wbuf.c

jffs2源代码基于2。6内核

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

	/* Nothing to do if not NAND flash. In particular, we shouldn't
	   del_timer() the timer we never initialised. */
	if (jffs2_can_mark_obsolete(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 || !c->wbuf_len)
		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) {
		c->wbuf_len = PAD(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 {
			/* Pad with JFFS2_DIRTY_BITMASK */
			memset(c->wbuf + c->wbuf_len, 0, c->wbuf_pagesize - c->wbuf_len);
		}
	}
	/* 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
	ret = c->mtd->write_ecc(c->mtd, c->wbuf_ofs, c->wbuf_pagesize, &retlen, c->wbuf, NULL, c->oobinfo);


	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) {
		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));

	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"));
		ret = __jffs2_flush_wbuf(c, 2);
	} 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);
			ret = __jffs2_flush_wbuf(c, 2);
			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)
{
	return __jffs2_flush_wbuf(c, 1);
}


#define PAGE_DIV(x) ( (x) & (~(c->wbuf_pagesize - 1)) )
#define PAGE_MOD(x) ( (x) & (c->wbuf_pagesize - 1) )
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 (!c->wbuf)
		return jffs2_flash_direct_writev(c, invecs, count, to, retlen);
	
	/* 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);
	}

	/* 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 ( (to & ~(c->sector_size-1)) != (c->wbuf_ofs & ~(c->sector_size-1)) ) {
		/* 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_pad(c);
			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;
				return ret;
			}
		}
		/* 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, 0);
		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;
			return ret;
		}
		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;
		int ret;

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

		/* We did cross a page boundary, so we write some now */
		ret = c->mtd->writev_ecc(c->mtd, outvecs, splitvec+1, outvec_to, &wbuf_retlen, NULL, c->oobinfo); 
		if (ret < 0 || wbuf_retlen != PAGE_DIV(totlen)) {
			/* At this point we have no problem,
			   c->wbuf is empty. 
			*/
			*retlen = donelen;
			return ret;
		}
		
		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;
	}