block: Kill bio_segments()/bi_vcnt usage
authorKent Overstreet <kmo@daterainc.com>
Tue, 24 Sep 2013 23:26:05 +0000 (16:26 -0700)
committerKent Overstreet <kmo@daterainc.com>
Sun, 24 Nov 2013 06:33:51 +0000 (22:33 -0800)
When we start sharing biovecs, keeping bi_vcnt accurate for splits is
going to be error prone - and unnecessary, if we refactor some code.

So bio_segments() has to go - but most of the existing users just needed
to know if the bio had multiple segments, which is easier - add a
bio_multiple_segments() for them.

(Two of the current uses of bio_segments() are going to go away in a
couple patches, but the current implementation of bio_segments() is
unsafe as soon as we start doing driver conversions for immutable
biovecs - so implement a dumb version for bisectability, it'll go away
in a couple patches)

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Neil Brown <neilb@suse.de>
Cc: Nagalakshmi Nandigama <Nagalakshmi.Nandigama@lsi.com>
Cc: Sreekanth Reddy <Sreekanth.Reddy@lsi.com>
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
drivers/block/ps3disk.c
drivers/md/bcache/io.c
drivers/md/raid0.c
drivers/md/raid10.c
drivers/message/fusion/mptsas.c
drivers/scsi/libsas/sas_expander.c
drivers/scsi/mpt2sas/mpt2sas_transport.c
drivers/scsi/mpt3sas/mpt3sas_transport.c
fs/bio.c
include/linux/bio.h

index 1c6edb9a99600eabd63d55bb07fefe59b5af48c0..c120d70d3fb3b31fdfb584859a8cdd5bf0849dab 100644 (file)
@@ -101,10 +101,9 @@ static void ps3disk_scatter_gather(struct ps3_storage_device *dev,
 
        rq_for_each_segment(bvec, req, iter) {
                unsigned long flags;
-               dev_dbg(&dev->sbd.core,
-                       "%s:%u: bio %u: %u segs %u sectors from %lu\n",
-                       __func__, __LINE__, i, bio_segments(iter.bio),
-                       bio_sectors(iter.bio), iter.bio->bi_iter.bi_sector);
+               dev_dbg(&dev->sbd.core, "%s:%u: bio %u: %u sectors from %lu\n",
+                       __func__, __LINE__, i, bio_sectors(iter.bio),
+                       iter.bio->bi_iter.bi_sector);
 
                size = bvec.bv_len;
                buf = bvec_kmap_irq(&bvec, &flags);
index 9b5b6a41a9b66f0f8ff25f68c4b42b09089ca2a4..6e04f3bb02864eb7c2cf71a094af98903b5c4c1c 100644 (file)
@@ -24,7 +24,8 @@ static void bch_generic_make_request_hack(struct bio *bio)
        if (bio->bi_iter.bi_idx) {
                struct bio_vec bv;
                struct bvec_iter iter;
-               struct bio *clone = bio_alloc(GFP_NOIO, bio_segments(bio));
+               unsigned segs = bio_segments(bio);
+               struct bio *clone = bio_alloc(GFP_NOIO, segs);
 
                bio_for_each_segment(bv, bio, iter)
                        clone->bi_io_vec[clone->bi_vcnt++] = bv;
@@ -32,7 +33,7 @@ static void bch_generic_make_request_hack(struct bio *bio)
                clone->bi_iter.bi_sector = bio->bi_iter.bi_sector;
                clone->bi_bdev          = bio->bi_bdev;
                clone->bi_rw            = bio->bi_rw;
-               clone->bi_vcnt          = bio_segments(bio);
+               clone->bi_vcnt          = segs;
                clone->bi_iter.bi_size  = bio->bi_iter.bi_size;
 
                clone->bi_private       = bio;
@@ -133,40 +134,32 @@ out:
 
 static unsigned bch_bio_max_sectors(struct bio *bio)
 {
-       unsigned ret = bio_sectors(bio);
        struct request_queue *q = bdev_get_queue(bio->bi_bdev);
-       unsigned max_segments = min_t(unsigned, BIO_MAX_PAGES,
-                                     queue_max_segments(q));
+       struct bio_vec bv;
+       struct bvec_iter iter;
+       unsigned ret = 0, seg = 0;
 
        if (bio->bi_rw & REQ_DISCARD)
-               return min(ret, q->limits.max_discard_sectors);
-
-       if (bio_segments(bio) > max_segments ||
-           q->merge_bvec_fn) {
-               struct bio_vec bv;
-               struct bvec_iter iter;
-               unsigned seg = 0;
-
-               ret = 0;
+               return min(bio_sectors(bio), q->limits.max_discard_sectors);
 
-               bio_for_each_segment(bv, bio, iter) {
-                       struct bvec_merge_data bvm = {
-                               .bi_bdev        = bio->bi_bdev,
-                               .bi_sector      = bio->bi_iter.bi_sector,
-                               .bi_size        = ret << 9,
-                               .bi_rw          = bio->bi_rw,
-                       };
-
-                       if (seg == max_segments)
-                               break;
+       bio_for_each_segment(bv, bio, iter) {
+               struct bvec_merge_data bvm = {
+                       .bi_bdev        = bio->bi_bdev,
+                       .bi_sector      = bio->bi_iter.bi_sector,
+                       .bi_size        = ret << 9,
+                       .bi_rw          = bio->bi_rw,
+               };
+
+               if (seg == min_t(unsigned, BIO_MAX_PAGES,
+                                queue_max_segments(q)))
+                       break;
 
-                       if (q->merge_bvec_fn &&
-                           q->merge_bvec_fn(q, &bvm, &bv) < (int) bv.bv_len)
-                               break;
+               if (q->merge_bvec_fn &&
+                   q->merge_bvec_fn(q, &bvm, &bv) < (int) bv.bv_len)
+                       break;
 
-                       seg++;
-                       ret += bv.bv_len >> 9;
-               }
+               seg++;
+               ret += bv.bv_len >> 9;
        }
 
        ret = min(ret, queue_max_sectors(q));
index e38d1d3226f3a60b5031cad427cf81c32d244a15..8ee1a6c658b445c0ad858f7703dc1a68f4bf82c5 100644 (file)
@@ -528,7 +528,7 @@ static void raid0_make_request(struct mddev *mddev, struct bio *bio)
                sector_t sector = bio->bi_iter.bi_sector;
                struct bio_pair *bp;
                /* Sanity check -- queue functions should prevent this happening */
-               if (bio_segments(bio) > 1)
+               if (bio_multiple_segments(bio))
                        goto bad_map;
                /* This is a one page bio that upper layers
                 * refuse to split for us, so we need to split it.
index dbf3b63c2754fe3ad0036d78b1564ff4c71fdf05..ac4bfa438c5790acc95820b13b1f049b5327051c 100644 (file)
@@ -1188,7 +1188,7 @@ static void make_request(struct mddev *mddev, struct bio * bio)
                         || conf->prev.near_copies < conf->prev.raid_disks))) {
                struct bio_pair *bp;
                /* Sanity check -- queue functions should prevent this happening */
-               if (bio_segments(bio) > 1)
+               if (bio_multiple_segments(bio))
                        goto bad_map;
                /* This is a one page bio that upper layers
                 * refuse to split for us, so we need to split it.
index dd239bdbfcb4a0877db2ab49aa3c27a81eec7dd1..00d339c361fc0ecbd0b9b086e8c5756d28983d77 100644 (file)
@@ -2235,10 +2235,10 @@ static int mptsas_smp_handler(struct Scsi_Host *shost, struct sas_rphy *rphy,
        }
 
        /* do we need to support multiple segments? */
-       if (bio_segments(req->bio) > 1 || bio_segments(rsp->bio) > 1) {
-               printk(MYIOC_s_ERR_FMT "%s: multiple segments req %u %u, rsp %u %u\n",
-                   ioc->name, __func__, bio_segments(req->bio), blk_rq_bytes(req),
-                   bio_segments(rsp->bio), blk_rq_bytes(rsp));
+       if (bio_multiple_segments(req->bio) ||
+           bio_multiple_segments(rsp->bio)) {
+               printk(MYIOC_s_ERR_FMT "%s: multiple segments req %u, rsp %u\n",
+                   ioc->name, __func__, blk_rq_bytes(req), blk_rq_bytes(rsp));
                return -EINVAL;
        }
 
index 446b85110a1fc0a69b07e42bb3ecc7144d76d1ce..0cac7d8fd0f7cac75b0ecc2d63662d18eeda4a56 100644 (file)
@@ -2163,10 +2163,10 @@ int sas_smp_handler(struct Scsi_Host *shost, struct sas_rphy *rphy,
        }
 
        /* do we need to support multiple segments? */
-       if (bio_segments(req->bio) > 1 || bio_segments(rsp->bio) > 1) {
-               printk("%s: multiple segments req %u %u, rsp %u %u\n",
-                      __func__, bio_segments(req->bio), blk_rq_bytes(req),
-                      bio_segments(rsp->bio), blk_rq_bytes(rsp));
+       if (bio_multiple_segments(req->bio) ||
+           bio_multiple_segments(rsp->bio)) {
+               printk("%s: multiple segments req %u, rsp %u\n",
+                      __func__, blk_rq_bytes(req), blk_rq_bytes(rsp));
                return -EINVAL;
        }
 
index 7143e86af326ec61c7a46d21cd9082a88848e9a5..410f4a3e88887a6f0087c06f9da42f22b61f556d 100644 (file)
@@ -1943,7 +1943,7 @@ _transport_smp_handler(struct Scsi_Host *shost, struct sas_rphy *rphy,
        ioc->transport_cmds.status = MPT2_CMD_PENDING;
 
        /* Check if the request is split across multiple segments */
-       if (bio_segments(req->bio) > 1) {
+       if (bio_multiple_segments(req->bio)) {
                u32 offset = 0;
 
                /* Allocate memory and copy the request */
@@ -1975,7 +1975,7 @@ _transport_smp_handler(struct Scsi_Host *shost, struct sas_rphy *rphy,
 
        /* Check if the response needs to be populated across
         * multiple segments */
-       if (bio_segments(rsp->bio) > 1) {
+       if (bio_multiple_segments(rsp->bio)) {
                pci_addr_in = pci_alloc_consistent(ioc->pdev, blk_rq_bytes(rsp),
                    &pci_dma_in);
                if (!pci_addr_in) {
@@ -2042,7 +2042,7 @@ _transport_smp_handler(struct Scsi_Host *shost, struct sas_rphy *rphy,
        sgl_flags = (MPI2_SGE_FLAGS_SIMPLE_ELEMENT |
            MPI2_SGE_FLAGS_END_OF_BUFFER | MPI2_SGE_FLAGS_HOST_TO_IOC);
        sgl_flags = sgl_flags << MPI2_SGE_FLAGS_SHIFT;
-       if (bio_segments(req->bio) > 1) {
+       if (bio_multiple_segments(req->bio)) {
                ioc->base_add_sg_single(psge, sgl_flags |
                    (blk_rq_bytes(req) - 4), pci_dma_out);
        } else {
@@ -2058,7 +2058,7 @@ _transport_smp_handler(struct Scsi_Host *shost, struct sas_rphy *rphy,
            MPI2_SGE_FLAGS_LAST_ELEMENT | MPI2_SGE_FLAGS_END_OF_BUFFER |
            MPI2_SGE_FLAGS_END_OF_LIST);
        sgl_flags = sgl_flags << MPI2_SGE_FLAGS_SHIFT;
-       if (bio_segments(rsp->bio) > 1) {
+       if (bio_multiple_segments(rsp->bio)) {
                ioc->base_add_sg_single(psge, sgl_flags |
                    (blk_rq_bytes(rsp) + 4), pci_dma_in);
        } else {
@@ -2103,7 +2103,7 @@ _transport_smp_handler(struct Scsi_Host *shost, struct sas_rphy *rphy,
                    le16_to_cpu(mpi_reply->ResponseDataLength);
                /* check if the resp needs to be copied from the allocated
                 * pci mem */
-               if (bio_segments(rsp->bio) > 1) {
+               if (bio_multiple_segments(rsp->bio)) {
                        u32 offset = 0;
                        u32 bytes_to_copy =
                            le16_to_cpu(mpi_reply->ResponseDataLength);
index 196a67f2e95fc1f0a023e5c5fa2e3e15f5bc6da3..65170cb1a00fa5fa0ca3c95a94e3ed686edca9f7 100644 (file)
@@ -1926,7 +1926,7 @@ _transport_smp_handler(struct Scsi_Host *shost, struct sas_rphy *rphy,
        ioc->transport_cmds.status = MPT3_CMD_PENDING;
 
        /* Check if the request is split across multiple segments */
-       if (req->bio->bi_vcnt > 1) {
+       if (bio_multiple_segments(req->bio)) {
                u32 offset = 0;
 
                /* Allocate memory and copy the request */
@@ -1958,7 +1958,7 @@ _transport_smp_handler(struct Scsi_Host *shost, struct sas_rphy *rphy,
 
        /* Check if the response needs to be populated across
         * multiple segments */
-       if (rsp->bio->bi_vcnt > 1) {
+       if (bio_multiple_segments(rsp->bio)) {
                pci_addr_in = pci_alloc_consistent(ioc->pdev, blk_rq_bytes(rsp),
                    &pci_dma_in);
                if (!pci_addr_in) {
@@ -2019,7 +2019,7 @@ _transport_smp_handler(struct Scsi_Host *shost, struct sas_rphy *rphy,
        mpi_request->RequestDataLength = cpu_to_le16(blk_rq_bytes(req) - 4);
        psge = &mpi_request->SGL;
 
-       if (req->bio->bi_vcnt > 1)
+       if (bio_multiple_segments(req->bio))
                ioc->build_sg(ioc, psge, pci_dma_out, (blk_rq_bytes(req) - 4),
                    pci_dma_in, (blk_rq_bytes(rsp) + 4));
        else
@@ -2064,7 +2064,7 @@ _transport_smp_handler(struct Scsi_Host *shost, struct sas_rphy *rphy,
 
                /* check if the resp needs to be copied from the allocated
                 * pci mem */
-               if (rsp->bio->bi_vcnt > 1) {
+               if (bio_multiple_segments(rsp->bio)) {
                        u32 offset = 0;
                        u32 bytes_to_copy =
                            le16_to_cpu(mpi_reply->ResponseDataLength);
index f61e59b3881525bff5b5b36953481530e5511386..e32f2ffc3f33f063551bcc0e5f12fad6b712a079 100644 (file)
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -1733,7 +1733,7 @@ struct bio_pair *bio_split(struct bio *bi, int first_sectors)
        trace_block_split(bdev_get_queue(bi->bi_bdev), bi,
                                bi->bi_iter.bi_sector + first_sectors);
 
-       BUG_ON(bio_segments(bi) > 1);
+       BUG_ON(bio_multiple_segments(bi));
        atomic_set(&bp->cnt, 3);
        bp->error = 0;
        bp->bio1 = *bi;
index 930cb73c894b309aa3643df6a0242c1bbb39f2c9..aea9896a6289c74785a12e7971b6b8a42518efbc 100644 (file)
 #define bio_offset(bio)                bio_iter_offset((bio), (bio)->bi_iter)
 #define bio_iovec(bio)         bio_iter_iovec((bio), (bio)->bi_iter)
 
-#define bio_segments(bio)      ((bio)->bi_vcnt - (bio)->bi_iter.bi_idx)
+#define bio_multiple_segments(bio)                             \
+       ((bio)->bi_iter.bi_size != bio_iovec(bio).bv_len)
 #define bio_sectors(bio)       ((bio)->bi_iter.bi_size >> 9)
 #define bio_end_sector(bio)    ((bio)->bi_iter.bi_sector + bio_sectors((bio)))
 
+/*
+ * Check whether this bio carries any data or not. A NULL bio is allowed.
+ */
+static inline bool bio_has_data(struct bio *bio)
+{
+       if (bio &&
+           bio->bi_iter.bi_size &&
+           !(bio->bi_rw & REQ_DISCARD))
+               return true;
+
+       return false;
+}
+
+static inline bool bio_is_rw(struct bio *bio)
+{
+       if (!bio_has_data(bio))
+               return false;
+
+       if (bio->bi_rw & BIO_NO_ADVANCE_ITER_MASK)
+               return false;
+
+       return true;
+}
+
+static inline bool bio_mergeable(struct bio *bio)
+{
+       if (bio->bi_rw & REQ_NOMERGE_FLAGS)
+               return false;
+
+       return true;
+}
+
 static inline unsigned int bio_cur_bytes(struct bio *bio)
 {
-       if (bio->bi_vcnt)
+       if (bio_has_data(bio))
                return bio_iovec(bio).bv_len;
        else /* dataless requests such as discard */
                return bio->bi_iter.bi_size;
@@ -111,7 +144,7 @@ static inline unsigned int bio_cur_bytes(struct bio *bio)
 
 static inline void *bio_data(struct bio *bio)
 {
-       if (bio->bi_vcnt)
+       if (bio_has_data(bio))
                return page_address(bio_page(bio)) + bio_offset(bio);
 
        return NULL;
@@ -221,6 +254,18 @@ static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
 
 #define bio_iter_last(bvec, iter) ((iter).bi_size == (bvec).bv_len)
 
+static inline unsigned bio_segments(struct bio *bio)
+{
+       unsigned segs = 0;
+       struct bio_vec bv;
+       struct bvec_iter iter;
+
+       bio_for_each_segment(bv, bio, iter)
+               segs++;
+
+       return segs;
+}
+
 /*
  * get a reference to a bio, so it won't disappear. the intended use is
  * something like:
@@ -434,36 +479,6 @@ static inline char *__bio_kmap_irq(struct bio *bio, unsigned short idx,
        __bio_kmap_irq((bio), (bio)->bi_iter.bi_idx, (flags))
 #define bio_kunmap_irq(buf,flags)      __bio_kunmap_irq(buf, flags)
 
-/*
- * Check whether this bio carries any data or not. A NULL bio is allowed.
- */
-static inline bool bio_has_data(struct bio *bio)
-{
-       if (bio && bio->bi_vcnt)
-               return true;
-
-       return false;
-}
-
-static inline bool bio_is_rw(struct bio *bio)
-{
-       if (!bio_has_data(bio))
-               return false;
-
-       if (bio->bi_rw & REQ_WRITE_SAME)
-               return false;
-
-       return true;
-}
-
-static inline bool bio_mergeable(struct bio *bio)
-{
-       if (bio->bi_rw & REQ_NOMERGE_FLAGS)
-               return false;
-
-       return true;
-}
-
 /*
  * BIO list management for use by remapping drivers (e.g. DM or MD) and loop.
  *
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