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. 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, };
