[JFFS2] Add erase block summary support (mount time improvement)

The goal of summary is to speed up the mount time. Erase block summary (EBS)
stores summary information at the end of every (closed) erase block. It is
no longer necessary to scan all nodes separetly (and read all pages of them)
just read this "small" summary, where every information is stored which is
needed at mount time.

This summary information is stored in a JFFS2_FEATURE_RWCOMPAT_DELETE. During
the mount process if there is no summary info the orignal scan process will
be executed. EBS works with NAND and NOR flashes, too.

There is a user space tool called sumtool to generate this summary
information for a JFFS2 image.

Signed-off-by: Ferenc Havasi <havasi@inf.u-szeged.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 166 insertions, 84 deletions

diff --git a/fs/jffs2/nodemgmt.c b/fs/jffs2/nodemgmt.c
index fe7e70a4055b..208b2bdf01e5 100644
--- a/fs/jffs2/nodemgmt.c
+++ b/fs/jffs2/nodemgmt.c
@@ -7,7 +7,7 @@
  *
  * For licensing information, see the file 'LICENCE' in this directory.
  *
- * $Id: nodemgmt.c,v 1.124 2005/07/20 15:32:28 dedekind Exp $
+ * $Id: nodemgmt.c,v 1.125 2005/09/07 08:34:54 havasi Exp $
  *
  */
 
@@ -17,6 +17,7 @@
 #include <linux/compiler.h>
 #include <linux/sched.h> /* For cond_resched() */
 #include "nodelist.h"
+#include "debug.h"
 
 /**
  *	jffs2_reserve_space - request physical space to write nodes to flash
@@ -38,9 +39,11 @@
  *	for the requested allocation.
  */
 
-static int jffs2_do_reserve_space(struct jffs2_sb_info *c,  uint32_t minsize, uint32_t *ofs, uint32_t *len);
+static int jffs2_do_reserve_space(struct jffs2_sb_info *c,  uint32_t minsize,
+					uint32_t *ofs, uint32_t *len, uint32_t sumsize);
 
-int jffs2_reserve_space(struct jffs2_sb_info *c, uint32_t minsize, uint32_t *ofs, uint32_t *len, int prio)
+int jffs2_reserve_space(struct jffs2_sb_info *c, uint32_t minsize, uint32_t *ofs,
+			uint32_t *len, int prio, uint32_t sumsize)
 {
 	int ret = -EAGAIN;
 	int blocksneeded = c->resv_blocks_write;
@@ -129,7 +132,7 @@ int jffs2_reserve_space(struct jffs2_sb_info *c, uint32_t minsize, uint32_t *ofs
 			spin_lock(&c->erase_completion_lock);
 		}
 
-		ret = jffs2_do_reserve_space(c, minsize, ofs, len);
+		ret = jffs2_do_reserve_space(c, minsize, ofs, len, sumsize);
 		if (ret) {
 			D1(printk(KERN_DEBUG "jffs2_reserve_space: ret is %d\n", ret));
 		}
@@ -140,7 +143,8 @@ int jffs2_reserve_space(struct jffs2_sb_info *c, uint32_t minsize, uint32_t *ofs
 	return ret;
 }
 
-int jffs2_reserve_space_gc(struct jffs2_sb_info *c, uint32_t minsize, uint32_t *ofs, uint32_t *len)
+int jffs2_reserve_space_gc(struct jffs2_sb_info *c, uint32_t minsize, uint32_t *ofs,
+			uint32_t *len, uint32_t sumsize)
 {
 	int ret = -EAGAIN;
 	minsize = PAD(minsize);
@@ -149,7 +153,7 @@ int jffs2_reserve_space_gc(struct jffs2_sb_info *c, uint32_t minsize, uint32_t *
 
 	spin_lock(&c->erase_completion_lock);
 	while(ret == -EAGAIN) {
-		ret = jffs2_do_reserve_space(c, minsize, ofs, len);
+		ret = jffs2_do_reserve_space(c, minsize, ofs, len, sumsize);
 		if (ret) {
 		        D1(printk(KERN_DEBUG "jffs2_reserve_space_gc: looping, ret is %d\n", ret));
 		}
@@ -158,105 +162,183 @@ int jffs2_reserve_space_gc(struct jffs2_sb_info *c, uint32_t minsize, uint32_t *
 	return ret;
 }
 
-/* Called with alloc sem _and_ erase_completion_lock */
-static int jffs2_do_reserve_space(struct jffs2_sb_info *c,  uint32_t minsize, uint32_t *ofs, uint32_t *len)
+
+/* Classify nextblock (clean, dirty of verydirty) and force to select an other one */
+
+static void jffs2_close_nextblock(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb)
 {
-	struct jffs2_eraseblock *jeb = c->nextblock;
+
+	/* Check, if we have a dirty block now, or if it was dirty already */
+	if (ISDIRTY (jeb->wasted_size + jeb->dirty_size)) {
+		c->dirty_size += jeb->wasted_size;
+		c->wasted_size -= jeb->wasted_size;
+		jeb->dirty_size += jeb->wasted_size;
+		jeb->wasted_size = 0;
+		if (VERYDIRTY(c, jeb->dirty_size)) {
+			D1(printk(KERN_DEBUG "Adding full erase block at 0x%08x to very_dirty_list (free 0x%08x, dirty 0x%08x, used 0x%08x\n",
+			  jeb->offset, jeb->free_size, jeb->dirty_size, jeb->used_size));
+			list_add_tail(&jeb->list, &c->very_dirty_list);
+		} else {
+			D1(printk(KERN_DEBUG "Adding full erase block at 0x%08x to dirty_list (free 0x%08x, dirty 0x%08x, used 0x%08x\n",
+			  jeb->offset, jeb->free_size, jeb->dirty_size, jeb->used_size));
+			list_add_tail(&jeb->list, &c->dirty_list);
+		}
+	} else { 
+		D1(printk(KERN_DEBUG "Adding full erase block at 0x%08x to clean_list (free 0x%08x, dirty 0x%08x, used 0x%08x\n",
+		  jeb->offset, jeb->free_size, jeb->dirty_size, jeb->used_size));
+		list_add_tail(&jeb->list, &c->clean_list);
+	}
+	c->nextblock = NULL;
+
+}
+
+/* Select a new jeb for nextblock */
+
+static int jffs2_find_nextblock(struct jffs2_sb_info *c)
+{
+	struct list_head *next;
 	
- restart:
-	if (jeb && minsize > jeb->free_size) {
-		/* Skip the end of this block and file it as having some dirty space */
-		/* If there's a pending write to it, flush now */
-		if (jffs2_wbuf_dirty(c)) {
+	/* Take the next block off the 'free' list */
+
+	if (list_empty(&c->free_list)) {
+
+		if (!c->nr_erasing_blocks &&
+			!list_empty(&c->erasable_list)) {
+			struct jffs2_eraseblock *ejeb;
+
+			ejeb = list_entry(c->erasable_list.next, struct jffs2_eraseblock, list);
+			list_del(&ejeb->list);
+			list_add_tail(&ejeb->list, &c->erase_pending_list);
+			c->nr_erasing_blocks++;
+			jffs2_erase_pending_trigger(c);
+			D1(printk(KERN_DEBUG "jffs2_find_nextblock: Triggering erase of erasable block at 0x%08x\n",
+				  ejeb->offset));
+		}
+
+		if (!c->nr_erasing_blocks &&
+			!list_empty(&c->erasable_pending_wbuf_list)) {
+			D1(printk(KERN_DEBUG "jffs2_find_nextblock: Flushing write buffer\n"));
+			/* c->nextblock is NULL, no update to c->nextblock allowed */
 			spin_unlock(&c->erase_completion_lock);
-			D1(printk(KERN_DEBUG "jffs2_do_reserve_space: Flushing write buffer\n"));			    
 			jffs2_flush_wbuf_pad(c);
 			spin_lock(&c->erase_completion_lock);
-			jeb = c->nextblock;
-			goto restart;
+			/* Have another go. It'll be on the erasable_list now */
+			return -EAGAIN;
 		}
-		c->wasted_size += jeb->free_size;
-		c->free_size -= jeb->free_size;
-		jeb->wasted_size += jeb->free_size;
-		jeb->free_size = 0;
-		
-		/* Check, if we have a dirty block now, or if it was dirty already */
-		if (ISDIRTY (jeb->wasted_size + jeb->dirty_size)) {
-			c->dirty_size += jeb->wasted_size;
-			c->wasted_size -= jeb->wasted_size;
-			jeb->dirty_size += jeb->wasted_size;
-			jeb->wasted_size = 0;
-			if (VERYDIRTY(c, jeb->dirty_size)) {
-				D1(printk(KERN_DEBUG "Adding full erase block at 0x%08x to very_dirty_list (free 0x%08x, dirty 0x%08x, used 0x%08x\n",
-				  jeb->offset, jeb->free_size, jeb->dirty_size, jeb->used_size));
-				list_add_tail(&jeb->list, &c->very_dirty_list);
-			} else {
-				D1(printk(KERN_DEBUG "Adding full erase block at 0x%08x to dirty_list (free 0x%08x, dirty 0x%08x, used 0x%08x\n",
-				  jeb->offset, jeb->free_size, jeb->dirty_size, jeb->used_size));
-				list_add_tail(&jeb->list, &c->dirty_list);
-			}
-		} else { 
-			D1(printk(KERN_DEBUG "Adding full erase block at 0x%08x to clean_list (free 0x%08x, dirty 0x%08x, used 0x%08x\n",
-			  jeb->offset, jeb->free_size, jeb->dirty_size, jeb->used_size));
-			list_add_tail(&jeb->list, &c->clean_list);
+
+		if (!c->nr_erasing_blocks) {
+			/* Ouch. We're in GC, or we wouldn't have got here.
+			   And there's no space left. At all. */
+			printk(KERN_CRIT "Argh. No free space left for GC. nr_erasing_blocks is %d. nr_free_blocks is %d. (erasableempty: %s, erasingempty: %s, erasependingempty: %s)\n", 
+				   c->nr_erasing_blocks, c->nr_free_blocks, list_empty(&c->erasable_list)?"yes":"no", 
+				   list_empty(&c->erasing_list)?"yes":"no", list_empty(&c->erase_pending_list)?"yes":"no");
+			return -ENOSPC;
 		}
-		c->nextblock = jeb = NULL;
+
+		spin_unlock(&c->erase_completion_lock);
+		/* Don't wait for it; just erase one right now */
+		jffs2_erase_pending_blocks(c, 1);
+		spin_lock(&c->erase_completion_lock);
+
+		/* An erase may have failed, decreasing the
+		   amount of free space available. So we must
+		   restart from the beginning */
+		return -EAGAIN;
 	}
+
+	next = c->free_list.next;
+	list_del(next);
+	c->nextblock = list_entry(next, struct jffs2_eraseblock, list);
+	c->nr_free_blocks--;
 	
-	if (!jeb) {
-		struct list_head *next;
-		/* Take the next block off the 'free' list */
+	jffs2_sum_reset_collected(c->summary); /* reset collected summary */
 
-		if (list_empty(&c->free_list)) {
+	D1(printk(KERN_DEBUG "jffs2_find_nextblock(): new nextblock = 0x%08x\n", c->nextblock->offset));
 
-			if (!c->nr_erasing_blocks && 
-			    !list_empty(&c->erasable_list)) {
-				struct jffs2_eraseblock *ejeb;
+	return 0;
+}
 
-				ejeb = list_entry(c->erasable_list.next, struct jffs2_eraseblock, list);
-				list_del(&ejeb->list);
-				list_add_tail(&ejeb->list, &c->erase_pending_list);
-				c->nr_erasing_blocks++;
-				jffs2_erase_pending_trigger(c);
-				D1(printk(KERN_DEBUG "jffs2_do_reserve_space: Triggering erase of erasable block at 0x%08x\n",
-					  ejeb->offset));
+/* Called with alloc sem _and_ erase_completion_lock */
+static int jffs2_do_reserve_space(struct jffs2_sb_info *c, uint32_t minsize, uint32_t *ofs, uint32_t *len, uint32_t sumsize)
+{
+	struct jffs2_eraseblock *jeb = c->nextblock;
+	uint32_t reserved_size; 			/* for summary information at the end of the jeb */
+	int ret;
+
+ restart:
+	reserved_size = 0;
+
+	if (jffs2_sum_active() && (sumsize != JFFS2_SUMMARY_NOSUM_SIZE)) {
+							/* NOSUM_SIZE means not to generate summary */
+
+		if (jeb) {
+			reserved_size = PAD(sumsize + c->summary->sum_size + JFFS2_SUMMARY_FRAME_SIZE);
+			JFFS2_DBG_SUMMARY("minsize=%d , jeb->free=%d ,"
+						"summary->size=%d , sumsize=%d\n",
+						minsize, jeb->free_size,
+						c->summary->sum_size, sumsize);
+		}
+
+		/* Is there enough space for writing out the current node, or we have to
+		   write out summary information now, close this jeb and select new nextblock? */
+		if (jeb && (PAD(minsize) + PAD(c->summary->sum_size + sumsize +
+					JFFS2_SUMMARY_FRAME_SIZE) > jeb->free_size)) {
+
+			/* Has summary been disabled for this jeb? */
+			if (jffs2_sum_is_disabled(c->summary)) {
+				sumsize = JFFS2_SUMMARY_NOSUM_SIZE;
+				goto restart;
 			}
 
-			if (!c->nr_erasing_blocks && 
-			    !list_empty(&c->erasable_pending_wbuf_list)) {
-				D1(printk(KERN_DEBUG "jffs2_do_reserve_space: Flushing write buffer\n"));
-				/* c->nextblock is NULL, no update to c->nextblock allowed */			    
+			/* Writing out the collected summary information */
+			JFFS2_DBG_SUMMARY("generating summary for 0x%08x.\n", jeb->offset);
+			ret = jffs2_sum_write_sumnode(c);
+
+			if (ret)
+				return ret;
+
+			if (jffs2_sum_is_disabled(c->summary)) {
+				/* jffs2_write_sumnode() couldn't write out the summary information
+				   diabling summary for this jeb and free the collected information
+				 */
+				sumsize = JFFS2_SUMMARY_NOSUM_SIZE;
+				goto restart;
+			}
+
+			jffs2_close_nextblock(c, jeb);
+			jeb = NULL;
+		}
+	} else {
+		if (jeb && minsize > jeb->free_size) {
+			/* Skip the end of this block and file it as having some dirty space */
+			/* If there's a pending write to it, flush now */
+
+			if (jffs2_wbuf_dirty(c)) {
 				spin_unlock(&c->erase_completion_lock);
+				D1(printk(KERN_DEBUG "jffs2_do_reserve_space: Flushing write buffer\n"));
 				jffs2_flush_wbuf_pad(c);
 				spin_lock(&c->erase_completion_lock);
-				/* Have another go. It'll be on the erasable_list now */
-				return -EAGAIN;
-			}
-
-			if (!c->nr_erasing_blocks) {
-				/* Ouch. We're in GC, or we wouldn't have got here.
-				   And there's no space left. At all. */
-				printk(KERN_CRIT "Argh. No free space left for GC. nr_erasing_blocks is %d. nr_free_blocks is %d. (erasableempty: %s, erasingempty: %s, erasependingempty: %s)\n", 
-				       c->nr_erasing_blocks, c->nr_free_blocks, list_empty(&c->erasable_list)?"yes":"no", 
-				       list_empty(&c->erasing_list)?"yes":"no", list_empty(&c->erase_pending_list)?"yes":"no");
-				return -ENOSPC;
+				jeb = c->nextblock;
+				goto restart;
 			}
 
-			spin_unlock(&c->erase_completion_lock);
-			/* Don't wait for it; just erase one right now */
-			jffs2_erase_pending_blocks(c, 1);
-			spin_lock(&c->erase_completion_lock);
+			c->wasted_size += jeb->free_size;
+			c->free_size -= jeb->free_size;
+			jeb->wasted_size += jeb->free_size;
+			jeb->free_size = 0;
 
-			/* An erase may have failed, decreasing the
-			   amount of free space available. So we must
-			   restart from the beginning */
-			return -EAGAIN;
+			jffs2_close_nextblock(c, jeb);
+			jeb = NULL;
 		}
+	}
+
+	if (!jeb) {
+
+		ret = jffs2_find_nextblock(c);
+		if (ret)
+			return ret;
 
-		next = c->free_list.next;
-		list_del(next);
-		c->nextblock = jeb = list_entry(next, struct jffs2_eraseblock, list);
-		c->nr_free_blocks--;
+		jeb = c->nextblock;
 
 		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);
@@ -266,7 +348,7 @@ static int jffs2_do_reserve_space(struct jffs2_sb_info *c,  uint32_t minsize, ui
 	/* OK, jeb (==c->nextblock) is now pointing at a block which definitely has
 	   enough space */
 	*ofs = jeb->offset + (c->sector_size - jeb->free_size);
-	*len = jeb->free_size;
+	*len = jeb->free_size - reserved_size;
 
 	if (c->cleanmarker_size && jeb->used_size == c->cleanmarker_size &&
 	    !jeb->first_node->next_in_ino) {