Btrfs: Add mount option to enforce a max extent size

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 45 insertions, 1 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 2116728d1f98..b7323914bf5a 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -34,6 +34,7 @@
 #include <linux/statfs.h>
 #include <linux/compat.h>
 #include <linux/parser.h>
+#include <linux/ctype.h>
 #include "ctree.h"
 #include "disk-io.h"
 #include "transaction.h"
@@ -61,16 +62,42 @@ static void btrfs_put_super (struct super_block * sb)
 }
 
 enum {
-        Opt_subvol, Opt_nodatasum, Opt_nodatacow, Opt_err,
+        Opt_subvol, Opt_nodatasum, Opt_nodatacow, Opt_max_extent, Opt_err,
 };
 
 static match_table_t tokens = {
         {Opt_subvol, "subvol=%s"},
         {Opt_nodatasum, "nodatasum"},
         {Opt_nodatacow, "nodatacow"},
+        {Opt_max_extent, "max_extent=%s"},
         {Opt_err, NULL}
 };
 
+static unsigned long parse_size(char *str)
+{
+        unsigned long res;
+        int mult = 1;
+        char *end;
+        char last;
+
+        res = simple_strtoul(str, &end, 10);
+
+        last = end[0];
+        if (isalpha(last)) {
+                last = tolower(last);
+                switch (last) {
+                case 'g':
+                        mult *= 1024;
+                case 'm':
+                        mult *= 1024;
+                case 'k':
+                        mult *= 1024;
+                }
+                res = res * mult;
+        }
+        return res;
+}
+
 static int parse_options (char * options,
                           struct btrfs_root *root,
                           char **subvol_name)
@@ -118,6 +145,21 @@ static int parse_options (char * options,
                                 btrfs_set_opt(info->mount_opt, NODATASUM);
                         }
                         break;
+                case Opt_max_extent:
+                        if (info) {
+                                char *num = match_strdup(&args[0]);
+                                if (num) {
+                                        info->max_extent = parse_size(num);
+                                        kfree(num);
+
+                                        info->max_extent = max_t(u64,
+                                                         info->max_extent,
+                                                         root->sectorsize);
+                                        printk("btrfs: max_extent at %Lu\n",
+                                               info->max_extent);
+                                }
+                        }
+                        break;
                 default:
                         break;
                 }
@@ -329,6 +371,8 @@ static int btrfs_get_sb(struct file_system_type *fs_type,
         ret = btrfs_get_sb_bdev(fs_type, flags, dev_name, data,
                         btrfs_fill_super, mnt,
                         subvol_name ? subvol_name : "default");
+        if (subvol_name)
+                kfree(subvol_name);
         return ret;
 }