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// 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 <linux/slab.h>
#include <linux/statfs.h>
#include <linux/namei.h>
#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;
}
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