commit c7f404b40a3665d9f4e9a927cc5c1ee0479ed8f9
author Al Viro <viro@zeniv.linux.org.uk> Wed Mar 16 06:59:40 2011 -0400
committer Al Viro <viro@zeniv.linux.org.uk> Wed Mar 16 16:48:06 2011 -0400
tree 2d6fa2bef00efa759f36b17f3be0d4fab3ac9bb5
parent f8ad9c4bae99854c961ca79ed130a0d11d9ab53c

vfs: new superblock methods to override /proc/*/mount{s,info}

a) ->show_devname(m, mnt) - what to put into devname columns in mounts,
mountinfo and mountstats
b) ->show_path(m, mnt) - what to put into relative path column in mountinfo

Leaving those NULL gives old behaviour.  NFS switched to using those.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/namespace.c

diff --git a/fs/namespace.c b/fs/namespace.c
index dffe6f4..75d843a 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -978,7 +978,13 @@
 	int err = 0;
 	struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
 
-	mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
+	if (mnt->mnt_sb->s_op->show_devname) {
+		err = mnt->mnt_sb->s_op->show_devname(m, mnt);
+		if (err)
+			goto out;
+	} else {
+		mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
+	}
 	seq_putc(m, ' ');
 	seq_path(m, &mnt_path, " \t\n\\");
 	seq_putc(m, ' ');
@@ -1025,7 +1031,12 @@
 
 	seq_printf(m, "%i %i %u:%u ", mnt->mnt_id, mnt->mnt_parent->mnt_id,
 		   MAJOR(sb->s_dev), MINOR(sb->s_dev));
-	seq_dentry(m, mnt->mnt_root, " \t\n\\");
+	if (sb->s_op->show_path)
+		err = sb->s_op->show_path(m, mnt);
+	else
+		seq_dentry(m, mnt->mnt_root, " \t\n\\");
+	if (err)
+		goto out;
 	seq_putc(m, ' ');
 	seq_path_root(m, &mnt_path, &root, " \t\n\\");
 	if (root.mnt != p->root.mnt || root.dentry != p->root.dentry) {
@@ -1060,7 +1071,12 @@
 	seq_puts(m, " - ");
 	show_type(m, sb);
 	seq_putc(m, ' ');
-	mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
+	if (sb->s_op->show_devname)
+		err = sb->s_op->show_devname(m, mnt);
+	else
+		mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none");
+	if (err)
+		goto out;
 	seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw");
 	err = show_sb_opts(m, sb);
 	if (err)
@@ -1086,11 +1102,15 @@
 	int err = 0;
 
 	/* device */
-	if (mnt->mnt_devname) {
-		seq_puts(m, "device ");
-		mangle(m, mnt->mnt_devname);
-	} else
-		seq_puts(m, "no device");
+	if (mnt->mnt_sb->s_op->show_devname) {
+		err = mnt->mnt_sb->s_op->show_devname(m, mnt);
+	} else {
+		if (mnt->mnt_devname) {
+			seq_puts(m, "device ");
+			mangle(m, mnt->mnt_devname);
+		} else
+			seq_puts(m, "no device");
+	}
 
 	/* mount point */
 	seq_puts(m, " mounted on ");
@@ -1104,7 +1124,8 @@
 	/* optional statistics */
 	if (mnt->mnt_sb->s_op->show_stats) {
 		seq_putc(m, ' ');
-		err = mnt->mnt_sb->s_op->show_stats(m, mnt);
+		if (!err)
+			err = mnt->mnt_sb->s_op->show_stats(m, mnt);
 	}
 
 	seq_putc(m, '\n');