AI Trajectory

null

{
  "EnableConfigs": [
    "FUSE_FS"
  ],
  "FocusSymbols": [
    "fuse_send_write_pages",
    "fuse_fill_write_pages",
    "fuse_notify_store",
    "iomap_folio_mark_uptodate",
    "iomap_folio_clear_uptodate"
  ],
  "Reasoning": "The patch introduces new iomap folio uptodate management functions (`iomap_folio_mark_uptodate`, `iomap_folio_clear_uptodate`) and integrates them into the FUSE filesystem's write and notify paths. This is a functional change in core filesystem and FUSE logic that handles folio state, which could lead to data corruption or crashes if incorrect.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit cf99b81d6f4ed6eae9c0c96408e085c42cc4e520\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Tue Jun 23 20:41:53 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/fs/fuse/file.c b/fs/fuse/file.c\nindex e052a0d44dee06..12a2aa605f6b31 100644\n--- a/fs/fuse/file.c\n+++ b/fs/fuse/file.c\n@@ -1250,13 +1250,13 @@ static ssize_t fuse_send_write_pages(struct fuse_io_args *ia,\n \t\tstruct folio *folio = ap-\u003efolios[i];\n \n \t\tif (err) {\n-\t\t\tfolio_clear_uptodate(folio);\n+\t\t\tiomap_folio_clear_uptodate(folio);\n \t\t} else {\n \t\t\tif (count \u003e= folio_size(folio) - offset)\n \t\t\t\tcount -= folio_size(folio) - offset;\n \t\t\telse {\n \t\t\t\tif (short_write)\n-\t\t\t\t\tfolio_clear_uptodate(folio);\n+\t\t\t\t\tiomap_folio_clear_uptodate(folio);\n \t\t\t\tcount = 0;\n \t\t\t}\n \t\t\toffset = 0;\n@@ -1335,7 +1335,7 @@ static ssize_t fuse_fill_write_pages(struct fuse_io_args *ia,\n \n \t\t/* If we copied full folio, mark it uptodate */\n \t\tif (tmp == folio_size(folio))\n-\t\t\tfolio_mark_uptodate(folio);\n+\t\t\tiomap_folio_mark_uptodate(folio);\n \n \t\tif (folio_test_uptodate(folio)) {\n \t\t\tfolio_unlock(folio);\ndiff --git a/fs/fuse/notify.c b/fs/fuse/notify.c\nindex 29578104ae6cd6..1ba763705d9119 100644\n--- a/fs/fuse/notify.c\n+++ b/fs/fuse/notify.c\n@@ -2,6 +2,8 @@\n \n #include \"dev.h\"\n #include \"fuse_i.h\"\n+\n+#include \u003clinux/iomap.h\u003e\n #include \u003clinux/pagemap.h\u003e\n \n static int fuse_notify_poll(struct fuse_conn *fc, unsigned int size,\n@@ -192,7 +194,7 @@ static int fuse_notify_store(struct fuse_conn *fc, unsigned int size,\n \t\tif (!folio_test_uptodate(folio) \u0026\u0026 !err \u0026\u0026 folio_offset == 0 \u0026\u0026\n \t\t    (nr_bytes == folio_size(folio) || file_size == end)) {\n \t\t\tfolio_zero_segment(folio, nr_bytes, folio_size(folio));\n-\t\t\tfolio_mark_uptodate(folio);\n+\t\t\tiomap_folio_mark_uptodate(folio);\n \t\t}\n \t\tfolio_unlock(folio);\n \t\tfolio_put(folio);\ndiff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c\nindex 8d4806dc46d468..317fa7af98bd23 100644\n--- a/fs/iomap/buffered-io.c\n+++ b/fs/iomap/buffered-io.c\n@@ -105,6 +105,33 @@ static void iomap_set_range_uptodate(struct folio *folio, size_t off,\n \t\tfolio_mark_uptodate(folio);\n }\n \n+void iomap_folio_mark_uptodate(struct folio *folio)\n+{\n+\tiomap_set_range_uptodate(folio, 0, folio_size(folio));\n+}\n+EXPORT_SYMBOL_GPL(iomap_folio_mark_uptodate);\n+\n+void iomap_folio_clear_uptodate(struct folio *folio)\n+{\n+\tstruct iomap_folio_state *ifs = folio-\u003eprivate;\n+\tunsigned long flags;\n+\n+\tif (!folio_test_uptodate(folio))\n+\t\treturn;\n+\n+\tif (ifs) {\n+\t\tstruct inode *inode = folio-\u003emapping-\u003ehost;\n+\t\tunsigned int nr_blks = i_blocks_per_folio(inode, folio);\n+\n+\t\tspin_lock_irqsave(\u0026ifs-\u003estate_lock, flags);\n+\t\tbitmap_clear(ifs-\u003estate, 0, nr_blks);\n+\t\tspin_unlock_irqrestore(\u0026ifs-\u003estate_lock, flags);\n+\t}\n+\n+\tfolio_clear_uptodate(folio);\n+}\n+EXPORT_SYMBOL_GPL(iomap_folio_clear_uptodate);\n+\n /*\n  * Find the next dirty block in the folio. end_blk is inclusive.\n  * If no dirty block is found, this will return end_blk + 1.\ndiff --git a/include/linux/iomap.h b/include/linux/iomap.h\nindex 3582ed1fe23611..f13ae425f5529b 100644\n--- a/include/linux/iomap.h\n+++ b/include/linux/iomap.h\n@@ -365,6 +365,8 @@ struct folio *iomap_get_folio(struct iomap_iter *iter, loff_t pos, size_t len);\n bool iomap_release_folio(struct folio *folio, gfp_t gfp_flags);\n void iomap_invalidate_folio(struct folio *folio, size_t offset, size_t len);\n bool iomap_dirty_folio(struct address_space *mapping, struct folio *folio);\n+void iomap_folio_mark_uptodate(struct folio *folio);\n+void iomap_folio_clear_uptodate(struct folio *folio);\n int iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,\n \t\tconst struct iomap_ops *ops,\n \t\tconst struct iomap_write_ops *write_ops);\n"
}

gemini-3.1-pro-preview

null

{
  "EnableConfigs": [
    "FUSE_FS"
  ],
  "FocusSymbols": [
    "fuse_send_write_pages",
    "fuse_fill_write_pages",
    "fuse_notify_store",
    "iomap_folio_mark_uptodate",
    "iomap_folio_clear_uptodate"
  ],
  "Reasoning": "The patch introduces new iomap folio uptodate management functions (`iomap_folio_mark_uptodate`, `iomap_folio_clear_uptodate`) and integrates them into the FUSE filesystem's write and notify paths. This is a functional change in core filesystem and FUSE logic that handles folio state, which could lead to data corruption or crashes if incorrect.",
  "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 cf99b81d6f4ed6eae9c0c96408e085c42cc4e520
Author: syz-cluster <triage@syzkaller.com>
Date:   Tue Jun 23 20:41:53 2026 +0000

    syz-cluster: applied patch under review

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index e052a0d44dee06..12a2aa605f6b31 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1250,13 +1250,13 @@ static ssize_t fuse_send_write_pages(struct fuse_io_args *ia,
 		struct folio *folio = ap->folios[i];
 
 		if (err) {
-			folio_clear_uptodate(folio);
+			iomap_folio_clear_uptodate(folio);
 		} else {
 			if (count >= folio_size(folio) - offset)
 				count -= folio_size(folio) - offset;
 			else {
 				if (short_write)
-					folio_clear_uptodate(folio);
+					iomap_folio_clear_uptodate(folio);
 				count = 0;
 			}
 			offset = 0;
@@ -1335,7 +1335,7 @@ static ssize_t fuse_fill_write_pages(struct fuse_io_args *ia,
 
 		/* If we copied full folio, mark it uptodate */
 		if (tmp == folio_size(folio))
-			folio_mark_uptodate(folio);
+			iomap_folio_mark_uptodate(folio);
 
 		if (folio_test_uptodate(folio)) {
 			folio_unlock(folio);
diff --git a/fs/fuse/notify.c b/fs/fuse/notify.c
index 29578104ae6cd6..1ba763705d9119 100644
--- a/fs/fuse/notify.c
+++ b/fs/fuse/notify.c
@@ -2,6 +2,8 @@
 
 #include "dev.h"
 #include "fuse_i.h"
+
+#include <linux/iomap.h>
 #include <linux/pagemap.h>
 
 static int fuse_notify_poll(struct fuse_conn *fc, unsigned int size,
@@ -192,7 +194,7 @@ static int fuse_notify_store(struct fuse_conn *fc, unsigned int size,
 		if (!folio_test_uptodate(folio) && !err && folio_offset == 0 &&
 		    (nr_bytes == folio_size(folio) || file_size == end)) {
 			folio_zero_segment(folio, nr_bytes, folio_size(folio));
-			folio_mark_uptodate(folio);
+			iomap_folio_mark_uptodate(folio);
 		}
 		folio_unlock(folio);
 		folio_put(folio);
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 8d4806dc46d468..317fa7af98bd23 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -105,6 +105,33 @@ static void iomap_set_range_uptodate(struct folio *folio, size_t off,
 		folio_mark_uptodate(folio);
 }
 
+void iomap_folio_mark_uptodate(struct folio *folio)
+{
+	iomap_set_range_uptodate(folio, 0, folio_size(folio));
+}
+EXPORT_SYMBOL_GPL(iomap_folio_mark_uptodate);
+
+void iomap_folio_clear_uptodate(struct folio *folio)
+{
+	struct iomap_folio_state *ifs = folio->private;
+	unsigned long flags;
+
+	if (!folio_test_uptodate(folio))
+		return;
+
+	if (ifs) {
+		struct inode *inode = folio->mapping->host;
+		unsigned int nr_blks = i_blocks_per_folio(inode, folio);
+
+		spin_lock_irqsave(&ifs->state_lock, flags);
+		bitmap_clear(ifs->state, 0, nr_blks);
+		spin_unlock_irqrestore(&ifs->state_lock, flags);
+	}
+
+	folio_clear_uptodate(folio);
+}
+EXPORT_SYMBOL_GPL(iomap_folio_clear_uptodate);
+
 /*
  * Find the next dirty block in the folio. end_blk is inclusive.
  * If no dirty block is found, this will return end_blk + 1.
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 3582ed1fe23611..f13ae425f5529b 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -365,6 +365,8 @@ struct folio *iomap_get_folio(struct iomap_iter *iter, loff_t pos, size_t len);
 bool iomap_release_folio(struct folio *folio, gfp_t gfp_flags);
 void iomap_invalidate_folio(struct folio *folio, size_t offset, size_t len);
 bool iomap_dirty_folio(struct address_space *mapping, struct folio *folio);
+void iomap_folio_mark_uptodate(struct folio *folio);
+void iomap_folio_clear_uptodate(struct folio *folio);
 int iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,
 		const struct iomap_ops *ops,
 		const struct iomap_write_ops *write_ops);

gemini-3.1-pro-preview

null

null

							input: 3122
							output: 31
							thoughts: 226
						

**FUSE/IOMAP Folio Uptodate State Update Fuzzing Plan**

Okay, so we have a patch that's introducing changes related to how FUSE interacts with the folio uptodate state, specifically using `iomap_folio_mark_uptodate` and `iomap_folio_clear_uptodate`. These new functions are in `fs/iomap/buffered-io.c` and being used by `fs/fuse/file.c` and `fs/fuse/notify.c`, so we're talking about a functional change that requires careful fuzzing. This is a good opportunity to uncover potential issues in how FUSE and IOMAP interact, especially around these new state management routines.

My initial focus will be on the critical functions directly impacted: `fuse_send_write_pages`, `fuse_fill_write_pages`, and `fuse_notify_store`. These are the FUSE-specific entry points. But of course, the new IOMAP functions themselves are crucial: `iomap_folio_mark_uptodate` and `iomap_folio_clear_uptodate` which this patch introduces. I need to make sure my fuzzing targets all of these.

Next, I need to make sure the kernel is configured correctly for this work. We have `CONFIG_FUSE_FS` enabling FUSE, and `CONFIG_FS_IOMAP` enabling IOMAP. I'll verify that these options are indeed enabled during my fuzzing runs. It is important to know if these are enabled, especially if the fuzzing generates builds.

{
  "Expression": "config FUSE_FS",
  "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"
}

gemini-3.1-pro-preview

null

null

							input: 3802
							output: 34
							thoughts: 7
						

Okay, here's my attempt at summarizing the thought process, tailored for an expert audience, and delivered as a first-person perspective:

**My Deep Dive into FS_IOMAP**

Alright, let's unpack this FS_IOMAP stuff. My initial impression is that this is a critical piece, a foundational element in modern file system design, particularly when dealing with the challenges of direct I/O and concurrent access. I immediately see the importance of understanding how this structure, or the set of structures, facilitates the mapping between logical file offsets and the physical blocks on disk. It’s the linchpin, isn't it? Without a robust IOMAP, efficiently navigating and managing the complexities of data placement and retrieval would be a nightmare, especially considering the need for operations like sparse files, hole punching, and block allocation.

I'm thinking about the various implementations I've encountered and the trade-offs they represent. The choice of the IOMAP structure has profound implications on performance. Consider the impact on metadata operations, the overhead of lookups, and the potential for contention. Different strategies are going to shine under different workloads. We're talking about sophisticated algorithms that need to handle complex scenarios like extending and truncating files, handling fragmented data, and dealing with concurrent access from multiple processes. Understanding the intricacies of caching mechanisms here is also critical; it’s an optimization game.

I also see its relevance in modern file systems that support advanced features like copy-on-write, snapshots, or even data deduplication. How does the IOMAP interact with these functionalities? Does it need to be modified or extended to support them effectively? The way it handles these things are going to be key to efficiency.

I’m particularly interested in the IOMAP's interaction with the block allocator. How does it ensure that data is placed in the most efficient manner, considering factors like disk layout, RAID configurations, and SSD wear leveling? Are there techniques to minimize fragmentation or optimize for sequential access patterns? And what about the impact on error handling and data integrity? When a block goes bad, how does the IOMAP help to recover and ensure the file system remains consistent? I imagine robust journaling or transaction logging is a must to keep the system in a consistent state.

Ultimately, I view this as a sophisticated, finely-tuned instrument. Its design directly impacts overall file system performance, scalability, and reliability. Mastering it is key to designing high-performance and robust storage solutions. It’s an area where deep understanding is always worth the effort.

no matches

{
  "Expression": "config FS_IOMAP",
  "PathPrefix": "fs/iomap/Kconfig"
}

{
  "error": "no matches"
}

gemini-3.1-pro-preview

null

null

							input: 4385
							output: 30
							thoughts: 15
						

Okay, here's my take on those thoughts, tailored for an expert audience:

**Investigating the FS_IOMAP Configuration Option**

Alright, let's dive in. My immediate thought is to go straight to the source – the `fs/Kconfig` file. I need to understand the current state of `FS_IOMAP`. I want to know where it's defined, what dependencies it might have, what the default setting is, and what the associated help text says. Understanding the configuration options is paramount. I need to be sure about its implications and what other features are tied to this one. This Kconfig file will be the starting point to understand the wider system's configuration.

{
  "Expression": "config FS_IOMAP",
  "PathPrefix": "fs/Kconfig"
}

{
  "Output": "fs/Kconfig=12=config VALIDATE_FS_PARSER\n--\nfs/Kconfig-17-\nfs/Kconfig:18:config FS_IOMAP\nfs/Kconfig-19-\tbool\n"
}

gemini-3.1-pro-preview

null

null

							input: 4644
							output: 32
							thoughts: 35
						

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

**Investigating FS_IOMAP and FUSE Compatibility**

Alright, let's dive in. I know `FS_IOMAP` is a boolean config, and I'm pretty familiar with how it's typically used and selected by other filesystems. But I'm curious about the specific interaction with FUSE. So, I need to check something – is `FS_IOMAP` actually enabled by default within FUSE itself? Or is it simply available as an option that FUSE *could* leverage if configured elsewhere? I need to understand whether FUSE proactively utilizes it, or if it's passive, essentially just providing the hooks if the underlying storage layer or a higher-level module chooses to use it. That's the key question I need to answer right now. Knowing the relationship here will help me understand how FUSE interacts with I/O and potential optimization strategies.

{
  "Expression": "select FS_IOMAP",
  "PathPrefix": "fs/fuse/Kconfig"
}

{
  "Output": "fs/fuse/Kconfig=2=config FUSE_FS\n--\nfs/fuse/Kconfig-4-\tselect FS_POSIX_ACL\nfs/fuse/Kconfig:5:\tselect FS_IOMAP\nfs/fuse/Kconfig-6-\thelp\n"
}

gemini-3.1-pro-preview

null

null

							input: 4997
							output: 174
							thoughts: 482
						

**Analyzing the FUSE Filesystem Change for Potential Issues**

Okay, so FUSE_FS is the key config here, as it selects FS_IOMAP, meaning we are specifically dealing with FUSE's interaction with the I/O mapping system. My focus needs to be on these functions: `fuse_send_write_pages`, `fuse_fill_write_pages`, `fuse_notify_store`, `iomap_folio_mark_uptodate`, and `iomap_folio_clear_uptodate`.

First, let's establish context. `fuse_send_write_pages` is definitely part of the FUSE write path, so it's likely a hot path, though specific to FUSE writes. `fuse_notify_store` is also FUSE-specific. The `iomap_folio_mark_uptodate` and `iomap_folio_clear_uptodate` functions are *new*, and therefore inherently interesting from a fuzzing perspective, especially given the potential for off-by-one errors or incorrect state management.

The reasoning is pretty straightforward: this patch integrates new folio uptodate management functions (`iomap_folio_mark_uptodate`, `iomap_folio_clear_uptodate`) within the FUSE write and notify paths, which involve core filesystem logic and FUSE. Incorrect handling of folio state is a classic source of data corruption or crashes, so I need to see this clearly.

Given that `fuse_fill_write_pages` and `fuse_send_write_pages` are part of the FUSE write path, this patch is introducing a change in precisely the logic where it's most important to test. `fuse_notify_store` is also specific to FUSE and a good target, but since the new functions are new, they are high priority for a quick fuzz to see if they're handled correctly.

I'm thinking I'll use `set-results` here to get this done.

{
  "EnableConfigs": [
    "FUSE_FS"
  ],
  "FocusSymbols": [
    "fuse_send_write_pages",
    "fuse_fill_write_pages",
    "fuse_notify_store",
    "iomap_folio_mark_uptodate",
    "iomap_folio_clear_uptodate"
  ],
  "Reasoning": "The patch introduces new iomap folio uptodate management functions (`iomap_folio_mark_uptodate`, `iomap_folio_clear_uptodate`) and integrates them into the FUSE filesystem's write and notify paths. This is a functional change in core filesystem and FUSE logic that handles folio state, which could lead to data corruption or crashes if incorrect.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "FUSE_FS"
  ],
  "FocusSymbols": [
    "fuse_send_write_pages",
    "fuse_fill_write_pages",
    "fuse_notify_store",
    "iomap_folio_mark_uptodate",
    "iomap_folio_clear_uptodate"
  ],
  "Reasoning": "The patch introduces new iomap folio uptodate management functions (`iomap_folio_mark_uptodate`, `iomap_folio_clear_uptodate`) and integrates them into the FUSE filesystem's write and notify paths. This is a functional change in core filesystem and FUSE logic that handles folio state, which could lead to data corruption or crashes if incorrect.",
  "WorthFuzzing": true
}