104 lines
2.4 KiB
C
104 lines
2.4 KiB
C
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// 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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* 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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{
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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 >> cache->bshift;
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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 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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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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