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| author | Kent Overstreet <kent.overstreet@linux.dev> | 2023-11-04 13:49:31 -0400 |
|---|---|---|
| committer | Kent Overstreet <kent.overstreet@linux.dev> | 2023-11-04 22:19:13 -0400 |
| commit | 9fcdd23b6eea3f04475cd9cfb4497f6e26906061 (patch) | |
| tree | e17bdb92371b1c893b47d669faf4f41a070b0ebb /fs/bcachefs/io_write.c | |
| parent | d3c7727bb9269c7f7a2f17ef76b9e5c9b8cc8863 (diff) | |
| download | linux-9fcdd23b6eea3f04475cd9cfb4497f6e26906061.tar.gz linux-9fcdd23b6eea3f04475cd9cfb4497f6e26906061.tar.bz2 linux-9fcdd23b6eea3f04475cd9cfb4497f6e26906061.zip | |
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 <kent.overstreet@linux.dev>
Diffstat (limited to 'fs/bcachefs/io_write.c')
| -rw-r--r-- | fs/bcachefs/io_write.c | 11 |
1 files changed, 11 insertions, 0 deletions
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; |