VFS: Add a whiteout dentry type

Add DCACHE_WHITEOUT_TYPE and provide a d_is_whiteout() accessor function.  A
d_is_miss() accessor is also added for ordinary cache misses and
d_is_negative() is modified to indicate either an ordinary miss or an enforced
miss (whiteout).

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 047c0db..98d2a94 100644 (file)
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -215,11 +215,12 @@ struct dentry_operations {
 #define DCACHE_LRU_LIST                        0x00080000
 
 #define DCACHE_ENTRY_TYPE              0x00700000
-#define DCACHE_MISS_TYPE               0x00000000 /* Negative dentry */
-#define DCACHE_DIRECTORY_TYPE          0x00100000 /* Normal directory */
-#define DCACHE_AUTODIR_TYPE            0x00200000 /* Lookupless directory (presumed automount) */
-#define DCACHE_SYMLINK_TYPE            0x00300000 /* Symlink */
-#define DCACHE_FILE_TYPE               0x00400000 /* Other file type */
+#define DCACHE_MISS_TYPE               0x00000000 /* Negative dentry (maybe fallthru to nowhere) */
+#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_MAY_FREE                        0x00800000
 
@@ -423,6 +424,16 @@ static inline unsigned __d_entry_type(const struct dentry *dentry)
        return dentry->d_flags & DCACHE_ENTRY_TYPE;
 }
 
+static inline bool d_is_miss(const struct dentry *dentry)
+{
+       return __d_entry_type(dentry) == DCACHE_MISS_TYPE;
+}
+
+static inline bool d_is_whiteout(const struct dentry *dentry)
+{
+       return __d_entry_type(dentry) == DCACHE_WHITEOUT_TYPE;
+}
+
 static inline bool d_can_lookup(const struct dentry *dentry)
 {
        return __d_entry_type(dentry) == DCACHE_DIRECTORY_TYPE;
@@ -450,7 +461,8 @@ static inline bool d_is_file(const struct dentry *dentry)
 
 static inline bool d_is_negative(const struct dentry *dentry)
 {
-       return __d_entry_type(dentry) == DCACHE_MISS_TYPE;
+       // TODO: check d_is_whiteout(dentry) also.
+       return d_is_miss(dentry);
 }
 
 static inline bool d_is_positive(const struct dentry *dentry)