cachefiles: Delete the cachefiles driver pending rewrite

Delete the code from the cachefiles driver to make it easier to rewrite and
resubmit in a logical manner.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/163819577641.215744.12718114397770666596.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906883770.143852.4149714614981373410.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967076066.1823006.7175712134577687753.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021483619.640689.7586546280515844702.stgit@warthog.procyon.org.uk/ # v4

fs/Kconfig

@@ -132,7 +132,6 @@ menu "Caches"
 
 source "fs/netfs/Kconfig"
 source "fs/fscache/Kconfig"
-source "fs/cachefiles/Kconfig"
 
 endmenu
 

fs/Makefile

@@ -125,7 +125,6 @@ obj-$(CONFIG_AFS_FS)		+= afs/
 obj-$(CONFIG_NILFS2_FS)		+= nilfs2/
 obj-$(CONFIG_BEFS_FS)		+= befs/
 obj-$(CONFIG_HOSTFS)		+= hostfs/
-obj-$(CONFIG_CACHEFILES)	+= cachefiles/
 obj-$(CONFIG_DEBUG_FS)		+= debugfs/
 obj-$(CONFIG_TRACING)		+= tracefs/
 obj-$(CONFIG_OCFS2_FS)		+= ocfs2/

fs/cachefiles/Kconfig

-# SPDX-License-Identifier: GPL-2.0-only
-
-config CACHEFILES
-	tristate "Filesystem caching on files"
-	depends on FSCACHE && BLOCK
-	help
-	  This permits use of a mounted filesystem as a cache for other
-	  filesystems - primarily networking filesystems - thus allowing fast
-	  local disk to enhance the speed of slower devices.
-
-	  See Documentation/filesystems/caching/cachefiles.rst for more
-	  information.
-
-config CACHEFILES_DEBUG
-	bool "Debug CacheFiles"
-	depends on CACHEFILES
-	help
-	  This permits debugging to be dynamically enabled in the filesystem
-	  caching on files module.  If this is set, the debugging output may be
-	  enabled by setting bits in /sys/modules/cachefiles/parameter/debug or
-	  by including a debugging specifier in /etc/cachefilesd.conf.

fs/cachefiles/Makefile

-# SPDX-License-Identifier: GPL-2.0
-#
-# Makefile for caching in a mounted filesystem
-#
-
-cachefiles-y := \
-	bind.o \
-	daemon.o \
-	interface.o \
-	io.o \
-	key.o \
-	main.o \
-	namei.o \
-	rdwr.o \
-	security.o \
-	xattr.o
-
-obj-$(CONFIG_CACHEFILES) := cachefiles.o

fs/cachefiles/bind.c

-// SPDX-License-Identifier: GPL-2.0-or-later
-/* Bind and unbind a cache from the filesystem backing it
- *
- * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
- * Written by David Howells (dhowells@redhat.com)
- */
-
-#include <linux/module.h>
-#include <linux/init.h>
-#include <linux/sched.h>
-#include <linux/completion.h>
-#include <linux/slab.h>
-#include <linux/fs.h>
-#include <linux/file.h>
-#include <linux/namei.h>
-#include <linux/mount.h>
-#include <linux/statfs.h>
-#include <linux/ctype.h>
-#include <linux/xattr.h>
-#include "internal.h"
-
-static int cachefiles_daemon_add_cache(struct cachefiles_cache *caches);
-
-/*
- * bind a directory as a cache
- */
-int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args)
-{
-	_enter("{%u,%u,%u,%u,%u,%u},%s",
-	       cache->frun_percent,
-	       cache->fcull_percent,
-	       cache->fstop_percent,
-	       cache->brun_percent,
-	       cache->bcull_percent,
-	       cache->bstop_percent,
-	       args);
-
-	/* start by checking things over */
-	ASSERT(cache->fstop_percent >= 0 &&
-	       cache->fstop_percent < cache->fcull_percent &&
-	       cache->fcull_percent < cache->frun_percent &&
-	       cache->frun_percent  < 100);
-
-	ASSERT(cache->bstop_percent >= 0 &&
-	       cache->bstop_percent < cache->bcull_percent &&
-	       cache->bcull_percent < cache->brun_percent &&
-	       cache->brun_percent  < 100);
-
-	if (*args) {
-		pr_err("'bind' command doesn't take an argument\n");
-		return -EINVAL;
-	}
-
-	if (!cache->rootdirname) {
-		pr_err("No cache directory specified\n");
-		return -EINVAL;
-	}
-
-	/* don't permit already bound caches to be re-bound */
-	if (test_bit(CACHEFILES_READY, &cache->flags)) {
-		pr_err("Cache already bound\n");
-		return -EBUSY;
-	}
-
-	/* make sure we have copies of the tag and dirname strings */
-	if (!cache->tag) {
-		/* the tag string is released by the fops->release()
-		 * function, so we don't release it on error here */
-		cache->tag = kstrdup("CacheFiles", GFP_KERNEL);
-		if (!cache->tag)
-			return -ENOMEM;
-	}
-
-	/* add the cache */
-	return cachefiles_daemon_add_cache(cache);
-}
-
-/*
- * add a cache
- */
-static int cachefiles_daemon_add_cache(struct cachefiles_cache *cache)
-{
-	struct cachefiles_object *fsdef;
-	struct path path;
-	struct kstatfs stats;
-	struct dentry *graveyard, *cachedir, *root;
-	const struct cred *saved_cred;
-	int ret;
-
-	_enter("");
-
-	/* we want to work under the module's security ID */
-	ret = cachefiles_get_security_ID(cache);
-	if (ret < 0)
-		return ret;
-
-	cachefiles_begin_secure(cache, &saved_cred);
-
-	/* allocate the root index object */
-	ret = -ENOMEM;
-
-	fsdef = kmem_cache_alloc(cachefiles_object_jar, GFP_KERNEL);
-	if (!fsdef)
-		goto error_root_object;
-
-	ASSERTCMP(fsdef->backer, ==, NULL);
-
-	atomic_set(&fsdef->usage, 1);
-	fsdef->type = FSCACHE_COOKIE_TYPE_INDEX;
-
-	/* 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)
-		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;
-	}
-
-	fsdef->dentry = cachedir;
-	fsdef->fscache.cookie = NULL;
-
-	ret = cachefiles_check_object_type(fsdef);
-	if (ret < 0)
-		goto error_unsupported;
-
-	/* 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;
-
-	/* publish the cache */
-	fscache_init_cache(&cache->cache,
-			   &cachefiles_cache_ops,
-			   "%s",
-			   fsdef->dentry->d_sb->s_id);
-
-	fscache_object_init(&fsdef->fscache, &fscache_fsdef_index,
-			    &cache->cache);
-
-	ret = fscache_add_cache(&cache->cache, &fsdef->fscache, cache->tag);
-	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->cache.identifier);
-
-	/* check how much space the cache has */
-	cachefiles_has_space(cache, 0, 0);
-	cachefiles_end_secure(cache, saved_cred);
-	return 0;
-
-error_add_cache:
-	dput(cache->graveyard);
-	cache->graveyard = NULL;
-error_unsupported:
-	mntput(cache->mnt);
-	cache->mnt = NULL;
-	dput(fsdef->dentry);
-	fsdef->dentry = NULL;
-	dput(root);
-error_open_root:
-	kmem_cache_free(cachefiles_object_jar, fsdef);
-error_root_object:
-	cachefiles_end_secure(cache, saved_cred);
-	pr_err("Failed to register: %d\n", ret);
-	return ret;
-}
-
-/*
- * unbind a cache on fd release
- */
-void cachefiles_daemon_unbind(struct cachefiles_cache *cache)
-{
-	_enter("");
-
-	if (test_bit(CACHEFILES_READY, &cache->flags)) {
-		pr_info("File cache on %s unregistering\n",
-			cache->cache.identifier);
-
-		fscache_withdraw_cache(&cache->cache);
-	}
-
-	dput(cache->graveyard);
-	mntput(cache->mnt);
-
-	kfree(cache->rootdirname);
-	kfree(cache->secctx);
-	kfree(cache->tag);
-
-	_leave("");
-}

fs/cachefiles/key.c

-// SPDX-License-Identifier: GPL-2.0-or-later
-/* Key to pathname encoder
- *
- * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
- * Written by David Howells (dhowells@redhat.com)
- */
-
-#include <linux/slab.h>
-#include "internal.h"
-
-static const char cachefiles_charmap[64] =
-	"0123456789"			/* 0 - 9 */
-	"abcdefghijklmnopqrstuvwxyz"	/* 10 - 35 */
-	"ABCDEFGHIJKLMNOPQRSTUVWXYZ"	/* 36 - 61 */
-	"_-"				/* 62 - 63 */
-	;
-
-static const char cachefiles_filecharmap[256] = {
-	/* we skip space and tab and control chars */
-	[33 ... 46] = 1,		/* '!' -> '.' */
-	/* we skip '/' as it's significant to pathwalk */
-	[48 ... 127] = 1,		/* '0' -> '~' */
-};
-
-/*
- * turn the raw key into something cooked
- * - the raw key should include the length in the two bytes at the front
- * - the key may be up to 514 bytes in length (including the length word)
- *   - "base64" encode the strange keys, mapping 3 bytes of raw to four of
- *     cooked
- *   - need to cut the cooked key into 252 char lengths (189 raw bytes)
- */
-char *cachefiles_cook_key(const u8 *raw, int keylen, uint8_t type)
-{
-	unsigned char csum, ch;
-	unsigned int acc;
-	char *key;
-	int loop, len, max, seg, mark, print;
-
-	_enter(",%d", keylen);
-
-	BUG_ON(keylen < 2 || keylen > 514);
-
-	csum = raw[0] + raw[1];
-	print = 1;
-	for (loop = 2; loop < keylen; loop++) {
-		ch = raw[loop];
-		csum += ch;
-		print &= cachefiles_filecharmap[ch];
-	}
-
-	if (print) {
-		/* if the path is usable ASCII, then we render it directly */
-		max = keylen - 2;
-		max += 2;	/* two base64'd length chars on the front */
-		max += 5;	/* @checksum/M */
-		max += 3 * 2;	/* maximum number of segment dividers (".../M")
-				 * is ((514 + 251) / 252) = 3
-				 */
-		max += 1;	/* NUL on end */
-	} else {
-		/* calculate the maximum length of the cooked key */
-		keylen = (keylen + 2) / 3;
-
-		max = keylen * 4;
-		max += 5;	/* @checksum/M */
-		max += 3 * 2;	/* maximum number of segment dividers (".../M")
-				 * is ((514 + 188) / 189) = 3
-				 */
-		max += 1;	/* NUL on end */
-	}
-
-	max += 1;	/* 2nd NUL on end */
-
-	_debug("max: %d", max);
-
-	key = kmalloc(max, cachefiles_gfp);
-	if (!key)
-		return NULL;
-
-	len = 0;
-
-	/* build the cooked key */
-	sprintf(key, "@%02x%c+", (unsigned) csum, 0);
-	len = 5;
-	mark = len - 1;
-
-	if (print) {
-		acc = *(uint16_t *) raw;
-		raw += 2;
-
-		key[len + 1] = cachefiles_charmap[acc & 63];
-		acc >>= 6;
-		key[len] = cachefiles_charmap[acc & 63];
-		len += 2;
-
-		seg = 250;
-		for (loop = keylen; loop > 0; loop--) {
-			if (seg <= 0) {
-				key[len++] = '\0';
-				mark = len;
-				key[len++] = '+';
-				seg = 252;
-			}
-
-			key[len++] = *raw++;
-			ASSERT(len < max);
-		}
-
-		switch (type) {
-		case FSCACHE_COOKIE_TYPE_INDEX:		type = 'I';	break;
-		case FSCACHE_COOKIE_TYPE_DATAFILE:	type = 'D';	break;
-		default:				type = 'S';	break;
-		}
-	} else {
-		seg = 252;
-		for (loop = keylen; loop > 0; loop--) {
-			if (seg <= 0) {
-				key[len++] = '\0';
-				mark = len;
-				key[len++] = '+';
-				seg = 252;
-			}
-
-			acc = *raw++;
-			acc |= *raw++ << 8;
-			acc |= *raw++ << 16;
-
-			_debug("acc: %06x", acc);
-
-			key[len++] = cachefiles_charmap[acc & 63];
-			acc >>= 6;
-			key[len++] = cachefiles_charmap[acc & 63];
-			acc >>= 6;
-			key[len++] = cachefiles_charmap[acc & 63];
-			acc >>= 6;
-			key[len++] = cachefiles_charmap[acc & 63];
-
-			ASSERT(len < max);
-		}
-
-		switch (type) {
-		case FSCACHE_COOKIE_TYPE_INDEX:		type = 'J';	break;
-		case FSCACHE_COOKIE_TYPE_DATAFILE:	type = 'E';	break;
-		default:				type = 'T';	break;
-		}
-	}
-
-	key[mark] = type;
-	key[len++] = 0;
-	key[len] = 0;
-
-	_leave(" = %s %d", key, len);
-	return key;
-}

fs/cachefiles/main.c

-// SPDX-License-Identifier: GPL-2.0-or-later
-/* Network filesystem caching backend to use cache files on a premounted
- * filesystem
- *
- * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
- * Written by David Howells (dhowells@redhat.com)
- */
-
-#include <linux/module.h>
-#include <linux/init.h>
-#include <linux/sched.h>
-#include <linux/completion.h>
-#include <linux/slab.h>
-#include <linux/fs.h>
-#include <linux/file.h>
-#include <linux/namei.h>
-#include <linux/mount.h>
-#include <linux/statfs.h>
-#include <linux/sysctl.h>
-#include <linux/miscdevice.h>
-#define CREATE_TRACE_POINTS
-#include "internal.h"
-
-unsigned cachefiles_debug;
-module_param_named(debug, cachefiles_debug, uint, S_IWUSR | S_IRUGO);
-MODULE_PARM_DESC(cachefiles_debug, "CacheFiles debugging mask");
-
-MODULE_DESCRIPTION("Mounted-filesystem based cache");
-MODULE_AUTHOR("Red Hat, Inc.");
-MODULE_LICENSE("GPL");
-
-struct kmem_cache *cachefiles_object_jar;
-
-static struct miscdevice cachefiles_dev = {
-	.minor	= MISC_DYNAMIC_MINOR,
-	.name	= "cachefiles",
-	.fops	= &cachefiles_daemon_fops,
-};
-
-static void cachefiles_object_init_once(void *_object)
-{
-	struct cachefiles_object *object = _object;
-
-	memset(object, 0, sizeof(*object));
-	spin_lock_init(&object->work_lock);
-}
-
-/*
- * initialise the fs caching module
- */
-static int __init cachefiles_init(void)
-{
-	int ret;
-
-	ret = misc_register(&cachefiles_dev);
-	if (ret < 0)
-		goto error_dev;
-
-	/* create an object jar */
-	ret = -ENOMEM;
-	cachefiles_object_jar =
-		kmem_cache_create("cachefiles_object_jar",
-				  sizeof(struct cachefiles_object),
-				  0,
-				  SLAB_HWCACHE_ALIGN,
-				  cachefiles_object_init_once);
-	if (!cachefiles_object_jar) {
-		pr_notice("Failed to allocate an object jar\n");
-		goto error_object_jar;
-	}
-
-	pr_info("Loaded\n");
-	return 0;
-
-error_object_jar:
-	misc_deregister(&cachefiles_dev);
-error_dev:
-	pr_err("failed to register: %d\n", ret);
-	return ret;
-}
-
-fs_initcall(cachefiles_init);
-
-/*
- * clean up on module removal
- */
-static void __exit cachefiles_exit(void)
-{
-	pr_info("Unloading\n");
-
-	kmem_cache_destroy(cachefiles_object_jar);
-	misc_deregister(&cachefiles_dev);
-}
-
-module_exit(cachefiles_exit);

fs/cachefiles/security.c

-// SPDX-License-Identifier: GPL-2.0-or-later
-/* CacheFiles security management
- *
- * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
- * Written by David Howells (dhowells@redhat.com)
- */
-
-#include <linux/fs.h>
-#include <linux/cred.h>
-#include "internal.h"
-
-/*
- * determine the security context within which we access the cache from within
- * the kernel
- */
-int cachefiles_get_security_ID(struct cachefiles_cache *cache)
-{
-	struct cred *new;
-	int ret;
-
-	_enter("{%s}", cache->secctx);
-
-	new = prepare_kernel_cred(current);
-	if (!new) {
-		ret = -ENOMEM;
-		goto error;
-	}
-
-	if (cache->secctx) {
-		ret = set_security_override_from_ctx(new, cache->secctx);
-		if (ret < 0) {
-			put_cred(new);
-			pr_err("Security denies permission to nominate security context: error %d\n",
-			       ret);
-			goto error;
-		}
-	}
-
-	cache->cache_cred = new;
-	ret = 0;
-error:
-	_leave(" = %d", ret);
-	return ret;
-}
-
-/*
- * see if mkdir and create can be performed in the root directory
- */
-static int cachefiles_check_cache_dir(struct cachefiles_cache *cache,
-				      struct dentry *root)
-{
-	int ret;
-
-	ret = security_inode_mkdir(d_backing_inode(root), root, 0);
-	if (ret < 0) {
-		pr_err("Security denies permission to make dirs: error %d",
-		       ret);
-		return ret;
-	}
-
-	ret = security_inode_create(d_backing_inode(root), root, 0);
-	if (ret < 0)
-		pr_err("Security denies permission to create files: error %d",
-		       ret);
-
-	return ret;
-}
-
-/*
- * check the security details of the on-disk cache
- * - must be called with security override in force
- * - must return with a security override in force - even in the case of an
- *   error
- */
-int cachefiles_determine_cache_security(struct cachefiles_cache *cache,
-					struct dentry *root,
-					const struct cred **_saved_cred)
-{
-	struct cred *new;
-	int ret;
-
-	_enter("");
-
-	/* duplicate the cache creds for COW (the override is currently in
-	 * force, so we can use prepare_creds() to do this) */
-	new = prepare_creds();
-	if (!new)
-		return -ENOMEM;
-
-	cachefiles_end_secure(cache, *_saved_cred);
-
-	/* use the cache root dir's security context as the basis with
-	 * which create files */
-	ret = set_create_files_as(new, d_backing_inode(root));
-	if (ret < 0) {
-		abort_creds(new);
-		cachefiles_begin_secure(cache, _saved_cred);
-		_leave(" = %d [cfa]", ret);
-		return ret;
-	}
-
-	put_cred(cache->cache_cred);
-	cache->cache_cred = new;
-
-	cachefiles_begin_secure(cache, _saved_cred);
-	ret = cachefiles_check_cache_dir(cache, root);
-
-	if (ret == -EOPNOTSUPP)
-		ret = 0;
-	_leave(" = %d", ret);
-	return ret;
-}