linux-kernel - [PATCH v2] gfs2: Replace deprecated kmap_atomic() by kmap_local

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Message-ID: <ZJk1XTtgLFxIcxzp@bu2204.myguest.virtualbox.org>
Date:   Mon, 26 Jun 2023 12:21:09 +0530
From:   Deepak R Varma <drv@...lo.com>
To:     Bob Peterson <rpeterso@...hat.com>,
        Andreas Gruenbacher <agruenba@...hat.com>,
        cluster-devel@...hat.com, linux-kernel@...r.kernel.org
Cc:     Ira Weiny <ira.weiny@...el.com>,
        "Fabio M. De Francesco" <fmdefrancesco@...il.com>,
        Sumitra Sharma <sumitraartsy@...il.com>,
        Deepak R Varma <drv@...lo.com>
Subject: [PATCH v2] gfs2: Replace deprecated kmap_atomic() by
 kmap_local_page()

kmap_atomic() is deprecated in favor of kmap_local_{folio,page}().

Therefore, replace kmap_atomic() with kmap_local_page() in
gfs2_internal_read() and stuffed_readpage().

kmap_atomic() disables page-faults and preemption (the latter only for
!PREEMPT_RT kernels), However, the code within the mapping/un-mapping in
gfs2_internal_read() and stuffed_readpage() does not depend on the
above-mentioned side effects.

Therefore, a mere replacement of the old API with the new one is all that
is required (i.e., there is no need to explicitly add any calls to
pagefault_disable() and/or preempt_disable()).

Signed-off-by: Deepak R Varma <drv@...lo.com>
---
Note: The Patch is build tested only. I will be happy to run recommended testing
with some guidance if required.

Changes in v2:
   - Update patch description to correct the replacement function name from
     kmap_local_folio to kmap_local _page 


 fs/gfs2/aops.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/gfs2/aops.c b/fs/gfs2/aops.c
index 3b41542d6697..7bd92054d353 100644
--- a/fs/gfs2/aops.c
+++ b/fs/gfs2/aops.c
@@ -432,10 +432,10 @@ static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
 	if (error)
 		return error;
 
-	kaddr = kmap_atomic(page);
+	kaddr = kmap_local_page(page);
 	memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode), dsize);
 	memset(kaddr + dsize, 0, PAGE_SIZE - dsize);
-	kunmap_atomic(kaddr);
+	kunmap_local(kaddr);
 	flush_dcache_page(page);
 	brelse(dibh);
 	SetPageUptodate(page);
@@ -498,12 +498,12 @@ int gfs2_internal_read(struct gfs2_inode *ip, char *buf, loff_t *pos,
 				continue;
 			return PTR_ERR(page);
 		}
-		p = kmap_atomic(page);
+		p = kmap_local_page(page);
 		amt = size - copied;
 		if (offset + size > PAGE_SIZE)
 			amt = PAGE_SIZE - offset;
 		memcpy(buf + copied, p + offset, amt);
-		kunmap_atomic(p);
+		kunmap_local(p);
 		put_page(page);
 		copied += amt;
 		index++;
-- 
2.34.1