ext4: avoid duplicate writes of the backup bg descriptor blocks
authorYongqiang Yang <xiaoqiangnk@gmail.com>
Wed, 5 Sep 2012 05:27:50 +0000 (01:27 -0400)
committerTheodore Ts'o <tytso@mit.edu>
Wed, 5 Sep 2012 05:27:50 +0000 (01:27 -0400)
The resize code was needlessly writing the backup block group
descriptor blocks multiple times (once per block group) during an
online resize.

Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org
fs/ext4/resize.c

index a0ee26c23dd83375ac74928df688da6903e57c47..365d800ff8c1aaab9929cfdaa56c72401885d4dc 100644 (file)
@@ -1358,13 +1358,15 @@ exit_journal:
                err = err2;
 
        if (!err) {
-               int i;
+               int gdb_num = group / EXT4_DESC_PER_BLOCK(sb);
+               int gdb_num_end = ((group + flex_gd->count - 1) /
+                                  EXT4_DESC_PER_BLOCK(sb));
+
                update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
                               sizeof(struct ext4_super_block));
-               for (i = 0; i < flex_gd->count; i++, group++) {
+               for (; gdb_num <= gdb_num_end; gdb_num++) {
                        struct buffer_head *gdb_bh;
-                       int gdb_num;
-                       gdb_num = group / EXT4_BLOCKS_PER_GROUP(sb);
+
                        gdb_bh = sbi->s_group_desc[gdb_num];
                        update_backups(sb, gdb_bh->b_blocknr, gdb_bh->b_data,
                                       gdb_bh->b_size);