[PATCH 34/33] netfs: Pass flag rather than use in_softirq()

David Howells
2021-02-18T14:03:03Z

Christoph Hellwig <hch@lst.de> wrote:

> On Tue, Feb 16, 2021 at 09:29:31AM +0000, David Howells wrote:
> > Is there a better way to do it? The intent is to process the assessment
> > phase in the calling thread's context if possible rather than bumping over
> > to a worker thread. For synchronous I/O, for example, that's done in the
> > caller's thread. Maybe that's the answer - if it's known to be
> > asynchronous, I have to punt, but otherwise don't have to.
>
> Yes, i think you want an explicit flag instead.

How about the attached instead?

David
---
commit 29b3e9eed616db01f15c7998c062b4e501ea6582
Author: David Howells <dhowells@redhat.com>
Date: Mon Feb 15 21:56:43 2021 +0000

netfs: Pass flag rather than use in_softirq()

The in_softirq() in netfs_rreq_terminated() works fine for the cache being
on a normal disk, as the completion handlers may get called in softirq
context, but for an NVMe drive, the completion handler may get called in
IRQ context.

Fix to pass a flag to netfs_subreq_terminated() to indicate whether we
think the function isn't being called from a context in which we can do
allocations, waits and I/O submissions (such as softirq or interrupt
context). If this flag is set, netfs lib has to punt to a worker thread to
handle anything like that.

The symptom involves warnings like the following appearing and the kernel
hanging:

WARNING: CPU: 0 PID: 0 at kernel/softirq.c:175 __local_bh_enable_ip+0x35/0x50
...
RIP: 0010:__local_bh_enable_ip+0x35/0x50
...
Call Trace:
<IRQ>
rxrpc_kernel_begin_call+0x7d/0x1b0 [rxrpc]
? afs_rx_new_call+0x40/0x40 [kafs]
? afs_alloc_call+0x28/0x120 [kafs]
afs_make_call+0x120/0x510 [kafs]
? afs_rx_new_call+0x40/0x40 [kafs]
? afs_alloc_flat_call+0xba/0x100 [kafs]
? __kmalloc+0x167/0x2f0
? afs_alloc_flat_call+0x9b/0x100 [kafs]
afs_wait_for_operation+0x2d/0x200 [kafs]
afs_do_sync_operation+0x16/0x20 [kafs]
afs_req_issue_op+0x8c/0xb0 [kafs]
netfs_rreq_assess+0x125/0x7d0 [netfs]
? cachefiles_end_operation+0x40/0x40 [cachefiles]
netfs_subreq_terminated+0x117/0x220 [netfs]
cachefiles_read_complete+0x21/0x60 [cachefiles]
iomap_dio_bio_end_io+0xdd/0x110
blk_update_request+0x20a/0x380
blk_mq_end_request+0x1c/0x120
nvme_process_cq+0x159/0x1f0 [nvme]
nvme_irq+0x10/0x20 [nvme]
__handle_irq_event_percpu+0x37/0x150
handle_irq_event+0x49/0xb0
handle_edge_irq+0x7c/0x200
asm_call_irq_on_stack+0xf/0x20
</IRQ>
common_interrupt+0xad/0x120
asm_common_interrupt+0x1e/0x40
...

Reported-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Matthew Wilcox <willy@infradead.org>
cc: linux-mm@kvack.org
cc: linux-cachefs@redhat.com
cc: linux-afs@lists.infradead.org
cc: linux-nfs@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: ceph-devel@vger.kernel.org
cc: v9fs-developer@lists.sourceforge.net
cc: linux-fsdevel@vger.kernel.org

diff --git a/fs/afs/file.c b/fs/afs/file.c
index 8f28d4f4cfd7..6dcdbbfb48e2 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -223,7 +223,7 @@ static void afs_fetch_data_notify(struct afs_operation *op)

if (subreq) {
__set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
- netfs_subreq_terminated(subreq, error ?: req->actual_len);
+ netfs_subreq_terminated(subreq, error ?: req->actual_len, false);
req->subreq = NULL;
} else if (req->done) {
req->done(req);
@@ -289,7 +289,7 @@ static void afs_req_issue_op(struct netfs_read_subrequest *subreq)

fsreq = afs_alloc_read(GFP_NOFS);
if (!fsreq)
- return netfs_subreq_terminated(subreq, -ENOMEM);
+ return netfs_subreq_terminated(subreq, -ENOMEM, false);

fsreq->subreq = subreq;
fsreq->pos = subreq->start + subreq->transferred;
@@ -304,7 +304,7 @@ static void afs_req_issue_op(struct netfs_read_subrequest *subreq)

ret = afs_fetch_data(fsreq->vnode, fsreq);
if (ret < 0)
- return netfs_subreq_terminated(subreq, ret);
+ return netfs_subreq_terminated(subreq, ret, false);
}

static int afs_symlink_readpage(struct page *page)
diff --git a/fs/cachefiles/rdwr2.c b/fs/cachefiles/rdwr2.c
index 4cea5a2a2d6e..40668bfe6688 100644
--- a/fs/cachefiles/rdwr2.c
+++ b/fs/cachefiles/rdwr2.c
@@ -23,6 +23,7 @@ struct cachefiles_kiocb {
};
netfs_io_terminated_t term_func;
void *term_func_priv;
+ bool was_async;
};

static inline void cachefiles_put_kiocb(struct cachefiles_kiocb *ki)
@@ -43,10 +44,9 @@ static void cachefiles_read_complete(struct kiocb *iocb, long ret, long ret2)
_enter("%ld,%ld", ret, ret2);

if (ki->term_func) {
- if (ret < 0)
- ki->term_func(ki->term_func_priv, ret);
- else
- ki->term_func(ki->term_func_priv, ki->skipped + ret);
+ if (ret >= 0)
+ ret += ki->skipped;
+ ki->term_func(ki->term_func_priv, ret, ki->was_async);
}

cachefiles_put_kiocb(ki);
@@ -114,6 +114,7 @@ static int cachefiles_read(struct netfs_cache_resources *cres,
ki->skipped = skipped;
ki->term_func = term_func;
ki->term_func_priv = term_func_priv;
+ ki->was_async = true;

if (ki->term_func)
ki->iocb.ki_complete = cachefiles_read_complete;
@@ -141,6 +142,7 @@ static int cachefiles_read(struct netfs_cache_resources *cres,
ret = -EINTR;
fallthrough;
default:
+ ki->was_async = false;
cachefiles_read_complete(&ki->iocb, ret, 0);
if (ret > 0)
ret = 0;
@@ -156,7 +158,7 @@ static int cachefiles_read(struct netfs_cache_resources *cres,
kfree(ki);
presubmission_error:
if (term_func)
- term_func(term_func_priv, ret < 0 ? ret : skipped);
+ term_func(term_func_priv, ret < 0 ? ret : skipped, false);
return ret;
}

@@ -175,7 +177,7 @@ static void cachefiles_write_complete(struct kiocb *iocb, long ret, long ret2)
__sb_end_write(inode->i_sb, SB_FREEZE_WRITE);

if (ki->term_func)
- ki->term_func(ki->term_func_priv, ret);
+ ki->term_func(ki->term_func_priv, ret, ki->was_async);

cachefiles_put_kiocb(ki);
}
@@ -214,6 +216,7 @@ static int cachefiles_write(struct netfs_cache_resources *cres,
ki->len = len;
ki->term_func = term_func;
ki->term_func_priv = term_func_priv;
+ ki->was_async = true;

if (ki->term_func)
ki->iocb.ki_complete = cachefiles_write_complete;
@@ -250,6 +253,7 @@ static int cachefiles_write(struct netfs_cache_resources *cres,
ret = -EINTR;
/* Fall through */
default:
+ ki->was_async = false;
cachefiles_write_complete(&ki->iocb, ret, 0);
if (ret > 0)
ret = 0;
@@ -265,7 +269,7 @@ static int cachefiles_write(struct netfs_cache_resources *cres,
kfree(ki);
presubmission_error:
if (term_func)
- term_func(term_func_priv, -ENOMEM);
+ term_func(term_func_priv, -ENOMEM, false);
return -ENOMEM;
}

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 0dd64d31eff6..dcfd805d168e 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -221,7 +221,7 @@ static void finish_netfs_read(struct ceph_osd_request *req)
if (err >= 0 && err < subreq->len)
__set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);

- netfs_subreq_terminated(subreq, err);
+ netfs_subreq_terminated(subreq, err, true);

num_pages = calc_pages_for(osd_data->alignment, osd_data->length);
ceph_put_page_vector(osd_data->pages, num_pages, false);
@@ -276,7 +276,7 @@ static void ceph_netfs_issue_op(struct netfs_read_subrequest *subreq)
out:
ceph_osdc_put_request(req);
if (err)
- netfs_subreq_terminated(subreq, err);
+ netfs_subreq_terminated(subreq, err, false);
dout("%s: result %d\n", __func__, err);
}

diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c
index 9191a3617d91..5f5de8278499 100644
--- a/fs/netfs/read_helper.c
+++ b/fs/netfs/read_helper.c
@@ -29,12 +29,13 @@ module_param_named(debug, netfs_debug, uint, S_IWUSR | S_IRUGO);
MODULE_PARM_DESC(netfs_debug, "Netfs support debugging mask");

static void netfs_rreq_work(struct work_struct *);
-static void __netfs_put_subrequest(struct netfs_read_subrequest *);
+static void __netfs_put_subrequest(struct netfs_read_subrequest *, bool);

-static void netfs_put_subrequest(struct netfs_read_subrequest *subreq)
+static void netfs_put_subrequest(struct netfs_read_subrequest *subreq,
+ bool was_async)
{
if (refcount_dec_and_test(&subreq->usage))
- __netfs_put_subrequest(subreq);
+ __netfs_put_subrequest(subreq, was_async);
}

static struct netfs_read_request *netfs_alloc_read_request(
@@ -67,7 +68,8 @@ static void netfs_get_read_request(struct netfs_read_request *rreq)
refcount_inc(&rreq->usage);
}

-static void netfs_rreq_clear_subreqs(struct netfs_read_request *rreq)
+static void netfs_rreq_clear_subreqs(struct netfs_read_request *rreq,
+ bool was_async)
{
struct netfs_read_subrequest *subreq;

@@ -75,7 +77,7 @@ static void netfs_rreq_clear_subreqs(struct netfs_read_request *rreq)
subreq = list_first_entry(&rreq->subrequests,
struct netfs_read_subrequest, rreq_link);
list_del(&subreq->rreq_link);
- netfs_put_subrequest(subreq);
+ netfs_put_subrequest(subreq, was_async);
}
}

@@ -83,7 +85,7 @@ static void netfs_free_read_request(struct work_struct *work)
{
struct netfs_read_request *rreq =
container_of(work, struct netfs_read_request, work);
- netfs_rreq_clear_subreqs(rreq);
+ netfs_rreq_clear_subreqs(rreq, false);
if (rreq->netfs_priv)
rreq->netfs_ops->cleanup(rreq->mapping, rreq->netfs_priv);
trace_netfs_rreq(rreq, netfs_rreq_trace_free);
@@ -93,10 +95,10 @@ static void netfs_free_read_request(struct work_struct *work)
netfs_stat_d(&netfs_n_rh_rreq);
}

-static void netfs_put_read_request(struct netfs_read_request *rreq)
+static void netfs_put_read_request(struct netfs_read_request *rreq, bool was_async)
{
if (refcount_dec_and_test(&rreq->usage)) {
- if (in_softirq()) {
+ if (was_async) {
rreq->work.func = netfs_free_read_request;
if (!queue_work(system_unbound_wq, &rreq->work))
BUG();
@@ -131,12 +133,15 @@ static void netfs_get_read_subrequest(struct netfs_read_subrequest *subreq)
refcount_inc(&subreq->usage);
}

-static void __netfs_put_subrequest(struct netfs_read_subrequest *subreq)
+static void __netfs_put_subrequest(struct netfs_read_subrequest *subreq,
+ bool was_async)
{
+ struct netfs_read_request *rreq = subreq->rreq;
+
trace_netfs_sreq(subreq, netfs_sreq_trace_free);
- netfs_put_read_request(subreq->rreq);
kfree(subreq);
netfs_stat_d(&netfs_n_rh_sreq);
+ netfs_put_read_request(rreq, was_async);
}

/*
@@ -152,11 +157,12 @@ static void netfs_clear_unread(struct netfs_read_subrequest *subreq)
iov_iter_zero(iov_iter_count(&iter), &iter);
}

-static void netfs_cache_read_terminated(void *priv, ssize_t transferred_or_error)
+static void netfs_cache_read_terminated(void *priv, ssize_t transferred_or_error,
+ bool was_async)
{
struct netfs_read_subrequest *subreq = priv;

- netfs_subreq_terminated(subreq, transferred_or_error);
+ netfs_subreq_terminated(subreq, transferred_or_error, was_async);
}

/*
@@ -186,7 +192,7 @@ static void netfs_fill_with_zeroes(struct netfs_read_request *rreq,
{
netfs_stat(&netfs_n_rh_zero);
__set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
- netfs_subreq_terminated(subreq, 0);
+ netfs_subreq_terminated(subreq, 0, false);
}

/*
@@ -215,11 +221,11 @@ static void netfs_read_from_server(struct netfs_read_request *rreq,
/*
* Release those waiting.
*/
-static void netfs_rreq_completed(struct netfs_read_request *rreq)
+static void netfs_rreq_completed(struct netfs_read_request *rreq, bool was_async)
{
trace_netfs_rreq(rreq, netfs_rreq_trace_done);
- netfs_rreq_clear_subreqs(rreq);
- netfs_put_read_request(rreq);
+ netfs_rreq_clear_subreqs(rreq, was_async);
+ netfs_put_read_request(rreq, was_async);
}

/*
@@ -228,7 +234,8 @@ static void netfs_rreq_completed(struct netfs_read_request *rreq)
*
* May be called in softirq mode and we inherit a ref from the caller.
*/
-static void netfs_rreq_unmark_after_write(struct netfs_read_request *rreq)
+static void netfs_rreq_unmark_after_write(struct netfs_read_request *rreq,
+ bool was_async)
{
struct netfs_read_subrequest *subreq;
struct pagevec pvec;
@@ -258,10 +265,11 @@ static void netfs_rreq_unmark_after_write(struct netfs_read_request *rreq)
}

rcu_read_unlock();
- netfs_rreq_completed(rreq);
+ netfs_rreq_completed(rreq, was_async);
}

-static void netfs_rreq_copy_terminated(void *priv, ssize_t transferred_or_error)
+static void netfs_rreq_copy_terminated(void *priv, ssize_t transferred_or_error,
+ bool was_async)
{
struct netfs_read_subrequest *subreq = priv;
struct netfs_read_request *rreq = subreq->rreq;
@@ -278,9 +286,9 @@ static void netfs_rreq_copy_terminated(void *priv, ssize_t transferred_or_error)

/* If we decrement nr_wr_ops to 0, the ref belongs to us. */
if (atomic_dec_and_test(&rreq->nr_wr_ops))
- netfs_rreq_unmark_after_write(rreq);
+ netfs_rreq_unmark_after_write(rreq, was_async);

- netfs_put_subrequest(subreq);
+ netfs_put_subrequest(subreq, was_async);
}

/*
@@ -304,7 +312,7 @@ static void netfs_rreq_do_write_to_cache(struct netfs_read_request *rreq)
list_for_each_entry_safe(subreq, p, &rreq->subrequests, rreq_link) {
if (!test_bit(NETFS_SREQ_WRITE_TO_CACHE, &subreq->flags)) {
list_del_init(&subreq->rreq_link);
- netfs_put_subrequest(subreq);
+ netfs_put_subrequest(subreq, false);
}
}

@@ -324,7 +332,7 @@ static void netfs_rreq_do_write_to_cache(struct netfs_read_request *rreq)
subreq->len += next->len;
subreq->len = round_up(subreq->len, PAGE_SIZE);
list_del_init(&next->rreq_link);
- netfs_put_subrequest(next);
+ netfs_put_subrequest(next, false);
}

iov_iter_xarray(&iter, WRITE, &rreq->mapping->i_pages,
@@ -340,7 +348,7 @@ static void netfs_rreq_do_write_to_cache(struct netfs_read_request *rreq)

/* If we decrement nr_wr_ops to 0, the usage ref belongs to us. */
if (atomic_dec_and_test(&rreq->nr_wr_ops))
- netfs_rreq_unmark_after_write(rreq);
+ netfs_rreq_unmark_after_write(rreq, false);
}

static void netfs_rreq_write_to_cache_work(struct work_struct *work)
@@ -351,9 +359,10 @@ static void netfs_rreq_write_to_cache_work(struct work_struct *work)
netfs_rreq_do_write_to_cache(rreq);
}

-static void netfs_rreq_write_to_cache(struct netfs_read_request *rreq)
+static void netfs_rreq_write_to_cache(struct netfs_read_request *rreq,
+ bool was_async)
{
- if (in_softirq()) {
+ if (was_async) {
rreq->work.func = netfs_rreq_write_to_cache_work;
if (!queue_work(system_unbound_wq, &rreq->work))
BUG();
@@ -479,7 +488,7 @@ static bool netfs_rreq_perform_resubmissions(struct netfs_read_request *rreq)
{
struct netfs_read_subrequest *subreq;

- WARN_ON(in_softirq());
+ WARN_ON(in_interrupt());

trace_netfs_rreq(rreq, netfs_rreq_trace_resubmit);

@@ -538,7 +547,7 @@ static void netfs_rreq_is_still_valid(struct netfs_read_request *rreq)
* Note that we could be in an ordinary kernel thread, on a workqueue or in
* softirq context at this point. We inherit a ref from the caller.
*/
-static void netfs_rreq_assess(struct netfs_read_request *rreq)
+static void netfs_rreq_assess(struct netfs_read_request *rreq, bool was_async)
{
trace_netfs_rreq(rreq, netfs_rreq_trace_assess);

@@ -558,30 +567,31 @@ static void netfs_rreq_assess(struct netfs_read_request *rreq)
wake_up_bit(&rreq->flags, NETFS_RREQ_IN_PROGRESS);

if (test_bit(NETFS_RREQ_WRITE_TO_CACHE, &rreq->flags))
- return netfs_rreq_write_to_cache(rreq);
+ return netfs_rreq_write_to_cache(rreq, was_async);

- netfs_rreq_completed(rreq);
+ netfs_rreq_completed(rreq, was_async);
}

static void netfs_rreq_work(struct work_struct *work)
{
struct netfs_read_request *rreq =
container_of(work, struct netfs_read_request, work);
- netfs_rreq_assess(rreq);
+ netfs_rreq_assess(rreq, false);
}

/*
* Handle the completion of all outstanding I/O operations on a read request.
* We inherit a ref from the caller.
*/
-static void netfs_rreq_terminated(struct netfs_read_request *rreq)
+static void netfs_rreq_terminated(struct netfs_read_request *rreq,
+ bool was_async)
{
if (test_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags) &&
- in_softirq()) {
+ was_async) {
if (!queue_work(system_unbound_wq, &rreq->work))
BUG();
} else {
- netfs_rreq_assess(rreq);
+ netfs_rreq_assess(rreq, was_async);
}
}

@@ -589,6 +599,7 @@ static void netfs_rreq_terminated(struct netfs_read_request *rreq)
* netfs_subreq_terminated - Note the termination of an I/O operation.
* @subreq: The I/O request that has terminated.
* @transferred_or_error: The amount of data transferred or an error code.
+ * @was_async: The termination was asynchronous
*
* This tells the read helper that a contributory I/O operation has terminated,
* one way or another, and that it should integrate the results.
@@ -599,11 +610,12 @@ static void netfs_rreq_terminated(struct netfs_read_request *rreq)
* error code. The helper will look after reissuing I/O operations as
* appropriate and writing downloaded data to the cache.
*
- * This may be called from a softirq handler, so we want to avoid taking the
- * spinlock if we can.
+ * If @was_async is true, the caller might be running in softirq or interrupt
+ * context and we can't sleep.
*/
void netfs_subreq_terminated(struct netfs_read_subrequest *subreq,
- ssize_t transferred_or_error)
+ ssize_t transferred_or_error,
+ bool was_async)
{
struct netfs_read_request *rreq = subreq->rreq;
int u;
@@ -647,11 +659,11 @@ void netfs_subreq_terminated(struct netfs_read_subrequest *subreq,
/* If we decrement nr_rd_ops to 0, the ref belongs to us. */
u = atomic_dec_return(&rreq->nr_rd_ops);
if (u == 0)
- netfs_rreq_terminated(rreq);
+ netfs_rreq_terminated(rreq, was_async);
else if (u == 1)
wake_up_var(&rreq->nr_rd_ops);

- netfs_put_subrequest(subreq);
+ netfs_put_subrequest(subreq, was_async);
return;

incomplete:
@@ -796,7 +808,7 @@ static bool netfs_rreq_submit_slice(struct netfs_read_request *rreq,

subreq_failed:
rreq->error = subreq->error;
- netfs_put_subrequest(subreq);
+ netfs_put_subrequest(subreq, false);
return false;
}

@@ -901,7 +913,7 @@ void netfs_readahead(struct readahead_control *ractl,
} while (rreq->submitted < rreq->len);

if (rreq->submitted == 0) {
- netfs_put_read_request(rreq);
+ netfs_put_read_request(rreq, false);
return;
}

@@ -913,11 +925,11 @@ void netfs_readahead(struct readahead_control *ractl,

/* If we decrement nr_rd_ops to 0, the ref belongs to us. */
if (atomic_dec_and_test(&rreq->nr_rd_ops))
- netfs_rreq_assess(rreq);
+ netfs_rreq_assess(rreq, false);
return;

cleanup_free:
- netfs_put_read_request(rreq);
+ netfs_put_read_request(rreq, false);
return;
cleanup:
if (netfs_priv)
@@ -991,14 +1003,14 @@ int netfs_readpage(struct file *file,
*/
do {
wait_var_event(&rreq->nr_rd_ops, atomic_read(&rreq->nr_rd_ops) == 1);
- netfs_rreq_assess(rreq);
+ netfs_rreq_assess(rreq, false);
} while (test_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags));

ret = rreq->error;
if (ret == 0 && rreq->submitted < rreq->len)
ret = -EIO;
out:
- netfs_put_read_request(rreq);
+ netfs_put_read_request(rreq, false);
return ret;
}
EXPORT_SYMBOL(netfs_readpage);
@@ -1136,7 +1148,7 @@ int netfs_write_begin(struct file *file, struct address_space *mapping,
*/
for (;;) {
wait_var_event(&rreq->nr_rd_ops, atomic_read(&rreq->nr_rd_ops) == 1);
- netfs_rreq_assess(rreq);
+ netfs_rreq_assess(rreq, false);
if (!test_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags))
break;
cond_resched();
@@ -1145,7 +1157,7 @@ int netfs_write_begin(struct file *file, struct address_space *mapping,
ret = rreq->error;
if (ret == 0 && rreq->submitted < rreq->len)
ret = -EIO;
- netfs_put_read_request(rreq);
+ netfs_put_read_request(rreq, false);
if (ret < 0)
goto error;

diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index b2589b39feb8..c22b64db237d 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -60,7 +60,8 @@ enum netfs_read_source {
NETFS_INVALID_READ,
} __mode(byte);

-typedef void (*netfs_io_terminated_t)(void *priv, ssize_t transferred_or_error);
+typedef void (*netfs_io_terminated_t)(void *priv, ssize_t transferred_or_error,
+ bool was_async);

/*
* Resources required to do operations on a cache.
@@ -189,7 +190,7 @@ extern int netfs_write_begin(struct file *, struct address_space *,
const struct netfs_read_request_ops *,
void *);

-extern void netfs_subreq_terminated(struct netfs_read_subrequest *, ssize_t);
+extern void netfs_subreq_terminated(struct netfs_read_subrequest *, ssize_t, bool);
extern void netfs_stats_show(struct seq_file *);

#endif /* _LINUX_NETFS_H */