| Message ID | 20240131230827.207552-6-bschubert@ddn.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | fuse: inode IO modes and mmap | expand |
On Thu, 1 Feb 2024 at 00:09, Bernd Schubert <bschubert@ddn.com> wrote: > > From: Amir Goldstein <amir73il@gmail.com> > > The fuse inode io mode is determined by the mode of its open files/mmaps > and parallel dio. > > - caching io mode - files open in caching mode or mmap on direct_io file > - direct io mode - no files open in caching mode and no files mmaped > - parallel dio mode - direct io mode with parallel dio in progress Specifically if iocachectr is: > 0 -> caching io == 0 -> direct io < 0 -> parallel io > > We use a new FOPEN_CACHE_IO flag to explicitly mark a file that was open > in caching mode. This is really confusing. FOPEN_CACHE_IO is apparently an internally used flag, but it's defined on the userspace API. a) what is the meaning of this flag on the external API? b) what is the purpose of this flag internally? > > direct_io mmap uses page cache, so first mmap will mark the file as > FOPEN_DIRECT_IO|FOPEN_CACHE_IO (i.e. mixed mode) and inode will enter > the caching io mode. > > If the server opens the file with flags FOPEN_DIRECT_IO|FOPEN_CACHE_IO, > the inode enters caching io mode already on open. > > This allows executing parallel dio when inode is not in caching mode > even if shared mmap is allowed, but no mmaps have been performed on > the inode in question. > > An open in caching mode and mmap on direct_io file now waits for all > in-progress parallel dio writes to complete, so paralle dio writes > together with FUSE_DIRECT_IO_ALLOW_MMAP is enabled by this commit. I think the per file state is wrong, the above can be done with just the per-inode state. > > Signed-off-by: Bernd Schubert <bschubert@ddn.com> > Signed-off-by: Amir Goldstein <amir73il@gmail.com> > --- > fs/fuse/file.c | 215 ++++++++++++++++++++++++++++++++++++-- > fs/fuse/fuse_i.h | 79 +++++++++++++- > include/uapi/linux/fuse.h | 2 + > 3 files changed, 286 insertions(+), 10 deletions(-) > > diff --git a/fs/fuse/file.c b/fs/fuse/file.c > index 7d2f4b0eb36a..eb9929ff9f60 100644 > --- a/fs/fuse/file.c > +++ b/fs/fuse/file.c > @@ -105,10 +105,177 @@ static void fuse_release_end(struct fuse_mount *fm, struct fuse_args *args, > kfree(ra); > } > > +static bool fuse_file_is_direct_io(struct file *file) > +{ > + struct fuse_file *ff = file->private_data; > + > + return ff->open_flags & FOPEN_DIRECT_IO || file->f_flags & O_DIRECT; > +} This is one of the issues with the per-file state. O_DIRECT can be changed with fcntl(fd, F_SETFL, ...), so state calculated at open can go stale. > + > +/* > + * Wait for cached io to be allowed - > + * Blocks new parallel dio writes and waits for the in-progress parallel dio > + * writes to complete. > + */ > +static int fuse_inode_wait_for_cached_io(struct fuse_inode *fi) > +{ > + int err = 0; > + > + assert_spin_locked(&fi->lock); > + > + while (!err && !fuse_inode_get_io_cache(fi)) { > + /* > + * Setting the bit advises new direct-io writes > + * to use an exclusive lock - without it the wait below > + * might be forever. > + */ > + set_bit(FUSE_I_CACHE_IO_MODE, &fi->state); > + spin_unlock(&fi->lock); > + err = wait_event_killable(fi->direct_io_waitq, > + fuse_is_io_cache_allowed(fi)); > + spin_lock(&fi->lock); > + } > + /* Clear FUSE_I_CACHE_IO_MODE flag if failed to enter caching mode */ > + if (err && fi->iocachectr <= 0) > + clear_bit(FUSE_I_CACHE_IO_MODE, &fi->state); > + > + return err; > +} I suggest moving all infrastructure, including the inline helpers in fuse_i.h into a separate source file. > + > +/* Start cached io mode where parallel dio writes are not allowed */ > +static int fuse_file_cached_io_start(struct inode *inode) > +{ > + struct fuse_inode *fi = get_fuse_inode(inode); > + int err; > + > + spin_lock(&fi->lock); > + err = fuse_inode_wait_for_cached_io(fi); > + spin_unlock(&fi->lock); > + return err; > +} > + > +static void fuse_file_cached_io_end(struct inode *inode) > +{ > + struct fuse_inode *fi = get_fuse_inode(inode); > + > + spin_lock(&fi->lock); > + fuse_inode_put_io_cache(get_fuse_inode(inode)); > + spin_unlock(&fi->lock); > +} > + > +/* Start strictly uncached io mode where cache access is not allowed */ > +static int fuse_file_uncached_io_start(struct inode *inode) > +{ > + struct fuse_inode *fi = get_fuse_inode(inode); > + bool ok; > + > + spin_lock(&fi->lock); > + ok = fuse_inode_deny_io_cache(fi); > + spin_unlock(&fi->lock); > + return ok ? 0 : -ETXTBSY; > +} > + > +static void fuse_file_uncached_io_end(struct inode *inode) > +{ > + struct fuse_inode *fi = get_fuse_inode(inode); > + bool allow_cached_io; > + > + spin_lock(&fi->lock); > + allow_cached_io = fuse_inode_allow_io_cache(fi); > + spin_unlock(&fi->lock); > + if (allow_cached_io) > + wake_up(&fi->direct_io_waitq); > +} > + > +/* Open flags to determine regular file io mode */ > +#define FOPEN_IO_MODE_MASK \ > + (FOPEN_DIRECT_IO | FOPEN_CACHE_IO) > + > +/* Request access to submit new io to inode via open file */ > +static int fuse_file_io_open(struct file *file, struct inode *inode) > +{ > + struct fuse_file *ff = file->private_data; > + int iomode_flags = ff->open_flags & FOPEN_IO_MODE_MASK; > + int err; > + > + err = -EBUSY; > + if (WARN_ON(ff->io_opened)) > + goto fail; > + > + if (!S_ISREG(inode->i_mode) || FUSE_IS_DAX(inode)) { This S_ISREG check can also go away with separating the directory opens.
On Thu, Feb 1, 2024 at 4:47 PM Miklos Szeredi <miklos@szeredi.hu> wrote: > > On Thu, 1 Feb 2024 at 00:09, Bernd Schubert <bschubert@ddn.com> wrote: > > > > From: Amir Goldstein <amir73il@gmail.com> > > > > The fuse inode io mode is determined by the mode of its open files/mmaps > > and parallel dio. > > > > - caching io mode - files open in caching mode or mmap on direct_io file > > - direct io mode - no files open in caching mode and no files mmaped > > - parallel dio mode - direct io mode with parallel dio in progress > > Specifically if iocachectr is: > > > 0 -> caching io > == 0 -> direct io > < 0 -> parallel io > > > > > We use a new FOPEN_CACHE_IO flag to explicitly mark a file that was open > > in caching mode. > > This is really confusing. FOPEN_CACHE_IO is apparently an internally > used flag, but it's defined on the userspace API. > > a) what is the meaning of this flag on the external API? > b) what is the purpose of this flag internally? The purpose is to annotate the state of direct io file that was mmaped as FOPEN_DIRECT_IO | FOPEN_CACHE_IO. An fd like this puts inode in caching mode and its release may get inode out of caching mode. I did not manage to do refcoutning with fuse_vma_close(), because those calls are not balances with fuse_file_mmap() calls. The first mmap() of an FOPEN_DIRECT_IO file may incur wait for completion of parallel dio. The only use of exporting FOPEN_CACHE_IO to the server is that it could force incurring this wait at open() time instead of mmap() time. I also considered for servers that advertise FUSE_PASSTHROUGH capability to not allow open without specifying an explicit io mode, that is one of FOPEN_DIRECT_IO | FOPEN_CACHE_IO | FOPEN_PASSTHROUGH, but I did not actually implement those semantics ATM. > > > > > direct_io mmap uses page cache, so first mmap will mark the file as > > FOPEN_DIRECT_IO|FOPEN_CACHE_IO (i.e. mixed mode) and inode will enter > > the caching io mode. > > > > If the server opens the file with flags FOPEN_DIRECT_IO|FOPEN_CACHE_IO, > > the inode enters caching io mode already on open. > > > > This allows executing parallel dio when inode is not in caching mode > > even if shared mmap is allowed, but no mmaps have been performed on > > the inode in question. > > > > An open in caching mode and mmap on direct_io file now waits for all > > in-progress parallel dio writes to complete, so paralle dio writes > > together with FUSE_DIRECT_IO_ALLOW_MMAP is enabled by this commit. > > I think the per file state is wrong, the above can be done with just > the per-inode state. > The per-file state is to taint the file is "has been mmaped". I did not find another way of doing this. Please suggest another way. > > > > > Signed-off-by: Bernd Schubert <bschubert@ddn.com> > > Signed-off-by: Amir Goldstein <amir73il@gmail.com> > > --- > > fs/fuse/file.c | 215 ++++++++++++++++++++++++++++++++++++-- > > fs/fuse/fuse_i.h | 79 +++++++++++++- > > include/uapi/linux/fuse.h | 2 + > > 3 files changed, 286 insertions(+), 10 deletions(-) > > > > diff --git a/fs/fuse/file.c b/fs/fuse/file.c > > index 7d2f4b0eb36a..eb9929ff9f60 100644 > > --- a/fs/fuse/file.c > > +++ b/fs/fuse/file.c > > @@ -105,10 +105,177 @@ static void fuse_release_end(struct fuse_mount *fm, struct fuse_args *args, > > kfree(ra); > > } > > > > +static bool fuse_file_is_direct_io(struct file *file) > > +{ > > + struct fuse_file *ff = file->private_data; > > + > > + return ff->open_flags & FOPEN_DIRECT_IO || file->f_flags & O_DIRECT; > > +} > > This is one of the issues with the per-file state. O_DIRECT can be > changed with fcntl(fd, F_SETFL, ...), so state calculated at open can > go stale. > Ouch! Actually, it may not matter much if we just ignore O_DIRECT completely for the purpose of io modes. The io mode could be determined solely from FMODE_* flags. Worst case is that if the server opens an O_DIRECT file without FOPEN_DIRECT_IO, then this inode cannot do parallel dio and this inode cannot be opened in passthrough mode. I don't think that is such a big problem. Bernd, what do you think? BTW, server can and probably should open O_DIRECT files with FOPEN_PASSTHROUGH and that means something completely different than O_DIRECT && FOPEN_DIRECT_IO - it means that io is passed through to the backing file without doing buffered io on the backing file. > > + > > +/* > > + * Wait for cached io to be allowed - > > + * Blocks new parallel dio writes and waits for the in-progress parallel dio > > + * writes to complete. > > + */ > > +static int fuse_inode_wait_for_cached_io(struct fuse_inode *fi) > > +{ > > + int err = 0; > > + > > + assert_spin_locked(&fi->lock); > > + > > + while (!err && !fuse_inode_get_io_cache(fi)) { > > + /* > > + * Setting the bit advises new direct-io writes > > + * to use an exclusive lock - without it the wait below > > + * might be forever. > > + */ > > + set_bit(FUSE_I_CACHE_IO_MODE, &fi->state); > > + spin_unlock(&fi->lock); > > + err = wait_event_killable(fi->direct_io_waitq, > > + fuse_is_io_cache_allowed(fi)); > > + spin_lock(&fi->lock); > > + } > > + /* Clear FUSE_I_CACHE_IO_MODE flag if failed to enter caching mode */ > > + if (err && fi->iocachectr <= 0) > > + clear_bit(FUSE_I_CACHE_IO_MODE, &fi->state); > > + > > + return err; > > +} > > I suggest moving all infrastructure, including the inline helpers in > fuse_i.h into a separate source file. > OK. I can make those changes. > > + > > +/* Start cached io mode where parallel dio writes are not allowed */ > > +static int fuse_file_cached_io_start(struct inode *inode) > > +{ > > + struct fuse_inode *fi = get_fuse_inode(inode); > > + int err; > > + > > + spin_lock(&fi->lock); > > + err = fuse_inode_wait_for_cached_io(fi); > > + spin_unlock(&fi->lock); > > + return err; > > +} > > + > > +static void fuse_file_cached_io_end(struct inode *inode) > > +{ > > + struct fuse_inode *fi = get_fuse_inode(inode); > > + > > + spin_lock(&fi->lock); > > + fuse_inode_put_io_cache(get_fuse_inode(inode)); > > + spin_unlock(&fi->lock); > > +} > > + > > +/* Start strictly uncached io mode where cache access is not allowed */ > > +static int fuse_file_uncached_io_start(struct inode *inode) > > +{ > > + struct fuse_inode *fi = get_fuse_inode(inode); > > + bool ok; > > + > > + spin_lock(&fi->lock); > > + ok = fuse_inode_deny_io_cache(fi); > > + spin_unlock(&fi->lock); > > + return ok ? 0 : -ETXTBSY; > > +} > > + > > +static void fuse_file_uncached_io_end(struct inode *inode) > > +{ > > + struct fuse_inode *fi = get_fuse_inode(inode); > > + bool allow_cached_io; > > + > > + spin_lock(&fi->lock); > > + allow_cached_io = fuse_inode_allow_io_cache(fi); > > + spin_unlock(&fi->lock); > > + if (allow_cached_io) > > + wake_up(&fi->direct_io_waitq); > > +} > > + > > +/* Open flags to determine regular file io mode */ > > +#define FOPEN_IO_MODE_MASK \ > > + (FOPEN_DIRECT_IO | FOPEN_CACHE_IO) > > + > > +/* Request access to submit new io to inode via open file */ > > +static int fuse_file_io_open(struct file *file, struct inode *inode) > > +{ > > + struct fuse_file *ff = file->private_data; > > + int iomode_flags = ff->open_flags & FOPEN_IO_MODE_MASK; > > + int err; > > + > > + err = -EBUSY; > > + if (WARN_ON(ff->io_opened)) > > + goto fail; > > + > > + if (!S_ISREG(inode->i_mode) || FUSE_IS_DAX(inode)) { > > This S_ISREG check can also go away with separating the directory opens. OK. I will see if I can make that cleanup as well. Thanks, Amir.
On 2/1/24 17:33, Amir Goldstein wrote: > On Thu, Feb 1, 2024 at 4:47 PM Miklos Szeredi <miklos@szeredi.hu> wrote: >> >> On Thu, 1 Feb 2024 at 00:09, Bernd Schubert <bschubert@ddn.com> wrote: >>> >>> From: Amir Goldstein <amir73il@gmail.com> >>> >>> The fuse inode io mode is determined by the mode of its open files/mmaps >>> and parallel dio. >>> >>> - caching io mode - files open in caching mode or mmap on direct_io file >>> - direct io mode - no files open in caching mode and no files mmaped >>> - parallel dio mode - direct io mode with parallel dio in progress >> >> Specifically if iocachectr is: >> >>> 0 -> caching io >> == 0 -> direct io >> < 0 -> parallel io >> >>> >>> We use a new FOPEN_CACHE_IO flag to explicitly mark a file that was open >>> in caching mode. >> >> This is really confusing. FOPEN_CACHE_IO is apparently an internally >> used flag, but it's defined on the userspace API. >> >> a) what is the meaning of this flag on the external API? >> b) what is the purpose of this flag internally? > > The purpose is to annotate the state of direct io file that was mmaped > as FOPEN_DIRECT_IO | FOPEN_CACHE_IO. > An fd like this puts inode in caching mode and its release may get inode > out of caching mode. > > I did not manage to do refcoutning with fuse_vma_close(), because those > calls are not balances with fuse_file_mmap() calls. > > The first mmap() of an FOPEN_DIRECT_IO file may incur wait for completion > of parallel dio. > > The only use of exporting FOPEN_CACHE_IO to the server is that it could > force incurring this wait at open() time instead of mmap() time. > > I also considered for servers that advertise FUSE_PASSTHROUGH > capability to not allow open without specifying an explicit io mode, > that is one of FOPEN_DIRECT_IO | FOPEN_CACHE_IO | > FOPEN_PASSTHROUGH, but I did not actually implement those > semantics ATM. > >> >>> >>> direct_io mmap uses page cache, so first mmap will mark the file as >>> FOPEN_DIRECT_IO|FOPEN_CACHE_IO (i.e. mixed mode) and inode will enter >>> the caching io mode. >>> >>> If the server opens the file with flags FOPEN_DIRECT_IO|FOPEN_CACHE_IO, >>> the inode enters caching io mode already on open. >>> >>> This allows executing parallel dio when inode is not in caching mode >>> even if shared mmap is allowed, but no mmaps have been performed on >>> the inode in question. >>> >>> An open in caching mode and mmap on direct_io file now waits for all >>> in-progress parallel dio writes to complete, so paralle dio writes >>> together with FUSE_DIRECT_IO_ALLOW_MMAP is enabled by this commit. >> >> I think the per file state is wrong, the above can be done with just >> the per-inode state. >> > > The per-file state is to taint the file is "has been mmaped". > I did not find another way of doing this. > Please suggest another way. > >> >>> >>> Signed-off-by: Bernd Schubert <bschubert@ddn.com> >>> Signed-off-by: Amir Goldstein <amir73il@gmail.com> >>> --- >>> fs/fuse/file.c | 215 ++++++++++++++++++++++++++++++++++++-- >>> fs/fuse/fuse_i.h | 79 +++++++++++++- >>> include/uapi/linux/fuse.h | 2 + >>> 3 files changed, 286 insertions(+), 10 deletions(-) >>> >>> diff --git a/fs/fuse/file.c b/fs/fuse/file.c >>> index 7d2f4b0eb36a..eb9929ff9f60 100644 >>> --- a/fs/fuse/file.c >>> +++ b/fs/fuse/file.c >>> @@ -105,10 +105,177 @@ static void fuse_release_end(struct fuse_mount *fm, struct fuse_args *args, >>> kfree(ra); >>> } >>> >>> +static bool fuse_file_is_direct_io(struct file *file) >>> +{ >>> + struct fuse_file *ff = file->private_data; >>> + >>> + return ff->open_flags & FOPEN_DIRECT_IO || file->f_flags & O_DIRECT; >>> +} >> >> This is one of the issues with the per-file state. O_DIRECT can be >> changed with fcntl(fd, F_SETFL, ...), so state calculated at open can >> go stale. >> > > Ouch! > Actually, it may not matter much if we just ignore O_DIRECT > completely for the purpose of io modes. I had also missed that fcntl option :/ > > The io mode could be determined solely from FMODE_* flags. > > Worst case is that if the server opens an O_DIRECT file without > FOPEN_DIRECT_IO, then this inode cannot do parallel dio > and this inode cannot be opened in passthrough mode. > I don't think that is such a big problem. > > Bernd, what do you think? Yeah, currently FOPEN_PARALLEL_DIRECT_WRITES does not have an effect without FOPEN_DIRECT_IO. In my fuse-dio consolidation branch that changes. For me it is ok that parallel dio requires FOPEN_DIRECT_IO, easy enough to set on the server side in open methods when O_DIRECT is set. We should just document it in fuse.h. > > BTW, server can and probably should open O_DIRECT files > with FOPEN_PASSTHROUGH and that means something > completely different than O_DIRECT && FOPEN_DIRECT_IO - > it means that io is passed through to the backing file without > doing buffered io on the backing file. > >>> + >>> +/* >>> + * Wait for cached io to be allowed - >>> + * Blocks new parallel dio writes and waits for the in-progress parallel dio >>> + * writes to complete. >>> + */ >>> +static int fuse_inode_wait_for_cached_io(struct fuse_inode *fi) >>> +{ >>> + int err = 0; >>> + >>> + assert_spin_locked(&fi->lock); >>> + >>> + while (!err && !fuse_inode_get_io_cache(fi)) { >>> + /* >>> + * Setting the bit advises new direct-io writes >>> + * to use an exclusive lock - without it the wait below >>> + * might be forever. >>> + */ >>> + set_bit(FUSE_I_CACHE_IO_MODE, &fi->state); >>> + spin_unlock(&fi->lock); >>> + err = wait_event_killable(fi->direct_io_waitq, >>> + fuse_is_io_cache_allowed(fi)); >>> + spin_lock(&fi->lock); >>> + } >>> + /* Clear FUSE_I_CACHE_IO_MODE flag if failed to enter caching mode */ >>> + if (err && fi->iocachectr <= 0) >>> + clear_bit(FUSE_I_CACHE_IO_MODE, &fi->state); >>> + >>> + return err; >>> +} >> >> I suggest moving all infrastructure, including the inline helpers in >> fuse_i.h into a separate source file. >> > > OK. I can make those changes. > >>> + >>> +/* Start cached io mode where parallel dio writes are not allowed */ >>> +static int fuse_file_cached_io_start(struct inode *inode) >>> +{ >>> + struct fuse_inode *fi = get_fuse_inode(inode); >>> + int err; >>> + >>> + spin_lock(&fi->lock); >>> + err = fuse_inode_wait_for_cached_io(fi); >>> + spin_unlock(&fi->lock); >>> + return err; >>> +} >>> + >>> +static void fuse_file_cached_io_end(struct inode *inode) >>> +{ >>> + struct fuse_inode *fi = get_fuse_inode(inode); >>> + >>> + spin_lock(&fi->lock); >>> + fuse_inode_put_io_cache(get_fuse_inode(inode)); >>> + spin_unlock(&fi->lock); >>> +} >>> + >>> +/* Start strictly uncached io mode where cache access is not allowed */ >>> +static int fuse_file_uncached_io_start(struct inode *inode) >>> +{ >>> + struct fuse_inode *fi = get_fuse_inode(inode); >>> + bool ok; >>> + >>> + spin_lock(&fi->lock); >>> + ok = fuse_inode_deny_io_cache(fi); >>> + spin_unlock(&fi->lock); >>> + return ok ? 0 : -ETXTBSY; >>> +} >>> + >>> +static void fuse_file_uncached_io_end(struct inode *inode) >>> +{ >>> + struct fuse_inode *fi = get_fuse_inode(inode); >>> + bool allow_cached_io; >>> + >>> + spin_lock(&fi->lock); >>> + allow_cached_io = fuse_inode_allow_io_cache(fi); >>> + spin_unlock(&fi->lock); >>> + if (allow_cached_io) >>> + wake_up(&fi->direct_io_waitq); >>> +} >>> + >>> +/* Open flags to determine regular file io mode */ >>> +#define FOPEN_IO_MODE_MASK \ >>> + (FOPEN_DIRECT_IO | FOPEN_CACHE_IO) >>> + >>> +/* Request access to submit new io to inode via open file */ >>> +static int fuse_file_io_open(struct file *file, struct inode *inode) >>> +{ >>> + struct fuse_file *ff = file->private_data; >>> + int iomode_flags = ff->open_flags & FOPEN_IO_MODE_MASK; >>> + int err; >>> + >>> + err = -EBUSY; >>> + if (WARN_ON(ff->io_opened)) >>> + goto fail; >>> + >>> + if (!S_ISREG(inode->i_mode) || FUSE_IS_DAX(inode)) { >> >> This S_ISREG check can also go away with separating the directory opens. > > OK. I will see if I can make that cleanup as well. Note to myself, I need to make double sure that our (Dharmendras/mine) atomic open branch gets updated. Thanks, Bernd
On Thu, Feb 1, 2024 at 7:53 PM Bernd Schubert <bschubert@ddn.com> wrote: > > On 2/1/24 17:33, Amir Goldstein wrote: > > On Thu, Feb 1, 2024 at 4:47 PM Miklos Szeredi <miklos@szeredi.hu> wrote: > >> > >> On Thu, 1 Feb 2024 at 00:09, Bernd Schubert <bschubert@ddn.com> wrote: > >>> > >>> From: Amir Goldstein <amir73il@gmail.com> > >>> > >>> The fuse inode io mode is determined by the mode of its open files/mmaps > >>> and parallel dio. > >>> > >>> - caching io mode - files open in caching mode or mmap on direct_io file > >>> - direct io mode - no files open in caching mode and no files mmaped > >>> - parallel dio mode - direct io mode with parallel dio in progress > >> > >> Specifically if iocachectr is: > >> > >>> 0 -> caching io > >> == 0 -> direct io > >> < 0 -> parallel io > >> > >>> > >>> We use a new FOPEN_CACHE_IO flag to explicitly mark a file that was open > >>> in caching mode. > >> > >> This is really confusing. FOPEN_CACHE_IO is apparently an internally > >> used flag, but it's defined on the userspace API. > >> > >> a) what is the meaning of this flag on the external API? > >> b) what is the purpose of this flag internally? > > > > The purpose is to annotate the state of direct io file that was mmaped > > as FOPEN_DIRECT_IO | FOPEN_CACHE_IO. > > An fd like this puts inode in caching mode and its release may get inode > > out of caching mode. > > > > I did not manage to do refcoutning with fuse_vma_close(), because those > > calls are not balances with fuse_file_mmap() calls. > > > > The first mmap() of an FOPEN_DIRECT_IO file may incur wait for completion > > of parallel dio. > > > > The only use of exporting FOPEN_CACHE_IO to the server is that it could > > force incurring this wait at open() time instead of mmap() time. > > > > I also considered for servers that advertise FUSE_PASSTHROUGH > > capability to not allow open without specifying an explicit io mode, > > that is one of FOPEN_DIRECT_IO | FOPEN_CACHE_IO | > > FOPEN_PASSTHROUGH, but I did not actually implement those > > semantics ATM. > > > >> > >>> > >>> direct_io mmap uses page cache, so first mmap will mark the file as > >>> FOPEN_DIRECT_IO|FOPEN_CACHE_IO (i.e. mixed mode) and inode will enter > >>> the caching io mode. > >>> > >>> If the server opens the file with flags FOPEN_DIRECT_IO|FOPEN_CACHE_IO, > >>> the inode enters caching io mode already on open. > >>> > >>> This allows executing parallel dio when inode is not in caching mode > >>> even if shared mmap is allowed, but no mmaps have been performed on > >>> the inode in question. > >>> > >>> An open in caching mode and mmap on direct_io file now waits for all > >>> in-progress parallel dio writes to complete, so paralle dio writes > >>> together with FUSE_DIRECT_IO_ALLOW_MMAP is enabled by this commit. > >> > >> I think the per file state is wrong, the above can be done with just > >> the per-inode state. > >> > > > > The per-file state is to taint the file is "has been mmaped". > > I did not find another way of doing this. > > Please suggest another way. > > > >> > >>> > >>> Signed-off-by: Bernd Schubert <bschubert@ddn.com> > >>> Signed-off-by: Amir Goldstein <amir73il@gmail.com> > >>> --- > >>> fs/fuse/file.c | 215 ++++++++++++++++++++++++++++++++++++-- > >>> fs/fuse/fuse_i.h | 79 +++++++++++++- > >>> include/uapi/linux/fuse.h | 2 + > >>> 3 files changed, 286 insertions(+), 10 deletions(-) > >>> > >>> diff --git a/fs/fuse/file.c b/fs/fuse/file.c > >>> index 7d2f4b0eb36a..eb9929ff9f60 100644 > >>> --- a/fs/fuse/file.c > >>> +++ b/fs/fuse/file.c > >>> @@ -105,10 +105,177 @@ static void fuse_release_end(struct fuse_mount *fm, struct fuse_args *args, > >>> kfree(ra); > >>> } > >>> > >>> +static bool fuse_file_is_direct_io(struct file *file) > >>> +{ > >>> + struct fuse_file *ff = file->private_data; > >>> + > >>> + return ff->open_flags & FOPEN_DIRECT_IO || file->f_flags & O_DIRECT; > >>> +} > >> > >> This is one of the issues with the per-file state. O_DIRECT can be > >> changed with fcntl(fd, F_SETFL, ...), so state calculated at open can > >> go stale. > >> > > > > Ouch! > > Actually, it may not matter much if we just ignore O_DIRECT > > completely for the purpose of io modes. > > I had also missed that fcntl option :/ > > > > > The io mode could be determined solely from FMODE_* flags. > > > > Worst case is that if the server opens an O_DIRECT file without > > FOPEN_DIRECT_IO, then this inode cannot do parallel dio > > and this inode cannot be opened in passthrough mode. > > I don't think that is such a big problem. > > > > Bernd, what do you think? > > Yeah, currently FOPEN_PARALLEL_DIRECT_WRITES does not have an effect > without FOPEN_DIRECT_IO. In my fuse-dio consolidation branch that > changes. For me it is ok that parallel dio requires > FOPEN_DIRECT_IO, easy enough to set on the server side in open methods > when O_DIRECT is set. We should just document it in fuse.h. > Ok. I removed the O_DIRECT code from the last version I pushed. Please verify that it does not break anything in your dio tests. > > > > BTW, server can and probably should open O_DIRECT files > > with FOPEN_PASSTHROUGH and that means something > > completely different than O_DIRECT && FOPEN_DIRECT_IO - > > it means that io is passed through to the backing file without > > doing buffered io on the backing file. > > > >>> + > >>> +/* > >>> + * Wait for cached io to be allowed - > >>> + * Blocks new parallel dio writes and waits for the in-progress parallel dio > >>> + * writes to complete. > >>> + */ > >>> +static int fuse_inode_wait_for_cached_io(struct fuse_inode *fi) > >>> +{ > >>> + int err = 0; > >>> + > >>> + assert_spin_locked(&fi->lock); > >>> + > >>> + while (!err && !fuse_inode_get_io_cache(fi)) { > >>> + /* > >>> + * Setting the bit advises new direct-io writes > >>> + * to use an exclusive lock - without it the wait below > >>> + * might be forever. > >>> + */ > >>> + set_bit(FUSE_I_CACHE_IO_MODE, &fi->state); > >>> + spin_unlock(&fi->lock); > >>> + err = wait_event_killable(fi->direct_io_waitq, > >>> + fuse_is_io_cache_allowed(fi)); > >>> + spin_lock(&fi->lock); > >>> + } > >>> + /* Clear FUSE_I_CACHE_IO_MODE flag if failed to enter caching mode */ > >>> + if (err && fi->iocachectr <= 0) > >>> + clear_bit(FUSE_I_CACHE_IO_MODE, &fi->state); > >>> + > >>> + return err; > >>> +} > >> > >> I suggest moving all infrastructure, including the inline helpers in > >> fuse_i.h into a separate source file. > >> > > > > OK. I can make those changes. > > moved to iomode.c > >>> + > >>> +/* Start cached io mode where parallel dio writes are not allowed */ > >>> +static int fuse_file_cached_io_start(struct inode *inode) > >>> +{ > >>> + struct fuse_inode *fi = get_fuse_inode(inode); > >>> + int err; > >>> + > >>> + spin_lock(&fi->lock); > >>> + err = fuse_inode_wait_for_cached_io(fi); > >>> + spin_unlock(&fi->lock); > >>> + return err; > >>> +} > >>> + > >>> +static void fuse_file_cached_io_end(struct inode *inode) > >>> +{ > >>> + struct fuse_inode *fi = get_fuse_inode(inode); > >>> + > >>> + spin_lock(&fi->lock); > >>> + fuse_inode_put_io_cache(get_fuse_inode(inode)); > >>> + spin_unlock(&fi->lock); > >>> +} > >>> + > >>> +/* Start strictly uncached io mode where cache access is not allowed */ > >>> +static int fuse_file_uncached_io_start(struct inode *inode) > >>> +{ > >>> + struct fuse_inode *fi = get_fuse_inode(inode); > >>> + bool ok; > >>> + > >>> + spin_lock(&fi->lock); > >>> + ok = fuse_inode_deny_io_cache(fi); > >>> + spin_unlock(&fi->lock); > >>> + return ok ? 0 : -ETXTBSY; > >>> +} > >>> + > >>> +static void fuse_file_uncached_io_end(struct inode *inode) > >>> +{ > >>> + struct fuse_inode *fi = get_fuse_inode(inode); > >>> + bool allow_cached_io; > >>> + > >>> + spin_lock(&fi->lock); > >>> + allow_cached_io = fuse_inode_allow_io_cache(fi); > >>> + spin_unlock(&fi->lock); > >>> + if (allow_cached_io) > >>> + wake_up(&fi->direct_io_waitq); > >>> +} > >>> + > >>> +/* Open flags to determine regular file io mode */ > >>> +#define FOPEN_IO_MODE_MASK \ > >>> + (FOPEN_DIRECT_IO | FOPEN_CACHE_IO) > >>> + > >>> +/* Request access to submit new io to inode via open file */ > >>> +static int fuse_file_io_open(struct file *file, struct inode *inode) > >>> +{ > >>> + struct fuse_file *ff = file->private_data; > >>> + int iomode_flags = ff->open_flags & FOPEN_IO_MODE_MASK; > >>> + int err; > >>> + > >>> + err = -EBUSY; > >>> + if (WARN_ON(ff->io_opened)) > >>> + goto fail; > >>> + > >>> + if (!S_ISREG(inode->i_mode) || FUSE_IS_DAX(inode)) { > >> > >> This S_ISREG check can also go away with separating the directory opens. > > > > OK. I will see if I can make that cleanup as well. > done. Bernd, I pushed branch with latest cleanup patches and addressed Miklos' simpler review comments to: https://github.com/amir73il/linux/commits/fuse_io_mode-020224/ The one thing I did not change is the FOPEN_CACHE_IO flag and per-file state, because I have no idea how to fix this differently. I can change the external flag to an internal state if that is the main concern, but I had a feeling there was more to it. If you get the chance, please review and re-run your tests. Thanks, Amir.
On Thu, Feb 1, 2024 at 6:33 PM Amir Goldstein <amir73il@gmail.com> wrote: > > On Thu, Feb 1, 2024 at 4:47 PM Miklos Szeredi <miklos@szeredi.hu> wrote: > > > > On Thu, 1 Feb 2024 at 00:09, Bernd Schubert <bschubert@ddn.com> wrote: > > > > > > From: Amir Goldstein <amir73il@gmail.com> > > > > > > The fuse inode io mode is determined by the mode of its open files/mmaps > > > and parallel dio. > > > > > > - caching io mode - files open in caching mode or mmap on direct_io file > > > - direct io mode - no files open in caching mode and no files mmaped > > > - parallel dio mode - direct io mode with parallel dio in progress > > > > Specifically if iocachectr is: > > > > > 0 -> caching io > > == 0 -> direct io > > < 0 -> parallel io > > > > > > > > We use a new FOPEN_CACHE_IO flag to explicitly mark a file that was open > > > in caching mode. > > > > This is really confusing. FOPEN_CACHE_IO is apparently an internally > > used flag, but it's defined on the userspace API. > > > > a) what is the meaning of this flag on the external API? > > b) what is the purpose of this flag internally? > > The purpose is to annotate the state of direct io file that was mmaped > as FOPEN_DIRECT_IO | FOPEN_CACHE_IO. > An fd like this puts inode in caching mode and its release may get inode > out of caching mode. > > I did not manage to do refcoutning with fuse_vma_close(), because those > calls are not balances with fuse_file_mmap() calls. > > The first mmap() of an FOPEN_DIRECT_IO file may incur wait for completion > of parallel dio. > > The only use of exporting FOPEN_CACHE_IO to the server is that it could > force incurring this wait at open() time instead of mmap() time. > Miklos, I have played with this rebranding of FOPEN_CACHE_IO => FOPEN_NO_PARALLEL_DIO_WRITES The meaning of the rebranded flag is: Prevent parallel dio on inode for as long as this file is kept open. The io modes code sets this flag implicitly on the first shared mmap. Let me know if this makes the external flag easier to swallow. Of course I can make this flag internal and not and FOPEN_ flag at all, but IMO, the code is easier to understand when the type of iocachectl refcount held by any file is specified by its FOPEN_ flags. Let me know what you think. Thanks, Amir. https://github.com/amir73il/linux/commits/fuse_io_mode-wip/ --- a/include/uapi/linux/fuse.h +++ b/include/uapi/linux/fuse.h @@ -353,7 +353,7 @@ struct fuse_file_lock { * FOPEN_STREAM: the file is stream-like (no file position at all) * FOPEN_NOFLUSH: don't flush data cache on close (unless FUSE_WRITEBACK_CACHE) * FOPEN_PARALLEL_DIRECT_WRITES: Allow concurrent direct writes on the same inode - * FOPEN_CACHE_IO: using cache for this open file (incl. mmap on direct_io) + * FOPEN_NO_PARALLEL_DIO_WRITES: Deny concurrent direct writes on the same inode */ #define FOPEN_DIRECT_IO (1 << 0) #define FOPEN_KEEP_CACHE (1 << 1) @@ -362,7 +362,7 @@ struct fuse_file_lock { #define FOPEN_STREAM (1 << 4) #define FOPEN_NOFLUSH (1 << 5) #define FOPEN_PARALLEL_DIRECT_WRITES (1 << 6) -#define FOPEN_CACHE_IO (1 << 7) +#define FOPEN_NO_PARALLEL_DIO_WRITES (1 << 7) ... - /* Set explicit FOPEN_CACHE_IO flag for file open in caching mode */ - if (!fuse_file_is_direct_io(file)) - ff->open_flags |= FOPEN_CACHE_IO; + /* + * FOPEN_CACHE_IO is an internal flag that is set on file not open in + * direct io mode and it cannot be set explicitly by the server. + * FOPEN_NO_PARALLEL_DIO_WRITES is set on file open in caching mode and + * is not allowed together with FOPEN_PARALLEL_DIRECT_WRITES. + * This includes a file open with O_DIRECT, but server did not specify + * FOPEN_DIRECT_IO. In this case, a later fcntl() could remove O_DIRECT, + * so we put the inode in caching mode to prevent parallel dio. + * FOPEN_PARALLEL_DIRECT_WRITES requires FOPEN_DIRECT_IO. + */ + if (ff->open_flags & FOPEN_NO_PARALLEL_DIO_WRITES) { + if (ff->open_flags & FOPEN_PARALLEL_DIRECT_WRITES) + goto fail; + } else if (!(ff->open_flags & FOPEN_DIRECT_IO)) { + ff->open_flags |= FOPEN_NO_PARALLEL_DIO_WRITES; + ff->open_flags &= ~FOPEN_PARALLEL_DIRECT_WRITES; + }
On Tue, 6 Feb 2024 at 13:39, Amir Goldstein <amir73il@gmail.com> wrote: > I have played with this rebranding of > FOPEN_CACHE_IO => FOPEN_NO_PARALLEL_DIO_WRITES > > The meaning of the rebranded flag is: > Prevent parallel dio on inode for as long as this file is kept open. > > The io modes code sets this flag implicitly on the first shared mmap. > > Let me know if this makes the external flag easier to swallow. > Of course I can make this flag internal and not and FOPEN_ flag > at all, but IMO, the code is easier to understand when the type of > iocachectl refcount held by any file is specified by its FOPEN_ flags. If there's no clear use case that would benefit from having this flag on the userspace interface, then I'd recommend not to export it for now. I understand the need for clarifying the various states that the kernel can be, but I think that's a bigger project involving e.g. data and metadata cache validity, where the current rules are pretty convoluted. So for now I'd just stick with the implicit state change by mmap. BTW, I started looking at the fuse-backing-fd branch and really hope we can get this into shape for the next merge window. Thanks, Miklos
On Tue, Feb 6, 2024 at 2:53 PM Miklos Szeredi <miklos@szeredi.hu> wrote: > > On Tue, 6 Feb 2024 at 13:39, Amir Goldstein <amir73il@gmail.com> wrote: > > > I have played with this rebranding of > > FOPEN_CACHE_IO => FOPEN_NO_PARALLEL_DIO_WRITES > > > > The meaning of the rebranded flag is: > > Prevent parallel dio on inode for as long as this file is kept open. > > > > The io modes code sets this flag implicitly on the first shared mmap. > > > > Let me know if this makes the external flag easier to swallow. > > Of course I can make this flag internal and not and FOPEN_ flag > > at all, but IMO, the code is easier to understand when the type of > > iocachectl refcount held by any file is specified by its FOPEN_ flags. > > If there's no clear use case that would benefit from having this flag > on the userspace interface, then I'd recommend not to export it for > now. > > I understand the need for clarifying the various states that the > kernel can be, but I think that's a bigger project involving e.g. data > and metadata cache validity, where the current rules are pretty > convoluted. > > So for now I'd just stick with the implicit state change by mmap. > Understood. Do you object to reserving the flag in uapi, but disallowing the server to set it? This is how it is in my branch after addressing you other review comments: https://github.com/amir73il/linux/commits/fuse_io_mode-030224 * FOPEN_PARALLEL_DIRECT_WRITES: Allow concurrent direct writes on the same inode + * FOPEN_CACHE_IO: internal flag for mmap of direct_io (reserved for future use) */ > BTW, I started looking at the fuse-backing-fd branch and really hope > we can get this into shape for the next merge window. > As far as I am concerned, those patches are good to go. I was only waiting for fuse_io_mode to stabilize, in case you wanted bigger changes there. I will post the FUSE_PASSTHROUGH patches, based on fuse_io_mode OTM so you could review them on-list as well. Thanks, Amir.
diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 7d2f4b0eb36a..eb9929ff9f60 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -105,10 +105,177 @@ static void fuse_release_end(struct fuse_mount *fm, struct fuse_args *args, kfree(ra); } +static bool fuse_file_is_direct_io(struct file *file) +{ + struct fuse_file *ff = file->private_data; + + return ff->open_flags & FOPEN_DIRECT_IO || file->f_flags & O_DIRECT; +} + +/* + * Wait for cached io to be allowed - + * Blocks new parallel dio writes and waits for the in-progress parallel dio + * writes to complete. + */ +static int fuse_inode_wait_for_cached_io(struct fuse_inode *fi) +{ + int err = 0; + + assert_spin_locked(&fi->lock); + + while (!err && !fuse_inode_get_io_cache(fi)) { + /* + * Setting the bit advises new direct-io writes + * to use an exclusive lock - without it the wait below + * might be forever. + */ + set_bit(FUSE_I_CACHE_IO_MODE, &fi->state); + spin_unlock(&fi->lock); + err = wait_event_killable(fi->direct_io_waitq, + fuse_is_io_cache_allowed(fi)); + spin_lock(&fi->lock); + } + /* Clear FUSE_I_CACHE_IO_MODE flag if failed to enter caching mode */ + if (err && fi->iocachectr <= 0) + clear_bit(FUSE_I_CACHE_IO_MODE, &fi->state); + + return err; +} + +/* Start cached io mode where parallel dio writes are not allowed */ +static int fuse_file_cached_io_start(struct inode *inode) +{ + struct fuse_inode *fi = get_fuse_inode(inode); + int err; + + spin_lock(&fi->lock); + err = fuse_inode_wait_for_cached_io(fi); + spin_unlock(&fi->lock); + return err; +} + +static void fuse_file_cached_io_end(struct inode *inode) +{ + struct fuse_inode *fi = get_fuse_inode(inode); + + spin_lock(&fi->lock); + fuse_inode_put_io_cache(get_fuse_inode(inode)); + spin_unlock(&fi->lock); +} + +/* Start strictly uncached io mode where cache access is not allowed */ +static int fuse_file_uncached_io_start(struct inode *inode) +{ + struct fuse_inode *fi = get_fuse_inode(inode); + bool ok; + + spin_lock(&fi->lock); + ok = fuse_inode_deny_io_cache(fi); + spin_unlock(&fi->lock); + return ok ? 0 : -ETXTBSY; +} + +static void fuse_file_uncached_io_end(struct inode *inode) +{ + struct fuse_inode *fi = get_fuse_inode(inode); + bool allow_cached_io; + + spin_lock(&fi->lock); + allow_cached_io = fuse_inode_allow_io_cache(fi); + spin_unlock(&fi->lock); + if (allow_cached_io) + wake_up(&fi->direct_io_waitq); +} + +/* Open flags to determine regular file io mode */ +#define FOPEN_IO_MODE_MASK \ + (FOPEN_DIRECT_IO | FOPEN_CACHE_IO) + +/* Request access to submit new io to inode via open file */ +static int fuse_file_io_open(struct file *file, struct inode *inode) +{ + struct fuse_file *ff = file->private_data; + int iomode_flags = ff->open_flags & FOPEN_IO_MODE_MASK; + int err; + + err = -EBUSY; + if (WARN_ON(ff->io_opened)) + goto fail; + + if (!S_ISREG(inode->i_mode) || FUSE_IS_DAX(inode)) { + err = -EINVAL; + if (iomode_flags) + goto fail; + return 0; + } + + /* Set explicit FOPEN_CACHE_IO flag for file open in caching mode */ + if (!fuse_file_is_direct_io(file)) + ff->open_flags |= FOPEN_CACHE_IO; + + /* First caching file open enters caching inode io mode */ + if (ff->open_flags & FOPEN_CACHE_IO) { + err = fuse_file_cached_io_start(inode); + if (err) + goto fail; + } + + ff->io_opened = true; + return 0; + +fail: + pr_debug("failed to open file in requested io mode (open_flags=0x%x, err=%i).\n", + ff->open_flags, err); + /* + * The file open mode determines the inode io mode. + * Using incorrect open mode is a server mistake, which results in + * user visible failure of open() with EIO error. + */ + return -EIO; +} + +/* Request access to submit new io to inode via mmap */ +static int fuse_file_io_mmap(struct fuse_file *ff, struct inode *inode) +{ + struct fuse_inode *fi = get_fuse_inode(inode); + int err = 0; + + if (WARN_ON(!ff->io_opened)) + return -ENODEV; + + spin_lock(&fi->lock); + /* First mmap of direct_io file enters caching inode io mode */ + if (!(ff->open_flags & FOPEN_CACHE_IO)) { + err = fuse_inode_wait_for_cached_io(fi); + if (!err) + ff->open_flags |= FOPEN_CACHE_IO; + } + spin_unlock(&fi->lock); + + return err; +} + +/* No more pending io and no new io possible to inode via open/mmapped file */ +static void fuse_file_io_release(struct fuse_file *ff, struct inode *inode) +{ + if (!ff->io_opened) + return; + + /* Last caching file close exits caching inode io mode */ + if (ff->open_flags & FOPEN_CACHE_IO) + fuse_file_cached_io_end(inode); + + ff->io_opened = false; +} + static void fuse_file_put(struct fuse_file *ff, bool sync, bool isdir) { if (refcount_dec_and_test(&ff->count)) { struct fuse_args *args = &ff->release_args->args; + struct inode *inode = ff->release_args->inode; + + if (inode) + fuse_file_io_release(ff, inode); if (isdir ? ff->fm->fc->no_opendir : ff->fm->fc->no_open) { /* Do nothing when client does not implement 'open' */ @@ -161,7 +328,7 @@ struct fuse_file *fuse_file_open(struct fuse_mount *fm, u64 nodeid, } if (isdir) - ff->open_flags &= ~FOPEN_DIRECT_IO; + ff->open_flags &= ~(FOPEN_DIRECT_IO | FOPEN_CACHE_IO); ff->nodeid = nodeid; @@ -199,6 +366,11 @@ int fuse_finish_open(struct inode *inode, struct file *file) { struct fuse_file *ff = file->private_data; struct fuse_conn *fc = get_fuse_conn(inode); + int err; + + err = fuse_file_io_open(file, inode); + if (err) + return err; if (ff->open_flags & FOPEN_STREAM) stream_open(inode, file); @@ -1320,6 +1492,7 @@ static bool fuse_dio_wr_exclusive_lock(struct kiocb *iocb, struct iov_iter *from struct file *file = iocb->ki_filp; struct fuse_file *ff = file->private_data; struct inode *inode = file_inode(iocb->ki_filp); + struct fuse_inode *fi = get_fuse_inode(inode); /* server side has to advise that it supports parallel dio writes */ if (!(ff->open_flags & FOPEN_PARALLEL_DIRECT_WRITES)) @@ -1331,11 +1504,9 @@ static bool fuse_dio_wr_exclusive_lock(struct kiocb *iocb, struct iov_iter *from if (iocb->ki_flags & IOCB_APPEND) return true; - /* combination opf page access and direct-io difficult, shared - * locks actually introduce a conflict. - */ - if (get_fuse_conn(inode)->direct_io_allow_mmap) - return true; + /* shared locks are not allowed with parallel page cache IO */ + if (test_bit(FUSE_I_CACHE_IO_MODE, &fi->state)) + return false; /* parallel dio beyond eof is at least for now not supported */ if (fuse_io_past_eof(iocb, from)) @@ -1355,10 +1526,14 @@ static void fuse_dio_lock(struct kiocb *iocb, struct iov_iter *from, } else { inode_lock_shared(inode); /* - * Previous check was without inode lock and might have raced, - * check again. + * New parallal dio allowed only if inode is not in caching + * mode and denies new opens in caching mode. This check + * should be performed only after taking shared inode lock. + * Previous past eof check was without inode lock and might + * have raced, so check it again. */ - if (fuse_io_past_eof(iocb, from)) { + if (fuse_io_past_eof(iocb, from) || + fuse_file_uncached_io_start(inode) != 0) { inode_unlock_shared(inode); inode_lock(inode); *exclusive = true; @@ -1371,6 +1546,8 @@ static void fuse_dio_unlock(struct inode *inode, bool exclusive) if (exclusive) { inode_unlock(inode); } else { + /* Allow opens in caching mode after last parallel dio end */ + fuse_file_uncached_io_end(inode); inode_unlock_shared(inode); } } @@ -2500,11 +2677,16 @@ static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma) { struct fuse_file *ff = file->private_data; struct fuse_conn *fc = ff->fm->fc; + int rc; /* DAX mmap is superior to direct_io mmap */ if (FUSE_IS_DAX(file_inode(file))) return fuse_dax_mmap(file, vma); + /* + * FOPEN_DIRECT_IO handling is special compared to O_DIRECT, + * as does not allow MAP_SHARED mmap without FUSE_DIRECT_IO_ALLOW_MMAP. + */ if (ff->open_flags & FOPEN_DIRECT_IO) { /* * Can't provide the coherency needed for MAP_SHARED @@ -2515,10 +2697,23 @@ static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma) invalidate_inode_pages2(file->f_mapping); + /* + * First mmap of direct_io file enters caching inode io mode. + * Also waits for parallel dio writers to go into serial mode + * (exclusive instead of shared lock). + */ + rc = fuse_file_io_mmap(ff, file_inode(file)); + if (rc) + return rc; + if (!(vma->vm_flags & VM_MAYSHARE)) { /* MAP_PRIVATE */ return generic_file_mmap(file, vma); } + } else if (file->f_flags & O_DIRECT) { + rc = fuse_file_io_mmap(ff, file_inode(file)); + if (rc) + return rc; } if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) @@ -3287,7 +3482,9 @@ void fuse_init_file_inode(struct inode *inode, unsigned int flags) INIT_LIST_HEAD(&fi->write_files); INIT_LIST_HEAD(&fi->queued_writes); fi->writectr = 0; + fi->iocachectr = 0; init_waitqueue_head(&fi->page_waitq); + init_waitqueue_head(&fi->direct_io_waitq); fi->writepages = RB_ROOT; if (IS_ENABLED(CONFIG_FUSE_DAX)) diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 1c0cde4022f0..cb961f9a13c3 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -111,7 +111,7 @@ struct fuse_inode { u64 attr_version; union { - /* Write related fields (regular file only) */ + /* read/write io cache (regular file only) */ struct { /* Files usable in writepage. Protected by fi->lock */ struct list_head write_files; @@ -123,9 +123,15 @@ struct fuse_inode { * (FUSE_NOWRITE) means more writes are blocked */ int writectr; + /** Number of files/maps using page cache */ + int iocachectr; + /* Waitq for writepage completion */ wait_queue_head_t page_waitq; + /* waitq for direct-io completion */ + wait_queue_head_t direct_io_waitq; + /* List of writepage requestst (pending or sent) */ struct rb_root writepages; }; @@ -187,6 +193,8 @@ enum { FUSE_I_BAD, /* Has btime */ FUSE_I_BTIME, + /* Wants or already has page cache IO */ + FUSE_I_CACHE_IO_MODE, }; struct fuse_conn; @@ -246,6 +254,9 @@ struct fuse_file { /** Has flock been performed on this file? */ bool flock:1; + + /** Was file opened for io? */ + bool io_opened:1; }; /** One input argument of a request */ @@ -1349,6 +1360,72 @@ int fuse_fileattr_set(struct mnt_idmap *idmap, struct dentry *dentry, struct fileattr *fa); /* file.c */ +/* + * Request an open in caching mode. + * Return true if in caching mode. + */ +static inline bool fuse_inode_get_io_cache(struct fuse_inode *fi) +{ + assert_spin_locked(&fi->lock); + if (fi->iocachectr < 0) + return false; + fi->iocachectr++; + if (fi->iocachectr == 1) + set_bit(FUSE_I_CACHE_IO_MODE, &fi->state); + + return true; +} + +/* + * Release an open in caching mode. + * Return true if no more files open in caching mode. + */ +static inline bool fuse_inode_put_io_cache(struct fuse_inode *fi) +{ + assert_spin_locked(&fi->lock); + if (WARN_ON(fi->iocachectr <= 0)) + return false; + + if (--fi->iocachectr == 0) { + clear_bit(FUSE_I_CACHE_IO_MODE, &fi->state); + return true; + } + + return false; +} + +/* + * Requets to deny new opens in caching mode. + * Return true if denying new opens in caching mode. + */ +static inline bool fuse_inode_deny_io_cache(struct fuse_inode *fi) +{ + assert_spin_locked(&fi->lock); + if (fi->iocachectr > 0) + return false; + fi->iocachectr--; + return true; +} + +/* + * Release a request to deny open in caching mode. + * Return true if allowing new opens in caching mode. + */ +static inline bool fuse_inode_allow_io_cache(struct fuse_inode *fi) +{ + assert_spin_locked(&fi->lock); + if (WARN_ON(fi->iocachectr >= 0)) + return false; + return ++(fi->iocachectr) == 0; +} + +/* + * Return true if allowing new opens in caching mode. + */ +static inline bool fuse_is_io_cache_allowed(struct fuse_inode *fi) +{ + return READ_ONCE(fi->iocachectr) >= 0; +} struct fuse_file *fuse_file_open(struct fuse_mount *fm, u64 nodeid, unsigned int open_flags, bool isdir); diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h index e7418d15fe39..66a4bd8d767d 100644 --- a/include/uapi/linux/fuse.h +++ b/include/uapi/linux/fuse.h @@ -353,6 +353,7 @@ struct fuse_file_lock { * FOPEN_STREAM: the file is stream-like (no file position at all) * FOPEN_NOFLUSH: don't flush data cache on close (unless FUSE_WRITEBACK_CACHE) * FOPEN_PARALLEL_DIRECT_WRITES: Allow concurrent direct writes on the same inode + * FOPEN_CACHE_IO: using cache for this open file (incl. mmap on direct_io) */ #define FOPEN_DIRECT_IO (1 << 0) #define FOPEN_KEEP_CACHE (1 << 1) @@ -361,6 +362,7 @@ struct fuse_file_lock { #define FOPEN_STREAM (1 << 4) #define FOPEN_NOFLUSH (1 << 5) #define FOPEN_PARALLEL_DIRECT_WRITES (1 << 6) +#define FOPEN_CACHE_IO (1 << 7) /** * INIT request/reply flags