[PATCH 6.12 009/189] netfs: Fix enomem handling in buffered reads

[PATCH 6.12 009/189] netfs: Fix enomem handling in buffered reads

[Greg Kroah-Hartman]

6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Howells <dhowells@redhat.com>

[ Upstream commit 105549d09a539a876b7c3330ab52d8aceedad358 ]

If netfs_read_to_pagecache() gets an error from either ->prepare_read() or
from netfs_prepare_read_iterator(), it needs to decrement ->nr_outstanding,
cancel the subrequest and break out of the issuing loop.  Currently, it
only does this for two of the cases, but there are two more that aren't
handled.

Fix this by moving the handling to a common place and jumping to it from
all four places.  This is in preference to inserting a wrapper around
netfs_prepare_read_iterator() as proposed by Dmitry Antipov[1].

Link: https://lore.kernel.org/r/20241202093943.227786-1-dmantipov@yandex.ru/ [1]

Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading")
Reported-by: syzbot+404b4b745080b6210c6c@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=404b4b745080b6210c6c
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20241213135013.2964079-4-dhowells@redhat.com
Tested-by: syzbot+404b4b745080b6210c6c@syzkaller.appspotmail.com
cc: Dmitry Antipov <dmantipov@yandex.ru>
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/netfs/buffered_read.c | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/fs/netfs/buffered_read.c b/fs/netfs/buffered_read.c
index af46a598f4d7..2dd2260352db 100644
--- a/fs/netfs/buffered_read.c
+++ b/fs/netfs/buffered_read.c
@@ -275,22 +275,14 @@ static void netfs_read_to_pagecache(struct netfs_io_request *rreq)
 			netfs_stat(&netfs_n_rh_download);
 			if (rreq->netfs_ops->prepare_read) {
 				ret = rreq->netfs_ops->prepare_read(subreq);
-				if (ret < 0) {
-					atomic_dec(&rreq->nr_outstanding);
-					netfs_put_subrequest(subreq, false,
-							     netfs_sreq_trace_put_cancel);
-					break;
-				}
+				if (ret < 0)
+					goto prep_failed;
 				trace_netfs_sreq(subreq, netfs_sreq_trace_prepare);
 			}
 
 			slice = netfs_prepare_read_iterator(subreq);
-			if (slice < 0) {
-				atomic_dec(&rreq->nr_outstanding);
-				netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_cancel);
-				ret = slice;
-				break;
-			}
+			if (slice < 0)
+				goto prep_iter_failed;
 
 			rreq->netfs_ops->issue_read(subreq);
 			goto done;
@@ -302,6 +294,8 @@ static void netfs_read_to_pagecache(struct netfs_io_request *rreq)
 			trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
 			netfs_stat(&netfs_n_rh_zero);
 			slice = netfs_prepare_read_iterator(subreq);
+			if (slice < 0)
+				goto prep_iter_failed;
 			__set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
 			netfs_read_subreq_terminated(subreq, 0, false);
 			goto done;
@@ -310,6 +304,8 @@ static void netfs_read_to_pagecache(struct netfs_io_request *rreq)
 		if (source == NETFS_READ_FROM_CACHE) {
 			trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
 			slice = netfs_prepare_read_iterator(subreq);
+			if (slice < 0)
+				goto prep_iter_failed;
 			netfs_read_cache_to_pagecache(rreq, subreq);
 			goto done;
 		}
@@ -318,6 +314,14 @@ static void netfs_read_to_pagecache(struct netfs_io_request *rreq)
 		WARN_ON_ONCE(1);
 		break;
 
+	prep_iter_failed:
+		ret = slice;
+	prep_failed:
+		subreq->error = ret;
+		atomic_dec(&rreq->nr_outstanding);
+		netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_cancel);
+		break;
+
 	done:
 		size -= slice;
 		start += slice;
-- 
2.39.5

[PATCH 6.12 010/189] nfs: Fix oops in nfs_netfs_init_request() when copying to cache

[Greg Kroah-Hartman]

6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Howells <dhowells@redhat.com>

[ Upstream commit 86ad1a58f6a9453f49e06ef957a40a8dac00a13f ]

When netfslib wants to copy some data that has just been read on behalf of
nfs, it creates a new write request and calls nfs_netfs_init_request() to
initialise it, but with a NULL file pointer.  This causes
nfs_file_open_context() to oops - however, we don't actually need the nfs
context as we're only going to write to the cache.

Fix this by just returning if we aren't given a file pointer and emit a
warning if the request was for something other than copy-to-cache.

Further, fix nfs_netfs_free_request() so that it doesn't try to free the
context if the pointer is NULL.

Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading")
Reported-by: Max Kellermann <max.kellermann@ionos.com>
Closes: https://lore.kernel.org/r/CAKPOu+9DyMbKLhyJb7aMLDTb=Fh0T8Teb9sjuf_pze+XWT1VaQ@mail.gmail.com/
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20241213135013.2964079-5-dhowells@redhat.com
cc: Trond Myklebust <trondmy@kernel.org>
cc: Anna Schumaker <anna@kernel.org>
cc: Dave Wysochanski <dwysocha@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-nfs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/nfs/fscache.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
index 810269ee0a50..d49e4ce27999 100644
--- a/fs/nfs/fscache.c
+++ b/fs/nfs/fscache.c
@@ -263,6 +263,12 @@ int nfs_netfs_readahead(struct readahead_control *ractl)
 static atomic_t nfs_netfs_debug_id;
 static int nfs_netfs_init_request(struct netfs_io_request *rreq, struct file *file)
 {
+	if (!file) {
+		if (WARN_ON_ONCE(rreq->origin != NETFS_PGPRIV2_COPY_TO_CACHE))
+			return -EIO;
+		return 0;
+	}
+
 	rreq->netfs_priv = get_nfs_open_context(nfs_file_open_context(file));
 	rreq->debug_id = atomic_inc_return(&nfs_netfs_debug_id);
 	/* [DEPRECATED] Use PG_private_2 to mark folio being written to the cache. */
@@ -274,7 +280,8 @@ static int nfs_netfs_init_request(struct netfs_io_request *rreq, struct file *fi
 
 static void nfs_netfs_free_request(struct netfs_io_request *rreq)
 {
-	put_nfs_open_context(rreq->netfs_priv);
+	if (rreq->netfs_priv)
+		put_nfs_open_context(rreq->netfs_priv);
 }
 
 static struct nfs_netfs_io_data *nfs_netfs_alloc(struct netfs_io_subrequest *sreq)
-- 
2.39.5

[PATCH 6.12 011/189] netfs: Fix missing barriers by using clear_and_wake_up_bit()

[Greg Kroah-Hartman]

6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Howells <dhowells@redhat.com>

[ Upstream commit aa3956418985bda1f68313eadde3267921847978 ]

Use clear_and_wake_up_bit() rather than something like:

	clear_bit_unlock(NETFS_RREQ_IN_PROGRESS, &rreq->flags);
	wake_up_bit(&rreq->flags, NETFS_RREQ_IN_PROGRESS);

as there needs to be a barrier inserted between which is present in
clear_and_wake_up_bit().

Fixes: 288ace2f57c9 ("netfs: New writeback implementation")
Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading")
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20241213135013.2964079-8-dhowells@redhat.com
Reviewed-by: Akira Yokosawa <akiyks@gmail.com>
cc: Zilin Guan <zilin@seu.edu.cn>
cc: Akira Yokosawa <akiyks@gmail.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/netfs/read_collect.c  | 3 +--
 fs/netfs/write_collect.c | 9 +++------
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/fs/netfs/read_collect.c b/fs/netfs/read_collect.c
index 3cbb289535a8..d86fa02f68fb 100644
--- a/fs/netfs/read_collect.c
+++ b/fs/netfs/read_collect.c
@@ -378,8 +378,7 @@ static void netfs_rreq_assess(struct netfs_io_request *rreq)
 	task_io_account_read(rreq->transferred);
 
 	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);
+	clear_and_wake_up_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags);
 
 	trace_netfs_rreq(rreq, netfs_rreq_trace_done);
 	netfs_clear_subrequests(rreq, false);
diff --git a/fs/netfs/write_collect.c b/fs/netfs/write_collect.c
index 1d438be2e1b4..82290c92ba7a 100644
--- a/fs/netfs/write_collect.c
+++ b/fs/netfs/write_collect.c
@@ -501,8 +501,7 @@ static void netfs_collect_write_results(struct netfs_io_request *wreq)
 		goto need_retry;
 	if ((notes & MADE_PROGRESS) && test_bit(NETFS_RREQ_PAUSE, &wreq->flags)) {
 		trace_netfs_rreq(wreq, netfs_rreq_trace_unpause);
-		clear_bit_unlock(NETFS_RREQ_PAUSE, &wreq->flags);
-		wake_up_bit(&wreq->flags, NETFS_RREQ_PAUSE);
+		clear_and_wake_up_bit(NETFS_RREQ_PAUSE, &wreq->flags);
 	}
 
 	if (notes & NEED_REASSESS) {
@@ -605,8 +604,7 @@ void netfs_write_collection_worker(struct work_struct *work)
 
 	_debug("finished");
 	trace_netfs_rreq(wreq, netfs_rreq_trace_wake_ip);
-	clear_bit_unlock(NETFS_RREQ_IN_PROGRESS, &wreq->flags);
-	wake_up_bit(&wreq->flags, NETFS_RREQ_IN_PROGRESS);
+	clear_and_wake_up_bit(NETFS_RREQ_IN_PROGRESS, &wreq->flags);
 
 	if (wreq->iocb) {
 		size_t written = min(wreq->transferred, wreq->len);
@@ -714,8 +712,7 @@ void netfs_write_subrequest_terminated(void *_op, ssize_t transferred_or_error,
 
 	trace_netfs_sreq(subreq, netfs_sreq_trace_terminated);
 
-	clear_bit_unlock(NETFS_SREQ_IN_PROGRESS, &subreq->flags);
-	wake_up_bit(&subreq->flags, NETFS_SREQ_IN_PROGRESS);
+	clear_and_wake_up_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags);
 
 	/* If we are at the head of the queue, wake up the collector,
 	 * transferring a ref to it if we were the ones to do so.
-- 
2.39.5

[PATCH 6.12 012/189] netfs: Fix ceph copy to cache on write-begin

[Greg Kroah-Hartman]

6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Howells <dhowells@redhat.com>

[ Upstream commit 38cf8e945721ffe708fa675507465da7f4f2a9f7 ]

At the end of netfs_unlock_read_folio() in which folios are marked
appropriately for copying to the cache (either with by being marked dirty
and having their private data set or by having PG_private_2 set) and then
unlocked, the folio_queue struct has the entry pointing to the folio
cleared.  This presents a problem for netfs_pgpriv2_write_to_the_cache(),
which is used to write folios marked with PG_private_2 to the cache as it
expects to be able to trawl the folio_queue list thereafter to find the
relevant folios, leading to a hang.

Fix this by not clearing the folio_queue entry if we're going to do the
deprecated copy-to-cache.  The clearance will be done instead as the folios
are written to the cache.

This can be reproduced by starting cachefiles, mounting a ceph filesystem
with "-o fsc" and writing to it.

Fixes: 796a4049640b ("netfs: In readahead, put the folio refs as soon extracted")
Reported-by: Max Kellermann <max.kellermann@ionos.com>
Closes: https://lore.kernel.org/r/CAKPOu+_4m80thNy5_fvROoxBm689YtA0dZ-=gcmkzwYSY4syqw@mail.gmail.com/
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20241213135013.2964079-10-dhowells@redhat.com
Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading")
cc: Jeff Layton <jlayton@kernel.org>
cc: Ilya Dryomov <idryomov@gmail.com>
cc: Xiubo Li <xiubli@redhat.com>
cc: netfs@lists.linux.dev
cc: ceph-devel@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/netfs/read_collect.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/netfs/read_collect.c b/fs/netfs/read_collect.c
index d86fa02f68fb..e70eb4ea21c0 100644
--- a/fs/netfs/read_collect.c
+++ b/fs/netfs/read_collect.c
@@ -62,10 +62,14 @@ static void netfs_unlock_read_folio(struct netfs_io_subrequest *subreq,
 		} else {
 			trace_netfs_folio(folio, netfs_folio_trace_read_done);
 		}
+
+		folioq_clear(folioq, slot);
 	} else {
 		// TODO: Use of PG_private_2 is deprecated.
 		if (test_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags))
 			netfs_pgpriv2_mark_copy_to_cache(subreq, rreq, folioq, slot);
+		else
+			folioq_clear(folioq, slot);
 	}
 
 	if (!test_bit(NETFS_RREQ_DONT_UNLOCK_FOLIOS, &rreq->flags)) {
@@ -77,8 +81,6 @@ static void netfs_unlock_read_folio(struct netfs_io_subrequest *subreq,
 			folio_unlock(folio);
 		}
 	}
-
-	folioq_clear(folioq, slot);
 }
 
 /*
-- 
2.39.5

[PATCH 6.12 013/189] netfs: Fix the (non-)cancellation of copy when cache is temporarily disabled

[Greg Kroah-Hartman]

6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Howells <dhowells@redhat.com>

[ Upstream commit d0327c824338cdccad058723a31d038ecd553409 ]

When the caching for a cookie is temporarily disabled (e.g. due to a DIO
write on that file), future copying to the cache for that file is disabled
until all fds open on that file are closed.  However, if netfslib is using
the deprecated PG_private_2 method (such as is currently used by ceph), and
decides it wants to copy to the cache, netfs_advance_write() will just bail
at the first check seeing that the cache stream is unavailable, and
indicate that it dealt with all the content.

This means that we have no subrequests to provide notifications to drive
the state machine or even to pin the request and the request just gets
discarded, leaving the folios with PG_private_2 set.

Fix this by jumping directly to cancel the request if the cache is not
available.  That way, we don't remove mark3 from the folio_queue list and
netfs_pgpriv2_cancel() will clean up the folios.

This was found by running the generic/013 xfstest against ceph with an
active cache and the "-o fsc" option passed to ceph.  That would usually
hang

Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading")
Reported-by: Max Kellermann <max.kellermann@ionos.com>
Closes: https://lore.kernel.org/r/CAKPOu+_4m80thNy5_fvROoxBm689YtA0dZ-=gcmkzwYSY4syqw@mail.gmail.com/
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20241213135013.2964079-11-dhowells@redhat.com
cc: Jeff Layton <jlayton@kernel.org>
cc: Ilya Dryomov <idryomov@gmail.com>
cc: Xiubo Li <xiubli@redhat.com>
cc: netfs@lists.linux.dev
cc: ceph-devel@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/netfs/read_pgpriv2.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/netfs/read_pgpriv2.c b/fs/netfs/read_pgpriv2.c
index ba5af89d37fa..54d5004fec18 100644
--- a/fs/netfs/read_pgpriv2.c
+++ b/fs/netfs/read_pgpriv2.c
@@ -170,6 +170,10 @@ void netfs_pgpriv2_write_to_the_cache(struct netfs_io_request *rreq)
 
 	trace_netfs_write(wreq, netfs_write_trace_copy_to_cache);
 	netfs_stat(&netfs_n_wh_copy_to_cache);
+	if (!wreq->io_streams[1].avail) {
+		netfs_put_request(wreq, false, netfs_rreq_trace_put_return);
+		goto couldnt_start;
+	}
 
 	for (;;) {
 		error = netfs_pgpriv2_copy_folio(wreq, folio);
-- 
2.39.5

[PATCH 6.12 014/189] netfs: Fix is-caching check in read-retry

[Greg Kroah-Hartman]

6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Howells <dhowells@redhat.com>

[ Upstream commit d4e338de17cb6532bf805fae00db8b41e914009b ]

netfs: Fix is-caching check in read-retry

The read-retry code checks the NETFS_RREQ_COPY_TO_CACHE flag to determine
if there might be failed reads from the cache that need turning into reads
from the server, with the intention of skipping the complicated part if it
can.  The code that set the flag, however, got lost during the read-side
rewrite.

Fix the check to see if the cache_resources are valid instead.  The flag
can then be removed.

Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading")
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/3752048.1734381285@warthog.procyon.org.uk
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/netfs/read_retry.c | 2 +-
 include/linux/netfs.h | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/netfs/read_retry.c b/fs/netfs/read_retry.c
index 0350592ea804..2701f7d45999 100644
--- a/fs/netfs/read_retry.c
+++ b/fs/netfs/read_retry.c
@@ -49,7 +49,7 @@ static void netfs_retry_read_subrequests(struct netfs_io_request *rreq)
 	 * up to the first permanently failed one.
 	 */
 	if (!rreq->netfs_ops->prepare_read &&
-	    !test_bit(NETFS_RREQ_COPY_TO_CACHE, &rreq->flags)) {
+	    !rreq->cache_resources.ops) {
 		struct netfs_io_subrequest *subreq;
 
 		list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index 5eaceef41e6c..474481ee8b7c 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -269,7 +269,6 @@ struct netfs_io_request {
 	size_t			prev_donated;	/* Fallback for subreq->prev_donated */
 	refcount_t		ref;
 	unsigned long		flags;
-#define NETFS_RREQ_COPY_TO_CACHE	1	/* Need to write to the cache */
 #define NETFS_RREQ_NO_UNLOCK_FOLIO	2	/* Don't unlock no_unlock_folio on completion */
 #define NETFS_RREQ_DONT_UNLOCK_FOLIOS	3	/* Don't unlock the folios on completion */
 #define NETFS_RREQ_FAILED		4	/* The request failed */
-- 
2.39.5

[PATCH 6.12 081/189] netfs: Fix kernel async DIO

[Greg Kroah-Hartman]

6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Howells <dhowells@redhat.com>

[ Upstream commit 3f6bc9e3ab9b127171d39f9ac6eca1abb693b731 ]

Netfslib needs to be able to handle kernel-initiated asynchronous DIO that
is supplied with a bio_vec[] array.  Currently, because of the async flag,
this gets passed to netfs_extract_user_iter() which throws a warning and
fails because it only handles IOVEC and UBUF iterators.  This can be
triggered through a combination of cifs and a loopback blockdev with
something like:

        mount //my/cifs/share /foo
        dd if=/dev/zero of=/foo/m0 bs=4K count=1K
        losetup --sector-size 4096 --direct-io=on /dev/loop2046 /foo/m0
        echo hello >/dev/loop2046

This causes the following to appear in syslog:

        WARNING: CPU: 2 PID: 109 at fs/netfs/iterator.c:50 netfs_extract_user_iter+0x170/0x250 [netfs]

and the write to fail.

Fix this by removing the check in netfs_unbuffered_write_iter_locked() that
causes async kernel DIO writes to be handled as userspace writes.  Note
that this change relies on the kernel caller maintaining the existence of
the bio_vec array (or kvec[] or folio_queue) until the op is complete.

Fixes: 153a9961b551 ("netfs: Implement unbuffered/DIO write support")
Reported-by: Nicolas Baranger <nicolas.baranger@3xo.fr>
Closes: https://lore.kernel.org/r/fedd8a40d54b2969097ffa4507979858@3xo.fr/
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/608725.1736275167@warthog.procyon.org.uk
Tested-by: Nicolas Baranger <nicolas.baranger@3xo.fr>
Acked-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
cc: Steve French <smfrench@gmail.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/netfs/direct_write.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/netfs/direct_write.c b/fs/netfs/direct_write.c
index 88f2adfab75e..26cf9c94deeb 100644
--- a/fs/netfs/direct_write.c
+++ b/fs/netfs/direct_write.c
@@ -67,7 +67,7 @@ ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *
 		 * allocate a sufficiently large bvec array and may shorten the
 		 * request.
 		 */
-		if (async || user_backed_iter(iter)) {
+		if (user_backed_iter(iter)) {
 			n = netfs_extract_user_iter(iter, len, &wreq->iter, 0);
 			if (n < 0) {
 				ret = n;
@@ -77,6 +77,11 @@ ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *
 			wreq->direct_bv_count = n;
 			wreq->direct_bv_unpin = iov_iter_extract_will_pin(iter);
 		} else {
+			/* If this is a kernel-generated async DIO request,
+			 * assume that any resources the iterator points to
+			 * (eg. a bio_vec array) will persist till the end of
+			 * the op.
+			 */
 			wreq->iter = *iter;
 		}
 
-- 
2.39.5

[PATCH 6.12 082/189] netfs: Fix read-retry for fs with no ->prepare_read()

[Greg Kroah-Hartman]

6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Howells <dhowells@redhat.com>

[ Upstream commit 904abff4b1b94184aaa0e9f5fce7821f7b5b81a3 ]

Fix netfslib's read-retry to only call ->prepare_read() in the backing
filesystem such a function is provided.  We can get to this point if a
there's an active cache as failed reads from the cache need negotiating
with the server instead.

Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading")
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/529329.1736261010@warthog.procyon.org.uk
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/netfs/read_retry.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/netfs/read_retry.c b/fs/netfs/read_retry.c
index 2701f7d45999..48fb0303f7ee 100644
--- a/fs/netfs/read_retry.c
+++ b/fs/netfs/read_retry.c
@@ -149,7 +149,8 @@ static void netfs_retry_read_subrequests(struct netfs_io_request *rreq)
 			BUG_ON(!len);
 
 			/* Renegotiate max_len (rsize) */
-			if (rreq->netfs_ops->prepare_read(subreq) < 0) {
+			if (rreq->netfs_ops->prepare_read &&
+			    rreq->netfs_ops->prepare_read(subreq) < 0) {
 				trace_netfs_sreq(subreq, netfs_sreq_trace_reprep_failed);
 				__set_bit(NETFS_SREQ_FAILED, &subreq->flags);
 			}
-- 
2.39.5