The patch titled Subject: fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes() has been added to the -mm mm-hotfixes-unstable branch. Its filename is fs-writeback-skip-as_no_data_integrity-mappings-in-wait_sb_inodes.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Joanne Koong joannelkoong@gmail.com Subject: fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes() Date: Sun, 14 Dec 2025 19:00:43 -0800

Skip waiting on writeback for inodes that belong to mappings that do not have data integrity guarantees (denoted by the AS_NO_DATA_INTEGRITY mapping flag).

This restores fuse back to prior behavior where syncs are no-ops. This is needed because otherwise, if a system is running a faulty fuse server that does not reply to issued write requests, this will cause wait_sb_inodes() to wait forever.

Link: https://lkml.kernel.org/r/20251215030043.1431306-2-joannelkoong@gmail.com Fixes: 0c58a97f919c ("fuse: remove tmp folio for writebacks and internal rb tree") Signed-off-by: Joanne Koong joannelkoong@gmail.com Reported-by: Athul Krishna athul.krishna.kr@protonmail.com Reported-by: J. Neusch��fer j.neuschaefer@gmx.net Cc: Bonaccorso Salvatore carnil@debian.org Cc: Jonathan Neuschaefer j.neuschaefer@gmx.net Cc: Miklos Szeredi miklos@szeredi.hu Cc: Alexander Viro viro@zeniv.linux.org.uk Cc: Christian Brauner brauner@kernel.org Cc: Jan Kara jack@suse.cz Cc: "Matthew Wilcox (Oracle)" willy@infradead.org Cc: David Hildenbrand david@kernel.org Cc: Lorenzo Stoakes lorenzo.stoakes@oracle.com Cc: "Liam R. Howlett" Liam.Howlett@oracle.com Cc: Vlastimil Babka vbabka@suse.cz Cc: Mike Rapoport rppt@kernel.org Cc: Suren Baghdasaryan surenb@google.com Cc: Michal Hocko mhocko@suse.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

fs/fs-writeback.c | 3 ++- fs/fuse/file.c | 4 +++- include/linux/pagemap.h | 11 +++++++++++ 3 files changed, 16 insertions(+), 2 deletions(-)

--- a/fs/fs-writeback.c~fs-writeback-skip-as_no_data_integrity-mappings-in-wait_sb_inodes +++ a/fs/fs-writeback.c @@ -2751,7 +2751,8 @@ static void wait_sb_inodes(struct super_ * do not have the mapping lock. Skip it here, wb completion * will remove it. */ - if (!mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK)) + if (!mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK) || + mapping_no_data_integrity(mapping)) continue;

spin_unlock_irq(&sb->s_inode_wblist_lock); --- a/fs/fuse/file.c~fs-writeback-skip-as_no_data_integrity-mappings-in-wait_sb_inodes +++ a/fs/fuse/file.c @@ -3200,8 +3200,10 @@ void fuse_init_file_inode(struct inode *

inode->i_fop = &fuse_file_operations; inode->i_data.a_ops = &fuse_file_aops; - if (fc->writeback_cache) + if (fc->writeback_cache) { mapping_set_writeback_may_deadlock_on_reclaim(&inode->i_data); + mapping_set_no_data_integrity(&inode->i_data); + }

INIT_LIST_HEAD(&fi->write_files); INIT_LIST_HEAD(&fi->queued_writes); --- a/include/linux/pagemap.h~fs-writeback-skip-as_no_data_integrity-mappings-in-wait_sb_inodes +++ a/include/linux/pagemap.h @@ -210,6 +210,7 @@ enum mapping_flags { AS_WRITEBACK_MAY_DEADLOCK_ON_RECLAIM = 9, AS_KERNEL_FILE = 10, /* mapping for a fake kernel file that shouldn't account usage to user cgroups */ + AS_NO_DATA_INTEGRITY = 11, /* no data integrity guarantees */ /* Bits 16-25 are used for FOLIO_ORDER */ AS_FOLIO_ORDER_BITS = 5, AS_FOLIO_ORDER_MIN = 16, @@ -345,6 +346,16 @@ static inline bool mapping_writeback_may return test_bit(AS_WRITEBACK_MAY_DEADLOCK_ON_RECLAIM, &mapping->flags); }

+static inline void mapping_set_no_data_integrity(struct address_space *mapping) +{ + set_bit(AS_NO_DATA_INTEGRITY, &mapping->flags); +} + +static inline bool mapping_no_data_integrity(const struct address_space *mapping) +{ + return test_bit(AS_NO_DATA_INTEGRITY, &mapping->flags); +} + static inline gfp_t mapping_gfp_mask(const struct address_space *mapping) { return mapping->gfp_mask; _

Patches currently in -mm which might be from joannelkoong@gmail.com are

fs-writeback-skip-as_no_data_integrity-mappings-in-wait_sb_inodes.patch