ext4: Remove old legacy block allocator

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

12 files changed, 40 insertions, 1528 deletions

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index cca7fd53ad7b..59566c082f1b 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -83,6 +83,7 @@ static int ext4_group_used_meta_blocks(struct super_block *sb,
 	}
 	return used_blocks;
 }
+
 /* Initializes an uninitialized block bitmap if given, and returns the
  * number of blocks free in the group. */
 unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
@@ -345,303 +346,6 @@ ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
 	 */
 	return bh;
 }
-/*
- * The reservation window structure operations
- * --------------------------------------------
- * Operations include:
- * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
- *
- * We use a red-black tree to represent per-filesystem reservation
- * windows.
- *
- */
-
-/**
- * __rsv_window_dump() -- Dump the filesystem block allocation reservation map
- * @rb_root:		root of per-filesystem reservation rb tree
- * @verbose:		verbose mode
- * @fn:			function which wishes to dump the reservation map
- *
- * If verbose is turned on, it will print the whole block reservation
- * windows(start, end).	Otherwise, it will only print out the "bad" windows,
- * those windows that overlap with their immediate neighbors.
- */
-#if 1
-static void __rsv_window_dump(struct rb_root *root, int verbose,
-			      const char *fn)
-{
-	struct rb_node *n;
-	struct ext4_reserve_window_node *rsv, *prev;
-	int bad;
-
-restart:
-	n = rb_first(root);
-	bad = 0;
-	prev = NULL;
-
-	printk(KERN_DEBUG "Block Allocation Reservation "
-	       "Windows Map (%s):\n", fn);
-	while (n) {
-		rsv = rb_entry(n, struct ext4_reserve_window_node, rsv_node);
-		if (verbose)
-			printk(KERN_DEBUG "reservation window 0x%p "
-			       "start:  %llu, end:  %llu\n",
-			       rsv, rsv->rsv_start, rsv->rsv_end);
-		if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
-			printk(KERN_DEBUG "Bad reservation %p (start >= end)\n",
-			       rsv);
-			bad = 1;
-		}
-		if (prev && prev->rsv_end >= rsv->rsv_start) {
-			printk(KERN_DEBUG "Bad reservation %p "
-			       "(prev->end >= start)\n", rsv);
-			bad = 1;
-		}
-		if (bad) {
-			if (!verbose) {
-				printk(KERN_DEBUG "Restarting reservation "
-				       "walk in verbose mode\n");
-				verbose = 1;
-				goto restart;
-			}
-		}
-		n = rb_next(n);
-		prev = rsv;
-	}
-	printk(KERN_DEBUG "Window map complete.\n");
-	BUG_ON(bad);
-}
-#define rsv_window_dump(root, verbose) \
-	__rsv_window_dump((root), (verbose), __func__)
-#else
-#define rsv_window_dump(root, verbose) do {} while (0)
-#endif
-
-/**
- * goal_in_my_reservation()
- * @rsv:		inode's reservation window
- * @grp_goal:		given goal block relative to the allocation block group
- * @group:		the current allocation block group
- * @sb:			filesystem super block
- *
- * Test if the given goal block (group relative) is within the file's
- * own block reservation window range.
- *
- * If the reservation window is outside the goal allocation group, return 0;
- * grp_goal (given goal block) could be -1, which means no specific
- * goal block. In this case, always return 1.
- * If the goal block is within the reservation window, return 1;
- * otherwise, return 0;
- */
-static int
-goal_in_my_reservation(struct ext4_reserve_window *rsv, ext4_grpblk_t grp_goal,
-			ext4_group_t group, struct super_block *sb)
-{
-	ext4_fsblk_t group_first_block, group_last_block;
-
-	group_first_block = ext4_group_first_block_no(sb, group);
-	group_last_block = group_first_block + (EXT4_BLOCKS_PER_GROUP(sb) - 1);
-
-	if ((rsv->_rsv_start > group_last_block) ||
-	    (rsv->_rsv_end < group_first_block))
-		return 0;
-	if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
-		|| (grp_goal + group_first_block > rsv->_rsv_end)))
-		return 0;
-	return 1;
-}
-
-/**
- * search_reserve_window()
- * @rb_root:		root of reservation tree
- * @goal:		target allocation block
- *
- * Find the reserved window which includes the goal, or the previous one
- * if the goal is not in any window.
- * Returns NULL if there are no windows or if all windows start after the goal.
- */
-static struct ext4_reserve_window_node *
-search_reserve_window(struct rb_root *root, ext4_fsblk_t goal)
-{
-	struct rb_node *n = root->rb_node;
-	struct ext4_reserve_window_node *rsv;
-
-	if (!n)
-		return NULL;
-
-	do {
-		rsv = rb_entry(n, struct ext4_reserve_window_node, rsv_node);
-
-		if (goal < rsv->rsv_start)
-			n = n->rb_left;
-		else if (goal > rsv->rsv_end)
-			n = n->rb_right;
-		else
-			return rsv;
-	} while (n);
-	/*
-	 * We've fallen off the end of the tree: the goal wasn't inside
-	 * any particular node.  OK, the previous node must be to one
-	 * side of the interval containing the goal.  If it's the RHS,
-	 * we need to back up one.
-	 */
-	if (rsv->rsv_start > goal) {
-		n = rb_prev(&rsv->rsv_node);
-		rsv = rb_entry(n, struct ext4_reserve_window_node, rsv_node);
-	}
-	return rsv;
-}
-
-/**
- * ext4_rsv_window_add() -- Insert a window to the block reservation rb tree.
- * @sb:			super block
- * @rsv:		reservation window to add
- *
- * Must be called with rsv_lock hold.
- */
-void ext4_rsv_window_add(struct super_block *sb,
-		    struct ext4_reserve_window_node *rsv)
-{
-	struct rb_root *root = &EXT4_SB(sb)->s_rsv_window_root;
-	struct rb_node *node = &rsv->rsv_node;
-	ext4_fsblk_t start = rsv->rsv_start;
-
-	struct rb_node **p = &root->rb_node;
-	struct rb_node *parent = NULL;
-	struct ext4_reserve_window_node *this;
-
-	while (*p)
-	{
-		parent = *p;
-		this = rb_entry(parent, struct ext4_reserve_window_node, rsv_node);
-
-		if (start < this->rsv_start)
-			p = &(*p)->rb_left;
-		else if (start > this->rsv_end)
-			p = &(*p)->rb_right;
-		else {
-			rsv_window_dump(root, 1);
-			BUG();
-		}
-	}
-
-	rb_link_node(node, parent, p);
-	rb_insert_color(node, root);
-}
-
-/**
- * ext4_rsv_window_remove() -- unlink a window from the reservation rb tree
- * @sb:			super block
- * @rsv:		reservation window to remove
- *
- * Mark the block reservation window as not allocated, and unlink it
- * from the filesystem reservation window rb tree. Must be called with
- * rsv_lock hold.
- */
-static void rsv_window_remove(struct super_block *sb,
-			      struct ext4_reserve_window_node *rsv)
-{
-	rsv->rsv_start = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
-	rsv->rsv_end = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
-	rsv->rsv_alloc_hit = 0;
-	rb_erase(&rsv->rsv_node, &EXT4_SB(sb)->s_rsv_window_root);
-}
-
-/*
- * rsv_is_empty() -- Check if the reservation window is allocated.
- * @rsv:		given reservation window to check
- *
- * returns 1 if the end block is EXT4_RESERVE_WINDOW_NOT_ALLOCATED.
- */
-static inline int rsv_is_empty(struct ext4_reserve_window *rsv)
-{
-	/* a valid reservation end block could not be 0 */
-	return rsv->_rsv_end == EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
-}
-
-/**
- * ext4_init_block_alloc_info()
- * @inode:		file inode structure
- *
- * Allocate and initialize the	reservation window structure, and
- * link the window to the ext4 inode structure at last
- *
- * The reservation window structure is only dynamically allocated
- * and linked to ext4 inode the first time the open file
- * needs a new block. So, before every ext4_new_block(s) call, for
- * regular files, we should check whether the reservation window
- * structure exists or not. In the latter case, this function is called.
- * Fail to do so will result in block reservation being turned off for that
- * open file.
- *
- * This function is called from ext4_get_blocks_handle(), also called
- * when setting the reservation window size through ioctl before the file
- * is open for write (needs block allocation).
- *
- * Needs down_write(i_data_sem) protection prior to call this function.
- */
-void ext4_init_block_alloc_info(struct inode *inode)
-{
-	struct ext4_inode_info *ei = EXT4_I(inode);
-	struct ext4_block_alloc_info *block_i = ei->i_block_alloc_info;
-	struct super_block *sb = inode->i_sb;
-
-	block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
-	if (block_i) {
-		struct ext4_reserve_window_node *rsv = &block_i->rsv_window_node;
-
-		rsv->rsv_start = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
-		rsv->rsv_end = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
-
-		/*
-		 * if filesystem is mounted with NORESERVATION, the goal
-		 * reservation window size is set to zero to indicate
-		 * block reservation is off
-		 */
-		if (!test_opt(sb, RESERVATION))
-			rsv->rsv_goal_size = 0;
-		else
-			rsv->rsv_goal_size = EXT4_DEFAULT_RESERVE_BLOCKS;
-		rsv->rsv_alloc_hit = 0;
-		block_i->last_alloc_logical_block = 0;
-		block_i->last_alloc_physical_block = 0;
-	}
-	ei->i_block_alloc_info = block_i;
-}
-
-/**
- * ext4_discard_reservation()
- * @inode:		inode
- *
- * Discard(free) block reservation window on last file close, or truncate
- * or at last iput().
- *
- * It is being called in three cases:
- *	ext4_release_file(): last writer close the file
- *	ext4_clear_inode(): last iput(), when nobody link to this file.
- *	ext4_truncate(): when the block indirect map is about to change.
- *
- */
-void ext4_discard_reservation(struct inode *inode)
-{
-	struct ext4_inode_info *ei = EXT4_I(inode);
-	struct ext4_block_alloc_info *block_i = ei->i_block_alloc_info;
-	struct ext4_reserve_window_node *rsv;
-	spinlock_t *rsv_lock = &EXT4_SB(inode->i_sb)->s_rsv_window_lock;
-
-	ext4_mb_discard_inode_preallocations(inode);
-
-	if (!block_i)
-		return;
-
-	rsv = &block_i->rsv_window_node;
-	if (!rsv_is_empty(&rsv->rsv_window)) {
-		spin_lock(rsv_lock);
-		if (!rsv_is_empty(&rsv->rsv_window))
-			rsv_window_remove(inode->i_sb, rsv);
-		spin_unlock(rsv_lock);
-	}
-}
 
 /**
  * ext4_free_blocks_sb() -- Free given blocks and update quota
@@ -650,6 +354,13 @@ void ext4_discard_reservation(struct inode *inode)
  * @block:			start physcial block to free
  * @count:			number of blocks to free
  * @pdquot_freed_blocks:	pointer to quota
+ *
+ * XXX This function is only used by the on-line resizing code, which
+ * should probably be fixed up to call the mballoc variant.  There
+ * this needs to be cleaned up later; in fact, I'm not convinced this
+ * is 100% correct in the face of the mballoc code.  The online resizing
+ * code needs to be fixed up to more tightly (and correctly) interlock
+ * with the mballoc code.
  */
 void ext4_free_blocks_sb(handle_t *handle, struct super_block *sb,
 			 ext4_fsblk_t block, unsigned long count,
@@ -861,747 +572,13 @@ void ext4_free_blocks(handle_t *handle, struct inode *inode,
 
 	sb = inode->i_sb;
 
-	if (!test_opt(sb, MBALLOC) || !EXT4_SB(sb)->s_group_info)
-		ext4_free_blocks_sb(handle, sb, block, count,
-						&dquot_freed_blocks);
-	else
-		ext4_mb_free_blocks(handle, inode, block, count,
-						metadata, &dquot_freed_blocks);
+	ext4_mb_free_blocks(handle, inode, block, count,
+			    metadata, &dquot_freed_blocks);
 	if (dquot_freed_blocks)
 		DQUOT_FREE_BLOCK(inode, dquot_freed_blocks);
 	return;
 }
 
-/**
- * ext4_test_allocatable()
- * @nr:			given allocation block group
- * @bh:			bufferhead contains the bitmap of the given block group
- *
- * For ext4 allocations, we must not reuse any blocks which are
- * allocated in the bitmap buffer's "last committed data" copy.  This
- * prevents deletes from freeing up the page for reuse until we have
- * committed the delete transaction.
- *
- * If we didn't do this, then deleting something and reallocating it as
- * data would allow the old block to be overwritten before the
- * transaction committed (because we force data to disk before commit).
- * This would lead to corruption if we crashed between overwriting the
- * data and committing the delete.
- *
- * @@@ We may want to make this allocation behaviour conditional on
- * data-writes at some point, and disable it for metadata allocations or
- * sync-data inodes.
- */
-static int ext4_test_allocatable(ext4_grpblk_t nr, struct buffer_head *bh)
-{
-	int ret;
-	struct journal_head *jh = bh2jh(bh);
-
-	if (ext4_test_bit(nr, bh->b_data))
-		return 0;
-
-	jbd_lock_bh_state(bh);
-	if (!jh->b_committed_data)
-		ret = 1;
-	else
-		ret = !ext4_test_bit(nr, jh->b_committed_data);
-	jbd_unlock_bh_state(bh);
-	return ret;
-}
-
-/**
- * bitmap_search_next_usable_block()
- * @start:		the starting block (group relative) of the search
- * @bh:			bufferhead contains the block group bitmap
- * @maxblocks:		the ending block (group relative) of the reservation
- *
- * The bitmap search --- search forward alternately through the actual
- * bitmap on disk and the last-committed copy in journal, until we find a
- * bit free in both bitmaps.
- */
-static ext4_grpblk_t
-bitmap_search_next_usable_block(ext4_grpblk_t start, struct buffer_head *bh,
-					ext4_grpblk_t maxblocks)
-{
-	ext4_grpblk_t next;
-	struct journal_head *jh = bh2jh(bh);
-
-	while (start < maxblocks) {
-		next = ext4_find_next_zero_bit(bh->b_data, maxblocks, start);
-		if (next >= maxblocks)
-			return -1;
-		if (ext4_test_allocatable(next, bh))
-			return next;
-		jbd_lock_bh_state(bh);
-		if (jh->b_committed_data)
-			start = ext4_find_next_zero_bit(jh->b_committed_data,
-							maxblocks, next);
-		jbd_unlock_bh_state(bh);
-	}
-	return -1;
-}
-
-/**
- * find_next_usable_block()
- * @start:		the starting block (group relative) to find next
- *			allocatable block in bitmap.
- * @bh:			bufferhead contains the block group bitmap
- * @maxblocks:		the ending block (group relative) for the search
- *
- * Find an allocatable block in a bitmap.  We honor both the bitmap and
- * its last-committed copy (if that exists), and perform the "most
- * appropriate allocation" algorithm of looking for a free block near
- * the initial goal; then for a free byte somewhere in the bitmap; then
- * for any free bit in the bitmap.
- */
-static ext4_grpblk_t
-find_next_usable_block(ext4_grpblk_t start, struct buffer_head *bh,
-			ext4_grpblk_t maxblocks)
-{
-	ext4_grpblk_t here, next;
-	char *p, *r;
-
-	if (start > 0) {
-		/*
-		 * The goal was occupied; search forward for a free
-		 * block within the next XX blocks.
-		 *
-		 * end_goal is more or less random, but it has to be
-		 * less than EXT4_BLOCKS_PER_GROUP. Aligning up to the
-		 * next 64-bit boundary is simple..
-		 */
-		ext4_grpblk_t end_goal = (start + 63) & ~63;
-		if (end_goal > maxblocks)
-			end_goal = maxblocks;
-		here = ext4_find_next_zero_bit(bh->b_data, end_goal, start);
-		if (here < end_goal && ext4_test_allocatable(here, bh))
-			return here;
-		ext4_debug("Bit not found near goal\n");
-	}
-
-	here = start;
-	if (here < 0)
-		here = 0;
-
-	p = ((char *)bh->b_data) + (here >> 3);
-	r = memscan(p, 0, ((maxblocks + 7) >> 3) - (here >> 3));
-	next = (r - ((char *)bh->b_data)) << 3;
-
-	if (next < maxblocks && next >= start && ext4_test_allocatable(next, bh))
-		return next;
-
-	/*
-	 * The bitmap search --- search forward alternately through the actual
-	 * bitmap and the last-committed copy until we find a bit free in
-	 * both
-	 */
-	here = bitmap_search_next_usable_block(here, bh, maxblocks);
-	return here;
-}
-
-/**
- * claim_block()
- * @block:		the free block (group relative) to allocate
- * @bh:			the bufferhead containts the block group bitmap
- *
- * We think we can allocate this block in this bitmap.  Try to set the bit.
- * If that succeeds then check that nobody has allocated and then freed the
- * block since we saw that is was not marked in b_committed_data.  If it _was_
- * allocated and freed then clear the bit in the bitmap again and return
- * zero (failure).
- */
-static inline int
-claim_block(spinlock_t *lock, ext4_grpblk_t block, struct buffer_head *bh)
-{
-	struct journal_head *jh = bh2jh(bh);
-	int ret;
-
-	if (ext4_set_bit_atomic(lock, block, bh->b_data))
-		return 0;
-	jbd_lock_bh_state(bh);
-	if (jh->b_committed_data && ext4_test_bit(block, jh->b_committed_data)) {
-		ext4_clear_bit_atomic(lock, block, bh->b_data);
-		ret = 0;
-	} else {
-		ret = 1;
-	}
-	jbd_unlock_bh_state(bh);
-	return ret;
-}
-
-/**
- * ext4_try_to_allocate()
- * @sb:			superblock
- * @handle:		handle to this transaction
- * @group:		given allocation block group
- * @bitmap_bh:		bufferhead holds the block bitmap
- * @grp_goal:		given target block within the group
- * @count:		target number of blocks to allocate
- * @my_rsv:		reservation window
- *
- * Attempt to allocate blocks within a give range. Set the range of allocation
- * first, then find the first free bit(s) from the bitmap (within the range),
- * and at last, allocate the blocks by claiming the found free bit as allocated.
- *
- * To set the range of this allocation:
- *	if there is a reservation window, only try to allocate block(s) from the
- *	file's own reservation window;
- *	Otherwise, the allocation range starts from the give goal block, ends at
- *	the block group's last block.
- *
- * If we failed to allocate the desired block then we may end up crossing to a
- * new bitmap.  In that case we must release write access to the old one via
- * ext4_journal_release_buffer(), else we'll run out of credits.
- */
-static ext4_grpblk_t
-ext4_try_to_allocate(struct super_block *sb, handle_t *handle,
-			ext4_group_t group, struct buffer_head *bitmap_bh,
-			ext4_grpblk_t grp_goal, unsigned long *count,
-			struct ext4_reserve_window *my_rsv)
-{
-	ext4_fsblk_t group_first_block;
-	ext4_grpblk_t start, end;
-	unsigned long num = 0;
-
-	/* we do allocation within the reservation window if we have a window */
-	if (my_rsv) {
-		group_first_block = ext4_group_first_block_no(sb, group);
-		if (my_rsv->_rsv_start >= group_first_block)
-			start = my_rsv->_rsv_start - group_first_block;
-		else
-			/* reservation window cross group boundary */
-			start = 0;
-		end = my_rsv->_rsv_end - group_first_block + 1;
-		if (end > EXT4_BLOCKS_PER_GROUP(sb))
-			/* reservation window crosses group boundary */
-			end = EXT4_BLOCKS_PER_GROUP(sb);
-		if ((start <= grp_goal) && (grp_goal < end))
-			start = grp_goal;
-		else
-			grp_goal = -1;
-	} else {
-		if (grp_goal > 0)
-			start = grp_goal;
-		else
-			start = 0;
-		end = EXT4_BLOCKS_PER_GROUP(sb);
-	}
-
-	BUG_ON(start > EXT4_BLOCKS_PER_GROUP(sb));
-
-repeat:
-	if (grp_goal < 0 || !ext4_test_allocatable(grp_goal, bitmap_bh)) {
-		grp_goal = find_next_usable_block(start, bitmap_bh, end);
-		if (grp_goal < 0)
-			goto fail_access;
-		if (!my_rsv) {
-			int i;
-
-			for (i = 0; i < 7 && grp_goal > start &&
-					ext4_test_allocatable(grp_goal - 1,
-								bitmap_bh);
-					i++, grp_goal--)
-				;
-		}
-	}
-	start = grp_goal;
-
-	if (!claim_block(sb_bgl_lock(EXT4_SB(sb), group),
-		grp_goal, bitmap_bh)) {
-		/*
-		 * The block was allocated by another thread, or it was
-		 * allocated and then freed by another thread
-		 */
-		start++;
-		grp_goal++;
-		if (start >= end)
-			goto fail_access;
-		goto repeat;
-	}
-	num++;
-	grp_goal++;
-	while (num < *count && grp_goal < end
-		&& ext4_test_allocatable(grp_goal, bitmap_bh)
-		&& claim_block(sb_bgl_lock(EXT4_SB(sb), group),
-				grp_goal, bitmap_bh)) {
-		num++;
-		grp_goal++;
-	}
-	*count = num;
-	return grp_goal - num;
-fail_access:
-	*count = num;
-	return -1;
-}
-
-/**
- *	find_next_reservable_window():
- *		find a reservable space within the given range.
- *		It does not allocate the reservation window for now:
- *		alloc_new_reservation() will do the work later.
- *
- *	@search_head: the head of the searching list;
- *		This is not necessarily the list head of the whole filesystem
- *
- *		We have both head and start_block to assist the search
- *		for the reservable space. The list starts from head,
- *		but we will shift to the place where start_block is,
- *		then start from there, when looking for a reservable space.
- *
- *	@size: the target new reservation window size
- *
- *	@group_first_block: the first block we consider to start
- *			the real search from
- *
- *	@last_block:
- *		the maximum block number that our goal reservable space
- *		could start from. This is normally the last block in this
- *		group. The search will end when we found the start of next
- *		possible reservable space is out of this boundary.
- *		This could handle the cross boundary reservation window
- *		request.
- *
- *	basically we search from the given range, rather than the whole
- *	reservation double linked list, (start_block, last_block)
- *	to find a free region that is of my size and has not
- *	been reserved.
- *
- */
-static int find_next_reservable_window(
-				struct ext4_reserve_window_node *search_head,
-				struct ext4_reserve_window_node *my_rsv,
-				struct super_block *sb,
-				ext4_fsblk_t start_block,
-				ext4_fsblk_t last_block)
-{
-	struct rb_node *next;
-	struct ext4_reserve_window_node *rsv, *prev;
-	ext4_fsblk_t cur;
-	int size = my_rsv->rsv_goal_size;
-
-	/* TODO: make the start of the reservation window byte-aligned */
-	/* cur = *start_block & ~7;*/
-	cur = start_block;
-	rsv = search_head;
-	if (!rsv)
-		return -1;
-
-	while (1) {
-		if (cur <= rsv->rsv_end)
-			cur = rsv->rsv_end + 1;
-
-		/* TODO?
-		 * in the case we could not find a reservable space
-		 * that is what is expected, during the re-search, we could
-		 * remember what's the largest reservable space we could have
-		 * and return that one.
-		 *
-		 * For now it will fail if we could not find the reservable
-		 * space with expected-size (or more)...
-		 */
-		if (cur > last_block)
-			return -1;		/* fail */
-
-		prev = rsv;
-		next = rb_next(&rsv->rsv_node);
-		rsv = rb_entry(next, struct ext4_reserve_window_node, rsv_node);
-
-		/*
-		 * Reached the last reservation, we can just append to the
-		 * previous one.
-		 */
-		if (!next)
-			break;
-
-		if (cur + size <= rsv->rsv_start) {
-			/*
-			 * Found a reserveable space big enough.  We could
-			 * have a reservation across the group boundary here
-			 */
-			break;
-		}
-	}
-	/*
-	 * we come here either :
-	 * when we reach the end of the whole list,
-	 * and there is empty reservable space after last entry in the list.
-	 * append it to the end of the list.
-	 *
-	 * or we found one reservable space in the middle of the list,
-	 * return the reservation window that we could append to.
-	 * succeed.
-	 */
-
-	if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
-		rsv_window_remove(sb, my_rsv);
-
-	/*
-	 * Let's book the whole avaliable window for now.  We will check the
-	 * disk bitmap later and then, if there are free blocks then we adjust
-	 * the window size if it's larger than requested.
-	 * Otherwise, we will remove this node from the tree next time
-	 * call find_next_reservable_window.
-	 */
-	my_rsv->rsv_start = cur;
-	my_rsv->rsv_end = cur + size - 1;
-	my_rsv->rsv_alloc_hit = 0;
-
-	if (prev != my_rsv)
-		ext4_rsv_window_add(sb, my_rsv);
-
-	return 0;
-}
-
-/**
- *	alloc_new_reservation()--allocate a new reservation window
- *
- *		To make a new reservation, we search part of the filesystem
- *		reservation list (the list that inside the group). We try to
- *		allocate a new reservation window near the allocation goal,
- *		or the beginning of the group, if there is no goal.
- *
- *		We first find a reservable space after the goal, then from
- *		there, we check the bitmap for the first free block after
- *		it. If there is no free block until the end of group, then the
- *		whole group is full, we failed. Otherwise, check if the free
- *		block is inside the expected reservable space, if so, we
- *		succeed.
- *		If the first free block is outside the reservable space, then
- *		start from the first free block, we search for next available
- *		space, and go on.
- *
- *	on succeed, a new reservation will be found and inserted into the list
- *	It contains at least one free block, and it does not overlap with other
- *	reservation windows.
- *
- *	failed: we failed to find a reservation window in this group
- *
- *	@rsv: the reservation
- *
- *	@grp_goal: The goal (group-relative).  It is where the search for a
- *		free reservable space should start from.
- *		if we have a grp_goal(grp_goal >0 ), then start from there,
- *		no grp_goal(grp_goal = -1), we start from the first block
- *		of the group.
- *
- *	@sb: the super block
- *	@group: the group we are trying to allocate in
- *	@bitmap_bh: the block group block bitmap
- *
- */
-static int alloc_new_reservation(struct ext4_reserve_window_node *my_rsv,
-		ext4_grpblk_t grp_goal, struct super_block *sb,
-		ext4_group_t group, struct buffer_head *bitmap_bh)
-{
-	struct ext4_reserve_window_node *search_head;
-	ext4_fsblk_t group_first_block, group_end_block, start_block;
-	ext4_grpblk_t first_free_block;
-	struct rb_root *fs_rsv_root = &EXT4_SB(sb)->s_rsv_window_root;
-	unsigned long size;
-	int ret;
-	spinlock_t *rsv_lock = &EXT4_SB(sb)->s_rsv_window_lock;
-
-	group_first_block = ext4_group_first_block_no(sb, group);
-	group_end_block = group_first_block + (EXT4_BLOCKS_PER_GROUP(sb) - 1);
-
-	if (grp_goal < 0)
-		start_block = group_first_block;
-	else
-		start_block = grp_goal + group_first_block;
-
-	size = my_rsv->rsv_goal_size;
-
-	if (!rsv_is_empty(&my_rsv->rsv_window)) {
-		/*
-		 * if the old reservation is cross group boundary
-		 * and if the goal is inside the old reservation window,
-		 * we will come here when we just failed to allocate from
-		 * the first part of the window. We still have another part
-		 * that belongs to the next group. In this case, there is no
-		 * point to discard our window and try to allocate a new one
-		 * in this group(which will fail). we should
-		 * keep the reservation window, just simply move on.
-		 *
-		 * Maybe we could shift the start block of the reservation
-		 * window to the first block of next group.
-		 */
-
-		if ((my_rsv->rsv_start <= group_end_block) &&
-				(my_rsv->rsv_end > group_end_block) &&
-				(start_block >= my_rsv->rsv_start))
-			return -1;
-
-		if ((my_rsv->rsv_alloc_hit >
-		     (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
-			/*
-			 * if the previously allocation hit ratio is
-			 * greater than 1/2, then we double the size of
-			 * the reservation window the next time,
-			 * otherwise we keep the same size window
-			 */
-			size = size * 2;
-			if (size > EXT4_MAX_RESERVE_BLOCKS)
-				size = EXT4_MAX_RESERVE_BLOCKS;
-			my_rsv->rsv_goal_size = size;
-		}
-	}
-
-	spin_lock(rsv_lock);
-	/*
-	 * shift the search start to the window near the goal block
-	 */
-	search_head = search_reserve_window(fs_rsv_root, start_block);
-
-	/*
-	 * find_next_reservable_window() simply finds a reservable window
-	 * inside the given range(start_block, group_end_block).
-	 *
-	 * To make sure the reservation window has a free bit inside it, we
-	 * need to check the bitmap after we found a reservable window.
-	 */
-retry:
-	ret = find_next_reservable_window(search_head, my_rsv, sb,
-						start_block, group_end_block);
-
-	if (ret == -1) {
-		if (!rsv_is_empty(&my_rsv->rsv_window))
-			rsv_window_remove(sb, my_rsv);
-		spin_unlock(rsv_lock);
-		return -1;
-	}
-
-	/*
-	 * On success, find_next_reservable_window() returns the
-	 * reservation window where there is a reservable space after it.
-	 * Before we reserve this reservable space, we need
-	 * to make sure there is at least a free block inside this region.
-	 *
-	 * searching the first free bit on the block bitmap and copy of
-	 * last committed bitmap alternatively, until we found a allocatable
-	 * block. Search start from the start block of the reservable space
-	 * we just found.
-	 */
-	spin_unlock(rsv_lock);
-	first_free_block = bitmap_search_next_usable_block(
-			my_rsv->rsv_start - group_first_block,
-			bitmap_bh, group_end_block - group_first_block + 1);
-
-	if (first_free_block < 0) {
-		/*
-		 * no free block left on the bitmap, no point
-		 * to reserve the space. return failed.
-		 */
-		spin_lock(rsv_lock);
-		if (!rsv_is_empty(&my_rsv->rsv_window))
-			rsv_window_remove(sb, my_rsv);
-		spin_unlock(rsv_lock);
-		return -1;		/* failed */
-	}
-
-	start_block = first_free_block + group_first_block;
-	/*
-	 * check if the first free block is within the
-	 * free space we just reserved
-	 */
-	if (start_block >= my_rsv->rsv_start && start_block <= my_rsv->rsv_end)
-		return 0;		/* success */
-	/*
-	 * if the first free bit we found is out of the reservable space
-	 * continue search for next reservable space,
-	 * start from where the free block is,
-	 * we also shift the list head to where we stopped last time
-	 */
-	search_head = my_rsv;
-	spin_lock(rsv_lock);
-	goto retry;
-}
-
-/**
- * try_to_extend_reservation()
- * @my_rsv:		given reservation window
- * @sb:			super block
- * @size:		the delta to extend
- *
- * Attempt to expand the reservation window large enough to have
- * required number of free blocks
- *
- * Since ext4_try_to_allocate() will always allocate blocks within
- * the reservation window range, if the window size is too small,
- * multiple blocks allocation has to stop at the end of the reservation
- * window. To make this more efficient, given the total number of
- * blocks needed and the current size of the window, we try to
- * expand the reservation window size if necessary on a best-effort
- * basis before ext4_new_blocks() tries to allocate blocks,
- */
-static void try_to_extend_reservation(struct ext4_reserve_window_node *my_rsv,
-			struct super_block *sb, int size)
-{
-	struct ext4_reserve_window_node *next_rsv;
-	struct rb_node *next;
-	spinlock_t *rsv_lock = &EXT4_SB(sb)->s_rsv_window_lock;
-
-	if (!spin_trylock(rsv_lock))
-		return;
-
-	next = rb_next(&my_rsv->rsv_node);
-
-	if (!next)
-		my_rsv->rsv_end += size;
-	else {
-		next_rsv = rb_entry(next, struct ext4_reserve_window_node, rsv_node);
-
-		if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
-			my_rsv->rsv_end += size;
-		else
-			my_rsv->rsv_end = next_rsv->rsv_start - 1;
-	}
-	spin_unlock(rsv_lock);
-}
-
-/**
- * ext4_try_to_allocate_with_rsv()
- * @sb:			superblock
- * @handle:		handle to this transaction
- * @group:		given allocation block group
- * @bitmap_bh:		bufferhead holds the block bitmap
- * @grp_goal:		given target block within the group
- * @count:		target number of blocks to allocate
- * @my_rsv:		reservation window
- * @errp:		pointer to store the error code
- *
- * This is the main function used to allocate a new block and its reservation
- * window.
- *
- * Each time when a new block allocation is need, first try to allocate from
- * its own reservation.  If it does not have a reservation window, instead of
- * looking for a free bit on bitmap first, then look up the reservation list to
- * see if it is inside somebody else's reservation window, we try to allocate a
- * reservation window for it starting from the goal first. Then do the block
- * allocation within the reservation window.
- *
- * This will avoid keeping on searching the reservation list again and
- * again when somebody is looking for a free block (without
- * reservation), and there are lots of free blocks, but they are all
- * being reserved.
- *
- * We use a red-black tree for the per-filesystem reservation list.
- *
- */
-static ext4_grpblk_t
-ext4_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle,
-			ext4_group_t group, struct buffer_head *bitmap_bh,
-			ext4_grpblk_t grp_goal,
-			struct ext4_reserve_window_node *my_rsv,
-			unsigned long *count, int *errp)
-{
-	ext4_fsblk_t group_first_block, group_last_block;
-	ext4_grpblk_t ret = 0;
-	int fatal;
-	unsigned long num = *count;
-
-	*errp = 0;
-
-	/*
-	 * Make sure we use undo access for the bitmap, because it is critical
-	 * that we do the frozen_data COW on bitmap buffers in all cases even
-	 * if the buffer is in BJ_Forget state in the committing transaction.
-	 */
-	BUFFER_TRACE(bitmap_bh, "get undo access for new block");
-	fatal = ext4_journal_get_undo_access(handle, bitmap_bh);
-	if (fatal) {
-		*errp = fatal;
-		return -1;
-	}
-
-	/*
-	 * we don't deal with reservation when
-	 * filesystem is mounted without reservation
-	 * or the file is not a regular file
-	 * or last attempt to allocate a block with reservation turned on failed
-	 */
-	if (my_rsv == NULL) {
-		ret = ext4_try_to_allocate(sb, handle, group, bitmap_bh,
-						grp_goal, count, NULL);
-		goto out;
-	}
-	/*