linux-kernel - [PATCH] zonefs: Call page_address() on page acquired with GFP

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Date:   Tue,  5 Jul 2022 16:22:02 +0200
From:   "Fabio M. De Francesco" <fmdefrancesco@...il.com>
To:     Damien Le Moal <damien.lemoal@...nsource.wdc.com>,
        Naohiro Aota <naohiro.aota@....com>,
        Johannes Thumshirn <jth@...nel.org>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     "Fabio M. De Francesco" <fmdefrancesco@...il.com>,
        Ira Weiny <ira.weiny@...el.com>
Subject: [PATCH] zonefs: Call page_address() on page acquired with GFP_KERNEL flag

zonefs_read_super() acquires a page with alloc_page(GFP_KERNEL). That
page cannot come from ZONE_HIGHMEM, thus there's no need to map it with
kmap().

Therefore, use a plain page_address() on that page.

Suggested-by: Ira Weiny <ira.weiny@...el.com>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@...il.com>
---
 fs/zonefs/super.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/fs/zonefs/super.c b/fs/zonefs/super.c
index 053299758deb..bd4e4be97a68 100644
--- a/fs/zonefs/super.c
+++ b/fs/zonefs/super.c
@@ -1687,11 +1687,11 @@ static int zonefs_read_super(struct super_block *sb)
 	if (ret)
 		goto free_page;
 
-	super = kmap(page);
+	super = page_address(page);
 
 	ret = -EINVAL;
 	if (le32_to_cpu(super->s_magic) != ZONEFS_MAGIC)
-		goto unmap;
+		goto free_page;
 
 	stored_crc = le32_to_cpu(super->s_crc);
 	super->s_crc = 0;
@@ -1699,14 +1699,14 @@ static int zonefs_read_super(struct super_block *sb)
 	if (crc != stored_crc) {
 		zonefs_err(sb, "Invalid checksum (Expected 0x%08x, got 0x%08x)",
 			   crc, stored_crc);
-		goto unmap;
+		goto free_page;
 	}
 
 	sbi->s_features = le64_to_cpu(super->s_features);
 	if (sbi->s_features & ~ZONEFS_F_DEFINED_FEATURES) {
 		zonefs_err(sb, "Unknown features set 0x%llx\n",
 			   sbi->s_features);
-		goto unmap;
+		goto free_page;
 	}
 
 	if (sbi->s_features & ZONEFS_F_UID) {
@@ -1714,7 +1714,7 @@ static int zonefs_read_super(struct super_block *sb)
 				       le32_to_cpu(super->s_uid));
 		if (!uid_valid(sbi->s_uid)) {
 			zonefs_err(sb, "Invalid UID feature\n");
-			goto unmap;
+			goto free_page;
 		}
 	}
 
@@ -1723,7 +1723,7 @@ static int zonefs_read_super(struct super_block *sb)
 				       le32_to_cpu(super->s_gid));
 		if (!gid_valid(sbi->s_gid)) {
 			zonefs_err(sb, "Invalid GID feature\n");
-			goto unmap;
+			goto free_page;
 		}
 	}
 
@@ -1732,14 +1732,12 @@ static int zonefs_read_super(struct super_block *sb)
 
 	if (memchr_inv(super->s_reserved, 0, sizeof(super->s_reserved))) {
 		zonefs_err(sb, "Reserved area is being used\n");
-		goto unmap;
+		goto free_page;
 	}
 
 	import_uuid(&sbi->s_uuid, super->s_uuid);
 	ret = 0;
 
-unmap:
-	kunmap(page);
 free_page:
 	__free_page(page);
 
-- 
2.36.1