Commit 9fcdd23b authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcachefs: Add a comment for BTREE_INSERT_NOJOURNAL usage 



BTREE_INSERT_NOJOURNAL is primarily used for a performance optimization
related to inode updates and fsync - document it.

Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
parent d3c7727b

fs/bcachefs/btree_iter.c

+1 −1
Original line number Diff line number Diff line
@@ -257,7 +257,7 @@ static void bch2_btree_iter_verify(struct btree_iter *iter) 


	BUG_ON(!(iter->flags & __BTREE_ITER_ALL_SNAPSHOTS) &&

	       (iter->flags & BTREE_ITER_ALL_SNAPSHOTS) &&

	       !btree_type_has_snapshots(iter->btree_id));

	       !btree_type_has_snapshot_field(iter->btree_id));



	if (iter->update_path)

		bch2_btree_path_verify(trans, iter->update_path);

fs/bcachefs/btree_iter.h

+1 −2
Original line number Diff line number Diff line
@@ -416,8 +416,7 @@ static inline unsigned __bch2_btree_iter_flags(struct btree_trans *trans, 
		flags |= BTREE_ITER_IS_EXTENTS;



	if (!(flags & __BTREE_ITER_ALL_SNAPSHOTS) &&

	    !btree_type_has_snapshot_field(btree_id) &&

	    !btree_type_has_snapshots(btree_id))

	    !btree_type_has_snapshot_field(btree_id))

		flags &= ~BTREE_ITER_ALL_SNAPSHOTS;



	if (!(flags & BTREE_ITER_ALL_SNAPSHOTS) &&

fs/bcachefs/btree_types.h

+1 −1
Original line number Diff line number Diff line
@@ -713,7 +713,7 @@ static inline bool btree_type_has_snapshots(enum btree_id id) 
static inline bool btree_type_has_snapshot_field(enum btree_id id)

{

	const unsigned mask = 0

#define x(name, nr, flags, ...)	|((!!((flags) & BTREE_ID_SNAPSHOT_FIELD)) << nr)

#define x(name, nr, flags, ...)	|((!!((flags) & (BTREE_ID_SNAPSHOT_FIELD|BTREE_ID_SNAPSHOTS))) << nr)

	BCH_BTREE_IDS()

#undef x

	;

fs/bcachefs/io_write.c

+11 −0
Original line number Diff line number Diff line
@@ -202,6 +202,17 @@ static inline int bch2_extent_update_i_size_sectors(struct btree_trans *trans, 
	struct btree_iter iter;

	struct bkey_i *k;

	struct bkey_i_inode_v3 *inode;

	/*

	 * Crazy performance optimization:

	 * Every extent update needs to also update the inode: the inode trigger

	 * will set bi->journal_seq to the journal sequence number of this

	 * transaction - for fsync.

	 *

	 * But if that's the only reason we're updating the inode (we're not

	 * updating bi_size or bi_sectors), then we don't need the inode update

	 * to be journalled - if we crash, the bi_journal_seq update will be

	 * lost, but that's fine.

	 */

	unsigned inode_update_flags = BTREE_UPDATE_NOJOURNAL;

	int ret;