On Wed, 2021-12-22 at 23:23 +0000, David Howells wrote: > Do the following: > > (1) Fill out cachefiles_daemon_add_cache() so that it sets up the cache > directories and registers the cache with cachefiles. > > (2) Add a function to do the top-level part of cache withdrawal and > unregistration. > > (3) Add a function to sync a cache. > > Signed-off-by: David Howells <dhowells@xxxxxxxxxx> > cc: linux-cachefs@xxxxxxxxxx > Link: https://lore.kernel.org/r/163819633175.215744.10857127598041268340.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # v1 > Link: https://lore.kernel.org/r/163906935445.143852.15545194974036410029.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # v2 > Link: https://lore.kernel.org/r/163967142904.1823006.244055483596047072.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # v3 > --- > > fs/cachefiles/Makefile | 1 > fs/cachefiles/cache.c | 207 +++++++++++++++++++++++++++++++++++++++++++++ > fs/cachefiles/daemon.c | 8 +- > fs/cachefiles/interface.c | 18 ++++ > fs/cachefiles/internal.h | 9 ++ > 5 files changed, 240 insertions(+), 3 deletions(-) > create mode 100644 fs/cachefiles/interface.c > > diff --git a/fs/cachefiles/Makefile b/fs/cachefiles/Makefile > index e0b092ca077f..92af5daee8ce 100644 > --- a/fs/cachefiles/Makefile > +++ b/fs/cachefiles/Makefile > @@ -6,6 +6,7 @@ > cachefiles-y := \ > cache.o \ > daemon.o \ > + interface.o \ > main.o \ > namei.o \ > security.o > diff --git a/fs/cachefiles/cache.c b/fs/cachefiles/cache.c > index 73636f89eefa..0462e7af87fb 100644 > --- a/fs/cachefiles/cache.c > +++ b/fs/cachefiles/cache.c > @@ -10,6 +10,166 @@ > #include <linux/namei.h> > #include "internal.h" > > +/* > + * Bring a cache online. > + */ > +int cachefiles_add_cache(struct cachefiles_cache *cache) > +{ > + struct fscache_cache *cache_cookie; > + struct path path; > + struct kstatfs stats; > + struct dentry *graveyard, *cachedir, *root; > + const struct cred *saved_cred; > + int ret; > + > + _enter(""); > + > + cache_cookie = fscache_acquire_cache(cache->tag); > + if (IS_ERR(cache_cookie)) > + return PTR_ERR(cache_cookie); > + > + /* we want to work under the module's security ID */ > + ret = cachefiles_get_security_ID(cache); > + if (ret < 0) > + goto error_getsec; > + > + cachefiles_begin_secure(cache, &saved_cred); > + > + /* look up the directory at the root of the cache */ > + ret = kern_path(cache->rootdirname, LOOKUP_DIRECTORY, &path); > + if (ret < 0) > + goto error_open_root; > + > + cache->mnt = path.mnt; > + root = path.dentry; > + > + ret = -EINVAL; > + if (mnt_user_ns(path.mnt) != &init_user_ns) { > + pr_warn("File cache on idmapped mounts not supported"); > + goto error_unsupported; > + } > + > + /* check parameters */ > + ret = -EOPNOTSUPP; > + if (d_is_negative(root) || > + !d_backing_inode(root)->i_op->lookup || > + !d_backing_inode(root)->i_op->mkdir || > + !(d_backing_inode(root)->i_opflags & IOP_XATTR) || > + !root->d_sb->s_op->statfs || > + !root->d_sb->s_op->sync_fs || > + root->d_sb->s_blocksize > PAGE_SIZE) > + goto error_unsupported; > + That's quite a collection of tests. Most are obvious, but some comments explaining the need for others would not be a bad thing. In particular, why is s_blocksize > PAGE_SIZE unsupported? Also, should you vet whether the fs supports i_op->tmpfile here ? > + ret = -EROFS; > + if (sb_rdonly(root->d_sb)) > + goto error_unsupported; > + > + /* determine the security of the on-disk cache as this governs > + * security ID of files we create */ > + ret = cachefiles_determine_cache_security(cache, root, &saved_cred); > + if (ret < 0) > + goto error_unsupported; > + > + /* get the cache size and blocksize */ > + ret = vfs_statfs(&path, &stats); > + if (ret < 0) > + goto error_unsupported; > + > + ret = -ERANGE; > + if (stats.f_bsize <= 0) > + goto error_unsupported; > + > + ret = -EOPNOTSUPP; > + if (stats.f_bsize > PAGE_SIZE) > + goto error_unsupported; > + > + cache->bsize = stats.f_bsize; > + cache->bshift = 0; > + if (stats.f_bsize < PAGE_SIZE) > + cache->bshift = PAGE_SHIFT - ilog2(stats.f_bsize); > + > + _debug("blksize %u (shift %u)", > + cache->bsize, cache->bshift); > + > + _debug("size %llu, avail %llu", > + (unsigned long long) stats.f_blocks, > + (unsigned long long) stats.f_bavail); > + > + /* set up caching limits */ > + do_div(stats.f_files, 100); > + cache->fstop = stats.f_files * cache->fstop_percent; > + cache->fcull = stats.f_files * cache->fcull_percent; > + cache->frun = stats.f_files * cache->frun_percent; > + > + _debug("limits {%llu,%llu,%llu} files", > + (unsigned long long) cache->frun, > + (unsigned long long) cache->fcull, > + (unsigned long long) cache->fstop); > + > + stats.f_blocks >>= cache->bshift; > + do_div(stats.f_blocks, 100); > + cache->bstop = stats.f_blocks * cache->bstop_percent; > + cache->bcull = stats.f_blocks * cache->bcull_percent; > + cache->brun = stats.f_blocks * cache->brun_percent; > + > + _debug("limits {%llu,%llu,%llu} blocks", > + (unsigned long long) cache->brun, > + (unsigned long long) cache->bcull, > + (unsigned long long) cache->bstop); > + > + /* get the cache directory and check its type */ > + cachedir = cachefiles_get_directory(cache, root, "cache", NULL); > + if (IS_ERR(cachedir)) { > + ret = PTR_ERR(cachedir); > + goto error_unsupported; > + } > + > + cache->store = cachedir; > + > + /* get the graveyard directory */ > + graveyard = cachefiles_get_directory(cache, root, "graveyard", NULL); > + if (IS_ERR(graveyard)) { > + ret = PTR_ERR(graveyard); > + goto error_unsupported; > + } > + > + cache->graveyard = graveyard; > + cache->cache = cache_cookie; > + > + ret = fscache_add_cache(cache_cookie, &cachefiles_cache_ops, cache); > + if (ret < 0) > + goto error_add_cache; > + > + /* done */ > + set_bit(CACHEFILES_READY, &cache->flags); > + dput(root); > + > + pr_info("File cache on %s registered\n", cache_cookie->name); > + > + /* check how much space the cache has */ > + cachefiles_has_space(cache, 0, 0); > + cachefiles_end_secure(cache, saved_cred); > + _leave(" = 0 [%px]", cache->cache); > + return 0; > + > +error_add_cache: > + cachefiles_put_directory(cache->graveyard); > + cache->graveyard = NULL; > +error_unsupported: > + cachefiles_put_directory(cache->store); > + cache->store = NULL; > + mntput(cache->mnt); > + cache->mnt = NULL; > + dput(root); > +error_open_root: > + cachefiles_end_secure(cache, saved_cred); > +error_getsec: > + fscache_relinquish_cache(cache_cookie); > + cache->cache = NULL; > + pr_err("Failed to register: %d\n", ret); > + return ret; > +} > + > /* > * See if we have space for a number of pages and/or a number of files in the > * cache > @@ -101,3 +261,50 @@ int cachefiles_has_space(struct cachefiles_cache *cache, > _leave(" = %d", ret); > return ret; > } > + > +/* > + * Sync a cache to backing disk. > + */ > +static void cachefiles_sync_cache(struct cachefiles_cache *cache) > +{ > + const struct cred *saved_cred; > + int ret; > + > + _enter("%s", cache->cache->name); > + > + /* make sure all pages pinned by operations on behalf of the netfs are > + * written to disc */ > + cachefiles_begin_secure(cache, &saved_cred); > + down_read(&cache->mnt->mnt_sb->s_umount); > + ret = sync_filesystem(cache->mnt->mnt_sb); > + up_read(&cache->mnt->mnt_sb->s_umount); > + cachefiles_end_secure(cache, saved_cred); > + > + if (ret == -EIO) > + cachefiles_io_error(cache, > + "Attempt to sync backing fs superblock returned error %d", > + ret); > +} > + > +/* > + * Withdraw cache objects. > + */ > +void cachefiles_withdraw_cache(struct cachefiles_cache *cache) > +{ > + struct fscache_cache *fscache = cache->cache; > + > + pr_info("File cache on %s unregistering\n", fscache->name); > + > + fscache_withdraw_cache(fscache); > + > + /* we now have to destroy all the active objects pertaining to this > + * cache - which we do by passing them off to thread pool to be > + * disposed of */ > + // PLACEHOLDER: Withdraw objects > + fscache_wait_for_objects(fscache); > + > + // PLACEHOLDER: Withdraw volume > + cachefiles_sync_cache(cache); > + cache->cache = NULL; > + fscache_relinquish_cache(fscache); > +} > diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c > index 7d4691614cec..a449ee661987 100644 > --- a/fs/cachefiles/daemon.c > +++ b/fs/cachefiles/daemon.c > @@ -702,6 +702,7 @@ static int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args) > > pr_warn("Cache is disabled for development\n"); > return -ENOANO; // Don't allow the cache to operate yet > + //return cachefiles_add_cache(cache); > } > > /* > @@ -711,10 +712,11 @@ static void cachefiles_daemon_unbind(struct cachefiles_cache *cache) > { > _enter(""); > > - if (test_bit(CACHEFILES_READY, &cache->flags)) { > - // PLACEHOLDER: Withdraw cache > - } > + if (test_bit(CACHEFILES_READY, &cache->flags)) > + cachefiles_withdraw_cache(cache); > > + cachefiles_put_directory(cache->graveyard); > + cachefiles_put_directory(cache->store); > mntput(cache->mnt); > > kfree(cache->rootdirname); > diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c > new file mode 100644 > index 000000000000..564ea8fa6641 > --- /dev/null > +++ b/fs/cachefiles/interface.c > @@ -0,0 +1,18 @@ > +// SPDX-License-Identifier: GPL-2.0-or-later > +/* FS-Cache interface to CacheFiles > + * > + * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved. > + * Written by David Howells (dhowells@xxxxxxxxxx) > + */ > + > +#include <linux/slab.h> > +#include <linux/mount.h> > +#include <linux/xattr.h> > +#include <linux/file.h> > +#include <linux/falloc.h> > +#include <trace/events/fscache.h> > +#include "internal.h" > + > +const struct fscache_cache_ops cachefiles_cache_ops = { > + .name = "cachefiles", > +}; > diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h > index 48768a3ab105..77e874c2bbe7 100644 > --- a/fs/cachefiles/internal.h > +++ b/fs/cachefiles/internal.h > @@ -32,6 +32,8 @@ struct cachefiles_object { > struct cachefiles_cache { > struct fscache_cache *cache; /* Cache cookie */ > struct vfsmount *mnt; /* mountpoint holding the cache */ > + struct dentry *store; /* Directory into which live objects go */ > + struct dentry *graveyard; /* directory into which dead objects go */ > struct file *cachefilesd; /* manager daemon handle */ > const struct cred *cache_cred; /* security override for accessing cache */ > struct mutex daemon_mutex; /* command serialisation mutex */ > @@ -78,8 +80,10 @@ static inline void cachefiles_state_changed(struct cachefiles_cache *cache) > /* > * cache.c > */ > +extern int cachefiles_add_cache(struct cachefiles_cache *cache); > extern int cachefiles_has_space(struct cachefiles_cache *cache, > unsigned fnr, unsigned bnr); > +extern void cachefiles_withdraw_cache(struct cachefiles_cache *cache); > > /* > * daemon.c > @@ -125,6 +129,11 @@ static inline int cachefiles_inject_remove_error(void) > return cachefiles_error_injection_state & 2 ? -EIO : 0; > } > > +/* > + * interface.c > + */ > +extern const struct fscache_cache_ops cachefiles_cache_ops; > + > /* > * namei.c > */ > > -- Jeff Layton <jlayton@xxxxxxxxxx>
