linux-kernel - [PATCH] erofs: refine erofs_iomap

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Message-ID: <20250716092254.3826715-1-hsiangkao@linux.alibaba.com>
Date: Wed, 16 Jul 2025 17:22:54 +0800
From: Gao Xiang <hsiangkao@...ux.alibaba.com>
To: linux-erofs@...ts.ozlabs.org
Cc: LKML <linux-kernel@...r.kernel.org>,
	Gao Xiang <hsiangkao@...ux.alibaba.com>
Subject: [PATCH] erofs: refine erofs_iomap_begin()

 - Avoid calling erofs_map_dev() for unmapped extents;

 - Assign `iomap->addr` for inline extents too (since they have physical
   location).

Signed-off-by: Gao Xiang <hsiangkao@...ux.alibaba.com>
---
 fs/erofs/data.c | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/fs/erofs/data.c b/fs/erofs/data.c
index dd7d86809c18..383c1337e157 100644
--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -269,6 +269,16 @@ static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 	if (ret < 0)
 		return ret;
 
+	iomap->offset = map.m_la;
+	iomap->length = map.m_llen;
+	iomap->flags = 0;
+	iomap->private = NULL;
+	if (!(map.m_flags & EROFS_MAP_MAPPED)) {
+		iomap->type = IOMAP_HOLE;
+		iomap->addr = IOMAP_NULL_ADDR;
+		return 0;
+	}
+
 	mdev = (struct erofs_map_dev) {
 		.m_deviceid = map.m_deviceid,
 		.m_pa = map.m_pa,
@@ -277,22 +287,14 @@ static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 	if (ret)
 		return ret;
 
-	iomap->offset = map.m_la;
 	if (flags & IOMAP_DAX)
 		iomap->dax_dev = mdev.m_dif->dax_dev;
 	else
 		iomap->bdev = mdev.m_bdev;
-	iomap->length = map.m_llen;
-	iomap->flags = 0;
-	iomap->private = NULL;
 
-	if (!(map.m_flags & EROFS_MAP_MAPPED)) {
-		iomap->type = IOMAP_HOLE;
-		iomap->addr = IOMAP_NULL_ADDR;
-		if (!iomap->length)
-			iomap->length = length;
-		return 0;
-	}
+	iomap->addr = mdev.m_dif->fsoff + mdev.m_pa;
+	if (flags & IOMAP_DAX)
+		iomap->addr += mdev.m_dif->dax_part_off;
 
 	if (map.m_flags & EROFS_MAP_META) {
 		void *ptr;
@@ -306,9 +308,6 @@ static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 		iomap->private = buf.base;
 	} else {
 		iomap->type = IOMAP_MAPPED;
-		iomap->addr = mdev.m_dif->fsoff + mdev.m_pa;
-		if (flags & IOMAP_DAX)
-			iomap->addr += mdev.m_dif->dax_part_off;
 	}
 	return 0;
 }
-- 
2.43.5