Remove test_generic_01.sh since block layer may reorder I/O, making
the test prone to false positives. Apply the improvements to
test_generic_02.sh instead, which supposes for covering ublk dispatch
io order.
Rework test_generic_02 to verify that ublk dispatch doesn't reorder I/O
by comparing request start order with completion order using bpftrace.
The bpftrace script now:
- Tracks each request's start sequence number in a map keyed by sector
- On completion, verifies the request's start order matches expected
completion order
- Reports any out-of-order completions detected
The test script:
- Wait bpftrace BEGIN code block is run
- Pins fio to CPU 0 for deterministic behavior
- Uses block_io_start and block_rq_complete tracepoints
- Checks bpftrace output for reordering errors
Reported-and-tested-by: Alexander Atanasov <alex@zazolabs.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The last_rw map is initialized with a value of 0 but later assigned the
value args.sector + args.nr_sector, which has type sector_t = u64.
bpftrace complains about the type mismatch between int64 and uint64:
trace/seq_io.bt:18:3-59: ERROR: Type mismatch for @last_rw: trying to assign value of type 'uint64' when map already contains a value of type 'int64'
@last_rw[$dev, str($2)] = (args.sector + args.nr_sector);
Cast the initial value to uint64 so bpftrace will load the program.
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
block layer, ublk and io_uring might re-order IO in the past
- plug
- queue ublk io command via task work
Add one test for verifying if sequential WRITE IO is dispatched in order.
- null target is taken, so we can just observe io order from
`tracepoint:block:block_rq_complete` which represents the dispatch order
- WRITE IO is taken because READ may come from system-wide utility
Cc: Uday Shankar <ushankar@purestorage.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250322093218.431419-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
