linux-kernel - [PATCH 01/11] btrfs: add macros for compression type and level

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Date:   Mon, 28 Jan 2019 16:24:27 -0500
From:   Dennis Zhou <dennis@...nel.org>
To:     David Sterba <dsterba@...e.com>,
        Josef Bacik <josef@...icpanda.com>, Chris Mason <clm@...com>,
        Omar Sandoval <osandov@...ndov.com>,
        Nick Terrell <terrelln@...com>
Cc:     kernel-team@...com, linux-btrfs@...r.kernel.org,
        linux-kernel@...r.kernel.org, Dennis Zhou <dennis@...nel.org>
Subject: [PATCH 01/11] btrfs: add macros for compression type and level

It is very easy to miss places that rely on a certain bitshifting for
decyphering the type_level overloading. Make macros handle this instead.

Signed-off-by: Dennis Zhou <dennis@...nel.org>
---
 fs/btrfs/compression.c | 2 +-
 fs/btrfs/compression.h | 3 +++
 fs/btrfs/zlib.c        | 2 +-
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 548057630b69..586f95ac0aea 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -1036,9 +1036,9 @@ int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping,
 			 unsigned long *total_in,
 			 unsigned long *total_out)
 {
+	int type = BTRFS_COMPRESS_TYPE(type_level);
 	struct list_head *workspace;
 	int ret;
-	int type = type_level & 0xF;
 
 	workspace = find_workspace(type);
 
diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
index ddda9b80bf20..69a9197dadc3 100644
--- a/fs/btrfs/compression.h
+++ b/fs/btrfs/compression.h
@@ -25,6 +25,9 @@
 
 #define	BTRFS_ZLIB_DEFAULT_LEVEL		3
 
+#define BTRFS_COMPRESS_TYPE(type_level)		(type_level & 0xF)
+#define BTRFS_COMPRESS_LEVEL(type_level)	((type_level & 0xF0) >> 4)
+
 struct compressed_bio {
 	/* number of bios pending for this compressed extent */
 	refcount_t pending_bios;
diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
index 970ff3e35bb3..1480b3eee306 100644
--- a/fs/btrfs/zlib.c
+++ b/fs/btrfs/zlib.c
@@ -393,7 +393,7 @@ static int zlib_decompress(struct list_head *ws, unsigned char *data_in,
 static void zlib_set_level(struct list_head *ws, unsigned int type)
 {
 	struct workspace *workspace = list_entry(ws, struct workspace, list);
-	unsigned level = (type & 0xF0) >> 4;
+	unsigned int level = BTRFS_COMPRESS_LEVEL(type);
 
 	if (level > 9)
 		level = 9;
-- 
2.17.1