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From:   Shiyang Ruan <ruansy.fnst@fujitsu.com>
To:     <djwong@kernel.org>, <hch@lst.de>, <linux-xfs@vger.kernel.org>
CC:     <ruansy.fnst@fujitsu.com>, <dan.j.williams@intel.com>,
        <david@fromorbit.com>, <linux-fsdevel@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <nvdimm@lists.linux.dev>,
        <rgoldwyn@suse.de>, <viro@zeniv.linux.org.uk>,
        <willy@infradead.org>, Ritesh Harjani <riteshh@linux.ibm.com>
Subject: [PATCH v7 1/8] fsdax: Output address in dax_iomap_pfn() and rename it
Date:   Mon, 16 Aug 2021 14:03:52 +0800
Message-ID: <20210816060359.1442450-2-ruansy.fnst@fujitsu.com>
In-Reply-To: <20210816060359.1442450-1-ruansy.fnst@fujitsu.com>
References: <20210816060359.1442450-1-ruansy.fnst@fujitsu.com>
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Precedence: bulk

Add address output in dax_iomap_pfn() in order to perform a memcpy() in
CoW case.  Since this function both output address and pfn, rename it to
dax_iomap_direct_access().

Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
---
 fs/dax.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 118c9e2923f5..9fb6218f42be 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1010,8 +1010,8 @@ static sector_t dax_iomap_sector(const struct iomap *iomap, loff_t pos)
 	return (iomap->addr + (pos & PAGE_MASK) - iomap->offset) >> 9;
 }
 
-static int dax_iomap_pfn(const struct iomap *iomap, loff_t pos, size_t size,
-			 pfn_t *pfnp)
+static int dax_iomap_direct_access(const struct iomap *iomap, loff_t pos,
+		size_t size, void **kaddr, pfn_t *pfnp)
 {
 	const sector_t sector = dax_iomap_sector(iomap, pos);
 	pgoff_t pgoff;
@@ -1023,11 +1023,13 @@ static int dax_iomap_pfn(const struct iomap *iomap, loff_t pos, size_t size,
 		return rc;
 	id = dax_read_lock();
 	length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size),
-				   NULL, pfnp);
+				   kaddr, pfnp);
 	if (length < 0) {
 		rc = length;
 		goto out;
 	}
+	if (!pfnp)
+		goto out_check_addr;
 	rc = -EINVAL;
 	if (PFN_PHYS(length) < size)
 		goto out;
@@ -1037,6 +1039,12 @@ static int dax_iomap_pfn(const struct iomap *iomap, loff_t pos, size_t size,
 	if (length > 1 && !pfn_t_devmap(*pfnp))
 		goto out;
 	rc = 0;
+
+out_check_addr:
+	if (!kaddr)
+		goto out;
+	if (!*kaddr)
+		rc = -EFAULT;
 out:
 	dax_read_unlock(id);
 	return rc;
@@ -1401,7 +1409,7 @@ static vm_fault_t dax_fault_iter(struct vm_fault *vmf,
 		return pmd ? VM_FAULT_FALLBACK : VM_FAULT_SIGBUS;
 	}
 
-	err = dax_iomap_pfn(&iter->iomap, pos, size, &pfn);
+	err = dax_iomap_direct_access(&iter->iomap, pos, size, NULL, &pfn);
 	if (err)
 		return pmd ? VM_FAULT_FALLBACK : dax_fault_return(err);
 
-- 
2.32.0