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

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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>
This commit is contained in:
Tao Ma 2012-09-26 00:08:57 -04:00 committed by Theodore Ts'o
parent 7f1468d1d5
commit 0acdb8876f
1 changed files with 4 additions and 0 deletions
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4
fs/ext4/resize.c
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@ -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: