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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: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
This commit is contained in:
David Howells 2023-10-04 16:15:48 +01:00
parent 6ba22d8d15
commit 4fcccc38eb
3 changed files with 23 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
fs/netfs/buffered_read.c
View File

@ -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 @@ retry:
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);

28
fs/netfs/io.c
View File

@ -362,6 +362,7 @@ again:
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);
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))

9
include/trace/events/netfs.h
View File

@ -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 \