pstore: Create a convenient mount point for pstore

Using /dev/pstore as a mount point for the pstore filesystem is slightly
awkward.  We don't normally mount filesystems in /dev/ and the /dev/pstore
file isn't created automatically by anything.  While this method will
still work, we can create a persistent mount point in sysfs.  This will
put pstore on par with things like cgroups and efivarfs.

Signed-off-by: Josh Boyer <jwboyer@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>

2 files changed, 22 insertions, 6 deletions

diff --git a/Documentation/ABI/testing/pstore b/Documentation/ABI/testing/pstore
index ff1df4e3b059..5fca9f5e10a3 100644
--- a/Documentation/ABI/testing/pstore
+++ b/Documentation/ABI/testing/pstore
@@ -1,4 +1,4 @@
-Where:          /dev/pstore/...
+Where:          /sys/fs/pstore/... (or /dev/pstore/...)
 Date:           March 2011
 Kernel Version: 2.6.39
 Contact:        tony.luck@intel.com
@@ -11,9 +11,9 @@ Description:	Generic interface to platform dependent persistent storage.
                 of the console log is captured, but other interesting
                 data can also be saved.
 
-                # mount -t pstore -o kmsg_bytes=8000 - /dev/pstore
+                # mount -t pstore -o kmsg_bytes=8000 - /sys/fs/pstore
 
-                $ ls -l /dev/pstore
+                $ ls -l /sys/fs/pstore/
                 total 0
                 -r--r--r-- 1 root root 7896 Nov 30 15:38 dmesg-erst-1
 
@@ -27,9 +27,9 @@ Description:	Generic interface to platform dependent persistent storage.
                 the file will signal to the underlying persistent storage
                 device that it can reclaim the space for later re-use.
 
-                $ rm /dev/pstore/dmesg-erst-1
+                $ rm /sys/fs/pstore/dmesg-erst-1
 
-                The expectation is that all files in /dev/pstore
+                The expectation is that all files in /sys/fs/pstore/
                 will be saved elsewhere and erased from persistent store
                 soon after boot to free up space ready for the next
                 catastrophe.
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 67de74ca85f4..e4bcb2cf055a 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -418,9 +418,25 @@ static struct file_system_type pstore_fs_type = {
         .kill_sb        = pstore_kill_sb,
 };
 
+static struct kobject *pstore_kobj;
+
 static int __init init_pstore_fs(void)
 {
-        return register_filesystem(&pstore_fs_type);
+        int err = 0;
+
+        /* Create a convenient mount point for people to access pstore */
+        pstore_kobj = kobject_create_and_add("pstore", fs_kobj);
+        if (!pstore_kobj) {
+                err = -ENOMEM;
+                goto out;
+        }
+
+        err = register_filesystem(&pstore_fs_type);
+        if (err < 0)
+                kobject_put(pstore_kobj);
+
+out:
+        return err;
 }
 module_init(init_pstore_fs)