X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=fs%2Fext3%2Fballoc.c;h=75369a95cceece50065dafe602e2476c13a5782c;hb=8924cb29b44d7e7bc69a58f6d196470a5bcd9385;hp=893b08bd5c1798a2375382dbc787222bcc1f9126;hpb=86090fcac5e27b630656fe3d963a6b80e26dac44;p=linux-2.6.git

diff --git a/fs/ext3/balloc.c b/fs/ext3/balloc.c
index 893b08bd5..75369a95c 100644
--- a/fs/ext3/balloc.c
+++ b/fs/ext3/balloc.c
@@ -96,9 +96,87 @@ read_block_bitmap(struct super_block *sb, unsigned int block_group)
 error_out:
 	return bh;
 }
+/*
+ * The reservation window structure operations
+ * --------------------------------------------
+ * Operations include:
+ * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
+ *
+ * We use sorted double linked list for the per-filesystem reservation
+ * window list. (like in vm_region).
+ *
+ * Initially, we keep those small operations in the abstract functions,
+ * so later if we need a better searching tree than double linked-list,
+ * we could easily switch to that without changing too much
+ * code.
+ */
+static inline void rsv_window_dump(struct reserve_window *head, char *fn)
+{
+	struct reserve_window *rsv;
+
+	printk("Block Allocation Reservation Windows Map (%s):\n", fn);
+	list_for_each_entry(rsv, &head->rsv_list, rsv_list) {
+		printk("reservation window 0x%p start:  %d, end:  %d\n",
+			 rsv, rsv->rsv_start, rsv->rsv_end);
+	}
+}
+
+static int
+goal_in_my_reservation(struct reserve_window *rsv, int goal,
+			unsigned int group, struct super_block * sb)
+{
+	unsigned long group_first_block, group_last_block;
+
+	group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
+				group * EXT3_BLOCKS_PER_GROUP(sb);
+	group_last_block = group_first_block + EXT3_BLOCKS_PER_GROUP(sb) - 1;
+
+	if ((rsv->rsv_start > group_last_block) ||
+	    (rsv->rsv_end < group_first_block))
+		return 0;
+	if ((goal >= 0) && ((goal + group_first_block < rsv->rsv_start)
+		|| (goal + group_first_block > rsv->rsv_end)))
+		return 0;
+	return 1;
+}
+
+static inline void rsv_window_add(struct reserve_window *rsv,
+					struct reserve_window *prev)
+{
+	/* insert the new reservation window after the head */
+	list_add(&rsv->rsv_list, &prev->rsv_list);
+}
+
+static inline void rsv_window_remove(struct reserve_window *rsv)
+{
+	rsv->rsv_start = 0;
+	rsv->rsv_end = 0;
+		rsv->rsv_alloc_hit = 0;
+	list_del(&rsv->rsv_list);
+	INIT_LIST_HEAD(&rsv->rsv_list);
+}
+
+static inline int rsv_is_empty(struct reserve_window *rsv)
+{
+	/* a valid reservation end block could not be 0 */
+	return (rsv->rsv_end == 0);
+}
+
+void ext3_discard_reservation(struct inode *inode)
+{
+	struct ext3_inode_info *ei = EXT3_I(inode);
+	struct reserve_window *rsv = &ei->i_rsv_window;
+	spinlock_t *rsv_lock = &EXT3_SB(inode->i_sb)->s_rsv_window_lock;
+
+	if (!rsv_is_empty(rsv)) {
+		spin_lock(rsv_lock);
+		rsv_window_remove(rsv);
+		spin_unlock(rsv_lock);
+	}
+}
 
 /* Free given blocks, update quota and i_blocks field */
-void ext3_free_blocks (handle_t *handle, struct inode * inode,
+void ext3_free_blocks(handle_t *handle, struct inode *inode,
 			unsigned long block, unsigned long count)
 {
 	struct buffer_head *bitmap_bh = NULL;
@@ -275,7 +353,7 @@ do_more:
 error_return:
 	brelse(bitmap_bh);
 	ext3_std_error(sb, err);
-	if (dquot_freed_blocks)
+	if (dquot_freed_blocks && !(EXT3_I(inode)->i_state & EXT3_STATE_RESIZE))
 		DQUOT_FREE_BLOCK(inode, dquot_freed_blocks);
 	return;
 }
@@ -296,7 +374,7 @@ error_return:
  * data-writes at some point, and disable it for metadata allocations or
  * sync-data inodes.
  */
-static inline int ext3_test_allocatable(int nr, struct buffer_head *bh)
+static int ext3_test_allocatable(int nr, struct buffer_head *bh)
 {
 	int ret;
 	struct journal_head *jh = bh2jh(bh);
@@ -313,6 +391,33 @@ static inline int ext3_test_allocatable(int nr, struct buffer_head *bh)
 	return ret;
 }
 
+static int
+bitmap_search_next_usable_block(int start, struct buffer_head *bh,
+					int maxblocks)
+{
+	int next;
+	struct journal_head *jh = bh2jh(bh);
+
+	/*
+	 * The bitmap search --- search forward alternately through the actual
+	 * bitmap and the last-committed copy until we find a bit free in
+	 * both
+	 */
+	while (start < maxblocks) {
+		next = ext3_find_next_zero_bit(bh->b_data, maxblocks, start);
+		if (next >= maxblocks)
+			return -1;
+		if (ext3_test_allocatable(next, bh))
+			return next;
+		jbd_lock_bh_state(bh);
+		if (jh->b_committed_data)
+			start = ext3_find_next_zero_bit(jh->b_committed_data,
+						 	maxblocks, next);
+		jbd_unlock_bh_state(bh);
+	}
+	return -1;
+}
+
 /*
  * Find an allocatable block in a bitmap.  We honour both the bitmap and
  * its last-committed copy (if that exists), and perform the "most
@@ -325,7 +430,6 @@ find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)
 {
 	int here, next;
 	char *p, *r;
-	struct journal_head *jh = bh2jh(bh);
 
 	if (start > 0) {
 		/*
@@ -337,6 +441,8 @@ find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)
 		 * next 64-bit boundary is simple..
 		 */
 		int end_goal = (start + 63) & ~63;
+		if (end_goal > maxblocks)
+			end_goal = maxblocks;
 		here = ext3_find_next_zero_bit(bh->b_data, end_goal, start);
 		if (here < end_goal && ext3_test_allocatable(here, bh))
 			return here;
@@ -351,7 +457,7 @@ find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)
 	r = memscan(p, 0, (maxblocks - here + 7) >> 3);
 	next = (r - ((char *)bh->b_data)) << 3;
 
-	if (next < maxblocks && ext3_test_allocatable(next, bh))
+	if (next < maxblocks && next >= start && ext3_test_allocatable(next, bh))
 		return next;
 
 	/*
@@ -359,19 +465,8 @@ find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)
 	 * bitmap and the last-committed copy until we find a bit free in
 	 * both
 	 */
-	while (here < maxblocks) {
-		next = ext3_find_next_zero_bit(bh->b_data, maxblocks, here);
-		if (next >= maxblocks)
-			return -1;
-		if (ext3_test_allocatable(next, bh))
-			return next;
-		jbd_lock_bh_state(bh);
-		if (jh->b_committed_data)
-			here = ext3_find_next_zero_bit(jh->b_committed_data,
-						 	maxblocks, next);
-		jbd_unlock_bh_state(bh);
-	}
-	return -1;
+	here = bitmap_search_next_usable_block(here, bh, maxblocks);
+	return here;
 }
 
 /*
@@ -407,62 +502,494 @@ claim_block(spinlock_t *lock, int block, struct buffer_head *bh)
  */
 static int
 ext3_try_to_allocate(struct super_block *sb, handle_t *handle, int group,
-		struct buffer_head *bitmap_bh, int goal, int *errp)
+	struct buffer_head *bitmap_bh, int goal, struct reserve_window *my_rsv)
 {
-	int i;
-	int fatal;
-	int credits = 0;
-
-	*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 = ext3_journal_get_undo_access(handle, bitmap_bh, &credits);
-	if (fatal) {
-		*errp = fatal;
-		goto fail;
+	int group_first_block, start, end;
+
+	/* we do allocation within the reservation window if we have a window */
+	if (my_rsv) {
+		group_first_block =
+			le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
+			group * EXT3_BLOCKS_PER_GROUP(sb);
+		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 > EXT3_BLOCKS_PER_GROUP(sb))
+			/* reservation window crosses group boundary */
+			end = EXT3_BLOCKS_PER_GROUP(sb);
+		if ((start <= goal) && (goal < end))
+			start = goal;
+		else
+			goal = -1;
+	} else {
+		if (goal > 0)
+			start = goal;
+		else
+			start = 0;
+		end = EXT3_BLOCKS_PER_GROUP(sb);
 	}
 
+	BUG_ON(start > EXT3_BLOCKS_PER_GROUP(sb));
+
 repeat:
 	if (goal < 0 || !ext3_test_allocatable(goal, bitmap_bh)) {
-		goal = find_next_usable_block(goal, bitmap_bh,
-					EXT3_BLOCKS_PER_GROUP(sb));
+		goal = find_next_usable_block(start, bitmap_bh, end);
 		if (goal < 0)
 			goto fail_access;
-
-		for (i = 0; i < 7 && goal > 0 &&
-				ext3_test_allocatable(goal - 1, bitmap_bh);
-			i++, goal--);
+		if (!my_rsv) {
+			int i;
+
+			for (i = 0; i < 7 && goal > start &&
+					ext3_test_allocatable(goal - 1,
+								bitmap_bh);
+					i++, goal--)
+				;
+		}
 	}
+	start = goal;
 
 	if (!claim_block(sb_bgl_lock(EXT3_SB(sb), group), goal, bitmap_bh)) {
 		/*
 		 * The block was allocated by another thread, or it was
 		 * allocated and then freed by another thread
 		 */
+		start++;
 		goal++;
-		if (goal >= EXT3_BLOCKS_PER_GROUP(sb))
+		if (start >= end)
 			goto fail_access;
 		goto repeat;
 	}
+	if (my_rsv)
+		my_rsv->rsv_alloc_hit++;
+	return goal;
+fail_access:
+	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 necessary the list head of the whole filesystem
+ *
+ *		we have both head and start_block to assist the search
+ *		for the reservable space. The list start from head,
+ *		but we will shift to the place where start_block is,
+ *		then start from there, we looking for a resevable space.
+ *
+ *	@fs_rsv_head: per-filesystem reervation list head.
+ *
+ * 	@size: the target new reservation window size
+ * 	@group_first_block: the first block we consider to start
+ *			the real search from
+ *
+ * 	@last_block:
+ *		the maxium 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
+ *		possiblereservable space is out of this boundary.
+ *		This could handle the cross bounday 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 of of my size and has not
+ * 	been reserved.
+ *
+ *	on succeed, it returns the reservation window to be append to.
+ *	failed, return NULL.
+ */
+static inline
+struct reserve_window *find_next_reservable_window(
+				struct reserve_window *search_head,
+				struct reserve_window *fs_rsv_head,
+				unsigned long size, int *start_block,
+				int last_block)
+{
+	struct reserve_window *rsv;
+	int cur;
+
+	/* TODO:make the start of the reservation window byte alligned */
+	/*cur = *start_block & 8;*/
+	cur = *start_block;
+	rsv = list_entry(search_head->rsv_list.next,
+				struct reserve_window, rsv_list);
+	while (rsv != fs_rsv_head) {
+		if (cur + size <= rsv->rsv_start) {
+	 		/*
+			 * Found a reserveable space big enough.  We could
+			 * have a reservation across the group boundary here
+		 	 */
+			break;
+		}
+		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)...
+		 */
+		rsv = list_entry(rsv->rsv_list.next,
+				struct reserve_window, rsv_list);
+		if (cur > last_block)
+			return NULL;		/* fail */
+	}
+	/*
+	 * we come here either :
+	 * when we rearch to 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.
+	 */
+	*start_block = cur;
+	return list_entry(rsv->rsv_list.prev, struct reserve_window, rsv_list);
+}
+
+/**
+ * 	alloc_new_reservation()--allocate a new reservation window
+ *		if there is an existing reservation, discard it first
+ *		then allocate the new one from there
+ *		otherwise allocate the new reservation from the given
+ *		start block, or the beginning of the group, if a goal
+ *		is not given.
+ *
+ *		To make a new reservation, we search part of the filesystem
+ *		reservation list(the list that inside the group).
+ *
+ *		If we have a old reservation, the search goal is the end of
+ *		last reservation. If we do not have a old reservatio, then we
+ *		start from a given goal, or the first block of the group, if
+ *		the goal is not given.
+ *
+ *		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 reseravle space, then
+ *		start from the first free block, we search for next avalibale
+ *		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 is not overlap with other
+ *	reservation window.
+ *
+ *	failed: we failed to found a reservation window in this group
+ *
+ *	@rsv: the reservation
+ *
+ *	@goal: The goal.  It is where the search for a
+ *		free reservable space should start from.
+ *		if we have a old reservation, start_block is the end of
+ *		old reservation. Otherwise,
+ *		if we have a goal(goal >0 ), then start from there,
+ *		no goal(goal = -1), we start from the first block
+ *		of the group.
+ *
+ *	@sb: the super block
+ *	@group: the group we are trying to do allocate in
+ *	@bitmap_bh: the block group block bitmap
+ */
+static int alloc_new_reservation(struct reserve_window *my_rsv,
+		int goal, struct super_block *sb,
+		unsigned int group, struct buffer_head *bitmap_bh)
+{
+	struct reserve_window *search_head;
+	int group_first_block, group_end_block, start_block;
+	int first_free_block;
+	int reservable_space_start;
+	struct reserve_window *prev_rsv;
+	struct reserve_window *fs_rsv_head = &EXT3_SB(sb)->s_rsv_window_head;
+	unsigned long size;
+
+	group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
+				group * EXT3_BLOCKS_PER_GROUP(sb);
+	group_end_block = group_first_block + EXT3_BLOCKS_PER_GROUP(sb) - 1;
+
+	if (goal < 0)
+		start_block = group_first_block;
+	else
+		start_block = goal + group_first_block;
+
+	size = atomic_read(&my_rsv->rsv_goal_size);
+	/* if we have a old reservation, start the search from the old rsv */
+	if (!rsv_is_empty(my_rsv)) {
+		/*
+		 * if the old reservation is cross group boundary
+		 * 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))
+			return -1;
+
+		/* remember where we are before we discard the old one */
+		if (my_rsv->rsv_end + 1 > start_block)
+			start_block = my_rsv->rsv_end + 1;
+		search_head = my_rsv;
+		if ((my_rsv->rsv_alloc_hit > (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
+			/*
+			 * if we previously allocation hit ration is greater than half
+			 * we double the size of reservation window next time
+			 * otherwise keep the same
+			 */
+			size = size * 2;
+			if (size > EXT3_MAX_RESERVE_BLOCKS)
+				size = EXT3_MAX_RESERVE_BLOCKS;
+			atomic_set(&my_rsv->rsv_goal_size, size);
+		}
+	}
+	else {
+		/*
+		 * we don't have a reservation,
+		 * we set our goal(start_block) and
+		 * the list head for the search
+		 */
+		search_head = fs_rsv_head;
+	}
+
+	/*
+	 * find_next_reservable_window() simply find 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:
+	prev_rsv = find_next_reservable_window(search_head, fs_rsv_head, size,
+						&start_block, group_end_block);
+	if (prev_rsv == NULL)
+		goto failed;
+	reservable_space_start = start_block;
+	/*
+	 * 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.
+	 */
+	first_free_block = bitmap_search_next_usable_block(
+			reservable_space_start - group_first_block,
+			bitmap_bh, group_end_block - group_first_block + 1);
 
-	BUFFER_TRACE(bitmap_bh, "journal_dirty_metadata for bitmap block");
-	fatal = ext3_journal_dirty_metadata(handle, bitmap_bh);
+	if (first_free_block < 0) {
+		/*
+		 * no free block left on the bitmap, no point
+		 * to reserve the space. return failed.
+		 */
+		goto failed;
+	}
+	start_block = first_free_block + group_first_block;
+	/*
+	 * check if the first free block is within the
+	 * free space we just found
+	 */
+	if ((start_block >= reservable_space_start) &&
+	  (start_block < reservable_space_start + size))
+		goto found_rsv_window;
+	/*
+	 * if the first free bit we found is out of the reservable space
+	 * this means there is no free block on the reservable space
+	 * we should 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 = prev_rsv;
+	goto retry;
+
+found_rsv_window:
+	/*
+	 * great! the reservable space contains some free blocks.
+	 * if the search returns that we should add the new
+	 * window just next to where the old window, we don't
+ 	 * need to remove the old window first then add it to the
+	 * same place, just update the new start and new end.
+	 */
+	if (my_rsv != prev_rsv)  {
+		if (!rsv_is_empty(my_rsv))
+			rsv_window_remove(my_rsv);
+		rsv_window_add(my_rsv, prev_rsv);
+	}
+	my_rsv->rsv_start = reservable_space_start;
+	my_rsv->rsv_end = my_rsv->rsv_start + size - 1;
+	return 0;		/* succeed */
+failed:
+	return -1;		/* failed */
+}
+
+/*
+ * 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 start from the goal first. Then do the block
+ * allocation within the reservation window.
+ *
+ * This will aviod keep searching the reservation list again and again when
+ * someboday is looking for a free block(without reservation), and there are
+ * lots of free blocks, but they are all being reserved
+ *
+ * We use a sorted double linked list for the per-filesystem reservation list.
+ * The insert, remove and find a free space(non-reserved) operations for the
+ * sorted double linked list should be fast.
+ *
+ */
+static int
+ext3_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle,
+			unsigned int group, struct buffer_head *bitmap_bh,
+			int goal, struct reserve_window * my_rsv,
+			int *errp)
+{
+	spinlock_t *rsv_lock;
+	unsigned long group_first_block;
+	int ret = 0;
+	int fatal;
+	int credits = 0;
+
+	*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 = ext3_journal_get_undo_access(handle, bitmap_bh, &credits);
 	if (fatal) {
 		*errp = fatal;
-		goto fail;
+		return -1;
+	}
+
+	/*
+	 * we don't deal with reservation when
+	 * filesystem is mounted without reservation
+	 * or the file is not a regular file
+	 * of last attemp of allocating a block with reservation turn on failed
+	 */
+	if (my_rsv == NULL ) {
+		ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh, goal, NULL);
+		goto out;
+	}
+	rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;
+	/*
+	 * goal is a group relative block number (if there is a goal)
+	 * 0 < goal < EXT3_BLOCKS_PER_GROUP(sb)
+	 * first block is a filesystem wide block number
+	 * first block is the block number of the first block in this group
+	 */
+	group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
+			group * EXT3_BLOCKS_PER_GROUP(sb);
+
+	/*
+	 * Basically we will allocate a new block from inode's reservation
+	 * window.
+	 *
+	 * We need to allocate a new reservation window, if:
+	 * a) inode does not have a reservation window; or
+	 * b) last attemp of allocating a block from existing reservation
+	 *    failed; or
+	 * c) we come here with a goal and with a reservation window
+	 *
+	 * We do not need to allocate a new reservation window if we come here
+	 * at the beginning with a goal and the goal is inside the window, or
+	 * or we don't have a goal but already have a reservation window.
+	 * then we could go to allocate from the reservation window directly.
+	 */
+	while (1) {
+		if (rsv_is_empty(my_rsv) || (ret < 0) ||
+			!goal_in_my_reservation(my_rsv, goal, group, sb)) {
+			spin_lock(rsv_lock);
+			ret = alloc_new_reservation(my_rsv, goal, sb,
+							group, bitmap_bh);
+			spin_unlock(rsv_lock);
+			if (ret < 0)
+				break;			/* failed */
+
+			if (!goal_in_my_reservation(my_rsv, goal, group, sb))
+				goal = -1;
+		}
+		if ((my_rsv->rsv_start >= group_first_block + EXT3_BLOCKS_PER_GROUP(sb))
+			|| (my_rsv->rsv_end < group_first_block))
+			BUG();
+		ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh, goal,
+					my_rsv);
+		if (ret >= 0)
+			break;				/* succeed */
+	}
+out:
+	if (ret >= 0) {
+		BUFFER_TRACE(bitmap_bh, "journal_dirty_metadata for "
+					"bitmap block");
+		fatal = ext3_journal_dirty_metadata(handle, bitmap_bh);
+		if (fatal) {
+			*errp = fatal;
+			return -1;
+		}
+		return ret;
 	}
-	return goal;
 
-fail_access:
 	BUFFER_TRACE(bitmap_bh, "journal_release_buffer");
 	ext3_journal_release_buffer(handle, bitmap_bh, credits);
-fail:
-	return -1;
+	return ret;
+}
+
+static int ext3_has_free_blocks(struct ext3_sb_info *sbi)
+{
+	int free_blocks, root_blocks;
+
+	free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
+	root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
+	if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
+		sbi->s_resuid != current->fsuid &&
+		(sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
+		return 0;
+	}
+	return 1;
+}
+
+/*
+ * ext3_should_retry_alloc() is called when ENOSPC is returned, and if
+ * it is profitable to retry the operation, this function will wait
+ * for the current or commiting transaction to complete, and then
+ * return TRUE.
+ */
+int ext3_should_retry_alloc(struct super_block *sb, int *retries)
+{
+	if (!ext3_has_free_blocks(EXT3_SB(sb)) || (*retries)++ > 3)
+		return 0;
+
+	jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
+
+	return journal_force_commit_nested(EXT3_SB(sb)->s_journal);
 }
 
 /*
@@ -473,23 +1000,24 @@ fail:
  * bitmap, and then for any free bit if that fails.
  * This function also updates quota and i_blocks field.
  */
-int
-ext3_new_block(handle_t *handle, struct inode *inode, unsigned long goal,
-		u32 *prealloc_count, u32 *prealloc_block, int *errp)
+int ext3_new_block(handle_t *handle, struct inode *inode,
+			unsigned long goal, int *errp)
 {
-	struct buffer_head *bitmap_bh = NULL;	/* bh */
-	struct buffer_head *gdp_bh;		/* bh2 */
-	int group_no;				/* i */
-	int ret_block;				/* j */
-	int bgi;				/* blockgroup iteration index */
-	int target_block;			/* tmp */
+	struct buffer_head *bitmap_bh = NULL;
+	struct buffer_head *gdp_bh;
+	int group_no;
+	int goal_group;
+	int ret_block;
+	int bgi;			/* blockgroup iteration index */
+	int target_block;
 	int fatal = 0, err;
 	int performed_allocation = 0;
-	int free_blocks, root_blocks;
+	int free_blocks;
 	struct super_block *sb;
 	struct ext3_group_desc *gdp;
 	struct ext3_super_block *es;
 	struct ext3_sb_info *sbi;
+	struct reserve_window *my_rsv = NULL;
 #ifdef EXT3FS_DEBUG
 	static int goal_hits, goal_attempts;
 #endif
@@ -511,12 +1039,9 @@ ext3_new_block(handle_t *handle, struct inode *inode, unsigned long goal,
 	sbi = EXT3_SB(sb);
 	es = EXT3_SB(sb)->s_es;
 	ext3_debug("goal=%lu.\n", goal);
-
-	free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
-	root_blocks = le32_to_cpu(es->s_r_blocks_count);
-	if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
-		sbi->s_resuid != current->fsuid &&
-		(sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
+	if (test_opt(sb, RESERVATION) && S_ISREG(inode->i_mode))
+		my_rsv = &EXT3_I(inode)->i_rsv_window;
+	if (!ext3_has_free_blocks(sbi)) {
 		*errp = -ENOSPC;
 		goto out;
 	}
@@ -533,6 +1058,8 @@ ext3_new_block(handle_t *handle, struct inode *inode, unsigned long goal,
 	if (!gdp)
 		goto io_error;
 
+	goal_group = group_no;
+retry:
 	free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
 	if (free_blocks > 0) {
 		ret_block = ((goal - le32_to_cpu(es->s_first_data_block)) %
@@ -540,8 +1067,8 @@ ext3_new_block(handle_t *handle, struct inode *inode, unsigned long goal,
 		bitmap_bh = read_block_bitmap(sb, group_no);
 		if (!bitmap_bh)
 			goto io_error;
-		ret_block = ext3_try_to_allocate(sb, handle, group_no,
-					bitmap_bh, ret_block, &fatal);
+		ret_block = ext3_try_to_allocate_with_rsv(sb, handle, group_no,
+					bitmap_bh, ret_block, my_rsv, &fatal);
 		if (fatal)
 			goto out;
 		if (ret_block >= 0)
@@ -569,14 +1096,25 @@ ext3_new_block(handle_t *handle, struct inode *inode, unsigned long goal,
 		bitmap_bh = read_block_bitmap(sb, group_no);
 		if (!bitmap_bh)
 			goto io_error;
-		ret_block = ext3_try_to_allocate(sb, handle, group_no,
-						bitmap_bh, -1, &fatal);
+		ret_block = ext3_try_to_allocate_with_rsv(sb, handle, group_no,
+					bitmap_bh, -1, my_rsv, &fatal);
 		if (fatal)
 			goto out;
 		if (ret_block >= 0) 
 			goto allocated;
 	}
-
+	/*
+	 * We may end up a bogus ealier ENOSPC error due to
+	 * filesystem is "full" of reservations, but
+	 * there maybe indeed free blocks avaliable on disk
+	 * In this case, we just forget about the reservations
+	 * just do block allocation as without reservations.
+	 */
+	if (my_rsv) {
+		my_rsv = NULL;
+		group_no = goal_group;
+		goto retry;
+	}
 	/* No space left on the device */
 	*errp = -ENOSPC;
 	goto out;