linux-kernel - [RFC][PATCH v2 05/10] exofs: use common file type conversion

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Date:   Tue, 23 Oct 2018 21:19:59 +0100
From:   Phillip Potter <phil@...lpotter.co.uk>
To:     ooo@...ctrozaur.com
Cc:     linux-kernel@...r.kernel.org, amir73il@...il.com,
        viro@...iv.linux.org.uk, linux-fsdevel@...r.kernel.org
Subject: [RFC][PATCH v2 05/10] exofs: use common file type conversion

Deduplicate the exofs file type conversion implementation.

Original patch by Amir Goldstein.

v2:
- This version does not remove EXOFS_FT_x enum from fs/exofs/common.h,
  as these values are now used in compile-time checks added by
  Phillip Potter to make sure they remain the same as FT_x values

v1:
- Initial implementation

Signed-off-by: Phillip Potter <phil@...lpotter.co.uk>
---
 fs/exofs/dir.c | 49 ++++++++++++++++++-------------------------------
 1 file changed, 18 insertions(+), 31 deletions(-)

diff --git a/fs/exofs/dir.c b/fs/exofs/dir.c
index f0138674c1ed..2e3161ca9014 100644
--- a/fs/exofs/dir.c
+++ b/fs/exofs/dir.c
@@ -204,33 +204,10 @@ exofs_validate_entry(char *base, unsigned offset, unsigned mask)
 	return (char *)p - base;
 }
 
-static unsigned char exofs_filetype_table[EXOFS_FT_MAX] = {
-	[EXOFS_FT_UNKNOWN]	= DT_UNKNOWN,
-	[EXOFS_FT_REG_FILE]	= DT_REG,
-	[EXOFS_FT_DIR]		= DT_DIR,
-	[EXOFS_FT_CHRDEV]	= DT_CHR,
-	[EXOFS_FT_BLKDEV]	= DT_BLK,
-	[EXOFS_FT_FIFO]		= DT_FIFO,
-	[EXOFS_FT_SOCK]		= DT_SOCK,
-	[EXOFS_FT_SYMLINK]	= DT_LNK,
-};
-
-#define S_SHIFT 12
-static unsigned char exofs_type_by_mode[S_IFMT >> S_SHIFT] = {
-	[S_IFREG >> S_SHIFT]	= EXOFS_FT_REG_FILE,
-	[S_IFDIR >> S_SHIFT]	= EXOFS_FT_DIR,
-	[S_IFCHR >> S_SHIFT]	= EXOFS_FT_CHRDEV,
-	[S_IFBLK >> S_SHIFT]	= EXOFS_FT_BLKDEV,
-	[S_IFIFO >> S_SHIFT]	= EXOFS_FT_FIFO,
-	[S_IFSOCK >> S_SHIFT]	= EXOFS_FT_SOCK,
-	[S_IFLNK >> S_SHIFT]	= EXOFS_FT_SYMLINK,
-};
-
 static inline
 void exofs_set_de_type(struct exofs_dir_entry *de, struct inode *inode)
 {
-	umode_t mode = inode->i_mode;
-	de->file_type = exofs_type_by_mode[(mode & S_IFMT) >> S_SHIFT];
+	de->file_type = fs_umode_to_ftype(inode->i_mode);
 }
 
 static int
@@ -279,17 +256,27 @@ exofs_readdir(struct file *file, struct dir_context *ctx)
 				exofs_put_page(page);
 				return -EIO;
 			}
-			if (de->inode_no) {
-				unsigned char t;
 
-				if (de->file_type < EXOFS_FT_MAX)
-					t = exofs_filetype_table[de->file_type];
-				else
-					t = DT_UNKNOWN;
+			/*
+			 * compile-time asserts that generic FT_x types
+			 * still match EXOFS_FT_x types - no need to list
+			 * for other functions as well as build will
+			 * fail either way
+			 */
+			BUILD_BUG_ON(EXOFS_FT_UNKNOWN != FT_UNKNOWN);
+			BUILD_BUG_ON(EXOFS_FT_REG_FILE != FT_REG_FILE);
+			BUILD_BUG_ON(EXOFS_FT_DIR != FT_DIR);
+			BUILD_BUG_ON(EXOFS_FT_CHRDEV != FT_CHRDEV);
+			BUILD_BUG_ON(EXOFS_FT_BLKDEV != FT_BLKDEV);
+			BUILD_BUG_ON(EXOFS_FT_FIFO != FT_FIFO);
+			BUILD_BUG_ON(EXOFS_FT_SOCK != FT_SOCK);
+			BUILD_BUG_ON(EXOFS_FT_SYMLINK != FT_SYMLINK);
+			BUILD_BUG_ON(EXOFS_FT_MAX != FT_MAX);
 
+			if (de->inode_no) {
 				if (!dir_emit(ctx, de->name, de->name_len,
 						le64_to_cpu(de->inode_no),
-						t)) {
+						fs_dtype(de->file_type))) {
 					exofs_put_page(page);
 					return 0;
 				}
-- 
2.17.2