linux/fs/fs-writeback.c, branch v6.19

Merge tag 'vfs-6.19-rc8.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2026-01-26T17:30:48Z

Pull vfs fixes from Christian Brauner: - Fix the the buggy conversion of fuse_reverse_inval_entry() introduced during the creation rework - Disallow nfs delegation requests for directories by setting simple_nosetlease() - Require an opt-in for getting readdir flag bits outside of S_DT_MASK set in d_type - Fix scheduling delayed writeback work by only scheduling when the dirty time expiry interval is non-zero and cancel the delayed work if the interval is set to zero - Use rounded_jiffies_interval for dirty time work - Check the return value of sb_set_blocksize() for romfs - Wait for batched folios to be stable in __iomap_get_folio() - Use private naming for fuse hash size - Fix the stale dentry cleanup to prevent a race that causes a UAF * tag 'vfs-6.19-rc8.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: vfs: document d_dispose_if_unused() fuse: shrink once after all buckets have been scanned fuse: clean up fuse_dentry_tree_work() fuse: add need_resched() before unlocking bucket fuse: make sure dentry is evicted if stale fuse: fix race when disposing stale dentries fuse: use private naming for fuse hash size writeback: use round_jiffies_relative for dirtytime_work iomap: wait for batched folios to be stable in __iomap_get_folio romfs: check sb_set_blocksize() return value docs: clarify that dirtytime_expire_seconds=0 disables writeback writeback: fix 100% CPU usage when dirtytime_expire_interval is 0 readdir: require opt-in for d_type flags vboxsf: don't allow delegations to be set on directories ceph: don't allow delegations to be set on directories gfs2: don't allow delegations to be set on directories 9p: don't allow delegations to be set on directories smb/client: properly disallow delegations on directories nfs: properly disallow delegation requests on directories fuse: fix conversion of fuse_reverse_inval_entry() to start_removing()

fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes()

2026-01-19T20:30:01Z

Above the while() loop in wait_sb_inodes(), we document that we must wait for all pages under writeback for data integrity. Consequently, if a mapping, like fuse, traditionally does not have data integrity semantics, there is no need to wait at all; we can simply skip these inodes. This restores fuse back to prior behavior where syncs are no-ops. This fixes a user regression where if a system is running a faulty fuse server that does not reply to issued write requests, this causes wait_sb_inodes() to wait forever. Link: https://lkml.kernel.org/r/20260105211737.4105620-2-joannelkoong@gmail.com Fixes: 0c58a97f919c ("fuse: remove tmp folio for writebacks and internal rb tree") Signed-off-by: Joanne Koong Reported-by: Athul Krishna Reported-by: J. Neuschäfer Reviewed-by: Bernd Schubert Tested-by: J. Neuschäfer Cc: Alexander Viro Cc: Bernd Schubert Cc: Bonaccorso Salvatore Cc: Christian Brauner Cc: David Hildenbrand Cc: Jan Kara Cc: "Liam R. Howlett" Cc: Lorenzo Stoakes Cc: "Matthew Wilcox (Oracle)" Cc: Michal Hocko Cc: Mike Rapoport Cc: Miklos Szeredi Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Signed-off-by: Andrew Morton

writeback: use round_jiffies_relative for dirtytime_work

2026-01-14T16:11:43Z

The dirtytime_work is a background housekeeping task that flushes dirty inodes, using round_jiffies_relative() will allow kernel to batch this work with other aligned system tasks, reducing power consumption. Signed-off-by: Zhao Mengmeng Link: https://patch.msgid.link/20260113082614.231580-1-zhaomzhao@126.com Reviewed-by: Jan Kara Signed-off-by: Christian Brauner

writeback: fix 100% CPU usage when dirtytime_expire_interval is 0

2026-01-12T10:07:25Z

When vm.dirtytime_expire_seconds is set to 0, wakeup_dirtytime_writeback() schedules delayed work with a delay of 0, causing immediate execution. The function then reschedules itself with 0 delay again, creating an infinite busy loop that causes 100% kworker CPU usage. Fix by: - Only scheduling delayed work in wakeup_dirtytime_writeback() when dirtytime_expire_interval is non-zero - Cancelling the delayed work in dirtytime_interval_handler() when the interval is set to 0 - Adding a guard in start_dirtytime_writeback() for defensive coding Tested by booting kernel in QEMU with virtme-ng: - Before fix: kworker CPU spikes to ~73% - After fix: CPU remains at normal levels - Setting interval back to non-zero correctly resumes writeback Fixes: a2f4870697a5 ("fs: make sure the timestamps for lazytime inodes eventually get written") Cc: stable@vger.kernel.org Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220227 Signed-off-by: Laveesh Bansal Link: https://patch.msgid.link/20260106145059.543282-2-laveeshb@laveeshbansal.com Reviewed-by: Jan Kara Signed-off-by: Christian Brauner

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

2025-12-01T17:20:51Z

Pull writeback updates from Christian Brauner: "Features: - Allow file systems to increase the minimum writeback chunk size. The relatively low minimal writeback size of 4MiB means that written back inodes on rotational media are switched a lot. Besides introducing additional seeks, this also can lead to extreme file fragmentation on zoned devices when a lot of files are cached relative to the available writeback bandwidth. This adds a superblock field that allows the file system to override the default size, and sets it to the zone size for zoned XFS. - Add logging for slow writeback when it exceeds sysctl_hung_task_timeout_secs. This helps identify tasks waiting for a long time and pinpoint potential issues. Recording the starting jiffies is also useful when debugging a crashed vmcore. - Wake up waiting tasks when finishing the writeback of a chunk Cleanups: - filemap_* writeback interface cleanups. Adding filemap_fdatawrite_wbc ended up being a mistake, as all but the original btrfs caller should be using better high level interfaces instead. This series removes all these low-level interfaces, switches btrfs to a more specific interface, and cleans up other too low-level interfaces. With this the writeback_control that is passed to the writeback code is only initialized in three places. - Remove __filemap_fdatawrite, __filemap_fdatawrite_range, and filemap_fdatawrite_wbc - Add filemap_flush_nr helper for btrfs - Push struct writeback_control into start_delalloc_inodes in btrfs - Rename filemap_fdatawrite_range_kick to filemap_flush_range - Stop opencoding filemap_fdatawrite_range in 9p, ocfs2, and mm - Make wbc_to_tag() inline and use it in fs" * tag 'vfs-6.19-rc1.writeback' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: fs: Make wbc_to_tag() inline and use it in fs. xfs: set s_min_writeback_pages for zoned file systems writeback: allow the file system to override MIN_WRITEBACK_PAGES writeback: cleanup writeback_chunk_size mm: rename filemap_fdatawrite_range_kick to filemap_flush_range mm: remove __filemap_fdatawrite_range mm: remove filemap_fdatawrite_wbc mm: remove __filemap_fdatawrite mm,btrfs: add a filemap_flush_nr helper btrfs: push struct writeback_control into start_delalloc_inodes btrfs: use the local tmp_inode variable in start_delalloc_inodes ocfs2: don't opencode filemap_fdatawrite_range in ocfs2_journal_submit_inode_data_buffers 9p: don't opencode filemap_fdatawrite_range in v9fs_mmap_vm_close mm: don't opencode filemap_fdatawrite_range in filemap_invalidate_inode writeback: Add logging for slow writeback (exceeds sysctl_hung_task_timeout_secs) writeback: Wake up waiting tasks when finishing the writeback of a chunk.

fs: push list presence check into inode_io_list_del()

2025-11-25T09:34:49Z

For consistency with sb routines. ext4 is the only consumer outside of evict(). Damage-controlling it is outside of the scope of this cleanup. Signed-off-by: Mateusz Guzik Link: https://patch.msgid.link/20251103230911.516866-1-mjguzik@gmail.com Reviewed-by: Jan Kara Signed-off-by: Christian Brauner

fs: cosmetic fixes to lru handling

2025-11-25T09:34:49Z

1. inode_bit_waitqueue() was somehow placed between __inode_add_lru() and inode_add_lru(). move it up 2. assert ->i_lock is held in __inode_add_lru instead of just claiming it is needed 3. s/__inode_add_lru/__inode_lru_list_add/ for consistency with itself (inode_lru_list_del()) and similar routines for sb and io list management 4. push list presence check into inode_lru_list_del(), just like sb and io list Signed-off-by: Mateusz Guzik Link: https://patch.msgid.link/20251029131428.654761-2-mjguzik@gmail.com Reviewed-by: Jan Kara Signed-off-by: Christian Brauner

writeback: allow the file system to override MIN_WRITEBACK_PAGES

2025-10-29T14:54:31Z

The relatively low minimal writeback size of 4MiB means that written back inodes on rotational media are switched a lot. Besides introducing additional seeks, this also can lead to extreme file fragmentation on zoned devices when a lot of files are cached relative to the available writeback bandwidth. Add a superblock field that allows the file system to override the default size. Signed-off-by: Christoph Hellwig Link: https://patch.msgid.link/20251017034611.651385-3-hch@lst.de Reviewed-by: Jan Kara Reviewed-by: Darrick J. Wong Signed-off-by: Christian Brauner

writeback: cleanup writeback_chunk_size

2025-10-29T14:54:31Z

Return the pages directly when calculated instead of first assigning them back to a variable, and directly return for the data integrity / tagged case instead of going through an else clause. Signed-off-by: Christoph Hellwig Link: https://patch.msgid.link/20251017034611.651385-2-hch@lst.de Reviewed-by: Damien Le Moal Reviewed-by: Darrick J. Wong Reviewed-by: Nirjhar Roy (IBM) Reviewed-by: Jan Kara Signed-off-by: Christian Brauner

mm: remove filemap_fdatawrite_wbc

2025-10-29T14:50:41Z

Replace filemap_fdatawrite_wbc, which exposes a writeback_control to the callers with a filemap_writeback helper that takes all the possible arguments and declares the writeback_control itself. Signed-off-by: Christoph Hellwig Link: https://patch.msgid.link/20251024080431.324236-9-hch@lst.de Reviewed-by: David Hildenbrand Reviewed-by: Jan Kara Reviewed-by: Damien Le Moal Reviewed-by: Johannes Thumshirn Signed-off-by: Christian Brauner