6.7-stable review patch. If anyone has any objections, please let me know.
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From: Christoph Hellwig hch@lst.de
commit 3e44f325f6f75078cdcd44cd337f517ba3650d05 upstream.
REQ_OP_FLUSH is only for internal use in the blk-mq and request based drivers. File systems and other block layer consumers must use REQ_OP_WRITE | REQ_PREFLUSH as documented in Documentation/block/writeback_cache_control.rst.
While REQ_OP_FLUSH appears to work for blk-mq drivers it does not get the proper flush state machine handling, and completely fails for any bio based drivers, including all the stacking drivers. The block layer will also get a check in 6.8 to reject this use case entirely.
[Note: completely untested, but as this never got fixed since the original bug report in November:
https://bugzilla.kernel.org/show_bug.cgi?id=218184
and the the discussion in December:
https://lore.kernel.org/all/20231221053016.72cqcfg46vxwohcj@moria.home.lan/T...
this seems to be best way to force it]
Signed-off-by: Christoph Hellwig hch@lst.de Signed-off-by: Kent Overstreet kent.overstreet@linux.dev Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/bcachefs/fs-io.c | 2 +- fs/bcachefs/journal_io.c | 3 ++- 2 files changed, 3 insertions(+), 2 deletions(-)
--- a/fs/bcachefs/fs-io.c +++ b/fs/bcachefs/fs-io.c @@ -79,7 +79,7 @@ void bch2_inode_flush_nocow_writes_async continue;
bio = container_of(bio_alloc_bioset(ca->disk_sb.bdev, 0, - REQ_OP_FLUSH, + REQ_OP_WRITE|REQ_PREFLUSH, GFP_KERNEL, &c->nocow_flush_bioset), struct nocow_flush, bio); --- a/fs/bcachefs/journal_io.c +++ b/fs/bcachefs/journal_io.c @@ -1948,7 +1948,8 @@ CLOSURE_CALLBACK(bch2_journal_write) percpu_ref_get(&ca->io_ref);
bio = ca->journal.bio; - bio_reset(bio, ca->disk_sb.bdev, REQ_OP_FLUSH); + bio_reset(bio, ca->disk_sb.bdev, + REQ_OP_WRITE|REQ_PREFLUSH); bio->bi_end_io = journal_write_endio; bio->bi_private = ca; closure_bio_submit(bio, cl);