AI Trajectory

null

{
  "EnableConfigs": [
    "FUSE_IO_URING"
  ],
  "FocusSymbols": [
    "fuse_uring_task_to_queue",
    "fuse_uring_queue_fuse_req",
    "fuse_uring_queue_bq_req",
    "fuse_uring_find_avail_queue"
  ],
  "Reasoning": "The patch modifies the FUSE io-uring communication logic to find an available queue when the current task's queue has no available entries. This is a functional change in the FUSE subsystem that can be reached by using FUSE over io-uring.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit f675aab44296a0e461f8bb8dcff7435c7f6681a5\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Tue Jul 14 10:18:43 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c\nindex 77c8cec43d9c65..c36438e79f8d16 100644\n--- a/fs/fuse/dev_uring.c\n+++ b/fs/fuse/dev_uring.c\n@@ -11,6 +11,7 @@\n \n #include \u003clinux/fs.h\u003e\n #include \u003clinux/io_uring/cmd.h\u003e\n+#include \u003clinux/topology.h\u003e\n \n static bool __read_mostly enable_uring;\n module_param(enable_uring, bool, 0644);\n@@ -1318,10 +1319,46 @@ static void fuse_uring_send_in_task(struct io_tw_req tw_req, io_tw_token_t tw)\n \t}\n }\n \n+static inline bool fuse_uring_queue_has_avail_ent(struct fuse_ring_queue *queue)\n+{\n+\tbool has;\n+\n+\tif (!queue)\n+\t\treturn false;\n+\n+\tspin_lock(\u0026queue-\u003elock);\n+\thas = !list_empty(\u0026queue-\u003eent_avail_queue);\n+\tspin_unlock(\u0026queue-\u003elock);\n+\n+\treturn has;\n+}\n+\n+static struct fuse_ring_queue *\n+fuse_uring_find_avail_queue(struct fuse_ring *ring, int node, unsigned int skip)\n+{\n+\tunsigned int i;\n+\tstruct fuse_ring_queue *queue;\n+\n+\tfor (i = 0; i \u003c ring-\u003enr_queues; i++) {\n+\n+\t\tif (i == skip)\n+\t\t\tcontinue;\n+\t\tif (node \u003e= 0 \u0026\u0026 cpu_to_node(i) != node)\n+\t\t\tcontinue;\n+\n+\t\tqueue = ring-\u003equeues[i];\n+\t\tif (fuse_uring_queue_has_avail_ent(queue))\n+\t\t\treturn queue;\n+\t}\n+\n+\treturn NULL;\n+}\n+\n static struct fuse_ring_queue *fuse_uring_task_to_queue(struct fuse_ring *ring)\n {\n \tunsigned int qid;\n \tstruct fuse_ring_queue *queue;\n+\tint node;\n \n \tqid = task_cpu(current);\n \n@@ -1331,7 +1368,15 @@ static struct fuse_ring_queue *fuse_uring_task_to_queue(struct fuse_ring *ring)\n \t\tqid = 0;\n \n \tqueue = ring-\u003equeues[qid];\n-\tWARN_ONCE(!queue, \"Missing queue for qid %d\\n\", qid);\n+\tif (fuse_uring_queue_has_avail_ent(queue))\n+\t\treturn queue;\n+\n+\tnode = cpu_to_node(qid);\n+\tqueue = fuse_uring_find_avail_queue(ring, node, qid);\n+\tif (!queue) {\n+\t\tqueue = ring-\u003equeues[qid];\n+\t\tWARN_ONCE(!queue, \"Missing queue for qid %d\\n\", qid);\n+\t}\n \n \treturn queue;\n }\n"
}

gemini-3.1-pro-preview

null

{
  "EnableConfigs": [
    "FUSE_IO_URING"
  ],
  "FocusSymbols": [
    "fuse_uring_task_to_queue",
    "fuse_uring_queue_fuse_req",
    "fuse_uring_queue_bq_req",
    "fuse_uring_find_avail_queue"
  ],
  "Reasoning": "The patch modifies the FUSE io-uring communication logic to find an available queue when the current task's queue has no available entries. This is a functional change in the FUSE subsystem that can be reached by using FUSE over io-uring.",
  "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 f675aab44296a0e461f8bb8dcff7435c7f6681a5
Author: syz-cluster <triage@syzkaller.com>
Date:   Tue Jul 14 10:18:43 2026 +0000

    syz-cluster: applied patch under review

diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
index 77c8cec43d9c65..c36438e79f8d16 100644
--- a/fs/fuse/dev_uring.c
+++ b/fs/fuse/dev_uring.c
@@ -11,6 +11,7 @@
 
 #include <linux/fs.h>
 #include <linux/io_uring/cmd.h>
+#include <linux/topology.h>
 
 static bool __read_mostly enable_uring;
 module_param(enable_uring, bool, 0644);
@@ -1318,10 +1319,46 @@ static void fuse_uring_send_in_task(struct io_tw_req tw_req, io_tw_token_t tw)
 	}
 }
 
+static inline bool fuse_uring_queue_has_avail_ent(struct fuse_ring_queue *queue)
+{
+	bool has;
+
+	if (!queue)
+		return false;
+
+	spin_lock(&queue->lock);
+	has = !list_empty(&queue->ent_avail_queue);
+	spin_unlock(&queue->lock);
+
+	return has;
+}
+
+static struct fuse_ring_queue *
+fuse_uring_find_avail_queue(struct fuse_ring *ring, int node, unsigned int skip)
+{
+	unsigned int i;
+	struct fuse_ring_queue *queue;
+
+	for (i = 0; i < ring->nr_queues; i++) {
+
+		if (i == skip)
+			continue;
+		if (node >= 0 && cpu_to_node(i) != node)
+			continue;
+
+		queue = ring->queues[i];
+		if (fuse_uring_queue_has_avail_ent(queue))
+			return queue;
+	}
+
+	return NULL;
+}
+
 static struct fuse_ring_queue *fuse_uring_task_to_queue(struct fuse_ring *ring)
 {
 	unsigned int qid;
 	struct fuse_ring_queue *queue;
+	int node;
 
 	qid = task_cpu(current);
 
@@ -1331,7 +1368,15 @@ static struct fuse_ring_queue *fuse_uring_task_to_queue(struct fuse_ring *ring)
 		qid = 0;
 
 	queue = ring->queues[qid];
-	WARN_ONCE(!queue, "Missing queue for qid %d\n", qid);
+	if (fuse_uring_queue_has_avail_ent(queue))
+		return queue;
+
+	node = cpu_to_node(qid);
+	queue = fuse_uring_find_avail_queue(ring, node, qid);
+	if (!queue) {
+		queue = ring->queues[qid];
+		WARN_ONCE(!queue, "Missing queue for qid %d\n", qid);
+	}
 
 	return queue;
 }

gemini-3.1-pro-preview

null

null

							input: 2408
							output: 23
							thoughts: 102
						

**Analyzing the FUSE dev_uring Patch**

Okay, so I'm looking at this patch that seems to be touching `fs/fuse/dev_uring.c`. My initial reaction is to quickly ascertain the context. Is this code even enabled in a standard configuration? I need to figure out what config options control the inclusion of this file. Knowing that will give me a first indication of how broadly applicable this change is.

Specifically, the patch seems to add two new functions: `fuse_uring_queue_has_avail_ent` and `fuse_uring_find_avail_queue`. Interesting. My understanding is that `dev_uring` is all about asynchronous I/O and user-space interaction. So, my gut feeling is that these functions likely deal with managing the queues involved in that asynchronous processing. I immediately want to understand *how* these new functions are interacting with existing structures.

The key modification appears to be in `fuse_uring_task_to_queue`. The patch is changing how we locate a queue. So, if the "current" queue doesn't have available entries, then this change is intended to find a *different* queue that does. This is potentially an important optimization. It is definitely worth exploring why the "current queue" might be full and when we might need to find an alternative. Is this solving a potential deadlock, load balancing issue, or just improving throughput? I have to dig deeper into the semantics of the `fuse_uring_task_to_queue` function itself to truly understand how this is used and improved.

{
  "Expression": "fuse_uring_task_to_queue"
}

{
  "Output": "fs/fuse/dev_uring.c=1337=fuse_uring_find_avail_queue(struct fuse_ring *ring, int node, unsigned int skip)\n--\nfs/fuse/dev_uring.c-1356-\nfs/fuse/dev_uring.c:1357:static struct fuse_ring_queue *fuse_uring_task_to_queue(struct fuse_ring *ring)\nfs/fuse/dev_uring.c-1358-{\n--\nfs/fuse/dev_uring.c=1393=void fuse_uring_queue_fuse_req(struct fuse_iqueue *fiq, struct fuse_req *req)\n--\nfs/fuse/dev_uring.c-1400-\terr = -EINVAL;\nfs/fuse/dev_uring.c:1401:\tqueue = fuse_uring_task_to_queue(ring);\nfs/fuse/dev_uring.c-1402-\tif (!queue)\n--\nfs/fuse/dev_uring.c=1435=bool fuse_uring_queue_bq_req(struct fuse_req *req)\n--\nfs/fuse/dev_uring.c-1441-\nfs/fuse/dev_uring.c:1442:\tqueue = fuse_uring_task_to_queue(ring);\nfs/fuse/dev_uring.c-1443-\tif (!queue)\n"
}

gemini-3.1-pro-preview

null

null

							input: 3215
							output: 27
							thoughts: 68
						

Here's my summary, as the expert:

**Tracing the Path of Uring Tasks in FUSE**

Okay, so I'm looking at how these FUSE requests are handled within the uring framework. My immediate thought is, I need to understand how `fuse_uring_task_to_queue` functions. I know it's called from both `fuse_uring_queue_fuse_req` and `fuse_uring_queue_bq_req`. That tells me these are the primary entry points for queuing requests to be processed with uring. Now, I need to know where I can find the code for `dev_uring.c`. My hunch is it's either going to be defined in `fs/fuse/Kconfig` which would allow me to know the kernel configuration options, or `fs/fuse/Makefile` will probably be my best bet to find the file or where the symbol is defined. I'll start there. Knowing this location will allow me to investigate the actual implementation details of how these tasks are integrated into the uring queue, like the data structures used, the scheduling mechanisms involved, and potential synchronization issues.

{
  "Expression": "dev_uring",
  "PathPrefix": "fs/fuse/"
}

{
  "Output": "fs/fuse/Makefile=19=fuse-$(CONFIG_SYSCTL) += sysctl.o\nfs/fuse/Makefile:20:fuse-$(CONFIG_FUSE_IO_URING) += dev_uring.o\nfs/fuse/Makefile-21-\n--\nfs/fuse/dev.c-8-#include \"args.h\"\nfs/fuse/dev.c:9:#include \"dev_uring_i.h\"\nfs/fuse/dev.c-10-\n--\nfs/fuse/dev_uring.c-8-#include \"args.h\"\nfs/fuse/dev_uring.c:9:#include \"dev_uring_i.h\"\nfs/fuse/dev_uring.c-10-#include \"fuse_trace.h\"\n--\nfs/fuse/req_timeout.c-5-#include \"fuse_dev_i.h\"\nfs/fuse/req_timeout.c:6:#include \"dev_uring_i.h\"\nfs/fuse/req_timeout.c-7-\n--\nfs/fuse/trace.c-5- */\nfs/fuse/trace.c:6:#include \"dev_uring_i.h\"\nfs/fuse/trace.c-7-#include \"fuse_i.h\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 3857
							output: 30
							thoughts: 34
						

Okay, here's my take on those thoughts, tailored for an expert audience, presented in the first person:

**Kernel Configuration Dependencies**

Alright, so the task at hand hinges on the `CONFIG_FUSE_IO_URING` kernel configuration option. My immediate reflex is to verify its presence and any associated dependencies. Given that it's related to FUSE and io_uring, I'll need to confirm its availability. My starting point will be `fs/fuse/Kconfig`. That's where all the FUSE-specific configurations are generally housed, so it's the logical place to look for details on `FUSE_IO_URING`. From there, I'll quickly check its symbol and any associated dependencies or default states to determine if any of these are the cause, as well as confirm if it's already enabled in the current configuration or needs to be enabled. I need to be sure before I move forward.

{
  "Expression": "FUSE_IO_URING",
  "PathPrefix": "fs/fuse/"
}

{
  "Output": "fs/fuse/Kconfig=57=config FUSE_PASSTHROUGH\n--\nfs/fuse/Kconfig-67-\nfs/fuse/Kconfig:68:config FUSE_IO_URING\nfs/fuse/Kconfig-69-\tbool \"FUSE communication over io-uring\"\n--\nfs/fuse/Makefile=19=fuse-$(CONFIG_SYSCTL) += sysctl.o\nfs/fuse/Makefile:20:fuse-$(CONFIG_FUSE_IO_URING) += dev_uring.o\nfs/fuse/Makefile-21-\n--\nfs/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=2378=const struct file_operations fuse_dev_operations = {\n--\nfs/fuse/dev.c-2389-\t.compat_ioctl   = compat_ptr_ioctl,\nfs/fuse/dev.c:2390:#ifdef CONFIG_FUSE_IO_URING\nfs/fuse/dev.c-2391-\t.uring_cmd\t= fuse_uring_cmd,\n--\nfs/fuse/dev.h=94=void fuse_copy_finish(struct fuse_copy_state *cs);\nfs/fuse/dev.h-95-\nfs/fuse/dev.h:96:#ifdef CONFIG_FUSE_IO_URING\nfs/fuse/dev.h-97-bool fuse_uring_enabled(void);\nfs/fuse/dev.h=98=void fuse_uring_destruct(struct fuse_chan *fch);\nfs/fuse/dev.h:99:#else /* CONFIG_FUSE_IO_URING */\nfs/fuse/dev.h-100-static inline bool fuse_uring_enabled(void)\n--\nfs/fuse/dev.h=105=static inline void fuse_uring_destruct(struct fuse_chan *fch)\n--\nfs/fuse/dev.h-107-}\nfs/fuse/dev.h:108:#endif /* CONFIG_FUSE_IO_URING */\nfs/fuse/dev.h-109-\n--\nfs/fuse/dev_uring.c=1218=int fuse_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags)\n--\nfs/fuse/dev_uring.c-1259-\tswitch (cmd_op) {\nfs/fuse/dev_uring.c:1260:\tcase FUSE_IO_URING_CMD_REGISTER:\nfs/fuse/dev_uring.c-1261-\t\terr = fuse_uring_register(cmd, issue_flags, fch);\nfs/fuse/dev_uring.c-1262-\t\tif (err) {\nfs/fuse/dev_uring.c:1263:\t\t\tpr_info_once(\"FUSE_IO_URING_CMD_REGISTER failed err=%d\\n\",\nfs/fuse/dev_uring.c-1264-\t\t\t\t     err);\n--\nfs/fuse/dev_uring.c-1269-\t\tbreak;\nfs/fuse/dev_uring.c:1270:\tcase FUSE_IO_URING_CMD_COMMIT_AND_FETCH:\nfs/fuse/dev_uring.c-1271-\t\terr = fuse_uring_commit_fetch(cmd, issue_flags, fch);\nfs/fuse/dev_uring.c-1272-\t\tif (err) {\nfs/fuse/dev_uring.c:1273:\t\t\tpr_info_once(\"FUSE_IO_URING_COMMIT_AND_FETCH failed err=%d\\n\",\nfs/fuse/dev_uring.c-1274-\t\t\t\t     err);\n--\nfs/fuse/dev_uring_i.h-11-\nfs/fuse/dev_uring_i.h:12:#ifdef CONFIG_FUSE_IO_URING\nfs/fuse/dev_uring_i.h-13-\n--\nfs/fuse/dev_uring_i.h=168=static inline bool fuse_uring_ready(struct fuse_chan *fch)\n--\nfs/fuse/dev_uring_i.h-174-\nfs/fuse/dev_uring_i.h:175:#else /* CONFIG_FUSE_IO_URING */\nfs/fuse/dev_uring_i.h-176-\n--\nfs/fuse/dev_uring_i.h=195=static inline bool fuse_uring_request_expired(struct fuse_chan *fch)\n--\nfs/fuse/dev_uring_i.h-199-\nfs/fuse/dev_uring_i.h:200:#endif /* CONFIG_FUSE_IO_URING */\nfs/fuse/dev_uring_i.h-201-\n--\nfs/fuse/fuse_dev_i.h=65=struct fuse_req {\n--\nfs/fuse/fuse_dev_i.h-109-\nfs/fuse/fuse_dev_i.h:110:#ifdef CONFIG_FUSE_IO_URING\nfs/fuse/fuse_dev_i.h-111-\tvoid *ring_entry;\n--\nfs/fuse/fuse_dev_i.h=190=struct fuse_chan {\n--\nfs/fuse/fuse_dev_i.h-262-\nfs/fuse/fuse_dev_i.h:263:#ifdef CONFIG_FUSE_IO_URING\nfs/fuse/fuse_dev_i.h-264-\t/**  uring connection information*/\n"
}

gemini-3.1-pro-preview

null

null

							input: 5650
							output: 33
							thoughts: 83
						

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

**Analyzing the FUSE_IO_URING Configuration and Patch**

Right, so we're talking about the `FUSE_IO_URING` configuration option here. My initial focus is on the impact of this specific patch. It appears to be zeroing in on `fuse_uring_task_to_queue`, that's the function that links tasks to the I/O queue. That's a critical area, as any change there is pretty fundamental.

Now, my mind's immediately going to trace where `fuse_uring_task_to_queue` is used. The notes clearly state it's employed within both `fuse_uring_queue_fuse_req` and `fuse_uring_queue_bq_req`. Okay, makes sense. These are the functions responsible for queuing different types of requests. Time to dig into those functions. I'll need to understand exactly how this modification to `fuse_uring_task_to_queue` is changing the queueing behavior for both standard FUSE requests and block-layer requests. This will be key to understanding the overall implications of the patch. I'll need to analyze the data structures, the locking, and the potential performance ramifications.

{
  "Expression": "fuse_uring_queue_fuse_req",
  "PathPrefix": "fs/fuse/"
}

{
  "Output": "fs/fuse/dev_uring.c=1384=static void fuse_uring_dispatch_ent(struct fuse_ring_ent *ent)\n--\nfs/fuse/dev_uring.c-1392-/* queue a fuse request and send it if a ring entry is available */\nfs/fuse/dev_uring.c:1393:void fuse_uring_queue_fuse_req(struct fuse_iqueue *fiq, struct fuse_req *req)\nfs/fuse/dev_uring.c-1394-{\n--\nfs/fuse/dev_uring.c=1491=static const struct fuse_iqueue_ops fuse_io_uring_ops = {\n--\nfs/fuse/dev_uring.c-1499-\t.send_interrupt = fuse_dev_queue_interrupt,\nfs/fuse/dev_uring.c:1500:\t.send_req = fuse_uring_queue_fuse_req,\nfs/fuse/dev_uring.c-1501-};\n--\nfs/fuse/dev_uring_i.h=140=int fuse_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags);\nfs/fuse/dev_uring_i.h:141:void fuse_uring_queue_fuse_req(struct fuse_iqueue *fiq, struct fuse_req *req);\nfs/fuse/dev_uring_i.h-142-bool fuse_uring_queue_bq_req(struct fuse_req *req);\n"
}

gemini-3.1-pro-preview

null

null

							input: 6413
							output: 31
							thoughts: 188
						

**Analyzing the FUSE io_uring Implementation**

Okay, so I'm looking at this `fuse_uring_queue_fuse_req` function and how it relates to `fuse_io_uring_ops.send_req`. The connection seems clear; it should be directly reachable and operating as expected. The patch adds something about finding an available queue when the current one is full. I need to focus on these functions: `fuse_uring_task_to_queue`, `fuse_uring_queue_fuse_req`, `fuse_uring_queue_bq_req`, and `fuse_uring_find_avail_queue`. These seem central to the new logic.

Let me quickly make sure there aren't any other related configurations. Right, `FUSE_IO_URING` is the key config here. Now, where is that defined? Ah, it's in `fs/fuse/Kconfig`. Excellent. Is there anything that depends on `FUSE_IO_URING`? I should probably check that same `fs/fuse/Kconfig` file for any dependencies.

{
  "Expression": "config FUSE_IO_URING",
  "PathPrefix": "fs/fuse/"
}

{
  "Output": "fs/fuse/Kconfig=57=config FUSE_PASSTHROUGH\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: 6948
							output: 33
							thoughts: 18
						

Here's my attempt at summarizing the thought process, tailored for an expert audience:

**Diving into FUSE Configuration**

Alright, let's zero in on the `fs/fuse/Kconfig` file, specifically around line 68. I'm probably looking for a specific configuration option related to FUSE. Given my experience, I'm expecting to find something fundamental, maybe related to device support, specific features, or default behavior. Knowing the Kconfig syntax, the structure around this line will likely involve a `config` block defining a boolean or tristate symbol. I’m anticipating a description, the `help` text, and potential dependencies or default values. My brain's already pre-loading the relevant kernel build system knowledge to interpret the context. Depending on what's there, my next steps could range from analyzing the dependencies to understand the broader implications of enabling or disabling this option, to checking the code that consumes this Kconfig symbol, or determining the implications for existing FUSE configurations. The line number is my initial entry point, I’m ready to quickly branch out and explore adjacent lines if necessary to understand the option's place in the larger FUSE configuration landscape.

{
  "File": "fs/fuse/Kconfig",
  "FirstLine": 50,
  "LineCount": 30
}

{
  "Contents": "  50:\t\thelp\n  51:\t\t  This allows bypassing guest page cache and allows mapping host page\n  52:\t\t  cache directly in guest address space.\n  53:\t\n  54:\t\t  If you want to allow mounting a Virtio Filesystem with the \"dax\"\n  55:\t\t  option, answer Y.\n  56:\t\n  57:\tconfig FUSE_PASSTHROUGH\n  58:\t\tbool \"FUSE passthrough operations support\"\n  59:\t\tdefault y\n  60:\t\tdepends on FUSE_FS\n  61:\t\tselect FS_STACK\n  62:\t\thelp\n  63:\t\t  This allows bypassing FUSE server by mapping specific FUSE operations\n  64:\t\t  to be performed directly on a backing file.\n  65:\t\n  66:\t\t  If you want to allow passthrough operations, answer Y.\n  67:\t\n  68:\tconfig FUSE_IO_URING\n  69:\t\tbool \"FUSE communication over io-uring\"\n  70:\t\tdefault y\n  71:\t\tdepends on FUSE_FS\n  72:\t\tdepends on IO_URING\n  73:\t\thelp\n  74:\t\t  This allows sending FUSE requests over the io-uring interface and\n  75:\t          also adds request core affinity.\n  76:\t\n  77:\t\t  If you want to allow fuse server/client communication through io-uring,\n  78:\t\t  answer Y\n"
}

gemini-3.1-pro-preview

null

null

							input: 7617
							output: 137
							thoughts: 990
						

**Analyzing the FUSE IO_URING Patch for Syzkaller Coverage**

Okay, so I'm looking at this `FUSE_IO_URING` configuration and trying to figure out the most effective way to leverage Syzkaller here. My initial thought is to identify key functions that this patch introduces or modifies, functions that are likely to be interesting from a fuzzing perspective.

I'm zeroing in on a few functions. `fuse_uring_task_to_queue`, `fuse_uring_queue_fuse_req`, and `fuse_uring_queue_bq_req` seem like solid candidates, but let me double-check about `fuse_uring_find_avail_queue`. It's `static`, which might make it trickier for Syzkaller, though it *is* present in the debug info. A quick check confirms `fuse_uring_find_avail_queue` is indeed defined in `fs/fuse/dev_uring.c`, as is `fuse_uring_task_to_queue`, so I'll include it in the list of symbols to focus on. Syzkaller *can* target static functions if the debug info is there, which is helpful.

Given the architecture of the patch, it seems `fuse_uring_queue_fuse_req` and `fuse_uring_queue_bq_req` are good entry points, and `fuse_uring_task_to_queue` is a critical routing function. I'll provide those to syzkaller, and also include `fuse_uring_find_avail_queue`.

Now, regarding configurations, it seems `FUSE_FS` and `IO_URING` are already enabled by default. So, `FUSE_IO_URING` is the only config I need to explicitly enable.

Let's review the patch again to make sure I'm capturing everything. The added code includes a function `fuse_uring_queue_has_avail_ent`. The new code modifies `fuse_uring_task_to_queue` such that it will search for another available queue if the initially selected queue has no available entries. This looks functional and reachable.

Based on this analysis, I'll set the results.

{
  "EnableConfigs": [
    "FUSE_IO_URING"
  ],
  "FocusSymbols": [
    "fuse_uring_task_to_queue",
    "fuse_uring_queue_fuse_req",
    "fuse_uring_queue_bq_req",
    "fuse_uring_find_avail_queue"
  ],
  "Reasoning": "The patch modifies the FUSE io-uring communication logic to find an available queue when the current task's queue has no available entries. This is a functional change in the FUSE subsystem that can be reached by using FUSE over io-uring.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "FUSE_IO_URING"
  ],
  "FocusSymbols": [
    "fuse_uring_task_to_queue",
    "fuse_uring_queue_fuse_req",
    "fuse_uring_queue_bq_req",
    "fuse_uring_find_avail_queue"
  ],
  "Reasoning": "The patch modifies the FUSE io-uring communication logic to find an available queue when the current task's queue has no available entries. This is a functional change in the FUSE subsystem that can be reached by using FUSE over io-uring.",
  "WorthFuzzing": true
}