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simplify some logic in ext4_mb_normalize_request 

While reading through some of the mballoc code it seems that a couple
spots in the size normalization function could be streamlined.

The test for non-overlapping PAs can be or'd for the start & end
conditions, and the tests for adjacent PAs can be else-if'd - 
it's essentially independently testing:

	if (A + B <= C)
		...
	if (A > C)
		...

These cannot both be true so it seems like the else-if might
be slightly more efficient and/or informative.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Eric Sandeen 2009-08-17 23:55:24 -04:00 committed by Theodore Ts'o
parent 0373130d5b
commit 38877f4e8d
1 changed files with 4 additions and 9 deletions
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13
fs/ext4/mballoc.c
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@ -3184,23 +3184,18 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,
BUG_ON(!(ac->ac_o_ex.fe_logical >= pa_end ||
ac->ac_o_ex.fe_logical < pa->pa_lstart));
/* skip PA normalized request doesn't overlap with */
if (pa->pa_lstart >= end) {
spin_unlock(&pa->pa_lock);
continue;
}
if (pa_end <= start) {
/* skip PAs this normalized request doesn't overlap with */
if (pa->pa_lstart >= end || pa_end <= start) {
spin_unlock(&pa->pa_lock);
continue;
}
BUG_ON(pa->pa_lstart <= start && pa_end >= end);
/* adjust start or end to be adjacent to this pa */
if (pa_end <= ac->ac_o_ex.fe_logical) {
BUG_ON(pa_end < start);
start = pa_end;
}
if (pa->pa_lstart > ac->ac_o_ex.fe_logical) {
} else if (pa->pa_lstart > ac->ac_o_ex.fe_logical) {
BUG_ON(pa->pa_lstart > end);
end = pa->pa_lstart;
}