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[62.64.249.96]) by smtp.gmail.com with ESMTPSA id k23-v6sm15476332wrd.85.2018.10.17.05.34.27 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 17 Oct 2018 05:34:27 -0700 (PDT) Date: Wed, 17 Oct 2018 13:34:26 +0100 From: Phillip Potter To: dushistov@mail.ru, David.Laight@aculab.com Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: [PATCH] fs: ufs: Remove switch statement from ufs_set_de_type function Message-ID: <20181017123426.GA17296@pathfinder> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Remove switch statement from ufs_set_de_type function in fs/ufs/util.h header and replace with simple assignment. For each case, S_IFx >> 12 is equal to DT_x, so in valid cases (mode & S_IFMT) >> 12 should give us the correct file type. This is verified at compile-time with BUILD_BUG_ON macro calls. For invalid cases, upper layer validation catches this anyway, so this improves readability and arguably performance by assigning (mode & S_IFMT) >> 12 directly. Signed-off-by: Phillip Potter --- fs/ufs/util.h | 39 +++++++++++---------------------------- 1 file changed, 11 insertions(+), 28 deletions(-) diff --git a/fs/ufs/util.h b/fs/ufs/util.h index 1fd3011ea623..dcf86829edc2 100644 --- a/fs/ufs/util.h +++ b/fs/ufs/util.h @@ -16,6 +16,7 @@ * some useful macros */ #define in_range(b,first,len) ((b)>=(first)&&(b)<(first)+(len)) +#define S_SHIFT 12 /* * functions used for retyping @@ -158,34 +159,16 @@ ufs_set_de_type(struct super_block *sb, struct ufs_dir_entry *de, int mode) if ((UFS_SB(sb)->s_flags & UFS_DE_MASK) != UFS_DE_44BSD) return; - /* - * TODO turn this into a table lookup - */ - switch (mode & S_IFMT) { - case S_IFSOCK: - de->d_u.d_44.d_type = DT_SOCK; - break; - case S_IFLNK: - de->d_u.d_44.d_type = DT_LNK; - break; - case S_IFREG: - de->d_u.d_44.d_type = DT_REG; - break; - case S_IFBLK: - de->d_u.d_44.d_type = DT_BLK; - break; - case S_IFDIR: - de->d_u.d_44.d_type = DT_DIR; - break; - case S_IFCHR: - de->d_u.d_44.d_type = DT_CHR; - break; - case S_IFIFO: - de->d_u.d_44.d_type = DT_FIFO; - break; - default: - de->d_u.d_44.d_type = DT_UNKNOWN; - } + /* Compile-time assertions that S_IFx >> S_SHIFT == DT_x */ + BUILD_BUG_ON(S_IFIFO >> S_SHIFT != DT_FIFO); + BUILD_BUG_ON(S_IFCHR >> S_SHIFT != DT_CHR); + BUILD_BUG_ON(S_IFDIR >> S_SHIFT != DT_DIR); + BUILD_BUG_ON(S_IFBLK >> S_SHIFT != DT_BLK); + BUILD_BUG_ON(S_IFREG >> S_SHIFT != DT_REG); + BUILD_BUG_ON(S_IFLNK >> S_SHIFT != DT_LNK); + BUILD_BUG_ON(S_IFSOCK >> S_SHIFT != DT_SOCK); + + de->d_u.d_44.d_type = (mode & S_IFMT) >> S_SHIFT; } static inline u32 -- 2.17.2