Hi Miklos, On Wed, Feb 26 2025, Luis Henriques wrote: > Currently userspace is able to notify the kernel to invalidate the cache > for an inode. This means that, if all the inodes in a filesystem need to > be invalidated, then userspace needs to iterate through all of them and do > this kernel notification separately. > > This patch adds the concept of 'epoch': each fuse connection will have the > current epoch initialized and every new dentry will have it's d_time set to > the current epoch value. A new operation will then allow userspace to > increment the epoch value. Every time a dentry is d_revalidate()'ed, it's > epoch is compared with the current connection epoch and invalidated if it's > value is different. Any further feedback on this patch, or is it already OK for being merged? And what about the extra call to shrink_dcache_sb(), do you think that would that be acceptable? Maybe that could be conditional, by for example setting a flag. Cheers, -- Luís > Signed-off-by: Luis Henriques <luis@xxxxxxxxxx> > --- > Nothing huge since v7, I just realized I forgot to bump the version number > while cleaning up a patch to prepare a libfuse MR. > > * Changes since v7 > - Bump FUSE interface minor number > > * Changes since v6 > - Major patch re-write, following a different approach suggested by Miklos > and Dave. > > * Changes since v5 > - Added missing iput() in function fuse_reverse_inval_all() > > * Changes since v4 > - Replaced superblock inodes iteration by a single call to > invalidate_inodes(). Also do the shrink_dcache_sb() first. (Dave Chinner) > > * Changes since v3 > - Added comments to clarify semantic changes in fuse_reverse_inval_inode() > when called with FUSE_INVAL_ALL_INODES (suggested by Bernd). > - Added comments to inodes iteration loop to clarify __iget/iput usage > (suggested by Joanne) > - Dropped get_fuse_mount() call -- fuse_mount can be obtained from > fuse_ilookup() directly (suggested by Joanne) > > (Also dropped the RFC from the subject.) > > * Changes since v2 > - Use the new helper from fuse_reverse_inval_inode(), as suggested by Bernd. > - Also updated patch description as per checkpatch.pl suggestion. > > * Changes since v1 > As suggested by Bernd, this patch v2 simply adds an helper function that > will make it easier to replace most of it's code by a call to function > super_iter_inodes() when Dave Chinner's patch[1] eventually gets merged. > > [1] https://lore.kernel.org/r/20241002014017.3801899-3-david@xxxxxxxxxxxxx > > fs/fuse/dev.c | 16 ++++++++++++++++ > fs/fuse/dir.c | 22 +++++++++++++++++++--- > fs/fuse/fuse_i.h | 3 +++ > fs/fuse/inode.c | 1 + > fs/fuse/readdir.c | 3 +++ > include/uapi/linux/fuse.h | 6 +++++- > 6 files changed, 47 insertions(+), 4 deletions(-) > > diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c > index 5b5f789b37eb..e31a55ac3887 100644 > --- a/fs/fuse/dev.c > +++ b/fs/fuse/dev.c > @@ -1902,6 +1902,19 @@ static int fuse_notify_resend(struct fuse_conn *fc) > return 0; > } > > +/* > + * Increments the fuse connection epoch. This will result of dentries from > + * previous epochs to be invalidated. > + * > + * XXX optimization: add call to shrink_dcache_sb()? > + */ > +static int fuse_notify_inc_epoch(struct fuse_conn *fc) > +{ > + atomic_inc(&fc->epoch); > + > + return 0; > +} > + > static int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code, > unsigned int size, struct fuse_copy_state *cs) > { > @@ -1930,6 +1943,9 @@ static int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code, > case FUSE_NOTIFY_RESEND: > return fuse_notify_resend(fc); > > + case FUSE_NOTIFY_INC_EPOCH: > + return fuse_notify_inc_epoch(fc); > + > default: > fuse_copy_finish(cs); > return -EINVAL; > diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c > index 198862b086ff..5291deeb191f 100644 > --- a/fs/fuse/dir.c > +++ b/fs/fuse/dir.c > @@ -200,9 +200,14 @@ static int fuse_dentry_revalidate(struct inode *dir, const struct qstr *name, > { > struct inode *inode; > struct fuse_mount *fm; > + struct fuse_conn *fc; > struct fuse_inode *fi; > int ret; > > + fc = get_fuse_conn_super(dir->i_sb); > + if (entry->d_time < atomic_read(&fc->epoch)) > + goto invalid; > + > inode = d_inode_rcu(entry); > if (inode && fuse_is_bad(inode)) > goto invalid; > @@ -415,16 +420,20 @@ int fuse_lookup_name(struct super_block *sb, u64 nodeid, const struct qstr *name > static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry, > unsigned int flags) > { > - int err; > struct fuse_entry_out outarg; > + struct fuse_conn *fc; > struct inode *inode; > struct dentry *newent; > + int err, epoch; > bool outarg_valid = true; > bool locked; > > if (fuse_is_bad(dir)) > return ERR_PTR(-EIO); > > + fc = get_fuse_conn_super(dir->i_sb); > + epoch = atomic_read(&fc->epoch); > + > locked = fuse_lock_inode(dir); > err = fuse_lookup_name(dir->i_sb, get_node_id(dir), &entry->d_name, > &outarg, &inode); > @@ -446,6 +455,7 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry, > goto out_err; > > entry = newent ? newent : entry; > + entry->d_time = epoch; > if (outarg_valid) > fuse_change_entry_timeout(entry, &outarg); > else > @@ -619,7 +629,6 @@ static int fuse_create_open(struct mnt_idmap *idmap, struct inode *dir, > struct dentry *entry, struct file *file, > unsigned int flags, umode_t mode, u32 opcode) > { > - int err; > struct inode *inode; > struct fuse_mount *fm = get_fuse_mount(dir); > FUSE_ARGS(args); > @@ -629,11 +638,13 @@ static int fuse_create_open(struct mnt_idmap *idmap, struct inode *dir, > struct fuse_entry_out outentry; > struct fuse_inode *fi; > struct fuse_file *ff; > + int epoch, err; > bool trunc = flags & O_TRUNC; > > /* Userspace expects S_IFREG in create mode */ > BUG_ON((mode & S_IFMT) != S_IFREG); > > + epoch = atomic_read(&fm->fc->epoch); > forget = fuse_alloc_forget(); > err = -ENOMEM; > if (!forget) > @@ -702,6 +713,7 @@ static int fuse_create_open(struct mnt_idmap *idmap, struct inode *dir, > } > kfree(forget); > d_instantiate(entry, inode); > + entry->d_time = epoch; > fuse_change_entry_timeout(entry, &outentry); > fuse_dir_changed(dir); > err = generic_file_open(inode, file); > @@ -788,12 +800,14 @@ static int create_new_entry(struct mnt_idmap *idmap, struct fuse_mount *fm, > struct fuse_entry_out outarg; > struct inode *inode; > struct dentry *d; > - int err; > struct fuse_forget_link *forget; > + int epoch, err; > > if (fuse_is_bad(dir)) > return -EIO; > > + epoch = atomic_read(&fm->fc->epoch); > + > forget = fuse_alloc_forget(); > if (!forget) > return -ENOMEM; > @@ -836,9 +850,11 @@ static int create_new_entry(struct mnt_idmap *idmap, struct fuse_mount *fm, > return PTR_ERR(d); > > if (d) { > + d->d_time = epoch; > fuse_change_entry_timeout(d, &outarg); > dput(d); > } else { > + entry->d_time = epoch; > fuse_change_entry_timeout(entry, &outarg); > } > fuse_dir_changed(dir); > diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h > index fee96fe7887b..06eecc125f89 100644 > --- a/fs/fuse/fuse_i.h > +++ b/fs/fuse/fuse_i.h > @@ -611,6 +611,9 @@ struct fuse_conn { > /** Number of fuse_dev's */ > atomic_t dev_count; > > + /** Current epoch for up-to-date dentries */ > + atomic_t epoch; > + > struct rcu_head rcu; > > /** The user id for this mount */ > diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c > index e9db2cb8c150..5d2d29fad658 100644 > --- a/fs/fuse/inode.c > +++ b/fs/fuse/inode.c > @@ -959,6 +959,7 @@ void fuse_conn_init(struct fuse_conn *fc, struct fuse_mount *fm, > init_rwsem(&fc->killsb); > refcount_set(&fc->count, 1); > atomic_set(&fc->dev_count, 1); > + atomic_set(&fc->epoch, 1); > init_waitqueue_head(&fc->blocked_waitq); > fuse_iqueue_init(&fc->iq, fiq_ops, fiq_priv); > INIT_LIST_HEAD(&fc->bg_queue); > diff --git a/fs/fuse/readdir.c b/fs/fuse/readdir.c > index 17ce9636a2b1..46b7146f2c0d 100644 > --- a/fs/fuse/readdir.c > +++ b/fs/fuse/readdir.c > @@ -161,6 +161,7 @@ static int fuse_direntplus_link(struct file *file, > struct fuse_conn *fc; > struct inode *inode; > DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); > + int epoch; > > if (!o->nodeid) { > /* > @@ -190,6 +191,7 @@ static int fuse_direntplus_link(struct file *file, > return -EIO; > > fc = get_fuse_conn(dir); > + epoch = atomic_read(&fc->epoch); > > name.hash = full_name_hash(parent, name.name, name.len); > dentry = d_lookup(parent, &name); > @@ -256,6 +258,7 @@ static int fuse_direntplus_link(struct file *file, > } > if (fc->readdirplus_auto) > set_bit(FUSE_I_INIT_RDPLUS, &get_fuse_inode(inode)->state); > + dentry->d_time = epoch; > fuse_change_entry_timeout(dentry, o); > > dput(dentry); > diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h > index 5e0eb41d967e..15991728a894 100644 > --- a/include/uapi/linux/fuse.h > +++ b/include/uapi/linux/fuse.h > @@ -229,6 +229,9 @@ > * - FUSE_URING_IN_OUT_HEADER_SZ > * - FUSE_URING_OP_IN_OUT_SZ > * - enum fuse_uring_cmd > + * > + * 7.43 > + * - add FUSE_NOTIFY_INC_EPOCH > */ > > #ifndef _LINUX_FUSE_H > @@ -264,7 +267,7 @@ > #define FUSE_KERNEL_VERSION 7 > > /** Minor version number of this interface */ > -#define FUSE_KERNEL_MINOR_VERSION 42 > +#define FUSE_KERNEL_MINOR_VERSION 43 > > /** The node ID of the root inode */ > #define FUSE_ROOT_ID 1 > @@ -666,6 +669,7 @@ enum fuse_notify_code { > FUSE_NOTIFY_RETRIEVE = 5, > FUSE_NOTIFY_DELETE = 6, > FUSE_NOTIFY_RESEND = 7, > + FUSE_NOTIFY_INC_EPOCH = 8, > FUSE_NOTIFY_CODE_MAX, > }; > >
