linux-kernel - [PATCH] ecryptfs: Replace kmap() with kmap_local

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Date:   Mon,  4 Jul 2022 18:23:43 +0200
From:   "Fabio M. De Francesco" <fmdefrancesco@...il.com>
To:     Tyler Hicks <code@...icks.com>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Damien Le Moal <damien.lemoal@...nsource.wdc.com>,
        Seth Forshee <sforshee@...italocean.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        "Fabio M. De Francesco" <fmdefrancesco@...il.com>,
        Christian Brauner <brauner@...nel.org>,
        Muchun Song <songmuchun@...edance.com>,
        ecryptfs@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Ira Weiny <ira.weiny@...el.com>
Subject: [PATCH] ecryptfs: Replace kmap() with kmap_local_page()

The use of kmap() is being deprecated in favor of kmap_local_page().

With kmap_local_page() the mappings are per thread, CPU local and not
globally visible.

Use kmap_local_page() on all calling sites where kmap() is currently used.

Suggested-by: Ira Weiny <ira.weiny@...el.com>
Reviewed-by: Ira Weiny <ira.weiny@...el.com>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@...il.com>
---

Please discard RFC PATCH at
https://lore.kernel.org/lkml/20220628184950.2045-1-fmdefrancesco@gmail.com/

 fs/ecryptfs/crypto.c     | 8 ++++----
 fs/ecryptfs/read_write.c | 8 ++++----
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index e3f5d7f3c8a0..03263ebcccc6 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -465,10 +465,10 @@ int ecryptfs_encrypt_page(struct page *page)
 	}
 
 	lower_offset = lower_offset_for_page(crypt_stat, page);
-	enc_extent_virt = kmap(enc_extent_page);
+	enc_extent_virt = kmap_local_page(enc_extent_page);
 	rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset,
 				  PAGE_SIZE);
-	kunmap(enc_extent_page);
+	kunmap_local(enc_extent_virt);
 	if (rc < 0) {
 		ecryptfs_printk(KERN_ERR,
 			"Error attempting to write lower page; rc = [%d]\n",
@@ -514,10 +514,10 @@ int ecryptfs_decrypt_page(struct page *page)
 	BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
 
 	lower_offset = lower_offset_for_page(crypt_stat, page);
-	page_virt = kmap(page);
+	page_virt = kmap_local_page(page);
 	rc = ecryptfs_read_lower(page_virt, lower_offset, PAGE_SIZE,
 				 ecryptfs_inode);
-	kunmap(page);
+	kunmap_local(page_virt);
 	if (rc < 0) {
 		ecryptfs_printk(KERN_ERR,
 			"Error attempting to read lower page; rc = [%d]\n",
diff --git a/fs/ecryptfs/read_write.c b/fs/ecryptfs/read_write.c
index 60bdcaddcbe5..5edf027c8359 100644
--- a/fs/ecryptfs/read_write.c
+++ b/fs/ecryptfs/read_write.c
@@ -64,11 +64,11 @@ int ecryptfs_write_lower_page_segment(struct inode *ecryptfs_inode,
 
 	offset = ((((loff_t)page_for_lower->index) << PAGE_SHIFT)
 		  + offset_in_page);
-	virt = kmap(page_for_lower);
+	virt = kmap_local_page(page_for_lower);
 	rc = ecryptfs_write_lower(ecryptfs_inode, virt, offset, size);
 	if (rc > 0)
 		rc = 0;
-	kunmap(page_for_lower);
+	kunmap_local(virt);
 	return rc;
 }
 
@@ -253,11 +253,11 @@ int ecryptfs_read_lower_page_segment(struct page *page_for_ecryptfs,
 	int rc;
 
 	offset = ((((loff_t)page_index) << PAGE_SHIFT) + offset_in_page);
-	virt = kmap(page_for_ecryptfs);
+	virt = kmap_local_page(page_for_ecryptfs);
 	rc = ecryptfs_read_lower(virt, offset, size, ecryptfs_inode);
 	if (rc > 0)
 		rc = 0;
-	kunmap(page_for_ecryptfs);
+	kunmap_local(virt);
 	flush_dcache_page(page_for_ecryptfs);
 	return rc;
 }
-- 
2.36.1