156 lines
3.9 KiB
Diff
156 lines
3.9 KiB
Diff
From 4ff99cccd67514e258c97d71593ba495e1b2a89f Mon Sep 17 00:00:00 2001
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From: Erez Zadok <ezk@fsl.cs.sunysb.edu>
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Date: Thu, 27 Jun 2013 16:39:50 +0200
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Subject: [PATCH 7/9] overlayfs: implement show_options
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This is useful because of the stacking nature of overlayfs. Users like to
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find out (via /proc/mounts) which lower/upper directory were used at mount
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time.
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Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
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Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
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---
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fs/overlayfs/super.c | 63 +++++++++++++++++++++++++++++++++++-----------------
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1 file changed, 43 insertions(+), 20 deletions(-)
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diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
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index a9970b5..066ea5a 100644
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--- a/fs/overlayfs/super.c
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+++ b/fs/overlayfs/super.c
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@@ -18,6 +18,7 @@
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#include <linux/cred.h>
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#include <linux/sched.h>
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#include <linux/statfs.h>
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+#include <linux/seq_file.h>
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#include "overlayfs.h"
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MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
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@@ -26,12 +27,21 @@ MODULE_LICENSE("GPL");
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#define OVERLAYFS_SUPER_MAGIC 0x794c764f
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+struct ovl_config {
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+ char *lowerdir;
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+ char *upperdir;
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+};
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+
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+/* private information held for overlayfs's superblock */
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struct ovl_fs {
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struct vfsmount *upper_mnt;
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struct vfsmount *lower_mnt;
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long lower_namelen;
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+ /* pathnames of lower and upper dirs, for show_options */
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+ struct ovl_config config;
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};
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+/* private information held for every overlayfs dentry */
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struct ovl_entry {
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/*
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* Keep "double reference" on upper dentries, so that
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@@ -388,6 +398,8 @@ static void ovl_put_super(struct super_block *sb)
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mntput(ufs->upper_mnt);
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mntput(ufs->lower_mnt);
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+ kfree(ufs->config.lowerdir);
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+ kfree(ufs->config.upperdir);
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kfree(ufs);
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}
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@@ -436,15 +448,27 @@ static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
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return err;
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}
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+/**
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+ * ovl_show_options
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+ *
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+ * Prints the mount options for a given superblock.
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+ * Returns zero; does not fail.
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+ */
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+static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
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+{
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+ struct super_block *sb = dentry->d_sb;
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+ struct ovl_fs *ufs = sb->s_fs_info;
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+
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+ seq_printf(m, ",lowerdir=%s", ufs->config.lowerdir);
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+ seq_printf(m, ",upperdir=%s", ufs->config.upperdir);
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+ return 0;
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+}
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+
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static const struct super_operations ovl_super_operations = {
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.put_super = ovl_put_super,
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.remount_fs = ovl_remount_fs,
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.statfs = ovl_statfs,
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-};
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-
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-struct ovl_config {
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- char *lowerdir;
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- char *upperdir;
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+ .show_options = ovl_show_options,
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};
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enum {
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@@ -504,34 +528,33 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
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struct dentry *root_dentry;
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struct ovl_entry *oe;
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struct ovl_fs *ufs;
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- struct ovl_config config;
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struct kstatfs statfs;
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int err;
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- err = ovl_parse_opt((char *) data, &config);
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- if (err)
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+ err = -ENOMEM;
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+ ufs = kmalloc(sizeof(struct ovl_fs), GFP_KERNEL);
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+ if (!ufs)
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goto out;
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+ err = ovl_parse_opt((char *) data, &ufs->config);
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+ if (err)
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+ goto out_free_ufs;
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+
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err = -EINVAL;
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- if (!config.upperdir || !config.lowerdir) {
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+ if (!ufs->config.upperdir || !ufs->config.lowerdir) {
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pr_err("overlayfs: missing upperdir or lowerdir\n");
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goto out_free_config;
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}
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- err = -ENOMEM;
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- ufs = kmalloc(sizeof(struct ovl_fs), GFP_KERNEL);
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- if (!ufs)
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- goto out_free_config;
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-
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oe = ovl_alloc_entry();
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if (oe == NULL)
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- goto out_free_ufs;
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+ goto out_free_config;
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- err = kern_path(config.upperdir, LOOKUP_FOLLOW, &upperpath);
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+ err = kern_path(ufs->config.upperdir, LOOKUP_FOLLOW, &upperpath);
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if (err)
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goto out_free_oe;
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- err = kern_path(config.lowerdir, LOOKUP_FOLLOW, &lowerpath);
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+ err = kern_path(ufs->config.lowerdir, LOOKUP_FOLLOW, &lowerpath);
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if (err)
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goto out_put_upperpath;
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@@ -615,11 +638,11 @@ out_put_upperpath:
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path_put(&upperpath);
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out_free_oe:
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kfree(oe);
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+out_free_config:
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+ kfree(ufs->config.lowerdir);
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+ kfree(ufs->config.upperdir);
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out_free_ufs:
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kfree(ufs);
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-out_free_config:
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- kfree(config.lowerdir);
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- kfree(config.upperdir);
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out:
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return err;
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}
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--
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1.8.3.2
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