aufs: finfo for directory

Expand finfo to support for a directory.
For readdir(3), see VDIR and RDU in later commits.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>

fs/aufs/file.h

@@ -22,13 +22,29 @@ struct au_hfile {
 	struct au_branch	*hf_br;
 };
 
+struct au_vdir;
+struct au_fidir {
+	aufs_bindex_t		fd_bbot;
+	aufs_bindex_t		fd_nent;
+	struct au_vdir		*fd_vdir_cache;
+	struct au_hfile		fd_hfile[];
+};
+
+static inline int au_fidir_sz(int nent)
+{
+	AuDebugOn(nent < 0);
+	return sizeof(struct au_fidir) + sizeof(struct au_hfile) * nent;
+}
+
 struct au_finfo {
 	atomic_t		fi_generation;
 
 	struct au_rwsem		fi_rwsem;
 	aufs_bindex_t		fi_btop;
 
-	struct au_hfile		fi_htop;
+	/* do not union them */
+	struct au_hfile		fi_htop;	/* for non-dir */
+	struct au_fidir		*fi_hdir;	/* for dir only */
 	struct rcu_head		rcu;
 } ____cacheline_aligned_in_smp;
 
@@ -46,10 +62,12 @@ void au_set_h_fptr(struct file *file, aufs_bindex_t bindex,
 		   struct file *h_file);
 
 void au_update_figen(struct file *file);
+struct au_fidir *au_fidir_alloc(struct super_block *sb);
+int au_fidir_realloc(struct au_finfo *finfo, int nbr, int may_shrink);
 
 void au_fi_init_once(void *_fi);
 void au_finfo_fin(struct file *file);
-int au_finfo_init(struct file *file);
+int au_finfo_init(struct file *file, struct au_fidir *fidir);
 
 /* ---------------------------------------------------------------------- */
 
@@ -88,18 +106,55 @@ static inline aufs_bindex_t au_fbtop(struct file *file)
 	return au_fi(file)->fi_btop;
 }
 
+static inline aufs_bindex_t au_fbbot_dir(struct file *file)
+{
+	FiMustAnyLock(file);
+	AuDebugOn(!au_fi(file)->fi_hdir);
+	return au_fi(file)->fi_hdir->fd_bbot;
+}
+
+static inline struct au_vdir *au_fvdir_cache(struct file *file)
+{
+	FiMustAnyLock(file);
+	AuDebugOn(!au_fi(file)->fi_hdir);
+	return au_fi(file)->fi_hdir->fd_vdir_cache;
+}
+
 static inline void au_set_fbtop(struct file *file, aufs_bindex_t bindex)
 {
 	FiMustWriteLock(file);
 	au_fi(file)->fi_btop = bindex;
 }
 
+static inline void au_set_fbbot_dir(struct file *file, aufs_bindex_t bindex)
+{
+	FiMustWriteLock(file);
+	AuDebugOn(!au_fi(file)->fi_hdir);
+	au_fi(file)->fi_hdir->fd_bbot = bindex;
+}
+
+static inline void au_set_fvdir_cache(struct file *file,
+				      struct au_vdir *vdir_cache)
+{
+	FiMustWriteLock(file);
+	AuDebugOn(!au_fi(file)->fi_hdir);
+	au_fi(file)->fi_hdir->fd_vdir_cache = vdir_cache;
+}
+
 static inline struct file *au_hf_top(struct file *file)
 {
 	FiMustAnyLock(file);
+	AuDebugOn(au_fi(file)->fi_hdir);
 	return au_fi(file)->fi_htop.hf_file;
 }
 
+static inline struct file *au_hf_dir(struct file *file, aufs_bindex_t bindex)
+{
+	FiMustAnyLock(file);
+	AuDebugOn(!au_fi(file)->fi_hdir);
+	return au_fi(file)->fi_hdir->fd_hfile[0 + bindex].hf_file;
+}
+
 /* todo: memory barrier? */
 static inline unsigned int au_figen(struct file *f)
 {

fs/aufs/finfo.c

@@ -23,9 +23,14 @@ void au_set_h_fptr(struct file *file, aufs_bindex_t bindex, struct file *val)
 {
 	struct au_finfo *finfo = au_fi(file);
 	struct au_hfile *hf;
+	struct au_fidir *fidir;
 
-	AuDebugOn(finfo->fi_btop != bindex);
-	hf = &finfo->fi_htop;
+	fidir = finfo->fi_hdir;
+	if (!fidir) {
+		AuDebugOn(finfo->fi_btop != bindex);
+		hf = &finfo->fi_htop;
+	} else
+		hf = fidir->fd_hfile + bindex;
 
 	if (hf && hf->hf_file)
 		au_hfput(hf, vfsub_file_execed(file));
@@ -45,11 +50,52 @@ void au_update_figen(struct file *file)
 
 /* ---------------------------------------------------------------------- */
 
+struct au_fidir *au_fidir_alloc(struct super_block *sb)
+{
+	struct au_fidir *fidir;
+	int nbr;
+
+	nbr = au_sbbot(sb) + 1;
+	if (nbr < 2)
+		nbr = 2; /* initial allocate for 2 branches */
+	fidir = kzalloc(au_fidir_sz(nbr), GFP_NOFS);
+	if (fidir) {
+		fidir->fd_bbot = -1;
+		fidir->fd_nent = nbr;
+	}
+
+	return fidir;
+}
+
+int au_fidir_realloc(struct au_finfo *finfo, int nbr, int may_shrink)
+{
+	int err;
+	struct au_fidir *fidir, *p;
+
+	AuRwMustWriteLock(&finfo->fi_rwsem);
+	fidir = finfo->fi_hdir;
+	AuDebugOn(!fidir);
+
+	err = -ENOMEM;
+	p = au_kzrealloc(fidir, au_fidir_sz(fidir->fd_nent), au_fidir_sz(nbr),
+			 GFP_NOFS, may_shrink);
+	if (p) {
+		p->fd_nent = nbr;
+		finfo->fi_hdir = p;
+		err = 0;
+	}
+
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
 void au_finfo_fin(struct file *file)
 {
 	struct au_finfo *finfo;
 
 	finfo = au_fi(file);
+	AuDebugOn(finfo->fi_hdir);
 	AuRwDestroy(&finfo->fi_rwsem);
 	au_cache_free_finfo(finfo);
 }
@@ -61,7 +107,7 @@ void au_fi_init_once(void *_finfo)
 	au_rw_init(&finfo->fi_rwsem);
 }
 
-int au_finfo_init(struct file *file)
+int au_finfo_init(struct file *file, struct au_fidir *fidir)
 {
 	int err;
 	struct au_finfo *finfo;
@@ -76,6 +122,7 @@ int au_finfo_init(struct file *file)
 	err = 0;
 	au_rw_write_lock(&finfo->fi_rwsem);
 	finfo->fi_btop = -1;
+	finfo->fi_hdir = fidir;
 	atomic_set(&finfo->fi_generation, au_digen(dentry));
 	/* smp_mb(); */ /* atomic_set */