Commit 4fcccc38 authored by David Howells's avatar David Howells
Browse files

netfs: Make the refcounting of netfs_begin_read() easier to use 



Make the refcounting of netfs_begin_read() easier to use by not eating the
caller's ref on the netfs_io_request it's given.  This makes it easier to
use when we need to look in the request struct after.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
parent 6ba22d8d

fs/netfs/buffered_read.c

+5 −1
Original line number Diff line number Diff line
@@ -210,6 +210,7 @@ void netfs_readahead(struct readahead_control *ractl) 
		;



	netfs_begin_read(rreq, false);

	netfs_put_request(rreq, false, netfs_rreq_trace_put_return);

	return;



cleanup_free:
@@ -260,7 +261,9 @@ int netfs_read_folio(struct file *file, struct folio *folio) 
	iov_iter_xarray(&rreq->iter, ITER_DEST, &mapping->i_pages,

			rreq->start, rreq->len);



	return netfs_begin_read(rreq, true);

	ret = netfs_begin_read(rreq, true);

	netfs_put_request(rreq, false, netfs_rreq_trace_put_return);

	return ret;



discard:

	netfs_put_request(rreq, false, netfs_rreq_trace_put_discard);
@@ -429,6 +432,7 @@ int netfs_write_begin(struct netfs_inode *ctx, 
	ret = netfs_begin_read(rreq, true);

	if (ret < 0)

		goto error;

	netfs_put_request(rreq, false, netfs_rreq_trace_put_return);



have_folio:

	ret = folio_wait_fscache_killable(folio);

fs/netfs/io.c

+13 −15
Original line number Diff line number Diff line
@@ -362,6 +362,7 @@ static void netfs_rreq_assess(struct netfs_io_request *rreq, bool was_async) 


	netfs_rreq_unlock_folios(rreq);



	trace_netfs_rreq(rreq, netfs_rreq_trace_wake_ip);

	clear_bit_unlock(NETFS_RREQ_IN_PROGRESS, &rreq->flags);

	wake_up_bit(&rreq->flags, NETFS_RREQ_IN_PROGRESS);
@@ -657,7 +658,6 @@ int netfs_begin_read(struct netfs_io_request *rreq, bool sync) 


	if (rreq->len == 0) {

		pr_err("Zero-sized read [R=%x]\n", rreq->debug_id);

		netfs_put_request(rreq, false, netfs_rreq_trace_put_zero_len);

		return -EIO;

	}
@@ -665,12 +665,10 @@ int netfs_begin_read(struct netfs_io_request *rreq, bool sync) 


	INIT_WORK(&rreq->work, netfs_rreq_work);



	if (sync)

		netfs_get_request(rreq, netfs_rreq_trace_get_hold);



	/* Chop the read into slices according to what the cache and the netfs

	 * want and submit each one.

	 */

	netfs_get_request(rreq, netfs_rreq_trace_get_for_outstanding);

	atomic_set(&rreq->nr_outstanding, 1);

	io_iter = rreq->io_iter;

	do {
@@ -680,25 +678,25 @@ int netfs_begin_read(struct netfs_io_request *rreq, bool sync) 
	} while (rreq->submitted < rreq->len);



	if (sync) {

		/* Keep nr_outstanding incremented so that the ref always belongs to

		 * us, and the service code isn't punted off to a random thread pool to

		 * process.

		/* Keep nr_outstanding incremented so that the ref always

		 * belongs to us, and the service code isn't punted off to a

		 * random thread pool to process.  Note that this might start

		 * further work, such as writing to the cache.

		 */

		for (;;) {

		wait_var_event(&rreq->nr_outstanding,

			       atomic_read(&rreq->nr_outstanding) == 1);

		if (atomic_dec_and_test(&rreq->nr_outstanding))

			netfs_rreq_assess(rreq, false);

			if (!test_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags))

				break;

			cond_resched();

		}



		trace_netfs_rreq(rreq, netfs_rreq_trace_wait_ip);

		wait_on_bit(&rreq->flags, NETFS_RREQ_IN_PROGRESS,

			    TASK_UNINTERRUPTIBLE);



		ret = rreq->error;

		if (ret == 0 && rreq->submitted < rreq->len) {

			trace_netfs_failure(rreq, NULL, ret, netfs_fail_short_read);

			ret = -EIO;

		}

		netfs_put_request(rreq, false, netfs_rreq_trace_put_hold);

	} else {

		/* If we decrement nr_outstanding to 0, the ref belongs to us. */

		if (atomic_dec_and_test(&rreq->nr_outstanding))

include/trace/events/netfs.h

+5 −4
Original line number Diff line number Diff line
@@ -34,7 +34,9 @@ 
	EM(netfs_rreq_trace_free,		"FREE   ")	\

	EM(netfs_rreq_trace_resubmit,		"RESUBMT")	\

	EM(netfs_rreq_trace_unlock,		"UNLOCK ")	\

	E_(netfs_rreq_trace_unmark,		"UNMARK ")

	EM(netfs_rreq_trace_unmark,		"UNMARK ")	\

	EM(netfs_rreq_trace_wait_ip,		"WAIT-IP")	\

	E_(netfs_rreq_trace_wake_ip,		"WAKE-IP")



#define netfs_sreq_sources					\

	EM(NETFS_FILL_WITH_ZEROES,		"ZERO")		\
@@ -65,14 +67,13 @@ 
	E_(netfs_fail_prepare_write,		"prep-write")



#define netfs_rreq_ref_traces					\

	EM(netfs_rreq_trace_get_hold,		"GET HOLD   ")	\

	EM(netfs_rreq_trace_get_for_outstanding,"GET OUTSTND")	\

	EM(netfs_rreq_trace_get_subreq,		"GET SUBREQ ")	\

	EM(netfs_rreq_trace_put_complete,	"PUT COMPLT ")	\

	EM(netfs_rreq_trace_put_discard,	"PUT DISCARD")	\

	EM(netfs_rreq_trace_put_failed,		"PUT FAILED ")	\

	EM(netfs_rreq_trace_put_hold,		"PUT HOLD   ")	\

	EM(netfs_rreq_trace_put_return,		"PUT RETURN ")	\

	EM(netfs_rreq_trace_put_subreq,		"PUT SUBREQ ")	\

	EM(netfs_rreq_trace_put_zero_len,	"PUT ZEROLEN")	\

	E_(netfs_rreq_trace_new,		"NEW        ")



#define netfs_sreq_ref_traces					\