pstore: use mount option instead sysfs to tweak kmsg_bytes
Luck, Tony [Fri, 18 Mar 2011 22:33:43 +0000 (15:33 -0700)]
/sys/fs is a somewhat strange way to tweak what could more
obviously be tuned with a mount option.

Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/ABI/testing/pstore
Documentation/ABI/testing/sysfs-fs-pstore [deleted file]
fs/pstore/inode.c
fs/pstore/internal.h
fs/pstore/platform.c

index f1fb2a0..ddf451e 100644 (file)
@@ -1,6 +1,6 @@
 Where:         /dev/pstore/...
-Date:          January 2011
-Kernel Version: 2.6.38
+Date:          March 2011
+Kernel Version: 2.6.39
 Contact:       tony.luck@intel.com
 Description:   Generic interface to platform dependent persistent storage.
 
@@ -11,7 +11,7 @@ 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 - /dev/pstore
+               # mount -t pstore -o kmsg_bytes=8000 - /dev/pstore
 
                $ ls -l /dev/pstore
                total 0
@@ -33,3 +33,9 @@ Description:  Generic interface to platform dependent persistent storage.
                will be saved elsewhere and erased from persistent store
                soon after boot to free up space ready for the next
                catastrophe.
+
+               The 'kmsg_bytes' mount option changes the target amount of
+               data saved on each oops/panic. Pstore saves (possibly
+               multiple) files based on the record size of the underlying
+               persistent storage until at least this amount is reached.
+               Default is 10 Kbytes.
diff --git a/Documentation/ABI/testing/sysfs-fs-pstore b/Documentation/ABI/testing/sysfs-fs-pstore
deleted file mode 100644 (file)
index 8e659d8..0000000
+++ /dev/null
@@ -1,7 +0,0 @@
-What:          /sys/fs/pstore/kmsg_bytes
-Date:          January 2011
-Kernel Version: 2.6.38
-Contact:       "Tony Luck" <tony.luck@intel.com>
-Description:
-               Controls amount of console log that will be saved
-               to persistent store on oops/panic.
index f777f29..977ed27 100644 (file)
@@ -27,6 +27,7 @@
 #include <linux/string.h>
 #include <linux/mount.h>
 #include <linux/ramfs.h>
+#include <linux/parser.h>
 #include <linux/sched.h>
 #include <linux/magic.h>
 #include <linux/pstore.h>
@@ -112,10 +113,52 @@ static struct inode *pstore_get_inode(struct super_block *sb,
        return inode;
 }
 
+enum {
+       Opt_kmsg_bytes, Opt_err
+};
+
+static const match_table_t tokens = {
+       {Opt_kmsg_bytes, "kmsg_bytes=%u"},
+       {Opt_err, NULL}
+};
+
+static void parse_options(char *options)
+{
+       char            *p;
+       substring_t     args[MAX_OPT_ARGS];
+       int             option;
+
+       if (!options)
+               return;
+
+       while ((p = strsep(&options, ",")) != NULL) {
+               int token;
+
+               if (!*p)
+                       continue;
+
+               token = match_token(p, tokens, args);
+               switch (token) {
+               case Opt_kmsg_bytes:
+                       if (!match_int(&args[0], &option))
+                               pstore_set_kmsg_bytes(option);
+                       break;
+               }
+       }
+}
+
+static int pstore_remount(struct super_block *sb, int *flags, char *data)
+{
+       parse_options(data);
+
+       return 0;
+}
+
 static const struct super_operations pstore_ops = {
        .statfs         = simple_statfs,
        .drop_inode     = generic_delete_inode,
        .evict_inode    = pstore_evict_inode,
+       .remount_fs     = pstore_remount,
        .show_options   = generic_show_options,
 };
 
@@ -215,6 +258,8 @@ int pstore_fill_super(struct super_block *sb, void *data, int silent)
        sb->s_op                = &pstore_ops;
        sb->s_time_gran         = 1;
 
+       parse_options(data);
+
        inode = pstore_get_inode(sb, NULL, S_IFDIR | 0755, 0);
        if (!inode) {
                err = -ENOMEM;
@@ -258,28 +303,7 @@ static struct file_system_type pstore_fs_type = {
 
 static int __init init_pstore_fs(void)
 {
-       int rc = 0;
-       struct kobject *pstorefs_kobj;
-
-       pstorefs_kobj = kobject_create_and_add("pstore", fs_kobj);
-       if (!pstorefs_kobj) {
-               rc = -ENOMEM;
-               goto done;
-       }
-
-       rc = sysfs_create_file(pstorefs_kobj, &pstore_kmsg_bytes_attr.attr);
-       if (rc)
-               goto done1;
-
-       rc = register_filesystem(&pstore_fs_type);
-       if (rc == 0)
-               goto done;
-
-       sysfs_remove_file(pstorefs_kobj, &pstore_kmsg_bytes_attr.attr);
-done1:
-       kobject_put(pstorefs_kobj);
-done:
-       return rc;
+       return register_filesystem(&pstore_fs_type);
 }
 module_init(init_pstore_fs)
 
index 76c26d2..8c9f23e 100644 (file)
@@ -1,7 +1,6 @@
+extern void    pstore_set_kmsg_bytes(int);
 extern void    pstore_get_records(void);
 extern int     pstore_mkfile(enum pstore_type_id, char *psname, u64 id,
                              char *data, size_t size,
                              struct timespec time, int (*erase)(u64));
 extern int     pstore_is_mounted(void);
-
-extern struct kobj_attribute pstore_kmsg_bytes_attr;
index 705fdf8..ce9ad84 100644 (file)
 static DEFINE_SPINLOCK(pstore_lock);
 static struct pstore_info *psinfo;
 
-/* How much of the console log to snapshot. /sys/fs/pstore/kmsg_bytes */
+/* How much of the console log to snapshot */
 static unsigned long kmsg_bytes = 10240;
 
-static ssize_t b_show(struct kobject *kobj,
-                     struct kobj_attribute *attr, char *buf)
+void pstore_set_kmsg_bytes(int bytes)
 {
-       return snprintf(buf, PAGE_SIZE, "%lu\n", kmsg_bytes);
+       kmsg_bytes = bytes;
 }
 
-static ssize_t b_store(struct kobject *kobj, struct kobj_attribute *attr,
-                      const char *buf, size_t count)
-{
-       return (sscanf(buf, "%lu", &kmsg_bytes) > 0) ? count : 0;
-}
-
-struct kobj_attribute pstore_kmsg_bytes_attr =
-       __ATTR(kmsg_bytes, S_IRUGO | S_IWUSR, b_show, b_store);
-
 /* Tag each group of saved records with a sequence number */
 static int     oopscount;