From 80f94f29f677d32a1edabc055acfe91c00803592 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 21 Oct 2021 08:59:46 +0100 Subject: cachefiles: Provide a function to check how much space there is Provide a function to check how much space there is. This also flips the state on the cache and will signal the daemon to inform it of the change and to ask it to do some culling if necessary. We will also need to subtract the amount of data currently being written to the cache (cache->b_writing) from the amount of available space to avoid hitting ENOSPC accidentally. Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/163819629322.215744.13457425294680841213.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906930100.143852.1681026700865762069.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163967140058.1823006.7781243664702837128.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/164021539957.640689.12477177372616805706.stgit@warthog.procyon.org.uk/ # v4 --- fs/cachefiles/cache.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 103 insertions(+) create mode 100644 fs/cachefiles/cache.c (limited to 'fs/cachefiles/cache.c') diff --git a/fs/cachefiles/cache.c b/fs/cachefiles/cache.c new file mode 100644 index 000000000000..73636f89eefa --- /dev/null +++ b/fs/cachefiles/cache.c @@ -0,0 +1,103 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* Manage high-level VFS aspects of a cache. + * + * Copyright (C) 2007, 2021 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include +#include +#include +#include "internal.h" + +/* + * See if we have space for a number of pages and/or a number of files in the + * cache + */ +int cachefiles_has_space(struct cachefiles_cache *cache, + unsigned fnr, unsigned bnr) +{ + struct kstatfs stats; + u64 b_avail, b_writing; + int ret; + + struct path path = { + .mnt = cache->mnt, + .dentry = cache->mnt->mnt_root, + }; + + //_enter("{%llu,%llu,%llu,%llu,%llu,%llu},%u,%u", + // (unsigned long long) cache->frun, + // (unsigned long long) cache->fcull, + // (unsigned long long) cache->fstop, + // (unsigned long long) cache->brun, + // (unsigned long long) cache->bcull, + // (unsigned long long) cache->bstop, + // fnr, bnr); + + /* find out how many pages of blockdev are available */ + memset(&stats, 0, sizeof(stats)); + + ret = vfs_statfs(&path, &stats); + if (ret < 0) { + trace_cachefiles_vfs_error(NULL, d_inode(path.dentry), ret, + cachefiles_trace_statfs_error); + if (ret == -EIO) + cachefiles_io_error(cache, "statfs failed"); + _leave(" = %d", ret); + return ret; + } + + b_avail = stats.f_bavail >> cache->bshift; + b_writing = atomic_long_read(&cache->b_writing); + if (b_avail > b_writing) + b_avail -= b_writing; + else + b_avail = 0; + + //_debug("avail %llu,%llu", + // (unsigned long long)stats.f_ffree, + // (unsigned long long)b_avail); + + /* see if there is sufficient space */ + if (stats.f_ffree > fnr) + stats.f_ffree -= fnr; + else + stats.f_ffree = 0; + + if (b_avail > bnr) + b_avail -= bnr; + else + b_avail = 0; + + ret = -ENOBUFS; + if (stats.f_ffree < cache->fstop || + b_avail < cache->bstop) + goto begin_cull; + + ret = 0; + if (stats.f_ffree < cache->fcull || + b_avail < cache->bcull) + goto begin_cull; + + if (test_bit(CACHEFILES_CULLING, &cache->flags) && + stats.f_ffree >= cache->frun && + b_avail >= cache->brun && + test_and_clear_bit(CACHEFILES_CULLING, &cache->flags) + ) { + _debug("cease culling"); + cachefiles_state_changed(cache); + } + + //_leave(" = 0"); + return 0; + +begin_cull: + if (!test_and_set_bit(CACHEFILES_CULLING, &cache->flags)) { + _debug("### CULL CACHE ###"); + cachefiles_state_changed(cache); + } + + _leave(" = %d", ret); + return ret; +} -- cgit v1.2.3