* [PATCH v2 0/1] fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes() @ 2025-12-15 3:00 Joanne Koong 2025-12-15 3:00 ` [PATCH v2 1/1] " Joanne Koong 0 siblings, 1 reply; 5+ messages in thread From: Joanne Koong @ 2025-12-15 3:00 UTC (permalink / raw) To: akpm Cc: david, miklos, linux-mm, athul.krishna.kr, j.neuschaefer, carnil, linux-fsdevel, stable This patch reverts fuse back to its original behavior of sync being a no-op. This fixes the userspace regression reported by Athul and J. upstream in [1][2] where if there is a bug in a fuse server that causes the server to never complete writeback, it will make wait_sb_inodes() wait forever. Thanks, Joanne [1] https://lore.kernel.org/regressions/CAJnrk1ZjQ8W8NzojsvJPRXiv9TuYPNdj8Ye7=Cgkj=iV_i8EaA@mail.gmail.com/T/#t [2] https://lore.kernel.org/linux-fsdevel/aT7JRqhUvZvfUQlV@eldamar.lan/ Changelog: v1: https://lore.kernel.org/linux-mm/20251120184211.2379439-1-joannelkoong@gmail.com/ * Change AS_WRITEBACK_MAY_HANG to AS_NO_DATA_INTEGRITY and keep AS_WRITEBACK_MAY_DEADLOCK_ON_RECLAIM as is. Joanne Koong (1): fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes() fs/fs-writeback.c | 3 ++- fs/fuse/file.c | 4 +++- include/linux/pagemap.h | 11 +++++++++++ 3 files changed, 16 insertions(+), 2 deletions(-) -- 2.47.3 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH v2 1/1] fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes() 2025-12-15 3:00 [PATCH v2 0/1] fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes() Joanne Koong @ 2025-12-15 3:00 ` Joanne Koong 2025-12-15 17:09 ` Bernd Schubert 2025-12-16 18:13 ` J. Neuschäfer 0 siblings, 2 replies; 5+ messages in thread From: Joanne Koong @ 2025-12-15 3:00 UTC (permalink / raw) To: akpm Cc: david, miklos, linux-mm, athul.krishna.kr, j.neuschaefer, carnil, linux-fsdevel, stable 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. Fixes: 0c58a97f919c ("fuse: remove tmp folio for writebacks and internal rb tree") Reported-by: Athul Krishna <athul.krishna.kr@protonmail.com> Reported-by: J. Neuschäfer <j.neuschaefer@gmx.net> Cc: stable@vger.kernel.org Signed-off-by: Joanne Koong <joannelkoong@gmail.com> --- fs/fs-writeback.c | 3 ++- fs/fuse/file.c | 4 +++- include/linux/pagemap.h | 11 +++++++++++ 3 files changed, 16 insertions(+), 2 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 6800886c4d10..ab2e279ed3c2 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -2751,7 +2751,8 @@ static void wait_sb_inodes(struct super_block *sb) * 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); diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 01bc894e9c2b..3b2a171e652f 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -3200,8 +3200,10 @@ void fuse_init_file_inode(struct inode *inode, unsigned int flags) 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); diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 31a848485ad9..ec442af3f886 100644 --- a/include/linux/pagemap.h +++ b/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_deadlock_on_reclaim(const struct addres 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; -- 2.47.3 ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2 1/1] fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes() 2025-12-15 3:00 ` [PATCH v2 1/1] " Joanne Koong @ 2025-12-15 17:09 ` Bernd Schubert 2025-12-16 7:07 ` Joanne Koong 2025-12-16 18:13 ` J. Neuschäfer 1 sibling, 1 reply; 5+ messages in thread From: Bernd Schubert @ 2025-12-15 17:09 UTC (permalink / raw) To: Joanne Koong, akpm Cc: david, miklos, linux-mm, athul.krishna.kr, j.neuschaefer, carnil, linux-fsdevel, stable On 12/15/25 04:00, Joanne Koong wrote: > 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. > > Fixes: 0c58a97f919c ("fuse: remove tmp folio for writebacks and internal rb tree") > Reported-by: Athul Krishna <athul.krishna.kr@protonmail.com> > Reported-by: J. Neuschäfer <j.neuschaefer@gmx.net> > Cc: stable@vger.kernel.org > Signed-off-by: Joanne Koong <joannelkoong@gmail.com> > --- > fs/fs-writeback.c | 3 ++- > fs/fuse/file.c | 4 +++- > include/linux/pagemap.h | 11 +++++++++++ > 3 files changed, 16 insertions(+), 2 deletions(-) > > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c > index 6800886c4d10..ab2e279ed3c2 100644 > --- a/fs/fs-writeback.c > +++ b/fs/fs-writeback.c > @@ -2751,7 +2751,8 @@ static void wait_sb_inodes(struct super_block *sb) > * 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); > diff --git a/fs/fuse/file.c b/fs/fuse/file.c > index 01bc894e9c2b..3b2a171e652f 100644 > --- a/fs/fuse/file.c > +++ b/fs/fuse/file.c > @@ -3200,8 +3200,10 @@ void fuse_init_file_inode(struct inode *inode, unsigned int flags) > > 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); > + } For a future commit, maybe we could add a FUSE_INIT flag that allows privileged fuse server to not set this? Maybe even in combination with an enforced request timeout? > > INIT_LIST_HEAD(&fi->write_files); > INIT_LIST_HEAD(&fi->queued_writes); > diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h > index 31a848485ad9..ec442af3f886 100644 > --- a/include/linux/pagemap.h > +++ b/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_deadlock_on_reclaim(const struct addres > 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; Reviewed-by: Bernd Schubert <bschubert@ddn.com> ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2 1/1] fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes() 2025-12-15 17:09 ` Bernd Schubert @ 2025-12-16 7:07 ` Joanne Koong 0 siblings, 0 replies; 5+ messages in thread From: Joanne Koong @ 2025-12-16 7:07 UTC (permalink / raw) To: Bernd Schubert Cc: akpm, david, miklos, linux-mm, athul.krishna.kr, j.neuschaefer, carnil, linux-fsdevel, stable On Tue, Dec 16, 2025 at 1:09 AM Bernd Schubert <bernd@bsbernd.com> wrote: > > On 12/15/25 04:00, Joanne Koong wrote: > > 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. > > > > Fixes: 0c58a97f919c ("fuse: remove tmp folio for writebacks and internal rb tree") > > Reported-by: Athul Krishna <athul.krishna.kr@protonmail.com> > > Reported-by: J. Neuschäfer <j.neuschaefer@gmx.net> > > Cc: stable@vger.kernel.org > > Signed-off-by: Joanne Koong <joannelkoong@gmail.com> > > --- > > fs/fs-writeback.c | 3 ++- > > fs/fuse/file.c | 4 +++- > > include/linux/pagemap.h | 11 +++++++++++ > > 3 files changed, 16 insertions(+), 2 deletions(-) > > > > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c > > index 6800886c4d10..ab2e279ed3c2 100644 > > --- a/fs/fs-writeback.c > > +++ b/fs/fs-writeback.c > > @@ -2751,7 +2751,8 @@ static void wait_sb_inodes(struct super_block *sb) > > * 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); > > diff --git a/fs/fuse/file.c b/fs/fuse/file.c > > index 01bc894e9c2b..3b2a171e652f 100644 > > --- a/fs/fuse/file.c > > +++ b/fs/fuse/file.c > > @@ -3200,8 +3200,10 @@ void fuse_init_file_inode(struct inode *inode, unsigned int flags) > > > > 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); > > + } > > For a future commit, maybe we could add a FUSE_INIT flag that allows privileged > fuse server to not set this? Maybe even in combination with an enforced request > timeout? That sounds good, thanks for reviewing this, Bernd! > > > > > INIT_LIST_HEAD(&fi->write_files); > > INIT_LIST_HEAD(&fi->queued_writes); > > diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h > > index 31a848485ad9..ec442af3f886 100644 > > --- a/include/linux/pagemap.h > > +++ b/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_deadlock_on_reclaim(const struct addres > > 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; > > > Reviewed-by: Bernd Schubert <bschubert@ddn.com> ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2 1/1] fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes() 2025-12-15 3:00 ` [PATCH v2 1/1] " Joanne Koong 2025-12-15 17:09 ` Bernd Schubert @ 2025-12-16 18:13 ` J. Neuschäfer 1 sibling, 0 replies; 5+ messages in thread From: J. Neuschäfer @ 2025-12-16 18:13 UTC (permalink / raw) To: Joanne Koong Cc: akpm, david, miklos, linux-mm, athul.krishna.kr, j.neuschaefer, carnil, linux-fsdevel, stable On Sun, Dec 14, 2025 at 07:00:43PM -0800, Joanne Koong wrote: > 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. > > Fixes: 0c58a97f919c ("fuse: remove tmp folio for writebacks and internal rb tree") > Reported-by: Athul Krishna <athul.krishna.kr@protonmail.com> > Reported-by: J. Neuschäfer <j.neuschaefer@gmx.net> > Cc: stable@vger.kernel.org > Signed-off-by: Joanne Koong <joannelkoong@gmail.com> I can confirm that this patch fixes the issue I reported. (Tested by applying it on top of v6.19-rc1) Tested-by: J. Neuschäfer <j.neuschaefer@gmx.net> Thank you very much! > --- > fs/fs-writeback.c | 3 ++- > fs/fuse/file.c | 4 +++- > include/linux/pagemap.h | 11 +++++++++++ > 3 files changed, 16 insertions(+), 2 deletions(-) > > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c > index 6800886c4d10..ab2e279ed3c2 100644 > --- a/fs/fs-writeback.c > +++ b/fs/fs-writeback.c > @@ -2751,7 +2751,8 @@ static void wait_sb_inodes(struct super_block *sb) > * 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); > diff --git a/fs/fuse/file.c b/fs/fuse/file.c > index 01bc894e9c2b..3b2a171e652f 100644 > --- a/fs/fuse/file.c > +++ b/fs/fuse/file.c > @@ -3200,8 +3200,10 @@ void fuse_init_file_inode(struct inode *inode, unsigned int flags) > > 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); > diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h > index 31a848485ad9..ec442af3f886 100644 > --- a/include/linux/pagemap.h > +++ b/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_deadlock_on_reclaim(const struct addres > 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; > -- > 2.47.3 > ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2025-12-16 18:14 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2025-12-15 3:00 [PATCH v2 0/1] fs/writeback: skip AS_NO_DATA_INTEGRITY mappings in wait_sb_inodes() Joanne Koong 2025-12-15 3:00 ` [PATCH v2 1/1] " Joanne Koong 2025-12-15 17:09 ` Bernd Schubert 2025-12-16 7:07 ` Joanne Koong 2025-12-16 18:13 ` J. Neuschäfer
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