From: Zhi Yong Wu <wu...@linux.vnet.ibm.com>

  Introduce one new mount option '-o hottrack',
and add its parsing support.
  Its usage looks like:
   mount -o hottrack
   mount -o nouser,hottrack
   mount -o nouser,hottrack,loop
   mount -o hottrack,nouser

Signed-off-by: Zhi Yong Wu <wu...@linux.vnet.ibm.com>
---
 fs/hot_tracking.c            |   34 ++++++++++++++++++++++++++++++++++
 fs/hot_tracking.h            |    1 +
 fs/super.c                   |    5 +++++
 include/linux/hot_tracking.h |    7 +++++++
 4 files changed, 47 insertions(+), 0 deletions(-)

diff --git a/fs/hot_tracking.c b/fs/hot_tracking.c
index 52ed926..f97e8a6 100644
--- a/fs/hot_tracking.c
+++ b/fs/hot_tracking.c
@@ -465,6 +465,40 @@ void hot_rb_update_freqs(struct inode *inode, u64 start,
 }
 
 /*
+ * Regular mount options parser for -hottrack option.
+ * return false if no -hottrack is specified;
+ * otherwise return true. And the -hottrack will be
+ * removed from options.
+ */
+bool hot_track_parse_options(char *options)
+{
+       long len;
+       char *p;
+       static char opts_hot[] = "hottrack";
+
+       if (!options)
+               return false;
+
+       p = strstr(options, opts_hot);
+       if (!p)
+               return false;
+
+       while (p) {
+               len = options + strlen(options) - (p + strlen(opts_hot));
+               if (len == 0) {
+                       options[0] = '\0';
+                       break;
+               }
+
+               memmove(p, p + strlen(opts_hot) + 1, len);
+               p = strstr(options, opts_hot);
+       }
+
+       printk(KERN_INFO "vfs: turning on hot data tracking\n");
+       return true;
+}
+
+/*
  * Initialize kmem cache for hot_inode_item
  * and hot_range_item
  */
diff --git a/fs/hot_tracking.h b/fs/hot_tracking.h
index 2ba29e4..6bd09eb 100644
--- a/fs/hot_tracking.h
+++ b/fs/hot_tracking.h
@@ -37,6 +37,7 @@ void hot_rb_free_hot_inode_item(struct hot_inode_item *he);
 void hot_rb_update_freqs(struct inode *inode, u64 start, u64 len,
                        int rw);
 
+bool hot_track_parse_options(char *options);
 void __init hot_track_cache_init(void);
 
 #endif /* __HOT_TRACKING__ */
diff --git a/fs/super.c b/fs/super.c
index 0902cfa..7eb3b0c 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -34,6 +34,7 @@
 #include <linux/cleancache.h>
 #include <linux/fsnotify.h>
 #include <linux/lockdep.h>
+#include "hot_tracking.h"
 #include "internal.h"
 
 
@@ -1125,6 +1126,7 @@ mount_fs(struct file_system_type *type, int flags, const 
char *name, void *data)
        struct dentry *root;
        struct super_block *sb;
        char *secdata = NULL;
+       bool hottrack = false;
        int error = -ENOMEM;
 
        if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) {
@@ -1137,6 +1139,9 @@ mount_fs(struct file_system_type *type, int flags, const 
char *name, void *data)
                        goto out_free_secdata;
        }
 
+       if (data && hot_track_parse_options(data))
+               hottrack = true;
+
        root = type->mount(type, flags, name, data);
        if (IS_ERR(root)) {
                error = PTR_ERR(root);
diff --git a/include/linux/hot_tracking.h b/include/linux/hot_tracking.h
index a566f91..bb2a41c 100644
--- a/include/linux/hot_tracking.h
+++ b/include/linux/hot_tracking.h
@@ -20,6 +20,11 @@
 #include <linux/rbtree.h>
 #include <linux/kref.h>
 
+/*
+ * Flags for hot data tracking mount options.
+ */
+#define HOT_MOUNT_HOT_TRACK            (1 << 0)
+
 /* A tree that sits on the hot_info */
 struct hot_inode_tree {
        struct rb_root map;
@@ -89,6 +94,8 @@ struct hot_range_item {
 };
 
 struct hot_info {
+       unsigned long mount_opt;
+
        /* red-black tree that keeps track of fs-wide hot data */
        struct hot_inode_tree hot_inode_tree;
 };
-- 
1.7.6.5

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