kernel/linux.git/fs/fuse/inode.c, branch v6.19.12

writeback: don't block sync for filesystems with no data integrity guarantees

2026-04-02T11:25:43+00:00

commit 76f9377cd2ab7a9220c25d33940d9ca20d368172 upstream. 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: __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 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 Cc: stable@vger.kernel.org Signed-off-by: Joanne Koong Link: https://patch.msgid.link/20260320005145.2483161-2-joannelkoong@gmail.com Reviewed-by: Jan Kara Reviewed-by: David Hildenbrand (Arm) Signed-off-by: Christian Brauner Signed-off-by: Greg Kroah-Hartman

Merge tag 'fuse-update-6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse

2025-12-05T23:25:13+00:00

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

Merge tag 'vfs-6.19-rc1.inode' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2025-12-01T17:02:34+00:00

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 ...

fuse: refactor fuse_conn_put() to remove negative logic.

2025-11-12T10:45:03+00:00

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 Signed-off-by: Miklos Szeredi

fuse: new work queue to invalidate dentries from old epochs

2025-11-12T10:45:03+00:00

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 Signed-off-by: Miklos Szeredi

fuse: new work queue to periodically invalidate expired dentries

2025-11-12T10:45:03+00:00

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 Signed-off-by: Miklos Szeredi

fuse: remove fc->blkbits workaround for partial writes

2025-11-05T11:57:24+00:00

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 Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Darrick J. Wong Signed-off-by: Christian Brauner

Coccinelle-based conversion to use ->i_state accessors

2025-10-20T18:22:26+00:00

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 Signed-off-by: Christian Brauner

Merge tag 'fuse-update-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse

2025-10-03T19:48:18+00:00

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 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 ...

Merge tag 'vfs-6.18-rc1.workqueue' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2025-09-29T17:27:17+00:00

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