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-rw-r--r--fs/overlayfs/super.c40
1 files changed, 40 insertions, 0 deletions
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 227710aad781..aaf562b9f937 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -16,17 +16,21 @@
#include <linux/parser.h>
#include <linux/module.h>
#include <linux/sched.h>
+#include <linux/statfs.h>
#include "overlayfs.h"
MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
MODULE_DESCRIPTION("Overlay filesystem");
MODULE_LICENSE("GPL");
+#define OVERLAYFS_SUPER_MAGIC 0x794c764f
+
/* private information held for overlayfs's superblock */
struct ovl_fs {
struct vfsmount *upper_mnt;
struct vfsmount *lower_mnt;
struct dentry *workdir;
+ long lower_namelen;
};
struct ovl_dir_cache;
@@ -383,8 +387,35 @@ static void ovl_put_super(struct super_block *sb)
kfree(ufs);
}
+/**
+ * ovl_statfs
+ * @sb: The overlayfs super block
+ * @buf: The struct kstatfs to fill in with stats
+ *
+ * Get the filesystem statistics. As writes always target the upper layer
+ * filesystem pass the statfs to the same filesystem.
+ */
+static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+ struct dentry *root_dentry = dentry->d_sb->s_root;
+ struct path path;
+ int err;
+
+ ovl_path_upper(root_dentry, &path);
+
+ err = vfs_statfs(&path, buf);
+ if (!err) {
+ buf->f_namelen = max(buf->f_namelen, ofs->lower_namelen);
+ buf->f_type = OVERLAYFS_SUPER_MAGIC;
+ }
+
+ return err;
+}
+
static const struct super_operations ovl_super_operations = {
.put_super = ovl_put_super,
+ .statfs = ovl_statfs,
};
struct ovl_config {
@@ -556,6 +587,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
struct ovl_entry *oe;
struct ovl_fs *ufs;
struct ovl_config config;
+ struct kstatfs statfs;
int err;
err = ovl_parse_opt((char *) data, &config);
@@ -617,6 +649,13 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
goto out_put_workpath;
}
+ err = vfs_statfs(&lowerpath, &statfs);
+ if (err) {
+ pr_err("overlayfs: statfs failed on lowerpath\n");
+ goto out_put_workpath;
+ }
+ ufs->lower_namelen = statfs.f_namelen;
+
ufs->upper_mnt = clone_private_mount(&upperpath);
err = PTR_ERR(ufs->upper_mnt);
if (IS_ERR(ufs->upper_mnt)) {
@@ -669,6 +708,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
root_dentry->d_fsdata = oe;
+ sb->s_magic = OVERLAYFS_SUPER_MAGIC;
sb->s_op = &ovl_super_operations;
sb->s_root = root_dentry;
sb->s_fs_info = ufs;