file-ids: Enlighten ID generation and storage

The unique id is 32 bit and consists only of the subid value. This
is _really_ enough. The genid part is just a hint for the tree-search
algirythm to avoid unneeded sys_kcmp calls.

Plus, generate IDs for special files. This will make it easier to
move the regfiles into into separate files (see the respective patch
for details).
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

cr-dump.c

@@ -93,7 +93,7 @@ struct fd_parms {
 	unsigned int	flags;
 	unsigned int	type;
 
-	u64		id;
+	u32		id;
 	pid_t		pid;
 };
 
@@ -125,18 +125,11 @@ static int dump_one_reg_file(const struct fd_parms *p, int lfd,
 	e.flags = p->flags;
 	e.pos	= p->pos;
 	e.addr	= p->fd_name;
-	e.id	= FD_ID_INVALID;
+	e.id	= p->id;
 
-	if (likely(!fd_is_special(&e))) {
-		u64 id;
-
-		id = fd_id_entry_collect(p->id, p->pid, p->fd_name);
-		if (id < 0)
-			goto err;
-
-		/* Now it might have completely new ID here */
-		e.id = id;
-	}
+	ret = fd_id_generate(p->pid, &e);
+	if (ret < 0)
+		goto err;
 
 	pr_info("fdinfo: type: %2x len: %2x flags: %4x pos: %8lx addr: %16lx\n",
 		p->type, len, p->flags, p->pos, p->fd_name);

cr-show.c

@@ -84,7 +84,7 @@ static void show_files(int fd_files)
 			goto out;
 
 		pr_msg("type: %s flags: %4x pos: %8x "
-		       "addr: %16lx id: %16lx",
+		       "addr: %16lx id: %8lx",
 		       fdtype2s(e.type), e.flags, e.pos, e.addr, e.id);
 
 		if (e.len) {

file-ids.c

@@ -64,13 +64,8 @@ struct fd_id_entry {
 	struct rb_root	subtree_root;
 	struct rb_node	subtree_node;
 
-	union {
-		struct {
-			u32		genid;	/* generic id, may have duplicates */
-			u32		subid;	/* subid is always unique */
-		} key;
-		u64			id;
-	} u;
+	u32		genid;	/* generic id, may have duplicates */
+	u32		subid;	/* subid is always unique */
 
 	pid_t		pid;
 	int		fd;
@@ -80,7 +75,7 @@ static void show_subnode(struct rb_node *node, int self)
 {
 	struct fd_id_entry *this = rb_entry(node, struct fd_id_entry, subtree_node);
 
-	pr_info("\t\t| %x.%x %s\n", this->u.key.genid, this->u.key.subid,
+	pr_info("\t\t| %x.%x %s\n", this->genid, this->subid,
 			self ? "(self)" : "");
 	if (node->rb_left) {
 		pr_info("\t\t| left:\n");
@@ -104,7 +99,7 @@ static void show_node(struct rb_node *node)
 {
 	struct fd_id_entry *this = rb_entry(node, struct fd_id_entry, node);
 
-	pr_info("\t%x.%x\n", this->u.key.genid, this->u.key.subid);
+	pr_info("\t%x.%x\n", this->genid, this->subid);
 	if (node->rb_left) {
 		pr_info("\tleft:\n");
 		show_node(node->rb_left);
@@ -133,7 +128,7 @@ void fd_id_show_tree(void)
 
 static unsigned long fd_id_entries_subid = 1;
 
-static struct fd_id_entry *alloc_fd_id_entry(u32 genid, pid_t pid, int fd)
+static struct fd_id_entry *alloc_fd_id_entry(pid_t pid, struct fdinfo_entry *fe)
 {
 	struct fd_id_entry *e;
 
@@ -141,13 +136,13 @@ static struct fd_id_entry *alloc_fd_id_entry(u32 genid, pid_t pid, int fd)
 	if (!e)
 		goto err;
 
-	e->u.key.subid	= fd_id_entries_subid++;
-	e->u.key.genid	= genid;
+	e->subid	= fd_id_entries_subid++;
+	e->genid	= fe->id;
 	e->pid		= pid;
-	e->fd		= fd;
+	e->fd		= (int)fe->addr;
 
 	/* Make sure no overflow here */
-	BUG_ON(!e->u.key.subid);
+	BUG_ON(!e->subid);
 
 	rb_init_node(&e->node);
 	rb_init_node(&e->subtree_node);
@@ -158,8 +153,8 @@ err:
 	return e;
 }
 
-static struct fd_id_entry *
-lookup_alloc_subtree(struct fd_id_entry *e, u32 genid, pid_t pid, int fd)
+static struct fd_id_entry *fd_id_generate_sub(struct fd_id_entry *e,
+		pid_t pid, struct fdinfo_entry *fe)
 {
 	struct rb_node *node = e->subtree_root.rb_node;
 	struct fd_id_entry *sub = NULL;
@@ -171,7 +166,7 @@ lookup_alloc_subtree(struct fd_id_entry *e, u32 genid, pid_t pid, int fd)
 
 	while (node) {
 		struct fd_id_entry *this = rb_entry(node, struct fd_id_entry, subtree_node);
-		int ret = sys_kcmp(this->pid, pid, KCMP_FILE, this->fd, fd);
+		int ret = sys_kcmp(this->pid, pid, KCMP_FILE, this->fd, (int)fe->addr);
 
 		parent = *new;
 		if (ret < 0)
@@ -182,16 +177,15 @@ lookup_alloc_subtree(struct fd_id_entry *e, u32 genid, pid_t pid, int fd)
 			return this;
 	}
 
-	sub = alloc_fd_id_entry(genid, pid, fd);
+	sub = alloc_fd_id_entry(pid, fe);
 	if (!sub)
-		goto err;
+		return NULL;
 
 	rb_link_and_balance(&e->subtree_root, &sub->subtree_node, parent, new);
-err:
 	return sub;
 }
 
-static struct fd_id_entry *lookup_alloc_node(u32 genid, pid_t pid, int fd)
+static struct fd_id_entry *fd_id_generate_gen(pid_t pid, struct fdinfo_entry *fe)
 {
 	struct rb_node *node = fd_id_root.rb_node;
 	struct fd_id_entry *e = NULL;
@@ -203,31 +197,36 @@ static struct fd_id_entry *lookup_alloc_node(u32 genid, pid_t pid, int fd)
 		struct fd_id_entry *this = rb_entry(node, struct fd_id_entry, node);
 
 		parent = *new;
-		if (genid < this->u.key.genid)
+		if (fe->id < this->genid)
 			node = node->rb_left, new = &((*new)->rb_left);
-		else if (genid > this->u.key.genid)
+		else if (fe->id > this->genid)
 			node = node->rb_right, new = &((*new)->rb_right);
 		else
-			return lookup_alloc_subtree(this, genid, pid, fd);
+			return fd_id_generate_sub(this, pid, fe);
 	}
 
-	e = alloc_fd_id_entry(genid, pid, fd);
+	e = alloc_fd_id_entry(pid, fe);
 	if (!e)
-		goto err;
+		return NULL;
 
 	rb_link_and_balance(&fd_id_root, &e->node, parent, new);
-err:
 	return e;
 
 }
 
-long fd_id_entry_collect(u32 genid, pid_t pid, int fd)
+int fd_id_generate(pid_t pid, struct fdinfo_entry *fe)
 {
-	struct fd_id_entry *e = NULL;
+	struct fd_id_entry *fid;
+
+	if (fd_is_special(fe)) {
+		fe->id = fd_id_entries_subid++;
+		return 0;
+	}
 
-	e = lookup_alloc_node(genid, pid, fd);
-	if (e == NULL)
+	fid = fd_id_generate_gen(pid, fe);
+	if (!fid)
 		return -ENOMEM;
 
-	return e->u.id;
+	fe->id = fid->subid;
+	return 0;
 }

include/file-ids.h

@@ -5,13 +5,14 @@
 #include "types.h"
 #include "rbtree.h"
 
-#define FD_ID_INVALID		(-1UL)
-#define FD_PID_INVALID		((int)-2UL)
+#define FD_ID_INVALID		(-1U)
+#define FD_PID_INVALID		(-2U)
 
 #define MAKE_FD_GENID(dev, ino, pos) \
 	(((u32)(dev) ^ (u32)(ino) ^ (u32)(pos)))
 
-extern long fd_id_entry_collect(u32 genid, pid_t pid, int fd);
+struct fdinfo_entry;
+extern int fd_id_generate(pid_t pid, struct fdinfo_entry *fe);
 extern void fd_id_show_tree(void);
 
 #endif /* FILE_IDS_H__ */