linux-kernel - [PATCH RFC V2 10/17] fs/dax: Remove unused size parameter

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Date:   Fri, 17 Jul 2020 00:20:49 -0700
From:   ira.weiny@...el.com
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Ira Weiny <ira.weiny@...el.com>,
        Ben Widawsky <ben.widawsky@...el.com>,
        Dan Williams <dan.j.williams@...el.com>, x86@...nel.org,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Fenghua Yu <fenghua.yu@...el.com>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-nvdimm@...ts.01.org,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        linux-kselftest@...r.kernel.org
Subject: [PATCH RFC V2 10/17] fs/dax: Remove unused size parameter

From: Ira Weiny <ira.weiny@...el.com>

Passing size to copy_user_dax implies it can copy variable sizes of data
when in fact it calls copy_user_page() which is exactly a page.

We are safe because the only caller uses PAGE_SIZE anyway so just remove
the variable for clarity.

While we are at it change copy_user_dax() to copy_cow_page_dax() to make
it clear it is a singleton helper for this one case not implementing
what dax_iomap_actor() does.

Reviewed-by: Ben Widawsky <ben.widawsky@...el.com>
Reviewed-by: Dan Williams <dan.j.williams@...el.com>
Signed-off-by: Ira Weiny <ira.weiny@...el.com>
---
 fs/dax.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 11b16729b86f..3e0babeb0365 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -680,21 +680,20 @@ int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
 	return __dax_invalidate_entry(mapping, index, false);
 }
 
-static int copy_user_dax(struct block_device *bdev, struct dax_device *dax_dev,
-		sector_t sector, size_t size, struct page *to,
-		unsigned long vaddr)
+static int copy_cow_page_dax(struct block_device *bdev, struct dax_device *dax_dev,
+			     sector_t sector, struct page *to, unsigned long vaddr)
 {
 	void *vto, *kaddr;
 	pgoff_t pgoff;
 	long rc;
 	int id;
 
-	rc = bdev_dax_pgoff(bdev, sector, size, &pgoff);
+	rc = bdev_dax_pgoff(bdev, sector, PAGE_SIZE, &pgoff);
 	if (rc)
 		return rc;
 
 	id = dax_read_lock();
-	rc = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size), &kaddr, NULL);
+	rc = dax_direct_access(dax_dev, pgoff, PHYS_PFN(PAGE_SIZE), &kaddr, NULL);
 	if (rc < 0) {
 		dax_read_unlock(id);
 		return rc;
@@ -1305,8 +1304,8 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
 			clear_user_highpage(vmf->cow_page, vaddr);
 			break;
 		case IOMAP_MAPPED:
-			error = copy_user_dax(iomap.bdev, iomap.dax_dev,
-					sector, PAGE_SIZE, vmf->cow_page, vaddr);
+			error = copy_cow_page_dax(iomap.bdev, iomap.dax_dev,
+						  sector, vmf->cow_page, vaddr);
 			break;
 		default:
 			WARN_ON_ONCE(1);
-- 
2.28.0.rc0.12.gb6a658bd00c9