linux-kernel - [PATCH 2/4] befs: add check for ag

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Date:	Tue,  9 Aug 2016 23:01:24 +0100
From:	Luis de Bethencourt <luisbg@....samsung.com>
To:	linux-kernel@...r.kernel.org
Cc:	akpm@...ux-foundation.org, viro@...iv.linux.org.uk,
	salah.triki@....org, Luis de Bethencourt <luisbg@....samsung.com>
Subject: [PATCH 2/4] befs: add check for ag_shift in superblock

ag_shift and blocks_per_ag contain the same information in different ways,
same as block_shift and block_size do. It is worth checking this two are
consistent, but since blocks_per_ag isn't documented as mandatory to use
some implementations of befs don't enforce this, so making it non-fatal if
they don't match and just having it as a warning.

Signed-off-by: Luis de Bethencourt <luisbg@....samsung.com>
---
 fs/befs/super.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/befs/super.c b/fs/befs/super.c
index dc13df8..c36745d 100644
--- a/fs/befs/super.c
+++ b/fs/befs/super.c
@@ -103,6 +103,13 @@ befs_check_sb(struct super_block *sb)
 		return BEFS_ERR;
 	}
 
+
+	/* ag_shift also encodes the same information as blocks_per_ag in a
+	 * different way, non-fatal consistency check
+	 */
+	if ((1 << befs_sb->ag_shift) != befs_sb->blocks_per_ag)
+		befs_error(sb, "ag_shift disagrees with blocks_per_ag.");
+
 	if (befs_sb->log_start != befs_sb->log_end || befs_sb->flags == BEFS_DIRTY) {
 		befs_error(sb, "Filesystem not clean! There are blocks in the "
 			   "journal. You must boot into BeOS and mount this volume "
-- 
2.5.1