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2026-08-24fuse: Fix the condition to enable over-io-uringBernd Schubert1-4/+0
The existing condition in fuse_uring_cmd() is there only to avoid disabling io-uring for connections that already run with it, missing was a condition to refuse any IORING_OP_URING_CMD if the connection/channel didn't get enabled because of missing FUSE_INIT reply flag FUSE_OVER_IO_URING. Without the reply flag the barrier in fuse_uring_ready() doesn't work and IO could already be going on and cause deadlock states (at a minimum one between fch->bg_lock and queue->lock). The change itself is trivial, but brings behavior change, FUSE_OVER_IO_URING has to be set in the FUSE_INIT_REPLY by fuse servers to accept any IORING_OP_URING_CMD. Libfuse does that and the only non-libfuse implementation I found (fractal-fuse) also does it. Qemu patches for fuse-io-uring are not merged yet, as far as I know. Moved up is the smp_load_acquire(&fch->initialized) check, as a fuse-server implementation might try to setup io-uring before FUSE_INIT is processed and might have gotten -EOPNOTSUPP instead of -EAGAIN. Also fixed is a stale comment that explains the handling of the FUSE_OVER_IO_URING flag in early RFC versions. If there should be a report from any library or application we probably need to revert this commit. Fixes: 3393ff964e0f ("fuse: block request allocation until io-uring init is complete") Signed-off-by: Bernd Schubert <bernd@bsbernd.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-08-18fuse: check for NULL root inode in fuse_fill_super_submountBaokun Li1-0/+2
fuse_iget() can return NULL when its inode allocation fails, but fuse_fill_super_submount() passed the result straight to get_fuse_inode() and decremented fi->nlookup without checking it: root = fuse_iget(sb, parent_fi->nodeid, ...); fi = get_fuse_inode(root); fi->nlookup--; Inside fuse_iget() the inode allocation can fail and return NULL. The submount root takes the iget5_locked() path, whose alloc_inode() can fail under memory pressure (the auto-submount branch can fail the same way in new_inode() or fuse_alloc_submount_lookup()): inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set, &nodeid); if (!inode) return NULL; A NULL root makes get_fuse_inode() a container_of() on NULL and the nlookup decrement a write to a bogus address, oopsing the mount. With CONFIG_KASAN the following null pointer dereference is reported when the root inode allocation of an auto-submount fails (e.g. under memory pressure): ================================================================== BUG: KASAN: null-ptr-deref in fuse_get_tree_submount+0x656/0x8b0 Read of size 8 at addr 00000000000002b0 by task ls/942 CPU: 0 PID: 942 Comm: ls Tainted: G W 6.6 #15 Call Trace: <TASK> fuse_get_tree_submount+0x656/0x8b0 vfs_get_tree+0x48/0x140 fc_mount+0x13/0x50 fuse_dentry_automount+0x7a/0xb0 __traverse_mounts+0xca/0x330 step_into+0x339/0xac0 path_lookupat+0xc5/0x2f0 filename_lookup+0x163/0x2a0 vfs_statx+0xd5/0x200 do_statx+0x83/0xd0 __x64_sys_statx+0xa0/0xc0 do_syscall_64+0x37/0x90 entry_SYSCALL_64_after_hwframe+0x78/0xe2 </TASK> ================================================================== Return -ENOMEM instead; the caller tears down the partially built superblock on error, matching the other error returns in this function. Fixes: 1866d779d5d2 ("fuse: Allow fuse_fill_super_common() for submounts") Signed-off-by: Baokun Li <libaokun@linux.alibaba.com> Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-08-18fuse: reject a duplicate fd= mount optionBaokun Li1-0/+3
fuse_opt_fd() stored the fuse device in ctx->fud and bumped its refcount unconditionally: ctx->fud = fuse_dev_grab(file); If fd= is given twice (two fsconfig FSCONFIG_SET_FD calls), the second call overwrites ctx->fud and grabs the new device, while the reference taken on the first device is never released - a permanent refcount leak that pins the first fuse_dev until reboot. Reject a second fd= outright. ctx is zeroed on allocation, so a non-NULL ctx->fud reliably means the option was already processed. Fixes: d42eb23b2ef9 ("fuse: don't require /dev/fuse fd to be kept open during mount") Signed-off-by: Baokun Li <libaokun@linux.alibaba.com> Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-08-17fuse: add io-uring buffer poolsJoanne Koong1-1/+1
Right now, ents and buffers are tightly coupled in fuse io-uring where each entry has its own dedicated payload buffer, requiring N buffers for N entries where each buffer must be large enough to accomodate the maximum payload size. This is suboptimal as most request types (lookup, open, release, getattr, etc) require vastly less bytes than the maximum payload size and some requests (unlink, rmdir, fsync, flush, etc) do not require payload buffers at all. Instead of requiring a 1:1 coupling between ents and payload buffers, allow the server to pass in a buffer pool (a contiguous chunk of memory) that the kernel will use as it wishes for servicing ents/requests. Entries only reserve a "buffer" from the pool while actively processing a request that requires a payload buffer. This decoupling and letting the kernel delegate memory from the pool for requests allows the kernel to optimize memory usage and reduces the memory usage requirements needed to use fuse-over-io-uring. A pool is registered per queue with the new FUSE_IO_URING_CMD_ADD_BUFPOOL command. The server passes the pool's base address and length in fuse_uring_cmd_req.bufpool.{uaddr,len}. Internally, the kernel splits the region into buffers of ring->max_payload_sz bytes each (nr_bufs = pool len / max_payload_sz). A queue commits to a payload mode on first use: registering an entry that carries its own payload selects the legacy per-entry mode, while ADD_BUFPOOL selects pool mode. The two are mutually exclusive, so ADD_BUFPOOL must be issued before any payload-carrying entries are registered on that queue. The queue must have been created before the bufpool is added, through the FUSE_IO_URING_CMD_ADD_QUEUE command. The kernel tracks free buffers with a bitmap (a set bit marks a free buffer). On dispatch, a request that needs a payload claims a free buffer (find_first_bit + clear). A request that needs none claims nothing. The buffer's byte offset within the pool is reported to the server in the new fuse_uring_ent_in_out.offset field so that the server can locate the payload. On completion the buffer is returned to the pool or reused directly if the next request on that entry also has a payload. The FUSE_HAS_IO_URING_BUFPOOL flag advertises kernel support to the server for bufpools. Buffer pool request flow ~~~~~~~~~~~~~~~~~~~~~~~~ | Kernel | FUSE daemon | | | [request arrives] | | [claim a free pool buffer] | | >fuse_uring_select_buffer() | | [copy headers to ring] | | [copy payload to buffer] | | [report buffer offset in ent_in_out] | | >io_uring_cmd_done() | | | [read headers] | | [read/write payload at offset] | | [process request] | | >io_uring_submit() | | COMMIT_AND_FETCH | >fuse_uring_commit_fetch() | | [copy reply from ring] | | [return buffer to the pool] | | >fuse_uring_recycle_buffer() | Reviewed-by: Bernd Schubert <bernd@bsbernd.com> Signed-off-by: Joanne Koong <joannelkoong@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-08-17fuse: decouple fuse_ring creation from ent registrationJoanne Koong1-1/+3
Currently, the connection's fuse_ring is created lazily on the first FUSE_IO_URING_CMD_REGISTER command. A server registers entries from one thread per queue (one per CPU) and those threads issue their first REGISTER command concurrently. They then race to create the single per-connection fuse_ring, which required open-coded handling in fuse_uring_create() to detect and protect against concurrent creations. Decouple fuse_ring creation from ent registration and move it to FUSE_INIT reply processing after a server has negotiated and set FUSE_OVER_IO_URING. The ring is published before the connection is marked initialized. fuse_uring_register() no longer creates the ring and it instead uses the ring set up at init time. Reviewed-by: Bernd Schubert <bernd@bsbernd.com> Signed-off-by: Joanne Koong <joannelkoong@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-07-17fuse: allow larger read requests by setting bdi->io_pagesJim Harris1-0/+1
A FUSE server that advertises a large max_pages and max_write (e.g. max_pages=256, max_write=1MB) cannot currently obtain matching FUSE_READ request sizes from the kernel. Buffered sequential writes arrive at the server at the negotiated max_write size, but a large buffered read() is split into several smaller FUSE_READ requests. For a buffered read, filemap_get_pages() -> page_cache_sync_ra() sizes the read against ractl_max_pages(): max_pages = ractl->ra->ra_pages; if (req_size > max_pages && bdi->io_pages > max_pages) max_pages = min(req_size, bdi->io_pages); fuse leaves bdi->io_pages at the default VM_READAHEAD_PAGES (128KB), so a 1MB read() (req_size = 256 pages) is clamped to the readahead window (128KB, or 256KB for POSIX_FADV_SEQUENTIAL), producing four 256KB FUSE_READ round-trips instead of one. Set bdi->io_pages to fc->max_pages after feature negotiation. As the code above shows, io_pages only raises the limit when the request size already exceeds the readahead window, so it enlarges explicitly requested reads without enlarging the speculative readahead window. This avoids increasing speculative page-cache readahead on behalf of an unprivileged server. NFS does the same, setting io_pages from rpages while leaving ra_pages at the default. fc->max_pages is already bounded by fc->max_pages_limit (and, for virtio-fs, by the virtqueue descriptor count), so io_pages inherits the same bound. Suggested-by: Joanne Koong <joannelkoong@gmail.com> Signed-off-by: Jim Harris <jim.harris@nvidia.com> Assisted-by: Cursor:claude-opus-4.8 Reviewed-by: Joanne Koong <joannelkoong@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-06-15fuse: Add SPDX ID lines to some filesTim Bird1-3/+1
Some fuse source files are missing SPDX-License-Identifier lines. Add appropriate IDs to these files, and remove old license references from the headers. Signed-off-by: Tim Bird <tim.bird@sony.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-06-15fuse: use QSTR() instead of QSTR_INIT() in fuse_get_dentryThorsten Blum1-2/+1
Drop the hard-coded length argument and use the simpler QSTR(). Inline the code and drop the local variable. Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-06-15fuse: drop redundant check in fuse_sync_bucket_alloc()Li Wang1-5/+3
kzalloc_obj with __GFP_NOFAIL is documented to never return failure, and checking for NULL is redundant (__GFP_NOFAIL in gfp_types.h). Signed-off-by: Li Wang <liwang@kylinos.cn> Reviewed-by: Joanne Koong <joannelkoong@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-06-15fuse: remove #include "fuse_i.h" from dev.c and dev_uring.cMiklos Szeredi1-0/+5
Move a couple of function declarations from fuse_i.h to dev.h and fuse_dev_i.h. Add fuse_conn_get_id() helper that retrieves the connection ID (s_dev) from fuse_conn. With the exception of cuse.c, virtio_fs.c and trace.c source files now either include fuse_i.h or fuse_dev_i/dev_uring_i.h but not both. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-06-15fuse: set params in fuse_chan_set_initialized()Miklos Szeredi1-2/+8
Set minor, max_write and max_pages in the fuse_chan. These match the same fields in fuse_conn but are needed in both layers. [Dongyang Jin: Pointers should use NULL instead of explicit '0'] Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-06-15fuse: change fud->fc to fud->chanMiklos Szeredi1-2/+2
Store pointer to struct fuse_chan instead of struct fuse_conn in fuse_dev. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-06-15fuse: remove fm arg of args->end callbackMiklos Szeredi1-4/+6
Only used by FUSE_INIT and CUSE_INIT, these can store the relevant pointer in their structs derived from fuse_args. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-06-15fuse: abort related layering cleanupMiklos Szeredi1-3/+3
- rename fuse_abort_conn() to fuse_chan_abort(), pass fuse_chan pointer instead of fuse_conn - pass an abort_with_err argument that tells fuse_dev_(read|write) to return with ECONNABORTED instead of ENODEV - move fc->aborted to fch->abort_with_err - rename fuse_wait_aborted() to fuse_chan_wait_aborted() Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-06-15fuse: move fuse_dev_waitq to dev.cMiklos Szeredi1-4/+2
Move wake_up_all(&fuse_dev_waitq) into fuse_dev_install() where it logically belongs. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-06-15fuse: move forget related struct and helpersMiklos Szeredi1-8/+3
Move: - struct fuse_forget_link to fuse_dev_i.h - fuse_alloc_forget() to dev.c/dev.h Rename: - fuse_queue_forget -> fuse_chan_queue_forget Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-06-15fuse: don't access transport layer structs directly from the fs layerMiklos Szeredi1-22/+14
Add helpers (get and set functions mainly) that cleanly separate the layers. Remove #include "fuse_dev_i.h" from: - inode.c - file.c - control.c Remove #include "dev_uring_i.h" from inode.c. [Li Wang: drop redundant initializer in process_init_limits()] Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-06-15fuse: move request timeout to fuse_chanMiklos Szeredi1-4/+3
Move: - timeout Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-06-15fuse: add back pointer from fuse_chan to fuse_connMiklos Szeredi1-0/+1
Will be needed by callbacks from the transport layer to the fs layer. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-06-15fuse: move io_uring related members to fuse_chanMiklos Szeredi1-1/+1
Move: - io_uring - ring Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-06-15fuse: move request blocking related members to fuse_chanMiklos Szeredi1-6/+1
Move: - initialized - blocked - blocked_waitq - connected - num_waiting Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-06-15fuse: move background queuing related members to fuse_chanMiklos Szeredi1-11/+5
Move: - max_background - num_background - active_background - bg_queue - bg_lock Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-06-15fuse: move 'devices' member from fuse_conn to fuse_chanMiklos Szeredi1-2/+0
This belongs in the transport layer. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-06-15fuse: move fuse_dev and fuse_pqueue to dev.cMiklos Szeredi1-94/+0
Move function definitions to dev.c, struct definitions to fuse_dev_i.h. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-06-15fuse: move fuse_iqueue to fuse_chanMiklos Szeredi1-23/+4
Move the 'fiq' member from fuse_conn to fuse_chan. Move iqueue related structure definitions and function declarations from "fuse_i.h" to "fuse_dev_i.h". Add a fuse_dev_chan_new() helper, that returns a fuse_chan initialized with the fuse_dev_fiq_ops. Add a fuse_chan_release() function, that calls fiq->ops->release(). Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-06-15fuse: add struct fuse_chanMiklos Szeredi1-2/+8
The goal is to separate transport layer stuff out from struct fuse_conn, leaving just the filesystem related members. Add a new object referenced from fuse_conn. This patch just implements the allocation and freeing of this object. Following patches will move transport related members from fuse_conn to fuse_chan. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-06-15fuse: move request timeout code to a new source fileMiklos Szeredi1-31/+2
This marks the first step in cleanly separating the transport layer from the filesystem layer. Add "dev.h", which will contain the interface definition for the transport layer. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-04-15Merge tag 'fuse-update-7.1' of ↵Linus Torvalds1-55/+81
git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse Pull fuse update from Miklos Szeredi: - Fix possible hang in virtiofs when cleaning up a DAX inode (Sergio Lopez) - Fix a warning when using large folio as the source of SPLICE_F_MOVE on the fuse device (Bernd) - Fix uninitialized value found by KMSAN (Luis Henriques) - Fix synchronous INIT hang (Miklos) - Fix race between inode initialization and FUSE_NOTIFY_INVAL_INODE (Horst) - Allow fd to be closed after passing fuse device fd to fsconfig(..., "fd", ...) (Miklos) - Support FSCONFIG_SET_FD for "fd" option (Miklos) - Misc fixes and cleanups * tag 'fuse-update-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse: (21 commits) fuse: support FSCONFIG_SET_FD for "fd" option fuse: clean up device cloning fuse: don't require /dev/fuse fd to be kept open during mount fuse: add refcount to fuse_dev fuse: create fuse_dev on /dev/fuse open instead of mount fuse: check connection state on notification fuse: fuse_dev_ioctl_clone() should wait for device file to be initialized fuse: fix inode initialization race fuse: abort on fatal signal during sync init fuse: fix uninit-value in fuse_dentry_revalidate() fuse: use offset_in_page() for page offset calculations fuse: use DIV_ROUND_UP() for page count calculations fuse: simplify logic in fuse_notify_store() and fuse_retrieve() fuse: validate outarg offset and size in notify store/retrieve fuse: Check for large folio with SPLICE_F_MOVE fuse: quiet down complaints in fuse_conn_limit_write fuse: drop unnecessary argument from fuse_lookup_init() fuse: fix premature writetrhough request for large folio fuse: refactor duplicate queue teardown operation virtiofs: add FUSE protocol validation ...
2026-04-02fuse: support FSCONFIG_SET_FD for "fd" optionMiklos Szeredi1-7/+11
This is not only cleaner to use in userspace (no need to sprintf the fd to a string) but also allows userspace to detect that the devfd can be closed after the fsconfig call. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
2026-04-02fuse: clean up device cloningMiklos Szeredi1-1/+0
- fuse_mutex is not needed for device cloning, because fuse_dev_install() uses cmpxcg() to set fud->fc, which prevents races between clone/mount or clone/clone. This makes the logic simpler - Drop fc->dev_count. This is only used to check in release if the device is the last clone, but checking list_empty(&fc->devices) is equivalent after removing the released device from the list. Removing the fuse_dev before calling fuse_abort_conn() is okay, since the processing and io lists are now empty for this device. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-04-02fuse: don't require /dev/fuse fd to be kept open during mountMiklos Szeredi1-24/+33
With the new mount API the sequence of syscalls would be: fs_fd = fsopen("fuse", 0); snprintf(opt, sizeof(opt), "%i", devfd); fsconfig(fs_fd, FSCONFIG_SET_STRING, "fd", opt, 0); /* ... */ fsconfig(fs_fd, FSCONFIG_CMD_CREATE, 0, 0, 0); Current mount code just stores the value of devfd in the fs_context and uses it in during FSCONFIG_CMD_CREATE, which is inelegant. Instead grab a reference to the underlying fuse_dev, and use that during the filesystem creation. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-04-02fuse: add refcount to fuse_devMiklos Szeredi1-6/+29
This will make it possible to grab the fuse_dev and subsequently release the file that it came from. In the above case, fud->fc will be set to FUSE_DEV_FC_DISCONNECTED to indicate that this is no longer a functional device. When trying to assign an fc to such a disconnected fuse_dev, the fc is set to the disconnected state. Use atomic operations xchg() and cmpxchg() to prevent races. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-04-02fuse: create fuse_dev on /dev/fuse open instead of mountMiklos Szeredi1-24/+11
Allocate struct fuse_dev when opening the device. This means that unlike before, ->private_data is always set to a valid pointer. The use of USE_DEV_SYNC_INIT magic pointer for the private_data is now replaced with a simple bool sync_init member. If sync INIT is not set, I/O on the device returns error before mount. Keep this behavior by checking for the ->fc member. If fud->fc is set, the mount has succeeded. Testing this used READ_ONCE(file->private_data) and smp_mb() to try and provide the necessary semantics. Switch this to smp_store_release() and smp_load_acquire(). Setting fud->fc is protected by fuse_mutex, this is unchanged. Will need this later so the /dev/fuse open file reference is not held during FSCONFIG_CMD_CREATE. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
2026-04-01fuse: fix inode initialization raceHorst Birthelmer1-2/+5
Fix a race between fuse_iget() and fuse_reverse_inval_inode() where invalidation can arrive while an inode is being initialized, causing the invalidation to be lost. By keeping the inode state I_NEW as long as the attributes are not valid the invalidation can wait until the inode is fully initialized. Suggested-by: Joanne Koong <joannelkoong@gmail.com> Signed-off-by: Horst Birthelmer <hbirthelmer@ddn.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-03-24fuse: abort on fatal signal during sync initMiklos Szeredi1-0/+1
When sync init is used and the server exits for some reason (error, crash) while processing FUSE_INIT, the filesystem creation will hang. The reason is that while all other threads will exit, the mounting thread (or process) will keep the device fd open, which will prevent an abort from happening. This is a regression from the async mount case, where the mount was done first, and the FUSE_INIT processing afterwards, in which case there's no such recursive syscall keeping the fd open. Fixes: dfb84c330794 ("fuse: allow synchronous FUSE_INIT") Cc: stable@vger.kernel.org # v6.18 Reviewed-by: Joanne Koong <joannelkoong@gmail.com> Reviewed-by: Bernd Schubert <bernd@bsbernd.com> Reviewed-by: "Darrick J. Wong" <djwong@kernel.org> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2026-03-20writeback: don't block sync for filesystems with no data integrity guaranteesJoanne Koong1-0/+1
Add a SB_I_NO_DATA_INTEGRITY superblock flag for filesystems that cannot guarantee data persistence on sync (eg fuse). For superblocks with this flag set, sync kicks off writeback of dirty inodes but does not wait for the flusher threads to complete the writeback. This replaces the per-inode AS_NO_DATA_INTEGRITY mapping flag added in commit f9a49aa302a0 ("fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes()"). The flag belongs at the superblock level because data integrity is a filesystem-wide property, not a per-inode one. Having this flag at the superblock level also allows us to skip having to iterate every dirty inode in wait_sb_inodes() only to skip each inode individually. Prior to this commit, mappings with no data integrity guarantees skipped waiting on writeback completion but still waited on the flusher threads to finish initiating the writeback. Waiting on the flusher threads is unnecessary. This commit kicks off writeback but does not wait on the flusher threads. This change properly addresses a recent report [1] for a suspend-to-RAM hang seen on fuse-overlayfs that was caused by waiting on the flusher threads to finish: Workqueue: pm_fs_sync pm_fs_sync_work_fn Call Trace: <TASK> __schedule+0x457/0x1720 schedule+0x27/0xd0 wb_wait_for_completion+0x97/0xe0 sync_inodes_sb+0xf8/0x2e0 __iterate_supers+0xdc/0x160 ksys_sync+0x43/0xb0 pm_fs_sync_work_fn+0x17/0xa0 process_one_work+0x193/0x350 worker_thread+0x1a1/0x310 kthread+0xfc/0x240 ret_from_fork+0x243/0x280 ret_from_fork_asm+0x1a/0x30 </TASK> On fuse this is problematic because there are paths that may cause the flusher thread to block (eg if systemd freezes the user session cgroups first, which freezes the fuse daemon, before invoking the kernel suspend. The kernel suspend triggers ->write_node() which on fuse issues a synchronous setattr request, which cannot be processed since the daemon is frozen. Or if the daemon is buggy and cannot properly complete writeback, initiating writeback on a dirty folio already under writeback leads to writeback_get_folio() -> folio_prepare_writeback() -> unconditional wait on writeback to finish, which will cause a hang). This commit restores fuse to its prior behavior before tmp folios were removed, where sync was essentially a no-op. [1] https://lore.kernel.org/linux-fsdevel/CAJnrk1a-asuvfrbKXbEwwDSctvemF+6zfhdnuzO65Pt8HsFSRw@mail.gmail.com/T/#m632c4648e9cafc4239299887109ebd880ac6c5c1 Fixes: 0c58a97f919c ("fuse: remove tmp folio for writebacks and internal rb tree") Reported-by: John <therealgraysky@proton.me> Cc: stable@vger.kernel.org Signed-off-by: Joanne Koong <joannelkoong@gmail.com> Link: https://patch.msgid.link/20260320005145.2483161-2-joannelkoong@gmail.com Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: David Hildenbrand (Arm) <david@kernel.org> Signed-off-by: Christian Brauner <brauner@kernel.org>
2026-02-21Convert 'alloc_obj' family to use the new default GFP_KERNEL argumentLinus Torvalds1-6/+6
This was done entirely with mindless brute force, using git grep -l '\<k[vmz]*alloc_objs*(.*, GFP_KERNEL)' | xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/' to convert the new alloc_obj() users that had a simple GFP_KERNEL argument to just drop that argument. Note that due to the extreme simplicity of the scripting, any slightly more complex cases spread over multiple lines would not be triggered: they definitely exist, but this covers the vast bulk of the cases, and the resulting diff is also then easier to check automatically. For the same reason the 'flex' versions will be done as a separate conversion. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2026-02-21treewide: Replace kmalloc with kmalloc_obj for non-scalar typesKees Cook1-10/+10
This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook <kees@kernel.org>
2025-12-05Merge tag 'fuse-update-6.19' of ↵Linus Torvalds1-18/+24
git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse Pull fuse updates from Miklos Szeredi: - Add mechanism for cleaning out unused, stale dentries; controlled via a module option (Luis Henriques) - Fix various bugs - Cleanups * tag 'fuse-update-6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse: fuse: Uninitialized variable in fuse_epoch_work() fuse: fix io-uring list corruption for terminated non-committed requests fuse: signal that a fuse inode should exhibit local fs behaviors fuse: Always flush the page cache before FOPEN_DIRECT_IO write fuse: Invalidate the page cache after FOPEN_DIRECT_IO write fuse: rename 'namelen' to 'namesize' fuse: use strscpy instead of strcpy fuse: refactor fuse_conn_put() to remove negative logic. fuse: new work queue to invalidate dentries from old epochs fuse: new work queue to periodically invalidate expired dentries dcache: export shrink_dentry_list() and add new helper d_dispose_if_unused() fuse: add WARN_ON and comment for RCU revalidate fuse: Fix whitespace for fuse_uring_args_to_ring() comment fuse: missing copy_finish in fuse-over-io-uring argument copies fuse: fix readahead reclaim deadlock
2025-12-01Merge tag 'vfs-6.19-rc1.inode' of ↵Linus Torvalds1-2/+2
git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs Pull vfs inode updates from Christian Brauner: "Features: - Hide inode->i_state behind accessors. Open-coded accesses prevent asserting they are done correctly. One obvious aspect is locking, but significantly more can be checked. For example it can be detected when the code is clearing flags which are already missing, or is setting flags when it is illegal (e.g., I_FREEING when ->i_count > 0) - Provide accessors for ->i_state, converts all filesystems using coccinelle and manual conversions (btrfs, ceph, smb, f2fs, gfs2, overlayfs, nilfs2, xfs), and makes plain ->i_state access fail to compile - Rework I_NEW handling to operate without fences, simplifying the code after the accessor infrastructure is in place Cleanups: - Move wait_on_inode() from writeback.h to fs.h - Spell out fenced ->i_state accesses with explicit smp_wmb/smp_rmb for clarity - Cosmetic fixes to LRU handling - Push list presence check into inode_io_list_del() - Touch up predicts in __d_lookup_rcu() - ocfs2: retire ocfs2_drop_inode() and I_WILL_FREE usage - Assert on ->i_count in iput_final() - Assert ->i_lock held in __iget() Fixes: - Add missing fences to I_NEW handling" * tag 'vfs-6.19-rc1.inode' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (22 commits) dcache: touch up predicts in __d_lookup_rcu() fs: push list presence check into inode_io_list_del() fs: cosmetic fixes to lru handling fs: rework I_NEW handling to operate without fences fs: make plain ->i_state access fail to compile xfs: use the new ->i_state accessors nilfs2: use the new ->i_state accessors overlayfs: use the new ->i_state accessors gfs2: use the new ->i_state accessors f2fs: use the new ->i_state accessors smb: use the new ->i_state accessors ceph: use the new ->i_state accessors btrfs: use the new ->i_state accessors Manual conversion to use ->i_state accessors of all places not covered by coccinelle Coccinelle-based conversion to use ->i_state accessors fs: provide accessors for ->i_state fs: spell out fenced ->i_state accesses with explicit smp_wmb/smp_rmb fs: move wait_on_inode() from writeback.h to fs.h fs: add missing fences to I_NEW handling ocfs2: retire ocfs2_drop_inode() and I_WILL_FREE usage ...
2025-11-12fuse: refactor fuse_conn_put() to remove negative logic.Luis Henriques1-19/+20
There is no functional change with this patch. It simply refactors function fuse_conn_put() to not use negative logic, which makes it more easier to read. Signed-off-by: Luis Henriques <luis@igalia.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2025-11-12fuse: new work queue to invalidate dentries from old epochsLuis Henriques1-0/+2
With the infrastructure introduced to periodically invalidate expired dentries, it is now possible to add an extra work queue to invalidate dentries when an epoch is incremented. This work queue will only be triggered when the 'inval_wq' parameter is set. Signed-off-by: Luis Henriques <luis@igalia.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2025-11-12fuse: new work queue to periodically invalidate expired dentriesLuis Henriques1-0/+3
This patch adds the necessary infrastructure to keep track of all dentries created for FUSE file systems. A set of rbtrees, protected by hashed locks, will be used to keep all these dentries sorted by expiry time. A new module parameter 'inval_wq' is also added. When set, it will start a work queue which will periodically invalidate expired dentries. The value of this new parameter is the period, in seconds, for this work queue. Once this parameter is set, every new dentry will be added to one of the rbtrees. When the work queue is executed, it will check all the rbtrees and will invalidate those dentries that have timed-out. The work queue period can not be smaller than 5 seconds, but can be disabled by setting 'inval_wq' to zero (which is the default). Signed-off-by: Luis Henriques <luis@igalia.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2025-11-05fuse: remove fc->blkbits workaround for partial writesJoanne Koong1-12/+1
Now that fuse is integrated with iomap for read/readahead, we can remove the workaround that was added in commit bd24d2108e9c ("fuse: fix fuseblk i_blkbits for iomap partial writes"), which was previously needed to avoid a race condition where an iomap partial write may be overwritten by a read if blocksize < PAGE_SIZE. Now that fuse does iomap read/readahead, this is protected against since there is granular uptodate tracking of blocks, which means this workaround can be removed. Signed-off-by: Joanne Koong <joannelkoong@gmail.com> Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Christian Brauner <brauner@kernel.org>
2025-10-20Coccinelle-based conversion to use ->i_state accessorsMateusz Guzik1-2/+2
All places were patched by coccinelle with the default expecting that ->i_lock is held, afterwards entries got fixed up by hand to use unlocked variants as needed. The script: @@ expression inode, flags; @@ - inode->i_state & flags + inode_state_read(inode) & flags @@ expression inode, flags; @@ - inode->i_state &= ~flags + inode_state_clear(inode, flags) @@ expression inode, flag1, flag2; @@ - inode->i_state &= ~flag1 & ~flag2 + inode_state_clear(inode, flag1 | flag2) @@ expression inode, flags; @@ - inode->i_state |= flags + inode_state_set(inode, flags) @@ expression inode, flags; @@ - inode->i_state = flags + inode_state_assign(inode, flags) @@ expression inode, flags; @@ - flags = inode->i_state + flags = inode_state_read(inode) @@ expression inode, flags; @@ - READ_ONCE(inode->i_state) & flags + inode_state_read(inode) & flags Signed-off-by: Mateusz Guzik <mjguzik@gmail.com> Signed-off-by: Christian Brauner <brauner@kernel.org>
2025-10-03Merge tag 'fuse-update-6.18' of ↵Linus Torvalds1-19/+57
git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse Pull fuse updates from Miklos Szeredi: - Extend copy_file_range interface to be fully 64bit capable (Miklos) - Add selftest for fusectl (Chen Linxuan) - Move fuse docs into a separate directory (Bagas Sanjaya) - Allow fuse to enter freezable state in some cases (Sergey Senozhatsky) - Clean up writeback accounting after removing tmp page copies (Joanne) - Optimize virtiofs request handling (Li RongQing) - Add synchronous FUSE_INIT support (Miklos) - Allow server to request prune of unused inodes (Miklos) - Fix deadlock with AIO/sync release (Darrick) - Add some prep patches for block/iomap support (Darrick) - Misc fixes and cleanups * tag 'fuse-update-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse: (26 commits) fuse: move CREATE_TRACE_POINTS to a separate file fuse: move the backing file idr and code into a new source file fuse: enable FUSE_SYNCFS for all fuseblk servers fuse: capture the unique id of fuse commands being sent fuse: fix livelock in synchronous file put from fuseblk workers mm: fix lockdep issues in writeback handling fuse: add prune notification fuse: remove redundant calls to fuse_copy_finish() in fuse_notify() fuse: fix possibly missing fuse_copy_finish() call in fuse_notify() fuse: remove FUSE_NOTIFY_CODE_MAX from <uapi/linux/fuse.h> fuse: remove fuse_readpages_end() null mapping check fuse: fix references to fuse.rst -> fuse/fuse.rst fuse: allow synchronous FUSE_INIT fuse: zero initialize inode private data fuse: remove unused 'inode' parameter in fuse_passthrough_open virtio_fs: fix the hash table using in virtio_fs_enqueue_req() mm: remove BDI_CAP_WRITEBACK_ACCT fuse: use default writeback accounting virtio_fs: Remove redundant spinlock in virtio_fs_request_complete() fuse: remove unneeded offset assignment when filling write pages ...
2025-09-29Merge tag 'vfs-6.18-rc1.workqueue' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs Pull vfs workqueue updates from Christian Brauner: "This contains various workqueue changes affecting the filesystem layer. Currently if a user enqueue a work item using schedule_delayed_work() the used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to schedule_work() that is using system_wq and queue_work(), that makes use again of WORK_CPU_UNBOUND. This replaces the use of system_wq and system_unbound_wq. system_wq is a per-CPU workqueue which isn't very obvious from the name and system_unbound_wq is to be used when locality is not required. So this renames system_wq to system_percpu_wq, and system_unbound_wq to system_dfl_wq. This also adds a new WQ_PERCPU flag to allow the fs subsystem users to explicitly request the use of per-CPU behavior. Both WQ_UNBOUND and WQ_PERCPU flags coexist for one release cycle to allow callers to transition their calls. WQ_UNBOUND will be removed in a next release cycle" * tag 'vfs-6.18-rc1.workqueue' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: fs: WQ_PERCPU added to alloc_workqueue users fs: replace use of system_wq with system_percpu_wq fs: replace use of system_unbound_wq with system_dfl_wq
2025-09-29Merge tag 'vfs-6.18-rc1.misc' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs Pull misc vfs updates from Christian Brauner: "This contains the usual selections of misc updates for this cycle. Features: - Add "initramfs_options" parameter to set initramfs mount options. This allows to add specific mount options to the rootfs to e.g., limit the memory size - Add RWF_NOSIGNAL flag for pwritev2() Add RWF_NOSIGNAL flag for pwritev2. This flag prevents the SIGPIPE signal from being raised when writing on disconnected pipes or sockets. The flag is handled directly by the pipe filesystem and converted to the existing MSG_NOSIGNAL flag for sockets - Allow to pass pid namespace as procfs mount option Ever since the introduction of pid namespaces, procfs has had very implicit behaviour surrounding them (the pidns used by a procfs mount is auto-selected based on the mounting process's active pidns, and the pidns itself is basically hidden once the mount has been constructed) This implicit behaviour has historically meant that userspace was required to do some special dances in order to configure the pidns of a procfs mount as desired. Examples include: * In order to bypass the mnt_too_revealing() check, Kubernetes creates a procfs mount from an empty pidns so that user namespaced containers can be nested (without this, the nested containers would fail to mount procfs) But this requires forking off a helper process because you cannot just one-shot this using mount(2) * Container runtimes in general need to fork into a container before configuring its mounts, which can lead to security issues in the case of shared-pidns containers (a privileged process in the pidns can interact with your container runtime process) While SUID_DUMP_DISABLE and user namespaces make this less of an issue, the strict need for this due to a minor uAPI wart is kind of unfortunate Things would be much easier if there was a way for userspace to just specify the pidns they want. So this pull request contains changes to implement a new "pidns" argument which can be set using fsconfig(2): fsconfig(procfd, FSCONFIG_SET_FD, "pidns", NULL, nsfd); fsconfig(procfd, FSCONFIG_SET_STRING, "pidns", "/proc/self/ns/pid", 0); or classic mount(2) / mount(8): // mount -t proc -o pidns=/proc/self/ns/pid proc /tmp/proc mount("proc", "/tmp/proc", "proc", MS_..., "pidns=/proc/self/ns/pid"); Cleanups: - Remove the last references to EXPORT_OP_ASYNC_LOCK - Make file_remove_privs_flags() static - Remove redundant __GFP_NOWARN when GFP_NOWAIT is used - Use try_cmpxchg() in start_dir_add() - Use try_cmpxchg() in sb_init_done_wq() - Replace offsetof() with struct_size() in ioctl_file_dedupe_range() - Remove vfs_ioctl() export - Replace rwlock() with spinlock in epoll code as rwlock causes priority inversion on preempt rt kernels - Make ns_entries in fs/proc/namespaces const - Use a switch() statement() in init_special_inode() just like we do in may_open() - Use struct_size() in dir_add() in the initramfs code - Use str_plural() in rd_load_image() - Replace strcpy() with strscpy() in find_link() - Rename generic_delete_inode() to inode_just_drop() and generic_drop_inode() to inode_generic_drop() - Remove unused arguments from fcntl_{g,s}et_rw_hint() Fixes: - Document @name parameter for name_contains_dotdot() helper - Fix spelling mistake - Always return zero from replace_fd() instead of the file descriptor number - Limit the size for copy_file_range() in compat mode to prevent a signed overflow - Fix debugfs mount options not being applied - Verify the inode mode when loading it from disk in minixfs - Verify the inode mode when loading it from disk in cramfs - Don't trigger automounts with RESOLVE_NO_XDEV If openat2() was called with RESOLVE_NO_XDEV it didn't traverse through automounts, but could still trigger them - Add FL_RECLAIM flag to show_fl_flags() macro so it appears in tracepoints - Fix unused variable warning in rd_load_image() on s390 - Make INITRAMFS_PRESERVE_MTIME depend on BLK_DEV_INITRD - Use ns_capable_noaudit() when determining net sysctl permissions - Don't call path_put() under namespace semaphore in listmount() and statmount()" * tag 'vfs-6.18-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (38 commits) fcntl: trim arguments listmount: don't call path_put() under namespace semaphore statmount: don't call path_put() under namespace semaphore pid: use ns_capable_noaudit() when determining net sysctl permissions fs: rename generic_delete_inode() and generic_drop_inode() init: INITRAMFS_PRESERVE_MTIME should depend on BLK_DEV_INITRD initramfs: Replace strcpy() with strscpy() in find_link() initrd: Use str_plural() in rd_load_image() initramfs: Use struct_size() helper to improve dir_add() initrd: Fix unused variable warning in rd_load_image() on s390 fs: use the switch statement in init_special_inode() fs/proc/namespaces: make ns_entries const filelock: add FL_RECLAIM to show_fl_flags() macro eventpoll: Replace rwlock with spinlock selftests/proc: add tests for new pidns APIs procfs: add "pidns" mount option pidns: move is-ancestor logic to helper openat2: don't trigger automounts with RESOLVE_NO_XDEV namei: move cross-device check to __traverse_mounts namei: remove LOOKUP_NO_XDEV check from handle_mounts ...
2025-09-23fuse: enable FUSE_SYNCFS for all fuseblk serversDarrick J. Wong1-0/+1
Turn on syncfs for all fuseblk servers so that the ones in the know can flush cached intermediate data and logs to disk. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2025-09-19fs: replace use of system_wq with system_percpu_wqMarco Crivellari1-1/+1
Currently if a user enqueue a work item using schedule_delayed_work() the used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to schedule_work() that is using system_wq and queue_work(), that makes use again of WORK_CPU_UNBOUND. This lack of consistentcy cannot be addressed without refactoring the API. system_wq is a per-CPU worqueue, yet nothing in its name tells about that CPU affinity constraint, which is very often not required by users. Make it clear by adding a system_percpu_wq to all the fs subsystem. The old wq will be kept for a few release cylces. Suggested-by: Tejun Heo <tj@kernel.org> Signed-off-by: Marco Crivellari <marco.crivellari@suse.com> Link: https://lore.kernel.org/20250916082906.77439-3-marco.crivellari@suse.com Signed-off-by: Christian Brauner <brauner@kernel.org>