[RFC PATCH 5/6] nfs/localio: refactor iocb initialization

[Mike Snitzer <snitzer@xxxxxxxxxx>]

From: Mike Snitzer <snitzer@xxxxxxxxxxxxxxx>

No functional change, but slighty cleaner.

Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxxxxxxx>
---
 fs/nfs/localio.c | 60 ++++++++++++++++++++++--------------------------
 1 file changed, 28 insertions(+), 32 deletions(-)

diff --git a/fs/nfs/localio.c b/fs/nfs/localio.c
index e551690e3f6b..d577fb27fd2f 100644
--- a/fs/nfs/localio.c
+++ b/fs/nfs/localio.c
@@ -287,23 +287,6 @@ nfs_local_open_fh(struct nfs_client *clp, const struct cred *cred,
 }
 EXPORT_SYMBOL_GPL(nfs_local_open_fh);
 
-static struct bio_vec *
-nfs_bvec_alloc_and_import_pagevec(struct page **pagevec,
-		unsigned int npages, gfp_t flags)
-{
-	struct bio_vec *bvec, *p;
-
-	bvec = kmalloc_array(npages, sizeof(*bvec), flags);
-	if (bvec != NULL) {
-		for (p = bvec; npages > 0; p++, pagevec++, npages--) {
-			p->bv_page = *pagevec;
-			p->bv_len = PAGE_SIZE;
-			p->bv_offset = 0;
-		}
-	}
-	return bvec;
-}
-
 static void
 nfs_local_iocb_free(struct nfs_local_kiocb *iocb)
 {
@@ -320,8 +303,9 @@ nfs_local_iocb_alloc(struct nfs_pgio_header *hdr,
 	iocb = kmalloc(sizeof(*iocb), flags);
 	if (iocb == NULL)
 		return NULL;
-	iocb->bvec = nfs_bvec_alloc_and_import_pagevec(hdr->page_array.pagevec,
-			hdr->page_array.npages, flags);
+	// FIXME: would do well to allocate memory based on NUMA node.
+	iocb->bvec = kmalloc_array(hdr->page_array.npages,
+				   sizeof(struct bio_vec), flags);
 	if (iocb->bvec == NULL) {
 		kfree(iocb);
 		return NULL;
@@ -344,7 +328,10 @@ static void
 nfs_local_iter_init(struct iov_iter *i, struct nfs_local_kiocb *iocb, int dir)
 {
 	struct nfs_pgio_header *hdr = iocb->hdr;
+	struct page **pagevec = hdr->page_array.pagevec;
 	u32 nf_dio_mem_align, nf_dio_offset_align;
+	unsigned long v, total;
+	size_t len;
 
 	if (iocb->kiocb.ki_flags & IOCB_DIRECT) {
 		nf_dio_mem_align = iocb->nf_dio_mem_align;
@@ -354,18 +341,29 @@ nfs_local_iter_init(struct iov_iter *i, struct nfs_local_kiocb *iocb, int dir)
 			nf_dio_offset_align = iocb->nf_dio_offset_align;
 	}
 
-	iov_iter_bvec(i, dir, iocb->bvec, hdr->page_array.npages,
+	v = 0;
+	total = hdr->args.count + hdr->args.pgbase;
+	while (total) {
+		len = min_t(size_t, total, PAGE_SIZE);
+		bvec_set_page(&iocb->bvec[v], *(pagevec++),
+			      len, 0);
+		total -= len;
+		++v;
+	}
+	WARN_ON_ONCE(v != hdr->page_array.npages);
+
+	iov_iter_bvec(i, dir, iocb->bvec, v,
 		      hdr->args.count + hdr->args.pgbase);
 	if (hdr->args.pgbase != 0)
 		iov_iter_advance(i, hdr->args.pgbase);
+
 	/* Verify the IO is DIO-aligned as needed */
 	if (iocb->kiocb.ki_flags & IOCB_DIRECT &&
 	    !iov_iter_is_aligned(i, nf_dio_mem_align - 1,
 				 nf_dio_offset_align - 1)) {
 		/* Fallback to buffered IO */
 		iocb->kiocb.ki_flags &= ~IOCB_DIRECT;
-		iocb->kiocb.ki_complete = NULL;
-		iocb->aio_complete_work = NULL;
+		iocb->kiocb.ki_filp->f_flags &= ~O_DIRECT;
 	}
 }
 
@@ -472,6 +470,10 @@ static void nfs_local_call_read(struct work_struct *work)
 	save_cred = override_creds(filp->f_cred);
 
 	nfs_local_iter_init(&iter, iocb, READ);
+	if (iocb->kiocb.ki_flags & IOCB_DIRECT) {
+		iocb->kiocb.ki_complete = nfs_local_read_aio_complete;
+		iocb->aio_complete_work = nfs_local_read_aio_complete_work;
+	}
 
 	status = filp->f_op->read_iter(&iocb->kiocb, &iter);
 	if (status != -EIOCBQUEUED) {
@@ -508,11 +510,6 @@ nfs_do_local_read(struct nfs_pgio_header *hdr,
 	nfs_local_pgio_init(hdr, call_ops);
 	hdr->res.eof = false;
 
-	if (iocb->kiocb.ki_flags & IOCB_DIRECT) {
-		iocb->kiocb.ki_complete = nfs_local_read_aio_complete;
-		iocb->aio_complete_work = nfs_local_read_aio_complete_work;
-	}
-
 	INIT_WORK(&iocb->work, nfs_local_call_read);
 	queue_work(nfslocaliod_workqueue, &iocb->work);
 
@@ -669,6 +666,10 @@ static void nfs_local_call_write(struct work_struct *work)
 	save_cred = override_creds(filp->f_cred);
 
 	nfs_local_iter_init(&iter, iocb, WRITE);
+	if (iocb->kiocb.ki_flags & IOCB_DIRECT) {
+		iocb->kiocb.ki_complete = nfs_local_write_aio_complete;
+		iocb->aio_complete_work = nfs_local_write_aio_complete_work;
+	}
 
 	file_start_write(filp);
 	status = filp->f_op->write_iter(&iocb->kiocb, &iter);
@@ -721,11 +722,6 @@ nfs_do_local_write(struct nfs_pgio_header *hdr,
 
 	nfs_set_local_verifier(hdr->inode, hdr->res.verf, hdr->args.stable);
 
-	if (iocb->kiocb.ki_flags & IOCB_DIRECT) {
-		iocb->kiocb.ki_complete = nfs_local_write_aio_complete;
-		iocb->aio_complete_work = nfs_local_write_aio_complete_work;
-	}
-
 	INIT_WORK(&iocb->work, nfs_local_call_write);
 	queue_work(nfslocaliod_workqueue, &iocb->work);
 
-- 
2.44.0