[RFC PATCH v6 0/4] fuse: work queues to invalided dentries

[RFC PATCH v6 0/4] fuse: work queues to invalided dentries

[Luis Henriques]

Hi Miklos,

Here's a new version of the patchset to invalidate expired dentries.  Most
of the changes (and there are a lot of them!) result from the v5 review.
See below for details.

Changes since v5:

- Changes to dcache: export shrink_dentry_list() and add new helper
  d_dispose_if_unused()
- Reduced hash lock array size
- Set 'inval_wq' max value to USHRT_MAX to prevent a potential overflow in
  secs_to_jiffies()
- Updated 'inval_wq' parameter description and comment
- Removed useless check in fuse_dentry_tree_del_node()
- Make fuse_dentry_tree_work() use dcache helpers d_dispose_if_unused() and
  shrink_dentry_list()
- Fix usage of need_resched() (replaced with cond_resched())
- fuse_dentry_tree_cleanup() now simply does a WARN_ON() if there are
  non-empty trees
- Removed TODO comment in fuse_conn_destroy() -- no need to prune trees
- Have fuse_epoch_work() use of shrink_dcache_sb() instead of going through
  all the trees
- Refactor fuse_conn_put() in a separate patch
- Fix bug in fuse_dentry_tree_add_node() for cases where dentries have the
  same timeout
- Reword some of the commits text

Changes since v4:
 
- Dropped extra check in fuse_dentry_tree_add_node() (Chunsheng)
- Make the dentries trees global instead of per fuse_conn (Miklos)
- Protect trees with hashed locking instead of a single lock (Miklos)
- Added new work queue (2nd patch) specifically to handle epoch (Miklos)
 
Changes since v3:
 
- Use of need_resched() instead of limiting the work queue to run for 5
  seconds
- Restore usage of union with rcu_head, in struct fuse_dentry
- Minor changes in comments (e.g. s/workqueue/work queue/)
 
Changes since v2:
 
- Major rework, the dentries tree nodes are now in fuse_dentry and they are
  tied to the actual dentry lifetime
- Mount option is now a module parameter
- workqueue now runs for at most 5 seconds before rescheduling

Luis Henriques (4):
  dcache: export shrink_dentry_list() and new helper
    d_dispose_if_unused()
  fuse: new work queue to periodically invalidate expired dentries
  fuse: new work queue to invalidate dentries from old epochs
  fuse: refactor fuse_conn_put() to remove negative logic.

 fs/dcache.c            |  18 ++--
 fs/fuse/dev.c          |   7 +-
 fs/fuse/dir.c          | 237 +++++++++++++++++++++++++++++++++++++----
 fs/fuse/fuse_i.h       |  14 +++
 fs/fuse/inode.c        |  44 ++++----
 include/linux/dcache.h |   2 +
 6 files changed, 273 insertions(+), 49 deletions(-)

[RFC PATCH v6 1/4] dcache: export shrink_dentry_list() and add new helper d_dispose_if_unused()

[Luis Henriques]

Add and export a new helper d_dispose_if_unused() which is simply a wrapper
around to_shrink_list(), to add an entry to a dispose list if it's not used
anymore.

Also export shrink_dentry_list() to kill all dentries in a dispose list.

Suggested-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Luis Henriques <luis@igalia.com>
---
 fs/dcache.c            | 18 ++++++++++++------
 include/linux/dcache.h |  2 ++
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index 60046ae23d51..3adefe05583c 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1086,6 +1086,15 @@ struct dentry *d_find_alias_rcu(struct inode *inode)
 	return de;
 }
 
+void d_dispose_if_unused(struct dentry *dentry, struct list_head *dispose)
+{
+	spin_lock(&dentry->d_lock);
+	if (!dentry->d_lockref.count)
+		to_shrink_list(dentry, dispose);
+	spin_unlock(&dentry->d_lock);
+}
+EXPORT_SYMBOL(d_dispose_if_unused);
+
 /*
  *	Try to kill dentries associated with this inode.
  * WARNING: you must own a reference to inode.
@@ -1096,12 +1105,8 @@ void d_prune_aliases(struct inode *inode)
 	struct dentry *dentry;
 
 	spin_lock(&inode->i_lock);
-	hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) {
-		spin_lock(&dentry->d_lock);
-		if (!dentry->d_lockref.count)
-			to_shrink_list(dentry, &dispose);
-		spin_unlock(&dentry->d_lock);
-	}
+	hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias)
+		d_dispose_if_unused(dentry, &dispose);
 	spin_unlock(&inode->i_lock);
 	shrink_dentry_list(&dispose);
 }
@@ -1141,6 +1146,7 @@ void shrink_dentry_list(struct list_head *list)
 		shrink_kill(dentry);
 	}
 }
+EXPORT_SYMBOL(shrink_dentry_list);
 
 static enum lru_status dentry_lru_isolate(struct list_head *item,
 		struct list_lru_one *lru, void *arg)
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index cc3e1c1a3454..4ef41a5debdc 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -265,6 +265,8 @@ extern void d_tmpfile(struct file *, struct inode *);
 
 extern struct dentry *d_find_alias(struct inode *);
 extern void d_prune_aliases(struct inode *);
+extern void d_dispose_if_unused(struct dentry *, struct list_head *);
+extern void shrink_dentry_list(struct list_head *);
 
 extern struct dentry *d_find_alias_rcu(struct inode *);
 

[RFC PATCH v6 2/4] fuse: new work queue to periodically invalidate expired dentries

[Luis Henriques]

This patch adds the necessary infrastructure to keep track of all dentries
created for FUSE file systems.  A set of rbtrees, protected by hashed
locks, will be used to keep all these dentries sorted by expiry time.

A new module parameter 'inval_wq' is also added.  When set, it will start
a work queue which will periodically invalidate expired dentries.  The
value of this new parameter is the period, in seconds, for this work
queue.  Once this parameter is set, every new dentry will be added to one
of the rbtrees.

When the work queue is executed, it will check all the rbtrees and will
invalidate those dentries that have timed-out.

The work queue period can not be smaller than 5 seconds, but can be
disabled by setting 'inval_wq' to zero (which is the default).

Signed-off-by: Luis Henriques <luis@igalia.com>
---
 fs/fuse/dir.c    | 216 ++++++++++++++++++++++++++++++++++++++++++-----
 fs/fuse/fuse_i.h |  10 +++
 fs/fuse/inode.c  |   3 +
 3 files changed, 208 insertions(+), 21 deletions(-)

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 5c569c3cb53f..3e88da803ba6 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -27,6 +27,67 @@ module_param(allow_sys_admin_access, bool, 0644);
 MODULE_PARM_DESC(allow_sys_admin_access,
 		 "Allow users with CAP_SYS_ADMIN in initial userns to bypass allow_other access check");
 
+struct dentry_bucket {
+	struct rb_root tree;
+	spinlock_t lock;
+};
+
+#define HASH_BITS	5
+#define HASH_SIZE	(1 << HASH_BITS)
+static struct dentry_bucket dentry_hash[HASH_SIZE];
+struct delayed_work dentry_tree_work;
+
+/* Minimum invalidation work queue frequency */
+#define FUSE_DENTRY_INVAL_FREQ_MIN 5
+
+unsigned __read_mostly inval_wq;
+static int inval_wq_set(const char *val, const struct kernel_param *kp)
+{
+	unsigned int num;
+	unsigned int old = inval_wq;
+	int ret;
+
+	if (!val)
+		return -EINVAL;
+
+	ret = kstrtouint(val, 0, &num);
+	if (ret)
+		return ret;
+
+	if ((num < FUSE_DENTRY_INVAL_FREQ_MIN) && (num != 0))
+		return -EINVAL;
+
+	/* This should prevent overflow in secs_to_jiffies() */
+	if (num > USHRT_MAX)
+		return -EINVAL;
+
+	*((unsigned int *)kp->arg) = num;
+
+	if (num && !old)
+		schedule_delayed_work(&dentry_tree_work,
+				      secs_to_jiffies(num));
+	else if (!num && old)
+		cancel_delayed_work_sync(&dentry_tree_work);
+
+	return 0;
+}
+static const struct kernel_param_ops inval_wq_ops = {
+	.set = inval_wq_set,
+	.get = param_get_uint,
+};
+module_param_cb(inval_wq, &inval_wq_ops, &inval_wq, 0644);
+__MODULE_PARM_TYPE(inval_wq, "uint");
+MODULE_PARM_DESC(inval_wq,
+		 "Dentries invalidation work queue period in secs (>= "
+		 __stringify(FUSE_DENTRY_INVAL_FREQ_MIN) ").");
+
+static inline struct dentry_bucket *get_dentry_bucket(struct dentry *dentry)
+{
+	int i = hash_ptr(dentry, HASH_BITS);
+
+	return &dentry_hash[i];
+}
+
 static void fuse_advise_use_readdirplus(struct inode *dir)
 {
 	struct fuse_inode *fi = get_fuse_inode(dir);
@@ -34,33 +95,131 @@ static void fuse_advise_use_readdirplus(struct inode *dir)
 	set_bit(FUSE_I_ADVISE_RDPLUS, &fi->state);
 }
 
-#if BITS_PER_LONG >= 64
-static inline void __fuse_dentry_settime(struct dentry *entry, u64 time)
+struct fuse_dentry {
+	u64 time;
+	union {
+		struct rcu_head rcu;
+		struct rb_node node;
+	};
+	struct dentry *dentry;
+};
+
+static void __fuse_dentry_tree_del_node(struct fuse_dentry *fd,
+					struct dentry_bucket *bucket)
 {
-	entry->d_fsdata = (void *) time;
+	if (!RB_EMPTY_NODE(&fd->node)) {
+		rb_erase(&fd->node, &bucket->tree);
+		RB_CLEAR_NODE(&fd->node);
+	}
 }
 
-static inline u64 fuse_dentry_time(const struct dentry *entry)
+static void fuse_dentry_tree_del_node(struct dentry *dentry)
 {
-	return (u64)entry->d_fsdata;
+	struct fuse_dentry *fd = dentry->d_fsdata;
+	struct dentry_bucket *bucket = get_dentry_bucket(dentry);
+
+	spin_lock(&bucket->lock);
+	__fuse_dentry_tree_del_node(fd, bucket);
+	spin_unlock(&bucket->lock);
 }
 
-#else
-union fuse_dentry {
-	u64 time;
-	struct rcu_head rcu;
-};
+static void fuse_dentry_tree_add_node(struct dentry *dentry)
+{
+	struct fuse_dentry *fd = dentry->d_fsdata;
+	struct dentry_bucket *bucket;
+	struct fuse_dentry *cur;
+	struct rb_node **p, *parent = NULL;
+
+	if (!inval_wq)
+		return;
+
+	bucket = get_dentry_bucket(dentry);
+
+	spin_lock(&bucket->lock);
+
+	__fuse_dentry_tree_del_node(fd, bucket);
+
+	p = &bucket->tree.rb_node;
+	while (*p) {
+		parent = *p;
+		cur = rb_entry(*p, struct fuse_dentry, node);
+		if (fd->time < cur->time)
+			p = &(*p)->rb_left;
+		else
+			p = &(*p)->rb_right;
+	}
+	rb_link_node(&fd->node, parent, p);
+	rb_insert_color(&fd->node, &bucket->tree);
+	spin_unlock(&bucket->lock);
+}
+
+/*
+ * work queue which, when enabled, will periodically check for expired dentries
+ * in the dentries tree.
+ */
+static void fuse_dentry_tree_work(struct work_struct *work)
+{
+	LIST_HEAD(dispose);
+	struct fuse_dentry *fd;
+	struct rb_node *node;
+	int i;
+
+	for (i = 0; i < HASH_SIZE; i++) {
+		spin_lock(&dentry_hash[i].lock);
+		node = rb_first(&dentry_hash[i].tree);
+		while (node) {
+			fd = rb_entry(node, struct fuse_dentry, node);
+			if (time_after64(get_jiffies_64(), fd->time)) {
+				rb_erase(&fd->node, &dentry_hash[i].tree);
+				RB_CLEAR_NODE(&fd->node);
+				spin_unlock(&dentry_hash[i].lock);
+				d_dispose_if_unused(fd->dentry, &dispose);
+				cond_resched();
+				spin_lock(&dentry_hash[i].lock);
+			} else
+				break;
+			node = rb_first(&dentry_hash[i].tree);
+		}
+		spin_unlock(&dentry_hash[i].lock);
+		shrink_dentry_list(&dispose);
+	}
+
+	if (inval_wq)
+		schedule_delayed_work(&dentry_tree_work,
+				      secs_to_jiffies(inval_wq));
+}
+
+void fuse_dentry_tree_init(void)
+{
+	int i;
+
+	for (i = 0; i < HASH_SIZE; i++) {
+		spin_lock_init(&dentry_hash[i].lock);
+		dentry_hash[i].tree = RB_ROOT;
+	}
+	INIT_DELAYED_WORK(&dentry_tree_work, fuse_dentry_tree_work);
+}
+
+void fuse_dentry_tree_cleanup(void)
+{
+	int i;
+
+	inval_wq = 0;
+	cancel_delayed_work_sync(&dentry_tree_work);
+
+	for (i = 0; i < HASH_SIZE; i++)
+		WARN_ON_ONCE(!RB_EMPTY_ROOT(&dentry_hash[i].tree));
+}
 
 static inline void __fuse_dentry_settime(struct dentry *dentry, u64 time)
 {
-	((union fuse_dentry *) dentry->d_fsdata)->time = time;
+	((struct fuse_dentry *) dentry->d_fsdata)->time = time;
 }
 
 static inline u64 fuse_dentry_time(const struct dentry *entry)
 {
-	return ((union fuse_dentry *) entry->d_fsdata)->time;
+	return ((struct fuse_dentry *) entry->d_fsdata)->time;
 }
-#endif
 
 static void fuse_dentry_settime(struct dentry *dentry, u64 time)
 {
@@ -81,6 +240,7 @@ static void fuse_dentry_settime(struct dentry *dentry, u64 time)
 	}
 
 	__fuse_dentry_settime(dentry, time);
+	fuse_dentry_tree_add_node(dentry);
 }
 
 /*
@@ -283,21 +443,36 @@ static int fuse_dentry_revalidate(struct inode *dir, const struct qstr *name,
 	goto out;
 }
 
-#if BITS_PER_LONG < 64
 static int fuse_dentry_init(struct dentry *dentry)
 {
-	dentry->d_fsdata = kzalloc(sizeof(union fuse_dentry),
-				   GFP_KERNEL_ACCOUNT | __GFP_RECLAIMABLE);
+	struct fuse_dentry *fd;
 
-	return dentry->d_fsdata ? 0 : -ENOMEM;
+	fd = kzalloc(sizeof(struct fuse_dentry),
+			  GFP_KERNEL_ACCOUNT | __GFP_RECLAIMABLE);
+	if (!fd)
+		return -ENOMEM;
+
+	fd->dentry = dentry;
+	RB_CLEAR_NODE(&fd->node);
+	dentry->d_fsdata = fd;
+
+	return 0;
+}
+
+static void fuse_dentry_prune(struct dentry *dentry)
+{
+	struct fuse_dentry *fd = dentry->d_fsdata;
+
+	if (!RB_EMPTY_NODE(&fd->node))
+		fuse_dentry_tree_del_node(dentry);
 }
+
 static void fuse_dentry_release(struct dentry *dentry)
 {
-	union fuse_dentry *fd = dentry->d_fsdata;
+	struct fuse_dentry *fd = dentry->d_fsdata;
 
 	kfree_rcu(fd, rcu);
 }
-#endif
 
 static int fuse_dentry_delete(const struct dentry *dentry)
 {
@@ -331,10 +506,9 @@ static struct vfsmount *fuse_dentry_automount(struct path *path)
 const struct dentry_operations fuse_dentry_operations = {
 	.d_revalidate	= fuse_dentry_revalidate,
 	.d_delete	= fuse_dentry_delete,
-#if BITS_PER_LONG < 64
 	.d_init		= fuse_dentry_init,
+	.d_prune	= fuse_dentry_prune,
 	.d_release	= fuse_dentry_release,
-#endif
 	.d_automount	= fuse_dentry_automount,
 };
 
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index cc428d04be3e..b34be6f95bbe 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -54,6 +54,13 @@
 /** Frequency (in jiffies) of request timeout checks, if opted into */
 extern const unsigned long fuse_timeout_timer_freq;
 
+/*
+ * Dentries invalidation workqueue period, in seconds.  The value of this
+ * parameter shall be >= FUSE_DENTRY_INVAL_FREQ_MIN seconds, or 0 (zero), in
+ * which case no workqueue will be created.
+ */
+extern unsigned inval_wq __read_mostly;
+
 /** Maximum of max_pages received in init_out */
 extern unsigned int fuse_max_pages_limit;
 /*
@@ -1266,6 +1273,9 @@ void fuse_wait_aborted(struct fuse_conn *fc);
 /* Check if any requests timed out */
 void fuse_check_timeout(struct work_struct *work);
 
+void fuse_dentry_tree_init(void);
+void fuse_dentry_tree_cleanup(void);
+
 /**
  * Invalidate inode attributes
  */
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 7ddfd2b3cc9c..db275a04021d 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -2256,6 +2256,8 @@ static int __init fuse_init(void)
 	if (res)
 		goto err_sysfs_cleanup;
 
+	fuse_dentry_tree_init();
+
 	sanitize_global_limit(&max_user_bgreq);
 	sanitize_global_limit(&max_user_congthresh);
 
@@ -2275,6 +2277,7 @@ static void __exit fuse_exit(void)
 {
 	pr_debug("exit\n");
 
+	fuse_dentry_tree_cleanup();
 	fuse_ctl_cleanup();
 	fuse_sysfs_cleanup();
 	fuse_fs_cleanup();

[RFC PATCH v6 3/4] fuse: new work queue to invalidate dentries from old epochs

[Luis Henriques]

With the infrastructure introduced to periodically invalidate expired
dentries, it is now possible to add an extra work queue to invalidate
dentries when an epoch is incremented.  This work queue will only be
triggered when the 'inval_wq' parameter is set.

Signed-off-by: Luis Henriques <luis@igalia.com>
---
 fs/fuse/dev.c    |  7 ++++---
 fs/fuse/dir.c    | 21 +++++++++++++++++++++
 fs/fuse/fuse_i.h |  4 ++++
 fs/fuse/inode.c  |  2 ++
 4 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 5150aa25e64b..c24e78f86b50 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -2033,13 +2033,14 @@ static int fuse_notify_resend(struct fuse_conn *fc)
 
 /*
  * Increments the fuse connection epoch.  This will result of dentries from
- * previous epochs to be invalidated.
- *
- * XXX optimization: add call to shrink_dcache_sb()?
+ * previous epochs to be invalidated.  Additionally, if inval_wq is set, a work
+ * queue is scheduled to trigger the invalidation.
  */
 static int fuse_notify_inc_epoch(struct fuse_conn *fc)
 {
 	atomic_inc(&fc->epoch);
+	if (inval_wq)
+		schedule_work(&fc->epoch_work);
 
 	return 0;
 }
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 3e88da803ba6..67e3340a443c 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -189,6 +189,27 @@ static void fuse_dentry_tree_work(struct work_struct *work)
 				      secs_to_jiffies(inval_wq));
 }
 
+void fuse_epoch_work(struct work_struct *work)
+{
+	struct fuse_conn *fc = container_of(work, struct fuse_conn,
+					    epoch_work);
+	struct fuse_mount *fm;
+	struct inode *inode;
+
+	down_read(&fc->killsb);
+
+	inode = fuse_ilookup(fc, FUSE_ROOT_ID, &fm);
+	iput(inode);
+
+	if (fm) {
+		/* Remove all possible active references to cached inodes */
+		shrink_dcache_sb(fm->sb);
+	} else
+		pr_warn("Failed to get root inode");
+
+	up_read(&fc->killsb);
+}
+
 void fuse_dentry_tree_init(void)
 {
 	int i;
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index b34be6f95bbe..53ca87814ef3 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -649,6 +649,8 @@ struct fuse_conn {
 	/** Current epoch for up-to-date dentries */
 	atomic_t epoch;
 
+	struct work_struct epoch_work;
+
 	struct rcu_head rcu;
 
 	/** The user id for this mount */
@@ -1276,6 +1278,8 @@ void fuse_check_timeout(struct work_struct *work);
 void fuse_dentry_tree_init(void);
 void fuse_dentry_tree_cleanup(void);
 
+void fuse_epoch_work(struct work_struct *work);
+
 /**
  * Invalidate inode attributes
  */
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index db275a04021d..c054f02e661d 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -967,6 +967,7 @@ void fuse_conn_init(struct fuse_conn *fc, struct fuse_mount *fm,
 	refcount_set(&fc->count, 1);
 	atomic_set(&fc->dev_count, 1);
 	atomic_set(&fc->epoch, 1);
+	INIT_WORK(&fc->epoch_work, fuse_epoch_work);
 	init_waitqueue_head(&fc->blocked_waitq);
 	fuse_iqueue_init(&fc->iq, fiq_ops, fiq_priv);
 	INIT_LIST_HEAD(&fc->bg_queue);
@@ -1019,6 +1020,7 @@ void fuse_conn_put(struct fuse_conn *fc)
 			fuse_dax_conn_free(fc);
 		if (fc->timeout.req_timeout)
 			cancel_delayed_work_sync(&fc->timeout.work);
+		cancel_work_sync(&fc->epoch_work);
 		if (fiq->ops->release)
 			fiq->ops->release(fiq);
 		put_pid_ns(fc->pid_ns);

[RFC PATCH v6 4/4] fuse: refactor fuse_conn_put() to remove negative logic.

[Luis Henriques]

There is no functional change with this patch.  It simply refactors
function fuse_conn_put() to not use negative logic, which makes it more
easier to read.

Signed-off-by: Luis Henriques <luis@igalia.com>
---
 fs/fuse/inode.c | 41 +++++++++++++++++++++--------------------
 1 file changed, 21 insertions(+), 20 deletions(-)

diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index c054f02e661d..80cce3bb6b00 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1012,27 +1012,28 @@ static void delayed_release(struct rcu_head *p)
 
 void fuse_conn_put(struct fuse_conn *fc)
 {
-	if (refcount_dec_and_test(&fc->count)) {
-		struct fuse_iqueue *fiq = &fc->iq;
-		struct fuse_sync_bucket *bucket;
-
-		if (IS_ENABLED(CONFIG_FUSE_DAX))
-			fuse_dax_conn_free(fc);
-		if (fc->timeout.req_timeout)
-			cancel_delayed_work_sync(&fc->timeout.work);
-		cancel_work_sync(&fc->epoch_work);
-		if (fiq->ops->release)
-			fiq->ops->release(fiq);
-		put_pid_ns(fc->pid_ns);
-		bucket = rcu_dereference_protected(fc->curr_bucket, 1);
-		if (bucket) {
-			WARN_ON(atomic_read(&bucket->count) != 1);
-			kfree(bucket);
-		}
-		if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
-			fuse_backing_files_free(fc);
-		call_rcu(&fc->rcu, delayed_release);
+	struct fuse_iqueue *fiq = &fc->iq;
+	struct fuse_sync_bucket *bucket;
+
+	if (!refcount_dec_and_test(&fc->count))
+		return;
+
+	if (IS_ENABLED(CONFIG_FUSE_DAX))
+		fuse_dax_conn_free(fc);
+	if (fc->timeout.req_timeout)
+		cancel_delayed_work_sync(&fc->timeout.work);
+	cancel_work_sync(&fc->epoch_work);
+	if (fiq->ops->release)
+		fiq->ops->release(fiq);
+	put_pid_ns(fc->pid_ns);
+	bucket = rcu_dereference_protected(fc->curr_bucket, 1);
+	if (bucket) {
+		WARN_ON(atomic_read(&bucket->count) != 1);
+		kfree(bucket);
 	}
+	if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
+		fuse_backing_files_free(fc);
+	call_rcu(&fc->rcu, delayed_release);
 }
 EXPORT_SYMBOL_GPL(fuse_conn_put);
 

Re: [RFC PATCH v6 0/4] fuse: work queues to invalided dentries

[Luis Henriques]

Hey Miklos,

On Tue, Sep 16 2025, Luis Henriques wrote:

> Hi Miklos,
>
> Here's a new version of the patchset to invalidate expired dentries.  Most
> of the changes (and there are a lot of them!) result from the v5 review.
> See below for details.

Just a gentle ping to make sure it doesn't fall through the cracks.

Cheers,
-- 
Luís


> Changes since v5:
>
> - Changes to dcache: export shrink_dentry_list() and add new helper
>   d_dispose_if_unused()
> - Reduced hash lock array size
> - Set 'inval_wq' max value to USHRT_MAX to prevent a potential overflow in
>   secs_to_jiffies()
> - Updated 'inval_wq' parameter description and comment
> - Removed useless check in fuse_dentry_tree_del_node()
> - Make fuse_dentry_tree_work() use dcache helpers d_dispose_if_unused() and
>   shrink_dentry_list()
> - Fix usage of need_resched() (replaced with cond_resched())
> - fuse_dentry_tree_cleanup() now simply does a WARN_ON() if there are
>   non-empty trees
> - Removed TODO comment in fuse_conn_destroy() -- no need to prune trees
> - Have fuse_epoch_work() use of shrink_dcache_sb() instead of going through
>   all the trees
> - Refactor fuse_conn_put() in a separate patch
> - Fix bug in fuse_dentry_tree_add_node() for cases where dentries have the
>   same timeout
> - Reword some of the commits text
>
> Changes since v4:
>  
> - Dropped extra check in fuse_dentry_tree_add_node() (Chunsheng)
> - Make the dentries trees global instead of per fuse_conn (Miklos)
> - Protect trees with hashed locking instead of a single lock (Miklos)
> - Added new work queue (2nd patch) specifically to handle epoch (Miklos)
>  
> Changes since v3:
>  
> - Use of need_resched() instead of limiting the work queue to run for 5
>   seconds
> - Restore usage of union with rcu_head, in struct fuse_dentry
> - Minor changes in comments (e.g. s/workqueue/work queue/)
>  
> Changes since v2:
>  
> - Major rework, the dentries tree nodes are now in fuse_dentry and they are
>   tied to the actual dentry lifetime
> - Mount option is now a module parameter
> - workqueue now runs for at most 5 seconds before rescheduling
>
> Luis Henriques (4):
>   dcache: export shrink_dentry_list() and new helper
>     d_dispose_if_unused()
>   fuse: new work queue to periodically invalidate expired dentries
>   fuse: new work queue to invalidate dentries from old epochs
>   fuse: refactor fuse_conn_put() to remove negative logic.
>
>  fs/dcache.c            |  18 ++--
>  fs/fuse/dev.c          |   7 +-
>  fs/fuse/dir.c          | 237 +++++++++++++++++++++++++++++++++++++----
>  fs/fuse/fuse_i.h       |  14 +++
>  fs/fuse/inode.c        |  44 ++++----
>  include/linux/dcache.h |   2 +
>  6 files changed, 273 insertions(+), 49 deletions(-)
>

Re: [RFC PATCH v6 0/4] fuse: work queues to invalided dentries

[Miklos Szeredi]

On Tue, 16 Sept 2025 at 15:53, Luis Henriques <luis@igalia.com> wrote:
>
> Hi Miklos,
>
> Here's a new version of the patchset to invalidate expired dentries.  Most
> of the changes (and there are a lot of them!) result from the v5 review.
> See below for details.

Applied, thanks.

Miklos

Re: [RFC PATCH v6 0/4] fuse: work queues to invalided dentries

[Luis Henriques]

On Thu, Nov 13 2025, Miklos Szeredi wrote:

> On Tue, 16 Sept 2025 at 15:53, Luis Henriques <luis@igalia.com> wrote:
>>
>> Hi Miklos,
>>
>> Here's a new version of the patchset to invalidate expired dentries.  Most
>> of the changes (and there are a lot of them!) result from the v5 review.
>> See below for details.
>
> Applied, thanks.

That's awesome, thanks a lot Miklos!

Cheers,
-- 
Luís