fs/btrfs/sysfs.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/sched.h>
  20 #include <linux/slab.h>
  21 #include <linux/spinlock.h>
  22 #include <linux/completion.h>
  23 #include <linux/buffer_head.h>
  24 #include <linux/kobject.h>
  25
  26 #include "ctree.h"
  27 #include "disk-io.h"
  28 #include "transaction.h"
  29 #include "sysfs.h"
  30
  31 static inline struct btrfs_fs_info *to_fs_info(struct kobject *kobj);
  32
  33 static u64 get_features(struct btrfs_fs_info *fs_info,
  34                         enum btrfs_feature_set set)
  35 {
  36         struct btrfs_super_block *disk_super = fs_info->super_copy;
  37         if (set == FEAT_COMPAT)
  38                 return btrfs_super_compat_flags(disk_super);
  39         else if (set == FEAT_COMPAT_RO)
  40                 return btrfs_super_compat_ro_flags(disk_super);
  41         else
  42                 return btrfs_super_incompat_flags(disk_super);
  43 }
  44
  45 static ssize_t btrfs_feature_attr_show(struct kobject *kobj,
  46                                        struct kobj_attribute *a, char *buf)
  47 {
  48         int val = 0;
  49         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
  50         if (fs_info) {
  51                 struct btrfs_feature_attr *fa = to_btrfs_feature_attr(a);
  52                 u64 features = get_features(fs_info, fa->feature_set);
  53                 if (features & fa->feature_bit)
  54                         val = 1;
  55         }
  56
  57         return snprintf(buf, PAGE_SIZE, "%d\n", val);
  58 }
  59
  60 static umode_t btrfs_feature_visible(struct kobject *kobj,
  61                                      struct attribute *attr, int unused)
  62 {
  63         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
  64         umode_t mode = attr->mode;
  65
  66         if (fs_info) {
  67                 struct btrfs_feature_attr *fa;
  68                 u64 features;
  69
  70                 fa = attr_to_btrfs_feature_attr(attr);
  71                 features = get_features(fs_info, fa->feature_set);
  72
  73                 if (!(features & fa->feature_bit))
  74                         mode = 0;
  75         }
  76
  77         return mode;
  78 }
  79
  80 BTRFS_FEAT_ATTR_INCOMPAT(mixed_backref, MIXED_BACKREF);
  81 BTRFS_FEAT_ATTR_INCOMPAT(default_subvol, DEFAULT_SUBVOL);
  82 BTRFS_FEAT_ATTR_INCOMPAT(mixed_groups, MIXED_GROUPS);
  83 BTRFS_FEAT_ATTR_INCOMPAT(compress_lzo, COMPRESS_LZO);
  84 BTRFS_FEAT_ATTR_INCOMPAT(compress_lzov2, COMPRESS_LZOv2);
  85 BTRFS_FEAT_ATTR_INCOMPAT(big_metadata, BIG_METADATA);
  86 BTRFS_FEAT_ATTR_INCOMPAT(extended_iref, EXTENDED_IREF);
  87 BTRFS_FEAT_ATTR_INCOMPAT(raid56, RAID56);
  88 BTRFS_FEAT_ATTR_INCOMPAT(skinny_metadata, SKINNY_METADATA);
  89
  90 static struct attribute *btrfs_supported_feature_attrs[] = {
  91         BTRFS_FEAT_ATTR_PTR(mixed_backref),
  92         BTRFS_FEAT_ATTR_PTR(default_subvol),
  93         BTRFS_FEAT_ATTR_PTR(mixed_groups),
  94         BTRFS_FEAT_ATTR_PTR(compress_lzo),
  95         BTRFS_FEAT_ATTR_PTR(compress_lzov2),
  96         BTRFS_FEAT_ATTR_PTR(big_metadata),
  97         BTRFS_FEAT_ATTR_PTR(extended_iref),
  98         BTRFS_FEAT_ATTR_PTR(raid56),
  99         BTRFS_FEAT_ATTR_PTR(skinny_metadata),
 100         NULL
 101 };
 102
 103 static const struct attribute_group btrfs_feature_attr_group = {
 104         .name = "features",
 105         .is_visible = btrfs_feature_visible,
 106         .attrs = btrfs_supported_feature_attrs,
 107 };
 108
 109 static void btrfs_release_super_kobj(struct kobject *kobj)
 110 {
 111         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 112         complete(&fs_info->kobj_unregister);
 113 }
 114
 115 static struct kobj_type btrfs_ktype = {
 116         .sysfs_ops      = &kobj_sysfs_ops,
 117         .release        = btrfs_release_super_kobj,
 118 };
 119
 120 static inline struct btrfs_fs_info *to_fs_info(struct kobject *kobj)
 121 {
 122         if (kobj->ktype != &btrfs_ktype)
 123                 return NULL;
 124         return container_of(kobj, struct btrfs_fs_info, super_kobj);
 125 }
 126
 127 void btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info)
 128 {
 129         kobject_del(&fs_info->super_kobj);
 130         kobject_put(&fs_info->super_kobj);
 131         wait_for_completion(&fs_info->kobj_unregister);
 132 }
 133
 134 /* /sys/fs/btrfs/ entry */
 135 static struct kset *btrfs_kset;
 136
 137 int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info)
 138 {
 139         int error;
 140
 141         init_completion(&fs_info->kobj_unregister);
 142         fs_info->super_kobj.kset = btrfs_kset;
 143         error = kobject_init_and_add(&fs_info->super_kobj, &btrfs_ktype, NULL,
 144                                      "%pU", fs_info->fsid);
 145
 146         error = sysfs_create_group(&fs_info->super_kobj,
 147                                    &btrfs_feature_attr_group);
 148         if (error)
 149                 btrfs_sysfs_remove_one(fs_info);
 150         return error;
 151 }
 152
 153 int btrfs_init_sysfs(void)
 154 {
 155         int ret;
 156         btrfs_kset = kset_create_and_add("btrfs", NULL, fs_kobj);
 157         if (!btrfs_kset)
 158                 return -ENOMEM;
 159
 160         ret = sysfs_create_group(&btrfs_kset->kobj, &btrfs_feature_attr_group);
 161         if (ret) {
 162                 kset_unregister(btrfs_kset);
 163                 return ret;
 164         }
 165
 166         return 0;
 167 }
 168
 169 void btrfs_exit_sysfs(void)
 170 {
 171         sysfs_remove_group(&btrfs_kset->kobj, &btrfs_feature_attr_group);
 172         kset_unregister(btrfs_kset);
 173 }
 174