Commit 0acdb887 authored Sep 26, 2012 by Tao Ma Committed by Theodore Ts'o Sep 26, 2012

ext4: don't call update_backups() multiple times for the same bg



When performing an online resize, we add a bunch of groups at one time
in ext4_flex_group_add, so in most cases a lot of group descriptors
will be in the same group block. But in the end of this function,
update_backups will be called for every group descriptor and the same
block will be copied and journalled again and again.  It is really a
waste.

Fix things so we only update a particular bg descriptor block once and
skip subsequent updates of the same block.

Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

parent 7f1468d1

fs/ext4/resize.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -1460,6 +1460,7 @@ exit_journal:
		EXT4_DESC_PER_BLOCK(sb));
		int meta_bg = EXT4_HAS_INCOMPAT_FEATURE(sb,
		EXT4_FEATURE_INCOMPAT_META_BG);
		sector_t old_gdb = 0;

		update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
		sizeof(struct ext4_super_block), 0);
		@@ -1467,8 +1468,11 @@ exit_journal:
		struct buffer_head *gdb_bh;

		gdb_bh = sbi->s_group_desc[gdb_num];
		if (old_gdb == gdb_bh->b_blocknr)
		continue;
		update_backups(sb, gdb_bh->b_blocknr, gdb_bh->b_data,
		gdb_bh->b_size, meta_bg);
		old_gdb = gdb_bh->b_blocknr;
		}
		}
		exit:

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