diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index a18b7bc..93a0191 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2232,6 +2232,7 @@
 			       u64 num_bytes, u64 *actual_bytes);
 int btrfs_force_chunk_alloc(struct btrfs_trans_handle *trans,
 			    struct btrfs_root *root, u64 type);
+int btrfs_trim_fs(struct btrfs_root *root, struct fstrim_range *range);
 
 /* ctree.c */
 int btrfs_bin_search(struct extent_buffer *eb, struct btrfs_key *key,
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index e990d2d..1efeda3 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -440,7 +440,7 @@
 	 * allocate blocks for the tree root we can't do the fast caching since
 	 * we likely hold important locks.
 	 */
-	if (!trans->transaction->in_commit &&
+	if (trans && (!trans->transaction->in_commit) &&
 	    (root && root != root->fs_info->tree_root)) {
 		spin_lock(&cache->lock);
 		if (cache->cached != BTRFS_CACHE_NO) {
@@ -8778,3 +8778,51 @@
 {
 	return btrfs_discard_extent(root, bytenr, num_bytes, actual_bytes);
 }
+
+int btrfs_trim_fs(struct btrfs_root *root, struct fstrim_range *range)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_block_group_cache *cache = NULL;
+	u64 group_trimmed;
+	u64 start;
+	u64 end;
+	u64 trimmed = 0;
+	int ret = 0;
+
+	cache = btrfs_lookup_block_group(fs_info, range->start);
+
+	while (cache) {
+		if (cache->key.objectid >= (range->start + range->len)) {
+			btrfs_put_block_group(cache);
+			break;
+		}
+
+		start = max(range->start, cache->key.objectid);
+		end = min(range->start + range->len,
+				cache->key.objectid + cache->key.offset);
+
+		if (end - start >= range->minlen) {
+			if (!block_group_cache_done(cache)) {
+				ret = cache_block_group(cache, NULL, root, 0);
+				if (!ret)
+					wait_block_group_cache_done(cache);
+			}
+			ret = btrfs_trim_block_group(cache,
+						     &group_trimmed,
+						     start,
+						     end,
+						     range->minlen);
+
+			trimmed += group_trimmed;
+			if (ret) {
+				btrfs_put_block_group(cache);
+				break;
+			}
+		}
+
+		cache = next_block_group(fs_info->tree_root, cache);
+	}
+
+	range->len = trimmed;
+	return ret;
+}
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index f03ef97..0037427 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -2178,3 +2178,95 @@
 	cluster->block_group = NULL;
 }
 
+int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
+			   u64 *trimmed, u64 start, u64 end, u64 minlen)
+{
+	struct btrfs_free_space *entry = NULL;
+	struct btrfs_fs_info *fs_info = block_group->fs_info;
+	u64 bytes = 0;
+	u64 actually_trimmed;
+	int ret = 0;
+
+	*trimmed = 0;
+
+	while (start < end) {
+		spin_lock(&block_group->tree_lock);
+
+		if (block_group->free_space < minlen) {
+			spin_unlock(&block_group->tree_lock);
+			break;
+		}
+
+		entry = tree_search_offset(block_group, start, 0, 1);
+		if (!entry)
+			entry = tree_search_offset(block_group,
+						   offset_to_bitmap(block_group,
+								    start),
+						   1, 1);
+
+		if (!entry || entry->offset >= end) {
+			spin_unlock(&block_group->tree_lock);
+			break;
+		}
+
+		if (entry->bitmap) {
+			ret = search_bitmap(block_group, entry, &start, &bytes);
+			if (!ret) {
+				if (start >= end) {
+					spin_unlock(&block_group->tree_lock);
+					break;
+				}
+				bytes = min(bytes, end - start);
+				bitmap_clear_bits(block_group, entry,
+						  start, bytes);
+				if (entry->bytes == 0)
+					free_bitmap(block_group, entry);
+			} else {
+				start = entry->offset + BITS_PER_BITMAP *
+					block_group->sectorsize;
+				spin_unlock(&block_group->tree_lock);
+				ret = 0;
+				continue;
+			}
+		} else {
+			start = entry->offset;
+			bytes = min(entry->bytes, end - start);
+			unlink_free_space(block_group, entry);
+			kfree(entry);
+		}
+
+		spin_unlock(&block_group->tree_lock);
+
+		if (bytes >= minlen) {
+			int update_ret;
+			update_ret = btrfs_update_reserved_bytes(block_group,
+								 bytes, 1, 1);
+
+			ret = btrfs_error_discard_extent(fs_info->extent_root,
+							 start,
+							 bytes,
+							 &actually_trimmed);
+
+			btrfs_add_free_space(block_group,
+					     start, bytes);
+			if (!update_ret)
+				btrfs_update_reserved_bytes(block_group,
+							    bytes, 0, 1);
+
+			if (ret)
+				break;
+			*trimmed += actually_trimmed;
+		}
+		start += bytes;
+		bytes = 0;
+
+		if (fatal_signal_pending(current)) {
+			ret = -ERESTARTSYS;
+			break;
+		}
+
+		cond_resched();
+	}
+
+	return ret;
+}
diff --git a/fs/btrfs/free-space-cache.h b/fs/btrfs/free-space-cache.h
index e49ca5c..65c3b93 100644
--- a/fs/btrfs/free-space-cache.h
+++ b/fs/btrfs/free-space-cache.h
@@ -68,4 +68,6 @@
 int btrfs_return_cluster_to_free_space(
 			       struct btrfs_block_group_cache *block_group,
 			       struct btrfs_free_cluster *cluster);
+int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
+			   u64 *trimmed, u64 start, u64 end, u64 minlen);
 #endif
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 32c980a..649f47d 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -40,6 +40,7 @@
 #include <linux/xattr.h>
 #include <linux/vmalloc.h>
 #include <linux/slab.h>
+#include <linux/blkdev.h>
 #include "compat.h"
 #include "ctree.h"
 #include "disk-io.h"
@@ -258,6 +259,49 @@
 	return put_user(inode->i_generation, arg);
 }
 
+static noinline int btrfs_ioctl_fitrim(struct file *file, void __user *arg)
+{
+	struct btrfs_root *root = fdentry(file)->d_sb->s_fs_info;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_device *device;
+	struct request_queue *q;
+	struct fstrim_range range;
+	u64 minlen = ULLONG_MAX;
+	u64 num_devices = 0;
+	int ret;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	mutex_lock(&fs_info->fs_devices->device_list_mutex);
+	list_for_each_entry(device, &fs_info->fs_devices->devices, dev_list) {
+		if (!device->bdev)
+			continue;
+		q = bdev_get_queue(device->bdev);
+		if (blk_queue_discard(q)) {
+			num_devices++;
+			minlen = min((u64)q->limits.discard_granularity,
+				     minlen);
+		}
+	}
+	mutex_unlock(&fs_info->fs_devices->device_list_mutex);
+	if (!num_devices)
+		return -EOPNOTSUPP;
+
+	if (copy_from_user(&range, arg, sizeof(range)))
+		return -EFAULT;
+
+	range.minlen = max(range.minlen, minlen);
+	ret = btrfs_trim_fs(root, &range);
+	if (ret < 0)
+		return ret;
+
+	if (copy_to_user(arg, &range, sizeof(range)))
+		return -EFAULT;
+
+	return 0;
+}
+
 static noinline int create_subvol(struct btrfs_root *root,
 				  struct dentry *dentry,
 				  char *name, int namelen,
@@ -2426,6 +2470,8 @@
 		return btrfs_ioctl_setflags(file, argp);
 	case FS_IOC_GETVERSION:
 		return btrfs_ioctl_getversion(file, argp);
+	case FITRIM:
+		return btrfs_ioctl_fitrim(file, argp);
 	case BTRFS_IOC_SNAP_CREATE:
 		return btrfs_ioctl_snap_create(file, argp, 0);
 	case BTRFS_IOC_SNAP_CREATE_V2: