btrfs: add missing unlikely to if branches leading to a DEBUG_WARN()

If statement branches that lead to a DEBUG_WARN() are unexpected to happen
and in most places we surround their expressions with the unlikely tag,
however a few places are missing. Add the unlikely tag to those missing
places to make it explicit to a reader that it's not expected and to hint
the compiler to generate better code.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: fdmanana

fs/btrfs/block-group.c

@@ -4117,7 +4117,7 @@ int btrfs_force_chunk_alloc(struct btrfs_trans_handle *trans, u64 type)
 	struct btrfs_space_info *space_info;
 
 	space_info = btrfs_find_space_info(trans->fs_info, type);
-	if (!space_info) {
+	if (unlikely(!space_info)) {
 		DEBUG_WARN();
 		return -EINVAL;
 	}

fs/btrfs/disk-io.c

@@ -4398,7 +4398,7 @@ void __cold close_ctree(struct btrfs_fs_info *fs_info)
 	ASSERT(list_empty(&fs_info->delayed_iputs));
 	set_bit(BTRFS_FS_CLOSING_DONE, &fs_info->flags);
 
-	if (btrfs_check_quota_leak(fs_info)) {
+	if (unlikely(btrfs_check_quota_leak(fs_info))) {
 		DEBUG_WARN("qgroup reserved space leaked");
 		btrfs_err(fs_info, "qgroup reserved space leaked");
 	}

fs/btrfs/extent-tree.c

@@ -6655,7 +6655,7 @@ static int btrfs_trim_free_extents_throttle(struct btrfs_device *device,
 		start = max(start, cur_start);
 
 		/* Check if there are any CHUNK_* bits left */
-		if (start > device->total_bytes) {
+		if (unlikely(start > device->total_bytes)) {
 			DEBUG_WARN();
 			btrfs_warn(fs_info,
 "ignoring attempt to trim beyond device size: offset %llu length %llu device %s device size %llu",

fs/btrfs/free-space-tree.c

@@ -109,7 +109,7 @@ struct btrfs_free_space_info *btrfs_search_free_space_info(
 	ret = btrfs_search_slot(trans, root, &key, path, 0, cow);
 	if (ret < 0)
 		return ERR_PTR(ret);
-	if (ret != 0) {
+	if (unlikely(ret != 0)) {
 		btrfs_warn(fs_info, "missing free space info for %llu",
 			   block_group->start);
 		DEBUG_WARN();

fs/btrfs/inode.c

@@ -755,7 +755,7 @@ static inline int inode_need_compress(struct btrfs_inode *inode, u64 start,
 {
 	struct btrfs_fs_info *fs_info = inode->root->fs_info;
 
-	if (!btrfs_inode_can_compress(inode)) {
+	if (unlikely(!btrfs_inode_can_compress(inode))) {
 		DEBUG_WARN("BTRFS: unexpected compression for ino %llu", btrfs_ino(inode));
 		return 0;
 	}

fs/btrfs/qgroup.c

@@ -1836,9 +1836,9 @@ int btrfs_remove_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid)
 	 * Thus its reserved space should all be zero, no matter if qgroup
 	 * is consistent or the mode.
 	 */
-	if (qgroup->rsv.values[BTRFS_QGROUP_RSV_DATA] ||
-	    qgroup->rsv.values[BTRFS_QGROUP_RSV_META_PREALLOC] ||
-	    qgroup->rsv.values[BTRFS_QGROUP_RSV_META_PERTRANS]) {
+	if (unlikely(qgroup->rsv.values[BTRFS_QGROUP_RSV_DATA] ||
+		     qgroup->rsv.values[BTRFS_QGROUP_RSV_META_PREALLOC] ||
+		     qgroup->rsv.values[BTRFS_QGROUP_RSV_META_PERTRANS])) {
 		DEBUG_WARN();
 		btrfs_warn_rl(fs_info,
 "to be deleted qgroup %u/%llu has non-zero numbers, data %llu meta prealloc %llu meta pertrans %llu",
@@ -1857,8 +1857,8 @@ int btrfs_remove_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid)
 	 */
 	if (btrfs_qgroup_mode(fs_info) == BTRFS_QGROUP_MODE_FULL &&
 	    !(fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT)) {
-		if (qgroup->rfer || qgroup->excl ||
-		    qgroup->rfer_cmpr || qgroup->excl_cmpr) {
+		if (unlikely(qgroup->rfer || qgroup->excl ||
+			     qgroup->rfer_cmpr || qgroup->excl_cmpr)) {
 			DEBUG_WARN();
 			qgroup_mark_inconsistent(fs_info,
 				"to be deleted qgroup %u/%llu has non-zero numbers, rfer %llu rfer_cmpr %llu excl %llu excl_cmpr %llu",
@@ -4800,9 +4800,9 @@ int btrfs_qgroup_add_swapped_blocks(struct btrfs_root *subvol_root,
 
 		entry = rb_entry(node, struct btrfs_qgroup_swapped_block, node);
 
-		if (entry->subvol_generation != block->subvol_generation ||
-		    entry->reloc_bytenr != block->reloc_bytenr ||
-		    entry->reloc_generation != block->reloc_generation) {
+		if (unlikely(entry->subvol_generation != block->subvol_generation ||
+			     entry->reloc_bytenr != block->reloc_bytenr ||
+			     entry->reloc_generation != block->reloc_generation)) {
 			/*
 			 * Duplicated but mismatch entry found.  Shouldn't happen.
 			 * Marking qgroup inconsistent should be enough for end

fs/btrfs/volumes.c

@@ -6081,7 +6081,7 @@ struct btrfs_block_group *btrfs_create_chunk(struct btrfs_trans_handle *trans,
 
 	lockdep_assert_held(&info->chunk_mutex);
 
-	if (!alloc_profile_is_valid(type, 0)) {
+	if (unlikely(!alloc_profile_is_valid(type, 0))) {
 		DEBUG_WARN("invalid alloc profile for type %llu", type);
 		return ERR_PTR(-EINVAL);
 	}
@@ -6092,7 +6092,7 @@ struct btrfs_block_group *btrfs_create_chunk(struct btrfs_trans_handle *trans,
 		return ERR_PTR(-ENOSPC);
 	}
 
-	if (!(type & BTRFS_BLOCK_GROUP_TYPE_MASK)) {
+	if (unlikely(!(type & BTRFS_BLOCK_GROUP_TYPE_MASK))) {
 		btrfs_err(info, "invalid chunk type 0x%llx requested", type);
 		DEBUG_WARN();
 		return ERR_PTR(-EINVAL);
@@ -6262,7 +6262,7 @@ static noinline int init_first_rw_device(struct btrfs_trans_handle *trans)
 
 	alloc_profile = btrfs_metadata_alloc_profile(fs_info);
 	meta_space_info = btrfs_find_space_info(fs_info, alloc_profile);
-	if (!meta_space_info) {
+	if (unlikely(!meta_space_info)) {
 		DEBUG_WARN();
 		return -EINVAL;
 	}
@@ -6272,7 +6272,7 @@ static noinline int init_first_rw_device(struct btrfs_trans_handle *trans)
 
 	alloc_profile = btrfs_system_alloc_profile(fs_info);
 	sys_space_info = btrfs_find_space_info(fs_info, alloc_profile);
-	if (!sys_space_info) {
+	if (unlikely(!sys_space_info)) {
 		DEBUG_WARN();
 		return -EINVAL;
 	}