Merge tag 'vfs-6.10-rc8.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs fixes from Christian Brauner:
 "cachefiles:

   - Export an existing and add a new cachefile helper to be used in
     filesystems to fix reference count bugs

   - Use the newly added fscache_ty_get_volume() helper to get a
     reference count on an fscache_volume to handle volumes that are
     about to be removed cleanly

   - After withdrawing a fscache_cache via FSCACHE_CACHE_IS_WITHDRAWN
     wait for all ongoing cookie lookups to complete and for the object
     count to reach zero

   - Propagate errors from vfs_getxattr() to avoid an infinite loop in
     cachefiles_check_volume_xattr() because it keeps seeing ESTALE

   - Don't send new requests when an object is dropped by raising
     CACHEFILES_ONDEMAND_OJBSTATE_DROPPING

   - Cancel all requests for an object that is about to be dropped

   - Wait for the ondemand_boject_worker to finish before dropping a
     cachefiles object to prevent use-after-free

   - Use cyclic allocation for message ids to better handle id recycling

   - Add missing lock protection when iterating through the xarray when
     polling

  netfs:

   - Use standard logging helpers for debug logging

  VFS:

   - Fix potential use-after-free in file locks during
     trace_posix_lock_inode(). The tracepoint could fire while another
     task raced it and freed the lock that was requested to be traced

   - Only increment the nr_dentry_negative counter for dentries that are
     present on the superblock LRU. Currently, DCACHE_LRU_LIST list is
     used to detect this case. However, the flag is also raised in
     combination with DCACHE_SHRINK_LIST to indicate that dentry->d_lru
     is used. So checking only DCACHE_LRU_LIST will lead to wrong
     nr_dentry_negative count. Fix the check to not count dentries that
     are on a shrink related list

  Misc:

   - hfsplus: fix an uninitialized value issue in copy_name

   - minix: fix minixfs_rename with HIGHMEM. It still uses kunmap() even
     though we switched it to kmap_local_page() a while ago"

* tag 'vfs-6.10-rc8.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  minixfs: Fix minixfs_rename with HIGHMEM
  hfsplus: fix uninit-value in copy_name
  vfs: don't mod negative dentry count when on shrinker list
  filelock: fix potential use-after-free in posix_lock_inode
  cachefiles: add missing lock protection when polling
  cachefiles: cyclic allocation of msg_id to avoid reuse
  cachefiles: wait for ondemand_object_worker to finish when dropping object
  cachefiles: cancel all requests for the object that is being dropped
  cachefiles: stop sending new request when dropping object
  cachefiles: propagate errors from vfs_getxattr() to avoid infinite loop
  cachefiles: fix slab-use-after-free in cachefiles_withdraw_cookie()
  cachefiles: fix slab-use-after-free in fscache_withdraw_volume()
  netfs, fscache: export fscache_put_volume() and add fscache_try_get_volume()
  netfs: Switch debug logging to pr_debug()

27 files changed, 213 insertions, 133 deletions

diff --git a/fs/cachefiles/cache.c b/fs/cachefiles/cache.c
index f449f7340aad..9fb06dc16520 100644
--- a/fs/cachefiles/cache.c
+++ b/fs/cachefiles/cache.c
@@ -8,6 +8,7 @@
 #include <linux/slab.h>
 #include <linux/statfs.h>
 #include <linux/namei.h>
+#include <trace/events/fscache.h>
 #include "internal.h"
 
 /*
@@ -312,19 +313,59 @@ static void cachefiles_withdraw_objects(struct cachefiles_cache *cache)
 }
 
 /*
- * Withdraw volumes.
+ * Withdraw fscache volumes.
+ */
+static void cachefiles_withdraw_fscache_volumes(struct cachefiles_cache *cache)
+{
+	struct list_head *cur;
+	struct cachefiles_volume *volume;
+	struct fscache_volume *vcookie;
+
+	_enter("");
+retry:
+	spin_lock(&cache->object_list_lock);
+	list_for_each(cur, &cache->volumes) {
+		volume = list_entry(cur, struct cachefiles_volume, cache_link);
+
+		if (atomic_read(&volume->vcookie->n_accesses) == 0)
+			continue;
+
+		vcookie = fscache_try_get_volume(volume->vcookie,
+						 fscache_volume_get_withdraw);
+		if (vcookie) {
+			spin_unlock(&cache->object_list_lock);
+			fscache_withdraw_volume(vcookie);
+			fscache_put_volume(vcookie, fscache_volume_put_withdraw);
+			goto retry;
+		}
+	}
+	spin_unlock(&cache->object_list_lock);
+
+	_leave("");
+}
+
+/*
+ * Withdraw cachefiles volumes.
  */
 static void cachefiles_withdraw_volumes(struct cachefiles_cache *cache)
 {
 	_enter("");
 
 	for (;;) {
+		struct fscache_volume *vcookie = NULL;
 		struct cachefiles_volume *volume = NULL;
 
 		spin_lock(&cache->object_list_lock);
 		if (!list_empty(&cache->volumes)) {
 			volume = list_first_entry(&cache->volumes,
 						  struct cachefiles_volume, cache_link);
+			vcookie = fscache_try_get_volume(volume->vcookie,
+							 fscache_volume_get_withdraw);
+			if (!vcookie) {
+				spin_unlock(&cache->object_list_lock);
+				cpu_relax();
+				continue;
+			}
 			list_del_init(&volume->cache_link);
 		}
 		spin_unlock(&cache->object_list_lock);
@@ -332,6 +373,7 @@ static void cachefiles_withdraw_volumes(struct cachefiles_cache *cache)
 			break;
 
 		cachefiles_withdraw_volume(volume);
+		fscache_put_volume(vcookie, fscache_volume_put_withdraw);
 	}
 
 	_leave("");
@@ -371,6 +413,7 @@ void cachefiles_withdraw_cache(struct cachefiles_cache *cache)
 	pr_info("File cache on %s unregistering\n", fscache->name);
 
 	fscache_withdraw_cache(fscache);
+	cachefiles_withdraw_fscache_volumes(cache);
 
 	/* we now have to destroy all the active objects pertaining to this
 	 * cache - which we do by passing them off to thread pool to be
diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c
index 06cdf1a8a16f..89b11336a836 100644
--- a/fs/cachefiles/daemon.c
+++ b/fs/cachefiles/daemon.c
@@ -366,14 +366,14 @@ static __poll_t cachefiles_daemon_poll(struct file *file,
 
 	if (cachefiles_in_ondemand_mode(cache)) {
 		if (!xa_empty(&cache->reqs)) {
-			rcu_read_lock();
+			xas_lock(&xas);
 			xas_for_each_marked(&xas, req, ULONG_MAX, CACHEFILES_REQ_NEW) {
 				if (!cachefiles_ondemand_is_reopening_read(req)) {
 					mask |= EPOLLIN;
 					break;
 				}
 			}
-			rcu_read_unlock();
+			xas_unlock(&xas);
 		}
 	} else {
 		if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h
index 6845a90cdfcc..7b99bd98de75 100644
--- a/fs/cachefiles/internal.h
+++ b/fs/cachefiles/internal.h
@@ -48,6 +48,7 @@ enum cachefiles_object_state {
 	CACHEFILES_ONDEMAND_OBJSTATE_CLOSE, /* Anonymous fd closed by daemon or initial state */
 	CACHEFILES_ONDEMAND_OBJSTATE_OPEN, /* Anonymous fd associated with object is available */
 	CACHEFILES_ONDEMAND_OBJSTATE_REOPENING, /* Object that was closed and is being reopened. */
+	CACHEFILES_ONDEMAND_OBJSTATE_DROPPING, /* Object is being dropped. */
 };
 
 struct cachefiles_ondemand_info {
@@ -128,6 +129,7 @@ struct cachefiles_cache {
 	unsigned long			req_id_next;
 	struct xarray			ondemand_ids;	/* xarray for ondemand_id allocation */
 	u32				ondemand_id_next;
+	u32				msg_id_next;
 };
 
 static inline bool cachefiles_in_ondemand_mode(struct cachefiles_cache *cache)
@@ -335,6 +337,7 @@ cachefiles_ondemand_set_object_##_state(struct cachefiles_object *object) \
 CACHEFILES_OBJECT_STATE_FUNCS(open, OPEN);
 CACHEFILES_OBJECT_STATE_FUNCS(close, CLOSE);
 CACHEFILES_OBJECT_STATE_FUNCS(reopening, REOPENING);
+CACHEFILES_OBJECT_STATE_FUNCS(dropping, DROPPING);
 
 static inline bool cachefiles_ondemand_is_reopening_read(struct cachefiles_req *req)
 {
diff --git a/fs/cachefiles/ondemand.c b/fs/cachefiles/ondemand.c
index bce005f2b456..470c96658385 100644
--- a/fs/cachefiles/ondemand.c
+++ b/fs/cachefiles/ondemand.c
@@ -517,7 +517,8 @@ static int cachefiles_ondemand_send_req(struct cachefiles_object *object,
 		 */
 		xas_lock(&xas);
 
-		if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
+		if (test_bit(CACHEFILES_DEAD, &cache->flags) ||
+		    cachefiles_ondemand_object_is_dropping(object)) {
 			xas_unlock(&xas);
 			ret = -EIO;
 			goto out;
@@ -527,20 +528,32 @@ static int cachefiles_ondemand_send_req(struct cachefiles_object *object,
 		smp_mb();
 
 		if (opcode == CACHEFILES_OP_CLOSE &&
-			!cachefiles_ondemand_object_is_open(object)) {
+		    !cachefiles_ondemand_object_is_open(object)) {
 			WARN_ON_ONCE(object->ondemand->ondemand_id == 0);
 			xas_unlock(&xas);
 			ret = -EIO;
 			goto out;
 		}
 
-		xas.xa_index = 0;
+		/*
+		 * Cyclically find a free xas to avoid msg_id reuse that would
+		 * cause the daemon to successfully copen a stale msg_id.
+		 */
+		xas.xa_index = cache->msg_id_next;
 		xas_find_marked(&xas, UINT_MAX, XA_FREE_MARK);
+		if (xas.xa_node == XAS_RESTART) {
+			xas.xa_index = 0;
+			xas_find_marked(&xas, cache->msg_id_next - 1, XA_FREE_MARK);
+		}
 		if (xas.xa_node == XAS_RESTART)
 			xas_set_err(&xas, -EBUSY);
+
 		xas_store(&xas, req);
-		xas_clear_mark(&xas, XA_FREE_MARK);
-		xas_set_mark(&xas, CACHEFILES_REQ_NEW);
+		if (xas_valid(&xas)) {
+			cache->msg_id_next = xas.xa_index + 1;
+			xas_clear_mark(&xas, XA_FREE_MARK);
+			xas_set_mark(&xas, CACHEFILES_REQ_NEW);
+		}
 		xas_unlock(&xas);
 	} while (xas_nomem(&xas, GFP_KERNEL));
 
@@ -568,7 +581,8 @@ out:
 	 * If error occurs after creating the anonymous fd,
 	 * cachefiles_ondemand_fd_release() will set object to close.
 	 */
-	if (opcode == CACHEFILES_OP_OPEN)
+	if (opcode == CACHEFILES_OP_OPEN &&
+	    !cachefiles_ondemand_object_is_dropping(object))
 		cachefiles_ondemand_set_object_close(object);
 	kfree(req);
 	return ret;
@@ -667,8 +681,34 @@ int cachefiles_ondemand_init_object(struct cachefiles_object *object)
 
 void cachefiles_ondemand_clean_object(struct cachefiles_object *object)
 {
+	unsigned long index;
+	struct cachefiles_req *req;
+	struct cachefiles_cache *cache;
+
+	if (!object->ondemand)
+		return;
+
 	cachefiles_ondemand_send_req(object, CACHEFILES_OP_CLOSE, 0,
 			cachefiles_ondemand_init_close_req, NULL);
+
+	if (!object->ondemand->ondemand_id)
+		return;
+
+	/* Cancel all requests for the object that is being dropped. */
+	cache = object->volume->cache;
+	xa_lock(&cache->reqs);
+	cachefiles_ondemand_set_object_dropping(object);
+	xa_for_each(&cache->reqs, index, req) {
+		if (req->object == object) {
+			req->error = -EIO;
+			complete(&req->done);
+			__xa_erase(&cache->reqs, index);
+		}
+	}
+	xa_unlock(&cache->reqs);
+
+	/* Wait for ondemand_object_worker() to finish to avoid UAF. */
+	cancel_work_sync(&object->ondemand->ondemand_work);
 }
 
 int cachefiles_ondemand_init_obj_info(struct cachefiles_object *object,
diff --git a/fs/cachefiles/volume.c b/fs/cachefiles/volume.c
index 89df0ba8ba5e..781aac4ef274 100644
--- a/fs/cachefiles/volume.c
+++ b/fs/cachefiles/volume.c
@@ -133,7 +133,6 @@ void cachefiles_free_volume(struct fscache_volume *vcookie)
 
 void cachefiles_withdraw_volume(struct cachefiles_volume *volume)
 {
-	fscache_withdraw_volume(volume->vcookie);
 	cachefiles_set_volume_xattr(volume);
 	__cachefiles_free_volume(volume);
 }
diff --git a/fs/cachefiles/xattr.c b/fs/cachefiles/xattr.c
index bcb6173943ee..4dd8a993c60a 100644
--- a/fs/cachefiles/xattr.c
+++ b/fs/cachefiles/xattr.c
@@ -110,9 +110,11 @@ int cachefiles_check_auxdata(struct cachefiles_object *object, struct file *file
 	if (xlen == 0)
 		xlen = vfs_getxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache, buf, tlen);
 	if (xlen != tlen) {
-		if (xlen < 0)
+		if (xlen < 0) {
+			ret = xlen;
 			trace_cachefiles_vfs_error(object, file_inode(file), xlen,
 						   cachefiles_trace_getxattr_error);
+		}
 		if (xlen == -EIO)
 			cachefiles_io_error_obj(
 				object,
@@ -252,6 +254,7 @@ int cachefiles_check_volume_xattr(struct cachefiles_volume *volume)
 		xlen = vfs_getxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache, buf, len);
 	if (xlen != len) {
 		if (xlen < 0) {
+			ret = xlen;
 			trace_cachefiles_vfs_error(NULL, d_inode(dentry), xlen,
 						   cachefiles_trace_getxattr_error);
 			if (xlen == -EIO)
diff --git a/fs/dcache.c b/fs/dcache.c
index d58dc9e58f3b..4c144519aa70 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -355,7 +355,11 @@ static inline void __d_clear_type_and_inode(struct dentry *dentry)
 	flags &= ~DCACHE_ENTRY_TYPE;
 	WRITE_ONCE(dentry->d_flags, flags);
 	dentry->d_inode = NULL;
-	if (flags & DCACHE_LRU_LIST)
+	/*
+	 * The negative counter only tracks dentries on the LRU. Don't inc if
+	 * d_lru is on another list.
+	 */
+	if ((flags & (DCACHE_LRU_LIST|DCACHE_SHRINK_LIST)) == DCACHE_LRU_LIST)
 		this_cpu_inc(nr_dentry_negative);
 }
 
@@ -1844,9 +1848,11 @@ static void __d_instantiate(struct dentry *dentry, struct inode *inode)
 
 	spin_lock(&dentry->d_lock);
 	/*
-	 * Decrement negative dentry count if it was in the LRU list.
+	 * The negative counter only tracks dentries on the LRU. Don't dec if
+	 * d_lru is on another list.
 	 */
-	if (dentry->d_flags & DCACHE_LRU_LIST)
+	if ((dentry->d_flags &
+	     (DCACHE_LRU_LIST|DCACHE_SHRINK_LIST)) == DCACHE_LRU_LIST)
 		this_cpu_dec(nr_dentry_negative);
 	hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry);
 	raw_write_seqcount_begin(&dentry->d_seq);
diff --git a/fs/hfsplus/xattr.c b/fs/hfsplus/xattr.c
index 5a400259ae74..9a1a93e3888b 100644
--- a/fs/hfsplus/xattr.c
+++ b/fs/hfsplus/xattr.c
@@ -696,7 +696,7 @@ ssize_t hfsplus_listxattr(struct dentry *dentry, char *buffer, size_t size)
 		return err;
 	}
 
-	strbuf = kmalloc(NLS_MAX_CHARSET_SIZE * HFSPLUS_ATTR_MAX_STRLEN +
+	strbuf = kzalloc(NLS_MAX_CHARSET_SIZE * HFSPLUS_ATTR_MAX_STRLEN +
 			XATTR_MAC_OSX_PREFIX_LEN + 1, GFP_KERNEL);
 	if (!strbuf) {
 		res = -ENOMEM;
diff --git a/fs/locks.c b/fs/locks.c
index c360d1992d21..bdd94c32256f 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1367,9 +1367,9 @@ retry:
 		locks_wake_up_blocks(&left->c);
 	}
  out:
+	trace_posix_lock_inode(inode, request, error);
 	spin_unlock(&ctx->flc_lock);
 	percpu_up_read(&file_rwsem);
-	trace_posix_lock_inode(inode, request, error);
 	/*
 	 * Free any unused locks.
 	 */
diff --git a/fs/minix/namei.c b/fs/minix/namei.c
index d6031acc34f0..a944a0f17b53 100644
--- a/fs/minix/namei.c
+++ b/fs/minix/namei.c
@@ -213,8 +213,7 @@ static int minix_rename(struct mnt_idmap *idmap,
 		if (!new_de)
 			goto out_dir;
 		err = minix_set_link(new_de, new_page, old_inode);
-		kunmap(new_page);
-		put_page(new_page);
+		unmap_and_put_page(new_page, new_de);
 		if (err)
 			goto out_dir;
 		inode_set_ctime_current(new_inode);
diff --git a/fs/netfs/buffered_read.c b/fs/netfs/buffered_read.c
index a6bb03bea920..4c0401dbbfcf 100644
--- a/fs/netfs/buffered_read.c
+++ b/fs/netfs/buffered_read.c
@@ -117,7 +117,7 @@ void netfs_rreq_unlock_folios(struct netfs_io_request *rreq)
 		if (!test_bit(NETFS_RREQ_DONT_UNLOCK_FOLIOS, &rreq->flags)) {
 			if (folio->index == rreq->no_unlock_folio &&
 			    test_bit(NETFS_RREQ_NO_UNLOCK_FOLIO, &rreq->flags))
-				_debug("no unlock");
+				kdebug("no unlock");
 			else
 				folio_unlock(folio);
 		}
@@ -204,7 +204,7 @@ void netfs_readahead(struct readahead_control *ractl)
 	struct netfs_inode *ctx = netfs_inode(ractl->mapping->host);
 	int ret;
 
-	_enter("%lx,%x", readahead_index(ractl), readahead_count(ractl));
+	kenter("%lx,%x", readahead_index(ractl), readahead_count(ractl));
 
 	if (readahead_count(ractl) == 0)
 		return;
@@ -268,7 +268,7 @@ int netfs_read_folio(struct file *file, struct folio *folio)
 	struct folio *sink = NULL;
 	int ret;
 
-	_enter("%lx", folio->index);
+	kenter("%lx", folio->index);
 
 	rreq = netfs_alloc_request(mapping, file,
 				   folio_file_pos(folio), folio_size(folio),
@@ -508,7 +508,7 @@ retry:
 
 have_folio:
 	*_folio = folio;
-	_leave(" = 0");
+	kleave(" = 0");
 	return 0;
 
 error_put:
@@ -518,7 +518,7 @@ error:
 		folio_unlock(folio);
 		folio_put(folio);
 	}
-	_leave(" = %d", ret);
+	kleave(" = %d", ret);
 	return ret;
 }
 EXPORT_SYMBOL(netfs_write_begin);
@@ -536,7 +536,7 @@ int netfs_prefetch_for_write(struct file *file, struct folio *folio,
 	size_t flen = folio_size(folio);
 	int ret;
 
-	_enter("%zx @%llx", flen, start);
+	kenter("%zx @%llx", flen, start);
 
 	ret = -ENOMEM;
 
@@ -567,7 +567,7 @@ int netfs_prefetch_for_write(struct file *file, struct folio *folio,
 error_put:
 	netfs_put_request(rreq, false, netfs_rreq_trace_put_discard);
 error:
-	_leave(" = %d", ret);
+	kleave(" = %d", ret);
 	return ret;
 }
 
diff --git a/fs/netfs/buffered_write.c b/fs/netfs/buffered_write.c
index d583af7a2209..ecbc99ec7d36 100644
--- a/fs/netfs/buffered_write.c
+++ b/fs/netfs/buffered_write.c
@@ -56,7 +56,7 @@ static enum netfs_how_to_modify netfs_how_to_modify(struct netfs_inode *ctx,
 	struct netfs_group *group = netfs_folio_group(folio);
 	loff_t pos = folio_file_pos(folio);
 
-	_enter("");
+	kenter("");
 
 	if (group != netfs_group && group != NETFS_FOLIO_COPY_TO_CACHE)
 		return NETFS_FLUSH_CONTENT;
@@ -272,12 +272,12 @@ ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
 		 */
 		howto = netfs_how_to_modify(ctx, file, folio, netfs_group,
 					    flen, offset, part, maybe_trouble);
-		_debug("howto %u", howto);
+		kdebug("howto %u", howto);
 		switch (howto) {
 		case NETFS_JUST_PREFETCH:
 			ret = netfs_prefetch_for_write(file, folio, offset, part);
 			if (ret < 0) {
-				_debug("prefetch = %zd", ret);
+				kdebug("prefetch = %zd", ret);
 				goto error_folio_unlock;
 			}
 			break;
@@ -418,7 +418,7 @@ out:
 	}
 
 	iocb->ki_pos += written;
-	_leave(" = %zd [%zd]", written, ret);
+	kleave(" = %zd [%zd]", written, ret);
 	return written ? written : ret;
 
 error_folio_unlock:
@@ -491,7 +491,7 @@ ssize_t netfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	struct netfs_inode *ictx = netfs_inode(inode);
 	ssize_t ret;
 
-	_enter("%llx,%zx,%llx", iocb->ki_pos, iov_iter_count(from), i_size_read(inode));
+	kenter("%llx,%zx,%llx", iocb->ki_pos, iov_iter_count(from), i_size_read(inode));
 
 	if (!iov_iter_count(from))
 		return 0;
@@ -529,7 +529,7 @@ vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_gr
 	vm_fault_t ret = VM_FAULT_RETRY;
 	int err;
 
-	_enter("%lx", folio->index);
+	kenter("%lx", folio->index);
 
 	sb_start_pagefault(inode->i_sb);
 
diff --git a/fs/netfs/direct_read.c b/fs/netfs/direct_read.c
index 10a1e4da6bda..b6debac6205f 100644
--- a/fs/netfs/direct_read.c
+++ b/fs/netfs/direct_read.c
@@ -33,7 +33,7 @@ ssize_t netfs_unbuffered_read_iter_locked(struct kiocb *iocb, struct iov_iter *i
 	size_t orig_count = iov_iter_count(iter);
 	bool async = !is_sync_kiocb(iocb);
 
-	_enter("");
+	kenter("");
 
 	if (!orig_count)
 		return 0; /* Don't update atime */
diff --git a/fs/netfs/direct_write.c b/fs/netfs/direct_write.c
index 88f2adfab75e..792ef17bae21 100644
--- a/fs/netfs/direct_write.c
+++ b/fs/netfs/direct_write.c
@@ -37,7 +37,7 @@ ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *
 	size_t len = iov_iter_count(iter);
 	bool async = !is_sync_kiocb(iocb);
 
-	_enter("");
+	kenter("");
 
 	/* We're going to need a bounce buffer if what we transmit is going to
 	 * be different in some way to the source buffer, e.g. because it gets
@@ -45,7 +45,7 @@ ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *
 	 */
 	// TODO
 
-	_debug("uw %llx-%llx", start, end);
+	kdebug("uw %llx-%llx", start, end);
 
 	wreq = netfs_create_write_req(iocb->ki_filp->f_mapping, iocb->ki_filp, start,
 				      iocb->ki_flags & IOCB_DIRECT ?
@@ -96,7 +96,7 @@ ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *
 	wreq->cleanup = netfs_cleanup_dio_write;
 	ret = netfs_unbuffered_write(wreq, is_sync_kiocb(iocb), wreq->len);
 	if (ret < 0) {
-		_debug("begin = %zd", ret);
+		kdebug("begin = %zd", ret);
 		goto out;
 	}
 
@@ -143,7 +143,7 @@ ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	loff_t pos = iocb->ki_pos;
 	unsigned long long end = pos + iov_iter_count(from) - 1;
 
-	_enter("%llx,%zx,%llx", pos, iov_iter_count(from), i_size_read(inode));
+	kenter("%llx,%zx,%llx", pos, iov_iter_count(from), i_size_read(inode));
 
 	if (!iov_iter_count(from))
 		return 0;
diff --git a/fs/netfs/fscache_cache.c b/fs/netfs/fscache_cache.c
index 9397ed39b0b4..288a73c3072d 100644
--- a/fs/netfs/fscache_cache.c
+++ b/fs/netfs/fscache_cache.c
@@ -237,7 +237,7 @@ int fscache_add_cache(struct fscache_cache *cache,
 {
 	int n_accesses;
 
-	_enter("{%s,%s}", ops->name, cache->name);
+	kenter("{%s,%s}", ops->name, cache->name);
 
 	BUG_ON(fscache_cache_state(cache) != FSCACHE_CACHE_IS_PREPARING);
 
@@ -257,7 +257,7 @@ int fscache_add_cache(struct fscache_cache *cache,
 
 	up_write(&fscache_addremove_sem);
 	pr_notice("Cache \"%s\" added (type %s)\n", cache->name, ops->name);
-	_leave(" = 0 [%s]", cache->name);
+	kleave(" = 0 [%s]", cache->name);
 	return 0;
 }
 EXPORT_SYMBOL(fscache_add_cache);
diff --git a/fs/netfs/fscache_cookie.c b/fs/netfs/fscache_cookie.c
index bce2492186d0..4d1e8bf4c615 100644
--- a/fs/netfs/fscache_cookie.c
+++ b/fs/netfs/fscache_cookie.c
@@ -456,7 +456,7 @@ struct fscache_cookie *__fscache_acquire_cookie(
 {
 	struct fscache_cookie *cookie;
 
-	_enter("V=%x", volume->debug_id);
+	kenter("V=%x", volume->debug_id);
 
 	if (!index_key || !index_key_len || index_key_len > 255 || aux_data_len > 255)
 		return NULL;
@@ -484,7 +484,7 @@ struct fscache_cookie *__fscache_acquire_cookie(
 
 	trace_fscache_acquire(cookie);
 	fscache_stat(&fscache_n_acquires_ok);
-	_leave(" = c=%08x", cookie->debug_id);
+	kleave(" = c=%08x", cookie->debug_id);
 	return cookie;
 }
 EXPORT_SYMBOL(__fscache_acquire_cookie);
@@ -505,7 +505,7 @@ static void fscache_perform_lookup(struct fscache_cookie *cookie)
 	enum fscache_access_trace trace = fscache_access_lookup_cookie_end_failed;
 	bool need_withdraw = false;
 
-	_enter("");
+	kenter("");
 
 	if (!cookie->volume->cache_priv) {
 		fscache_create_volume(cookie->volume, true);
@@ -519,7 +519,7 @@ static void fscache_perform_lookup(struct fscache_cookie *cookie)
 		if (cookie->state != FSCACHE_COOKIE_STATE_FAILED)
 			fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_QUIESCENT);
 		need_withdraw = true;
-		_leave(" [fail]");
+		kleave(" [fail]");
 		goto out;
 	}
 
@@ -572,7 +572,7 @@ void __fscache_use_cookie(struct fscache_cookie *cookie, bool will_modify)
 	bool queue = false;
 	int n_active;
 
-	_enter("c=%08x", cookie->debug_id);
+	kenter("c=%08x", cookie->debug_id);
 
 	if (WARN(test_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags),
 		 "Trying to use relinquished cookie\n"))
@@ -636,7 +636,7 @@ again:
 	spin_unlock(&cookie->lock);
 	if (queue)
 		fscache_queue_cookie(cookie, fscache_cookie_get_use_work);
-	_leave("");
+	kleave("");
 }
 EXPORT_SYMBOL(__fscache_use_cookie);
 
@@ -702,7 +702,7 @@ static void fscache_cookie_state_machine(struct fscache_cookie *cookie)
 	enum fscache_cookie_state state;
 	bool wake = false;
 
-	_enter("c=%x", cookie->debug_id);
+	kenter("c=%x", cookie->debug_id);
 
 again:
 	spin_lock(&cookie->lock);
@@ -820,7 +820,7 @@ out:
 	spin_unlock(&cookie->lock);
 	if (wake)
 		wake_up_cookie_state(cookie);
-	_leave("");
+	kleave("");
 }
 
 static void fscache_cookie_worker(struct work_struct *work)
@@ -867,7 +867,7 @@ static void fscache_cookie_lru_do_one(struct fscache_cookie *cookie)
 		set_bit(FSCACHE_COOKIE_DO_LRU_DISCARD, &cookie->flags);
 		spin_unlock(&cookie->lock);
 		fscache_stat(&fscache_n_cookies_lru_expired);
-		_debug("lru c=%x", cookie->debug_id);
+		kdebug("lru c=%x", cookie->debug_id);
 		__fscache_withdraw_cookie(cookie);
 	}
 
@@ -971,7 +971,7 @@ void __fscache_relinquish_cookie(struct fscache_cookie *cookie, bool retire)
 	if (retire)
 		fscache_stat(&fscache_n_relinquishes_retire);
 
-	_enter("c=%08x{%d},%d",
+	kenter("c=%08x{%d},%d",
 	       cookie->debug_id, atomic_read(&cookie->n_active), retire);
 
 	if (WARN(test_and_set_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags),
@@ -1050,7 +1050,7 @@ void __fscache_invalidate(struct fscache_cookie *cookie,
 {
 	bool is_caching;
 
-	_enter("c=%x", cookie->debug_id);
+	kenter("c=%x", cookie->debug_id);
 
 	fscache_stat(&fscache_n_invalidates);
 
@@ -1072,7 +1072,7 @@ void __fscache_invalidate(struct fscache_cookie *cookie,
 	case FSCACHE_COOKIE_STATE_INVALIDATING: /* is_still_valid will catch it */
 	default:
 		spin_unlock(&cookie->lock);
-		_leave(" [no %u]", cookie->state);
+		kleave(" [no %u]", cookie->state);
 		return;
 
 	case FSCACHE_COOKIE_STATE_LOOKING_UP:
@@ -1081,7 +1081,7 @@ void __fscache_invalidate(struct fscache_cookie *cookie,
 		fallthrough;
 	case FSCACHE_COOKIE_STATE_CREATING:
 		spin_unlock(&cookie->lock);
-		_leave(" [look %x]", cookie->inval_counter);
+		kleave(" [look %x]", cookie->inval_counter);
 		return;
 
 	case FSCACHE_COOKIE_STATE_ACTIVE:
@@ -1094,7 +1094,7 @@ void __fscache_invalidate(struct fscache_cookie *cookie,
 
 		if (is_caching)
 			fscache_queue_cookie(cookie, fscache_cookie_get_inval_work);
-		_leave(" [inv]");
+		kleave(" [inv]");
 		return;
 	}
 }
diff --git a/fs/netfs/fscache_io.c b/fs/netfs/fscache_io.c
index 38637e5c9b57..bf4eaeec44fb 100644
--- a/fs/netfs/fscache_io.c
+++ b/fs/netfs/fscache_io.c
@@ -28,12 +28,12 @@ bool fscache_wait_for_operation(struct netfs_cache_resources *cres,
 
 again:
 	if (!fscache_cache_is_live(cookie->volume->cache)) {
-		_leave(" [broken]");
+		kleave(" [broken]");
 		return false;
 	}
 
 	state = fscache_cookie_state(cookie);
-	_enter("c=%08x{%u},%x", cookie->debug_id, state, want_state);
+	kenter("c=%08x{%u},%x", cookie->debug_id, state, want_state);
 
 	switch (state) {
 	case FSCACHE_COOKIE_STATE_CREATING:
@@ -52,7 +52,7 @@ again:
 	case FSCACHE_COOKIE_STATE_DROPPED:
 	case FSCACHE_COOKIE_STATE_RELINQUISHING:
 	default:
-		_leave(" [not live]");
+		kleave(" [not live]");
 		return false;
 	}
 
@@ -92,7 +92,7 @@ again:
 	spin_lock(&cookie->lock);
 
 	state = fscache_cookie_state(cookie);
-	_enter("c=%08x{%u},%x", cookie->debug_id, state, want_state);
+	kenter("c=%08x{%u},%x", cookie->debug_id, state, want_state);
 
 	switch (state) {
 	case FSCACHE_COOKIE_STATE_LOOKING_UP:
@@ -140,7 +140,7 @@ failed:
 	cres->cache_priv = NULL;
 	cres->ops = NULL;
 	fscache_end_cookie_access(cookie, fscache_access_io_not_live);
-	_leave(" = -ENOBUFS");
+	kleave(" = -ENOBUFS");
 	return -ENOBUFS;
 }
 
@@ -224,7 +224,7 @@ void __fscache_write_to_cache(struct fscache_cookie *cookie,
 	if (len == 0)
 		goto abandon;
 
-	_enter("%llx,%zx", start, len);
+	kenter("%llx,%zx", start, len);
 
 	wreq = kzalloc(sizeof(struct fscache_write_request), GFP_NOFS);
 	if (!wreq)
diff --git a/fs/netfs/fscache_main.c b/fs/netfs/fscache_main.c
index 42e98bb523e3..bf9b33d26e31 100644
--- a/fs/netfs/fscache_main.c
+++ b/fs/netfs/fscache_main.c
@@ -99,7 +99,7 @@ error_wq:
  */
 void __exit fscache_exit(void)
 {
-	_enter("");
+	kenter("");
 
 	kmem_cache_destroy(fscache_cookie_jar);
 	fscache_proc_cleanup();
diff --git a/fs/netfs/fscache_volume.c b/fs/netfs/fscache_volume.c
index cdf991bdd9de..2e2a405ca9b0 100644
--- a/fs/netfs/fscache_volume.c
+++ b/fs/netfs/fscache_volume.c
@@ -27,6 +27,19 @@ struct fscache_volume *fscache_get_volume(struct fscache_volume *volume,
 	return volume;
 }
 
+struct fscache_volume *fscache_try_get_volume(struct fscache_volume *volume,
+					      enum fscache_volume_trace where)
+{
+	int ref;
+
+	if (!__refcount_inc_not_zero(&volume->ref, &ref))
+		return NULL;
+
+	trace_fscache_volume(volume->debug_id, ref + 1, where);
+	return volume;
+}
+EXPORT_SYMBOL(fscache_try_get_volume);
+
 static void fscache_see_volume(struct fscache_volume *volume,
 			       enum fscache_volume_trace where)
 {
@@ -251,7 +264,7 @@ static struct fscache_volume *fscache_alloc_volume(const char *volume_key,
 	fscache_see_volume(volume, fscache_volume_new_acquire);
 	fscache_stat(&fscache_n_volumes);
 	up_write(&fscache_addremove_sem);
-	_leave(" = v=%x", volume->debug_id);
+	kleave(" = v=%x", volume->debug_id);
 	return volume;
 
 err_vol:
@@ -420,6 +433,7 @@ void fscache_put_volume(struct fscache_volume *volume,
 			fscache_free_volume(volume);
 	}
 }
+EXPORT_SYMBOL(fscache_put_volume);
 
 /*
  * Relinquish a volume representation cookie.
@@ -452,7 +466,7 @@ void fscache_withdraw_volume(struct fscache_volume *volume)
 {
 	int n_accesses;
 
-	_debug("withdraw V=%x", volume->debug_id);
+	kdebug("withdraw V=%x", volume->debug_id);
 
 	/* Allow wakeups on dec-to-0 */
 	n_accesses = atomic_dec_return(&volume->n_accesses);
diff --git a/fs/netfs/internal.h b/fs/netfs/internal.h
index acd9ca14e264..21e46bc9aa49 100644
--- a/fs/netfs/internal.h
+++ b/fs/netfs/internal.h
@@ -34,7 +34,6 @@ int netfs_begin_read(struct netfs_io_request *rreq, bool sync);
 /*
  * main.c
  */
-extern unsigned int netfs_debug;
 extern struct list_head netfs_io_requests;
 extern spinlock_t netfs_proc_lock;
 extern mempool_t netfs_request_pool;
@@ -344,8 +343,6 @@ extern const struct seq_operations fscache_volumes_seq_ops;
 
 struct fscache_volume *fscache_get_volume(struct fscache_volume *volume,
 					  enum fscache_volume_trace where);
-void fscache_put_volume(struct fscache_volume *volume,
-			enum fscache_volume_trace where);
 bool fscache_begin_volume_access(struct fscache_volume *volume,
 				 struct fscache_cookie *cookie,
 				 enum fscache_access_trace why);
@@ -356,42 +353,12 @@ void fscache_create_volume(struct fscache_volume *volume, bool wait);
  * debug tracing
  */
 #define dbgprintk(FMT, ...) \
-	printk("[%-6.6s] "FMT"\n", current->comm, ##__VA_ARGS__)
+	pr_debug("[%-6.6s] "FMT"\n", current->comm, ##__VA_ARGS__)
 
 #define kenter(FMT, ...) dbgprintk("==> %s("FMT")", __func__, ##__VA_ARGS__)
 #define kleave(FMT, ...) dbgprintk("<== %s()"FMT"", __func__, ##__VA_ARGS__)
 #define kdebug(FMT, ...) dbgprintk(FMT, ##__VA_ARGS__)
 
-#ifdef __KDEBUG
-#define _enter(FMT, ...) kenter(FMT, ##__VA_ARGS__)
-#define _leave(FMT, ...) kleave(FMT, ##__VA_ARGS__)
-#define _debug(FMT, ...) kdebug(FMT, ##__VA_ARGS__)
-
-#elif defined(CONFIG_NETFS_DEBUG)
-#define _enter(FMT, ...)			\
-do {						\
-	if (netfs_debug)			\
-		kenter(FMT, ##__VA_ARGS__);	\
-} while (0)
-
-#define _leave(FMT, ...)			\
-do {						\
-	if (netfs_debug)			\
-		kleave(FMT, ##__VA_ARGS__);	\
-} while (0)
-
-#define _debug(FMT, ...)			\
-do {						\
-	if (netfs_debug)			\
-		kdebug(FMT, ##__VA_ARGS__);	\
-} while (0)
-
-#else
-#define _enter(FMT, ...) no_printk("==> %s("FMT")", __func__, ##__VA_ARGS__)
-#define _leave(FMT, ...) no_printk("<== %s()"FMT"", __func__, ##__VA_ARGS__)
-#define _debug(FMT, ...) no_printk(FMT, ##__VA_ARGS__)
-#endif
-
 /*
  * assertions
  */
diff --git a/fs/netfs/io.c b/fs/netfs/io.c
index c93851b98368..c7576481c321 100644
--- a/fs/netfs/io.c
+++ b/fs/netfs/io.c
@@ -130,7 +130,7 @@ static void netfs_reset_subreq_iter(struct netfs_io_request *rreq,
 	if (count == remaining)
 		return;
 
-	_debug("R=%08x[%u] ITER RESUB-MISMATCH %zx != %zx-%zx-%llx %x\n",
+	kdebug("R=%08x[%u] ITER RESUB-MISMATCH %zx != %zx-%zx-%llx %x\n",
 	       rreq->debug_id, subreq->debug_index,
 	       iov_iter_count(&subreq->io_iter), subreq->transferred,
 	       subreq->len, rreq->i_size,
@@ -326,7 +326,7 @@ void netfs_subreq_terminated(struct netfs_io_subrequest *subreq,
 	struct netfs_io_request *rreq = subreq->rreq;
 	int u;
 
-	_enter("R=%x[%x]{%llx,%lx},%zd",
+	kenter("R=%x[%x]{%llx,%lx},%zd",
 	       rreq->debug_id, subreq->debug_index,
 	       subreq->start, subreq->flags, transferred_or_error);
 
@@ -435,7 +435,7 @@ netfs_rreq_prepare_read(struct netfs_io_request *rreq,
 	struct netfs_inode *ictx = netfs_inode(rreq->inode);
 	size_t lsize;
 
-	_enter("%llx-%llx,%llx", subreq->start, subreq->start + subreq->len, rreq->i_size);
+	kenter("%llx-%llx,%llx", subreq->start, subreq->start + subreq->len, rreq->i_size);
 
 	if (rreq->origin != NETFS_DIO_READ) {
 		source = netfs_cache_prepare_read(subreq, rreq->i_size);
@@ -518,7 +518,7 @@ static bool netfs_rreq_submit_slice(struct netfs_io_request *rreq,
 	subreq->start		= rreq->start + rreq->submitted;
 	subreq->len		= io_iter->count;
 
-	_debug("slice %llx,%zx,%llx", subreq->start, subreq->len, rreq->submitted);
+	kdebug("slice %llx,%zx,%llx", subreq->start, subreq->len, rreq->submitted);
 	list_add_tail(&subreq->rreq_link, &rreq->subrequests);
 
 	/* Call out to the cache to find out what it can do with the remaining
@@ -570,7 +570,7 @@ int netfs_begin_read(struct netfs_io_request *rreq, bool sync)
 	struct iov_iter io_iter;
 	int ret;
 
-	_enter("R=%x %llx-%llx",
+	kenter("R=%x %llx-%llx",
 	       rreq->debug_id, rreq->start, rreq->start + rreq->len - 1);
 
 	if (rreq->len == 0) {
@@ -593,7 +593,7 @@ int netfs_begin_read(struct netfs_io_request *rreq, bool sync)
 	atomic_set(&rreq->nr_outstanding, 1);
 	io_iter = rreq->io_iter;
 	do {
-		_debug("submit %llx + %llx >= %llx",
+		kdebug("submit %llx + %llx >= %llx",
 		       rreq->start, rreq->submitted, rreq->i_size);
 		if (rreq->origin == NETFS_DIO_READ &&
 		    rreq->start + rreq->submitted >= rreq->i_size)
diff --git a/fs/netfs/main.c b/fs/netfs/main.c
index 5f0f438e5d21..db824c372842 100644
--- a/fs/netfs/main.c
+++ b/fs/netfs/main.c
@@ -20,10 +20,6 @@ MODULE_LICENSE("GPL");
 
 EXPORT_TRACEPOINT_SYMBOL(netfs_sreq);
 
-unsigned netfs_debug;
-module_param_named(debug, netfs_debug, uint, S_IWUSR | S_IRUGO);
-MODULE_PARM_DESC(netfs_debug, "Netfs support debugging mask");
-
 static struct kmem_cache *netfs_request_slab;
 static struct kmem_cache *netfs_subrequest_slab;
 mempool_t netfs_request_pool;
diff --git a/fs/netfs/misc.c b/fs/netfs/misc.c
index 83e644bd518f..172808e83ca8 100644
--- a/fs/netfs/misc.c
+++ b/fs/netfs/misc.c
@@ -26,7 +26,7 @@ bool netfs_dirty_folio(struct address_space *mapping, struct folio *folio)
 	struct fscache_cookie *cookie = netfs_i_cookie(ictx);
 	bool need_use = false;
 
-	_enter("");
+	kenter("");
 
 	if (!filemap_dirty_folio(mapping, folio))
 		return false;
@@ -99,7 +99,7 @@ void netfs_invalidate_folio(struct folio *folio, size_t offset, size_t length)
 	struct netfs_folio *finfo;
 	size_t flen = folio_size(folio);
 
-	_enter("{%lx},%zx,%zx", folio->index, offset, length);
+	kenter("{%lx},%zx,%zx", folio->index, offset, length);
 
 	if (!folio_test_private(folio))
 		return;
diff --git a/fs/netfs/write_collect.c b/fs/netfs/write_collect.c
index 426cf87aaf2e..488147439fe0 100644
--- a/fs/netfs/write_collect.c
+++ b/fs/netfs/write_collect.c
@@ -161,7 +161,7 @@ static void netfs_retry_write_stream(struct netfs_io_request *wreq,
 {
 	struct list_head *next;
 
-	_enter("R=%x[%x:]", wreq->debug_id, stream->stream_nr);
+	kenter("R=%x[%x:]", wreq->debug_id, stream->stream_nr);
 
 	if (list_empty(&stream->subrequests))
 		return;
@@ -374,7 +374,7 @@ static void netfs_collect_write_results(struct netfs_io_request *wreq)
 	unsigned int notes;
 	int s;
 
-	_enter("%llx-%llx", wreq->start, wreq->start + wreq->len);
+	kenter("%llx-%llx", wreq->start, wreq->start + wreq->len);
 	trace_netfs_collect(wreq);
 	trace_netfs_rreq(wreq, netfs_rreq_trace_collect);
 
@@ -409,7 +409,7 @@ reassess_streams:
 		front = stream->front;
 		while (front) {
 			trace_netfs_collect_sreq(wreq, front);
-			//_debug("sreq [%x] %llx %zx/%zx",
+			//kdebug("sreq [%x] %llx %zx/%zx",
 			//       front->debug_index, front->start, front->transferred, front->len);
 
 			/* Stall if there may be a discontinuity. */
@@ -598,7 +598,7 @@ reassess_streams:
 out:
 	netfs_put_group_many(wreq->group, wreq->nr_group_rel);
 	wreq->nr_group_rel = 0;
-	_leave(" = %x", notes);
+	kleave(" = %x", notes);
 	return;
 
 need_retry:
@@ -606,7 +606,7 @@ need_retry:
 	 * that any partially completed op will have had any wholly transferred
 	 * folios removed from it.
 	 */
-	_debug("retry");
+	kdebug("retry");
 	netfs_retry_writes(wreq);
 	goto out;
 }
@@ -621,7 +621,7 @@ void netfs_write_collection_worker(struct work_struct *work)
 	size_t transferred;
 	int s;
 
-	_enter("R=%x", wreq->debug_id);
+	kenter("R=%x", wreq->debug_id);
 
 	netfs_see_request(wreq, netfs_rreq_trace_see_work);
 	if (!test_bit(NETFS_RREQ_IN_PROGRESS, &wreq->flags)) {
@@ -684,7 +684,7 @@ void netfs_write_collection_worker(struct work_struct *work)
 	if (wreq->origin == NETFS_DIO_WRITE)
 		inode_dio_end(wreq->inode);
 
-	_debug("finished");
+	kdebug("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);
@@ -744,7 +744,7 @@ void netfs_write_subrequest_terminated(void *_op, ssize_t transferred_or_error,
 	struct netfs_io_request *wreq = subreq->rreq;
 	struct netfs_io_stream *stream = &wreq->io_streams[subreq->stream_nr];
 
-	_enter("%x[%x] %zd", wreq->debug_id, subreq->debug_index, transferred_or_error);
+	kenter("%x[%x] %zd", wreq->debug_id, subreq->debug_index, transferred_or_error);
 
 	switch (subreq->source) {
 	case NETFS_UPLOAD_TO_SERVER:
diff --git a/fs/netfs/write_issue.c b/fs/netfs/write_issue.c
index ec6cf8707fb0..d7c971df8866 100644
--- a/fs/netfs/write_issue.c
+++ b/fs/netfs/write_issue.c
@@ -99,7 +99,7 @@ struct netfs_io_request *netfs_create_write_req(struct address_space *mapping,
 	if (IS_ERR(wreq))
 		return wreq;
 
-	_enter("R=%x", wreq->debug_id);
+	kenter("R=%x", wreq->debug_id);
 
 	ictx = netfs_inode(wreq->inode);
 	if (test_bit(NETFS_RREQ_WRITE_TO_CACHE, &wreq->flags))
@@ -159,7 +159,7 @@ static void netfs_prepare_write(struct netfs_io_request *wreq,
 	subreq->max_nr_segs	= INT_MAX;
 	subreq->stream_nr	= stream->stream_nr;
 
-	_enter("R=%x[%x]", wreq->debug_id, subreq->debug_index);
+	kenter("R=%x[%x]", wreq->debug_id, subreq->debug_index);
 
 	trace_netfs_sreq_ref(wreq->debug_id, subreq->debug_index,
 			     refcount_read(&subreq->ref),
@@ -215,7 +215,7 @@ static void netfs_do_issue_write(struct netfs_io_stream *stream,
 {
 	struct netfs_io_request *wreq = subreq->rreq;
 
-	_enter("R=%x[%x],%zx", wreq->debug_id, subreq->debug_index, subreq->len);
+	kenter("R=%x[%x],%zx", wreq->debug_id, subreq->debug_index, subreq->len);
 
 	if (test_bit(NETFS_SREQ_FAILED, &subreq->flags))
 		return netfs_write_subrequest_terminated(subreq, subreq->error, false);
@@ -272,11 +272,11 @@ int netfs_advance_write(struct netfs_io_request *wreq,
 	size_t part;
 
 	if (!stream->avail) {
-		_leave("no write");
+		kleave("no write");
 		return len;
 	}
 
-	_enter("R=%x[%x]", wreq->debug_id, subreq ? subreq->debug_index : 0);
+	kenter("R=%x[%x]", wreq->debug_id, subreq ? subreq->debug_index : 0);
 
 	if (subreq && start != subreq->start + subreq->len) {
 		netfs_issue_write(wreq, stream);
@@ -288,7 +288,7 @@ int netfs_advance_write(struct netfs_io_request *wreq,
 	subreq = stream->construct;
 
 	part = min(subreq->max_len - subreq->len, len);
-	_debug("part %zx/%zx %zx/%zx", subreq->len, subreq->max_len, part, len);
+	kdebug("part %zx/%zx %zx/%zx", subreq->len, subreq->max_len, part, len);
 	subreq->len += part;
 	subreq->nr_segs++;
 
@@ -319,7 +319,7 @@ static int netfs_write_folio(struct netfs_io_request *wreq,
 	bool to_eof = false, streamw = false;
 	bool debug = false;
 
-	_enter("");
+	kenter("");
 
 	/* netfs_perform_write() may shift i_size around the page or from out
 	 * of the page to beyond it, but cannot move i_size into or through the
@@ -329,7 +329,7 @@ static int netfs_write_folio(struct netfs_io_request *wreq,
 
 	if (fpos >= i_size) {
 		/* mmap beyond eof. */
-		_debug("beyond eof");
+		kdebug("beyond eof");
 		folio_start_writeback(folio);
 		folio_unlock(folio);
 		wreq->nr_group_rel += netfs_folio_written_back(folio);
@@ -363,7 +363,7 @@ static int netfs_write_folio(struct netfs_io_request *wreq,
 	}
 	flen -= foff;
 
-	_debug("folio %zx %zx %zx", foff, flen, fsize);
+	kdebug("folio %zx %zx %zx", foff, flen, fsize);
 
 	/* Deal with discontinuities in the stream of dirty pages.  These can
 	 * arise from a number of sources:
@@ -487,7 +487,7 @@ static int netfs_write_folio(struct netfs_io_request *wreq,
 		for (int s = 0; s < NR_IO_STREAMS; s++)
 			netfs_issue_write(wreq, &wreq->io_streams[s]);
 
-	_leave(" = 0");
+	kleave(" = 0");
 	return 0;
 }
 
@@ -522,7 +522,7 @@ int netfs_writepages(struct address_space *mapping,
 	netfs_stat(&netfs_n_wh_writepages);
 
 	do {
-		_debug("wbiter %lx %llx", folio->index, wreq->start + wreq->submitted);
+		kdebug("wbiter %lx %llx", folio->index, wreq->start + wreq->submitted);
 
 		/* It appears we don't have to handle cyclic writeback wrapping. */
 		WARN_ON_ONCE(wreq && folio_pos(folio) < wreq->start + wreq->submitted);
@@ -546,14 +546,14 @@ int netfs_writepages(struct address_space *mapping,
 	mutex_unlock(&ictx->wb_lock);
 
 	netfs_put_request(wreq, false, netfs_rreq_trace_put_return);
-	_leave(" = %d", error);
+	kleave(" = %d", error);
 	return error;
 
 couldnt_start:
 	netfs_kill_dirty_pages(mapping, wbc, folio);
 out:
 	mutex_unlock(&ictx->wb_lock);
-	_leave(" = %d", error);
+	kleave(" = %d", error);
 	return error;
 }
 EXPORT_SYMBOL(netfs_writepages);
@@ -590,7 +590,7 @@ int netfs_advance_writethrough(struct netfs_io_request *wreq, struct writeback_c
 			       struct folio *folio, size_t copied, bool to_page_end,
 			       struct folio **writethrough_cache)
 {
-	_enter("R=%x ic=%zu ws=%u cp=%zu tp=%u",
+	kenter("R=%x ic=%zu ws=%u cp=%zu tp=%u",
 	       wreq->debug_id, wreq->iter.count, wreq->wsize, copied, to_page_end);
 
 	if (!*writethrough_cache) {
@@ -624,7 +624,7 @@ int netfs_end_writethrough(struct netfs_io_request *wreq, struct writeback_contr
 	struct netfs_inode *ictx = netfs_inode(wreq->inode);
 	int ret;
 
-	_enter("R=%x", wreq->debug_id);
+	kenter("R=%x", wreq->debug_id);
 
 	if (writethrough_cache)
 		netfs_write_folio(wreq, wbc, writethrough_cache);
@@ -657,7 +657,7 @@ int netfs_unbuffered_write(struct netfs_io_request *wreq, bool may_wait, size_t
 	loff_t start = wreq->start;
 	int error = 0;
 
-	_enter("%zx", len);
+	kenter("%zx", len);
 
 	if (wreq->origin == NETFS_DIO_WRITE)
 		inode_dio_begin(wreq->inode);
@@ -665,7 +665,7 @@ int netfs_unbuffered_write(struct netfs_io_request *wreq, bool may_wait, size_t
 	while (len) {
 		// TODO: Prepare content encryption
 
-		_debug("unbuffered %zx", len);
+		kdebug("unbuffered %zx", len);
 		part = netfs_advance_write(wreq, upload, start, len, false);
 		start += part;
 		len -= part;
@@ -684,6 +684,6 @@ int netfs_unbuffered_write(struct netfs_io_request *wreq, bool may_wait, size_t
 	if (list_empty(&upload->subrequests))
 		netfs_wake_write_collector(wreq, false);
 
-	_leave(" = %d", error);
+	kleave(" = %d", error);
 	return error;
 }
diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h
index bdf7f3eddf0a..4c91a019972b 100644
--- a/include/linux/fscache-cache.h
+++ b/include/linux/fscache-cache.h
@@ -19,6 +19,7 @@
 enum fscache_cache_trace;
 enum fscache_cookie_trace;
 enum fscache_access_trace;
+enum fscache_volume_trace;
 
 enum fscache_cache_state {
 	FSCACHE_CACHE_IS_NOT_PRESENT,	/* No cache is present for this name */
@@ -97,6 +98,11 @@ extern void fscache_withdraw_cookie(struct fscache_cookie *cookie);
 
 extern void fscache_io_error(struct fscache_cache *cache);
 
+extern struct fscache_volume *
+fscache_try_get_volume(struct fscache_volume *volume,
+		       enum fscache_volume_trace where);
+extern void fscache_put_volume(struct fscache_volume *volume,
+			       enum fscache_volume_trace where);
 extern void fscache_end_volume_access(struct fscache_volume *volume,
 				      struct fscache_cookie *cookie,
 				      enum fscache_access_trace why);
diff --git a/include/trace/events/fscache.h b/include/trace/events/fscache.h
index a6190aa1b406..f1a73aa83fbb 100644
--- a/include/trace/events/fscache.h
+++ b/include/trace/events/fscache.h
@@ -35,12 +35,14 @@ enum fscache_volume_trace {
 	fscache_volume_get_cookie,
 	fscache_volume_get_create_work,
 	fscache_volume_get_hash_collision,
+	fscache_volume_get_withdraw,
 	fscache_volume_free,
 	fscache_volume_new_acquire,
 	fscache_volume_put_cookie,
 	fscache_volume_put_create_work,
 	fscache_volume_put_hash_collision,
 	fscache_volume_put_relinquish,
+	fscache_volume_put_withdraw,
 	fscache_volume_see_create_work,
 	fscache_volume_see_hash_wake,
 	fscache_volume_wait_create_work,
@@ -120,12 +122,14 @@ enum fscache_access_trace {
 	EM(fscache_volume_get_cookie,		"GET cook ")		\
 	EM(fscache_volume_get_create_work,	"GET creat")		\
 	EM(fscache_volume_get_hash_collision,	"GET hcoll")		\
+	EM(fscache_volume_get_withdraw,		"GET withd")            \
 	EM(fscache_volume_free,			"FREE     ")		\
 	EM(fscache_volume_new_acquire,		"NEW acq  ")		\
 	EM(fscache_volume_put_cookie,		"PUT cook ")		\
 	EM(fscache_volume_put_create_work,	"PUT creat")		\
 	EM(fscache_volume_put_hash_collision,	"PUT hcoll")		\
 	EM(fscache_volume_put_relinquish,	"PUT relnq")		\
+	EM(fscache_volume_put_withdraw,		"PUT withd")            \
 	EM(fscache_volume_see_create_work,	"SEE creat")		\
 	EM(fscache_volume_see_hash_wake,	"SEE hwake")		\
 	E_(fscache_volume_wait_create_work,	"WAIT crea")