VFS: Split DCACHE_FILE_TYPE into regular and special types

Split DCACHE_FILE_TYPE into DCACHE_REGULAR_TYPE (dentries representing regular
files) and DCACHE_SPECIAL_TYPE (representing blockdev, chardev, FIFO and
socket files).

d_is_reg() and d_is_special() are added to detect these subtypes and
d_is_file() is left as the union of the two.

This allows a number of places that use S_ISREG(dentry->d_inode->i_mode) to
use d_is_reg(dentry) instead.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/dcache.c

@@ -1677,7 +1677,7 @@ EXPORT_SYMBOL(d_set_fallthru);
 
 static unsigned d_flags_for_inode(struct inode *inode)
 {
-	unsigned add_flags = DCACHE_FILE_TYPE;
+	unsigned add_flags = DCACHE_REGULAR_TYPE;
 
 	if (!inode)
 		return DCACHE_MISS_TYPE;
@@ -1690,13 +1690,21 @@ static unsigned d_flags_for_inode(struct inode *inode)
 			else
 				inode->i_opflags |= IOP_LOOKUP;
 		}
-	} else if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) {
-		if (unlikely(inode->i_op->follow_link))
+		goto type_determined;
+	}
+
+	if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) {
+		if (unlikely(inode->i_op->follow_link)) {
 			add_flags = DCACHE_SYMLINK_TYPE;
-		else
-			inode->i_opflags |= IOP_NOFOLLOW;
+			goto type_determined;
+		}
+		inode->i_opflags |= IOP_NOFOLLOW;
 	}
 
+	if (unlikely(!S_ISREG(inode->i_mode)))
+		add_flags = DCACHE_SPECIAL_TYPE;
+
+type_determined:
 	if (unlikely(IS_AUTOMOUNT(inode)))
 		add_flags |= DCACHE_NEED_AUTOMOUNT;
 	return add_flags;

include/linux/dcache.h

@@ -219,8 +219,9 @@ struct dentry_operations {
 #define DCACHE_WHITEOUT_TYPE		0x00100000 /* Whiteout dentry (stop pathwalk) */
 #define DCACHE_DIRECTORY_TYPE		0x00200000 /* Normal directory */
 #define DCACHE_AUTODIR_TYPE		0x00300000 /* Lookupless directory (presumed automount) */
-#define DCACHE_SYMLINK_TYPE		0x00400000 /* Symlink (or fallthru to such) */
-#define DCACHE_FILE_TYPE		0x00500000 /* Other file type (or fallthru to such) */
+#define DCACHE_REGULAR_TYPE		0x00400000 /* Regular file type (or fallthru to such) */
+#define DCACHE_SPECIAL_TYPE		0x00500000 /* Other file type (or fallthru to such) */
+#define DCACHE_SYMLINK_TYPE		0x00600000 /* Symlink (or fallthru to such) */
 
 #define DCACHE_MAY_FREE			0x00800000
 #define DCACHE_FALLTHRU			0x01000000 /* Fall through to lower layer */
@@ -455,9 +456,19 @@ static inline bool d_is_symlink(const struct dentry *dentry)
 	return __d_entry_type(dentry) == DCACHE_SYMLINK_TYPE;
 }
 
+static inline bool d_is_reg(const struct dentry *dentry)
+{
+	return __d_entry_type(dentry) == DCACHE_REGULAR_TYPE;
+}
+
+static inline bool d_is_special(const struct dentry *dentry)
+{
+	return __d_entry_type(dentry) == DCACHE_SPECIAL_TYPE;
+}
+
 static inline bool d_is_file(const struct dentry *dentry)
 {
-	return __d_entry_type(dentry) == DCACHE_FILE_TYPE;
+	return d_is_reg(dentry) || d_is_special(dentry);
 }
 
 static inline bool d_is_negative(const struct dentry *dentry)