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![David Howells](/assets/img/avatar_default.png)
Add a check that the backing filesystem supports the creation of tmpfiles[1]. Suggested-by: Jeff Layton <jlayton@kernel.org> 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/568749bd7cc02908ecf6f3d6a611b6f9cf5c4afd.camel@kernel.org/ [1] Link: https://lore.kernel.org/r/164251406558.3435901.1249023136670058162.stgit@warthog.procyon.org.uk/ # v1
383 lines
9.6 KiB
C
383 lines
9.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* Manage high-level VFS aspects of a cache.
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*
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* Copyright (C) 2007, 2021 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#include <linux/slab.h>
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#include <linux/statfs.h>
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#include <linux/namei.h>
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#include "internal.h"
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/*
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* Bring a cache online.
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*/
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int cachefiles_add_cache(struct cachefiles_cache *cache)
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{
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struct fscache_cache *cache_cookie;
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struct path path;
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struct kstatfs stats;
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struct dentry *graveyard, *cachedir, *root;
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const struct cred *saved_cred;
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int ret;
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_enter("");
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cache_cookie = fscache_acquire_cache(cache->tag);
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if (IS_ERR(cache_cookie))
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return PTR_ERR(cache_cookie);
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/* we want to work under the module's security ID */
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ret = cachefiles_get_security_ID(cache);
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if (ret < 0)
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goto error_getsec;
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cachefiles_begin_secure(cache, &saved_cred);
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/* look up the directory at the root of the cache */
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ret = kern_path(cache->rootdirname, LOOKUP_DIRECTORY, &path);
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if (ret < 0)
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goto error_open_root;
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cache->mnt = path.mnt;
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root = path.dentry;
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ret = -EINVAL;
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if (is_idmapped_mnt(path.mnt)) {
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pr_warn("File cache on idmapped mounts not supported");
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goto error_unsupported;
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}
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/* Check features of the backing filesystem:
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* - Directories must support looking up and directory creation
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* - We create tmpfiles to handle invalidation
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* - We use xattrs to store metadata
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* - We need to be able to query the amount of space available
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* - We want to be able to sync the filesystem when stopping the cache
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* - We use DIO to/from pages, so the blocksize mustn't be too big.
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*/
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ret = -EOPNOTSUPP;
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if (d_is_negative(root) ||
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!d_backing_inode(root)->i_op->lookup ||
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!d_backing_inode(root)->i_op->mkdir ||
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!d_backing_inode(root)->i_op->tmpfile ||
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!(d_backing_inode(root)->i_opflags & IOP_XATTR) ||
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!root->d_sb->s_op->statfs ||
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!root->d_sb->s_op->sync_fs ||
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root->d_sb->s_blocksize > PAGE_SIZE)
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goto error_unsupported;
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ret = -EROFS;
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if (sb_rdonly(root->d_sb))
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goto error_unsupported;
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/* determine the security of the on-disk cache as this governs
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* security ID of files we create */
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ret = cachefiles_determine_cache_security(cache, root, &saved_cred);
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if (ret < 0)
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goto error_unsupported;
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/* get the cache size and blocksize */
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ret = vfs_statfs(&path, &stats);
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if (ret < 0)
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goto error_unsupported;
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ret = -ERANGE;
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if (stats.f_bsize <= 0)
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goto error_unsupported;
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ret = -EOPNOTSUPP;
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if (stats.f_bsize > PAGE_SIZE)
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goto error_unsupported;
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cache->bsize = stats.f_bsize;
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cache->bshift = ilog2(stats.f_bsize);
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_debug("blksize %u (shift %u)",
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cache->bsize, cache->bshift);
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_debug("size %llu, avail %llu",
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(unsigned long long) stats.f_blocks,
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(unsigned long long) stats.f_bavail);
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/* set up caching limits */
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do_div(stats.f_files, 100);
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cache->fstop = stats.f_files * cache->fstop_percent;
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cache->fcull = stats.f_files * cache->fcull_percent;
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cache->frun = stats.f_files * cache->frun_percent;
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_debug("limits {%llu,%llu,%llu} files",
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(unsigned long long) cache->frun,
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(unsigned long long) cache->fcull,
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(unsigned long long) cache->fstop);
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do_div(stats.f_blocks, 100);
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cache->bstop = stats.f_blocks * cache->bstop_percent;
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cache->bcull = stats.f_blocks * cache->bcull_percent;
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cache->brun = stats.f_blocks * cache->brun_percent;
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_debug("limits {%llu,%llu,%llu} blocks",
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(unsigned long long) cache->brun,
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(unsigned long long) cache->bcull,
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(unsigned long long) cache->bstop);
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/* get the cache directory and check its type */
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cachedir = cachefiles_get_directory(cache, root, "cache", NULL);
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if (IS_ERR(cachedir)) {
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ret = PTR_ERR(cachedir);
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goto error_unsupported;
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}
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cache->store = cachedir;
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/* get the graveyard directory */
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graveyard = cachefiles_get_directory(cache, root, "graveyard", NULL);
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if (IS_ERR(graveyard)) {
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ret = PTR_ERR(graveyard);
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goto error_unsupported;
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}
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cache->graveyard = graveyard;
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cache->cache = cache_cookie;
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ret = fscache_add_cache(cache_cookie, &cachefiles_cache_ops, cache);
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if (ret < 0)
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goto error_add_cache;
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/* done */
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set_bit(CACHEFILES_READY, &cache->flags);
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dput(root);
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pr_info("File cache on %s registered\n", cache_cookie->name);
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/* check how much space the cache has */
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cachefiles_has_space(cache, 0, 0, cachefiles_has_space_check);
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cachefiles_end_secure(cache, saved_cred);
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_leave(" = 0 [%px]", cache->cache);
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return 0;
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error_add_cache:
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cachefiles_put_directory(cache->graveyard);
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cache->graveyard = NULL;
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error_unsupported:
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cachefiles_put_directory(cache->store);
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cache->store = NULL;
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mntput(cache->mnt);
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cache->mnt = NULL;
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dput(root);
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error_open_root:
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cachefiles_end_secure(cache, saved_cred);
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error_getsec:
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fscache_relinquish_cache(cache_cookie);
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cache->cache = NULL;
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pr_err("Failed to register: %d\n", ret);
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return ret;
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}
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/*
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* See if we have space for a number of pages and/or a number of files in the
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* cache
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*/
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int cachefiles_has_space(struct cachefiles_cache *cache,
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unsigned fnr, unsigned bnr,
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enum cachefiles_has_space_for reason)
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{
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struct kstatfs stats;
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u64 b_avail, b_writing;
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int ret;
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struct path path = {
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.mnt = cache->mnt,
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.dentry = cache->mnt->mnt_root,
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};
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//_enter("{%llu,%llu,%llu,%llu,%llu,%llu},%u,%u",
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// (unsigned long long) cache->frun,
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// (unsigned long long) cache->fcull,
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// (unsigned long long) cache->fstop,
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// (unsigned long long) cache->brun,
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// (unsigned long long) cache->bcull,
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// (unsigned long long) cache->bstop,
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// fnr, bnr);
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/* find out how many pages of blockdev are available */
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memset(&stats, 0, sizeof(stats));
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ret = vfs_statfs(&path, &stats);
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if (ret < 0) {
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trace_cachefiles_vfs_error(NULL, d_inode(path.dentry), ret,
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cachefiles_trace_statfs_error);
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if (ret == -EIO)
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cachefiles_io_error(cache, "statfs failed");
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_leave(" = %d", ret);
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return ret;
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}
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b_avail = stats.f_bavail;
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b_writing = atomic_long_read(&cache->b_writing);
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if (b_avail > b_writing)
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b_avail -= b_writing;
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else
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b_avail = 0;
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//_debug("avail %llu,%llu",
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// (unsigned long long)stats.f_ffree,
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// (unsigned long long)b_avail);
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/* see if there is sufficient space */
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if (stats.f_ffree > fnr)
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stats.f_ffree -= fnr;
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else
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stats.f_ffree = 0;
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if (b_avail > bnr)
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b_avail -= bnr;
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else
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b_avail = 0;
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ret = -ENOBUFS;
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if (stats.f_ffree < cache->fstop ||
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b_avail < cache->bstop)
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goto stop_and_begin_cull;
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ret = 0;
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if (stats.f_ffree < cache->fcull ||
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b_avail < cache->bcull)
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goto begin_cull;
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if (test_bit(CACHEFILES_CULLING, &cache->flags) &&
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stats.f_ffree >= cache->frun &&
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b_avail >= cache->brun &&
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test_and_clear_bit(CACHEFILES_CULLING, &cache->flags)
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) {
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_debug("cease culling");
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cachefiles_state_changed(cache);
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}
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//_leave(" = 0");
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return 0;
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stop_and_begin_cull:
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switch (reason) {
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case cachefiles_has_space_for_write:
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fscache_count_no_write_space();
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break;
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case cachefiles_has_space_for_create:
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fscache_count_no_create_space();
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break;
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default:
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break;
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}
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begin_cull:
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if (!test_and_set_bit(CACHEFILES_CULLING, &cache->flags)) {
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_debug("### CULL CACHE ###");
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cachefiles_state_changed(cache);
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}
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_leave(" = %d", ret);
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return ret;
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}
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/*
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* Mark all the objects as being out of service and queue them all for cleanup.
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*/
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static void cachefiles_withdraw_objects(struct cachefiles_cache *cache)
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{
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struct cachefiles_object *object;
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unsigned int count = 0;
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_enter("");
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spin_lock(&cache->object_list_lock);
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while (!list_empty(&cache->object_list)) {
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object = list_first_entry(&cache->object_list,
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struct cachefiles_object, cache_link);
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cachefiles_see_object(object, cachefiles_obj_see_withdrawal);
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list_del_init(&object->cache_link);
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fscache_withdraw_cookie(object->cookie);
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count++;
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if ((count & 63) == 0) {
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spin_unlock(&cache->object_list_lock);
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cond_resched();
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spin_lock(&cache->object_list_lock);
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}
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}
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spin_unlock(&cache->object_list_lock);
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_leave(" [%u objs]", count);
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}
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/*
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* Withdraw volumes.
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*/
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static void cachefiles_withdraw_volumes(struct cachefiles_cache *cache)
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{
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_enter("");
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for (;;) {
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struct cachefiles_volume *volume = NULL;
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spin_lock(&cache->object_list_lock);
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if (!list_empty(&cache->volumes)) {
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volume = list_first_entry(&cache->volumes,
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struct cachefiles_volume, cache_link);
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list_del_init(&volume->cache_link);
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}
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spin_unlock(&cache->object_list_lock);
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if (!volume)
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break;
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cachefiles_withdraw_volume(volume);
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}
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_leave("");
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}
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/*
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* Sync a cache to backing disk.
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*/
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static void cachefiles_sync_cache(struct cachefiles_cache *cache)
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{
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const struct cred *saved_cred;
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int ret;
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_enter("%s", cache->cache->name);
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/* make sure all pages pinned by operations on behalf of the netfs are
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* written to disc */
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cachefiles_begin_secure(cache, &saved_cred);
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down_read(&cache->mnt->mnt_sb->s_umount);
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ret = sync_filesystem(cache->mnt->mnt_sb);
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up_read(&cache->mnt->mnt_sb->s_umount);
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cachefiles_end_secure(cache, saved_cred);
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if (ret == -EIO)
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cachefiles_io_error(cache,
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"Attempt to sync backing fs superblock returned error %d",
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ret);
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}
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/*
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* Withdraw cache objects.
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*/
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void cachefiles_withdraw_cache(struct cachefiles_cache *cache)
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{
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struct fscache_cache *fscache = cache->cache;
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pr_info("File cache on %s unregistering\n", fscache->name);
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fscache_withdraw_cache(fscache);
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/* we now have to destroy all the active objects pertaining to this
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* cache - which we do by passing them off to thread pool to be
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* disposed of */
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cachefiles_withdraw_objects(cache);
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fscache_wait_for_objects(fscache);
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cachefiles_withdraw_volumes(cache);
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cachefiles_sync_cache(cache);
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cache->cache = NULL;
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fscache_relinquish_cache(fscache);
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}
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