From 7277232374680595cdbc774fd246b206f56db015 Mon Sep 17 00:00:00 2001 From: Peter Osterlund Date: Tue, 14 Feb 2006 13:52:56 -0800 Subject: [PATCH] [PATCH] pktcdvd: Reduce stack usage Reduce stack usage in the pkt_start_write() function. Even though it's not currently a real problem, the pages and offsets arrays can be eliminated, which saves approximately 1000 bytes of stack space. Signed-off-by: Peter Osterlund Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/block/pktcdvd.c | 43 ++++++++++++++++------------------------- 1 file changed, 17 insertions(+), 26 deletions(-) diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c index 89d8fe014ef..93e44d0292a 100644 --- a/drivers/block/pktcdvd.c +++ b/drivers/block/pktcdvd.c @@ -645,7 +645,7 @@ static void pkt_copy_bio_data(struct bio *src_bio, int seg, int offs, struct pag * b) The data can be used as cache to avoid read requests if we receive a * new write request for the same zone. */ -static void pkt_make_local_copy(struct packet_data *pkt, struct page **pages, int *offsets) +static void pkt_make_local_copy(struct packet_data *pkt, struct bio_vec *bvec) { int f, p, offs; @@ -653,15 +653,15 @@ static void pkt_make_local_copy(struct packet_data *pkt, struct page **pages, in p = 0; offs = 0; for (f = 0; f < pkt->frames; f++) { - if (pages[f] != pkt->pages[p]) { - void *vfrom = kmap_atomic(pages[f], KM_USER0) + offsets[f]; + if (bvec[f].bv_page != pkt->pages[p]) { + void *vfrom = kmap_atomic(bvec[f].bv_page, KM_USER0) + bvec[f].bv_offset; void *vto = page_address(pkt->pages[p]) + offs; memcpy(vto, vfrom, CD_FRAMESIZE); kunmap_atomic(vfrom, KM_USER0); - pages[f] = pkt->pages[p]; - offsets[f] = offs; + bvec[f].bv_page = pkt->pages[p]; + bvec[f].bv_offset = offs; } else { - BUG_ON(offsets[f] != offs); + BUG_ON(bvec[f].bv_offset != offs); } offs += CD_FRAMESIZE; if (offs >= PAGE_SIZE) { @@ -991,18 +991,17 @@ try_next_bio: static void pkt_start_write(struct pktcdvd_device *pd, struct packet_data *pkt) { struct bio *bio; - struct page *pages[PACKET_MAX_SIZE]; - int offsets[PACKET_MAX_SIZE]; int f; int frames_write; + struct bio_vec *bvec = pkt->w_bio->bi_io_vec; for (f = 0; f < pkt->frames; f++) { - pages[f] = pkt->pages[(f * CD_FRAMESIZE) / PAGE_SIZE]; - offsets[f] = (f * CD_FRAMESIZE) % PAGE_SIZE; + bvec[f].bv_page = pkt->pages[(f * CD_FRAMESIZE) / PAGE_SIZE]; + bvec[f].bv_offset = (f * CD_FRAMESIZE) % PAGE_SIZE; } /* - * Fill-in pages[] and offsets[] with data from orig_bios. + * Fill-in bvec with data from orig_bios. */ frames_write = 0; spin_lock(&pkt->lock); @@ -1024,11 +1023,11 @@ static void pkt_start_write(struct pktcdvd_device *pd, struct packet_data *pkt) } if (src_bvl->bv_len - src_offs >= CD_FRAMESIZE) { - pages[f] = src_bvl->bv_page; - offsets[f] = src_bvl->bv_offset + src_offs; + bvec[f].bv_page = src_bvl->bv_page; + bvec[f].bv_offset = src_bvl->bv_offset + src_offs; } else { pkt_copy_bio_data(bio, segment, src_offs, - pages[f], offsets[f]); + bvec[f].bv_page, bvec[f].bv_offset); } src_offs += CD_FRAMESIZE; frames_write++; @@ -1042,7 +1041,7 @@ static void pkt_start_write(struct pktcdvd_device *pd, struct packet_data *pkt) BUG_ON(frames_write != pkt->write_size); if (test_bit(PACKET_MERGE_SEGS, &pd->flags) || (pkt->write_size < pkt->frames)) { - pkt_make_local_copy(pkt, pages, offsets); + pkt_make_local_copy(pkt, bvec); pkt->cache_valid = 1; } else { pkt->cache_valid = 0; @@ -1055,17 +1054,9 @@ static void pkt_start_write(struct pktcdvd_device *pd, struct packet_data *pkt) pkt->w_bio->bi_bdev = pd->bdev; pkt->w_bio->bi_end_io = pkt_end_io_packet_write; pkt->w_bio->bi_private = pkt; - for (f = 0; f < pkt->frames; f++) { - if ((f + 1 < pkt->frames) && (pages[f + 1] == pages[f]) && - (offsets[f + 1] = offsets[f] + CD_FRAMESIZE)) { - if (!bio_add_page(pkt->w_bio, pages[f], CD_FRAMESIZE * 2, offsets[f])) - BUG(); - f++; - } else { - if (!bio_add_page(pkt->w_bio, pages[f], CD_FRAMESIZE, offsets[f])) - BUG(); - } - } + for (f = 0; f < pkt->frames; f++) + if (!bio_add_page(pkt->w_bio, bvec[f].bv_page, CD_FRAMESIZE, bvec[f].bv_offset)) + BUG(); VPRINTK("pktcdvd: vcnt=%d\n", pkt->w_bio->bi_vcnt); atomic_set(&pkt->io_wait, 1); -- 2.20.1