AI Trajectory

null

{
  "EnableConfigs": [
    "NETFS_SUPPORT",
    "FSCACHE",
    "CACHEFILES",
    "AFS_FS"
  ],
  "FocusSymbols": [
    "netfs_wb_begin",
    "netfs_wb_end",
    "netfs_unbuffered_write_iter",
    "netfs_unbuffered_write_iter_locked",
    "netfs_writepages",
    "netfs_writeback_single",
    "netfs_write_begin",
    "netfs_perform_write",
    "iov_iter_extract_pages",
    "extract_iter_to_sg"
  ],
  "Reasoning": "The patch modifies core netfs logic, including writeback locking, unbuffered writes, and iterator extraction functions. It also affects cachefiles and AFS. These changes are functional and reachable, so they should be fuzzed.",
  "WorthFuzzing": true
}

null

{
  "PatchDiff": "commit 904b94d40e085ea0bc0fb2be616a561964048287\nAuthor: syz-cluster \u003ctriage@syzkaller.com\u003e\nDate:   Thu Jun 25 14:22:58 2026 +0000\n\n    syz-cluster: applied patch under review\n\ndiff --git a/fs/afs/symlink.c b/fs/afs/symlink.c\nindex ed5868369f372d..16b4823cb7b7e7 100644\n--- a/fs/afs/symlink.c\n+++ b/fs/afs/symlink.c\n@@ -255,11 +255,11 @@ int afs_symlink_writepages(struct address_space *mapping,\n \t}\n \n \tif (ret == 0) {\n-\t\tmutex_lock(\u0026vnode-\u003enetfs.wb_lock);\n+\t\tnetfs_wb_begin(\u0026vnode-\u003enetfs, false);\n \t\tnetfs_free_folioq_buffer(vnode-\u003edirectory);\n \t\tvnode-\u003edirectory = NULL;\n \t\tvnode-\u003edirectory_size = 0;\n-\t\tmutex_unlock(\u0026vnode-\u003enetfs.wb_lock);\n+\t\tnetfs_wb_end(\u0026vnode-\u003enetfs);\n \t} else if (ret == 1) {\n \t\tret = 0; /* Skipped write due to lock conflict. */\n \t}\ndiff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c\nindex 2937db690b40b5..d4309dfb55df4e 100644\n--- a/fs/cachefiles/namei.c\n+++ b/fs/cachefiles/namei.c\n@@ -375,7 +375,7 @@ int cachefiles_bury_object(struct cachefiles_cache *cache,\n \t\t\t\t\t    \"Rename failed with error %d\", ret);\n \t}\n \n-\t__cachefiles_unmark_inode_in_use(object, d_inode(rep));\n+\tcachefiles_do_unmark_inode_in_use(object, d_inode(rep));\n \tend_renaming(\u0026rd);\n \t_leave(\" = 0\");\n \treturn 0;\n@@ -467,7 +467,6 @@ struct file *cachefiles_create_tmpfile(struct cachefiles_object *object)\n \tret = -EINVAL;\n \tif (unlikely(!file-\u003ef_op-\u003eread_iter) ||\n \t    unlikely(!file-\u003ef_op-\u003ewrite_iter)) {\n-\t\tfput(file);\n \t\tpr_notice(\"Cache does not support read_iter and write_iter\\n\");\n \t\tgoto err_unuse;\n \t}\ndiff --git a/fs/netfs/buffered_read.c b/fs/netfs/buffered_read.c\nindex 76d0f6a29abab2..24a8a5418e3119 100644\n--- a/fs/netfs/buffered_read.c\n+++ b/fs/netfs/buffered_read.c\n@@ -659,7 +659,7 @@ int netfs_write_begin(struct netfs_inode *ctx,\n \t * within the cache granule containing the EOF, in which case we need\n \t * to preload the granule.\n \t */\n-\tif (!netfs_is_cache_enabled(ctx) \u0026\u0026\n+\tif (!netfs_is_cache_maybe_enabled(ctx) \u0026\u0026\n \t    netfs_skip_folio_read(folio, pos, len, false)) {\n \t\tnetfs_stat(\u0026netfs_n_rh_write_zskip);\n \t\tgoto have_folio_no_wait;\ndiff --git a/fs/netfs/buffered_write.c b/fs/netfs/buffered_write.c\nindex 6bde3320bcec66..2cdb68e6b16fff 100644\n--- a/fs/netfs/buffered_write.c\n+++ b/fs/netfs/buffered_write.c\n@@ -277,7 +277,7 @@ ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,\n \t\t * caching service temporarily because the backing store got\n \t\t * culled.\n \t\t */\n-\t\tif (netfs_is_cache_enabled(ctx)) {\n+\t\tif (netfs_is_cache_maybe_enabled(ctx)) {\n \t\t\tif (finfo) {\n \t\t\t\tnetfs_stat(\u0026netfs_n_wh_wstream_conflict);\n \t\t\t\tgoto flush_content;\ndiff --git a/fs/netfs/direct_write.c b/fs/netfs/direct_write.c\nindex 25f8ceb15fad64..c16fbad286a177 100644\n--- a/fs/netfs/direct_write.c\n+++ b/fs/netfs/direct_write.c\n@@ -166,13 +166,16 @@ static int netfs_unbuffered_write(struct netfs_io_request *wreq)\n \t\t */\n \t\tsubreq-\u003eerror = -EAGAIN;\n \t\ttrace_netfs_sreq(subreq, netfs_sreq_trace_retry);\n-\t\tif (subreq-\u003etransferred \u003e 0)\n+\t\tif (subreq-\u003etransferred \u003e 0) {\n \t\t\tiov_iter_advance(\u0026wreq-\u003ebuffer.iter, subreq-\u003etransferred);\n+\t\t\twreq-\u003etransferred += subreq-\u003etransferred;\n+\t\t}\n \n \t\tif (stream-\u003esource == NETFS_UPLOAD_TO_SERVER \u0026\u0026\n \t\t    wreq-\u003enetfs_ops-\u003eretry_request)\n \t\t\twreq-\u003enetfs_ops-\u003eretry_request(wreq, stream);\n \n+\t\t__clear_bit(NETFS_SREQ_MADE_PROGRESS, \u0026subreq-\u003eflags);\n \t\t__clear_bit(NETFS_SREQ_NEED_RETRY, \u0026subreq-\u003eflags);\n \t\t__clear_bit(NETFS_SREQ_BOUNDARY, \u0026subreq-\u003eflags);\n \t\t__clear_bit(NETFS_SREQ_FAILED, \u0026subreq-\u003eflags);\n@@ -186,17 +189,10 @@ static int netfs_unbuffered_write(struct netfs_io_request *wreq)\n \n \t\tnetfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit);\n \n-\t\tif (stream-\u003eprepare_write) {\n+\t\tif (stream-\u003eprepare_write)\n \t\t\tstream-\u003eprepare_write(subreq);\n-\t\t\t__set_bit(NETFS_SREQ_IN_PROGRESS, \u0026subreq-\u003eflags);\n-\t\t\tnetfs_stat(\u0026netfs_n_wh_retry_write_subreq);\n-\t\t} else {\n-\t\t\tstruct iov_iter source;\n-\n-\t\t\tnetfs_reset_iter(subreq);\n-\t\t\tsource = subreq-\u003eio_iter;\n-\t\t\tnetfs_reissue_write(stream, subreq, \u0026source);\n-\t\t}\n+\t\t__set_bit(NETFS_SREQ_IN_PROGRESS, \u0026subreq-\u003eflags);\n+\t\tnetfs_stat(\u0026netfs_n_wh_retry_write_subreq);\n \t}\n \n \tnetfs_unbuffered_write_done(wreq);\ndiff --git a/fs/netfs/internal.h b/fs/netfs/internal.h\nindex 645996ecfc8036..d889caa401dc24 100644\n--- a/fs/netfs/internal.h\n+++ b/fs/netfs/internal.h\n@@ -239,6 +239,18 @@ static inline bool netfs_is_cache_enabled(struct netfs_inode *ctx)\n #endif\n }\n \n+static inline bool netfs_is_cache_maybe_enabled(struct netfs_inode *ctx)\n+{\n+#if IS_ENABLED(CONFIG_FSCACHE)\n+\tstruct fscache_cookie *cookie = ctx-\u003ecache;\n+\n+\treturn fscache_cookie_valid(cookie) \u0026\u0026\n+\t\ttest_bit(FSCACHE_COOKIE_IS_CACHING, \u0026cookie-\u003eflags);\n+#else\n+\treturn false;\n+#endif\n+}\n+\n /*\n  * Get a ref on a netfs group attached to a dirty page (e.g. a ceph snap).\n  */\ndiff --git a/fs/netfs/locking.c b/fs/netfs/locking.c\nindex 2249ecd09d0a8d..4e3be2b8150408 100644\n--- a/fs/netfs/locking.c\n+++ b/fs/netfs/locking.c\n@@ -9,6 +9,11 @@\n #include \u003clinux/netfs.h\u003e\n #include \"internal.h\"\n \n+struct netfs_wb_waiter {\n+\tstruct list_head\tlink;\t\t/* Link in ictx-\u003ewb_queue */\n+\tstruct task_struct\t*waiter;\t/* Waiter task; cleared when lock granted */\n+};\n+\n /*\n  * inode_dio_wait_interruptible - wait for outstanding DIO requests to finish\n  * @inode: inode to wait for\n@@ -203,3 +208,93 @@ void netfs_end_io_direct(struct inode *inode)\n \tup_read(\u0026inode-\u003ei_rwsem);\n }\n EXPORT_SYMBOL(netfs_end_io_direct);\n+\n+/*\n+ * Wait to have exclusive access to writeback.\n+ */\n+static bool netfs_wb_begin_wait(struct netfs_inode *ictx)\n+{\n+\tstruct netfs_wb_waiter waiter = {};\n+\tstruct task_struct *tsk = current;\n+\tbool got = false;\n+\n+\tspin_lock(\u0026ictx-\u003elock);\n+\n+\tif (test_and_set_bit_lock(NETFS_ICTX_WB_LOCK, \u0026ictx-\u003eflags)) {\n+\t\tget_task_struct(tsk);\n+\t\twaiter.waiter = tsk;\n+\t\tlist_add_tail(\u0026waiter.link, \u0026ictx-\u003ewb_queue);\n+\t} else {\n+\t\tgot = true;\n+\t}\n+\tspin_unlock(\u0026ictx-\u003elock);\n+\n+\tif (!got) {\n+\t\tfor (;;) {\n+\t\t\tset_current_state(TASK_UNINTERRUPTIBLE);\n+\t\t\t/* Read waiter before accessing inode state. */\n+\t\t\tif (smp_load_acquire(\u0026waiter.waiter) == NULL)\n+\t\t\t\tbreak;\n+\t\t\tschedule();\n+\t\t}\n+\t}\n+\t__set_current_state(TASK_RUNNING);\n+\treturn true;\n+}\n+\n+/**\n+ * netfs_wb_begin - Begin writeback, waiting if need be\n+ * @ictx: The inode to get writeback access on\n+ * @nowait: Return failure immediately rather than waiting if true\n+ *\n+ * Begin writeback to an inode, waiting for exclusive access if @nowait is\n+ * false.  This prevents collection from being done out of order with respect\n+ * to the issuance of write subrequests.\n+ *\n+ * Note that writeback may be ended in a different process (e.g. the collection\n+ * function on a workqueue) than started it.\n+ *\n+ * Return: True if can proceed, false if denied.\n+ */\n+bool netfs_wb_begin(struct netfs_inode *ictx, bool nowait)\n+{\n+\tif (!test_and_set_bit_lock(NETFS_ICTX_WB_LOCK, \u0026ictx-\u003eflags))\n+\t\treturn true;\n+\tif (nowait) {\n+\t\tnetfs_stat(\u0026netfs_n_wb_lock_skip);\n+\t\treturn false;\n+\t}\n+\tnetfs_stat(\u0026netfs_n_wb_lock_wait);\n+\treturn netfs_wb_begin_wait(ictx);\n+}\n+EXPORT_SYMBOL(netfs_wb_begin);\n+\n+/* netfs_wb_end - End writeback\n+ * @ictx: The inode we have writeback access to\n+ *\n+ * End writeback access on an inode, waking up the next writeback request.\n+ */\n+void netfs_wb_end(struct netfs_inode *ictx)\n+{\n+\tstruct netfs_wb_waiter *waiter;\n+\tstruct task_struct *tsk;\n+\n+\tWARN_ON_ONCE(!test_bit(NETFS_ICTX_WB_LOCK, \u0026ictx-\u003eflags));\n+\n+\tspin_lock(\u0026ictx-\u003elock);\n+\n+\twaiter = list_first_entry_or_null(\u0026ictx-\u003ewb_queue, struct netfs_wb_waiter, link);\n+\tif (waiter) {\n+\t\tlist_del(\u0026waiter-\u003elink);\n+\t\ttsk = waiter-\u003ewaiter;\n+\t\t/* Write inode state before clearing waiter. */\n+\t\tsmp_store_release(\u0026waiter-\u003ewaiter, NULL);\n+\t\twake_up_process(tsk);\n+\t\tput_task_struct(tsk);\n+\t} else {\n+\t\tclear_bit_unlock(NETFS_ICTX_WB_LOCK, \u0026ictx-\u003eflags);\n+\t}\n+\n+\tspin_unlock(\u0026ictx-\u003elock);\n+}\n+EXPORT_SYMBOL(netfs_wb_end);\ndiff --git a/fs/netfs/write_collect.c b/fs/netfs/write_collect.c\nindex 24fc2bb2f8a47b..210eb8f3958d77 100644\n--- a/fs/netfs/write_collect.c\n+++ b/fs/netfs/write_collect.c\n@@ -408,6 +408,16 @@ bool netfs_write_collection(struct netfs_io_request *wreq)\n \tnetfs_wake_rreq_flag(wreq, NETFS_RREQ_IN_PROGRESS, netfs_rreq_trace_wake_ip);\n \t/* As we cleared NETFS_RREQ_IN_PROGRESS, we acquired its ref. */\n \n+\tswitch (wreq-\u003eorigin) {\n+\tcase NETFS_WRITEBACK:\n+\tcase NETFS_WRITEBACK_SINGLE:\n+\tcase NETFS_WRITETHROUGH:\n+\t\tnetfs_wb_end(ictx);\n+\t\tbreak;\n+\tdefault:\n+\t\tbreak;\n+\t}\n+\n \tif (wreq-\u003eiocb) {\n \t\tsize_t written = min(wreq-\u003etransferred, wreq-\u003elen);\n \t\twreq-\u003eiocb-\u003eki_pos += written;\ndiff --git a/fs/netfs/write_issue.c b/fs/netfs/write_issue.c\nindex c03c7cc45e4716..f2761c99795a6b 100644\n--- a/fs/netfs/write_issue.c\n+++ b/fs/netfs/write_issue.c\n@@ -106,7 +106,7 @@ struct netfs_io_request *netfs_create_write_req(struct address_space *mapping,\n \t_enter(\"R=%x\", wreq-\u003edebug_id);\n \n \tictx = netfs_inode(wreq-\u003einode);\n-\tif (is_cacheable \u0026\u0026 netfs_is_cache_enabled(ictx))\n+\tif (is_cacheable)\n \t\tfscache_begin_write_operation(\u0026wreq-\u003ecache_resources, netfs_i_cookie(ictx));\n \tif (rolling_buffer_init(\u0026wreq-\u003ebuffer, wreq-\u003edebug_id, ITER_SOURCE) \u003c 0)\n \t\tgoto nomem;\n@@ -551,14 +551,8 @@ int netfs_writepages(struct address_space *mapping,\n \tstruct folio *folio;\n \tint error = 0;\n \n-\tif (!mutex_trylock(\u0026ictx-\u003ewb_lock)) {\n-\t\tif (wbc-\u003esync_mode == WB_SYNC_NONE) {\n-\t\t\tnetfs_stat(\u0026netfs_n_wb_lock_skip);\n-\t\t\treturn 0;\n-\t\t}\n-\t\tnetfs_stat(\u0026netfs_n_wb_lock_wait);\n-\t\tmutex_lock(\u0026ictx-\u003ewb_lock);\n-\t}\n+\tif (!netfs_wb_begin(ictx, wbc-\u003esync_mode == WB_SYNC_NONE))\n+\t\treturn 0;\n \n \t/* Need the first folio to be able to set up the op. */\n \tfolio = writeback_iter(mapping, wbc, NULL, \u0026error);\n@@ -588,13 +582,13 @@ int netfs_writepages(struct address_space *mapping,\n \t\t}\n \n \t\terror = netfs_write_folio(wreq, wbc, folio);\n-\t\tif (error \u003c 0)\n-\t\t\tbreak;\n+\t\tif (error == -ENOMEM) {\n+\t\t\tfolio_redirty_for_writepage(wbc, folio);\n+\t\t\tfolio_unlock(folio);\n+\t\t}\n \t} while ((folio = writeback_iter(mapping, wbc, folio, \u0026error)));\n \n \tnetfs_end_issue_write(wreq);\n-\n-\tmutex_unlock(\u0026ictx-\u003ewb_lock);\n \tnetfs_wake_collector(wreq);\n \n \tnetfs_put_request(wreq, netfs_rreq_trace_put_return);\n@@ -602,9 +596,16 @@ int netfs_writepages(struct address_space *mapping,\n \treturn error;\n \n couldnt_start:\n-\tnetfs_kill_dirty_pages(mapping, wbc, folio);\n+\tif (error == -ENOMEM) {\n+\t\tfolio_redirty_for_writepage(wbc, folio);\n+\t\tfolio_unlock(folio);\n+\t\tfolio = writeback_iter(mapping, wbc, folio, \u0026error);\n+\t\tWARN_ON_ONCE(folio != NULL);\n+\t} else {\n+\t\tnetfs_kill_dirty_pages(mapping, wbc, folio);\n+\t}\n out:\n-\tmutex_unlock(\u0026ictx-\u003ewb_lock);\n+\tnetfs_wb_end(ictx);\n \t_leave(\" = %d\", error);\n \treturn error;\n }\n@@ -618,16 +619,17 @@ struct netfs_io_request *netfs_begin_writethrough(struct kiocb *iocb, size_t len\n \tstruct netfs_io_request *wreq = NULL;\n \tstruct netfs_inode *ictx = netfs_inode(file_inode(iocb-\u003eki_filp));\n \n-\tmutex_lock(\u0026ictx-\u003ewb_lock);\n+\tnetfs_wb_begin(ictx, false);\n \n \twreq = netfs_create_write_req(iocb-\u003eki_filp-\u003ef_mapping, iocb-\u003eki_filp,\n \t\t\t\t      iocb-\u003eki_pos, NETFS_WRITETHROUGH);\n \tif (IS_ERR(wreq)) {\n-\t\tmutex_unlock(\u0026ictx-\u003ewb_lock);\n+\t\tnetfs_wb_end(ictx);\n \t\treturn wreq;\n \t}\n \n \twreq-\u003eio_streams[0].avail = true;\n+\t__set_bit(NETFS_RREQ_OFFLOAD_COLLECTION, \u0026wreq-\u003eflags);\n \ttrace_netfs_write(wreq, netfs_write_trace_writethrough);\n \treturn wreq;\n }\n@@ -685,7 +687,6 @@ int netfs_advance_writethrough(struct netfs_io_request *wreq, struct writeback_c\n ssize_t netfs_end_writethrough(struct netfs_io_request *wreq, struct writeback_control *wbc,\n \t\t\t       struct folio *writethrough_cache)\n {\n-\tstruct netfs_inode *ictx = netfs_inode(wreq-\u003einode);\n \tssize_t ret;\n \n \t_enter(\"R=%x\", wreq-\u003edebug_id);\n@@ -699,8 +700,6 @@ ssize_t netfs_end_writethrough(struct netfs_io_request *wreq, struct writeback_c\n \n \tnetfs_end_issue_write(wreq);\n \n-\tmutex_unlock(\u0026ictx-\u003ewb_lock);\n-\n \tif (wreq-\u003eiocb)\n \t\tret = -EIOCBQUEUED;\n \telse\n@@ -847,15 +846,10 @@ int netfs_writeback_single(struct address_space *mapping,\n \tif (WARN_ON_ONCE(!iov_iter_is_folioq(iter)))\n \t\treturn -EIO;\n \n-\tif (!mutex_trylock(\u0026ictx-\u003ewb_lock)) {\n-\t\tif (wbc-\u003esync_mode == WB_SYNC_NONE) {\n-\t\t\t/* The VFS will have undirtied the inode. */\n-\t\t\tnetfs_single_mark_inode_dirty(\u0026ictx-\u003einode);\n-\t\t\tnetfs_stat(\u0026netfs_n_wb_lock_skip);\n-\t\t\treturn 1;\n-\t\t}\n-\t\tnetfs_stat(\u0026netfs_n_wb_lock_wait);\n-\t\tmutex_lock(\u0026ictx-\u003ewb_lock);\n+\tif (!netfs_wb_begin(ictx, wbc-\u003esync_mode == WB_SYNC_NONE)) {\n+\t\t/* The VFS will have undirtied the inode. */\n+\t\tnetfs_single_mark_inode_dirty(\u0026ictx-\u003einode);\n+\t\treturn 1;\n \t}\n \n \twreq = netfs_create_write_req(mapping, NULL, 0, NETFS_WRITEBACK_SINGLE);\n@@ -893,7 +887,6 @@ int netfs_writeback_single(struct address_space *mapping,\n \tsmp_wmb(); /* Write lists before ALL_QUEUED. */\n \tset_bit(NETFS_RREQ_ALL_QUEUED, \u0026wreq-\u003eflags);\n \n-\tmutex_unlock(\u0026ictx-\u003ewb_lock);\n \tnetfs_wake_collector(wreq);\n \n \tnetfs_put_request(wreq, netfs_rreq_trace_put_return);\n@@ -901,7 +894,7 @@ int netfs_writeback_single(struct address_space *mapping,\n \treturn ret;\n \n couldnt_start:\n-\tmutex_unlock(\u0026ictx-\u003ewb_lock);\n+\tnetfs_wb_end(ictx);\n \t_leave(\" = %d\", ret);\n \treturn ret;\n }\ndiff --git a/include/linux/netfs.h b/include/linux/netfs.h\nindex 243c0f73793883..1bc120d61c5beb 100644\n--- a/include/linux/netfs.h\n+++ b/include/linux/netfs.h\n@@ -61,14 +61,16 @@ struct netfs_inode {\n #if IS_ENABLED(CONFIG_FSCACHE)\n \tstruct fscache_cookie\t*cache;\n #endif\n-\tstruct mutex\t\twb_lock;\t/* Writeback serialisation */\n+\tstruct list_head\twb_queue;\t/* Queue of processes wanting to do writeback */\n \tloff_t\t\t\t_remote_i_size;\t/* Size of the remote file */\n \tloff_t\t\t\t_zero_point;\t/* Size after which we assume there's no data\n \t\t\t\t\t\t * on the server */\n+\tspinlock_t\t\tlock;\t\t/* Lock covering wb_queue */\n \tatomic_t\t\tio_count;\t/* Number of outstanding reqs */\n \tunsigned long\t\tflags;\n #define NETFS_ICTX_ODIRECT\t0\t\t/* The file has DIO in progress */\n #define NETFS_ICTX_UNBUFFERED\t1\t\t/* I/O should not use the pagecache */\n+#define NETFS_ICTX_WB_LOCK\t2\t\t/* Writeback serialisation lock */\n #define NETFS_ICTX_MODIFIED_ATTR 3\t\t/* Indicate change in mtime/ctime */\n #define NETFS_ICTX_SINGLE_NO_UPLOAD 4\t\t/* Monolithic payload, cache but no upload */\n };\n@@ -462,6 +464,10 @@ int netfs_alloc_folioq_buffer(struct address_space *mapping,\n \t\t\t      size_t *_cur_size, ssize_t size, gfp_t gfp);\n void netfs_free_folioq_buffer(struct folio_queue *fq);\n \n+/* Writeback exclusion API. */\n+bool netfs_wb_begin(struct netfs_inode *ictx, bool nowait);\n+void netfs_wb_end(struct netfs_inode *ictx);\n+\n /**\n  * netfs_inode - Get the netfs inode context from the inode\n  * @inode: The inode to query\n@@ -743,7 +749,8 @@ static inline void netfs_inode_init(struct netfs_inode *ctx,\n #if IS_ENABLED(CONFIG_FSCACHE)\n \tctx-\u003ecache = NULL;\n #endif\n-\tmutex_init(\u0026ctx-\u003ewb_lock);\n+\tINIT_LIST_HEAD(\u0026ctx-\u003ewb_queue);\n+\tspin_lock_init(\u0026ctx-\u003elock);\n \t/* -\u003ereleasepage() drives zero_point */\n \tif (use_zero_point) {\n \t\tctx-\u003e_zero_point = ctx-\u003e_remote_i_size;\n@@ -753,7 +760,7 @@ static inline void netfs_inode_init(struct netfs_inode *ctx,\n \n /**\n  * netfs_resize_file - Note that a file got resized\n- * @ctx: The netfs inode being resized\n+ * @ictx: The netfs inode being resized\n  * @new_i_size: The new file size\n  * @changed_on_server: The change was applied to the server\n  *\ndiff --git a/lib/iov_iter.c b/lib/iov_iter.c\nindex 243662af1af73f..5a6434709716e1 100644\n--- a/lib/iov_iter.c\n+++ b/lib/iov_iter.c\n@@ -1568,6 +1568,7 @@ static ssize_t iov_iter_extract_xarray_pages(struct iov_iter *i,\n \tstruct folio *folio;\n \tunsigned int nr = 0, offset;\n \tloff_t pos = i-\u003exarray_start + i-\u003eiov_offset;\n+\tbool will_alloc = !*pages;\n \tXA_STATE(xas, i-\u003exarray, pos \u003e\u003e PAGE_SHIFT);\n \n \toffset = pos \u0026 ~PAGE_MASK;\n@@ -1595,6 +1596,14 @@ static ssize_t iov_iter_extract_xarray_pages(struct iov_iter *i,\n \t}\n \trcu_read_unlock();\n \n+\tif (!nr) {\n+\t\tif (will_alloc) {\n+\t\t\tkvfree(*pages);\n+\t\t\t*pages = NULL;\n+\t\t}\n+\t\treturn 0;\n+\t}\n+\n \tmaxsize = min_t(size_t, nr * PAGE_SIZE - offset, maxsize);\n \tiov_iter_advance(i, maxsize);\n \treturn maxsize;\n@@ -1628,6 +1637,8 @@ static ssize_t iov_iter_extract_bvec_pages(struct iov_iter *i,\n \tbi.bi_bvec_done = skip;\n \n \tmaxpages = want_pages_array(pages, maxsize, skip, maxpages);\n+\tif (!maxpages)\n+\t\treturn -ENOMEM;\n \n \twhile (bi.bi_size \u0026\u0026 bi.bi_idx \u003c i-\u003enr_segs) {\n \t\tstruct bio_vec bv = bvec_iter_bvec(i-\u003ebvec, bi);\n@@ -1745,6 +1756,7 @@ static ssize_t iov_iter_extract_user_pages(struct iov_iter *i,\n \tunsigned long addr;\n \tunsigned int gup_flags = 0;\n \tsize_t offset;\n+\tbool will_alloc = !*pages;\n \tint res;\n \n \tif (i-\u003edata_source == ITER_DEST)\n@@ -1761,8 +1773,14 @@ static ssize_t iov_iter_extract_user_pages(struct iov_iter *i,\n \tif (!maxpages)\n \t\treturn -ENOMEM;\n \tres = pin_user_pages_fast(addr, maxpages, gup_flags, *pages);\n-\tif (unlikely(res \u003c= 0))\n+\tif (unlikely(res \u003c= 0)) {\n+\t\tif (will_alloc) {\n+\t\t\tkvfree(*pages);\n+\t\t\t*pages = NULL;\n+\t\t}\n \t\treturn res;\n+\t}\n+\n \tmaxsize = min_t(size_t, maxsize, res * PAGE_SIZE - offset);\n \tiov_iter_advance(i, maxsize);\n \treturn maxsize;\ndiff --git a/lib/scatterlist.c b/lib/scatterlist.c\nindex b7fe91ef35b8c6..6ea40d2e624755 100644\n--- a/lib/scatterlist.c\n+++ b/lib/scatterlist.c\n@@ -1366,6 +1366,7 @@ static ssize_t extract_xarray_to_sg(struct iov_iter *iter,\n \t\tsg_max--;\n \n \t\tmaxsize -= len;\n+\t\tstart += len;\n \t\tret += len;\n \t\tif (maxsize \u003c= 0 || sg_max == 0)\n \t\t\tbreak;\ndiff --git a/lib/tests/kunit_iov_iter.c b/lib/tests/kunit_iov_iter.c\nindex f02f7b7aa79605..e7e154f94f665f 100644\n--- a/lib/tests/kunit_iov_iter.c\n+++ b/lib/tests/kunit_iov_iter.c\n@@ -275,7 +275,7 @@ static void __init iov_kunit_copy_to_bvec(struct kunit *test)\n \tstruct page **spages, **bpages;\n \tu8 *scratch, *buffer;\n \tsize_t bufsize, npages, size, copied;\n-\tint i, b, patt;\n+\tint i, patt;\n \n \tbufsize = 0x100000;\n \tnpages = bufsize / PAGE_SIZE;\n@@ -298,10 +298,9 @@ static void __init iov_kunit_copy_to_bvec(struct kunit *test)\n \tKUNIT_EXPECT_EQ(test, iter.nr_segs, 0);\n \n \t/* Build the expected image in the scratch buffer. */\n-\tb = 0;\n \tpatt = 0;\n \tmemset(scratch, 0, bufsize);\n-\tfor (pr = bvec_test_ranges; pr-\u003efrom \u003e= 0; pr++, b++) {\n+\tfor (pr = bvec_test_ranges; pr-\u003efrom \u003e= 0; pr++) {\n \t\tu8 *p = scratch + pr-\u003epage * PAGE_SIZE;\n \n \t\tfor (i = pr-\u003efrom; i \u003c pr-\u003eto; i++)\n"
}

gemini-3.1-pro-preview

null

{
  "EnableConfigs": [
    "NETFS_SUPPORT",
    "FSCACHE",
    "CACHEFILES",
    "AFS_FS"
  ],
  "FocusSymbols": [
    "netfs_wb_begin",
    "netfs_wb_end",
    "netfs_unbuffered_write_iter",
    "netfs_unbuffered_write_iter_locked",
    "netfs_writepages",
    "netfs_writeback_single",
    "netfs_write_begin",
    "netfs_perform_write",
    "iov_iter_extract_pages",
    "extract_iter_to_sg"
  ],
  "Reasoning": "The patch modifies core netfs logic, including writeback locking, unbuffered writes, and iterator extraction functions. It also affects cachefiles and AFS. These changes are functional and reachable, so they should be fuzzed.",
  "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 904b94d40e085ea0bc0fb2be616a561964048287
Author: syz-cluster <triage@syzkaller.com>
Date:   Thu Jun 25 14:22:58 2026 +0000

    syz-cluster: applied patch under review

diff --git a/fs/afs/symlink.c b/fs/afs/symlink.c
index ed5868369f372d..16b4823cb7b7e7 100644
--- a/fs/afs/symlink.c
+++ b/fs/afs/symlink.c
@@ -255,11 +255,11 @@ int afs_symlink_writepages(struct address_space *mapping,
 	}
 
 	if (ret == 0) {
-		mutex_lock(&vnode->netfs.wb_lock);
+		netfs_wb_begin(&vnode->netfs, false);
 		netfs_free_folioq_buffer(vnode->directory);
 		vnode->directory = NULL;
 		vnode->directory_size = 0;
-		mutex_unlock(&vnode->netfs.wb_lock);
+		netfs_wb_end(&vnode->netfs);
 	} else if (ret == 1) {
 		ret = 0; /* Skipped write due to lock conflict. */
 	}
diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index 2937db690b40b5..d4309dfb55df4e 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -375,7 +375,7 @@ int cachefiles_bury_object(struct cachefiles_cache *cache,
 					    "Rename failed with error %d", ret);
 	}
 
-	__cachefiles_unmark_inode_in_use(object, d_inode(rep));
+	cachefiles_do_unmark_inode_in_use(object, d_inode(rep));
 	end_renaming(&rd);
 	_leave(" = 0");
 	return 0;
@@ -467,7 +467,6 @@ struct file *cachefiles_create_tmpfile(struct cachefiles_object *object)
 	ret = -EINVAL;
 	if (unlikely(!file->f_op->read_iter) ||
 	    unlikely(!file->f_op->write_iter)) {
-		fput(file);
 		pr_notice("Cache does not support read_iter and write_iter\n");
 		goto err_unuse;
 	}
diff --git a/fs/netfs/buffered_read.c b/fs/netfs/buffered_read.c
index 76d0f6a29abab2..24a8a5418e3119 100644
--- a/fs/netfs/buffered_read.c
+++ b/fs/netfs/buffered_read.c
@@ -659,7 +659,7 @@ int netfs_write_begin(struct netfs_inode *ctx,
 	 * within the cache granule containing the EOF, in which case we need
 	 * to preload the granule.
 	 */
-	if (!netfs_is_cache_enabled(ctx) &&
+	if (!netfs_is_cache_maybe_enabled(ctx) &&
 	    netfs_skip_folio_read(folio, pos, len, false)) {
 		netfs_stat(&netfs_n_rh_write_zskip);
 		goto have_folio_no_wait;
diff --git a/fs/netfs/buffered_write.c b/fs/netfs/buffered_write.c
index 6bde3320bcec66..2cdb68e6b16fff 100644
--- a/fs/netfs/buffered_write.c
+++ b/fs/netfs/buffered_write.c
@@ -277,7 +277,7 @@ ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
 		 * caching service temporarily because the backing store got
 		 * culled.
 		 */
-		if (netfs_is_cache_enabled(ctx)) {
+		if (netfs_is_cache_maybe_enabled(ctx)) {
 			if (finfo) {
 				netfs_stat(&netfs_n_wh_wstream_conflict);
 				goto flush_content;
diff --git a/fs/netfs/direct_write.c b/fs/netfs/direct_write.c
index 25f8ceb15fad64..c16fbad286a177 100644
--- a/fs/netfs/direct_write.c
+++ b/fs/netfs/direct_write.c
@@ -166,13 +166,16 @@ static int netfs_unbuffered_write(struct netfs_io_request *wreq)
 		 */
 		subreq->error = -EAGAIN;
 		trace_netfs_sreq(subreq, netfs_sreq_trace_retry);
-		if (subreq->transferred > 0)
+		if (subreq->transferred > 0) {
 			iov_iter_advance(&wreq->buffer.iter, subreq->transferred);
+			wreq->transferred += subreq->transferred;
+		}
 
 		if (stream->source == NETFS_UPLOAD_TO_SERVER &&
 		    wreq->netfs_ops->retry_request)
 			wreq->netfs_ops->retry_request(wreq, stream);
 
+		__clear_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
 		__clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
 		__clear_bit(NETFS_SREQ_BOUNDARY, &subreq->flags);
 		__clear_bit(NETFS_SREQ_FAILED, &subreq->flags);
@@ -186,17 +189,10 @@ static int netfs_unbuffered_write(struct netfs_io_request *wreq)
 
 		netfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit);
 
-		if (stream->prepare_write) {
+		if (stream->prepare_write)
 			stream->prepare_write(subreq);
-			__set_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags);
-			netfs_stat(&netfs_n_wh_retry_write_subreq);
-		} else {
-			struct iov_iter source;
-
-			netfs_reset_iter(subreq);
-			source = subreq->io_iter;
-			netfs_reissue_write(stream, subreq, &source);
-		}
+		__set_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags);
+		netfs_stat(&netfs_n_wh_retry_write_subreq);
 	}
 
 	netfs_unbuffered_write_done(wreq);
diff --git a/fs/netfs/internal.h b/fs/netfs/internal.h
index 645996ecfc8036..d889caa401dc24 100644
--- a/fs/netfs/internal.h
+++ b/fs/netfs/internal.h
@@ -239,6 +239,18 @@ static inline bool netfs_is_cache_enabled(struct netfs_inode *ctx)
 #endif
 }
 
+static inline bool netfs_is_cache_maybe_enabled(struct netfs_inode *ctx)
+{
+#if IS_ENABLED(CONFIG_FSCACHE)
+	struct fscache_cookie *cookie = ctx->cache;
+
+	return fscache_cookie_valid(cookie) &&
+		test_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags);
+#else
+	return false;
+#endif
+}
+
 /*
  * Get a ref on a netfs group attached to a dirty page (e.g. a ceph snap).
  */
diff --git a/fs/netfs/locking.c b/fs/netfs/locking.c
index 2249ecd09d0a8d..4e3be2b8150408 100644
--- a/fs/netfs/locking.c
+++ b/fs/netfs/locking.c
@@ -9,6 +9,11 @@
 #include <linux/netfs.h>
 #include "internal.h"
 
+struct netfs_wb_waiter {
+	struct list_head	link;		/* Link in ictx->wb_queue */
+	struct task_struct	*waiter;	/* Waiter task; cleared when lock granted */
+};
+
 /*
  * inode_dio_wait_interruptible - wait for outstanding DIO requests to finish
  * @inode: inode to wait for
@@ -203,3 +208,93 @@ void netfs_end_io_direct(struct inode *inode)
 	up_read(&inode->i_rwsem);
 }
 EXPORT_SYMBOL(netfs_end_io_direct);
+
+/*
+ * Wait to have exclusive access to writeback.
+ */
+static bool netfs_wb_begin_wait(struct netfs_inode *ictx)
+{
+	struct netfs_wb_waiter waiter = {};
+	struct task_struct *tsk = current;
+	bool got = false;
+
+	spin_lock(&ictx->lock);
+
+	if (test_and_set_bit_lock(NETFS_ICTX_WB_LOCK, &ictx->flags)) {
+		get_task_struct(tsk);
+		waiter.waiter = tsk;
+		list_add_tail(&waiter.link, &ictx->wb_queue);
+	} else {
+		got = true;
+	}
+	spin_unlock(&ictx->lock);
+
+	if (!got) {
+		for (;;) {
+			set_current_state(TASK_UNINTERRUPTIBLE);
+			/* Read waiter before accessing inode state. */
+			if (smp_load_acquire(&waiter.waiter) == NULL)
+				break;
+			schedule();
+		}
+	}
+	__set_current_state(TASK_RUNNING);
+	return true;
+}
+
+/**
+ * netfs_wb_begin - Begin writeback, waiting if need be
+ * @ictx: The inode to get writeback access on
+ * @nowait: Return failure immediately rather than waiting if true
+ *
+ * Begin writeback to an inode, waiting for exclusive access if @nowait is
+ * false.  This prevents collection from being done out of order with respect
+ * to the issuance of write subrequests.
+ *
+ * Note that writeback may be ended in a different process (e.g. the collection
+ * function on a workqueue) than started it.
+ *
+ * Return: True if can proceed, false if denied.
+ */
+bool netfs_wb_begin(struct netfs_inode *ictx, bool nowait)
+{
+	if (!test_and_set_bit_lock(NETFS_ICTX_WB_LOCK, &ictx->flags))
+		return true;
+	if (nowait) {
+		netfs_stat(&netfs_n_wb_lock_skip);
+		return false;
+	}
+	netfs_stat(&netfs_n_wb_lock_wait);
+	return netfs_wb_begin_wait(ictx);
+}
+EXPORT_SYMBOL(netfs_wb_begin);
+
+/* netfs_wb_end - End writeback
+ * @ictx: The inode we have writeback access to
+ *
+ * End writeback access on an inode, waking up the next writeback request.
+ */
+void netfs_wb_end(struct netfs_inode *ictx)
+{
+	struct netfs_wb_waiter *waiter;
+	struct task_struct *tsk;
+
+	WARN_ON_ONCE(!test_bit(NETFS_ICTX_WB_LOCK, &ictx->flags));
+
+	spin_lock(&ictx->lock);
+
+	waiter = list_first_entry_or_null(&ictx->wb_queue, struct netfs_wb_waiter, link);
+	if (waiter) {
+		list_del(&waiter->link);
+		tsk = waiter->waiter;
+		/* Write inode state before clearing waiter. */
+		smp_store_release(&waiter->waiter, NULL);
+		wake_up_process(tsk);
+		put_task_struct(tsk);
+	} else {
+		clear_bit_unlock(NETFS_ICTX_WB_LOCK, &ictx->flags);
+	}
+
+	spin_unlock(&ictx->lock);
+}
+EXPORT_SYMBOL(netfs_wb_end);
diff --git a/fs/netfs/write_collect.c b/fs/netfs/write_collect.c
index 24fc2bb2f8a47b..210eb8f3958d77 100644
--- a/fs/netfs/write_collect.c
+++ b/fs/netfs/write_collect.c
@@ -408,6 +408,16 @@ bool netfs_write_collection(struct netfs_io_request *wreq)
 	netfs_wake_rreq_flag(wreq, NETFS_RREQ_IN_PROGRESS, netfs_rreq_trace_wake_ip);
 	/* As we cleared NETFS_RREQ_IN_PROGRESS, we acquired its ref. */
 
+	switch (wreq->origin) {
+	case NETFS_WRITEBACK:
+	case NETFS_WRITEBACK_SINGLE:
+	case NETFS_WRITETHROUGH:
+		netfs_wb_end(ictx);
+		break;
+	default:
+		break;
+	}
+
 	if (wreq->iocb) {
 		size_t written = min(wreq->transferred, wreq->len);
 		wreq->iocb->ki_pos += written;
diff --git a/fs/netfs/write_issue.c b/fs/netfs/write_issue.c
index c03c7cc45e4716..f2761c99795a6b 100644
--- a/fs/netfs/write_issue.c
+++ b/fs/netfs/write_issue.c
@@ -106,7 +106,7 @@ struct netfs_io_request *netfs_create_write_req(struct address_space *mapping,
 	_enter("R=%x", wreq->debug_id);
 
 	ictx = netfs_inode(wreq->inode);
-	if (is_cacheable && netfs_is_cache_enabled(ictx))
+	if (is_cacheable)
 		fscache_begin_write_operation(&wreq->cache_resources, netfs_i_cookie(ictx));
 	if (rolling_buffer_init(&wreq->buffer, wreq->debug_id, ITER_SOURCE) < 0)
 		goto nomem;
@@ -551,14 +551,8 @@ int netfs_writepages(struct address_space *mapping,
 	struct folio *folio;
 	int error = 0;
 
-	if (!mutex_trylock(&ictx->wb_lock)) {
-		if (wbc->sync_mode == WB_SYNC_NONE) {
-			netfs_stat(&netfs_n_wb_lock_skip);
-			return 0;
-		}
-		netfs_stat(&netfs_n_wb_lock_wait);
-		mutex_lock(&ictx->wb_lock);
-	}
+	if (!netfs_wb_begin(ictx, wbc->sync_mode == WB_SYNC_NONE))
+		return 0;
 
 	/* Need the first folio to be able to set up the op. */
 	folio = writeback_iter(mapping, wbc, NULL, &error);
@@ -588,13 +582,13 @@ int netfs_writepages(struct address_space *mapping,
 		}
 
 		error = netfs_write_folio(wreq, wbc, folio);
-		if (error < 0)
-			break;
+		if (error == -ENOMEM) {
+			folio_redirty_for_writepage(wbc, folio);
+			folio_unlock(folio);
+		}
 	} while ((folio = writeback_iter(mapping, wbc, folio, &error)));
 
 	netfs_end_issue_write(wreq);
-
-	mutex_unlock(&ictx->wb_lock);
 	netfs_wake_collector(wreq);
 
 	netfs_put_request(wreq, netfs_rreq_trace_put_return);
@@ -602,9 +596,16 @@ int netfs_writepages(struct address_space *mapping,
 	return error;
 
 couldnt_start:
-	netfs_kill_dirty_pages(mapping, wbc, folio);
+	if (error == -ENOMEM) {
+		folio_redirty_for_writepage(wbc, folio);
+		folio_unlock(folio);
+		folio = writeback_iter(mapping, wbc, folio, &error);
+		WARN_ON_ONCE(folio != NULL);
+	} else {
+		netfs_kill_dirty_pages(mapping, wbc, folio);
+	}
 out:
-	mutex_unlock(&ictx->wb_lock);
+	netfs_wb_end(ictx);
 	_leave(" = %d", error);
 	return error;
 }
@@ -618,16 +619,17 @@ struct netfs_io_request *netfs_begin_writethrough(struct kiocb *iocb, size_t len
 	struct netfs_io_request *wreq = NULL;
 	struct netfs_inode *ictx = netfs_inode(file_inode(iocb->ki_filp));
 
-	mutex_lock(&ictx->wb_lock);
+	netfs_wb_begin(ictx, false);
 
 	wreq = netfs_create_write_req(iocb->ki_filp->f_mapping, iocb->ki_filp,
 				      iocb->ki_pos, NETFS_WRITETHROUGH);
 	if (IS_ERR(wreq)) {
-		mutex_unlock(&ictx->wb_lock);
+		netfs_wb_end(ictx);
 		return wreq;
 	}
 
 	wreq->io_streams[0].avail = true;
+	__set_bit(NETFS_RREQ_OFFLOAD_COLLECTION, &wreq->flags);
 	trace_netfs_write(wreq, netfs_write_trace_writethrough);
 	return wreq;
 }
@@ -685,7 +687,6 @@ int netfs_advance_writethrough(struct netfs_io_request *wreq, struct writeback_c
 ssize_t netfs_end_writethrough(struct netfs_io_request *wreq, struct writeback_control *wbc,
 			       struct folio *writethrough_cache)
 {
-	struct netfs_inode *ictx = netfs_inode(wreq->inode);
 	ssize_t ret;
 
 	_enter("R=%x", wreq->debug_id);
@@ -699,8 +700,6 @@ ssize_t netfs_end_writethrough(struct netfs_io_request *wreq, struct writeback_c
 
 	netfs_end_issue_write(wreq);
 
-	mutex_unlock(&ictx->wb_lock);
-
 	if (wreq->iocb)
 		ret = -EIOCBQUEUED;
 	else
@@ -847,15 +846,10 @@ int netfs_writeback_single(struct address_space *mapping,
 	if (WARN_ON_ONCE(!iov_iter_is_folioq(iter)))
 		return -EIO;
 
-	if (!mutex_trylock(&ictx->wb_lock)) {
-		if (wbc->sync_mode == WB_SYNC_NONE) {
-			/* The VFS will have undirtied the inode. */
-			netfs_single_mark_inode_dirty(&ictx->inode);
-			netfs_stat(&netfs_n_wb_lock_skip);
-			return 1;
-		}
-		netfs_stat(&netfs_n_wb_lock_wait);
-		mutex_lock(&ictx->wb_lock);
+	if (!netfs_wb_begin(ictx, wbc->sync_mode == WB_SYNC_NONE)) {
+		/* The VFS will have undirtied the inode. */
+		netfs_single_mark_inode_dirty(&ictx->inode);
+		return 1;
 	}
 
 	wreq = netfs_create_write_req(mapping, NULL, 0, NETFS_WRITEBACK_SINGLE);
@@ -893,7 +887,6 @@ int netfs_writeback_single(struct address_space *mapping,
 	smp_wmb(); /* Write lists before ALL_QUEUED. */
 	set_bit(NETFS_RREQ_ALL_QUEUED, &wreq->flags);
 
-	mutex_unlock(&ictx->wb_lock);
 	netfs_wake_collector(wreq);
 
 	netfs_put_request(wreq, netfs_rreq_trace_put_return);
@@ -901,7 +894,7 @@ int netfs_writeback_single(struct address_space *mapping,
 	return ret;
 
 couldnt_start:
-	mutex_unlock(&ictx->wb_lock);
+	netfs_wb_end(ictx);
 	_leave(" = %d", ret);
 	return ret;
 }
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index 243c0f73793883..1bc120d61c5beb 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -61,14 +61,16 @@ struct netfs_inode {
 #if IS_ENABLED(CONFIG_FSCACHE)
 	struct fscache_cookie	*cache;
 #endif
-	struct mutex		wb_lock;	/* Writeback serialisation */
+	struct list_head	wb_queue;	/* Queue of processes wanting to do writeback */
 	loff_t			_remote_i_size;	/* Size of the remote file */
 	loff_t			_zero_point;	/* Size after which we assume there's no data
 						 * on the server */
+	spinlock_t		lock;		/* Lock covering wb_queue */
 	atomic_t		io_count;	/* Number of outstanding reqs */
 	unsigned long		flags;
 #define NETFS_ICTX_ODIRECT	0		/* The file has DIO in progress */
 #define NETFS_ICTX_UNBUFFERED	1		/* I/O should not use the pagecache */
+#define NETFS_ICTX_WB_LOCK	2		/* Writeback serialisation lock */
 #define NETFS_ICTX_MODIFIED_ATTR 3		/* Indicate change in mtime/ctime */
 #define NETFS_ICTX_SINGLE_NO_UPLOAD 4		/* Monolithic payload, cache but no upload */
 };
@@ -462,6 +464,10 @@ int netfs_alloc_folioq_buffer(struct address_space *mapping,
 			      size_t *_cur_size, ssize_t size, gfp_t gfp);
 void netfs_free_folioq_buffer(struct folio_queue *fq);
 
+/* Writeback exclusion API. */
+bool netfs_wb_begin(struct netfs_inode *ictx, bool nowait);
+void netfs_wb_end(struct netfs_inode *ictx);
+
 /**
  * netfs_inode - Get the netfs inode context from the inode
  * @inode: The inode to query
@@ -743,7 +749,8 @@ static inline void netfs_inode_init(struct netfs_inode *ctx,
 #if IS_ENABLED(CONFIG_FSCACHE)
 	ctx->cache = NULL;
 #endif
-	mutex_init(&ctx->wb_lock);
+	INIT_LIST_HEAD(&ctx->wb_queue);
+	spin_lock_init(&ctx->lock);
 	/* ->releasepage() drives zero_point */
 	if (use_zero_point) {
 		ctx->_zero_point = ctx->_remote_i_size;
@@ -753,7 +760,7 @@ static inline void netfs_inode_init(struct netfs_inode *ctx,
 
 /**
  * netfs_resize_file - Note that a file got resized
- * @ctx: The netfs inode being resized
+ * @ictx: The netfs inode being resized
  * @new_i_size: The new file size
  * @changed_on_server: The change was applied to the server
  *
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 243662af1af73f..5a6434709716e1 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1568,6 +1568,7 @@ static ssize_t iov_iter_extract_xarray_pages(struct iov_iter *i,
 	struct folio *folio;
 	unsigned int nr = 0, offset;
 	loff_t pos = i->xarray_start + i->iov_offset;
+	bool will_alloc = !*pages;
 	XA_STATE(xas, i->xarray, pos >> PAGE_SHIFT);
 
 	offset = pos & ~PAGE_MASK;
@@ -1595,6 +1596,14 @@ static ssize_t iov_iter_extract_xarray_pages(struct iov_iter *i,
 	}
 	rcu_read_unlock();
 
+	if (!nr) {
+		if (will_alloc) {
+			kvfree(*pages);
+			*pages = NULL;
+		}
+		return 0;
+	}
+
 	maxsize = min_t(size_t, nr * PAGE_SIZE - offset, maxsize);
 	iov_iter_advance(i, maxsize);
 	return maxsize;
@@ -1628,6 +1637,8 @@ static ssize_t iov_iter_extract_bvec_pages(struct iov_iter *i,
 	bi.bi_bvec_done = skip;
 
 	maxpages = want_pages_array(pages, maxsize, skip, maxpages);
+	if (!maxpages)
+		return -ENOMEM;
 
 	while (bi.bi_size && bi.bi_idx < i->nr_segs) {
 		struct bio_vec bv = bvec_iter_bvec(i->bvec, bi);
@@ -1745,6 +1756,7 @@ static ssize_t iov_iter_extract_user_pages(struct iov_iter *i,
 	unsigned long addr;
 	unsigned int gup_flags = 0;
 	size_t offset;
+	bool will_alloc = !*pages;
 	int res;
 
 	if (i->data_source == ITER_DEST)
@@ -1761,8 +1773,14 @@ static ssize_t iov_iter_extract_user_pages(struct iov_iter *i,
 	if (!maxpages)
 		return -ENOMEM;
 	res = pin_user_pages_fast(addr, maxpages, gup_flags, *pages);
-	if (unlikely(res <= 0))
+	if (unlikely(res <= 0)) {
+		if (will_alloc) {
+			kvfree(*pages);
+			*pages = NULL;
+		}
 		return res;
+	}
+
 	maxsize = min_t(size_t, maxsize, res * PAGE_SIZE - offset);
 	iov_iter_advance(i, maxsize);
 	return maxsize;
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index b7fe91ef35b8c6..6ea40d2e624755 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -1366,6 +1366,7 @@ static ssize_t extract_xarray_to_sg(struct iov_iter *iter,
 		sg_max--;
 
 		maxsize -= len;
+		start += len;
 		ret += len;
 		if (maxsize <= 0 || sg_max == 0)
 			break;
diff --git a/lib/tests/kunit_iov_iter.c b/lib/tests/kunit_iov_iter.c
index f02f7b7aa79605..e7e154f94f665f 100644
--- a/lib/tests/kunit_iov_iter.c
+++ b/lib/tests/kunit_iov_iter.c
@@ -275,7 +275,7 @@ static void __init iov_kunit_copy_to_bvec(struct kunit *test)
 	struct page **spages, **bpages;
 	u8 *scratch, *buffer;
 	size_t bufsize, npages, size, copied;
-	int i, b, patt;
+	int i, patt;
 
 	bufsize = 0x100000;
 	npages = bufsize / PAGE_SIZE;
@@ -298,10 +298,9 @@ static void __init iov_kunit_copy_to_bvec(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, iter.nr_segs, 0);
 
 	/* Build the expected image in the scratch buffer. */
-	b = 0;
 	patt = 0;
 	memset(scratch, 0, bufsize);
-	for (pr = bvec_test_ranges; pr->from >= 0; pr++, b++) {
+	for (pr = bvec_test_ranges; pr->from >= 0; pr++) {
 		u8 *p = scratch + pr->page * PAGE_SIZE;
 
 		for (i = pr->from; i < pr->to; i++)

gemini-3.1-pro-preview

null

null

							input: 9401
							output: 19
							thoughts: 1030
						

**Analyzing a Patch Series: A Deep Dive**

Okay, so I've got this patch series in front of me, and it touches a significant swath of the kernel: `fs/afs/symlink.c`, `fs/cachefiles/namei.c`, a bunch of `fs/netfs/*` files (buffered read/write, direct write, internal headers, locking, write collection, issue), `include/linux/netfs.h`, and some stuff in `lib/` related to `iov_iter` and `scatterlist`, plus a KUnit test. This is definitely going to require some focused attention.

First, let's break down the changes. It looks like we're replacing some mutex-based locking in `afs/symlink.c` with a custom writeback locking mechanism using `netfs_wb_begin` and `netfs_wb_end`. That’s interesting; seems like a performance optimization or perhaps a change to handle contention better. `cachefiles/namei.c` looks like it is simplifying some inode usage tracking. Then in `fs/netfs` there is changes to cache functionality. `fs/netfs/direct_write.c` seems to be fixing a bug related to iterator advancement during direct writes, and we're seeing some cleanup of fallbacks. It looks like the main lock is changed from a mutex to a wait queue with a spinlock within. The `write_collect` and `write_issue` modules are being updated to use this new writeback locking. There are also adjustments for handling `-ENOMEM` from `netfs_write_folio`.

Moving on to `lib/`, the `iov_iter` code is getting a critical look. I see fixes related to memory management when extracting pages, ensuring proper error handling and resource cleanup, especially when `ENOMEM` is encountered. The `scatterlist` code has a small fix related to the `extract_xarray_to_sg` function. And finally the test suite has had some irrelevant variables deleted. These are all subtle, but important, changes that could impact a lot of userspace behavior.

Functionally, these changes are definitely impactful. The netfs code is core kernel logic, and the `iov_iter` and `scatterlist` changes have broad implications, not to mention the AFS changes. This looks like a fairly comprehensive set of modifications.

Based on this, this series immediately screams "fuzz me!" I'm going to want to subject this to some heavy fuzzing as there are a number of potential edge cases that could introduce bugs.

Now, let's identify the relevant configuration options. `CONFIG_NETFS_SUPPORT` is the big one, obviously. We'll need that enabled. `CONFIG_FSCACHE` is also relevant, since we're touching `cachefiles`. And since `afs/symlink.c` is being modified, `CONFIG_AFS_FS` is important, too. And of course, `CONFIG_CACHEFILES` as it impacts those functionalities directly.

Finally, I need to focus my fuzzing efforts. The key functions to target seem to be: `netfs_wb_begin`, `netfs_wb_end`, `netfs_unbuffered_write`, `netfs_writepages`, `netfs_writeback_single`, `iov_iter_extract_xarray_pages`, `iov_iter_extract_user_pages`, `iov_iter_extract_bvec_pages`, and `extract_xarray_to_sg`. I'm going to make sure that these are all covered well.

Just double-checking...yup, `CONFIG_NETFS_SUPPORT` is the linchpin. We're going to treat this with care and proceed accordingly.

{
  "Expression": "config NETFS_SUPPORT"
}

{
  "Output": "fs/netfs/Kconfig-2-\nfs/netfs/Kconfig:3:config NETFS_SUPPORT\nfs/netfs/Kconfig-4-\ttristate\n"
}

gemini-3.1-pro-preview

null

null

							input: 11306
							output: 17
							thoughts: 10
						

Okay, here's my interpretation of that thought process, tailored for an expert audience:

**Kernel Configuration Verification: `CONFIG_FSCACHE`**

Alright, time to get down to brass tacks. My initial thought is to dive into the kernel configuration. The key, of course, is `CONFIG_FSCACHE`. I need to immediately confirm the status of this particular option. Is it enabled? Is it built-in, modular, or disabled? The implications are significant depending on the setting. If it's enabled, I can then proceed with my planned troubleshooting or investigation. If not enabled, it's a completely different approach. I'll probably need to consider its dependency to other features as well. I need to know where it stands to know where to move next.

{
  "Expression": "config FSCACHE"
}

{
  "Output": "fs/netfs/Kconfig=25=config NETFS_DEBUG\n--\nfs/netfs/Kconfig-32-\nfs/netfs/Kconfig:33:config FSCACHE\nfs/netfs/Kconfig-34-\tbool \"General filesystem local caching manager\"\n--\nfs/netfs/Kconfig-43-\nfs/netfs/Kconfig:44:config FSCACHE_STATS\nfs/netfs/Kconfig-45-\tbool \"Gather statistical information on local caching\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 11627
							output: 18
							thoughts: 10
						

Here's a summary of my thought process, focusing on `CONFIG_CACHEFILES`, as a seasoned professional:

**Digging into Cachefiles**

Alright, time to dive in. My initial thought is to zero in on `CONFIG_CACHEFILES`. That's the key configuration setting here, the very foundation. I'm immediately running through the implications in my head: enabling it means the system is designed to use a caching mechanism. But what *kind* of caching? Is it block-level, file-level, or something else entirely? What filesystem is this running on? Knowing the underlying filesystem (e.g., ext4, XFS, Btrfs, etc.) is critical to understanding how the cache interacts and performs. I'm also considering the potential downsides: cache invalidation, write penalties, and overall storage overhead. This could be a performance gain, a performance *loss*, or a wash depending on numerous factors. I'm going to need more context. I want to know about the workload, the hardware, and the specific implementation before I can assess the impact of this particular setting. I want to see how this impacts my user's systems and what benefits they might be getting.

{
  "Expression": "config CACHEFILES"
}

{
  "Output": "fs/cachefiles/Kconfig-2-\nfs/cachefiles/Kconfig:3:config CACHEFILES\nfs/cachefiles/Kconfig-4-\ttristate \"Filesystem caching on files\"\n--\nfs/cachefiles/Kconfig-13-\nfs/cachefiles/Kconfig:14:config CACHEFILES_DEBUG\nfs/cachefiles/Kconfig-15-\tbool \"Debug CacheFiles\"\n--\nfs/cachefiles/Kconfig-22-\nfs/cachefiles/Kconfig:23:config CACHEFILES_ERROR_INJECTION\nfs/cachefiles/Kconfig-24-\tbool \"Provide error injection for cachefiles\"\n--\nfs/cachefiles/Kconfig-29-\nfs/cachefiles/Kconfig:30:config CACHEFILES_ONDEMAND\nfs/cachefiles/Kconfig-31-\tbool \"Support for on-demand read\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 12129
							output: 19
							thoughts: 11
						

Okay, here's my interpretation of that thought process, tailored for an expert audience, and written in the first person:

**Quick Check: AFS Configuration**

Right, let's just make sure we haven't inadvertently enabled `CONFIG_AFS_FS`. It's a quick sanity check, but a necessary one given the context. We've seen some interesting interactions lately with similar legacy filesystems, and I don't want to chase a red herring later. Best to rule it out immediately, so we can focus on the core issue. AFS has its own idiosyncrasies, and even if it's not the root cause, its presence could complicate debugging if we're dealing with something related to file system internals. Let's confirm its status and move on.

{
  "Expression": "config AFS_FS"
}

{
  "Output": "fs/afs/Kconfig-1-# SPDX-License-Identifier: GPL-2.0-only\nfs/afs/Kconfig:2:config AFS_FS\nfs/afs/Kconfig-3-\ttristate \"Andrew File System support (AFS)\"\n--\nfs/afs/Kconfig=17=config AFS_DEBUG\n--\nfs/afs/Kconfig-26-\nfs/afs/Kconfig:27:config AFS_FSCACHE\nfs/afs/Kconfig-28-\tbool \"Provide AFS client caching support\"\n"
}

gemini-3.1-pro-preview

null

null

							input: 12464
							output: 21
							thoughts: 332
						

**Analyzing Network Filesystem Writeback Operations**

Okay, let's break this down. My initial assessment points to these configurations being crucial for network file system support and caching: `NETFS_SUPPORT`, `FSCACHE`, `CACHEFILES`, and `AFS_FS`. That makes sense. I need to understand the writeback mechanisms.

My primary focus right now is on understanding the key functions involved in the write process. I'm seeing `netfs_wb_begin` and `netfs_wb_end` – those are obviously important for writeback initiation and completion. Then there's `netfs_unbuffered_write`, `netfs_writepages`, and `netfs_writeback_single` which likely deal with different write strategies. The `iov_iter_extract_...` functions are definitely interesting; I know those relate to scatter-gather I/O and page extraction, so they'll be key to how data is moved. Specifically I'm seeing `iov_iter_extract_xarray_pages`, `iov_iter_extract_user_pages`, `iov_iter_extract_bvec_pages` and `extract_xarray_to_sg` as important.

Are there any other important functions involved? Aha! Here are a few more: `netfs_write_collection`, `netfs_begin_writethrough`, `netfs_end_writethrough`, `cachefiles_bury_object`, and `cachefiles_create_tmpfile`. Those seem to be related to bulk writes, write-through consistency, and caching objects. That makes perfect sense for performance and data integrity considerations.

Now, let's see, I need to know the scope of these functions, I need to know if they're exported or static... I recall that `netfs_wb_begin` is exported, that's good. Now, looking closer, `iov_iter_extract_xarray_pages`, `iov_iter_extract_user_pages`, and `iov_iter_extract_bvec_pages` are static within `lib/iov_iter.c`. And `extract_xarray_to_sg` is static in `lib/scatterlist.c`. So they're internal.

Ah ha! `iov_iter_extract_pages` - that looks like a likely candidate for being the "master" function. It probably calls those static ones I just checked. I should check that one out.

{
  "Expression": "iov_iter_extract_pages"
}

{
  "Output": "block/bio-integrity.c=368=int bio_integrity_map_user(struct bio *bio, struct iov_iter *iter)\n--\nblock/bio-integrity.c-399-\nblock/bio-integrity.c:400:\tret = iov_iter_extract_pages(iter, \u0026pages, bytes, nr_vecs,\nblock/bio-integrity.c-401-\t\t\t\t\textraction_flags, \u0026offset);\n--\ndrivers/tee/tee_shm.c=401=register_shm_helper(struct tee_context *ctx, struct iov_iter *iter, u32 flags,\n--\ndrivers/tee/tee_shm.c-446-\ndrivers/tee/tee_shm.c:447:\tlen = iov_iter_extract_pages(iter, \u0026shm-\u003epages, LONG_MAX, num_pages, 0,\ndrivers/tee/tee_shm.c-448-\t\t\t\t     \u0026off);\n--\nfs/direct-io.c-43-/*\nfs/direct-io.c:44: * How many user pages to map in one call to iov_iter_extract_pages().  This\nfs/direct-io.c-45- * determines the size of a structure in the slab cache\n--\nfs/direct-io.c=116=struct dio {\n--\nfs/direct-io.c-128-\tspinlock_t bio_lock;\t\t/* protects BIO fields below */\nfs/direct-io.c:129:\tint page_errors;\t\t/* err from iov_iter_extract_pages() */\nfs/direct-io.c-130-\tint is_async;\t\t\t/* is IO async ? */\n--\nfs/direct-io.c=166=static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio)\n--\nfs/direct-io.c-171-\nfs/direct-io.c:172:\tret = iov_iter_extract_pages(sdio-\u003eiter, \u0026pages, LONG_MAX,\nfs/direct-io.c-173-\t\t\t\t     DIO_PAGES, 0, \u0026sdio-\u003efrom);\n--\nfs/direct-io.c-202- * Get another userspace page.  Returns an ERR_PTR on error.  Pages are\nfs/direct-io.c:203: * buffered inside the dio so that we can call iov_iter_extract_pages()\nfs/direct-io.c-204- * against a decent number of pages, less frequently.  To provide nicer use of\n--\nfs/fuse/file.c=1548=static int fuse_get_user_pages(struct fuse_args_pages *ap, struct iov_iter *ii,\n--\nfs/fuse/file.c-1559-\t * However if the implementation of fuse_conn requires pages instead of\nfs/fuse/file.c:1560:\t * pointer (e.g., virtio-fs), use iov_iter_extract_pages() instead.\nfs/fuse/file.c-1561-\t */\n--\nfs/fuse/file.c-1585-\t * Until there is support for iov_iter_extract_folios(), we have to\nfs/fuse/file.c:1586:\t * manually extract pages using iov_iter_extract_pages() and then\nfs/fuse/file.c-1587-\t * copy that to a folios array.\n--\nfs/fuse/file.c-1599-\nfs/fuse/file.c:1600:\t\tret = iov_iter_extract_pages(ii, \u0026pages,\nfs/fuse/file.c-1601-\t\t\t\t\t     *nbytesp - nbytes,\n--\nfs/netfs/iterator.c=36=ssize_t netfs_extract_user_iter(struct iov_iter *orig, size_t orig_len,\n--\nfs/netfs/iterator.c-66-\twhile (count \u0026\u0026 npages \u003c max_pages) {\nfs/netfs/iterator.c:67:\t\tret = iov_iter_extract_pages(orig, \u0026pages, count,\nfs/netfs/iterator.c-68-\t\t\t\t\t     max_pages - npages, extraction_flags,\n--\ninclude/linux/uio.h=372=static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,\n--\ninclude/linux/uio.h-387-\ninclude/linux/uio.h:388:ssize_t iov_iter_extract_pages(struct iov_iter *i, struct page ***pages,\ninclude/linux/uio.h-389-\t\t\t       size_t maxsize, unsigned int maxpages,\n--\nlib/iov_iter.c=1616=static ssize_t iov_iter_extract_bvec_pages(struct iov_iter *i,\n--\nlib/iov_iter.c-1646-\t\t/*\nlib/iov_iter.c:1647:\t\t * The iov_iter_extract_pages interface only allows an offset\nlib/iov_iter.c-1648-\t\t * into the first page.  Break out of the loop if we see an\nlib/iov_iter.c-1649-\t\t * offset into subsequent pages, the caller will have to call\nlib/iov_iter.c:1650:\t\t * iov_iter_extract_pages again for the reminder.\nlib/iov_iter.c-1651-\t\t */\n--\nlib/iov_iter.c-1668-\t\t * The caller will handle this with another call to\nlib/iov_iter.c:1669:\t\t * iov_iter_extract_pages.\nlib/iov_iter.c-1670-\t\t */\n--\nlib/iov_iter.c=1749=static ssize_t iov_iter_extract_user_pages(struct iov_iter *i,\n--\nlib/iov_iter.c-1789-/**\nlib/iov_iter.c:1790: * iov_iter_extract_pages - Extract a list of contiguous pages from an iterator\nlib/iov_iter.c-1791- * @i: The iterator to extract from\n--\nlib/iov_iter.c-1831- */\nlib/iov_iter.c:1832:ssize_t iov_iter_extract_pages(struct iov_iter *i,\nlib/iov_iter.c-1833-\t\t\t       struct page ***pages,\n--\nlib/iov_iter.c-1864-}\nlib/iov_iter.c:1865:EXPORT_SYMBOL_GPL(iov_iter_extract_pages);\nlib/iov_iter.c-1866-\nlib/iov_iter.c=1867=static unsigned int get_contig_folio_len(struct page **pages,\n--\nlib/iov_iter.c-1908- *\nlib/iov_iter.c:1909: * Like iov_iter_extract_pages(), but returns physically contiguous ranges\nlib/iov_iter.c-1910- * contained in a single folio as a single bvec instead of multiple entries.\n--\nlib/iov_iter.c=1916=ssize_t iov_iter_extract_bvecs(struct iov_iter *iter, struct bio_vec *bv,\n--\nlib/iov_iter.c-1934-\nlib/iov_iter.c:1935:\tsize = iov_iter_extract_pages(iter, \u0026pages, max_size, entries_left,\nlib/iov_iter.c-1936-\t\t\textraction_flags, \u0026offset);\n--\nlib/scatterlist.c=1113=static ssize_t extract_user_to_sg(struct iov_iter *iter,\n--\nlib/scatterlist.c-1129-\tdo {\nlib/scatterlist.c:1130:\t\tres = iov_iter_extract_pages(iter, \u0026pages, maxsize, sg_max,\nlib/scatterlist.c-1131-\t\t\t\t\t     extraction_flags, \u0026off);\n--\nlib/tests/kunit_iov_iter.c=707=static void __init iov_kunit_extract_pages_kvec(struct kunit *test)\n--\nlib/tests/kunit_iov_iter.c-734-\nlib/tests/kunit_iov_iter.c:735:\t\tlen = iov_iter_extract_pages(\u0026iter, \u0026pages, 100 * 1024,\nlib/tests/kunit_iov_iter.c-736-\t\t\t\t\t     ARRAY_SIZE(pagelist), 0, \u0026offset0);\n--\nlib/tests/kunit_iov_iter.c=787=static void __init iov_kunit_extract_pages_bvec(struct kunit *test)\n--\nlib/tests/kunit_iov_iter.c-812-\nlib/tests/kunit_iov_iter.c:813:\t\tlen = iov_iter_extract_pages(\u0026iter, \u0026pages, 100 * 1024,\nlib/tests/kunit_iov_iter.c-814-\t\t\t\t\t     ARRAY_SIZE(pagelist), 0, \u0026offset0);\n--\nlib/tests/kunit_iov_iter.c=865=static void __init iov_kunit_extract_pages_folioq(struct kunit *test)\n--\nlib/tests/kunit_iov_iter.c-896-\nlib/tests/kunit_iov_iter.c:897:\t\t\tlen = iov_iter_extract_pages(\u0026iter, \u0026pages, 100 * 1024,\nlib/tests/kunit_iov_iter.c-898-\t\t\t\t\t\t     ARRAY_SIZE(pagelist), 0, \u0026offset0);\n--\nlib/tests/kunit_iov_iter.c=944=static void __init iov_kunit_extract_pages_xarray(struct kunit *test)\n--\nlib/tests/kunit_iov_iter.c-974-\nlib/tests/kunit_iov_iter.c:975:\t\t\tlen = iov_iter_extract_pages(\u0026iter, \u0026pages, 100 * 1024,\nlib/tests/kunit_iov_iter.c-976-\t\t\t\t\t\t     ARRAY_SIZE(pagelist), 0, \u0026offset0);\n--\nnet/core/skbuff.c=7370=ssize_t skb_splice_from_iter(struct sk_buff *skb, struct iov_iter *iter,\n--\nnet/core/skbuff.c-7389-\nnet/core/skbuff.c:7390:\t\tlen = iov_iter_extract_pages(iter, \u0026ppages, maxsize, nr, 0, \u0026off);\nnet/core/skbuff.c-7391-\t\tif (len \u003c= 0) {\n--\nnet/tls/tls_device.c=421=static int tls_push_data(struct sock *sk,\n--\nnet/tls/tls_device.c-500-\nnet/tls/tls_device.c:501:\t\t\trc = iov_iter_extract_pages(iter, \u0026pages,\nnet/tls/tls_device.c-502-\t\t\t\t\t\t    copy, 1, 0, \u0026off);\n--\nnet/tls/tls_sw.c=1015=static int tls_sw_sendmsg_splice(struct sock *sk, struct msghdr *msg,\n--\nnet/tls/tls_sw.c-1024-\nnet/tls/tls_sw.c:1025:\t\tpart = iov_iter_extract_pages(\u0026msg-\u003emsg_iter, \u0026pages,\nnet/tls/tls_sw.c-1026-\t\t\t\t\t      try_to_copy, 1, 0, \u0026off);\n"
}

gemini-3.1-pro-preview

null

null

							input: 16309
							output: 21
							thoughts: 68
						

Here's my summary, as though I'm thinking through this process:

**Reflecting on Kernel Symbol Export and Static Function Handling**

Okay, so I'm looking at how we're dealing with these I/O vector iteration functions. It seems like `iov_iter_extract_pages` is the public-facing function; the one that actually gets exported and used externally. Makes sense. It acts as the wrapper for the lower-level, static functions underneath. Therefore, adding that to the focus symbols makes perfect sense, to get a handle on the key entry point.

Now, I'm noting that `extract_xarray_to_sg` is a static function. That means it's internal to this particular compilation unit. But it *is* called by `extract_iter_to_sg`. So it's still playing a crucial role, just not a globally visible one. Keep that dependency in mind as I build out the dependency graph.

{
  "Expression": "extract_iter_to_sg"
}

{
  "Output": "crypto/af_alg.c=909=int af_alg_sendmsg(struct socket *sock, struct msghdr *msg, size_t size,\n--\ncrypto/af_alg.c-1026-\ncrypto/af_alg.c:1027:\t\t\tplen = extract_iter_to_sg(\u0026msg-\u003emsg_iter, len, \u0026sgtable,\ncrypto/af_alg.c-1028-\t\t\t\t\t\t  MAX_SGL_ENTS - sgl-\u003ecur, 0);\n--\ncrypto/af_alg.c=1211=int af_alg_get_rsgl(struct sock *sk, struct msghdr *msg, int flags,\n--\ncrypto/af_alg.c-1248-\t\tsg_init_table(rsgl-\u003esgl.sgt.sgl, ALG_MAX_PAGES);\ncrypto/af_alg.c:1249:\t\terr = extract_iter_to_sg(\u0026msg-\u003emsg_iter, seglen, \u0026rsgl-\u003esgl.sgt,\ncrypto/af_alg.c-1250-\t\t\t\t\t ALG_MAX_PAGES, 0);\n--\ncrypto/algif_hash.c=63=static int hash_sendmsg(struct socket *sock, struct msghdr *msg,\n--\ncrypto/algif_hash.c-118-\ncrypto/algif_hash.c:119:\t\terr = extract_iter_to_sg(\u0026msg-\u003emsg_iter, LONG_MAX,\ncrypto/algif_hash.c-120-\t\t\t\t\t \u0026ctx-\u003esgl.sgt, npages, 0);\n--\nfs/smb/client/smb2ops.c=4387=static void *smb2_get_aead_req(struct crypto_aead *tfm, struct smb_rqst *rqst,\n--\nfs/smb/client/smb2ops.c-4421-\nfs/smb/client/smb2ops.c:4422:\t\trc = extract_iter_to_sg(iter, count, \u0026sgtable,\nfs/smb/client/smb2ops.c-4423-\t\t\t\t\tnum_sgs - sgtable.nents, 0);\n--\nfs/smb/smbdirect/mr.c=241=static int smbdirect_iter_to_sgt(struct iov_iter *iter,\n--\nfs/smb/smbdirect/mr.c-248-\nfs/smb/smbdirect/mr.c:249:\tret = extract_iter_to_sg(iter, iov_iter_count(iter), sgt, max_sg, 0);\nfs/smb/smbdirect/mr.c-250-\tWARN_ON(ret \u003c 0);\n--\ninclude/linux/uio.h=417=struct sg_table;\ninclude/linux/uio.h:418:ssize_t extract_iter_to_sg(struct iov_iter *iter, size_t len,\ninclude/linux/uio.h-419-\t\t\t   struct sg_table *sgtable, unsigned int sg_max,\n--\nlib/scatterlist.c=1335=static ssize_t extract_xarray_to_sg(struct iov_iter *iter,\n--\nlib/scatterlist.c-1381-/**\nlib/scatterlist.c:1382: * extract_iter_to_sg - Extract pages from an iterator and add to an sglist\nlib/scatterlist.c-1383- * @iter: The iterator to extract from\n--\nlib/scatterlist.c-1408- */\nlib/scatterlist.c:1409:ssize_t extract_iter_to_sg(struct iov_iter *iter, size_t maxsize,\nlib/scatterlist.c-1410-\t\t\t   struct sg_table *sgtable, unsigned int sg_max,\n--\nlib/scatterlist.c-1438-}\nlib/scatterlist.c:1439:EXPORT_SYMBOL_GPL(extract_iter_to_sg);\n--\nlib/tests/kunit_iov_iter.c=1076=iov_kunit_iter_to_sg_check(struct kunit *test, struct iov_iter *iter,\n--\nlib/tests/kunit_iov_iter.c-1088-\nlib/tests/kunit_iov_iter.c:1089:\ti = extract_iter_to_sg(iter, bufsize, data-\u003esgt, 0, 0);\nlib/tests/kunit_iov_iter.c-1090-\tKUNIT_ASSERT_EQ(test, i, 0);\n--\nlib/tests/kunit_iov_iter.c-1092-\nlib/tests/kunit_iov_iter.c:1093:\ti = extract_iter_to_sg(iter, bufsize - tail, data-\u003esgt, 1, 0);\nlib/tests/kunit_iov_iter.c-1094-\tKUNIT_ASSERT_LE(test, i, bufsize - tail);\n--\nlib/tests/kunit_iov_iter.c-1096-\nlib/tests/kunit_iov_iter.c:1097:\ti += extract_iter_to_sg(iter, bufsize - tail - i, data-\u003esgt,\nlib/tests/kunit_iov_iter.c-1098-\t\t\t\tdata-\u003enpages - data-\u003esgt-\u003enents, 0);\n--\nlib/tests/kunit_iov_iter.c-1101-\nlib/tests/kunit_iov_iter.c:1102:\ti += extract_iter_to_sg(iter, tail, data-\u003esgt,\nlib/tests/kunit_iov_iter.c-1103-\t\t\t\tdata-\u003enpages - data-\u003esgt-\u003enents, 0);\n"
}

gemini-3.1-pro-preview

null

null

							input: 18067
							output: 21
							thoughts: 155
						

**Analyzing the `extract_iter_to_sg` Function**

Okay, so `extract_iter_to_sg` is the key function we're dealing with, the one that's exported. I need to understand its context within the network filesystem writeback path. My brain's already making associations... let's see, what functions does this interact with?

Alright, let's start by looking closely at `netfs_wb_begin`, `netfs_wb_end`, `netfs_unbuffered_write`, `netfs_writepages`, and `netfs_writeback_single`. These functions seem like natural companions. I need to grasp how data gets prepped, written, and finalized within the netfs context. I'm going to pay particularly close attention to how these functions utilize or interact with `iov_iter_extract_pages`, as that’s a likely parallel function and I need to ensure I am up to date with best practice.

First off, I need to verify whether `netfs_unbuffered_write` is exported or static. That'll inform how widely available it is and whether it's the primary entry point for unbuffered writes. This gives me a clearer picture of how it fits into the overall architecture.

{
  "Expression": "netfs_unbuffered_write"
}

{
  "Output": "Documentation/filesystems/netfs_library.rst=371=filesystem is called through the standard VFS read/write_iter methods::\n--\nDocumentation/filesystems/netfs_library.rst-376-\tssize_t netfs_unbuffered_read_iter(struct kiocb *iocb, struct iov_iter *iter);\nDocumentation/filesystems/netfs_library.rst:377:\tssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from);\nDocumentation/filesystems/netfs_library.rst-378-\n--\nDocumentation/filesystems/netfs_library.rst=397=There are three functions for writes::\n--\nDocumentation/filesystems/netfs_library.rst-402-\t\t\t\t    struct netfs_group *netfs_group);\nDocumentation/filesystems/netfs_library.rst:403:\tssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *iter,\nDocumentation/filesystems/netfs_library.rst-404-\t\t\t\t\t\t   struct netfs_group *netfs_group);\n--\nfs/9p/vfs_file.c=401=v9fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)\n--\nfs/9p/vfs_file.c-408-\tif (fid-\u003emode \u0026 (P9L_DIRECT | P9L_NOWRITECACHE))\nfs/9p/vfs_file.c:409:\t\treturn netfs_unbuffered_write_iter(iocb, from);\nfs/9p/vfs_file.c-410-\n--\nfs/netfs/buffered_write.c=501=ssize_t netfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)\n--\nfs/netfs/buffered_write.c-514-\t    test_bit(NETFS_ICTX_UNBUFFERED, \u0026ictx-\u003eflags))\nfs/netfs/buffered_write.c:515:\t\treturn netfs_unbuffered_write_iter(iocb, from);\nfs/netfs/buffered_write.c-516-\n--\nfs/netfs/direct_write.c-14- */\nfs/netfs/direct_write.c:15:static void netfs_unbuffered_write_done(struct netfs_io_request *wreq)\nfs/netfs/direct_write.c-16-{\n--\nfs/netfs/direct_write.c-64- */\nfs/netfs/direct_write.c:65:static void netfs_unbuffered_write_collect(struct netfs_io_request *wreq,\nfs/netfs/direct_write.c-66-\t\t\t\t\t   struct netfs_io_stream *stream,\n--\nfs/netfs/direct_write.c-93- */\nfs/netfs/direct_write.c:94:static int netfs_unbuffered_write(struct netfs_io_request *wreq)\nfs/netfs/direct_write.c-95-{\n--\nfs/netfs/direct_write.c-150-\t\tif (!retry) {\nfs/netfs/direct_write.c:151:\t\t\tnetfs_unbuffered_write_collect(wreq, stream, subreq);\nfs/netfs/direct_write.c-152-\t\t\tsubreq = NULL;\n--\nfs/netfs/direct_write.c-197-\nfs/netfs/direct_write.c:198:\tnetfs_unbuffered_write_done(wreq);\nfs/netfs/direct_write.c-199-\t_leave(\" = %d\", ret);\n--\nfs/netfs/direct_write.c-202-\nfs/netfs/direct_write.c:203:static void netfs_unbuffered_write_async(struct work_struct *work)\nfs/netfs/direct_write.c-204-{\n--\nfs/netfs/direct_write.c-206-\nfs/netfs/direct_write.c:207:\tnetfs_unbuffered_write(wreq);\nfs/netfs/direct_write.c-208-\tnetfs_put_request(wreq, netfs_rreq_trace_put_complete);\n--\nfs/netfs/direct_write.c-214- */\nfs/netfs/direct_write.c:215:ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *iter,\nfs/netfs/direct_write.c-216-\t\t\t\t\t\t  struct netfs_group *netfs_group)\n--\nfs/netfs/direct_write.c-284-\tif (async) {\nfs/netfs/direct_write.c:285:\t\tINIT_WORK(\u0026wreq-\u003ework, netfs_unbuffered_write_async);\nfs/netfs/direct_write.c-286-\t\twreq-\u003eiocb = iocb;\n--\nfs/netfs/direct_write.c-289-\t} else {\nfs/netfs/direct_write.c:290:\t\tret = netfs_unbuffered_write(wreq);\nfs/netfs/direct_write.c-291-\t\tif (ret \u003c 0) {\n--\nfs/netfs/direct_write.c-307-}\nfs/netfs/direct_write.c:308:EXPORT_SYMBOL(netfs_unbuffered_write_iter_locked);\nfs/netfs/direct_write.c-309-\nfs/netfs/direct_write.c-310-/**\nfs/netfs/direct_write.c:311: * netfs_unbuffered_write_iter - Unbuffered write to a file\nfs/netfs/direct_write.c-312- * @iocb: IO state structure\n--\nfs/netfs/direct_write.c-322- */\nfs/netfs/direct_write.c:323:ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from)\nfs/netfs/direct_write.c-324-{\n--\nfs/netfs/direct_write.c-381-\t\t\t   FSCACHE_INVAL_DIO_WRITE);\nfs/netfs/direct_write.c:382:\tret = netfs_unbuffered_write_iter_locked(iocb, from, NULL);\nfs/netfs/direct_write.c-383-out:\n--\nfs/netfs/direct_write.c-386-}\nfs/netfs/direct_write.c:387:EXPORT_SYMBOL(netfs_unbuffered_write_iter);\n--\nfs/smb/client/file.c=2997=ssize_t cifs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)\n--\nfs/smb/client/file.c-3004-\tif (iocb-\u003eki_filp-\u003ef_flags \u0026 O_DIRECT) {\nfs/smb/client/file.c:3005:\t\twritten = netfs_unbuffered_write_iter(iocb, from);\nfs/smb/client/file.c-3006-\t\tif (written \u003e 0 \u0026\u0026 CIFS_CACHE_READ(cinode)) {\n--\nfs/smb/client/file.c=3361=static int cifs_swap_rw(struct kiocb *iocb, struct iov_iter *iter)\n--\nfs/smb/client/file.c-3367-\telse\nfs/smb/client/file.c:3368:\t\tret = netfs_unbuffered_write_iter_locked(iocb, iter, NULL);\nfs/smb/client/file.c-3369-\tif (ret \u003c 0)\n--\ninclude/linux/netfs.h=401=ssize_t netfs_buffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *from,\ninclude/linux/netfs.h-402-\t\t\t\t\t struct netfs_group *netfs_group);\ninclude/linux/netfs.h:403:ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from);\ninclude/linux/netfs.h:404:ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *iter,\ninclude/linux/netfs.h-405-\t\t\t\t\t   struct netfs_group *netfs_group);\n"
}

gemini-3.1-pro-preview

null

null

							input: 20706
							output: 19
							thoughts: 74
						

Okay, here's my interpretation of those thoughts, tailored for an expert audience:

**Focusing the Lens: `netfs_unbuffered_write_iter` and `netfs_unbuffered_write_iter_locked`**

Right, so `netfs_unbuffered_write_iter` and its locked counterpart, `netfs_unbuffered_write_iter_locked`, are already exported. Given that, it makes perfect sense to add them specifically to the focus symbols. We need to zero in on the relevant bits, and including these functions will definitely sharpen our view of the unbuffered write path. This seems like a crucial step in understanding the flow.

Now, let's just make sure we check `netfs_writepages`. It's a key function related to write operations, and we can compare and contrast the different approaches. We can use it as a reference, or as a contrasting view of the write process, in order to enhance our understanding.

{
  "Expression": "netfs_writepages"
}

{
  "Output": "Documentation/filesystems/netfs_library.rst=460=for it to intervene at various times::\n--\nDocumentation/filesystems/netfs_library.rst-463-\tint netfs_read_folio(struct file *, struct folio *);\nDocumentation/filesystems/netfs_library.rst:464:\tint netfs_writepages(struct address_space *mapping,\nDocumentation/filesystems/netfs_library.rst-465-\t\t\t     struct writeback_control *wbc);\n--\nfs/9p/vfs_addr.c=160=const struct address_space_operations v9fs_addr_operations = {\n--\nfs/9p/vfs_addr.c-166-\t.direct_IO\t\t= noop_direct_IO,\nfs/9p/vfs_addr.c:167:\t.writepages\t\t= netfs_writepages,\nfs/9p/vfs_addr.c-168-\t.migrate_folio\t\t= filemap_migrate_folio,\n--\nfs/afs/write.c=228=int afs_writepages(struct address_space *mapping, struct writeback_control *wbc)\n--\nfs/afs/write.c-241-\nfs/afs/write.c:242:\tret = netfs_writepages(mapping, wbc);\nfs/afs/write.c-243-\tup_read(\u0026vnode-\u003evalidate_lock);\n--\nfs/netfs/write_issue.c=522=static void netfs_end_issue_write(struct netfs_io_request *wreq)\n--\nfs/netfs/write_issue.c-545- */\nfs/netfs/write_issue.c:546:int netfs_writepages(struct address_space *mapping,\nfs/netfs/write_issue.c-547-\t\t     struct writeback_control *wbc)\n--\nfs/netfs/write_issue.c-611-}\nfs/netfs/write_issue.c:612:EXPORT_SYMBOL(netfs_writepages);\nfs/netfs/write_issue.c-613-\n--\nfs/smb/client/file.c=3374=const struct address_space_operations cifs_addr_ops = {\n--\nfs/smb/client/file.c-3376-\t.readahead\t= netfs_readahead,\nfs/smb/client/file.c:3377:\t.writepages\t= netfs_writepages,\nfs/smb/client/file.c-3378-\t.dirty_folio\t= netfs_dirty_folio,\n--\nfs/smb/client/file.c=3397=const struct address_space_operations cifs_addr_ops_smallbuf = {\nfs/smb/client/file.c-3398-\t.read_folio\t= netfs_read_folio,\nfs/smb/client/file.c:3399:\t.writepages\t= netfs_writepages,\nfs/smb/client/file.c-3400-\t.dirty_folio\t= netfs_dirty_folio,\n--\ninclude/linux/netfs.h=419=int netfs_write_begin(struct netfs_inode *, struct file *,\n--\ninclude/linux/netfs.h-421-\t\t      struct folio **, void **fsdata);\ninclude/linux/netfs.h:422:int netfs_writepages(struct address_space *mapping,\ninclude/linux/netfs.h-423-\t\t     struct writeback_control *wbc);\n"
}

gemini-3.1-pro-preview

null

null

							input: 21909
							output: 21
							thoughts: 24
						

Here's my thought process, as if I were analyzing that kernel code snippet:

**Diving into the Network Filesystem Writeback**

Okay, `netfs_writepages` is exported, meaning it's a critical function for handling write operations within a network filesystem. Interesting. I need to understand the writeback process. Let's dig deeper. The next logical step is to examine `netfs_writeback_single`. That should be the atomic unit, the fundamental building block within the overall writeback scheme. Understanding how a *single* page gets flushed is key to grasping the architecture's efficiency and potential bottlenecks. This likely offers insights into how individual data blocks are transmitted over the network and any associated buffering or caching strategies used at the client or server. Let's see if this `netfs_writeback_single` function gives us a better picture of how `netfs_writepages` operates in practice.

{
  "Expression": "netfs_writeback_single"
}

{
  "Output": "Documentation/filesystems/netfs_library.rst=436=a single RPC (and not written back) and is maintained as a monolithic blob\n--\nDocumentation/filesystems/netfs_library.rst-440-\tvoid netfs_single_mark_inode_dirty(struct inode *inode);\nDocumentation/filesystems/netfs_library.rst:441:\tint netfs_writeback_single(struct address_space *mapping,\nDocumentation/filesystems/netfs_library.rst-442-\t\t\t\t   struct writeback_control *wbc,\n--\nfs/afs/dir.c=2201=static int afs_dir_writepages(struct address_space *mapping,\n--\nfs/afs/dir.c-2222-\t\t\t\t     i_size_read(\u0026dvnode-\u003enetfs.inode));\nfs/afs/dir.c:2223:\t\tret = netfs_writeback_single(mapping, wbc, \u0026iter);\nfs/afs/dir.c-2224-\t\tif (ret == 1)\n--\nfs/afs/symlink.c=234=int afs_symlink_writepages(struct address_space *mapping,\n--\nfs/afs/symlink.c-253-\t\t\t\t     i_size_read(\u0026vnode-\u003enetfs.inode));\nfs/afs/symlink.c:254:\t\tret = netfs_writeback_single(mapping, wbc, \u0026iter);\nfs/afs/symlink.c-255-\t}\n--\nfs/netfs/write_issue.c=714=static int netfs_write_folio_single(struct netfs_io_request *wreq,\n--\nfs/netfs/write_issue.c-824-/**\nfs/netfs/write_issue.c:825: * netfs_writeback_single - Write back a monolithic payload\nfs/netfs/write_issue.c-826- * @mapping: The mapping to write from\n--\nfs/netfs/write_issue.c-835- */\nfs/netfs/write_issue.c:836:int netfs_writeback_single(struct address_space *mapping,\nfs/netfs/write_issue.c-837-\t\t\t   struct writeback_control *wbc,\n--\nfs/netfs/write_issue.c-900-}\nfs/netfs/write_issue.c:901:EXPORT_SYMBOL(netfs_writeback_single);\n--\ninclude/linux/netfs.h=410=ssize_t netfs_read_single(struct inode *inode, struct file *file, struct iov_iter *iter);\ninclude/linux/netfs.h:411:int netfs_writeback_single(struct address_space *mapping,\ninclude/linux/netfs.h-412-\t\t\t   struct writeback_control *wbc,\n"
}

gemini-3.1-pro-preview

null

null

							input: 22864
							output: 20
							thoughts: 25
						

Here's my summary, as though I'm thinking through this process:

**Diving into the NetFS Writeback Mechanism**

Okay, so `netfs_writeback_single` is exported, meaning it's a critical function, potentially involved in some core network file system operations. My mind immediately jumps to `cachefiles_bury_object`. If that's relevant, there's a good reason to investigate how it works with writeback. My experience suggests that this function will be instrumental. This is because I understand how network caching works. And thus, I'll start with this assumption.

{
  "Expression": "cachefiles_bury_object"
}

{
  "Output": "fs/cachefiles/interface.c=392=static bool cachefiles_invalidate_cookie(struct fscache_cookie *cookie)\n--\nfs/cachefiles/interface.c-435-\t\t\tif (!IS_ERR(obj))\nfs/cachefiles/interface.c:436:\t\t\t\tcachefiles_bury_object(volume-\u003ecache, object,\nfs/cachefiles/interface.c-437-\t\t\t\t\t\t       fan, obj,\n--\nfs/cachefiles/internal.h=276=extern void cachefiles_unmark_inode_in_use(struct cachefiles_object *object,\nfs/cachefiles/internal.h-277-\t\t\t\t\t   struct file *file);\nfs/cachefiles/internal.h:278:extern int cachefiles_bury_object(struct cachefiles_cache *cache,\nfs/cachefiles/internal.h-279-\t\t\t\t  struct cachefiles_object *object,\n--\nfs/cachefiles/namei.c=231=static int cachefiles_unlink(struct cachefiles_cache *cache,\n--\nfs/cachefiles/namei.c-268- */\nfs/cachefiles/namei.c:269:int cachefiles_bury_object(struct cachefiles_cache *cache,\nfs/cachefiles/namei.c-270-\t\t\t   struct cachefiles_object *object,\n--\nfs/cachefiles/namei.c=588=bool cachefiles_look_up_object(struct cachefiles_object *object)\n--\nfs/cachefiles/namei.c-617-\t\telse\nfs/cachefiles/namei.c:618:\t\t\tret = cachefiles_bury_object(volume-\u003ecache, object,\nfs/cachefiles/namei.c-619-\t\t\t\t\t\t     fan, de,\n--\nfs/cachefiles/namei.c=758=int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,\n--\nfs/cachefiles/namei.c-785-\t/*\nfs/cachefiles/namei.c:786:\t * cachefiles_bury_object() expects 2 references to 'victim',\nfs/cachefiles/namei.c-787-\t * and drops one.\n--\nfs/cachefiles/namei.c-789-\tdget(victim);\nfs/cachefiles/namei.c:790:\tret = cachefiles_bury_object(cache, NULL, dir, victim,\nfs/cachefiles/namei.c-791-\t\t\t\t     FSCACHE_OBJECT_WAS_CULLED);\n--\nfs/cachefiles/volume.c=18=void cachefiles_acquire_volume(struct fscache_volume *vcookie)\n--\nfs/cachefiles/volume.c-63-\t\t\tif (!IS_ERR(vdentry))\nfs/cachefiles/volume.c:64:\t\t\t\tcachefiles_bury_object(cache, NULL, cache-\u003estore,\nfs/cachefiles/volume.c-65-\t\t\t\t\t\t       vdentry,\n"
}

gemini-3.1-pro-preview

null

null

							input: 23778
							output: 21
							thoughts: 22
						

Here's my summary, as though I'm thinking through this process:

**Diving into the Cachefiles Internal Mechanics**

Okay, so we're talking about something internal to cachefiles, got it. My initial thought is to zero in on how the temporary files are created. That's usually a good starting point to understand the lifecycle of a file within the system. Let's start by looking closely at `cachefiles_create_tmpfile`. That function is probably where the magic happens – where the groundwork is laid for the cache file. I expect there's some interesting stuff in there, likely related to secure file naming, and resource allocation. Let’s see what we can find.

{
  "Expression": "cachefiles_create_tmpfile"
}

{
  "Output": "fs/cachefiles/interface.c=392=static bool cachefiles_invalidate_cookie(struct fscache_cookie *cookie)\n--\nfs/cachefiles/interface.c-407-\nfs/cachefiles/interface.c:408:\tnew_file = cachefiles_create_tmpfile(object);\nfs/cachefiles/interface.c-409-\tif (IS_ERR(new_file))\n--\nfs/cachefiles/internal.h=295=extern int cachefiles_check_in_use(struct cachefiles_cache *cache,\nfs/cachefiles/internal.h-296-\t\t\t\t   struct dentry *dir, char *filename);\nfs/cachefiles/internal.h:297:extern struct file *cachefiles_create_tmpfile(struct cachefiles_object *object);\nfs/cachefiles/internal.h-298-extern bool cachefiles_commit_tmpfile(struct cachefiles_cache *cache,\n--\nfs/cachefiles/namei.c=387=int cachefiles_delete_object(struct cachefiles_object *object,\n--\nfs/cachefiles/namei.c-409- */\nfs/cachefiles/namei.c:410:struct file *cachefiles_create_tmpfile(struct cachefiles_object *object)\nfs/cachefiles/namei.c-411-{\n--\nfs/cachefiles/namei.c=488=static bool cachefiles_create_file(struct cachefiles_object *object)\n--\nfs/cachefiles/namei.c-497-\nfs/cachefiles/namei.c:498:\tfile = cachefiles_create_tmpfile(object);\nfs/cachefiles/namei.c-499-\tif (IS_ERR(file))\n"
}

gemini-3.1-pro-preview

null

null

							input: 24412
							output: 20
							thoughts: 114
						

**Analyzing Cachefiles Write Operations**

Okay, so I'm diving into the internals of `cachefiles` and need to understand the write process. My primary focus right now is pinpointing the key symbols involved in writing data. From my perspective, these functions are central to understanding the flow: `netfs_wb_begin`, `netfs_wb_end`, `netfs_unbuffered_write_iter`, and its locked counterpart `netfs_unbuffered_write_iter_locked`, along with `netfs_writepages`, and `netfs_writeback_single`. I'm also including `iov_iter_extract_pages` and `extract_iter_to_sg` since these are likely related to how the data is handled during the I/O operations, especially with scatter/gather lists. Before moving on, I need to verify whether the `netfs_write_begin` function is properly exported and accessible within the context I'm working in, because it could provide additional context, or be a missing link.

{
  "Expression": "netfs_write_begin"
}

{
  "Output": "Documentation/filesystems/netfs_library.rst=476=There is also a deprecated function for filesystems that still use the\n--\nDocumentation/filesystems/netfs_library.rst-478-\nDocumentation/filesystems/netfs_library.rst:479:\tint netfs_write_begin(struct netfs_inode *inode, struct file *file,\nDocumentation/filesystems/netfs_library.rst-480-\t\t\t      struct address_space *mapping, loff_t pos, unsigned int len,\n--\nfs/ceph/addr.c=1878=static int ceph_write_begin(const struct kiocb *iocb,\n--\nfs/ceph/addr.c-1887-\nfs/ceph/addr.c:1888:\tr = netfs_write_begin(\u0026ci-\u003enetfs, file, inode-\u003ei_mapping, pos, len, foliop, NULL);\nfs/ceph/addr.c-1889-\tif (r \u003c 0)\n--\nfs/netfs/buffered_read.c=561=static bool netfs_skip_folio_read(struct folio *folio, loff_t pos, size_t len,\n--\nfs/netfs/buffered_read.c-595-/**\nfs/netfs/buffered_read.c:596: * netfs_write_begin - Helper to prepare for writing [DEPRECATED]\nfs/netfs/buffered_read.c-597- * @ctx: The netfs context\n--\nfs/netfs/buffered_read.c-627- */\nfs/netfs/buffered_read.c:628:int netfs_write_begin(struct netfs_inode *ctx,\nfs/netfs/buffered_read.c-629-\t\t      struct file *file, struct address_space *mapping,\n--\nfs/netfs/buffered_read.c-714-}\nfs/netfs/buffered_read.c:715:EXPORT_SYMBOL(netfs_write_begin);\nfs/netfs/buffered_read.c-716-\n--\ninclude/linux/netfs.h=418=int netfs_read_folio(struct file *, struct folio *);\ninclude/linux/netfs.h:419:int netfs_write_begin(struct netfs_inode *, struct file *,\ninclude/linux/netfs.h-420-\t\t      struct address_space *, loff_t pos, unsigned int len,\n"
}

gemini-3.1-pro-preview

null

null

							input: 25375
							output: 20
							thoughts: 39
						

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

**Adding `netfs_write_begin` to Focus Symbols and Verifying `netfs_perform_write` Export**

Alright, so the first thing I see is that `netfs_write_begin` *is* exported. Good, that confirms it. I need to get that added to the focus symbols right away. It's clearly a key piece of functionality, so I need to track it closely.

Now, let's move on to the next function. I need to quickly determine whether `netfs_perform_write` is exported. That's the next logical step in this analysis, and I need to confirm whether I can work with it, or need to dig deeper. I'll need to know whether I can use this function, so I'll go ahead and check that it's exported.

{
  "Expression": "netfs_perform_write"
}

{
  "Output": "Documentation/filesystems/netfs_library.rst=397=There are three functions for writes::\n--\nDocumentation/filesystems/netfs_library.rst-400-\t\t\t\t\t\t struct netfs_group *netfs_group);\nDocumentation/filesystems/netfs_library.rst:401:\tssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,\nDocumentation/filesystems/netfs_library.rst-402-\t\t\t\t    struct netfs_group *netfs_group);\n--\nfs/netfs/buffered_read.c=561=static bool netfs_skip_folio_read(struct folio *folio, loff_t pos, size_t len,\n--\nfs/netfs/buffered_read.c-624- *\nfs/netfs/buffered_read.c:625: * Note that this should be considered deprecated and netfs_perform_write()\nfs/netfs/buffered_read.c-626- * used instead.\n--\nfs/netfs/buffered_write.c=37=void netfs_update_i_size(struct netfs_inode *ctx, struct inode *inode,\n--\nfs/netfs/buffered_write.c-73-/**\nfs/netfs/buffered_write.c:74: * netfs_perform_write - Copy data into the pagecache.\nfs/netfs/buffered_write.c-75- * @iocb: The operation parameters\n--\nfs/netfs/buffered_write.c-86- */\nfs/netfs/buffered_write.c:87:ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,\nfs/netfs/buffered_write.c-88-\t\t\t    struct netfs_group *netfs_group)\n--\nfs/netfs/buffered_write.c-442-}\nfs/netfs/buffered_write.c:443:EXPORT_SYMBOL(netfs_perform_write);\nfs/netfs/buffered_write.c-444-\n--\nfs/netfs/buffered_write.c=468=ssize_t netfs_buffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *from,\n--\nfs/netfs/buffered_write.c-483-\nfs/netfs/buffered_write.c:484:\treturn netfs_perform_write(iocb, from, netfs_group);\nfs/netfs/buffered_write.c-485-}\n--\nfs/netfs/read_pgpriv2.c=19=static void netfs_pgpriv2_copy_folio(struct netfs_io_request *creq, struct folio *folio)\n--\nfs/netfs/read_pgpriv2.c-27-\nfs/netfs/read_pgpriv2.c:28:\t/* netfs_perform_write() may shift i_size around the page or from out\nfs/netfs/read_pgpriv2.c-29-\t * of the page to beyond it, but cannot move i_size into or through the\n--\nfs/netfs/write_issue.c=320=static int netfs_write_folio(struct netfs_io_request *wreq,\n--\nfs/netfs/write_issue.c-339-\nfs/netfs/write_issue.c:340:\t/* netfs_perform_write() may shift i_size around the page or from out\nfs/netfs/write_issue.c-341-\t * of the page to beyond it, but cannot move i_size into or through the\n--\ninclude/linux/netfs.h=202=enum netfs_io_origin {\n--\ninclude/linux/netfs.h-211-\tNETFS_WRITEBACK_SINGLE,\t\t/* This monolithic write was triggered by writepages */\ninclude/linux/netfs.h:212:\tNETFS_WRITETHROUGH,\t\t/* This write was made by netfs_perform_write() */\ninclude/linux/netfs.h-213-\tNETFS_UNBUFFERED_WRITE,\t\t/* This is an unbuffered write */\n--\ninclude/linux/netfs.h=396=ssize_t netfs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter);\n--\ninclude/linux/netfs.h-398-/* High-level write API */\ninclude/linux/netfs.h:399:ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,\ninclude/linux/netfs.h-400-\t\t\t    struct netfs_group *netfs_group);\n"
}

gemini-3.1-pro-preview

null

null

							input: 26798
							output: 20
							thoughts: 35
						

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

**Adding `netfs_perform_write` to the Focus List**

Alright, so `netfs_perform_write` is definitely exported, which is good. That confirms it's a legitimate entry point for write operations within the `netfs` context. Therefore, it makes perfect sense to add this to the focus symbols. This will allow for more targeted and efficient debugging or analysis, and will allow me to track the call path properly. I'll make sure to add it to the focus list immediately. Now, I need to check `netfs_write_collection`. I need to understand how the write operations are handled on a more granular level.

{
  "Expression": "netfs_write_collection"
}

{
  "Output": "fs/netfs/internal.h=193=int netfs_folio_written_back(struct folio *folio);\nfs/netfs/internal.h:194:bool netfs_write_collection(struct netfs_io_request *wreq);\nfs/netfs/internal.h:195:void netfs_write_collection_worker(struct work_struct *work);\nfs/netfs/internal.h-196-\n--\nfs/netfs/misc.c=513=ssize_t netfs_wait_for_write(struct netfs_io_request *rreq)\nfs/netfs/misc.c-514-{\nfs/netfs/misc.c:515:\treturn netfs_wait_for_in_progress(rreq, netfs_write_collection);\nfs/netfs/misc.c-516-}\n--\nfs/netfs/misc.c=562=void netfs_wait_for_paused_write(struct netfs_io_request *rreq)\nfs/netfs/misc.c-563-{\nfs/netfs/misc.c:564:\treturn netfs_wait_for_pause(rreq, netfs_write_collection);\nfs/netfs/misc.c-565-}\n--\nfs/netfs/objects.c=18=struct netfs_io_request *netfs_alloc_request(struct address_space *mapping,\n--\nfs/netfs/objects.c-66-\t} else {\nfs/netfs/objects.c:67:\t\tINIT_WORK(\u0026rreq-\u003ework, netfs_write_collection_worker);\nfs/netfs/objects.c-68-\t}\n--\nfs/netfs/write_collect.c=200=static void netfs_collect_write_results(struct netfs_io_request *wreq)\n--\nfs/netfs/write_collect.c-360- */\nfs/netfs/write_collect.c:361:bool netfs_write_collection(struct netfs_io_request *wreq)\nfs/netfs/write_collect.c-362-{\n--\nfs/netfs/write_collect.c-435-\nfs/netfs/write_collect.c:436:void netfs_write_collection_worker(struct work_struct *work)\nfs/netfs/write_collect.c-437-{\n--\nfs/netfs/write_collect.c-441-\tif (netfs_check_rreq_in_progress(rreq)) {\nfs/netfs/write_collect.c:442:\t\tif (netfs_write_collection(rreq))\nfs/netfs/write_collect.c-443-\t\t\t/* Drop the ref from the IN_PROGRESS flag. */\n"
}

gemini-3.1-pro-preview

null

null

							input: 27709
							output: 22
							thoughts: 34
						

Okay, here's my interpretation of those thoughts, summarized in the first person, assuming an expert-level understanding:

**Digging into the Netfs Write-Through Mechanism**

Alright, I'm diving into this netfs issue. It's obviously internal to the `netfs` code base – makes sense. Let's see... the problem likely centers around the write-through functionality. My first move will be to examine the interaction between `netfs_begin_writethrough` and `netfs_end_writethrough`. These are the obvious entry and exit points of the writethrough operation. I need to understand how these functions are being called, what they're doing when they're called, and what state they are changing. I need to see if the write-through flow is working as expected. I'll probably look at what parameters are being passed, and where they're being called from to get to the root of the problem.

{
  "Expression": "netfs_begin_writethrough"
}

{
  "Output": "fs/netfs/buffered_write.c=87=ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,\n--\nfs/netfs/buffered_write.c-118-\nfs/netfs/buffered_write.c:119:\t\twreq = netfs_begin_writethrough(iocb, iter-\u003ecount);\nfs/netfs/buffered_write.c-120-\t\tif (IS_ERR(wreq)) {\n--\nfs/netfs/internal.h=212=size_t netfs_advance_write(struct netfs_io_request *wreq,\n--\nfs/netfs/internal.h-214-\t\t\t   loff_t start, size_t len, bool to_eof);\nfs/netfs/internal.h:215:struct netfs_io_request *netfs_begin_writethrough(struct kiocb *iocb, size_t len);\nfs/netfs/internal.h-216-int netfs_advance_writethrough(struct netfs_io_request *wreq, struct writeback_control *wbc,\n--\nfs/netfs/write_issue.c=612=EXPORT_SYMBOL(netfs_writepages);\n--\nfs/netfs/write_issue.c-616- */\nfs/netfs/write_issue.c:617:struct netfs_io_request *netfs_begin_writethrough(struct kiocb *iocb, size_t len)\nfs/netfs/write_issue.c-618-{\n"
}

gemini-3.1-pro-preview

null

null

							input: 28370
							output: 20
							thoughts: 140
						

**Analyzing the NetFS Writeback Mechanism**

Okay, here's what I'm thinking. I'm deep inside the NetFS writeback process right now. My focus is entirely on these internal symbols: `netfs_wb_begin`, `netfs_wb_end`, `netfs_unbuffered_write_iter`, `netfs_unbuffered_write_iter_locked`, `netfs_writepages`, `netfs_writeback_single`, `netfs_write_begin`, `netfs_perform_write`, `iov_iter_extract_pages`, and `extract_iter_to_sg`. These are the key players in how NetFS handles writing data.

I need to understand the fundamental mechanics of this. First things first, I want to confirm that `netfs_wb_begin` and `netfs_wb_end` are exported. This confirms the writeback process is being called correctly. That will provide a good foundation for understanding how data is handled and flushed to storage. I need to trace the writeback path and identify the potential bottlenecks, the synchronization primitives used, and the overall efficiency of the system.

{
  "Expression": "netfs_wb_begin"
}

{
  "Output": "fs/afs/symlink.c=234=int afs_symlink_writepages(struct address_space *mapping,\n--\nfs/afs/symlink.c-257-\tif (ret == 0) {\nfs/afs/symlink.c:258:\t\tnetfs_wb_begin(\u0026vnode-\u003enetfs, false);\nfs/afs/symlink.c-259-\t\tnetfs_free_folioq_buffer(vnode-\u003edirectory);\n--\nfs/netfs/locking.c=210=EXPORT_SYMBOL(netfs_end_io_direct);\n--\nfs/netfs/locking.c-214- */\nfs/netfs/locking.c:215:static bool netfs_wb_begin_wait(struct netfs_inode *ictx)\nfs/netfs/locking.c-216-{\n--\nfs/netfs/locking.c-245-/**\nfs/netfs/locking.c:246: * netfs_wb_begin - Begin writeback, waiting if need be\nfs/netfs/locking.c-247- * @ictx: The inode to get writeback access on\n--\nfs/netfs/locking.c-258- */\nfs/netfs/locking.c:259:bool netfs_wb_begin(struct netfs_inode *ictx, bool nowait)\nfs/netfs/locking.c-260-{\n--\nfs/netfs/locking.c-267-\tnetfs_stat(\u0026netfs_n_wb_lock_wait);\nfs/netfs/locking.c:268:\treturn netfs_wb_begin_wait(ictx);\nfs/netfs/locking.c-269-}\nfs/netfs/locking.c:270:EXPORT_SYMBOL(netfs_wb_begin);\nfs/netfs/locking.c-271-\n--\nfs/netfs/write_issue.c=546=int netfs_writepages(struct address_space *mapping,\n--\nfs/netfs/write_issue.c-553-\nfs/netfs/write_issue.c:554:\tif (!netfs_wb_begin(ictx, wbc-\u003esync_mode == WB_SYNC_NONE))\nfs/netfs/write_issue.c-555-\t\treturn 0;\n--\nfs/netfs/write_issue.c=617=struct netfs_io_request *netfs_begin_writethrough(struct kiocb *iocb, size_t len)\n--\nfs/netfs/write_issue.c-621-\nfs/netfs/write_issue.c:622:\tnetfs_wb_begin(ictx, false);\nfs/netfs/write_issue.c-623-\n--\nfs/netfs/write_issue.c=836=int netfs_writeback_single(struct address_space *mapping,\n--\nfs/netfs/write_issue.c-848-\nfs/netfs/write_issue.c:849:\tif (!netfs_wb_begin(ictx, wbc-\u003esync_mode == WB_SYNC_NONE)) {\nfs/netfs/write_issue.c-850-\t\t/* The VFS will have undirtied the inode. */\n--\ninclude/linux/netfs.h=465=void netfs_free_folioq_buffer(struct folio_queue *fq);\n--\ninclude/linux/netfs.h-467-/* Writeback exclusion API. */\ninclude/linux/netfs.h:468:bool netfs_wb_begin(struct netfs_inode *ictx, bool nowait);\ninclude/linux/netfs.h-469-void netfs_wb_end(struct netfs_inode *ictx);\n"
}

gemini-3.1-pro-preview

null

null

							input: 29722
							output: 20
							thoughts: 133
						

**My Analysis of the Exported Symbols**

Okay, so the initial assessment is confirmed: these functions *are* exported. Good, that's what I expected based on the broader system design.

Now, let me solidify the list of focus symbols. It's:

*   `netfs_wb_begin`
*   `netfs_wb_end`
*   `netfs_unbuffered_write_iter`
*   `netfs_unbuffered_write_iter_locked`
*   `netfs_writepages`
*   `netfs_writeback_single`
*   `netfs_write_begin`
*   `netfs_perform_write`
*   `iov_iter_extract_pages`
*   `extract_iter_to_sg`

Just to be absolutely certain, I'll quickly double-check the export status of `netfs_wb_end`. Redundancy is key, especially when dealing with critical system calls. That's a key point that will always be in the back of my mind when I evaluate system design.

{
  "Expression": "netfs_wb_end"
}

{
  "Output": "fs/afs/symlink.c=234=int afs_symlink_writepages(struct address_space *mapping,\n--\nfs/afs/symlink.c-261-\t\tvnode-\u003edirectory_size = 0;\nfs/afs/symlink.c:262:\t\tnetfs_wb_end(\u0026vnode-\u003enetfs);\nfs/afs/symlink.c-263-\t} else if (ret == 1) {\n--\nfs/netfs/locking.c=270=EXPORT_SYMBOL(netfs_wb_begin);\nfs/netfs/locking.c-271-\nfs/netfs/locking.c:272:/* netfs_wb_end - End writeback\nfs/netfs/locking.c-273- * @ictx: The inode we have writeback access to\n--\nfs/netfs/locking.c-276- */\nfs/netfs/locking.c:277:void netfs_wb_end(struct netfs_inode *ictx)\nfs/netfs/locking.c-278-{\n--\nfs/netfs/locking.c-299-}\nfs/netfs/locking.c:300:EXPORT_SYMBOL(netfs_wb_end);\n--\nfs/netfs/write_collect.c=361=bool netfs_write_collection(struct netfs_io_request *wreq)\n--\nfs/netfs/write_collect.c-414-\tcase NETFS_WRITETHROUGH:\nfs/netfs/write_collect.c:415:\t\tnetfs_wb_end(ictx);\nfs/netfs/write_collect.c-416-\t\tbreak;\n--\nfs/netfs/write_issue.c=546=int netfs_writepages(struct address_space *mapping,\n--\nfs/netfs/write_issue.c-607-out:\nfs/netfs/write_issue.c:608:\tnetfs_wb_end(ictx);\nfs/netfs/write_issue.c-609-\t_leave(\" = %d\", error);\n--\nfs/netfs/write_issue.c=617=struct netfs_io_request *netfs_begin_writethrough(struct kiocb *iocb, size_t len)\n--\nfs/netfs/write_issue.c-626-\tif (IS_ERR(wreq)) {\nfs/netfs/write_issue.c:627:\t\tnetfs_wb_end(ictx);\nfs/netfs/write_issue.c-628-\t\treturn wreq;\n--\nfs/netfs/write_issue.c=836=int netfs_writeback_single(struct address_space *mapping,\n--\nfs/netfs/write_issue.c-896-couldnt_start:\nfs/netfs/write_issue.c:897:\tnetfs_wb_end(ictx);\nfs/netfs/write_issue.c-898-\t_leave(\" = %d\", ret);\n--\ninclude/linux/netfs.h=468=bool netfs_wb_begin(struct netfs_inode *ictx, bool nowait);\ninclude/linux/netfs.h:469:void netfs_wb_end(struct netfs_inode *ictx);\ninclude/linux/netfs.h-470-\n"
}

gemini-3.1-pro-preview

null

null

							input: 30968
							output: 27
							thoughts: 30
						

Okay, here's my take on those thoughts, framed as an expert's internal monologue:

**Checking for Exported Symbols**

Alright, the initial check confirms that's exported. Now, let's move on to the next item on my list. I need to verify whether `cachefiles_do_unmark_inode_in_use` is also exported. This is a critical point; knowing the export status is fundamental for understanding how these components interact and whether I can rely on a particular function in the context I'm investigating. Gotta be methodical about this.

{
  "Expression": "cachefiles_do_unmark_inode_in_use"
}

{
  "Output": "fs/cachefiles/namei.c=47=static void __cachefiles_unmark_inode_in_use(struct cachefiles_object *object,\n--\nfs/cachefiles/namei.c-53-\nfs/cachefiles/namei.c:54:static void cachefiles_do_unmark_inode_in_use(struct cachefiles_object *object,\nfs/cachefiles/namei.c-55-\t\t\t\t\t      struct inode *inode)\n--\nfs/cachefiles/namei.c=66=void cachefiles_unmark_inode_in_use(struct cachefiles_object *object,\n--\nfs/cachefiles/namei.c-71-\nfs/cachefiles/namei.c:72:\tcachefiles_do_unmark_inode_in_use(object, inode);\nfs/cachefiles/namei.c-73-\n--\nfs/cachefiles/namei.c=220=void cachefiles_put_directory(struct dentry *dir)\n--\nfs/cachefiles/namei.c-222-\tif (dir) {\nfs/cachefiles/namei.c:223:\t\tcachefiles_do_unmark_inode_in_use(NULL, d_inode(dir));\nfs/cachefiles/namei.c-224-\t\tdput(dir);\n--\nfs/cachefiles/namei.c=269=int cachefiles_bury_object(struct cachefiles_cache *cache,\n--\nfs/cachefiles/namei.c-377-\nfs/cachefiles/namei.c:378:\tcachefiles_do_unmark_inode_in_use(object, d_inode(rep));\nfs/cachefiles/namei.c-379-\tend_renaming(\u0026rd);\n--\nfs/cachefiles/namei.c=410=struct file *cachefiles_create_tmpfile(struct cachefiles_object *object)\n--\nfs/cachefiles/namei.c-477-err_unuse:\nfs/cachefiles/namei.c:478:\tcachefiles_do_unmark_inode_in_use(object, file_inode(file));\nfs/cachefiles/namei.c-479-\tfput(file);\n--\nfs/cachefiles/namei.c=513=static bool cachefiles_open_file(struct cachefiles_object *object,\n--\nfs/cachefiles/namei.c-579-error:\nfs/cachefiles/namei.c:580:\tcachefiles_do_unmark_inode_in_use(object, d_inode(dentry));\nfs/cachefiles/namei.c-581-\treturn false;\n"
}

gemini-3.1-pro-preview

null

null

							input: 31822
							output: 25
							thoughts: 26
						

Okay, here's my take on those thoughts, framed as an expert's internal monologue:

**Investigating a Stagnant Situation**

Alright, this feels... stuck. Things aren't moving. My gut tells me something is static, and I need to figure out *why*. Let's zero in on a potential culprit in the caching layer. I'm wondering if there's a particular function that might be contributing to this behavior. Specifically, I need to check the export status of `cachefiles_unmark_inode_in_use`. Is it even visible to the kernel module? That could easily be the source of my problem, if I can't access it. This could be a good starting point for debugging.

{
  "Expression": "cachefiles_unmark_inode_in_use"
}

{
  "Output": "fs/cachefiles/interface.c=328=static void cachefiles_clean_up_object(struct cachefiles_object *object,\n--\nfs/cachefiles/interface.c-346-\nfs/cachefiles/interface.c:347:\tcachefiles_unmark_inode_in_use(object, object-\u003efile);\nfs/cachefiles/interface.c-348-\n--\nfs/cachefiles/internal.h=271=extern struct kmem_cache *cachefiles_object_jar;\n--\nfs/cachefiles/internal.h-275- */\nfs/cachefiles/internal.h:276:extern void cachefiles_unmark_inode_in_use(struct cachefiles_object *object,\nfs/cachefiles/internal.h-277-\t\t\t\t\t   struct file *file);\n--\nfs/cachefiles/namei.c=33=static bool cachefiles_mark_inode_in_use(struct cachefiles_object *object,\n--\nfs/cachefiles/namei.c-46- */\nfs/cachefiles/namei.c:47:static void __cachefiles_unmark_inode_in_use(struct cachefiles_object *object,\nfs/cachefiles/namei.c-48-\t\t\t\t\t     struct inode *inode)\n--\nfs/cachefiles/namei.c=54=static void cachefiles_do_unmark_inode_in_use(struct cachefiles_object *object,\n--\nfs/cachefiles/namei.c-57-\tinode_lock(inode);\nfs/cachefiles/namei.c:58:\t__cachefiles_unmark_inode_in_use(object, inode);\nfs/cachefiles/namei.c-59-\tinode_unlock(inode);\n--\nfs/cachefiles/namei.c-65- */\nfs/cachefiles/namei.c:66:void cachefiles_unmark_inode_in_use(struct cachefiles_object *object,\nfs/cachefiles/namei.c-67-\t\t\t\t    struct file *file)\n--\nfs/cachefiles/namei.c=513=static bool cachefiles_open_file(struct cachefiles_object *object,\n--\nfs/cachefiles/namei.c-570-\tfscache_cookie_lookup_negative(object-\u003ecookie);\nfs/cachefiles/namei.c:571:\tcachefiles_unmark_inode_in_use(object, file);\nfs/cachefiles/namei.c-572-\tfput(file);\n"
}

gemini-3.1-pro-preview

null

null

							input: 32660
							output: 198
							thoughts: 236
						

**Analyzing Cachefiles Integration in NetFS**

Okay, so I'm digging into how cachefiles interacts with netfs internally. The core symbols I need to focus on are these write-related functions: `netfs_wb_begin`, `netfs_wb_end`, `netfs_unbuffered_write_iter`, `netfs_unbuffered_write_iter_locked`, `netfs_writepages`, `netfs_writeback_single`, `netfs_write_begin`, `netfs_perform_write`, `iov_iter_extract_pages`, and `extract_iter_to_sg`. I need to make sure I don't miss anything that's relevant to the cachefiles integration.

Just to be absolutely sure, I'll double-check if `netfs_write_begin` is actually still in use, even though it's marked as deprecated. Better safe than sorry – it's going on the list.

Now, for configuration options. I'm seeing `NETFS_SUPPORT`, `FSCACHE`, `CACHEFILES`, and `AFS_FS` as the key players here. I'll make sure there aren't any other configs that might be relevant. `CONFIG_FSCACHE_STATS` isn't needed. What about `CONFIG_CACHEFILES_ONDEMAND`? Nah, doesn't seem directly relevant to this specific integration point.

Alright, a quick sanity check: can I get away with just enabling `NETFS_SUPPORT`? Yes, looks like that's sufficient, which simplifies things. Excellent.

Now, let's document these findings.

{
  "EnableConfigs": [
    "NETFS_SUPPORT",
    "FSCACHE",
    "CACHEFILES",
    "AFS_FS"
  ],
  "FocusSymbols": [
    "netfs_wb_begin",
    "netfs_wb_end",
    "netfs_unbuffered_write_iter",
    "netfs_unbuffered_write_iter_locked",
    "netfs_writepages",
    "netfs_writeback_single",
    "netfs_write_begin",
    "netfs_perform_write",
    "iov_iter_extract_pages",
    "extract_iter_to_sg"
  ],
  "Reasoning": "The patch modifies core netfs logic, including writeback locking, unbuffered writes, and iterator extraction functions. It also affects cachefiles and AFS. These changes are functional and reachable, so they should be fuzzed.",
  "WorthFuzzing": true
}

{
  "EnableConfigs": [
    "NETFS_SUPPORT",
    "FSCACHE",
    "CACHEFILES",
    "AFS_FS"
  ],
  "FocusSymbols": [
    "netfs_wb_begin",
    "netfs_wb_end",
    "netfs_unbuffered_write_iter",
    "netfs_unbuffered_write_iter_locked",
    "netfs_writepages",
    "netfs_writeback_single",
    "netfs_write_begin",
    "netfs_perform_write",
    "iov_iter_extract_pages",
    "extract_iter_to_sg"
  ],
  "Reasoning": "The patch modifies core netfs logic, including writeback locking, unbuffered writes, and iterator extraction functions. It also affects cachefiles and AFS. These changes are functional and reachable, so they should be fuzzed.",
  "WorthFuzzing": true
}