fs/cachefiles/volume.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* Volume handling.
   3  *
   4  * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  */
   7
   8 #include <linux/fs.h>
   9 #include <linux/slab.h>
  10 #include "internal.h"
  11 #include <trace/events/fscache.h>
  12
  13 /*
  14  * Allocate and set up a volume representation.  We make sure all the fanout
  15  * directories are created and pinned.
  16  */
  17 void cachefiles_acquire_volume(struct fscache_volume *vcookie)
  18 {
  19         struct cachefiles_volume *volume;
  20         struct cachefiles_cache *cache = vcookie->cache->cache_priv;
  21         const struct cred *saved_cred;
  22         struct dentry *vdentry, *fan;
  23         size_t len;
  24         char *name;
  25         bool is_new = false;
  26         int ret, n_accesses, i;
  27
  28         _enter("");
  29
  30         volume = kzalloc(sizeof(struct cachefiles_volume), GFP_KERNEL);
  31         if (!volume)
  32                 return;
  33         volume->vcookie = vcookie;
  34         volume->cache = cache;
  35         INIT_LIST_HEAD(&volume->cache_link);
  36
  37         cachefiles_begin_secure(cache, &saved_cred);
  38
  39         len = vcookie->key[0];
  40         name = kmalloc(len + 3, GFP_NOFS);
  41         if (!name)
  42                 goto error_vol;
  43         name[0] = 'I';
  44         memcpy(name + 1, vcookie->key + 1, len);
  45         name[len + 1] = 0;
  46
  47 retry:
  48         vdentry = cachefiles_get_directory(cache, cache->store, name, &is_new);
  49         if (IS_ERR(vdentry))
  50                 goto error_name;
  51         volume->dentry = vdentry;
  52
  53         if (is_new) {
  54                 if (!cachefiles_set_volume_xattr(volume))
  55                         goto error_dir;
  56         } else {
  57                 ret = cachefiles_check_volume_xattr(volume);
  58                 if (ret < 0) {
  59                         if (ret != -ESTALE)
  60                                 goto error_dir;
  61                         inode_lock_nested(d_inode(cache->store), I_MUTEX_PARENT);
  62                         cachefiles_bury_object(cache, NULL, cache->store, vdentry,
  63                                                FSCACHE_VOLUME_IS_WEIRD);
  64                         cachefiles_put_directory(volume->dentry);
  65                         cond_resched();
  66                         goto retry;
  67                 }
  68         }
  69
  70         for (i = 0; i < 256; i++) {
  71                 sprintf(name, "@%02x", i);
  72                 fan = cachefiles_get_directory(cache, vdentry, name, NULL);
  73                 if (IS_ERR(fan))
  74                         goto error_fan;
  75                 volume->fanout[i] = fan;
  76         }
  77
  78         cachefiles_end_secure(cache, saved_cred);
  79
  80         vcookie->cache_priv = volume;
  81         n_accesses = atomic_inc_return(&vcookie->n_accesses); /* Stop wakeups on dec-to-0 */
  82         trace_fscache_access_volume(vcookie->debug_id, 0,
  83                                     refcount_read(&vcookie->ref),
  84                                     n_accesses, fscache_access_cache_pin);
  85
  86         spin_lock(&cache->object_list_lock);
  87         list_add(&volume->cache_link, &volume->cache->volumes);
  88         spin_unlock(&cache->object_list_lock);
  89
  90         kfree(name);
  91         return;
  92
  93 error_fan:
  94         for (i = 0; i < 256; i++)
  95                 cachefiles_put_directory(volume->fanout[i]);
  96 error_dir:
  97         cachefiles_put_directory(volume->dentry);
  98 error_name:
  99         kfree(name);
 100 error_vol:
 101         kfree(volume);
 102         cachefiles_end_secure(cache, saved_cred);
 103 }
 104
 105 /*
 106  * Release a volume representation.
 107  */
 108 static void __cachefiles_free_volume(struct cachefiles_volume *volume)
 109 {
 110         int i;
 111
 112         _enter("");
 113
 114         volume->vcookie->cache_priv = NULL;
 115
 116         for (i = 0; i < 256; i++)
 117                 cachefiles_put_directory(volume->fanout[i]);
 118         cachefiles_put_directory(volume->dentry);
 119         kfree(volume);
 120 }
 121
 122 void cachefiles_free_volume(struct fscache_volume *vcookie)
 123 {
 124         struct cachefiles_volume *volume = vcookie->cache_priv;
 125
 126         if (volume) {
 127                 spin_lock(&volume->cache->object_list_lock);
 128                 list_del_init(&volume->cache_link);
 129                 spin_unlock(&volume->cache->object_list_lock);
 130                 __cachefiles_free_volume(volume);
 131         }
 132 }
 133
 134 void cachefiles_withdraw_volume(struct cachefiles_volume *volume)
 135 {
 136         fscache_withdraw_volume(volume->vcookie);
 137         cachefiles_set_volume_xattr(volume);
 138         __cachefiles_free_volume(volume);
 139 }