1 From aa88a112a579b0122e62eff87d581fcca11ad805 Mon Sep 17 00:00:00 2001
2 From: Erez Zadok <ezk@fsl.cs.sunysb.edu>
3 Date: Mon, 23 May 2011 20:59:20 -0400
4 Subject: [PATCH 06/13] overlayfs: implement show_options
5 Patch-mainline: not yet
7 This is useful because of the stacking nature of overlayfs. Users like to
8 find out (via /proc/mounts) which lower/upper directory were used at mount
11 Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
12 Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
14 fs/overlayfs/super.c | 63 ++++++++++++++++++++++++++++++++++-----------------
15 1 file changed, 43 insertions(+), 20 deletions(-)
17 --- a/fs/overlayfs/super.c
18 +++ b/fs/overlayfs/super.c
20 #include <linux/cred.h>
21 #include <linux/sched.h>
22 #include <linux/statfs.h>
23 +#include <linux/seq_file.h>
24 #include "overlayfs.h"
26 MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
27 @@ -26,12 +27,21 @@ MODULE_LICENSE("GPL");
29 #define OVERLAYFS_SUPER_MAGIC 0x794c764f
36 +/* private information held for overlayfs's superblock */
38 struct vfsmount *upper_mnt;
39 struct vfsmount *lower_mnt;
41 + /* pathnames of lower and upper dirs, for show_options */
42 + struct ovl_config config;
45 +/* private information held for every overlayfs dentry */
48 * Keep "double reference" on upper dentries, so that
49 @@ -389,6 +399,8 @@ static void ovl_put_super(struct super_b
50 mntput(ufs->upper_mnt);
51 mntput(ufs->lower_mnt);
53 + kfree(ufs->config.lowerdir);
54 + kfree(ufs->config.upperdir);
58 @@ -437,15 +449,27 @@ static int ovl_statfs(struct dentry *den
65 + * Prints the mount options for a given superblock.
66 + * Returns zero; does not fail.
68 +static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
70 + struct super_block *sb = dentry->d_sb;
71 + struct ovl_fs *ufs = sb->s_fs_info;
73 + seq_printf(m, ",lowerdir=%s", ufs->config.lowerdir);
74 + seq_printf(m, ",upperdir=%s", ufs->config.upperdir);
78 static const struct super_operations ovl_super_operations = {
79 .put_super = ovl_put_super,
80 .remount_fs = ovl_remount_fs,
87 + .show_options = ovl_show_options,
91 @@ -505,34 +529,33 @@ static int ovl_fill_super(struct super_b
92 struct dentry *root_dentry;
95 - struct ovl_config config;
96 struct kstatfs statfs;
99 - err = ovl_parse_opt((char *) data, &config);
102 + ufs = kmalloc(sizeof(struct ovl_fs), GFP_KERNEL);
106 + err = ovl_parse_opt((char *) data, &ufs->config);
111 - if (!config.upperdir || !config.lowerdir) {
112 + if (!ufs->config.upperdir || !ufs->config.lowerdir) {
113 pr_err("overlayfs: missing upperdir or lowerdir\n");
114 goto out_free_config;
118 - ufs = kmalloc(sizeof(struct ovl_fs), GFP_KERNEL);
120 - goto out_free_config;
122 oe = ovl_alloc_entry();
125 + goto out_free_config;
127 - err = kern_path(config.upperdir, LOOKUP_FOLLOW, &upperpath);
128 + err = kern_path(ufs->config.upperdir, LOOKUP_FOLLOW, &upperpath);
132 - err = kern_path(config.lowerdir, LOOKUP_FOLLOW, &lowerpath);
133 + err = kern_path(ufs->config.lowerdir, LOOKUP_FOLLOW, &lowerpath);
135 goto out_put_upperpath;
137 @@ -616,11 +639,11 @@ static int ovl_fill_super(struct super_b
138 path_put(&upperpath);
142 + kfree(ufs->config.lowerdir);
143 + kfree(ufs->config.upperdir);
147 - kfree(config.lowerdir);
148 - kfree(config.upperdir);