linux-kernel - [PATCH] ntfs: don't disable interrupts during kmap

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Message-Id: <20180504144222.5443-1-bigeasy@linutronix.de>
Date:   Fri,  4 May 2018 16:42:22 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     linux-kernel@...r.kernel.org
Cc:     tglx@...utronix.de, linux-ntfs-dev@...ts.sourceforge.net,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Anton Altaparmakov <anton@...era.com>
Subject: [PATCH] ntfs: don't disable interrupts during kmap_atomic()

ntfs_end_buffer_async_read() disables interrupts around kmap_atomic(). This is
a leftover from the old kmap_atomic() implementation which relied on fixed
mapping slots, so the caller had to make sure that the same slot could not be
reused from an interrupting context.

kmap_atomic() was changed to dynamic slots long ago and commit 1ec9c5ddc17a
("include/linux/highmem.h: remove the second argument of k[un]map_atomic()")
removed the slot assignements, but the callers were not checked for now
redundant interrupt disabling.

Remove the conditional interrupt disable.

Cc: Anton Altaparmakov <anton@...era.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 fs/ntfs/aops.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/fs/ntfs/aops.c b/fs/ntfs/aops.c
index 3a2e509c77c5..01c770979921 100644
--- a/fs/ntfs/aops.c
+++ b/fs/ntfs/aops.c
@@ -93,13 +93,11 @@ static void ntfs_end_buffer_async_read(struct buffer_head *bh, int uptodate)
 			ofs = 0;
 			if (file_ofs < init_size)
 				ofs = init_size - file_ofs;
-			local_irq_save(flags);
 			kaddr = kmap_atomic(page);
 			memset(kaddr + bh_offset(bh) + ofs, 0,
 					bh->b_size - ofs);
 			flush_dcache_page(page);
 			kunmap_atomic(kaddr);
-			local_irq_restore(flags);
 		}
 	} else {
 		clear_buffer_uptodate(bh);
@@ -146,13 +144,11 @@ static void ntfs_end_buffer_async_read(struct buffer_head *bh, int uptodate)
 		recs = PAGE_SIZE / rec_size;
 		/* Should have been verified before we got here... */
 		BUG_ON(!recs);
-		local_irq_save(flags);
 		kaddr = kmap_atomic(page);
 		for (i = 0; i < recs; i++)
 			post_read_mst_fixup((NTFS_RECORD*)(kaddr +
 					i * rec_size), rec_size);
 		kunmap_atomic(kaddr);
-		local_irq_restore(flags);
 		flush_dcache_page(page);
 		if (likely(page_uptodate && !PageError(page)))
 			SetPageUptodate(page);
-- 
2.17.0