[40/64] cachefiles: Implement cache registration and withdrawal

Message ID	163819633175.215744.10857127598041268340.stgit@warthog.procyon.org.uk (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-fsdevel-owner@kernel.org> Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH 40/64] cachefiles: Implement cache registration and withdrawal From: David Howells <dhowells@redhat.com> To: linux-cachefs@redhat.com Cc: dhowells@redhat.com, Trond Myklebust <trondmy@hammerspace.com>, Anna Schumaker <anna.schumaker@netapp.com>, Steve French <sfrench@samba.org>, Dominique Martinet <asmadeus@codewreck.org>, Jeff Layton <jlayton@kernel.org>, Matthew Wilcox <willy@infradead.org>, Alexander Viro <viro@zeniv.linux.org.uk>, Omar Sandoval <osandov@osandov.com>, Linus Torvalds <torvalds@linux-foundation.org>, linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Date: Mon, 29 Nov 2021 14:32:11 +0000 Message-ID: <163819633175.215744.10857127598041268340.stgit@warthog.procyon.org.uk> In-Reply-To: <163819575444.215744.318477214576928110.stgit@warthog.procyon.org.uk> References: <163819575444.215744.318477214576928110.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.23 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk
Series	fscache, cachefiles: Rewrite \| expand [00/64] fscache, cachefiles: Rewrite [01/64] fscache, cachefiles: Disable configuration [02/64] cachefiles: Delete the cachefiles driver pending rewrite [03/64] fscache: Remove the contents of the fscache driver, pending rewrite [04/64] netfs: Display the netfs inode number in the netfs_read tracepoint [05/64] netfs: Pass a flag to ->prepare_write() to say if there's no alloc'd space [06/64] fscache: Introduce new driver [07/64] fscache: Implement a hash function [08/64] fscache: Implement cache registration [09/64] fscache: Implement volume registration [10/64] fscache: Implement cookie registration [11/64] fscache: Implement cache-level access helpers [12/64] fscache: Implement volume-level access helpers [13/64] fscache: Implement cookie-level access helpers [14/64] fscache: Implement functions add/remove a cache [15/64] fscache: Provide and use cache methods to lookup/create/free a volume [16/64] fscache: Add a function for a cache backend to note an I/O error [17/64] fscache: Implement simple cookie state machine [18/64] fscache: Implement cookie user counting and resource pinning [19/64] fscache: Implement cookie invalidation [20/64] fscache: Provide a means to begin an operation [21/64] fscache: Count data storage objects in a cache [22/64] fscache: Provide read/write stat counters for the cache [23/64] fscache: Provide a function to let the netfs update its coherency data [24/64] netfs: Pass more information on how to deal with a hole in the cache [25/64] fscache: Implement raw I/O interface [26/64] fscache: Implement higher-level write I/O interface [27/64] vfs, fscache: Implement pinning of cache usage for writeback [28/64] fscache: Provide a function to note the release of a page [29/64] fscache: Provide a function to resize a cookie [30/64] cachefiles: Introduce rewritten driver [31/64] cachefiles: Define structs [32/64] cachefiles: Add some error injection support [33/64] cachefiles: Add a couple of tracepoints for logging errors [34/64] cachefiles: Add cache error reporting macro [35/64] cachefiles: Add security derivation [36/64] cachefiles: Register a miscdev and parse commands over it [37/64] cachefiles: Provide a function to check how much space there is [38/64] vfs, cachefiles: Mark a backing file in use with an inode flag [39/64] cachefiles: Implement a function to get/create a directory in the cache [40/64] cachefiles: Implement cache registration and withdrawal [41/64] cachefiles: Implement volume support [42/64] cachefiles: Add tracepoints for calls to the VFS [43/64] cachefiles: Implement object lifecycle funcs [44/64] cachefiles: Implement key to filename encoding [45/64] cachefiles: Implement metadata/coherency data storage in xattrs [46/64] cachefiles: Mark a backing file in use with an inode flag [47/64] cachefiles: Implement culling daemon commands [48/64] cachefiles: Implement backing file wrangling [49/64] cachefiles: Implement begin and end I/O operation [50/64] cachefiles: Implement cookie resize for truncate [51/64] cachefiles: Implement the I/O routines [52/64] cachefiles: Allow cachefiles to actually function [53/64] fscache, cachefiles: Display stats of no-space events [54/64] fscache, cachefiles: Display stat of culling events [55/64] afs: Handle len being extending over page end in write_begin/write_end [56/64] afs: Fix afs_write_end() to handle len > page size [57/64] afs: Convert afs to use the new fscache API [58/64] afs: Copy local writes to the cache when writing to the server [59/64] afs: Skip truncation on the server of data we haven't written yet [60/64] 9p: Use fscache indexing rewrite and reenable caching [61/64] 9p: Copy local writes to the cache when writing to the server [62/64] nfs: Convert to new fscache volume/cookie API [63/64] cifs: Support fscache indexing rewrite (untested) [64/64] fscache: Rewrite documentation

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..4c4121105750 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; + + 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"); + 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"); + 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@redhat.com) + */ + +#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 65e01ac1da39..0ccea2373b40 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 */

[40/64] cachefiles: Implement cache registration and withdrawal

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