AI Trajectory

null

{
  "EnableConfigs": [
    "FUSE_FS"
  ],
  "FocusSymbols": [
    "fuse_dev_flush",
    "fuse_dev_release",
    "fuse_get_dev",
    "__fuse_get_dev"
  ],
  "Reasoning": "The patch modifies the core FUSE device file operations to handle final close (flush) and release, introducing a new state FUSE_DEV_CHAN_DISCONNECTED. This is a functional change in reachable core kernel logic and should be fuzzed to ensure no race conditions or use-after-free issues occur during FUSE device teardown.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit 5ef12397dcf3dbb519b3745124fa9dc892223091\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Fri Jul 24 16:47:58 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/fs/fuse/dev.c b/fs/fuse/dev.c\nindex 5763a7cd3b37fa..8b14c7d57a0119 100644\n--- a/fs/fuse/dev.c\n+++ b/fs/fuse/dev.c\n@@ -1662,18 +1662,23 @@ static int fuse_dev_open(struct inode *inode, struct file *file)\n struct fuse_dev *fuse_get_dev(struct file *file)\n {\n \tstruct fuse_dev *fud = fuse_file_to_fud(file);\n+\tstruct fuse_chan *fch = fuse_dev_chan_get(fud);\n \tint err;\n \n-\tif (unlikely(!fuse_dev_chan_get(fud))) {\n+\tif (unlikely(!fch)) {\n \t\t/* only block waiting for mount if sync init was requested */\n \t\tif (!fud-\u003esync_init)\n \t\t\treturn ERR_PTR(-EPERM);\n \n-\t\terr = wait_event_interruptible(fuse_dev_waitq, fuse_dev_chan_get(fud) != NULL);\n+\t\terr = wait_event_interruptible(fuse_dev_waitq,\n+\t\t\t\t\t       (fch = fuse_dev_chan_get(fud)) != NULL);\n \t\tif (err)\n \t\t\treturn ERR_PTR(err);\n \t}\n \n+\tif (unlikely(fch == FUSE_DEV_CHAN_DISCONNECTED))\n+\t\treturn ERR_PTR(-EPERM);\n+\n \treturn fud;\n }\n \n@@ -2211,17 +2216,31 @@ void fuse_chan_wait_aborted(struct fuse_chan *fch)\n \tfuse_uring_wait_stopped_queues(fch);\n }\n \n+static bool fuse_dev_all_closing(struct fuse_chan *fch)\n+{\n+\tstruct fuse_dev *pos;\n+\n+\tlockdep_assert_held(\u0026fch-\u003elock);\n+\n+\tlist_for_each_entry(pos, \u0026fch-\u003edevices, entry) {\n+\t\tif (!pos-\u003eclosing)\n+\t\t\treturn false;\n+\t}\n+\treturn true;\n+}\n+\n int fuse_dev_release(struct inode *inode, struct file *file)\n {\n \tstruct fuse_dev *fud = fuse_file_to_fud(file);\n \t/* Pairs with cmpxchg() in fuse_dev_install() */\n \tstruct fuse_chan *fch = xchg(\u0026fud-\u003echan, FUSE_DEV_CHAN_DISCONNECTED);\n \n-\tif (fch) {\n+\tif (fch \u0026\u0026 fch != FUSE_DEV_CHAN_DISCONNECTED) {\n \t\tstruct fuse_pqueue *fpq = \u0026fud-\u003epq;\n \t\tLIST_HEAD(to_end);\n \t\tunsigned int i;\n \t\tbool last;\n+\t\tbool abort;\n \n \t\t/* Make sure fuse_dev_install_with_pq() has finished */\n \t\tspin_lock(\u0026fch-\u003elock);\n@@ -2234,14 +2253,15 @@ int fuse_dev_release(struct inode *inode, struct file *file)\n \t\tlist_del(\u0026fud-\u003eentry);\n \t\t/* Are we the last open device? */\n \t\tlast = list_empty(\u0026fch-\u003edevices);\n+\t\tabort = fch-\u003econnected \u0026\u0026 fuse_dev_all_closing(fch);\n \t\tspin_unlock(\u0026fch-\u003elock);\n \n \t\tfuse_dev_end_requests(\u0026to_end);\n \n-\t\tif (last) {\n+\t\tif (last)\n \t\t\tWARN_ON(fch-\u003eiq.fasync != NULL);\n+\t\tif (abort)\n \t\t\tfuse_chan_abort(fch, false);\n-\t\t}\n \t\tfuse_conn_put(fch-\u003econn);\n \t}\n \tfuse_dev_put(fud);\n@@ -2375,6 +2395,34 @@ static void fuse_dev_show_fdinfo(struct seq_file *seq, struct file *file)\n }\n #endif\n \n+static int fuse_dev_flush(struct file *file, fl_owner_t id)\n+{\n+\tstruct fuse_dev *fud = fuse_file_to_fud(file);\n+\tstruct fuse_chan *fch;\n+\tbool abort;\n+\n+\tif (file_count(file) != 1)\n+\t\treturn 0;\n+\n+\t/*\n+\t * Atomically transition fud-\u003echan from NULL to FUSE_DEV_CHAN_DISCONNECTED\n+\t * on final close to prevent a later fuse_dev_install() from succeeding.\n+\t */\n+\tfch = cmpxchg(\u0026fud-\u003echan, NULL, FUSE_DEV_CHAN_DISCONNECTED);\n+\tif (!fch || fch == FUSE_DEV_CHAN_DISCONNECTED)\n+\t\treturn 0;\n+\n+\tspin_lock(\u0026fch-\u003elock);\n+\tfud-\u003eclosing = true;\n+\tabort = fch-\u003econnected \u0026\u0026 fuse_dev_all_closing(fch);\n+\tspin_unlock(\u0026fch-\u003elock);\n+\n+\tif (abort)\n+\t\tfuse_chan_abort(fch, false);\n+\n+\treturn 0;\n+}\n+\n const struct file_operations fuse_dev_operations = {\n \t.owner\t\t= THIS_MODULE,\n \t.open\t\t= fuse_dev_open,\n@@ -2383,6 +2431,7 @@ const struct file_operations fuse_dev_operations = {\n \t.write_iter\t= fuse_dev_write,\n \t.splice_write\t= fuse_dev_splice_write,\n \t.poll\t\t= fuse_dev_poll,\n+\t.flush\t\t= fuse_dev_flush,\n \t.release\t= fuse_dev_release,\n \t.fasync\t\t= fuse_dev_fasync,\n \t.unlocked_ioctl = fuse_dev_ioctl,\ndiff --git a/fs/fuse/fuse_dev_i.h b/fs/fuse/fuse_dev_i.h\nindex 668c8391d61c03..e484be17da8614 100644\n--- a/fs/fuse/fuse_dev_i.h\n+++ b/fs/fuse/fuse_dev_i.h\n@@ -302,6 +302,9 @@ struct fuse_dev {\n \t/** @sync_init: Issue FUSE_INIT synchronously */\n \tbool sync_init;\n \n+\t/** @closing: Final close has started, protected by chan-\u003elock */\n+\tbool closing;\n+\n \t/** @chan: Fuse channel for this device */\n \tstruct fuse_chan *chan;\n \n@@ -337,9 +340,17 @@ struct fuse_copy_state {\n  * Lockless access is OK, because fud-\u003echan is set once during mount and is valid\n  * until the file is released.\n  *\n- * fud-\u003echan is set to FUSE_DEV_CHAN_DISCONNECTED only after the containing file is\n- * released, so result is safe to dereference in most cases.  Exceptions are:\n- * fuse_dev_put() and fuse_fill_super_common().\n+ * fud-\u003echan can have three states:\n+ * - NULL: device is not installed yet\n+ * - valid pointer: device is installed\n+ * - FUSE_DEV_CHAN_DISCONNECTED: device is released\n+ *\n+ * Final flush replaces NULL with the disconnected sentinel only for an\n+ * uninstalled device, while for an installed device, flush leaves the channel\n+ * pointer intact and records closing, and release later installs the sentinel.\n+ * Thus the result is safe to dereference in most cases.  Exceptions are:\n+ * fuse_dev_put() and fuse_fill_super_common(). fuse_get_dev() and\n+ * __fuse_get_dev() reject the sentinel.\n  */\n static inline struct fuse_chan *fuse_dev_chan_get(struct fuse_dev *fud)\n {\n@@ -355,8 +366,9 @@ static inline struct fuse_dev *fuse_file_to_fud(struct file *file)\n static inline struct fuse_dev *__fuse_get_dev(struct file *file)\n {\n \tstruct fuse_dev *fud = fuse_file_to_fud(file);\n+\tstruct fuse_chan *fch = fuse_dev_chan_get(fud);\n \n-\tif (!fuse_dev_chan_get(fud))\n+\tif (!fch || fch == FUSE_DEV_CHAN_DISCONNECTED)\n \t\treturn NULL;\n \n \treturn fud;\n"
}

best-expensive

null

{
  "EnableConfigs": [
    "FUSE_FS"
  ],
  "FocusSymbols": [
    "fuse_dev_flush",
    "fuse_dev_release",
    "fuse_get_dev",
    "__fuse_get_dev"
  ],
  "Reasoning": "The patch modifies the core FUSE device file operations to handle final close (flush) and release, introducing a new state FUSE_DEV_CHAN_DISCONNECTED. This is a functional change in reachable core kernel logic and should be fuzzed to ensure no race conditions or use-after-free issues occur during FUSE device teardown.",
  "WorthFuzzing": true
}

You are an expert Linux kernel maintainer.
Your job is to review a provided patch series and determine
if it makes functional changes to the kernel that should be fuzzed.

IMPORTANT: The changes have ALREADY been applied and committed as the HEAD commit in
your workspace. Do NOT rely on your internal knowledge of the kernel. You must actively
use your code access tools to examine the actual source code and confirm any assumptions.

Return WorthFuzzing=false if the patch only contains:
- Modifications to Documentation/, Kconfig files, or code comments.
- Purely decorative changes, such as logging (e.g., pr_err, printk) or tracepoints.
- Changes to numeric constants or macros that do not functionally alter execution flow.
- Code paths that are impossible to reach in virtualized environments like GCE or QEMU,
even when utilizing software-emulated hardware (e.g., usb gadget, mac80211_hwsim).

If it modifies reachable core kernel logic, drivers, or architectures, use your code search
tools to verify the code can be executed, then return WorthFuzzing=true.

When returning WorthFuzzing=true, you MUST ALSO:
1. Extract any specific kernel functions that should be heavily fuzzed into FocusSymbols.
   Avoid listing generic hot-path functions to prevent skewed test distributions.
2. Identify any specific CONFIG_ options required to properly test this new/modified feature.
   Go and look into the Kconfig files and check for ifdefs around the code, do not make assumptions.
   Do not list too generic configs (we already have them enabled). Only list those that
   specifically cover the modified code. List them in the EnableConfigs output array,
   and DO NOT add a 'CONFIG_' prefix (e.g., return "NET_IPV4" instead of "CONFIG_NET_IPV4").
Prefer calling several tools at the same time to save round-trips.


Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.

For your convenience, here is the diff of the changes:
commit 5ef12397dcf3dbb519b3745124fa9dc892223091
Author: syz-cluster <triage@syzkaller.com>
Date:   Fri Jul 24 16:47:58 2026 +0000

    syz-cluster: applied patch under review

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 5763a7cd3b37fa..8b14c7d57a0119 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1662,18 +1662,23 @@ static int fuse_dev_open(struct inode *inode, struct file *file)
 struct fuse_dev *fuse_get_dev(struct file *file)
 {
 	struct fuse_dev *fud = fuse_file_to_fud(file);
+	struct fuse_chan *fch = fuse_dev_chan_get(fud);
 	int err;
 
-	if (unlikely(!fuse_dev_chan_get(fud))) {
+	if (unlikely(!fch)) {
 		/* only block waiting for mount if sync init was requested */
 		if (!fud->sync_init)
 			return ERR_PTR(-EPERM);
 
-		err = wait_event_interruptible(fuse_dev_waitq, fuse_dev_chan_get(fud) != NULL);
+		err = wait_event_interruptible(fuse_dev_waitq,
+					       (fch = fuse_dev_chan_get(fud)) != NULL);
 		if (err)
 			return ERR_PTR(err);
 	}
 
+	if (unlikely(fch == FUSE_DEV_CHAN_DISCONNECTED))
+		return ERR_PTR(-EPERM);
+
 	return fud;
 }
 
@@ -2211,17 +2216,31 @@ void fuse_chan_wait_aborted(struct fuse_chan *fch)
 	fuse_uring_wait_stopped_queues(fch);
 }
 
+static bool fuse_dev_all_closing(struct fuse_chan *fch)
+{
+	struct fuse_dev *pos;
+
+	lockdep_assert_held(&fch->lock);
+
+	list_for_each_entry(pos, &fch->devices, entry) {
+		if (!pos->closing)
+			return false;
+	}
+	return true;
+}
+
 int fuse_dev_release(struct inode *inode, struct file *file)
 {
 	struct fuse_dev *fud = fuse_file_to_fud(file);
 	/* Pairs with cmpxchg() in fuse_dev_install() */
 	struct fuse_chan *fch = xchg(&fud->chan, FUSE_DEV_CHAN_DISCONNECTED);
 
-	if (fch) {
+	if (fch && fch != FUSE_DEV_CHAN_DISCONNECTED) {
 		struct fuse_pqueue *fpq = &fud->pq;
 		LIST_HEAD(to_end);
 		unsigned int i;
 		bool last;
+		bool abort;
 
 		/* Make sure fuse_dev_install_with_pq() has finished */
 		spin_lock(&fch->lock);
@@ -2234,14 +2253,15 @@ int fuse_dev_release(struct inode *inode, struct file *file)
 		list_del(&fud->entry);
 		/* Are we the last open device? */
 		last = list_empty(&fch->devices);
+		abort = fch->connected && fuse_dev_all_closing(fch);
 		spin_unlock(&fch->lock);
 
 		fuse_dev_end_requests(&to_end);
 
-		if (last) {
+		if (last)
 			WARN_ON(fch->iq.fasync != NULL);
+		if (abort)
 			fuse_chan_abort(fch, false);
-		}
 		fuse_conn_put(fch->conn);
 	}
 	fuse_dev_put(fud);
@@ -2375,6 +2395,34 @@ static void fuse_dev_show_fdinfo(struct seq_file *seq, struct file *file)
 }
 #endif
 
+static int fuse_dev_flush(struct file *file, fl_owner_t id)
+{
+	struct fuse_dev *fud = fuse_file_to_fud(file);
+	struct fuse_chan *fch;
+	bool abort;
+
+	if (file_count(file) != 1)
+		return 0;
+
+	/*
+	 * Atomically transition fud->chan from NULL to FUSE_DEV_CHAN_DISCONNECTED
+	 * on final close to prevent a later fuse_dev_install() from succeeding.
+	 */
+	fch = cmpxchg(&fud->chan, NULL, FUSE_DEV_CHAN_DISCONNECTED);
+	if (!fch || fch == FUSE_DEV_CHAN_DISCONNECTED)
+		return 0;
+
+	spin_lock(&fch->lock);
+	fud->closing = true;
+	abort = fch->connected && fuse_dev_all_closing(fch);
+	spin_unlock(&fch->lock);
+
+	if (abort)
+		fuse_chan_abort(fch, false);
+
+	return 0;
+}
+
 const struct file_operations fuse_dev_operations = {
 	.owner		= THIS_MODULE,
 	.open		= fuse_dev_open,
@@ -2383,6 +2431,7 @@ const struct file_operations fuse_dev_operations = {
 	.write_iter	= fuse_dev_write,
 	.splice_write	= fuse_dev_splice_write,
 	.poll		= fuse_dev_poll,
+	.flush		= fuse_dev_flush,
 	.release	= fuse_dev_release,
 	.fasync		= fuse_dev_fasync,
 	.unlocked_ioctl = fuse_dev_ioctl,
diff --git a/fs/fuse/fuse_dev_i.h b/fs/fuse/fuse_dev_i.h
index 668c8391d61c03..e484be17da8614 100644
--- a/fs/fuse/fuse_dev_i.h
+++ b/fs/fuse/fuse_dev_i.h
@@ -302,6 +302,9 @@ struct fuse_dev {
 	/** @sync_init: Issue FUSE_INIT synchronously */
 	bool sync_init;
 
+	/** @closing: Final close has started, protected by chan->lock */
+	bool closing;
+
 	/** @chan: Fuse channel for this device */
 	struct fuse_chan *chan;
 
@@ -337,9 +340,17 @@ struct fuse_copy_state {
  * Lockless access is OK, because fud->chan is set once during mount and is valid
  * until the file is released.
  *
- * fud->chan is set to FUSE_DEV_CHAN_DISCONNECTED only after the containing file is
- * released, so result is safe to dereference in most cases.  Exceptions are:
- * fuse_dev_put() and fuse_fill_super_common().
+ * fud->chan can have three states:
+ * - NULL: device is not installed yet
+ * - valid pointer: device is installed
+ * - FUSE_DEV_CHAN_DISCONNECTED: device is released
+ *
+ * Final flush replaces NULL with the disconnected sentinel only for an
+ * uninstalled device, while for an installed device, flush leaves the channel
+ * pointer intact and records closing, and release later installs the sentinel.
+ * Thus the result is safe to dereference in most cases.  Exceptions are:
+ * fuse_dev_put() and fuse_fill_super_common(). fuse_get_dev() and
+ * __fuse_get_dev() reject the sentinel.
  */
 static inline struct fuse_chan *fuse_dev_chan_get(struct fuse_dev *fud)
 {
@@ -355,8 +366,9 @@ static inline struct fuse_dev *fuse_file_to_fud(struct file *file)
 static inline struct fuse_dev *__fuse_get_dev(struct file *file)
 {
 	struct fuse_dev *fud = fuse_file_to_fud(file);
+	struct fuse_chan *fch = fuse_dev_chan_get(fud);
 
-	if (!fuse_dev_chan_get(fud))
+	if (!fch || fch == FUSE_DEV_CHAN_DISCONNECTED)
 		return NULL;
 
 	return fud;

gemini-3.1-pro-preview

null

null

							input: 3824
							output: 29
							thoughts: 232
						

**Analyzing a FUSE Patch**

Okay, so I'm looking at this patch that tweaks the FUSE subsystem. It's touching `fs/fuse/dev.c` and `fs/fuse/fuse_dev_i.h`, which immediately flags this as a potentially significant functional change. The core of it seems to be adding a `flush` operation (`fuse_dev_flush`) to the `fuse_dev_operations` struct.  That's interesting - dealing with flushing at the device level implies more robust resource management on close. The patch also modifies `fuse_get_dev`, `fuse_dev_release`, and `__fuse_get_dev` to account for `FUSE_DEV_CHAN_DISCONNECTED`, which likely means they are handling channel disconnection events more gracefully now. The introduction of `fuse_dev_all_closing` and a `closing` boolean within `struct fuse_dev` further reinforces the focus on handling device closure and ensuring operations are completed correctly before shutdown. Given the nature of these changes, I'd say this patch warrants some serious fuzzing to test it thoroughly.

Now, let me just confirm which config options are relevant here, so I can ensure the tests are properly configured. I'm pretty sure `CONFIG_FUSE_FS` is the primary one, but I want to be sure that there aren't any subsidiary configuration options that control aspects of these flush operations or device disconnection handling. I'll need to double check `fs/fuse/dev.c` and `fs/fuse/fuse_dev_i.h` directly for any specific configurations using `grepper` and look for instances of `CONFIG_`. Just a quick scan to make certain.

{
  "Expression": "CONFIG_",
  "PathPrefix": "fs/fuse/dev.c"
}

{
  "Output": "fs/fuse/dev.c=809=ssize_t fuse_chan_send(struct fuse_chan *fch, struct fuse_args *args)\n--\nfs/fuse/dev.c-843-\nfs/fuse/dev.c:844:#ifdef CONFIG_FUSE_IO_URING\nfs/fuse/dev.c-845-static bool fuse_request_queue_background_uring(struct fuse_req *req)\n--\nfs/fuse/dev.c=861=static int fuse_request_queue_background(struct fuse_req *req)\n--\nfs/fuse/dev.c-872-\nfs/fuse/dev.c:873:#ifdef CONFIG_FUSE_IO_URING\nfs/fuse/dev.c-874-\tif (fuse_uring_ready(fch))\n--\nfs/fuse/dev.c=2318=static long fuse_dev_ioctl_backing_open(struct file *file,\n--\nfs/fuse/dev.c-2326-\nfs/fuse/dev.c:2327:\tif (!IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))\nfs/fuse/dev.c-2328-\t\treturn -EOPNOTSUPP;\n--\nfs/fuse/dev.c=2336=static long fuse_dev_ioctl_backing_close(struct file *file, __u32 __user *argp)\n--\nfs/fuse/dev.c-2343-\nfs/fuse/dev.c:2344:\tif (!IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))\nfs/fuse/dev.c-2345-\t\treturn -EOPNOTSUPP;\n--\nfs/fuse/dev.c=2364=static long fuse_dev_ioctl(struct file *file, unsigned int cmd,\n--\nfs/fuse/dev.c-2386-\nfs/fuse/dev.c:2387:#ifdef CONFIG_PROC_FS\nfs/fuse/dev.c-2388-static void fuse_dev_show_fdinfo(struct seq_file *seq, struct file *file)\n--\nfs/fuse/dev.c=2426=const struct file_operations fuse_dev_operations = {\n--\nfs/fuse/dev.c-2438-\t.compat_ioctl   = compat_ptr_ioctl,\nfs/fuse/dev.c:2439:#ifdef CONFIG_FUSE_IO_URING\nfs/fuse/dev.c-2440-\t.uring_cmd\t= fuse_uring_cmd,\nfs/fuse/dev.c-2441-#endif\nfs/fuse/dev.c:2442:#ifdef CONFIG_PROC_FS\nfs/fuse/dev.c-2443-\t.show_fdinfo\t= fuse_dev_show_fdinfo,\n"
}

gemini-3.1-pro-preview

null

null

							input: 5156
							output: 29
							thoughts: 78
						

Okay, here's my take on those thoughts, framed as my own reasoning:

**Analyzing the FUSE Device Driver Modification**

Right, so this patch is clearly digging into the heart of the FUSE device driver. It looks like it's touching `fuse_dev_flush`, `fuse_dev_release`, `fuse_get_dev`, and `__fuse_get_dev`. Those are critical functions – the bedrock of how FUSE interacts with the underlying block device, managing flushes, releases, and the acquisition of the device itself. Any change there is going to ripple outwards.

The author mentions `CONFIG_FUSE_FS`, which is the standard, primary configuration option for enabling the FUSE filesystem. But I know better than to just assume that's the only relevant configuration. To get the full picture and understand any dependencies or side effects of this change, I'm going to need to dig into the `fs/fuse/Kconfig` file. There could be conditional compilations or other configurations that impact how these functions behave and, therefore, the implications of this patch. Time to go deeper.

{
  "Expression": "config FUSE",
  "PathPrefix": "fs/fuse/Kconfig"
}

{
  "Output": "fs/fuse/Kconfig-1-# SPDX-License-Identifier: GPL-2.0-only\nfs/fuse/Kconfig:2:config FUSE_FS\nfs/fuse/Kconfig-3-\ttristate \"FUSE (Filesystem in Userspace) support\"\n--\nfs/fuse/Kconfig=32=config VIRTIO_FS\n--\nfs/fuse/Kconfig-42-\nfs/fuse/Kconfig:43:config FUSE_DAX\nfs/fuse/Kconfig-44-\tbool \"Virtio Filesystem Direct Host Memory Access support\"\n--\nfs/fuse/Kconfig-56-\nfs/fuse/Kconfig:57:config FUSE_PASSTHROUGH\nfs/fuse/Kconfig-58-\tbool \"FUSE passthrough operations support\"\n--\nfs/fuse/Kconfig-67-\nfs/fuse/Kconfig:68:config FUSE_IO_URING\nfs/fuse/Kconfig-69-\tbool \"FUSE communication over io-uring\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 5753
							output: 139
							thoughts: 389
						

**Analyzing the FUSE Device Handling Patch**

Okay, so looking at this patch, it's not specifically tied to those FUSE flags like `FUSE_DAX`, `FUSE_PASSTHROUGH`, or `FUSE_IO_URING`. It's going right into the heart of how the FUSE device itself is handled. That means `FUSE_FS` is the required config, obviously.

Now, my focus is going to be on these key symbols: `fuse_dev_flush`, `fuse_dev_release`, `fuse_get_dev`, `__fuse_get_dev`, and that static helper `fuse_dev_all_closing`. I want to see if `fuse_get_dev` and `__fuse_get_dev` are in any hot paths.

Hmm, let's see. `fuse_get_dev` is called from `fuse_dev_read`, `fuse_dev_write`, `fuse_dev_splice_read`, `fuse_dev_splice_write`, `fuse_dev_poll`, `fuse_dev_ioctl`, and `fuse_dev_fasync`. That's a lot of places. And `__fuse_get_dev` is only called by `fuse_dev_show_fdinfo`. `fuse_dev_flush` and `fuse_dev_release` are just file operations, and `fuse_dev_all_closing` is a static helper, so they seem less critical to start.

I'm thinking I'll include `fuse_dev_flush`, `fuse_dev_release`, `fuse_get_dev`, and `__fuse_get_dev` in my FocusSymbols.

Wait a second… `fuse_get_dev` is called on every single read/write to `/dev/fuse`? That *could* be a very hot path! But... the patch is specifically modifying how `fuse_get_dev` handles `FUSE_DEV_CHAN_DISCONNECTED`. Maybe that means that `fuse_dev_flush` and `fuse_dev_release` are the better focus here. I'll need to check the impact there. Okay, let's delve into those functions and see what we can find.

{
  "EnableConfigs": [
    "FUSE_FS"
  ],
  "FocusSymbols": [
    "fuse_dev_flush",
    "fuse_dev_release",
    "fuse_get_dev",
    "__fuse_get_dev"
  ],
  "Reasoning": "The patch modifies the core FUSE device file operations to handle final close (flush) and release, introducing a new state FUSE_DEV_CHAN_DISCONNECTED. This is a functional change in reachable core kernel logic and should be fuzzed to ensure no race conditions or use-after-free issues occur during FUSE device teardown.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "FUSE_FS"
  ],
  "FocusSymbols": [
    "fuse_dev_flush",
    "fuse_dev_release",
    "fuse_get_dev",
    "__fuse_get_dev"
  ],
  "Reasoning": "The patch modifies the core FUSE device file operations to handle final close (flush) and release, introducing a new state FUSE_DEV_CHAN_DISCONNECTED. This is a functional change in reachable core kernel logic and should be fuzzed to ensure no race conditions or use-after-free issues occur during FUSE device teardown.",
  "WorthFuzzing": true
}