From 9fcdd23b6eea3f04475cd9cfb4497f6e26906061 Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Sat, 4 Nov 2023 13:49:31 -0400 Subject: 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: Kent Overstreet --- fs/bcachefs/btree_iter.c | 2 +- fs/bcachefs/btree_iter.h | 3 +-- fs/bcachefs/btree_types.h | 2 +- fs/bcachefs/io_write.c | 11 +++++++++++ 4 files changed, 14 insertions(+), 4 deletions(-) (limited to 'fs/bcachefs') diff --git a/fs/bcachefs/btree_iter.c b/fs/bcachefs/btree_iter.c index af98545e0f35..c2adf3fbb0b3 100644 --- a/fs/bcachefs/btree_iter.c +++ b/fs/bcachefs/btree_iter.c @@ -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); diff --git a/fs/bcachefs/btree_iter.h b/fs/bcachefs/btree_iter.h index 967cde33d433..85e7cb52f6b6 100644 --- a/fs/bcachefs/btree_iter.h +++ b/fs/bcachefs/btree_iter.h @@ -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) && diff --git a/fs/bcachefs/btree_types.h b/fs/bcachefs/btree_types.h index a685883e5405..3ab773005484 100644 --- a/fs/bcachefs/btree_types.h +++ b/fs/bcachefs/btree_types.h @@ -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 ; diff --git a/fs/bcachefs/io_write.c b/fs/bcachefs/io_write.c index 613f38436640..4eb0eda723ab 100644 --- a/fs/bcachefs/io_write.c +++ b/fs/bcachefs/io_write.c @@ -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; -- cgit