oobinfo = &jffs2_oobinfo_docecc;
                        c->fsdata_pos = 6;
                        c->fsdata_len = NAND_JFFS2_OOB16_FSDALEN;
                        c->badblock_pos = 15;
                        break;
        
                default:
                        D1(printk(KERN_DEBUG "JFFS2 on NAND. No autoplacment info found\n"));
                        return -EINVAL;
                }
        }
        return 0;
}

int jffs2_nand_flash_setup(struct jffs2_sb_info *c)
{
        int res;

        /* Initialise write buffer */
        init_rwsem(&c->wbuf_sem);
        c->wbuf_pagesize = c->mtd->oobblock;
        c->wbuf_ofs = 0xFFFFFFFF;
        
        c->wbuf = kmalloc(c->wbuf_pagesize, GFP_KERNEL);
        if (!c->wbuf)
                return -ENOMEM;

        res = jffs2_nand_set_oobinfo(c);

#ifdef BREAKME
        if (!brokenbuf)
                brokenbuf = kmalloc(c->wbuf_pagesize, GFP_KERNEL);
        if (!brokenbuf) {
                kfree(c->wbuf);
                return -ENOMEM;
        }
        memset(brokenbuf, 0xdb, c->wbuf_pagesize);
#endif
        return res;
}

void jffs2_nand_flash_cleanup(struct jffs2_sb_info *c)
{
        kfree(c->wbuf);
}

int jffs2_dataflash_setup(struct jffs2_sb_info *c) {
        c->cleanmarker_size = 0;                /* No cleanmarkers needed */
        
        /* Initialize write buffer */
        init_rwsem(&c->wbuf_sem);
        c->wbuf_pagesize = c->sector_size;
        c->wbuf_ofs = 0xFFFFFFFF;

        c->wbuf = kmalloc(c->wbuf_pagesize, GFP_KERNEL);
        if (!c->wbuf)
                return -ENOMEM;

        printk(KERN_INFO "JFFS2 write-buffering enabled (%i)\n", c->wbuf_pagesize);

        return 0;
}

void jffs2_dataflash_cleanup(struct jffs2_sb_info *c) {
        kfree(c->wbuf);
}

int jffs2_nor_ecc_flash_setup(struct jffs2_sb_info *c) {
        /* Cleanmarker is actually larger on the flashes */
        c->cleanmarker_size = 16;

        /* Initialize write buffer */
        init_rwsem(&c->wbuf_sem);
        c->wbuf_pagesize = c->mtd->eccsize;
        c->wbuf_ofs = 0xFFFFFFFF;

        c->wbuf = kmalloc(c->wbuf_pagesize, GFP_KERNEL);
        if (!c->wbuf)
                return -ENOMEM;

        return 0;
}

void jffs2_nor_ecc_flash_cleanup(struct jffs2_sb_info *c) {
        kfree(c->wbuf);
}