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blktrace: split out relaying a blktrace event

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Split out the code relaying a blktrace event to user-space using relayfs.

This enables adding a second version supporting a new version of the
protocol.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Johannes Thumshirn 2025-10-22 13:41:02 +02:00 • committed by Jens Axboe
parent 472eca5383
commit 04678e72e9
1 changed files with 32 additions and 28 deletions
Download patch file Download diff file Expand all files Collapse all files

60
kernel/trace/blktrace.c
View file

@ -91,6 +91,26 @@ static void record_blktrace_event(struct blk_io_trace *t, pid_t pid, int cpu,
memcpy((void *)t + sizeof(*t) + cgid_len, pdu_data, pdu_len);
}
static void relay_blktrace_event(struct blk_trace *bt, unsigned long sequence,
pid_t pid, int cpu, sector_t sector, int bytes,
u32 what, int error, u64 cgid,
ssize_t cgid_len, void *pdu_data, int pdu_len)
{
struct blk_io_trace *t;
size_t trace_len = sizeof(*t) + pdu_len + cgid_len;
t = relay_reserve(bt->rchan, trace_len);
if (!t)
return;
t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
t->sequence = sequence;
t->time = ktime_to_ns(ktime_get());
record_blktrace_event(t, pid, cpu, sector, bytes, what, bt->dev, error,
cgid, cgid_len, pdu_data, pdu_len);
}
/*
* Send out a notify message.
*/
@ -126,16 +146,9 @@ static void trace_note(struct blk_trace *bt, pid_t pid, int action,
if (!bt->rchan)
return;
t = relay_reserve(bt->rchan, trace_len);
if (t) {
t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
t->time = ktime_to_ns(ktime_get());
record_blktrace_event(t, pid, cpu, 0, 0,
action | (cgid ? __BLK_TN_CGROUP : 0),
bt->dev, 0, cgid, cgid_len, (void *)data,
len);
}
relay_blktrace_event(bt, 0, pid, cpu, 0, 0,
action | (cgid ? __BLK_TN_CGROUP : 0), 0, cgid,
cgid_len, (void *)data, len);
}
/*
@ -246,7 +259,6 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
struct task_struct *tsk = current;
struct ring_buffer_event *event = NULL;
struct trace_buffer *buffer = NULL;
struct blk_io_trace *t;
unsigned long flags = 0;
unsigned long *sequence;
unsigned int trace_ctx = 0;
@ -278,20 +290,21 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
return;
cpu = raw_smp_processor_id();
trace_len = sizeof(*t) + pdu_len + cgid_len;
if (blk_tracer) {
tracing_record_cmdline(current);
buffer = blk_tr->array_buffer.buffer;
trace_ctx = tracing_gen_ctx_flags(0);
trace_len = sizeof(struct blk_io_trace) + pdu_len + cgid_len;
event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
trace_len, trace_ctx);
if (!event)
return;
t = ring_buffer_event_data(event);
record_blktrace_event(t, pid, cpu, sector, bytes, what, bt->dev,
error, cgid, cgid_len, pdu_data, pdu_len);
record_blktrace_event(ring_buffer_event_data(event),
pid, cpu, sector, bytes, what, bt->dev,
error, cgid, cgid_len, pdu_data,
pdu_len);
trace_buffer_unlock_commit(blk_tr, buffer, event, trace_ctx);
return;
@ -306,19 +319,10 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
* from coming in and stepping on our toes.
*/
local_irq_save(flags);
t = relay_reserve(bt->rchan, trace_len);
if (t) {
sequence = per_cpu_ptr(bt->sequence, cpu);
t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
t->sequence = ++(*sequence);
t->time = ktime_to_ns(ktime_get());
record_blktrace_event(t, pid, cpu, sector, bytes, what,
bt->dev, error, cgid, cgid_len,
pdu_data, pdu_len);
}
sequence = per_cpu_ptr(bt->sequence, cpu);
(*sequence)++;
relay_blktrace_event(bt, *sequence, pid, cpu, sector, bytes, what,
error, cgid, cgid_len, pdu_data, pdu_len);
local_irq_restore(flags);
}