[MTD] Rework the out of band handling completely

Hopefully the last iteration on this!

The handling of out of band data on NAND was accompanied by tons of fruitless
discussions and halfarsed patches to make it work for a particular
problem. Sufficiently annoyed by I all those "I know it better" mails and the
resonable amount of discarded "it solves my problem" patches, I finally decided
to go for the big rework. After removing the _ecc variants of mtd read/write
functions the solution to satisfy the various requirements was to refactor the
read/write _oob functions in mtd.

The major change is that read/write_oob now takes a pointer to an operation
descriptor structure "struct mtd_oob_ops".instead of having a function with at
least seven arguments.

read/write_oob which should probably renamed to a more descriptive name, can do
the following tasks:

- read/write out of band data
- read/write data content and out of band data
- read/write raw data content and out of band data (ecc disabled)

struct mtd_oob_ops has a mode field, which determines the oob handling mode.

Aside of the MTD_OOB_RAW mode, which is intended to be especially for
diagnostic purposes and some internal functions e.g. bad block table creation,
the other two modes are for mtd clients:

MTD_OOB_PLACE puts/gets the given oob data exactly to/from the place which is
described by the ooboffs and ooblen fields of the mtd_oob_ops strcuture. It's
up to the caller to make sure that the byte positions are not used by the ECC
placement algorithms.

MTD_OOB_AUTO puts/gets the given oob data automaticaly to/from the places in
the out of band area which are described by the oobfree tuples in the ecclayout
data structre which is associated to the devicee.

The decision whether data plus oob or oob only handling is done depends on the
setting of the datbuf member of the data structure. When datbuf == NULL then
the internal read/write_oob functions are selected, otherwise the read/write
data routines are invoked.

Tested on a few platforms with all variants. Please be aware of possible
regressions for your particular device / application scenario

Disclaimer: Any whining will be ignored from those who just contributed "hot
air blurb" and never sat down to tackle the underlying problem of the mess in
the NAND driver grown over time and the big chunk of work to fix up the
existing users. The problem was not the holiness of the existing MTD
interfaces. The problems was the lack of time to go for the big overhaul. It's
easy to add more mess to the existing one, but it takes alot of effort to go
for a real solution.

Improvements and bugfixes are welcome!

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2 files changed, 119 insertions, 112 deletions

diff --git a/fs/jffs2/jffs2_fs_sb.h b/fs/jffs2/jffs2_fs_sb.h
index 506690c..935fec1 100644
--- a/fs/jffs2/jffs2_fs_sb.h
+++ b/fs/jffs2/jffs2_fs_sb.h
@@ -100,6 +100,7 @@ struct jffs2_sb_info {
 #ifdef CONFIG_JFFS2_FS_WRITEBUFFER
 	/* Write-behind buffer for NAND flash */
 	unsigned char *wbuf;
+	unsigned char *oobbuf;
 	uint32_t wbuf_ofs;
 	uint32_t wbuf_len;
 	struct jffs2_inodirty *wbuf_inodes;
diff --git a/fs/jffs2/wbuf.c b/fs/jffs2/wbuf.c
index c6a62e1..1195d06 100644
--- a/fs/jffs2/wbuf.c
+++ b/fs/jffs2/wbuf.c
@@ -955,158 +955,159 @@ exit:
 	return ret;
 }
 
+#define NR_OOB_SCAN_PAGES	4
+
 /*
- *	Check, if the out of band area is empty
+ * 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)
+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);
+	int i, page, ret;
+	int oobsize = c->mtd->oobsize;
+	struct mtd_oob_ops ops;
+
+	ops.len = NR_OOB_SCAN_PAGES * oobsize;
+	ops.ooblen = oobsize;
+	ops.oobbuf = c->oobbuf;
+	ops.ooboffs = 0;
+	ops.datbuf = NULL;
+	ops.mode = MTD_OOB_PLACE;
+
+	ret = c->mtd->read_oob(c->mtd, jeb->offset, &ops);
 	if (ret) {
-		D1(printk(KERN_WARNING "jffs2_check_oob_empty(): Read OOB failed %d for block at %08x\n", ret, jeb->offset));
-		goto out;
+		D1(printk(KERN_WARNING "jffs2_check_oob_empty(): Read OOB "
+			  "failed %d for block at %08x\n", ret, jeb->offset));
+		return ret;
 	}
 
-	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;
+	if (ops.retlen < ops.len) {
+		D1(printk(KERN_WARNING "jffs2_check_oob_empty(): Read OOB "
+			  "returned short read (%zd bytes not %d) for block "
+			  "at %08x\n", ops.retlen, ops.len, jeb->offset));
+		return -EIO;
 	}
 
 	/* Special check for first page */
-	for(i = 0; i < oob_size ; i++) {
+	for(i = 0; i < oobsize ; 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[i], i, jeb->offset));
-			ret = 1;
-			goto out;
+		if (ops.oobbuf[i] != 0xFF) {
+			D2(printk(KERN_DEBUG "Found %02x at %x in OOB for "
+				  "%08x\n", ops.oobbuf[i], i, jeb->offset));
+			return 1;
 		}
 	}
 
 	/* 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;
-		}
+	for (page = oobsize; page < ops.len; page += sizeof(long)) {
+		long dat = *(long *)(&ops.oobbuf[page]);
+		if(dat != -1)
+			return 1;
 	}
-
-out:
-	kfree(buf);
-
-	return ret;
+	return 0;
 }
 
 /*
-*	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)
+ * Scan for a valid cleanmarker and for bad 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);
+	struct mtd_oob_ops ops;
+	int oobsize = c->mtd->oobsize;
+	unsigned char *p,*b;
+	int i, ret;
+	size_t offset = jeb->offset;
+
+	/* 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;
+	}
 
-		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;
-		}
+	ops.len = oobsize;
+	ops.ooblen = oobsize;
+	ops.oobbuf = c->oobbuf;
+	ops.ooboffs = 0;
+	ops.datbuf = NULL;
+	ops.mode = MTD_OOB_PLACE;
 
-		/* 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;
+	ret = c->mtd->read_oob(c->mtd, offset, &ops);
+	if (ret) {
+		D1 (printk(KERN_WARNING "jffs2_check_nand_cleanmarker(): "
+			   "Read OOB failed %d for block at %08x\n",
+			   ret, jeb->offset));
+		return ret;
+	}
 
-			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 %08zx was ", offset);
-				for (i=0; i < oob_size; i++) {
-					printk("%02x ", buf[i]);
-				}
-				printk("\n");
-			})
-		}
-		offset += c->mtd->erasesize;
+	if (ops.retlen < ops.len) {
+		D1 (printk (KERN_WARNING "jffs2_check_nand_cleanmarker(): "
+			    "Read OOB return short read (%zd bytes not %d) "
+			    "for block at %08x\n", ops.retlen, ops.len,
+			    jeb->offset));
+		return -EIO;
 	}
-	return retval;
+
+	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;
+	b = c->oobbuf + c->fsdata_pos;
+
+	for (i = c->fsdata_len; i; i--) {
+		if (*b++ != *p++)
+			ret = 1;
+	}
+
+	D1(if (ret == 1) {
+		printk(KERN_WARNING "jffs2_check_nand_cleanmarker(): "
+		       "Cleanmarker node not detected in block at %08x\n",
+		       offset);
+		printk(KERN_WARNING "OOB at %08zx was ", offset);
+		for (i=0; i < oobsize; i++)
+			printk("%02x ", c->oobbuf[i]);
+		printk("\n");
+	});
+	return ret;
 }
 
-int jffs2_write_nand_cleanmarker(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb)
+int jffs2_write_nand_cleanmarker(struct jffs2_sb_info *c,
+				 struct jffs2_eraseblock *jeb)
 {
-	struct 	jffs2_unknown_node n;
-	int 	ret;
-	size_t 	retlen;
+	struct jffs2_unknown_node n;
+	int	ret;
+	struct mtd_oob_ops ops;
 
 	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);
+	ops.len = c->fsdata_len;
+	ops.ooblen = c->fsdata_len;;
+	ops.oobbuf = (uint8_t *)&n;
+	ops.ooboffs = c->fsdata_pos;
+	ops.datbuf = NULL;
+	ops.mode = MTD_OOB_PLACE;
+
+	ret = c->mtd->write_oob(c->mtd, jeb->offset, &ops);
 
 	if (ret) {
-		D1(printk(KERN_WARNING "jffs2_write_nand_cleanmarker(): Write failed for block at %08x: error %d\n", jeb->offset, 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;
+	if (ops.retlen != ops.len) {
+		D1(printk(KERN_WARNING "jffs2_write_nand_cleanmarker(): "
+			  "Short write for block at %08x: %zd not %d\n",
+			  jeb->offset, ops.retlen, ops.len));
+		return -EIO;
 	}
 	return 0;
 }
@@ -1185,6 +1186,10 @@ int jffs2_nand_flash_setup(struct jffs2_sb_info *c)
 	if (!c->wbuf)
 		return -ENOMEM;
 
+	c->oobbuf = kmalloc(NR_OOB_SCAN_PAGES * c->mtd->oobsize, GFP_KERNEL);
+	if (!c->oobbuf)
+		return -ENOMEM;
+
 	res = jffs2_nand_set_oobinfo(c);
 
 #ifdef BREAKME
@@ -1202,6 +1207,7 @@ int jffs2_nand_flash_setup(struct jffs2_sb_info *c)
 void jffs2_nand_flash_cleanup(struct jffs2_sb_info *c)
 {
 	kfree(c->wbuf);
+	kfree(c->oobbuf);
 }
 
 int jffs2_dataflash_setup(struct jffs2_sb_info *c) {