linux-kernel - [PATCH v3 4/6] gfs2: Replace kmap_atomic() by kmap_local

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Message-ID: <4817527acb9e015b3c6929517993ea50ba3427ad.1688073459.git.drv@mailo.com>
Date:   Fri, 30 Jun 2023 03:21:17 +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 v3 4/6] gfs2: Replace kmap_atomic() by kmap_local_page() in
 lops.c

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

Therefore, replace kmap_atomic() with kmap_local_page() in following
functions of lops.c:
   - gfs2_jhead_pg_srch()
   - gfs2_check_magic()
   - gfs2_before_commit()

kmap_atomic() disables page-faults and preemption (the latter only for
!PREEMPT_RT kernels), However, the code within the mapping/un-mapping in
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()).

Suggested-by: Fabio M. De Francesco <fmdefrancesco@...il.com>
Signed-off-by: Deepak R Varma <drv@...lo.com>
---
Changes in v3:
   - Patch included in patch series

Changes in v2:
   - None


 fs/gfs2/lops.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
index 1902413d5d12..a7c2296cb3c6 100644
--- a/fs/gfs2/lops.c
+++ b/fs/gfs2/lops.c
@@ -427,7 +427,7 @@ static bool gfs2_jhead_pg_srch(struct gfs2_jdesc *jd,
 {
 	struct gfs2_sbd *sdp = GFS2_SB(jd->jd_inode);
 	struct gfs2_log_header_host lh;
-	void *kaddr = kmap_atomic(page);
+	void *kaddr = kmap_local_page(page);
 	unsigned int offset;
 	bool ret = false;
 
@@ -441,7 +441,7 @@ static bool gfs2_jhead_pg_srch(struct gfs2_jdesc *jd,
 			}
 		}
 	}
-	kunmap_atomic(kaddr);
+	kunmap_local(kaddr);
 	return ret;
 }
 
@@ -626,11 +626,11 @@ static void gfs2_check_magic(struct buffer_head *bh)
 	__be32 *ptr;
 
 	clear_buffer_escaped(bh);
-	kaddr = kmap_atomic(bh->b_page);
+	kaddr = kmap_local_page(bh->b_page);
 	ptr = kaddr + bh_offset(bh);
 	if (*ptr == cpu_to_be32(GFS2_MAGIC))
 		set_buffer_escaped(bh);
-	kunmap_atomic(kaddr);
+	kunmap_local(kaddr);
 }
 
 static int blocknr_cmp(void *priv, const struct list_head *a,
@@ -699,10 +699,10 @@ static void gfs2_before_commit(struct gfs2_sbd *sdp, unsigned int limit,
 				void *kaddr;
 				page = mempool_alloc(gfs2_page_pool, GFP_NOIO);
 				ptr = page_address(page);
-				kaddr = kmap_atomic(bd2->bd_bh->b_page);
+				kaddr = kmap_local_page(bd2->bd_bh->b_page);
 				memcpy(ptr, kaddr + bh_offset(bd2->bd_bh),
 				       bd2->bd_bh->b_size);
-				kunmap_atomic(kaddr);
+				kunmap_local(kaddr);
 				*(__be32 *)ptr = 0;
 				clear_buffer_escaped(bd2->bd_bh);
 				unlock_buffer(bd2->bd_bh);
-- 
2.34.1