Commit a1329fe8 authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds

[PATCH] loop inefficiency fix

Patch from Hugh Dickins <hugh@veritas.com>

The loop driver's loop over elements of bi_io_vec is in lo_send and
lo_receive: iterating that same transfer bi_vcnt times at the level above is,
er, excessive.  (And no need to increment bi_idx here.)
parent 87afb5f6
......@@ -350,15 +350,10 @@ static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
int ret;
pos = ((loff_t) bio->bi_sector << 9) + lo->lo_offset;
do {
if (bio_rw(bio) == WRITE)
ret = lo_send(lo, bio, lo->lo_blocksize, pos);
else
ret = lo_receive(lo, bio, lo->lo_blocksize, pos);
} while (++bio->bi_idx < bio->bi_vcnt);
if (bio_rw(bio) == WRITE)
ret = lo_send(lo, bio, lo->lo_blocksize, pos);
else
ret = lo_receive(lo, bio, lo->lo_blocksize, pos);
return ret;
}
......
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