Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1406 insertions, 0 deletions

diff --git a/fs/jffs2/gc.c b/fs/jffs2/gc.c
new file mode 100644
index 000000000..5c6602f3c
--- /dev/null
+++ b/fs/jffs2/gc.c
@@ -0,0 +1,1406 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright © 2001-2007 Red Hat, Inc.
+ * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
+ *
+ * Created by David Woodhouse <dwmw2@infradead.org>
+ *
+ * For licensing information, see the file 'LICENCE' in this directory.
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/mtd/mtd.h>
+#include <linux/slab.h>
+#include <linux/pagemap.h>
+#include <linux/crc32.h>
+#include <linux/compiler.h>
+#include <linux/stat.h>
+#include "nodelist.h"
+#include "compr.h"
+
+static int jffs2_garbage_collect_pristine(struct jffs2_sb_info *c,
+					  struct jffs2_inode_cache *ic,
+					  struct jffs2_raw_node_ref *raw);
+static int jffs2_garbage_collect_metadata(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
+					struct jffs2_inode_info *f, struct jffs2_full_dnode *fd);
+static int jffs2_garbage_collect_dirent(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
+					struct jffs2_inode_info *f, struct jffs2_full_dirent *fd);
+static int jffs2_garbage_collect_deletion_dirent(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
+					struct jffs2_inode_info *f, struct jffs2_full_dirent *fd);
+static int jffs2_garbage_collect_hole(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
+				      struct jffs2_inode_info *f, struct jffs2_full_dnode *fn,
+				      uint32_t start, uint32_t end);
+static int jffs2_garbage_collect_dnode(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
+				       struct jffs2_inode_info *f, struct jffs2_full_dnode *fn,
+				       uint32_t start, uint32_t end);
+static int jffs2_garbage_collect_live(struct jffs2_sb_info *c,  struct jffs2_eraseblock *jeb,
+			       struct jffs2_raw_node_ref *raw, struct jffs2_inode_info *f);
+
+/* Called with erase_completion_lock held */
+static struct jffs2_eraseblock *jffs2_find_gc_block(struct jffs2_sb_info *c)
+{
+	struct jffs2_eraseblock *ret;
+	struct list_head *nextlist = NULL;
+	int n = jiffies % 128;
+
+	/* Pick an eraseblock to garbage collect next. This is where we'll
+	   put the clever wear-levelling algorithms. Eventually.  */
+	/* We possibly want to favour the dirtier blocks more when the
+	   number of free blocks is low. */
+again:
+	if (!list_empty(&c->bad_used_list) && c->nr_free_blocks > c->resv_blocks_gcbad) {
+		jffs2_dbg(1, "Picking block from bad_used_list to GC next\n");
+		nextlist = &c->bad_used_list;
+	} else if (n < 50 && !list_empty(&c->erasable_list)) {
+		/* Note that most of them will have gone directly to be erased.
+		   So don't favour the erasable_list _too_ much. */
+		jffs2_dbg(1, "Picking block from erasable_list to GC next\n");
+		nextlist = &c->erasable_list;
+	} else if (n < 110 && !list_empty(&c->very_dirty_list)) {
+		/* Most of the time, pick one off the very_dirty list */
+		jffs2_dbg(1, "Picking block from very_dirty_list to GC next\n");
+		nextlist = &c->very_dirty_list;
+	} else if (n < 126 && !list_empty(&c->dirty_list)) {
+		jffs2_dbg(1, "Picking block from dirty_list to GC next\n");
+		nextlist = &c->dirty_list;
+	} else if (!list_empty(&c->clean_list)) {
+		jffs2_dbg(1, "Picking block from clean_list to GC next\n");
+		nextlist = &c->clean_list;
+	} else if (!list_empty(&c->dirty_list)) {
+		jffs2_dbg(1, "Picking block from dirty_list to GC next (clean_list was empty)\n");
+
+		nextlist = &c->dirty_list;
+	} else if (!list_empty(&c->very_dirty_list)) {
+		jffs2_dbg(1, "Picking block from very_dirty_list to GC next (clean_list and dirty_list were empty)\n");
+		nextlist = &c->very_dirty_list;
+	} else if (!list_empty(&c->erasable_list)) {
+		jffs2_dbg(1, "Picking block from erasable_list to GC next (clean_list and {very_,}dirty_list were empty)\n");
+
+		nextlist = &c->erasable_list;
+	} else if (!list_empty(&c->erasable_pending_wbuf_list)) {
+		/* There are blocks are wating for the wbuf sync */
+		jffs2_dbg(1, "Synching wbuf in order to reuse erasable_pending_wbuf_list blocks\n");
+		spin_unlock(&c->erase_completion_lock);
+		jffs2_flush_wbuf_pad(c);
+		spin_lock(&c->erase_completion_lock);
+		goto again;
+	} else {
+		/* Eep. All were empty */
+		jffs2_dbg(1, "No clean, dirty _or_ erasable blocks to GC from! Where are they all?\n");
+		return NULL;
+	}
+
+	ret = list_entry(nextlist->next, struct jffs2_eraseblock, list);
+	list_del(&ret->list);
+	c->gcblock = ret;
+	ret->gc_node = ret->first_node;
+	if (!ret->gc_node) {
+		pr_warn("Eep. ret->gc_node for block at 0x%08x is NULL\n",
+			ret->offset);
+		BUG();
+	}
+
+	/* Have we accidentally picked a clean block with wasted space ? */
+	if (ret->wasted_size) {
+		jffs2_dbg(1, "Converting wasted_size %08x to dirty_size\n",
+			  ret->wasted_size);
+		ret->dirty_size += ret->wasted_size;
+		c->wasted_size -= ret->wasted_size;
+		c->dirty_size += ret->wasted_size;
+		ret->wasted_size = 0;
+	}
+
+	return ret;
+}
+
+/* jffs2_garbage_collect_pass
+ * Make a single attempt to progress GC. Move one node, and possibly
+ * start erasing one eraseblock.
+ */
+int jffs2_garbage_collect_pass(struct jffs2_sb_info *c)
+{
+	struct jffs2_inode_info *f;
+	struct jffs2_inode_cache *ic;
+	struct jffs2_eraseblock *jeb;
+	struct jffs2_raw_node_ref *raw;
+	uint32_t gcblock_dirty;
+	int ret = 0, inum, nlink;
+	int xattr = 0;
+
+	if (mutex_lock_interruptible(&c->alloc_sem))
+		return -EINTR;
+
+
+	for (;;) {
+		/* We can't start doing GC until we've finished checking
+		   the node CRCs etc. */
+		int bucket, want_ino;
+
+		spin_lock(&c->erase_completion_lock);
+		if (!c->unchecked_size)
+			break;
+		spin_unlock(&c->erase_completion_lock);
+
+		if (!xattr)
+			xattr = jffs2_verify_xattr(c);
+
+		spin_lock(&c->inocache_lock);
+		/* Instead of doing the inodes in numeric order, doing a lookup
+		 * in the hash for each possible number, just walk the hash
+		 * buckets of *existing* inodes. This means that we process
+		 * them out-of-order, but it can be a lot faster if there's
+		 * a sparse inode# space. Which there often is. */
+		want_ino = c->check_ino;
+		for (bucket = c->check_ino % c->inocache_hashsize ; bucket < c->inocache_hashsize; bucket++) {
+			for (ic = c->inocache_list[bucket]; ic; ic = ic->next) {
+				if (ic->ino < want_ino)
+					continue;
+
+				if (ic->state != INO_STATE_CHECKEDABSENT &&
+				    ic->state != INO_STATE_PRESENT)
+					goto got_next; /* with inocache_lock held */
+
+				jffs2_dbg(1, "Skipping ino #%u already checked\n",
+					  ic->ino);
+			}
+			want_ino = 0;
+		}
+
+		/* Point c->check_ino past the end of the last bucket. */
+		c->check_ino = ((c->highest_ino + c->inocache_hashsize + 1) &
+				~c->inocache_hashsize) - 1;
+
+		spin_unlock(&c->inocache_lock);
+
+		pr_crit("Checked all inodes but still 0x%x bytes of unchecked space?\n",
+			c->unchecked_size);
+		jffs2_dbg_dump_block_lists_nolock(c);
+		mutex_unlock(&c->alloc_sem);
+		return -ENOSPC;
+
+	got_next:
+		/* For next time round the loop, we want c->checked_ino to indicate
+		 * the *next* one we want to check. And since we're walking the
+		 * buckets rather than doing it sequentially, it's: */
+		c->check_ino = ic->ino + c->inocache_hashsize;
+
+		if (!ic->pino_nlink) {
+			jffs2_dbg(1, "Skipping check of ino #%d with nlink/pino zero\n",
+				  ic->ino);
+			spin_unlock(&c->inocache_lock);
+			jffs2_xattr_delete_inode(c, ic);
+			continue;
+		}
+		switch(ic->state) {
+		case INO_STATE_CHECKEDABSENT:
+		case INO_STATE_PRESENT:
+			spin_unlock(&c->inocache_lock);
+			continue;
+
+		case INO_STATE_GC:
+		case INO_STATE_CHECKING:
+			pr_warn("Inode #%u is in state %d during CRC check phase!\n",
+				ic->ino, ic->state);
+			spin_unlock(&c->inocache_lock);
+			BUG();
+
+		case INO_STATE_READING:
+			/* We need to wait for it to finish, lest we move on
+			   and trigger the BUG() above while we haven't yet
+			   finished checking all its nodes */
+			jffs2_dbg(1, "Waiting for ino #%u to finish reading\n",
+				  ic->ino);
+			/* We need to come back again for the _same_ inode. We've
+			 made no progress in this case, but that should be OK */
+			c->check_ino = ic->ino;
+
+			mutex_unlock(&c->alloc_sem);
+			sleep_on_spinunlock(&c->inocache_wq, &c->inocache_lock);
+			return 0;
+
+		default:
+			BUG();
+
+		case INO_STATE_UNCHECKED:
+			;
+		}
+		ic->state = INO_STATE_CHECKING;
+		spin_unlock(&c->inocache_lock);
+
+		jffs2_dbg(1, "%s(): triggering inode scan of ino#%u\n",
+			  __func__, ic->ino);
+
+		ret = jffs2_do_crccheck_inode(c, ic);
+		if (ret)
+			pr_warn("Returned error for crccheck of ino #%u. Expect badness...\n",
+				ic->ino);
+
+		jffs2_set_inocache_state(c, ic, INO_STATE_CHECKEDABSENT);
+		mutex_unlock(&c->alloc_sem);
+		return ret;
+	}
+
+	/* If there are any blocks which need erasing, erase them now */
+	if (!list_empty(&c->erase_complete_list) ||
+	    !list_empty(&c->erase_pending_list)) {
+		spin_unlock(&c->erase_completion_lock);
+		mutex_unlock(&c->alloc_sem);
+		jffs2_dbg(1, "%s(): erasing pending blocks\n", __func__);
+		if (jffs2_erase_pending_blocks(c, 1))
+			return 0;
+
+		jffs2_dbg(1, "No progress from erasing block; doing GC anyway\n");
+		mutex_lock(&c->alloc_sem);
+		spin_lock(&c->erase_completion_lock);
+	}
+
+	/* First, work out which block we're garbage-collecting */
+	jeb = c->gcblock;
+
+	if (!jeb)
+		jeb = jffs2_find_gc_block(c);
+
+	if (!jeb) {
+		/* Couldn't find a free block. But maybe we can just erase one and make 'progress'? */
+		if (c->nr_erasing_blocks) {
+			spin_unlock(&c->erase_completion_lock);
+			mutex_unlock(&c->alloc_sem);
+			return -EAGAIN;
+		}
+		jffs2_dbg(1, "Couldn't find erase block to garbage collect!\n");
+		spin_unlock(&c->erase_completion_lock);
+		mutex_unlock(&c->alloc_sem);
+		return -EIO;
+	}
+
+	jffs2_dbg(1, "GC from block %08x, used_size %08x, dirty_size %08x, free_size %08x\n",
+		  jeb->offset, jeb->used_size, jeb->dirty_size, jeb->free_size);
+	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;
+	}
+
+	raw = jeb->gc_node;
+	gcblock_dirty = jeb->dirty_size;
+
+	while(ref_obsolete(raw)) {
+		jffs2_dbg(1, "Node at 0x%08x is obsolete... skipping\n",
+			  ref_offset(raw));
+		raw = ref_next(raw);
+		if (unlikely(!raw)) {
+			pr_warn("eep. End of raw list while still supposedly nodes to GC\n");
+			pr_warn("erase block at 0x%08x. free_size 0x%08x, dirty_size 0x%08x, used_size 0x%08x\n",
+				jeb->offset, jeb->free_size,
+				jeb->dirty_size, jeb->used_size);
+			jeb->gc_node = raw;
+			spin_unlock(&c->erase_completion_lock);
+			mutex_unlock(&c->alloc_sem);
+			BUG();
+		}
+	}
+	jeb->gc_node = raw;
+
+	jffs2_dbg(1, "Going to garbage collect node at 0x%08x\n",
+		  ref_offset(raw));
+
+	if (!raw->next_in_ino) {
+		/* Inode-less node. Clean marker, snapshot or something like that */
+		spin_unlock(&c->erase_completion_lock);
+		if (ref_flags(raw) == REF_PRISTINE) {
+			/* It's an unknown node with JFFS2_FEATURE_RWCOMPAT_COPY */
+			jffs2_garbage_collect_pristine(c, NULL, raw);
+		} else {
+			/* Just mark it obsolete */
+			jffs2_mark_node_obsolete(c, raw);
+		}
+		mutex_unlock(&c->alloc_sem);
+		goto eraseit_lock;
+	}
+
+	ic = jffs2_raw_ref_to_ic(raw);
+
+#ifdef CONFIG_JFFS2_FS_XATTR
+	/* When 'ic' refers xattr_datum/xattr_ref, this node is GCed as xattr.
+	 * We can decide whether this node is inode or xattr by ic->class.     */
+	if (ic->class == RAWNODE_CLASS_XATTR_DATUM
+	    || ic->class == RAWNODE_CLASS_XATTR_REF) {
+		spin_unlock(&c->erase_completion_lock);
+
+		if (ic->class == RAWNODE_CLASS_XATTR_DATUM) {
+			ret = jffs2_garbage_collect_xattr_datum(c, (struct jffs2_xattr_datum *)ic, raw);
+		} else {
+			ret = jffs2_garbage_collect_xattr_ref(c, (struct jffs2_xattr_ref *)ic, raw);
+		}
+		goto test_gcnode;
+	}
+#endif
+
+	/* We need to hold the inocache. Either the erase_completion_lock or
+	   the inocache_lock are sufficient; we trade down since the inocache_lock
+	   causes less contention. */
+	spin_lock(&c->inocache_lock);
+
+	spin_unlock(&c->erase_completion_lock);
+
+	jffs2_dbg(1, "%s(): collecting from block @0x%08x. Node @0x%08x(%d), ino #%u\n",
+		  __func__, jeb->offset, ref_offset(raw), ref_flags(raw),
+		  ic->ino);
+
+	/* Three possibilities:
+	   1. Inode is already in-core. We must iget it and do proper
+	      updating to its fragtree, etc.
+	   2. Inode is not in-core, node is REF_PRISTINE. We lock the
+	      inocache to prevent a read_inode(), copy the node intact.
+	   3. Inode is not in-core, node is not pristine. We must iget()
+	      and take the slow path.
+	*/
+
+	switch(ic->state) {
+	case INO_STATE_CHECKEDABSENT:
+		/* It's been checked, but it's not currently in-core.
+		   We can just copy any pristine nodes, but have
+		   to prevent anyone else from doing read_inode() while
+		   we're at it, so we set the state accordingly */
+		if (ref_flags(raw) == REF_PRISTINE)
+			ic->state = INO_STATE_GC;
+		else {
+			jffs2_dbg(1, "Ino #%u is absent but node not REF_PRISTINE. Reading.\n",
+				  ic->ino);
+		}
+		break;
+
+	case INO_STATE_PRESENT:
+		/* It's in-core. GC must iget() it. */
+		break;
+
+	case INO_STATE_UNCHECKED:
+	case INO_STATE_CHECKING:
+	case INO_STATE_GC:
+		/* Should never happen. We should have finished checking
+		   by the time we actually start doing any GC, and since
+		   we're holding the alloc_sem, no other garbage collection
+		   can happen.
+		*/
+		pr_crit("Inode #%u already in state %d in jffs2_garbage_collect_pass()!\n",
+			ic->ino, ic->state);
+		mutex_unlock(&c->alloc_sem);
+		spin_unlock(&c->inocache_lock);
+		BUG();
+
+	case INO_STATE_READING:
+		/* Someone's currently trying to read it. We must wait for
+		   them to finish and then go through the full iget() route
+		   to do the GC. However, sometimes read_inode() needs to get
+		   the alloc_sem() (for marking nodes invalid) so we must
+		   drop the alloc_sem before sleeping. */
+
+		mutex_unlock(&c->alloc_sem);
+		jffs2_dbg(1, "%s(): waiting for ino #%u in state %d\n",
+			  __func__, ic->ino, ic->state);
+		sleep_on_spinunlock(&c->inocache_wq, &c->inocache_lock);
+		/* And because we dropped the alloc_sem we must start again from the
+		   beginning. Ponder chance of livelock here -- we're returning success
+		   without actually making any progress.
+
+		   Q: What are the chances that the inode is back in INO_STATE_READING
+		   again by the time we next enter this function? And that this happens
+		   enough times to cause a real delay?
+
+		   A: Small enough that I don't care :)
+		*/
+		return 0;
+	}
+
+	/* OK. Now if the inode is in state INO_STATE_GC, we are going to copy the
+	   node intact, and we don't have to muck about with the fragtree etc.
+	   because we know it's not in-core. If it _was_ in-core, we go through
+	   all the iget() crap anyway */
+
+	if (ic->state == INO_STATE_GC) {
+		spin_unlock(&c->inocache_lock);
+
+		ret = jffs2_garbage_collect_pristine(c, ic, raw);
+
+		spin_lock(&c->inocache_lock);
+		ic->state = INO_STATE_CHECKEDABSENT;
+		wake_up(&c->inocache_wq);
+
+		if (ret != -EBADFD) {
+			spin_unlock(&c->inocache_lock);
+			goto test_gcnode;
+		}
+
+		/* Fall through if it wanted us to, with inocache_lock held */
+	}
+
+	/* Prevent the fairly unlikely race where the gcblock is
+	   entirely obsoleted by the final close of a file which had
+	   the only valid nodes in the block, followed by erasure,
+	   followed by freeing of the ic because the erased block(s)
+	   held _all_ the nodes of that inode.... never been seen but
+	   it's vaguely possible. */
+
+	inum = ic->ino;
+	nlink = ic->pino_nlink;
+	spin_unlock(&c->inocache_lock);
+
+	f = jffs2_gc_fetch_inode(c, inum, !nlink);
+	if (IS_ERR(f)) {
+		ret = PTR_ERR(f);
+		goto release_sem;
+	}
+	if (!f) {
+		ret = 0;
+		goto release_sem;
+	}
+
+	ret = jffs2_garbage_collect_live(c, jeb, raw, f);
+
+	jffs2_gc_release_inode(c, f);
+
+ test_gcnode:
+	if (jeb->dirty_size == gcblock_dirty && !ref_obsolete(jeb->gc_node)) {
+		/* Eep. This really should never happen. GC is broken */
+		pr_err("Error garbage collecting node at %08x!\n",
+		       ref_offset(jeb->gc_node));
+		ret = -ENOSPC;
+	}
+ release_sem:
+	mutex_unlock(&c->alloc_sem);
+
+ eraseit_lock:
+	/* If we've finished this block, start it erasing */
+	spin_lock(&c->erase_completion_lock);
+
+ eraseit:
+	if (c->gcblock && !c->gcblock->used_size) {
+		jffs2_dbg(1, "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_garbage_collect_trigger(c);
+	}
+	spin_unlock(&c->erase_completion_lock);
+
+	return ret;
+}
+
+static int jffs2_garbage_collect_live(struct jffs2_sb_info *c,  struct jffs2_eraseblock *jeb,
+				      struct jffs2_raw_node_ref *raw, struct jffs2_inode_info *f)
+{
+	struct jffs2_node_frag *frag;
+	struct jffs2_full_dnode *fn = NULL;
+	struct jffs2_full_dirent *fd;
+	uint32_t start = 0, end = 0, nrfrags = 0;
+	int ret = 0;
+
+	mutex_lock(&f->sem);
+
+	/* Now we have the lock for this inode. Check that it's still the one at the head
+	   of the list. */
+
+	spin_lock(&c->erase_completion_lock);
+
+	if (c->gcblock != jeb) {
+		spin_unlock(&c->erase_completion_lock);
+		jffs2_dbg(1, "GC block is no longer gcblock. Restart\n");
+		goto upnout;
+	}
+	if (ref_obsolete(raw)) {
+		spin_unlock(&c->erase_completion_lock);
+		jffs2_dbg(1, "node to be GC'd was obsoleted in the meantime.\n");
+		/* They'll call again */
+		goto upnout;
+	}
+	spin_unlock(&c->erase_completion_lock);
+
+	/* OK. Looks safe. And nobody can get us now because we have the semaphore. Move the block */
+	if (f->metadata && f->metadata->raw == raw) {
+		fn = f->metadata;
+		ret = jffs2_garbage_collect_metadata(c, jeb, f, fn);
+		goto upnout;
+	}
+
+	/* FIXME. Read node and do lookup? */
+	for (frag = frag_first(&f->fragtree); frag; frag = frag_next(frag)) {
+		if (frag->node && frag->node->raw == raw) {
+			fn = frag->node;
+			end = frag->ofs + frag->size;
+			if (!nrfrags++)
+				start = frag->ofs;
+			if (nrfrags == frag->node->frags)
+				break; /* We've found them all */
+		}
+	}
+	if (fn) {
+		if (ref_flags(raw) == REF_PRISTINE) {
+			ret = jffs2_garbage_collect_pristine(c, f->inocache, raw);
+			if (!ret) {
+				/* Urgh. Return it sensibly. */
+				frag->node->raw = f->inocache->nodes;
+			}
+			if (ret != -EBADFD)
+				goto upnout;
+		}
+		/* We found a datanode. Do the GC */
+		if((start >> PAGE_SHIFT) < ((end-1) >> PAGE_SHIFT)) {
+			/* It crosses a page boundary. Therefore, it must be a hole. */
+			ret = jffs2_garbage_collect_hole(c, jeb, f, fn, start, end);
+		} else {
+			/* It could still be a hole. But we GC the page this way anyway */
+			ret = jffs2_garbage_collect_dnode(c, jeb, f, fn, start, end);
+		}
+		goto upnout;
+	}
+
+	/* Wasn't a dnode. Try dirent */
+	for (fd = f->dents; fd; fd=fd->next) {
+		if (fd->raw == raw)
+			break;
+	}
+
+	if (fd && fd->ino) {
+		ret = jffs2_garbage_collect_dirent(c, jeb, f, fd);
+	} else if (fd) {
+		ret = jffs2_garbage_collect_deletion_dirent(c, jeb, f, fd);
+	} else {
+		pr_warn("Raw node at 0x%08x wasn't in node lists for ino #%u\n",
+			ref_offset(raw), f->inocache->ino);
+		if (ref_obsolete(raw)) {
+			pr_warn("But it's obsolete so we don't mind too much\n");
+		} else {
+			jffs2_dbg_dump_node(c, ref_offset(raw));
+			BUG();
+		}
+	}
+ upnout:
+	mutex_unlock(&f->sem);
+
+	return ret;
+}
+
+static int jffs2_garbage_collect_pristine(struct jffs2_sb_info *c,
+					  struct jffs2_inode_cache *ic,
+					  struct jffs2_raw_node_ref *raw)
+{
+	union jffs2_node_union *node;
+	size_t retlen;
+	int ret;
+	uint32_t phys_ofs, alloclen;
+	uint32_t crc, rawlen;
+	int retried = 0;
+
+	jffs2_dbg(1, "Going to GC REF_PRISTINE node at 0x%08x\n",
+		  ref_offset(raw));
+
+	alloclen = rawlen = ref_totlen(c, c->gcblock, raw);
+
+	/* Ask for a small amount of space (or the totlen if smaller) because we
+	   don't want to force wastage of the end of a block if splitting would
+	   work. */
+	if (ic && alloclen > sizeof(struct jffs2_raw_inode) + JFFS2_MIN_DATA_LEN)
+		alloclen = sizeof(struct jffs2_raw_inode) + JFFS2_MIN_DATA_LEN;
+
+	ret = jffs2_reserve_space_gc(c, alloclen, &alloclen, rawlen);
+	/* 'rawlen' is not the exact summary size; it is only an upper estimation */
+
+	if (ret)
+		return ret;
+
+	if (alloclen < rawlen) {
+		/* Doesn't fit untouched. We'll go the old route and split it */
+		return -EBADFD;
+	}
+
+	node = kmalloc(rawlen, GFP_KERNEL);
+	if (!node)
+		return -ENOMEM;
+
+	ret = jffs2_flash_read(c, ref_offset(raw), rawlen, &retlen, (char *)node);
+	if (!ret && retlen != rawlen)
+		ret = -EIO;
+	if (ret)
+		goto out_node;
+
+	crc = crc32(0, node, sizeof(struct jffs2_unknown_node)-4);
+	if (je32_to_cpu(node->u.hdr_crc) != crc) {
+		pr_warn("Header CRC failed on REF_PRISTINE node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
+			ref_offset(raw), je32_to_cpu(node->u.hdr_crc), crc);
+		goto bail;
+	}
+
+	switch(je16_to_cpu(node->u.nodetype)) {
+	case JFFS2_NODETYPE_INODE:
+		crc = crc32(0, node, sizeof(node->i)-8);
+		if (je32_to_cpu(node->i.node_crc) != crc) {
+			pr_warn("Node CRC failed on REF_PRISTINE data node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
+				ref_offset(raw), je32_to_cpu(node->i.node_crc),
+				crc);
+			goto bail;
+		}
+
+		if (je32_to_cpu(node->i.dsize)) {
+			crc = crc32(0, node->i.data, je32_to_cpu(node->i.csize));
+			if (je32_to_cpu(node->i.data_crc) != crc) {
+				pr_warn("Data CRC failed on REF_PRISTINE data node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
+					ref_offset(raw),
+					je32_to_cpu(node->i.data_crc), crc);
+				goto bail;
+			}
+		}
+		break;
+
+	case JFFS2_NODETYPE_DIRENT:
+		crc = crc32(0, node, sizeof(node->d)-8);
+		if (je32_to_cpu(node->d.node_crc) != crc) {
+			pr_warn("Node CRC failed on REF_PRISTINE dirent node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
+				ref_offset(raw),
+				je32_to_cpu(node->d.node_crc), crc);
+			goto bail;
+		}
+
+		if (strnlen(node->d.name, node->d.nsize) != node->d.nsize) {
+			pr_warn("Name in dirent node at 0x%08x contains zeroes\n",
+				ref_offset(raw));
+			goto bail;
+		}
+
+		if (node->d.nsize) {
+			crc = crc32(0, node->d.name, node->d.nsize);
+			if (je32_to_cpu(node->d.name_crc) != crc) {
+				pr_warn("Name CRC failed on REF_PRISTINE dirent node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
+					ref_offset(raw),
+					je32_to_cpu(node->d.name_crc), crc);
+				goto bail;
+			}
+		}
+		break;
+	default:
+		/* If it's inode-less, we don't _know_ what it is. Just copy it intact */
+		if (ic) {
+			pr_warn("Unknown node type for REF_PRISTINE node at 0x%08x: 0x%04x\n",
+				ref_offset(raw), je16_to_cpu(node->u.nodetype));
+			goto bail;
+		}
+	}
+
+	/* OK, all the CRCs are good; this node can just be copied as-is. */
+ retry:
+	phys_ofs = write_ofs(c);
+
+	ret = jffs2_flash_write(c, phys_ofs, rawlen, &retlen, (char *)node);
+
+	if (ret || (retlen != rawlen)) {
+		pr_notice("Write of %d bytes at 0x%08x failed. returned %d, retlen %zd\n",
+			  rawlen, phys_ofs, ret, retlen);
+		if (retlen) {
+			jffs2_add_physical_node_ref(c, phys_ofs | REF_OBSOLETE, rawlen, NULL);
+		} else {
+			pr_notice("Not marking the space at 0x%08x as dirty because the flash driver returned retlen zero\n",
+				  phys_ofs);
+		}
+		if (!retried) {
+			/* Try to reallocate space and retry */
+			uint32_t dummy;
+			struct jffs2_eraseblock *jeb = &c->blocks[phys_ofs / c->sector_size];
+
+			retried = 1;
+
+			jffs2_dbg(1, "Retrying failed write of REF_PRISTINE node.\n");
+
+			jffs2_dbg_acct_sanity_check(c,jeb);
+			jffs2_dbg_acct_paranoia_check(c, jeb);
+
+			ret = jffs2_reserve_space_gc(c, rawlen, &dummy, rawlen);
+						/* this is not the exact summary size of it,
+							it is only an upper estimation */
+
+			if (!ret) {
+				jffs2_dbg(1, "Allocated space at 0x%08x to retry failed write.\n",
+					  phys_ofs);
+
+				jffs2_dbg_acct_sanity_check(c,jeb);
+				jffs2_dbg_acct_paranoia_check(c, jeb);
+
+				goto retry;
+			}
+			jffs2_dbg(1, "Failed to allocate space to retry failed write: %d!\n",
+				  ret);
+		}
+
+		if (!ret)
+			ret = -EIO;
+		goto out_node;
+	}
+	jffs2_add_physical_node_ref(c, phys_ofs | REF_PRISTINE, rawlen, ic);
+
+	jffs2_mark_node_obsolete(c, raw);
+	jffs2_dbg(1, "WHEEE! GC REF_PRISTINE node at 0x%08x succeeded\n",
+		  ref_offset(raw));
+
+ out_node:
+	kfree(node);
+	return ret;
+ bail:
+	ret = -EBADFD;
+	goto out_node;
+}
+
+static int jffs2_garbage_collect_metadata(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
+					struct jffs2_inode_info *f, struct jffs2_full_dnode *fn)
+{
+	struct jffs2_full_dnode *new_fn;
+	struct jffs2_raw_inode ri;
+	struct jffs2_node_frag *last_frag;
+	union jffs2_device_node dev;
+	char *mdata = NULL;
+	int mdatalen = 0;
+	uint32_t alloclen, ilen;
+	int ret;
+
+	if (S_ISBLK(JFFS2_F_I_MODE(f)) ||
+	    S_ISCHR(JFFS2_F_I_MODE(f)) ) {
+		/* For these, we don't actually need to read the old node */
+		mdatalen = jffs2_encode_dev(&dev, JFFS2_F_I_RDEV(f));
+		mdata = (char *)&dev;
+		jffs2_dbg(1, "%s(): Writing %d bytes of kdev_t\n",
+			  __func__, mdatalen);
+	} else if (S_ISLNK(JFFS2_F_I_MODE(f))) {
+		mdatalen = fn->size;
+		mdata = kmalloc(fn->size, GFP_KERNEL);
+		if (!mdata) {
+			pr_warn("kmalloc of mdata failed in jffs2_garbage_collect_metadata()\n");
+			return -ENOMEM;
+		}
+		ret = jffs2_read_dnode(c, f, fn, mdata, 0, mdatalen);
+		if (ret) {
+			pr_warn("read of old metadata failed in jffs2_garbage_collect_metadata(): %d\n",
+				ret);
+			kfree(mdata);
+			return ret;
+		}
+		jffs2_dbg(1, "%s(): Writing %d bites of symlink target\n",
+			  __func__, mdatalen);
+
+	}
+
+	ret = jffs2_reserve_space_gc(c, sizeof(ri) + mdatalen, &alloclen,
+				JFFS2_SUMMARY_INODE_SIZE);
+	if (ret) {
+		pr_warn("jffs2_reserve_space_gc of %zd bytes for garbage_collect_metadata failed: %d\n",
+			sizeof(ri) + mdatalen, ret);
+		goto out;
+	}
+
+	last_frag = frag_last(&f->fragtree);
+	if (last_frag)
+		/* Fetch the inode length from the fragtree rather then
+		 * from i_size since i_size may have not been updated yet */
+		ilen = last_frag->ofs + last_frag->size;
+	else
+		ilen = JFFS2_F_I_SIZE(f);
+
+	memset(&ri, 0, sizeof(ri));
+	ri.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
+	ri.nodetype = cpu_to_je16(JFFS2_NODETYPE_INODE);
+	ri.totlen = cpu_to_je32(sizeof(ri) + mdatalen);
+	ri.hdr_crc = cpu_to_je32(crc32(0, &ri, sizeof(struct jffs2_unknown_node)-4));
+
+	ri.ino = cpu_to_je32(f->inocache->ino);
+	ri.version = cpu_to_je32(++f->highest_version);
+	ri.mode = cpu_to_jemode(JFFS2_F_I_MODE(f));
+	ri.uid = cpu_to_je16(JFFS2_F_I_UID(f));
+	ri.gid = cpu_to_je16(JFFS2_F_I_GID(f));
+	ri.isize = cpu_to_je32(ilen);
+	ri.atime = cpu_to_je32(JFFS2_F_I_ATIME(f));
+	ri.ctime = cpu_to_je32(JFFS2_F_I_CTIME(f));
+	ri.mtime = cpu_to_je32(JFFS2_F_I_MTIME(f));
+	ri.offset = cpu_to_je32(0);
+	ri.csize = cpu_to_je32(mdatalen);
+	ri.dsize = cpu_to_je32(mdatalen);
+	ri.compr = JFFS2_COMPR_NONE;
+	ri.node_crc = cpu_to_je32(crc32(0, &ri, sizeof(ri)-8));
+	ri.data_crc = cpu_to_je32(crc32(0, mdata, mdatalen));
+
+	new_fn = jffs2_write_dnode(c, f, &ri, mdata, mdatalen, ALLOC_GC);
+
+	if (IS_ERR(new_fn)) {
+		pr_warn("Error writing new dnode: %ld\n", PTR_ERR(new_fn));
+		ret = PTR_ERR(new_fn);
+		goto out;
+	}
+	jffs2_mark_node_obsolete(c, fn->raw);
+	jffs2_free_full_dnode(fn);
+	f->metadata = new_fn;
+ out:
+	if (S_ISLNK(JFFS2_F_I_MODE(f)))
+		kfree(mdata);
+	return ret;
+}
+
+static int jffs2_garbage_collect_dirent(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
+					struct jffs2_inode_info *f, struct jffs2_full_dirent *fd)
+{
+	struct jffs2_full_dirent *new_fd;
+	struct jffs2_raw_dirent rd;
+	uint32_t alloclen;
+	int ret;
+
+	rd.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
+	rd.nodetype = cpu_to_je16(JFFS2_NODETYPE_DIRENT);
+	rd.nsize = strlen(fd->name);
+	rd.totlen = cpu_to_je32(sizeof(rd) + rd.nsize);
+	rd.hdr_crc = cpu_to_je32(crc32(0, &rd, sizeof(struct jffs2_unknown_node)-4));
+
+	rd.pino = cpu_to_je32(f->inocache->ino);
+	rd.version = cpu_to_je32(++f->highest_version);
+	rd.ino = cpu_to_je32(fd->ino);
+	/* If the times on this inode were set by explicit utime() they can be different,
+	   so refrain from splatting them. */
+	if (JFFS2_F_I_MTIME(f) == JFFS2_F_I_CTIME(f))
+		rd.mctime = cpu_to_je32(JFFS2_F_I_MTIME(f));
+	else
+		rd.mctime = cpu_to_je32(0);
+	rd.type = fd->type;
+	rd.node_crc = cpu_to_je32(crc32(0, &rd, sizeof(rd)-8));
+	rd.name_crc = cpu_to_je32(crc32(0, fd->name, rd.nsize));
+
+	ret = jffs2_reserve_space_gc(c, sizeof(rd)+rd.nsize, &alloclen,
+				JFFS2_SUMMARY_DIRENT_SIZE(rd.nsize));
+	if (ret) {
+		pr_warn("jffs2_reserve_space_gc of %zd bytes for garbage_collect_dirent failed: %d\n",
+			sizeof(rd)+rd.nsize, ret);
+		return ret;
+	}
+	new_fd = jffs2_write_dirent(c, f, &rd, fd->name, rd.nsize, ALLOC_GC);
+
+	if (IS_ERR(new_fd)) {
+		pr_warn("jffs2_write_dirent in garbage_collect_dirent failed: %ld\n",
+			PTR_ERR(new_fd));
+		return PTR_ERR(new_fd);
+	}
+	jffs2_add_fd_to_list(c, new_fd, &f->dents);
+	return 0;
+}
+
+static int jffs2_garbage_collect_deletion_dirent(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
+					struct jffs2_inode_info *f, struct jffs2_full_dirent *fd)
+{
+	struct jffs2_full_dirent **fdp = &f->dents;
+	int found = 0;
+
+	/* On a medium where we can't actually mark nodes obsolete
+	   pernamently, such as NAND flash, we need to work out
+	   whether this deletion dirent is still needed to actively
+	   delete a 'real' dirent with the same name that's still
+	   somewhere else on the flash. */
+	if (!jffs2_can_mark_obsolete(c)) {
+		struct jffs2_raw_dirent *rd;
+		struct jffs2_raw_node_ref *raw;
+		int ret;
+		size_t retlen;
+		int name_len = strlen(fd->name);
+		uint32_t name_crc = crc32(0, fd->name, name_len);
+		uint32_t rawlen = ref_totlen(c, jeb, fd->raw);
+
+		rd = kmalloc(rawlen, GFP_KERNEL);
+		if (!rd)
+			return -ENOMEM;
+
+		/* Prevent the erase code from nicking the obsolete node refs while
+		   we're looking at them. I really don't like this extra lock but
+		   can't see any alternative. Suggestions on a postcard to... */
+		mutex_lock(&c->erase_free_sem);
+
+		for (raw = f->inocache->nodes; raw != (void *)f->inocache; raw = raw->next_in_ino) {
+
+			cond_resched();
+
+			/* We only care about obsolete ones */
+			if (!(ref_obsolete(raw)))
+				continue;
+
+			/* Any dirent with the same name is going to have the same length... */
+			if (ref_totlen(c, NULL, raw) != rawlen)
+				continue;
+
+			/* Doesn't matter if there's one in the same erase block. We're going to
+			   delete it too at the same time. */
+			if (SECTOR_ADDR(raw->flash_offset) == SECTOR_ADDR(fd->raw->flash_offset))
+				continue;
+
+			jffs2_dbg(1, "Check potential deletion dirent at %08x\n",
+				  ref_offset(raw));
+
+			/* This is an obsolete node belonging to the same directory, and it's of the right
+			   length. We need to take a closer look...*/
+			ret = jffs2_flash_read(c, ref_offset(raw), rawlen, &retlen, (char *)rd);
+			if (ret) {
+				pr_warn("%s(): Read error (%d) reading obsolete node at %08x\n",
+					__func__, ret, ref_offset(raw));
+				/* If we can't read it, we don't need to continue to obsolete it. Continue */
+				continue;
+			}
+			if (retlen != rawlen) {
+				pr_warn("%s(): Short read (%zd not %u) reading header from obsolete node at %08x\n",
+					__func__, retlen, rawlen,
+					ref_offset(raw));
+				continue;
+			}
+
+			if (je16_to_cpu(rd->nodetype) != JFFS2_NODETYPE_DIRENT)
+				continue;
+
+			/* If the name CRC doesn't match, skip */
+			if (je32_to_cpu(rd->name_crc) != name_crc)
+				continue;
+
+			/* If the name length doesn't match, or it's another deletion dirent, skip */
+			if (rd->nsize != name_len || !je32_to_cpu(rd->ino))
+				continue;
+
+			/* OK, check the actual name now */
+			if (memcmp(rd->name, fd->name, name_len))
+				continue;
+
+			/* OK. The name really does match. There really is still an older node on
+			   the flash which our deletion dirent obsoletes. So we have to write out
+			   a new deletion dirent to replace it */
+			mutex_unlock(&c->erase_free_sem);
+
+			jffs2_dbg(1, "Deletion dirent at %08x still obsoletes real dirent \"%s\" at %08x for ino #%u\n",
+				  ref_offset(fd->raw), fd->name,
+				  ref_offset(raw), je32_to_cpu(rd->ino));
+			kfree(rd);
+
+			return jffs2_garbage_collect_dirent(c, jeb, f, fd);
+		}
+
+		mutex_unlock(&c->erase_free_sem);
+		kfree(rd);
+	}
+
+	/* FIXME: If we're deleting a dirent which contains the current mtime and ctime,
+	   we should update the metadata node with those times accordingly */
+
+	/* No need for it any more. Just mark it obsolete and remove it from the list */
+	while (*fdp) {
+		if ((*fdp) == fd) {
+			found = 1;
+			*fdp = fd->next;
+			break;
+		}
+		fdp = &(*fdp)->next;
+	}
+	if (!found) {
+		pr_warn("Deletion dirent \"%s\" not found in list for ino #%u\n",
+			fd->name, f->inocache->ino);
+	}
+	jffs2_mark_node_obsolete(c, fd->raw);
+	jffs2_free_full_dirent(fd);
+	return 0;
+}
+
+static int jffs2_garbage_collect_hole(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
+				      struct jffs2_inode_info *f, struct jffs2_full_dnode *fn,
+				      uint32_t start, uint32_t end)
+{
+	struct jffs2_raw_inode ri;
+	struct jffs2_node_frag *frag;
+	struct jffs2_full_dnode *new_fn;
+	uint32_t alloclen, ilen;
+	int ret;
+
+	jffs2_dbg(1, "Writing replacement hole node for ino #%u from offset 0x%x to 0x%x\n",
+		  f->inocache->ino, start, end);
+
+	memset(&ri, 0, sizeof(ri));
+
+	if(fn->frags > 1) {
+		size_t readlen;
+		uint32_t crc;
+		/* It's partially obsoleted by a later write. So we have to
+		   write it out again with the _same_ version as before */
+		ret = jffs2_flash_read(c, ref_offset(fn->raw), sizeof(ri), &readlen, (char *)&ri);
+		if (readlen != sizeof(ri) || ret) {
+			pr_warn("Node read failed in jffs2_garbage_collect_hole. Ret %d, retlen %zd. Data will be lost by writing new hole node\n",
+				ret, readlen);
+			goto fill;
+		}
+		if (je16_to_cpu(ri.nodetype) != JFFS2_NODETYPE_INODE) {
+			pr_warn("%s(): Node at 0x%08x had node type 0x%04x instead of JFFS2_NODETYPE_INODE(0x%04x)\n",
+				__func__, ref_offset(fn->raw),
+				je16_to_cpu(ri.nodetype), JFFS2_NODETYPE_INODE);
+			return -EIO;
+		}
+		if (je32_to_cpu(ri.totlen) != sizeof(ri)) {
+			pr_warn("%s(): Node at 0x%08x had totlen 0x%x instead of expected 0x%zx\n",
+				__func__, ref_offset(fn->raw),
+				je32_to_cpu(ri.totlen), sizeof(ri));
+			return -EIO;
+		}
+		crc = crc32(0, &ri, sizeof(ri)-8);
+		if (crc != je32_to_cpu(ri.node_crc)) {
+			pr_warn("%s: Node at 0x%08x had CRC 0x%08x which doesn't match calculated CRC 0x%08x\n",
+				__func__, ref_offset(fn->raw),
+				je32_to_cpu(ri.node_crc), crc);
+			/* FIXME: We could possibly deal with this by writing new holes for each frag */
+			pr_warn("Data in the range 0x%08x to 0x%08x of inode #%u will be lost\n",
+				start, end, f->inocache->ino);
+			goto fill;
+		}
+		if (ri.compr != JFFS2_COMPR_ZERO) {
+			pr_warn("%s(): Node 0x%08x wasn't a hole node!\n",
+				__func__, ref_offset(fn->raw));
+			pr_warn("Data in the range 0x%08x to 0x%08x of inode #%u will be lost\n",
+				start, end, f->inocache->ino);
+			goto fill;
+		}
+	} else {
+	fill:
+		ri.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
+		ri.nodetype = cpu_to_je16(JFFS2_NODETYPE_INODE);
+		ri.totlen = cpu_to_je32(sizeof(ri));
+		ri.hdr_crc = cpu_to_je32(crc32(0, &ri, sizeof(struct jffs2_unknown_node)-4));
+
+		ri.ino = cpu_to_je32(f->inocache->ino);
+		ri.version = cpu_to_je32(++f->highest_version);
+		ri.offset = cpu_to_je32(start);
+		ri.dsize = cpu_to_je32(end - start);
+		ri.csize = cpu_to_je32(0);
+		ri.compr = JFFS2_COMPR_ZERO;
+	}
+
+	frag = frag_last(&f->fragtree);
+	if (frag)
+		/* Fetch the inode length from the fragtree rather then
+		 * from i_size since i_size may have not been updated yet */
+		ilen = frag->ofs + frag->size;
+	else
+		ilen = JFFS2_F_I_SIZE(f);
+
+	ri.mode = cpu_to_jemode(JFFS2_F_I_MODE(f));
+	ri.uid = cpu_to_je16(JFFS2_F_I_UID(f));
+	ri.gid = cpu_to_je16(JFFS2_F_I_GID(f));
+	ri.isize = cpu_to_je32(ilen);
+	ri.atime = cpu_to_je32(JFFS2_F_I_ATIME(f));
+	ri.ctime = cpu_to_je32(JFFS2_F_I_CTIME(f));
+	ri.mtime = cpu_to_je32(JFFS2_F_I_MTIME(f));
+	ri.data_crc = cpu_to_je32(0);
+	ri.node_crc = cpu_to_je32(crc32(0, &ri, sizeof(ri)-8));
+
+	ret = jffs2_reserve_space_gc(c, sizeof(ri), &alloclen,
+				     JFFS2_SUMMARY_INODE_SIZE);
+	if (ret) {
+		pr_warn("jffs2_reserve_space_gc of %zd bytes for garbage_collect_hole failed: %d\n",
+			sizeof(ri), ret);
+		return ret;
+	}
+	new_fn = jffs2_write_dnode(c, f, &ri, NULL, 0, ALLOC_GC);
+
+	if (IS_ERR(new_fn)) {
+		pr_warn("Error writing new hole node: %ld\n", PTR_ERR(new_fn));
+		return PTR_ERR(new_fn);
+	}
+	if (je32_to_cpu(ri.version) == f->highest_version) {
+		jffs2_add_full_dnode_to_inode(c, f, new_fn);
+		if (f->metadata) {
+			jffs2_mark_node_obsolete(c, f->metadata->raw);
+			jffs2_free_full_dnode(f->metadata);
+			f->metadata = NULL;
+		}
+		return 0;
+	}
+
+	/*
+	 * We should only get here in the case where the node we are
+	 * replacing had more than one frag, so we kept the same version
+	 * number as before. (Except in case of error -- see 'goto fill;'
+	 * above.)
+	 */
+	D1(if(unlikely(fn->frags <= 1)) {
+			pr_warn("%s(): Replacing fn with %d frag(s) but new ver %d != highest_version %d of ino #%d\n",
+				__func__, fn->frags, je32_to_cpu(ri.version),
+				f->highest_version, je32_to_cpu(ri.ino));
+	});
+
+	/* This is a partially-overlapped hole node. Mark it REF_NORMAL not REF_PRISTINE */
+	mark_ref_normal(new_fn->raw);
+
+	for (frag = jffs2_lookup_node_frag(&f->fragtree, fn->ofs);
+	     frag; frag = frag_next(frag)) {
+		if (frag->ofs > fn->size + fn->ofs)
+			break;
+		if (frag->node == fn) {
+			frag->node = new_fn;
+			new_fn->frags++;
+			fn->frags--;
+		}
+	}
+	if (fn->frags) {
+		pr_warn("%s(): Old node still has frags!\n", __func__);
+		BUG();
+	}
+	if (!new_fn->frags) {
+		pr_warn("%s(): New node has no frags!\n", __func__);
+		BUG();
+	}
+
+	jffs2_mark_node_obsolete(c, fn->raw);
+	jffs2_free_full_dnode(fn);
+
+	return 0;
+}
+
+static int jffs2_garbage_collect_dnode(struct jffs2_sb_info *c, struct jffs2_eraseblock *orig_jeb,
+				       struct jffs2_inode_info *f, struct jffs2_full_dnode *fn,
+				       uint32_t start, uint32_t end)
+{
+	struct inode *inode = OFNI_EDONI_2SFFJ(f);
+	struct jffs2_full_dnode *new_fn;
+	struct jffs2_raw_inode ri;
+	uint32_t alloclen, offset, orig_end, orig_start;
+	int ret = 0;
+	unsigned char *comprbuf = NULL, *writebuf;
+	struct page *page;
+	unsigned char *pg_ptr;
+
+	memset(&ri, 0, sizeof(ri));
+
+	jffs2_dbg(1, "Writing replacement dnode for ino #%u from offset 0x%x to 0x%x\n",
+		  f->inocache->ino, start, end);
+
+	orig_end = end;
+	orig_start = start;
+
+	if (c->nr_free_blocks + c->nr_erasing_blocks > c->resv_blocks_gcmerge) {
+		/* Attempt to do some merging. But only expand to cover logically
+		   adjacent frags if the block containing them is already considered
+		   to be dirty. Otherwise we end up with GC just going round in
+		   circles dirtying the nodes it already wrote out, especially
+		   on NAND where we have small eraseblocks and hence a much higher
+		   chance of nodes having to be split to cross boundaries. */
+
+		struct jffs2_node_frag *frag;
+		uint32_t min, max;
+
+		min = start & ~(PAGE_SIZE-1);
+		max = min + PAGE_SIZE;
+
+		frag = jffs2_lookup_node_frag(&f->fragtree, start);
+
+		/* BUG_ON(!frag) but that'll happen anyway... */
+
+		BUG_ON(frag->ofs != start);
+
+		/* First grow down... */
+		while((frag = frag_prev(frag)) && frag->ofs >= min) {
+
+			/* If the previous frag doesn't even reach the beginning, there's
+			   excessive fragmentation. Just merge. */
+			if (frag->ofs > min) {
+				jffs2_dbg(1, "Expanding down to cover partial frag (0x%x-0x%x)\n",
+					  frag->ofs, frag->ofs+frag->size);
+				start = frag->ofs;
+				continue;
+			}
+			/* OK. This frag holds the first byte of the page. */
+			if (!frag->node || !frag->node->raw) {
+				jffs2_dbg(1, "First frag in page is hole (0x%x-0x%x). Not expanding down.\n",
+					  frag->ofs, frag->ofs+frag->size);
+				break;
+			} else {
+
+				/* OK, it's a frag which extends to the beginning of the page. Does it live
+				   in a block which is still considered clean? If so, don't obsolete it.
+				   If not, cover it anyway. */
+
+				struct jffs2_raw_node_ref *raw = frag->node->raw;
+				struct jffs2_eraseblock *jeb;
+
+				jeb = &c->blocks[raw->flash_offset / c->sector_size];
+
+				if (jeb == c->gcblock) {
+					jffs2_dbg(1, "Expanding down to cover frag (0x%x-0x%x) in gcblock at %08x\n",
+						  frag->ofs,
+						  frag->ofs + frag->size,
+						  ref_offset(raw));
+					start = frag->ofs;
+					break;
+				}
+				if (!ISDIRTY(jeb->dirty_size + jeb->wasted_size)) {
+					jffs2_dbg(1, "Not expanding down to cover frag (0x%x-0x%x) in clean block %08x\n",
+						  frag->ofs,
+						  frag->ofs + frag->size,
+						  jeb->offset);
+					break;
+				}
+
+				jffs2_dbg(1, "Expanding down to cover frag (0x%x-0x%x) in dirty block %08x\n",
+					  frag->ofs,
+					  frag->ofs + frag->size,
+					  jeb->offset);
+				start = frag->ofs;
+				break;
+			}
+		}
+
+		/* ... then up */
+
+		/* Find last frag which is actually part of the node we're to GC. */
+		frag = jffs2_lookup_node_frag(&f->fragtree, end-1);
+
+		while((frag = frag_next(frag)) && frag->ofs+frag->size <= max) {
+
+			/* If the previous frag doesn't even reach the beginning, there's lots
+			   of fragmentation. Just merge. */
+			if (frag->ofs+frag->size < max) {
+				jffs2_dbg(1, "Expanding up to cover partial frag (0x%x-0x%x)\n",
+					  frag->ofs, frag->ofs+frag->size);
+				end = frag->ofs + frag->size;
+				continue;
+			}
+
+			if (!frag->node || !frag->node->raw) {
+				jffs2_dbg(1, "Last frag in page is hole (0x%x-0x%x). Not expanding up.\n",
+					  frag->ofs, frag->ofs+frag->size);
+				break;
+			} else {
+
+				/* OK, it's a frag which extends to the beginning of the page. Does it live
+				   in a block which is still considered clean? If so, don't obsolete it.
+				   If not, cover it anyway. */
+
+				struct jffs2_raw_node_ref *raw = frag->node->raw;
+				struct jffs2_eraseblock *jeb;
+
+				jeb = &c->blocks[raw->flash_offset / c->sector_size];
+
+				if (jeb == c->gcblock) {
+					jffs2_dbg(1, "Expanding up to cover frag (0x%x-0x%x) in gcblock at %08x\n",
+						  frag->ofs,
+						  frag->ofs + frag->size,
+						  ref_offset(raw));
+					end = frag->ofs + frag->size;
+					break;
+				}
+				if (!ISDIRTY(jeb->dirty_size + jeb->wasted_size)) {
+					jffs2_dbg(1, "Not expanding up to cover frag (0x%x-0x%x) in clean block %08x\n",
+						  frag->ofs,
+						  frag->ofs + frag->size,
+						  jeb->offset);
+					break;
+				}
+
+				jffs2_dbg(1, "Expanding up to cover frag (0x%x-0x%x) in dirty block %08x\n",
+					  frag->ofs,
+					  frag->ofs + frag->size,
+					  jeb->offset);
+				end = frag->ofs + frag->size;
+				break;
+			}
+		}
+		jffs2_dbg(1, "Expanded dnode to write from (0x%x-0x%x) to (0x%x-0x%x)\n",
+			  orig_start, orig_end, start, end);
+
+		D1(BUG_ON(end > frag_last(&f->fragtree)->ofs + frag_last(&f->fragtree)->size));
+		BUG_ON(end < orig_end);
+		BUG_ON(start > orig_start);
+	}
+
+	/* The rules state that we must obtain the page lock *before* f->sem, so
+	 * drop f->sem temporarily. Since we also hold c->alloc_sem, nothing's
+	 * actually going to *change* so we're safe; we only allow reading.
+	 *
+	 * It is important to note that jffs2_write_begin() will ensure that its
+	 * page is marked Uptodate before allocating space. That means that if we
+	 * end up here trying to GC the *same* page that jffs2_write_begin() is
+	 * trying to write out, read_cache_page() will not deadlock. */
+	mutex_unlock(&f->sem);
+	page = read_cache_page(inode->i_mapping, start >> PAGE_SHIFT,
+			       __jffs2_read_folio, NULL);
+	if (IS_ERR(page)) {
+		pr_warn("read_cache_page() returned error: %ld\n",
+			PTR_ERR(page));
+		mutex_lock(&f->sem);
+		return PTR_ERR(page);
+	}
+
+	pg_ptr = kmap(page);
+	mutex_lock(&f->sem);
+
+	offset = start;
+	while(offset < orig_end) {
+		uint32_t datalen;
+		uint32_t cdatalen;
+		uint16_t comprtype = JFFS2_COMPR_NONE;
+
+		ret = jffs2_reserve_space_gc(c, sizeof(ri) + JFFS2_MIN_DATA_LEN,
+					&alloclen, JFFS2_SUMMARY_INODE_SIZE);
+
+		if (ret) {
+			pr_warn("jffs2_reserve_space_gc of %zd bytes for garbage_collect_dnode failed: %d\n",
+				sizeof(ri) + JFFS2_MIN_DATA_LEN, ret);
+			break;
+		}
+		cdatalen = min_t(uint32_t, alloclen - sizeof(ri), end - offset);
+		datalen = end - offset;
+
+		writebuf = pg_ptr + (offset & (PAGE_SIZE -1));
+
+		comprtype = jffs2_compress(c, f, writebuf, &comprbuf, &datalen, &cdatalen);
+
+		ri.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
+		ri.nodetype = cpu_to_je16(JFFS2_NODETYPE_INODE);
+		ri.totlen = cpu_to_je32(sizeof(ri) + cdatalen);
+		ri.hdr_crc = cpu_to_je32(crc32(0, &ri, sizeof(struct jffs2_unknown_node)-4));
+
+		ri.ino = cpu_to_je32(f->inocache->ino);
+		ri.version = cpu_to_je32(++f->highest_version);
+		ri.mode = cpu_to_jemode(JFFS2_F_I_MODE(f));
+		ri.uid = cpu_to_je16(JFFS2_F_I_UID(f));
+		ri.gid = cpu_to_je16(JFFS2_F_I_GID(f));
+		ri.isize = cpu_to_je32(JFFS2_F_I_SIZE(f));
+		ri.atime = cpu_to_je32(JFFS2_F_I_ATIME(f));
+		ri.ctime = cpu_to_je32(JFFS2_F_I_CTIME(f));
+		ri.mtime = cpu_to_je32(JFFS2_F_I_MTIME(f));
+		ri.offset = cpu_to_je32(offset);
+		ri.csize = cpu_to_je32(cdatalen);
+		ri.dsize = cpu_to_je32(datalen);
+		ri.compr = comprtype & 0xff;
+		ri.usercompr = (comprtype >> 8) & 0xff;
+		ri.node_crc = cpu_to_je32(crc32(0, &ri, sizeof(ri)-8));
+		ri.data_crc = cpu_to_je32(crc32(0, comprbuf, cdatalen));
+
+		new_fn = jffs2_write_dnode(c, f, &ri, comprbuf, cdatalen, ALLOC_GC);
+
+		jffs2_free_comprbuf(comprbuf, writebuf);
+
+		if (IS_ERR(new_fn)) {
+			pr_warn("Error writing new dnode: %ld\n",
+				PTR_ERR(new_fn));
+			ret = PTR_ERR(new_fn);
+			break;
+		}
+		ret = jffs2_add_full_dnode_to_inode(c, f, new_fn);
+		offset += datalen;
+		if (f->metadata) {
+			jffs2_mark_node_obsolete(c, f->metadata->raw);
+			jffs2_free_full_dnode(f->metadata);
+			f->metadata = NULL;
+		}
+	}
+
+	kunmap(page);
+	put_page(page);
+	return ret;
+}