Patchwork [1/2,MTD,JFFS2] MLC NAND support

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Submitter AYYANARPONNUSAMY GANGHEYAMOORTHY
Date Sept. 19, 2008, 12:37 p.m.
Message ID <30508484.52991221827822859.JavaMail.weblogic@epml16>
Download mbox | patch
Permalink /patch/623/
State Superseded
Headers show

Comments

AYYANARPONNUSAMY GANGHEYAMOORTHY - Sept. 19, 2008, 12:37 p.m.
Currently JFFS2 writes twice to the first page of the block,
cleanmarker in OOB area and data in main area, which prevents
JFFS2 from being used on MLC devices which have NOP count 1.
This patch reserves the first page only for the cleanmarker.

Note : With robustness testing, one test board out six has
given a BUG. We are looking into it.

Signed-off-by: Rajshekar H Payagond <rajshekar.hp@samsung.com>
Jason Liu - Sept. 19, 2008, 2:50 p.m.
Could you send out the panic log? How do you perform the robustness test.
Currently, I found the jffs2 filesystem can't support MLC well. Not
long time ago,
I use the patch JFFS2 doesn't use OOB at MLC NAND/OneNAND from
Kyungmin Park <kyungmin.park at samsung.com> on Sumsung MLC nand flash
K9LAG08U0M, but sometimes i will meet BUG() on the jffs2 file system. I suspect
that that patch does not completely handle MLC nand flash well. How
about this patch?

2008/9/19 AYYANARPONNUSAMY GANGHEYAMOORTHY <moorthy.apg@samsung.com>:
> Currently JFFS2 writes twice to the first page of the block,
> cleanmarker in OOB area and data in main area, which prevents
> JFFS2 from being used on MLC devices which have NOP count 1.
> This patch reserves the first page only for the cleanmarker.
>
> Note : With robustness testing, one test board out six has
> given a BUG. We are looking into it.
>
> Signed-off-by: Rajshekar H Payagond <rajshekar.hp@samsung.com>
> ---
> --- a/fs/jffs2/build.c  2008-08-24 04:48:32.000000000 +0530
> +++ b/fs/jffs2/build.c  2008-09-01 13:39:56.000000000 +0530
> @@ -330,7 +330,11 @@ int jffs2_do_mount_fs(struct jffs2_sb_in
>        int i;
>        int size;
>
> -       c->free_size = c->flash_size;
> +       if (c->mtd->flags == MTD_CAP_MLCNANDFLASH)
> +               c->free_size = 0;
> +       else
> +               c->free_size = c->flash_size;
> +
>        c->nr_blocks = c->flash_size / c->sector_size;
>        size = sizeof(struct jffs2_eraseblock) * c->nr_blocks;
>  #ifndef __ECOS
> @@ -346,7 +350,14 @@ int jffs2_do_mount_fs(struct jffs2_sb_in
>        for (i=0; i<c->nr_blocks; i++) {
>                INIT_LIST_HEAD(&c->blocks[i].list);
>                c->blocks[i].offset = i * c->sector_size;
> -               c->blocks[i].free_size = c->sector_size;
> +               if (c->mtd->flags == MTD_CAP_MLCNANDFLASH) {
> +                       c->blocks[i].free_size =
> +                                       c->sector_size - c->wbuf_pagesize;
> +                       c->blocks[i].used_size = c->wbuf_pagesize;
> +                       c->free_size +=  c->blocks[i].free_size;
> +                       c->used_size += c->blocks[i].used_size;
> +               } else
> +                       c->blocks[i].free_size = c->sector_size;
>        }
>
>        INIT_LIST_HEAD(&c->clean_list);
> --- a/fs/jffs2/debug.c  2008-08-24 04:48:32.000000000 +0530
> +++ b/fs/jffs2/debug.c  2008-09-01 13:39:56.000000000 +0530
> @@ -307,6 +307,9 @@ __jffs2_dbg_acct_paranoia_check_nolock(s
>        uint32_t my_dirty_size = 0;
>        struct jffs2_raw_node_ref *ref2 = jeb->first_node;
>
> +       if (c->mtd->flags == MTD_CAP_MLCNANDFLASH)
> +               my_used_size = c->wbuf_pagesize;
> +
>        while (ref2) {
>                uint32_t totlen = ref_totlen(c, jeb, ref2);
>
> --- a/fs/jffs2/erase.c  2008-08-24 04:48:32.000000000 +0530
> +++ b/fs/jffs2/erase.c  2008-09-01 13:39:56.000000000 +0530
> @@ -454,13 +454,21 @@ static void jffs2_mark_erased_block(stru
>                }
>        }
>        /* Everything else got zeroed before the erase */
> -       jeb->free_size = c->sector_size;
> +       if (c->mtd->flags == MTD_CAP_MLCNANDFLASH) {
> +               jeb->free_size = c->sector_size - c->wbuf_pagesize;
> +               jeb->used_size = c->wbuf_pagesize;
> +       } else
> +               jeb->free_size = c->sector_size;
>
>        mutex_lock(&c->erase_free_sem);
>        spin_lock(&c->erase_completion_lock);
>
>        c->erasing_size -= c->sector_size;
> -       c->free_size += c->sector_size;
> +       if (c->mtd->flags == MTD_CAP_MLCNANDFLASH) {
> +               c->free_size += c->sector_size - c->wbuf_pagesize;
> +               c->used_size += c->wbuf_pagesize;
> +       } else
> +               c->free_size += c->sector_size;
>
>        /* Account for cleanmarker now, if it's in-band */
>        if (c->cleanmarker_size && !jffs2_cleanmarker_oob(c))
> --- a/fs/jffs2/gc.c     2008-08-24 04:48:32.000000000 +0530
> +++ b/fs/jffs2/gc.c     2008-09-01 13:39:56.000000000 +0530
> @@ -237,9 +237,19 @@ int jffs2_garbage_collect_pass(struct jf
>        D1(if (c->nextblock)
>           printk(KERN_DEBUG "Nextblock at  %08x, used_size %08x, dirty_size %08x, wasted_size %08x, free_size %08x\n", c->nextblock->offset, c->nextblock->used_size, c->nextblock->dirty_size, c->nextblock->wasted_size, c->nextblock->free_size));
>
> -       if (!jeb->used_size) {
> -               mutex_unlock(&c->alloc_sem);
> -               goto eraseit;
> +       if (c->mtd->flags == MTD_CAP_MLCNANDFLASH) {
> +               if (jeb->used_size <= c->wbuf_pagesize) {
> +                       mutex_unlock(&c->alloc_sem);
> +                       goto eraseit;
> +               }
> +
> +       }
> +
> +       else{
> +               if (!jeb->used_size) {
> +                       mutex_unlock(&c->alloc_sem);
> +                       goto eraseit;
> +               }
>        }
>
>        raw = jeb->gc_node;
> @@ -429,13 +439,32 @@ int jffs2_garbage_collect_pass(struct jf
>        spin_lock(&c->erase_completion_lock);
>
>  eraseit:
> -       if (c->gcblock && !c->gcblock->used_size) {
> -               D1(printk(KERN_DEBUG "Block at 0x%08x completely obsoleted by GC. Moving to erase_pending_list\n", c->gcblock->offset));
> -               /* We're GC'ing an empty block? */
> -               list_add_tail(&c->gcblock->list, &c->erase_pending_list);
> -               c->gcblock = NULL;
> -               c->nr_erasing_blocks++;
> -               jffs2_erase_pending_trigger(c);
> +       if (c->mtd->flags == MTD_CAP_MLCNANDFLASH) {
> +               if (c->gcblock && (c->gcblock->used_size <= c->wbuf_pagesize)) {
> +                       D1(printk(KERN_DEBUG "Block at 0x%08x completely"
> +                               " obsoleted by GC. Moving to erase_pending_list\n"
> +                               , c->gcblock->offset));
> +                       /* We're GC'ing an empty block? */
> +                       list_add_tail(&c->gcblock->list,
> +                                       &c->erase_pending_list);
> +                       c->gcblock = NULL;
> +                       c->nr_erasing_blocks++;
> +                       jffs2_erase_pending_trigger(c);
> +               }
> +       }
> +
> +       else{
> +               if (c->gcblock && !c->gcblock->used_size) {
> +                       D1(printk(KERN_DEBUG "Block at 0x%08x completely"
> +                               " obsoleted by GC. Moving to erase_pending_list\n"
> +                               , c->gcblock->offset));
> +                       /* We're GC'ing an empty block? */
> +                       list_add_tail(&c->gcblock->list,
> +                                       &c->erase_pending_list);
> +                       c->gcblock = NULL;
> +                       c->nr_erasing_blocks++;
> +                       jffs2_erase_pending_trigger(c);
> +               }
>        }
>        spin_unlock(&c->erase_completion_lock);
>
> --- a/fs/jffs2/nodelist.c       2008-08-24 04:48:32.000000000 +0530
> +++ b/fs/jffs2/nodelist.c       2008-09-01 13:39:56.000000000 +0530
> @@ -634,7 +634,11 @@ struct jffs2_raw_node_ref *jffs2_link_no
>
>        if (!jeb->first_node) {
>                jeb->first_node = ref;
> -               BUG_ON(ref_offset(ref) != jeb->offset);
> +               if (c->mtd->flags == MTD_CAP_MLCNANDFLASH)
> +                       BUG_ON(ref_offset(ref) !=
> +                                               jeb->offset + c->wbuf_pagesize);
> +               else
> +                       BUG_ON(ref_offset(ref) != jeb->offset);
>        } else if (unlikely(ref_offset(ref) != jeb->offset + c->sector_size - jeb->free_size)) {
>                uint32_t last_len = ref_totlen(c, jeb, jeb->last_node);
>
> --- a/fs/jffs2/nodemgmt.c       2008-08-24 04:48:32.000000000 +0530
> +++ b/fs/jffs2/nodemgmt.c       2008-09-01 16:15:47.000000000 +0530
> @@ -362,16 +362,25 @@ static int jffs2_do_reserve_space(struct
>        }
>
>        if (!jeb) {
> -
>                ret = jffs2_find_nextblock(c);
>                if (ret)
>                        return ret;
>
>                jeb = c->nextblock;
> +               if (c->mtd->flags == MTD_CAP_MLCNANDFLASH) {
> +                       if (jeb->free_size != c->sector_size -
> +                               c->cleanmarker_size - c->wbuf_pagesize) {
> +                               printk(KERN_WARNING "Eep. Block 0x%08x taken from free_list had free_size of 0x%08x!!\n", jeb->offset, jeb->free_size);
> +                               goto restart;
> +                       }
> +               }
>
> -               if (jeb->free_size != c->sector_size - c->cleanmarker_size) {
> -                       printk(KERN_WARNING "Eep. Block 0x%08x taken from free_list had free_size of 0x%08x!!\n", jeb->offset, jeb->free_size);
> -                       goto restart;
> +               else{
> +                       if (jeb->free_size != c->sector_size -
> +                                       c->cleanmarker_size) {
> +                               printk(KERN_WARNING "Eep. Block 0x%08x taken from free_list had free_size of 0x%08x!!\n", jeb->offset, jeb->free_size);
> +                               goto restart;
> +                       }
>                }
>        }
>        /* OK, jeb (==c->nextblock) is now pointing at a block which definitely has
> --- a/fs/jffs2/scan.c   2008-08-24 04:48:32.000000000 +0530
> +++ b/fs/jffs2/scan.c   2008-09-01 13:39:56.000000000 +0530
> @@ -534,7 +534,10 @@ static int jffs2_scan_eraseblock (struct
>                }
>        }
>
> -       buf_ofs = jeb->offset;
> +       if (c->mtd->flags == MTD_CAP_MLCNANDFLASH)
> +               buf_ofs = jeb->offset + c->wbuf_pagesize;
> +       else
> +               buf_ofs = jeb->offset;
>
>        if (!buf_size) {
>                /* This is the XIP case -- we're reading _directly_ from the flash chip */
> @@ -582,7 +585,10 @@ static int jffs2_scan_eraseblock (struct
>        }
>
>        /* Now ofs is a complete physical flash offset as it always was... */
> -       ofs += jeb->offset;
> +       if (c->mtd->flags == MTD_CAP_MLCNANDFLASH)
> +               ofs += jeb->offset + c->wbuf_pagesize;
> +       else
> +               ofs += jeb->offset;
>
>        noise = 10;
>
> --- a/fs/jffs2/wbuf.c   2008-08-24 04:48:32.000000000 +0530
> +++ b/fs/jffs2/wbuf.c   2008-09-01 13:39:56.000000000 +0530
> @@ -873,6 +873,13 @@ int jffs2_flash_writev(struct jffs2_sb_i
>                        vlen -= wbuf_retlen;
>                        outvec_to += wbuf_retlen;
>                        c->wbuf_ofs = outvec_to;
> +                       if (c->mtd->flags == MTD_CAP_MLCNANDFLASH) {
> +                               /* adjust write buffer offset,
> +                                * else we get a non contiguous write bug
> +                                */
> +                               if (!(c->wbuf_ofs % c->sector_size))
> +                                       c->wbuf_ofs = 0xffffffff;
> +                       }
>                        donelen += wbuf_retlen;
>                        v += wbuf_retlen;
>                }
> --- a/include/mtd/mtd-abi.h     2008-09-02 13:51:09.000000000 +0530
> +++ b/include/mtd/mtd-abi.h     2008-09-02 13:51:42.000000000 +0530
> @@ -28,12 +28,14 @@ struct mtd_oob_buf {
>  #define MTD_BIT_WRITEABLE      0x800   /* Single bits can be flipped */
>  #define MTD_NO_ERASE           0x1000  /* No erase necessary */
>  #define MTD_POWERUP_LOCK       0x2000  /* Always locked after reset */
> +#define MTD_WRITABLE_ONCE      0x4000
>
>  // Some common devices / combinations of capabilities
>  #define MTD_CAP_ROM            0
>  #define MTD_CAP_RAM            (MTD_WRITEABLE | MTD_BIT_WRITEABLE | MTD_NO_ERASE)
>  #define MTD_CAP_NORFLASH       (MTD_WRITEABLE | MTD_BIT_WRITEABLE)
>  #define MTD_CAP_NANDFLASH      (MTD_WRITEABLE)
> +#define MTD_CAP_MLCNANDFLASH   (MTD_WRITEABLE | MTD_WRITABLE_ONCE)
>
>  /* ECC byte placement */
>  #define MTD_NANDECC_OFF                0       // Switch off ECC (Not recommended)
>
>
>
>
>
> ______________________________________________________
> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/
>
Kyungmin Park - Sept. 22, 2008, 6:33 a.m.
Hi,

On Fri, Sep 19, 2008 at 9:37 PM, AYYANARPONNUSAMY GANGHEYAMOORTHY
<moorthy.apg@samsung.com> wrote:
> Currently JFFS2 writes twice to the first page of the block,
> cleanmarker in OOB area and data in main area, which prevents
> JFFS2 from being used on MLC devices which have NOP count 1.
> This patch reserves the first page only for the cleanmarker.

Is it reasonable to waste the first page at each blocks?
It wastes 1/128 storages e.g., 512MiB/128 = 4MiB.
How about to unuse the oob cleanmarker at previous email sent by me?

I'm not sure why the oob cleanmaker makes a problem at runtime?

And small coding synmatic problem at patche. See below.

Thank you,
Kyungmin Park

> Signed-off-by: Rajshekar H Payagond <rajshekar.hp@samsung.com>
> ---


> --- a/fs/jffs2/gc.c     2008-08-24 04:48:32.000000000 +0530
> +++ b/fs/jffs2/gc.c     2008-09-01 13:39:56.000000000 +0530
> @@ -237,9 +237,19 @@ int jffs2_garbage_collect_pass(struct jf
>        D1(if (c->nextblock)
>           printk(KERN_DEBUG "Nextblock at  %08x, used_size %08x, dirty_size %08x, wasted_size %08x, free_size %08x\n", c->nextblock->offset, c->nextblock->used_size, c->nextblock->dirty_size, c->nextblock->wasted_size, c->nextblock->free_size));
>
> -       if (!jeb->used_size) {
> -               mutex_unlock(&c->alloc_sem);
> -               goto eraseit;
> +       if (c->mtd->flags == MTD_CAP_MLCNANDFLASH) {
> +               if (jeb->used_size <= c->wbuf_pagesize) {
> +                       mutex_unlock(&c->alloc_sem);
> +                       goto eraseit;
> +               }
> +
> +       }
> +
> +       else{
> +               if (!jeb->used_size) {
> +                       mutex_unlock(&c->alloc_sem);
> +                       goto eraseit;
> +               }
>        }

Please add 'else' after curly braces .

>
>        raw = jeb->gc_node;
> @@ -429,13 +439,32 @@ int jffs2_garbage_collect_pass(struct jf
>        spin_lock(&c->erase_completion_lock);
>
>  eraseit:
> -       if (c->gcblock && !c->gcblock->used_size) {
> -               D1(printk(KERN_DEBUG "Block at 0x%08x completely obsoleted by GC. Moving to erase_pending_list\n", c->gcblock->offset));
> -               /* We're GC'ing an empty block? */
> -               list_add_tail(&c->gcblock->list, &c->erase_pending_list);
> -               c->gcblock = NULL;
> -               c->nr_erasing_blocks++;
> -               jffs2_erase_pending_trigger(c);
> +       if (c->mtd->flags == MTD_CAP_MLCNANDFLASH) {
> +               if (c->gcblock && (c->gcblock->used_size <= c->wbuf_pagesize)) {
> +                       D1(printk(KERN_DEBUG "Block at 0x%08x completely"
> +                               " obsoleted by GC. Moving to erase_pending_list\n"
> +                               , c->gcblock->offset));
> +                       /* We're GC'ing an empty block? */
> +                       list_add_tail(&c->gcblock->list,
> +                                       &c->erase_pending_list);
> +                       c->gcblock = NULL;
> +                       c->nr_erasing_blocks++;
> +                       jffs2_erase_pending_trigger(c);
> +               }
> +       }
> +
> +       else{
> +               if (c->gcblock && !c->gcblock->used_size) {
> +                       D1(printk(KERN_DEBUG "Block at 0x%08x completely"
> +                               " obsoleted by GC. Moving to erase_pending_list\n"
> +                               , c->gcblock->offset));
> +                       /* We're GC'ing an empty block? */
> +                       list_add_tail(&c->gcblock->list,
> +                                       &c->erase_pending_list);
> +                       c->gcblock = NULL;
> +                       c->nr_erasing_blocks++;
> +                       jffs2_erase_pending_trigger(c);
> +               }
>        }
>        spin_unlock(&c->erase_completion_lock);

Ditto.



> --- a/include/mtd/mtd-abi.h     2008-09-02 13:51:09.000000000 +0530
> +++ b/include/mtd/mtd-abi.h     2008-09-02 13:51:42.000000000 +0530
> @@ -28,12 +28,14 @@ struct mtd_oob_buf {
>  #define MTD_BIT_WRITEABLE      0x800   /* Single bits can be flipped */
>  #define MTD_NO_ERASE           0x1000  /* No erase necessary */
>  #define MTD_POWERUP_LOCK       0x2000  /* Always locked after reset */
> +#define MTD_WRITABLE_ONCE      0x4000
>
>  // Some common devices / combinations of capabilities
>  #define MTD_CAP_ROM            0
>  #define MTD_CAP_RAM            (MTD_WRITEABLE | MTD_BIT_WRITEABLE | MTD_NO_ERASE)
>  #define MTD_CAP_NORFLASH       (MTD_WRITEABLE | MTD_BIT_WRITEABLE)
>  #define MTD_CAP_NANDFLASH      (MTD_WRITEABLE)
> +#define MTD_CAP_MLCNANDFLASH   (MTD_WRITEABLE | MTD_WRITABLE_ONCE)
>

As previously, define MTD_OOB_WRITEABLE instead of WRITABLE_ONCE.
SLC NAND has WRITEABLE | OOB_WRITEABLE, but MLC NAND has WRITEABLE only

Patch

--- a/fs/jffs2/build.c	2008-08-24 04:48:32.000000000 +0530
+++ b/fs/jffs2/build.c	2008-09-01 13:39:56.000000000 +0530
@@ -330,7 +330,11 @@  int jffs2_do_mount_fs(struct jffs2_sb_in
 	int i;
 	int size;
 
-	c->free_size = c->flash_size;
+	if (c->mtd->flags == MTD_CAP_MLCNANDFLASH)
+		c->free_size = 0;
+	else
+		c->free_size = c->flash_size;
+
 	c->nr_blocks = c->flash_size / c->sector_size;
 	size = sizeof(struct jffs2_eraseblock) * c->nr_blocks;
 #ifndef __ECOS
@@ -346,7 +350,14 @@  int jffs2_do_mount_fs(struct jffs2_sb_in
 	for (i=0; i<c->nr_blocks; i++) {
 		INIT_LIST_HEAD(&c->blocks[i].list);
 		c->blocks[i].offset = i * c->sector_size;
-		c->blocks[i].free_size = c->sector_size;
+		if (c->mtd->flags == MTD_CAP_MLCNANDFLASH) {
+			c->blocks[i].free_size =
+					c->sector_size - c->wbuf_pagesize;
+			c->blocks[i].used_size = c->wbuf_pagesize;
+			c->free_size +=  c->blocks[i].free_size;
+			c->used_size += c->blocks[i].used_size;
+		} else
+			c->blocks[i].free_size = c->sector_size;
 	}
 
 	INIT_LIST_HEAD(&c->clean_list);
--- a/fs/jffs2/debug.c	2008-08-24 04:48:32.000000000 +0530
+++ b/fs/jffs2/debug.c	2008-09-01 13:39:56.000000000 +0530
@@ -307,6 +307,9 @@  __jffs2_dbg_acct_paranoia_check_nolock(s
 	uint32_t my_dirty_size = 0;
 	struct jffs2_raw_node_ref *ref2 = jeb->first_node;
 
+	if (c->mtd->flags == MTD_CAP_MLCNANDFLASH)
+		my_used_size = c->wbuf_pagesize;
+
 	while (ref2) {
 		uint32_t totlen = ref_totlen(c, jeb, ref2);
 
--- a/fs/jffs2/erase.c	2008-08-24 04:48:32.000000000 +0530
+++ b/fs/jffs2/erase.c	2008-09-01 13:39:56.000000000 +0530
@@ -454,13 +454,21 @@  static void jffs2_mark_erased_block(stru
 		}
 	}
 	/* Everything else got zeroed before the erase */
-	jeb->free_size = c->sector_size;
+	if (c->mtd->flags == MTD_CAP_MLCNANDFLASH) {
+		jeb->free_size = c->sector_size - c->wbuf_pagesize;
+		jeb->used_size = c->wbuf_pagesize;
+	} else
+		jeb->free_size = c->sector_size;
 
 	mutex_lock(&c->erase_free_sem);
 	spin_lock(&c->erase_completion_lock);
 
 	c->erasing_size -= c->sector_size;
-	c->free_size += c->sector_size;
+	if (c->mtd->flags == MTD_CAP_MLCNANDFLASH) {
+		c->free_size += c->sector_size - c->wbuf_pagesize;
+		c->used_size += c->wbuf_pagesize;
+	} else
+		c->free_size += c->sector_size;
 
 	/* Account for cleanmarker now, if it's in-band */
 	if (c->cleanmarker_size && !jffs2_cleanmarker_oob(c))
--- a/fs/jffs2/gc.c	2008-08-24 04:48:32.000000000 +0530
+++ b/fs/jffs2/gc.c	2008-09-01 13:39:56.000000000 +0530
@@ -237,9 +237,19 @@  int jffs2_garbage_collect_pass(struct jf
 	D1(if (c->nextblock)
 	   printk(KERN_DEBUG "Nextblock at  %08x, used_size %08x, dirty_size %08x, wasted_size %08x, free_size %08x\n", c->nextblock->offset, c->nextblock->used_size, c->nextblock->dirty_size, c->nextblock->wasted_size, c->nextblock->free_size));
 
-	if (!jeb->used_size) {
-		mutex_unlock(&c->alloc_sem);
-		goto eraseit;
+	if (c->mtd->flags == MTD_CAP_MLCNANDFLASH) {
+		if (jeb->used_size <= c->wbuf_pagesize) {
+			mutex_unlock(&c->alloc_sem);
+			goto eraseit;
+		}
+
+	}
+
+	else{
+		if (!jeb->used_size) {
+			mutex_unlock(&c->alloc_sem);
+			goto eraseit;
+		}
 	}
 
 	raw = jeb->gc_node;
@@ -429,13 +439,32 @@  int jffs2_garbage_collect_pass(struct jf
 	spin_lock(&c->erase_completion_lock);
 
  eraseit:
-	if (c->gcblock && !c->gcblock->used_size) {
-		D1(printk(KERN_DEBUG "Block at 0x%08x completely obsoleted by GC. Moving to erase_pending_list\n", c->gcblock->offset));
-		/* We're GC'ing an empty block? */
-		list_add_tail(&c->gcblock->list, &c->erase_pending_list);
-		c->gcblock = NULL;
-		c->nr_erasing_blocks++;
-		jffs2_erase_pending_trigger(c);
+	if (c->mtd->flags == MTD_CAP_MLCNANDFLASH) {
+		if (c->gcblock && (c->gcblock->used_size <= c->wbuf_pagesize)) {
+			D1(printk(KERN_DEBUG "Block at 0x%08x completely"
+				" obsoleted by GC. Moving to erase_pending_list\n"
+				, c->gcblock->offset));
+			/* We're GC'ing an empty block? */
+			list_add_tail(&c->gcblock->list,
+					&c->erase_pending_list);
+			c->gcblock = NULL;
+			c->nr_erasing_blocks++;
+			jffs2_erase_pending_trigger(c);
+		}
+	}
+
+	else{
+		if (c->gcblock && !c->gcblock->used_size) {
+			D1(printk(KERN_DEBUG "Block at 0x%08x completely"
+				" obsoleted by GC. Moving to erase_pending_list\n"
+				, c->gcblock->offset));
+			/* We're GC'ing an empty block? */
+			list_add_tail(&c->gcblock->list,
+					&c->erase_pending_list);
+			c->gcblock = NULL;
+			c->nr_erasing_blocks++;
+			jffs2_erase_pending_trigger(c);
+		}
 	}
 	spin_unlock(&c->erase_completion_lock);
 
--- a/fs/jffs2/nodelist.c	2008-08-24 04:48:32.000000000 +0530
+++ b/fs/jffs2/nodelist.c	2008-09-01 13:39:56.000000000 +0530
@@ -634,7 +634,11 @@  struct jffs2_raw_node_ref *jffs2_link_no
 
 	if (!jeb->first_node) {
 		jeb->first_node = ref;
-		BUG_ON(ref_offset(ref) != jeb->offset);
+		if (c->mtd->flags == MTD_CAP_MLCNANDFLASH)
+			BUG_ON(ref_offset(ref) !=
+						jeb->offset + c->wbuf_pagesize);
+		else
+			BUG_ON(ref_offset(ref) != jeb->offset);
 	} else if (unlikely(ref_offset(ref) != jeb->offset + c->sector_size - jeb->free_size)) {
 		uint32_t last_len = ref_totlen(c, jeb, jeb->last_node);
 
--- a/fs/jffs2/nodemgmt.c	2008-08-24 04:48:32.000000000 +0530
+++ b/fs/jffs2/nodemgmt.c	2008-09-01 16:15:47.000000000 +0530
@@ -362,16 +362,25 @@  static int jffs2_do_reserve_space(struct
 	}
 
 	if (!jeb) {
-
 		ret = jffs2_find_nextblock(c);
 		if (ret)
 			return ret;
 
 		jeb = c->nextblock;
+		if (c->mtd->flags == MTD_CAP_MLCNANDFLASH) {
+			if (jeb->free_size != c->sector_size -
+				c->cleanmarker_size - c->wbuf_pagesize) {
+				printk(KERN_WARNING "Eep. Block 0x%08x taken from free_list had free_size of 0x%08x!!\n", jeb->offset, jeb->free_size);
+				goto restart;
+			}
+		}
 
-		if (jeb->free_size != c->sector_size - c->cleanmarker_size) {
-			printk(KERN_WARNING "Eep. Block 0x%08x taken from free_list had free_size of 0x%08x!!\n", jeb->offset, jeb->free_size);
-			goto restart;
+		else{
+			if (jeb->free_size != c->sector_size -
+					c->cleanmarker_size) {
+				printk(KERN_WARNING "Eep. Block 0x%08x taken from free_list had free_size of 0x%08x!!\n", jeb->offset, jeb->free_size);
+				goto restart;
+			}
 		}
 	}
 	/* OK, jeb (==c->nextblock) is now pointing at a block which definitely has
--- a/fs/jffs2/scan.c	2008-08-24 04:48:32.000000000 +0530
+++ b/fs/jffs2/scan.c	2008-09-01 13:39:56.000000000 +0530
@@ -534,7 +534,10 @@  static int jffs2_scan_eraseblock (struct
 		}
 	}
 
-	buf_ofs = jeb->offset;
+	if (c->mtd->flags == MTD_CAP_MLCNANDFLASH)
+		buf_ofs = jeb->offset + c->wbuf_pagesize;
+	else
+		buf_ofs = jeb->offset;
 
 	if (!buf_size) {
 		/* This is the XIP case -- we're reading _directly_ from the flash chip */
@@ -582,7 +585,10 @@  static int jffs2_scan_eraseblock (struct
 	}
 
 	/* Now ofs is a complete physical flash offset as it always was... */
-	ofs += jeb->offset;
+	if (c->mtd->flags == MTD_CAP_MLCNANDFLASH)
+		ofs += jeb->offset + c->wbuf_pagesize;
+	else
+		ofs += jeb->offset;
 
 	noise = 10;
 
--- a/fs/jffs2/wbuf.c	2008-08-24 04:48:32.000000000 +0530
+++ b/fs/jffs2/wbuf.c	2008-09-01 13:39:56.000000000 +0530
@@ -873,6 +873,13 @@  int jffs2_flash_writev(struct jffs2_sb_i
 			vlen -= wbuf_retlen;
 			outvec_to += wbuf_retlen;
 			c->wbuf_ofs = outvec_to;
+			if (c->mtd->flags == MTD_CAP_MLCNANDFLASH) {
+				/* adjust write buffer offset,
+				 * else we get a non contiguous write bug
+				 */
+				if (!(c->wbuf_ofs % c->sector_size))
+					c->wbuf_ofs = 0xffffffff;
+			}
 			donelen += wbuf_retlen;
 			v += wbuf_retlen;
 		}
--- a/include/mtd/mtd-abi.h	2008-09-02 13:51:09.000000000 +0530
+++ b/include/mtd/mtd-abi.h	2008-09-02 13:51:42.000000000 +0530
@@ -28,12 +28,14 @@  struct mtd_oob_buf {
 #define MTD_BIT_WRITEABLE	0x800	/* Single bits can be flipped */
 #define MTD_NO_ERASE		0x1000	/* No erase necessary */
 #define MTD_POWERUP_LOCK	0x2000	/* Always locked after reset */
+#define MTD_WRITABLE_ONCE	0x4000
 
 // Some common devices / combinations of capabilities
 #define MTD_CAP_ROM		0
 #define MTD_CAP_RAM		(MTD_WRITEABLE | MTD_BIT_WRITEABLE | MTD_NO_ERASE)
 #define MTD_CAP_NORFLASH	(MTD_WRITEABLE | MTD_BIT_WRITEABLE)
 #define MTD_CAP_NANDFLASH	(MTD_WRITEABLE)
+#define MTD_CAP_MLCNANDFLASH	(MTD_WRITEABLE | MTD_WRITABLE_ONCE)
 
 /* ECC byte placement */
 #define MTD_NANDECC_OFF		0	// Switch off ECC (Not recommended)