In order to expose tmpfs statistics on sysfs, add the boilerplate code
to create the /sys/fs/tmpfs structure. As suggested on a previous
review, this uses the minor as the volume directory in /sys/fs/.
This takes care of not exposing SB_NOUSER mounts. I don't think we have
a usecase for showing them and, since they don't appear elsewhere, they
might be confusing to users.
Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
---
Changes since v1:
- Use minor instead of fsid for directory in sysfs. (Amir)
---
include/linux/shmem_fs.h | 4 +++
mm/shmem.c | 72 +++++++++++++++++++++++++++++++++++++++-
2 files changed, 75 insertions(+), 1 deletion(-)
diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index 1a7cd9ea9107..c27ecf0e1b3b 100644
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -47,6 +47,10 @@ struct shmem_sb_info {
unsigned long acct_errors;
unsigned long space_errors;
+
+ /* sysfs */
+ struct kobject s_kobj; /* /sys/fs/tmpfs/<uuid> */
+ struct completion s_kobj_unregister;
};
static inline struct shmem_inode_info *SHMEM_I(struct inode *inode)
diff --git a/mm/shmem.c b/mm/shmem.c
index c350fa0a0fff..665d417ba8a8 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -250,6 +250,7 @@ static const struct inode_operations shmem_dir_inode_operations;
static const struct inode_operations shmem_special_inode_operations;
static const struct vm_operations_struct shmem_vm_ops;
static struct file_system_type shmem_fs_type;
+static struct kobject *shmem_root;
bool vma_is_shmem(struct vm_area_struct *vma)
{
@@ -3584,6 +3585,56 @@ static int shmem_show_options(struct seq_file *seq, struct dentry *root)
#endif /* CONFIG_TMPFS */
+#if defined(CONFIG_TMPFS) && defined(CONFIG_SYSFS)
+#define TMPFS_SB_ATTR_RO(name) \
+ static struct kobj_attribute tmpfs_sb_attr_##name = __ATTR_RO(name)
+
+static struct attribute *tmpfs_attrs[] = {
+ NULL
+};
+ATTRIBUTE_GROUPS(tmpfs);
+
+static void tmpfs_sb_release(struct kobject *kobj)
+{
+ struct shmem_sb_info *sbinfo =
+ container_of(kobj, struct shmem_sb_info, s_kobj);
+
+ complete(&sbinfo->s_kobj_unregister);
+}
+
+static struct kobj_type tmpfs_sb_ktype = {
+ .default_groups = tmpfs_groups,
+ .sysfs_ops = &kobj_sysfs_ops,
+ .release = tmpfs_sb_release,
+};
+
+static void shmem_unregister_sysfs(struct super_block *sb)
+{
+ struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
+
+ kobject_del(&sbinfo->s_kobj);
+ kobject_put(&sbinfo->s_kobj);
+ wait_for_completion(&sbinfo->s_kobj_unregister);
+}
+
+static int shmem_register_sysfs(struct super_block *sb)
+{
+ int err;
+ struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
+
+ init_completion(&sbinfo->s_kobj_unregister);
+ err = kobject_init_and_add(&sbinfo->s_kobj, &tmpfs_sb_ktype,
+ shmem_root, "%d", MINOR(sb->s_dev));
+ if (err) {
+ kobject_put(&sbinfo->s_kobj);
+ wait_for_completion(&sbinfo->s_kobj_unregister);
+ return err;
+ }
+
+ return 0;
+}
+#endif /* CONFIG_TMPFS && CONFIG_SYSFS */
+
static void shmem_put_super(struct super_block *sb)
{
struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
@@ -3591,6 +3642,12 @@ static void shmem_put_super(struct super_block *sb)
free_percpu(sbinfo->ino_batch);
percpu_counter_destroy(&sbinfo->used_blocks);
mpol_put(sbinfo->mpol);
+
+#if IS_ENABLED(CONFIG_TMPFS) && IS_ENABLED(CONFIG_SYSFS)
+ if (!(sb->s_flags & SB_NOUSER))
+ shmem_unregister_sysfs(sb);
+#endif
+
kfree(sbinfo);
sb->s_fs_info = NULL;
}
@@ -3673,6 +3730,13 @@ static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
sb->s_root = d_make_root(inode);
if (!sb->s_root)
goto failed;
+
+#if IS_ENABLED(CONFIG_TMPFS) && IS_ENABLED(CONFIG_SYSFS)
+ if (!(sb->s_flags & SB_NOUSER))
+ if (shmem_register_sysfs(sb))
+ goto failed;
+#endif
+
return 0;
failed:
@@ -3889,11 +3953,15 @@ int __init shmem_init(void)
goto out2;
}
+ shmem_root = kobject_create_and_add("tmpfs", fs_kobj);
+ if (!shmem_root)
+ goto out1;
+
shm_mnt = kern_mount(&shmem_fs_type);
if (IS_ERR(shm_mnt)) {
error = PTR_ERR(shm_mnt);
pr_err("Could not kern_mount tmpfs\n");
- goto out1;
+ goto put_kobj;
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
@@ -3904,6 +3972,8 @@ int __init shmem_init(void)
#endif
return 0;
+put_kobj:
+ kobject_put(shmem_root);
out1:
unregister_filesystem(&shmem_fs_type);
out2:
--
2.35.1
