linux-kernel - [PATCH mmotm] nilfs2: fix wrong counting of checkpoints and dirty segments

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Date:	Mon,  2 Feb 2009 21:26:27 +0900
From:	Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>
Subject: [PATCH mmotm] nilfs2: fix wrong counting of checkpoints and dirty segments

Reinoud Zandijk found that counters for the number of checkpoints and
the number of dirty segments go wrong after a garbage collection.

This problem turns out to be a bug of counter operations using
le64_cpu_add() with a negative variable like:

  le64_cpu_add(&counter, -n);

where the variable n was not u64.

This fixes the problem by casting the delta to (u64).

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>
---
 fs/nilfs2/cpfile.c |    2 +-
 fs/nilfs2/sufile.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/nilfs2/cpfile.c b/fs/nilfs2/cpfile.c
index 3ac0bb4..a4c9550 100644
--- a/fs/nilfs2/cpfile.c
+++ b/fs/nilfs2/cpfile.c
@@ -357,7 +357,7 @@ int nilfs_cpfile_delete_checkpoints(struct inode *cpfile,
 		kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
 		header = nilfs_cpfile_block_get_header(cpfile, header_bh,
 						       kaddr);
-		le64_add_cpu(&header->ch_ncheckpoints, -tnicps);
+		le64_add_cpu(&header->ch_ncheckpoints, -(u64)tnicps);
 		nilfs_mdt_mark_buffer_dirty(header_bh);
 		nilfs_mdt_mark_dirty(cpfile);
 		kunmap_atomic(kaddr, KM_USER0);
diff --git a/fs/nilfs2/sufile.c b/fs/nilfs2/sufile.c
index d672924..b3674a8 100644
--- a/fs/nilfs2/sufile.c
+++ b/fs/nilfs2/sufile.c
@@ -325,7 +325,7 @@ int nilfs_sufile_freev(struct inode *sufile, __u64 *segnum, size_t nsegs)
 	kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
 	header = nilfs_sufile_block_get_header(sufile, header_bh, kaddr);
 	le64_add_cpu(&header->sh_ncleansegs, nsegs);
-	le64_add_cpu(&header->sh_ndirtysegs, -nsegs);
+	le64_add_cpu(&header->sh_ndirtysegs, -(u64)nsegs);
 	kunmap_atomic(kaddr, KM_USER0);
 	nilfs_mdt_mark_buffer_dirty(header_bh);
 	nilfs_mdt_mark_dirty(sufile);
-- 
1.5.6.5

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