1 files changed, 52 insertions, 93 deletions

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 81296c57405..6c4e2baa929 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -1543,29 +1543,26 @@ again:
 	end = bitmap_info->offset + (u64)(BITS_PER_BITMAP * ctl->unit) - 1;
 
 	/*
-	 * XXX - this can go away after a few releases.
-	 *
-	 * since the only user of btrfs_remove_free_space is the tree logging
-	 * stuff, and the only way to test that is under crash conditions, we
-	 * want to have this debug stuff here just in case somethings not
-	 * working.  Search the bitmap for the space we are trying to use to
-	 * make sure its actually there.  If its not there then we need to stop
-	 * because something has gone wrong.
+	 * We need to search for bits in this bitmap.  We could only cover some
+	 * of the extent in this bitmap thanks to how we add space, so we need
+	 * to search for as much as it as we can and clear that amount, and then
+	 * go searching for the next bit.
 	 */
 	search_start = *offset;
-	search_bytes = *bytes;
+	search_bytes = ctl->unit;
 	search_bytes = min(search_bytes, end - search_start + 1);
 	ret = search_bitmap(ctl, bitmap_info, &search_start, &search_bytes);
 	BUG_ON(ret < 0 || search_start != *offset);
 
-	if (*offset > bitmap_info->offset && *offset + *bytes > end) {
-		bitmap_clear_bits(ctl, bitmap_info, *offset, end - *offset + 1);
-		*bytes -= end - *offset + 1;
-		*offset = end + 1;
-	} else if (*offset >= bitmap_info->offset && *offset + *bytes <= end) {
-		bitmap_clear_bits(ctl, bitmap_info, *offset, *bytes);
-		*bytes = 0;
-	}
+	/* We may have found more bits than what we need */
+	search_bytes = min(search_bytes, *bytes);
+
+	/* Cannot clear past the end of the bitmap */
+	search_bytes = min(search_bytes, end - search_start + 1);
+
+	bitmap_clear_bits(ctl, bitmap_info, search_start, search_bytes);
+	*offset += search_bytes;
+	*bytes -= search_bytes;
 
 	if (*bytes) {
 		struct rb_node *next = rb_next(&bitmap_info->offset_index);
@@ -1596,7 +1593,7 @@ again:
 		 * everything over again.
 		 */
 		search_start = *offset;
-		search_bytes = *bytes;
+		search_bytes = ctl->unit;
 		ret = search_bitmap(ctl, bitmap_info, &search_start,
 				    &search_bytes);
 		if (ret < 0 || search_start != *offset)
@@ -1879,12 +1876,14 @@ int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
 {
 	struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
 	struct btrfs_free_space *info;
-	struct btrfs_free_space *next_info = NULL;
 	int ret = 0;
 
 	spin_lock(&ctl->tree_lock);
 
 again:
+	if (!bytes)
+		goto out_lock;
+
 	info = tree_search_offset(ctl, offset, 0, 0);
 	if (!info) {
 		/*
@@ -1905,88 +1904,48 @@ again:
 		}
 	}
 
-	if (info->bytes < bytes && rb_next(&info->offset_index)) {
-		u64 end;
-		next_info = rb_entry(rb_next(&info->offset_index),
-					     struct btrfs_free_space,
-					     offset_index);
-
-		if (next_info->bitmap)
-			end = next_info->offset +
-			      BITS_PER_BITMAP * ctl->unit - 1;
-		else
-			end = next_info->offset + next_info->bytes;
-
-		if (next_info->bytes < bytes ||
-		    next_info->offset > offset || offset > end) {
-			printk(KERN_CRIT "Found free space at %llu, size %llu,"
-			      " trying to use %llu\n",
-			      (unsigned long long)info->offset,
-			      (unsigned long long)info->bytes,
-			      (unsigned long long)bytes);
-			WARN_ON(1);
-			ret = -EINVAL;
-			goto out_lock;
-		}
-
-		info = next_info;
-	}
-
-	if (info->bytes == bytes) {
+	if (!info->bitmap) {
 		unlink_free_space(ctl, info);
-		if (info->bitmap) {
-			kfree(info->bitmap);
-			ctl->total_bitmaps--;
-		}
-		kmem_cache_free(btrfs_free_space_cachep, info);
-		ret = 0;
-		goto out_lock;
-	}
-
-	if (!info->bitmap && info->offset == offset) {
-		unlink_free_space(ctl, info);
-		info->offset += bytes;
-		info->bytes -= bytes;
-		ret = link_free_space(ctl, info);
-		WARN_ON(ret);
-		goto out_lock;
-	}
+		if (offset == info->offset) {
+			u64 to_free = min(bytes, info->bytes);
+
+			info->bytes -= to_free;
+			info->offset += to_free;
+			if (info->bytes) {
+				ret = link_free_space(ctl, info);
+				WARN_ON(ret);
+			} else {
+				kmem_cache_free(btrfs_free_space_cachep, info);
+			}
 
-	if (!info->bitmap && info->offset <= offset &&
-	    info->offset + info->bytes >= offset + bytes) {
-		u64 old_start = info->offset;
-		/*
-		 * we're freeing space in the middle of the info,
-		 * this can happen during tree log replay
-		 *
-		 * first unlink the old info and then
-		 * insert it again after the hole we're creating
-		 */
-		unlink_free_space(ctl, info);
-		if (offset + bytes < info->offset + info->bytes) {
-			u64 old_end = info->offset + info->bytes;
+			offset += to_free;
+			bytes -= to_free;
+			goto again;
+		} else {
+			u64 old_end = info->bytes + info->offset;
 
-			info->offset = offset + bytes;
-			info->bytes = old_end - info->offset;
+			info->bytes = offset - info->offset;
 			ret = link_free_space(ctl, info);
 			WARN_ON(ret);
 			if (ret)
 				goto out_lock;
-		} else {
-			/* the hole we're creating ends at the end
-			 * of the info struct, just free the info
-			 */
-			kmem_cache_free(btrfs_free_space_cachep, info);
-		}
-		spin_unlock(&ctl->tree_lock);
 
-		/* step two, insert a new info struct to cover
-		 * anything before the hole
-		 */
-		ret = btrfs_add_free_space(block_group, old_start,
-					   offset - old_start);
-		WARN_ON(ret); /* -ENOMEM */
-		goto out;
+			/* Not enough bytes in this entry to satisfy us */
+			if (old_end < offset + bytes) {
+				bytes -= old_end - offset;
+				offset = old_end;
+				goto again;
+			} else if (old_end == offset + bytes) {
+				/* all done */
+				goto out_lock;
+			}
+			spin_unlock(&ctl->tree_lock);
+
+			ret = btrfs_add_free_space(block_group, offset + bytes,
+						   old_end - (offset + bytes));
+			WARN_ON(ret);
+			goto out;
+		}
 	}
 
 	ret = remove_from_bitmap(ctl, info, &offset, &bytes);