[PATCH v5] xfs: fix the size of xfs_mode_to_ftype table

[Amir Goldstein <amir73il@gmail.com>]

Fix the size of the xfs_mode_to_ftype conversion table,
which was too small to handle an invalid value of mode=S_IFMT.

Use a convenience macro S_DT(mode) to convert from
mode to dirent file type and change the name of the table
to xfs_dtype_to_ftype to correctly describe its index values.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 fs/xfs/libxfs/xfs_dir2.c | 18 +++++++++---------
 fs/xfs/libxfs/xfs_dir2.h |  4 +++-
 fs/xfs/xfs_iops.c        |  2 +-
 3 files changed, 13 insertions(+), 11 deletions(-)

Darrick,

I implemented the xfs specific test case to test all possible
malformed file type values as you suggested and fixed up some minor
nits that Brian pointed out.

Tested with generic/396 with -n ftype=0|1.
Tested with new xfs/348 test with -n ftype=0|1.

Amir.

v5:
- remove wrong argument about on-disk malformed mode from commit message
- address Brian's review comments

v4:
- independent fix patch for xfs

v3:
- resort to simpler cleanup with macros DT_MAX and S_DT()
- mention the minor bug fix in commit message

v2:
- add private conversion from common to on-disk values

v1:
- use common conversion functions to get on-disk values

diff --git a/fs/xfs/libxfs/xfs_dir2.c b/fs/xfs/libxfs/xfs_dir2.c
index c58d72c..48d7c45 100644
--- a/fs/xfs/libxfs/xfs_dir2.c
+++ b/fs/xfs/libxfs/xfs_dir2.c
@@ -41,15 +41,15 @@ struct xfs_name xfs_name_dotdot = { (unsigned char *)"..", 2, XFS_DIR3_FT_DIR };
  * for file type specification. This will be propagated into the directory
  * structure if appropriate for the given operation and filesystem config.
  */
-const unsigned char xfs_mode_to_ftype[S_IFMT >> S_SHIFT] = {
-	[0]			= XFS_DIR3_FT_UNKNOWN,
-	[S_IFREG >> S_SHIFT]    = XFS_DIR3_FT_REG_FILE,
-	[S_IFDIR >> S_SHIFT]    = XFS_DIR3_FT_DIR,
-	[S_IFCHR >> S_SHIFT]    = XFS_DIR3_FT_CHRDEV,
-	[S_IFBLK >> S_SHIFT]    = XFS_DIR3_FT_BLKDEV,
-	[S_IFIFO >> S_SHIFT]    = XFS_DIR3_FT_FIFO,
-	[S_IFSOCK >> S_SHIFT]   = XFS_DIR3_FT_SOCK,
-	[S_IFLNK >> S_SHIFT]    = XFS_DIR3_FT_SYMLINK,
+const unsigned char xfs_dtype_to_ftype[S_DT_MAX+1] = {
+	[0]                = XFS_DIR3_FT_UNKNOWN,
+	[S_DT(S_IFREG)]    = XFS_DIR3_FT_REG_FILE,
+	[S_DT(S_IFDIR)]    = XFS_DIR3_FT_DIR,
+	[S_DT(S_IFCHR)]    = XFS_DIR3_FT_CHRDEV,
+	[S_DT(S_IFBLK)]    = XFS_DIR3_FT_BLKDEV,
+	[S_DT(S_IFIFO)]    = XFS_DIR3_FT_FIFO,
+	[S_DT(S_IFSOCK)]   = XFS_DIR3_FT_SOCK,
+	[S_DT(S_IFLNK)]    = XFS_DIR3_FT_SYMLINK,
 };
 
 /*
diff --git a/fs/xfs/libxfs/xfs_dir2.h b/fs/xfs/libxfs/xfs_dir2.h
index 0197590..4934d38 100644
--- a/fs/xfs/libxfs/xfs_dir2.h
+++ b/fs/xfs/libxfs/xfs_dir2.h
@@ -35,7 +35,9 @@ extern struct xfs_name	xfs_name_dotdot;
  * directory filetype conversion tables.
  */
 #define S_SHIFT 12
-extern const unsigned char xfs_mode_to_ftype[];
+#define S_DT(mode)     (((mode) & S_IFMT) >> S_SHIFT)
+#define S_DT_MAX       S_DT(S_IFMT)
+extern const unsigned char xfs_dtype_to_ftype[];
 
 /*
  * directory operations vector for encode/decode routines
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 308bebb..d2da9ca 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -103,7 +103,7 @@ xfs_dentry_to_name(
 {
 	namep->name = dentry->d_name.name;
 	namep->len = dentry->d_name.len;
-	namep->type = xfs_mode_to_ftype[(mode & S_IFMT) >> S_SHIFT];
+	namep->type = xfs_dtype_to_ftype[S_DT(mode)];
 }
 
 STATIC void
-- 
2.7.4