[JFFS2] Track parent inode for directories (for NFS export)

To support NFS export, we need to know the parent inode of directories.
Rather than growing the jffs2_inode_cache structure, share space with
the nlink field -- which was always set to 1 for directories anyway.
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

fs/jffs2/build.c

@@ -46,7 +46,7 @@ next_inode(int *i, struct jffs2_inode_cache *ic, struct jffs2_sb_info *c)
 
 
 static void jffs2_build_inode_pass1(struct jffs2_sb_info *c,
-					struct jffs2_inode_cache *ic)
+				    struct jffs2_inode_cache *ic)
 {
 	struct jffs2_full_dirent *fd;
 
@@ -68,11 +68,17 @@ static void jffs2_build_inode_pass1(struct jffs2_sb_info *c,
 			continue;
 		}
 
-		if (child_ic->nlink++ && fd->type == DT_DIR) {
-			JFFS2_ERROR("child dir \"%s\" (ino #%u) of dir ino #%u appears to be a hard link\n",
-				fd->name, fd->ino, ic->ino);
-			/* TODO: What do we do about it? */
-		}
+		if (fd->type == DT_DIR) {
+			if (child_ic->pino_nlink) {
+				JFFS2_ERROR("child dir \"%s\" (ino #%u) of dir ino #%u appears to be a hard link\n",
+					    fd->name, fd->ino, ic->ino);
+				/* TODO: What do we do about it? */
+			} else {
+				child_ic->pino_nlink = ic->ino;
+			}
+		} else
+			child_ic->pino_nlink++;
+
 		dbg_fsbuild("increased nlink for child \"%s\" (ino #%u)\n", fd->name, fd->ino);
 		/* Can't free scan_dents so far. We might need them in pass 2 */
 	}
@@ -125,7 +131,7 @@ static int jffs2_build_filesystem(struct jffs2_sb_info *c)
 	dbg_fsbuild("pass 2 starting\n");
 
 	for_each_inode(i, c, ic) {
-		if (ic->nlink)
+		if (ic->pino_nlink)
 			continue;
 
 		jffs2_build_remove_unlinked_inode(c, ic, &dead_fds);
@@ -232,16 +238,19 @@ static void jffs2_build_remove_unlinked_inode(struct jffs2_sb_info *c,
 			/* Reduce nlink of the child. If it's now zero, stick it on the
 			   dead_fds list to be cleaned up later. Else just free the fd */
 
-			child_ic->nlink--;
+			if (fd->type == DT_DIR)
+				child_ic->pino_nlink = 0;
+			else
+				child_ic->pino_nlink--;
 
-			if (!child_ic->nlink) {
-				dbg_fsbuild("inode #%u (\"%s\") has now got zero nlink, adding to dead_fds list.\n",
+			if (!child_ic->pino_nlink) {
+				dbg_fsbuild("inode #%u (\"%s\") now has no links; adding to dead_fds list.\n",
 					  fd->ino, fd->name);
 				fd->next = *dead_fds;
 				*dead_fds = fd;
 			} else {
 				dbg_fsbuild("inode #%u (\"%s\") has now got nlink %d. Ignoring.\n",
-					  fd->ino, fd->name, child_ic->nlink);
+					  fd->ino, fd->name, child_ic->pino_nlink);
 				jffs2_free_full_dirent(fd);
 			}
 		}

fs/jffs2/dir.c

@@ -226,7 +226,8 @@ static int jffs2_create(struct inode *dir_i, struct dentry *dentry, int mode,
 	d_instantiate(dentry, inode);
 
 	D1(printk(KERN_DEBUG "jffs2_create: Created ino #%lu with mode %o, nlink %d(%d). nrpages %ld\n",
-		  inode->i_ino, inode->i_mode, inode->i_nlink, f->inocache->nlink, inode->i_mapping->nrpages));
+		  inode->i_ino, inode->i_mode, inode->i_nlink,
+		  f->inocache->pino_nlink, inode->i_mapping->nrpages));
 	return 0;
 
  fail:
@@ -250,7 +251,7 @@ static int jffs2_unlink(struct inode *dir_i, struct dentry *dentry)
 	ret = jffs2_do_unlink(c, dir_f, dentry->d_name.name,
 			      dentry->d_name.len, dead_f, now);
 	if (dead_f->inocache)
-		dentry->d_inode->i_nlink = dead_f->inocache->nlink;
+		dentry->d_inode->i_nlink = dead_f->inocache->pino_nlink;
 	if (!ret)
 		dir_i->i_mtime = dir_i->i_ctime = ITIME(now);
 	return ret;
@@ -283,7 +284,7 @@ static int jffs2_link (struct dentry *old_dentry, struct inode *dir_i, struct de
 
 	if (!ret) {
 		mutex_lock(&f->sem);
-		old_dentry->d_inode->i_nlink = ++f->inocache->nlink;
+		old_dentry->d_inode->i_nlink = ++f->inocache->pino_nlink;
 		mutex_unlock(&f->sem);
 		d_instantiate(dentry, old_dentry->d_inode);
 		dir_i->i_mtime = dir_i->i_ctime = ITIME(now);
@@ -500,11 +501,14 @@ static int jffs2_mkdir (struct inode *dir_i, struct dentry *dentry, int mode)
 
 	inode->i_op = &jffs2_dir_inode_operations;
 	inode->i_fop = &jffs2_dir_operations;
-	/* Directories get nlink 2 at start */
-	inode->i_nlink = 2;
 
 	f = JFFS2_INODE_INFO(inode);
 
+	/* Directories get nlink 2 at start */
+	inode->i_nlink = 2;
+	/* but ic->pino_nlink is the parent ino# */
+	f->inocache->pino_nlink = dir_i->i_ino;
+
 	ri->data_crc = cpu_to_je32(0);
 	ri->node_crc = cpu_to_je32(crc32(0, ri, sizeof(*ri)-8));
 
@@ -601,17 +605,25 @@ static int jffs2_mkdir (struct inode *dir_i, struct dentry *dentry, int mode)
 
 static int jffs2_rmdir (struct inode *dir_i, struct dentry *dentry)
 {
+	struct jffs2_sb_info *c = JFFS2_SB_INFO(dir_i->i_sb);
+	struct jffs2_inode_info *dir_f = JFFS2_INODE_INFO(dir_i);
 	struct jffs2_inode_info *f = JFFS2_INODE_INFO(dentry->d_inode);
 	struct jffs2_full_dirent *fd;
 	int ret;
+	uint32_t now = get_seconds();
 
 	for (fd = f->dents ; fd; fd = fd->next) {
 		if (fd->ino)
 			return -ENOTEMPTY;
 	}
-	ret = jffs2_unlink(dir_i, dentry);
-	if (!ret)
+
+	ret = jffs2_do_unlink(c, dir_f, dentry->d_name.name,
+			      dentry->d_name.len, f, now);
+	if (!ret) {
+		dir_i->i_mtime = dir_i->i_ctime = ITIME(now);
+		clear_nlink(dentry->d_inode);
 		drop_nlink(dir_i);
+	}
 	return ret;
 }
 
@@ -824,7 +836,10 @@ static int jffs2_rename (struct inode *old_dir_i, struct dentry *old_dentry,
 		   inode which didn't exist. */
 		if (victim_f->inocache) {
 			mutex_lock(&victim_f->sem);
-			victim_f->inocache->nlink--;
+			if (S_ISDIR(new_dentry->d_inode->i_mode))
+				victim_f->inocache->pino_nlink = 0;
+			else
+				victim_f->inocache->pino_nlink--;
 			mutex_unlock(&victim_f->sem);
 		}
 	}
@@ -845,8 +860,8 @@ static int jffs2_rename (struct inode *old_dir_i, struct dentry *old_dentry,
 		struct jffs2_inode_info *f = JFFS2_INODE_INFO(old_dentry->d_inode);
 		mutex_lock(&f->sem);
 		inc_nlink(old_dentry->d_inode);
-		if (f->inocache)
-			f->inocache->nlink++;
+		if (f->inocache && !S_ISDIR(old_dentry->d_inode->i_mode))
+			f->inocache->pino_nlink++;
 		mutex_unlock(&f->sem);
 
 		printk(KERN_NOTICE "jffs2_rename(): Link succeeded, unlink failed (err %d). You now have a hard link\n", ret);

fs/jffs2/erase.c

@@ -294,7 +294,7 @@ static inline void jffs2_remove_node_refs_from_ino_list(struct jffs2_sb_info *c,
 			break;
 #endif
 		default:
-			if (ic->nodes == (void *)ic && ic->nlink == 0)
+			if (ic->nodes == (void *)ic && ic->pino_nlink == 0)
 				jffs2_del_ino_cache(c, ic);
 	}
 }

fs/jffs2/fs.c

@@ -273,7 +273,7 @@ struct inode *jffs2_iget(struct super_block *sb, unsigned long ino)
 	inode->i_mtime = ITIME(je32_to_cpu(latest_node.mtime));
 	inode->i_ctime = ITIME(je32_to_cpu(latest_node.ctime));
 
-	inode->i_nlink = f->inocache->nlink;
+	inode->i_nlink = f->inocache->pino_nlink;
 
 	inode->i_blocks = (inode->i_size + 511) >> 9;
 
@@ -286,13 +286,12 @@ struct inode *jffs2_iget(struct super_block *sb, unsigned long ino)
 	case S_IFDIR:
 	{
 		struct jffs2_full_dirent *fd;
+		inode->i_nlink = 2; /* parent and '.' */
 
 		for (fd=f->dents; fd; fd = fd->next) {
 			if (fd->type == DT_DIR && fd->ino)
 				inc_nlink(inode);
 		}
-		/* and '..' */
-		inc_nlink(inode);
 		/* Root dir gets i_nlink 3 for some reason */
 		if (inode->i_ino == 1)
 			inc_nlink(inode);

fs/jffs2/gc.c

@@ -161,8 +161,8 @@ int jffs2_garbage_collect_pass(struct jffs2_sb_info *c)
 			continue;
 		}
 
-		if (!ic->nlink) {
-			D1(printk(KERN_DEBUG "Skipping check of ino #%d with nlink zero\n",
+		if (!ic->pino_nlink) {
+			D1(printk(KERN_DEBUG "Skipping check of ino #%d with nlink/pino zero\n",
 				  ic->ino));
 			spin_unlock(&c->inocache_lock);
 			jffs2_xattr_delete_inode(c, ic);
@@ -398,7 +398,7 @@ int jffs2_garbage_collect_pass(struct jffs2_sb_info *c)
 	   it's vaguely possible. */
 
 	inum = ic->ino;
-	nlink = ic->nlink;
+	nlink = ic->pino_nlink;
 	spin_unlock(&c->inocache_lock);
 
 	f = jffs2_gc_fetch_inode(c, inum, !nlink);

fs/jffs2/nodelist.h

@@ -177,7 +177,10 @@ struct jffs2_inode_cache {
 #ifdef CONFIG_JFFS2_FS_XATTR
 	struct jffs2_xattr_ref *xref;
 #endif
-	int nlink;
+	uint32_t pino_nlink;	/* Directories store parent inode
+				   here; other inodes store nlink.
+				   Zero always means that it's
+				   completely unlinked. */
 };
 
 /* Inode states for 'state' above. We need the 'GC' state to prevent

fs/jffs2/nodemgmt.c

@@ -709,7 +709,7 @@ void jffs2_mark_node_obsolete(struct jffs2_sb_info *c, struct jffs2_raw_node_ref
 				break;
 #endif
 			default:
-				if (ic->nodes == (void *)ic && ic->nlink == 0)
+				if (ic->nodes == (void *)ic && ic->pino_nlink == 0)
 					jffs2_del_ino_cache(c, ic);
 				break;
 		}

fs/jffs2/readinode.c

@@ -1123,7 +1123,8 @@ static int jffs2_do_read_inode_internal(struct jffs2_sb_info *c,
 	size_t retlen;
 	int ret;
 
-	dbg_readinode("ino #%u nlink is %d\n", f->inocache->ino, f->inocache->nlink);
+	dbg_readinode("ino #%u pino/nlink is %d\n", f->inocache->ino,
+		      f->inocache->pino_nlink);
 
 	memset(&rii, 0, sizeof(rii));
 
@@ -1358,7 +1359,7 @@ int jffs2_do_read_inode(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
 		}
 		dbg_readinode("creating inocache for root inode\n");
 		memset(f->inocache, 0, sizeof(struct jffs2_inode_cache));
-		f->inocache->ino = f->inocache->nlink = 1;
+		f->inocache->ino = f->inocache->pino_nlink = 1;
 		f->inocache->nodes = (struct jffs2_raw_node_ref *)f->inocache;
 		f->inocache->state = INO_STATE_READING;
 		jffs2_add_ino_cache(c, f->inocache);
@@ -1401,7 +1402,7 @@ void jffs2_do_clear_inode(struct jffs2_sb_info *c, struct jffs2_inode_info *f)
 	jffs2_clear_acl(f);
 	jffs2_xattr_delete_inode(c, f->inocache);
 	mutex_lock(&f->sem);
-	deleted = f->inocache && !f->inocache->nlink;
+	deleted = f->inocache && !f->inocache->pino_nlink;
 
 	if (f->inocache && f->inocache->state != INO_STATE_CHECKING)
 		jffs2_set_inocache_state(c, f->inocache, INO_STATE_CLEARING);

fs/jffs2/scan.c

@@ -940,7 +940,7 @@ struct jffs2_inode_cache *jffs2_scan_make_ino_cache(struct jffs2_sb_info *c, uin
 	ic->nodes = (void *)ic;
 	jffs2_add_ino_cache(c, ic);
 	if (ino == 1)
-		ic->nlink = 1;
+		ic->pino_nlink = 1;
 	return ic;
 }
 

fs/jffs2/wbuf.c

@@ -494,7 +494,7 @@ static void jffs2_wbuf_recover(struct jffs2_sb_info *c)
 				/* If it's an in-core inode, then we have to adjust any
 				   full_dirent or full_dnode structure to point to the
 				   new version instead of the old */
-				f = jffs2_gc_fetch_inode(c, ic->ino, !ic->nlink);
+				f = jffs2_gc_fetch_inode(c, ic->ino, !ic->pino_nlink);
 				if (IS_ERR(f)) {
 					/* Should never happen; it _must_ be present */
 					JFFS2_ERROR("Failed to iget() ino #%u, err %ld\n",

fs/jffs2/write.c

@@ -19,7 +19,8 @@
 #include "compr.h"
 
 
-int jffs2_do_new_inode(struct jffs2_sb_info *c, struct jffs2_inode_info *f, uint32_t mode, struct jffs2_raw_inode *ri)
+int jffs2_do_new_inode(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
+		       uint32_t mode, struct jffs2_raw_inode *ri)
 {
 	struct jffs2_inode_cache *ic;
 
@@ -31,7 +32,7 @@ int jffs2_do_new_inode(struct jffs2_sb_info *c, struct jffs2_inode_info *f, uint
 	memset(ic, 0, sizeof(*ic));
 
 	f->inocache = ic;
-	f->inocache->nlink = 1;
+	f->inocache->pino_nlink = 1; /* Will be overwritten shortly for directories */
 	f->inocache->nodes = (struct jffs2_raw_node_ref *)f->inocache;
 	f->inocache->state = INO_STATE_PRESENT;
 
@@ -635,9 +636,9 @@ int jffs2_do_unlink(struct jffs2_sb_info *c, struct jffs2_inode_info *dir_f,
 					jffs2_mark_node_obsolete(c, fd->raw);
 				jffs2_free_full_dirent(fd);
 			}
-		}
-
-		dead_f->inocache->nlink--;
+			dead_f->inocache->pino_nlink = 0;
+		} else
+			dead_f->inocache->pino_nlink--;
 		/* NB: Caller must set inode nlink if appropriate */
 		mutex_unlock(&dead_f->sem);
 	}

fs/jffs2/xattr.c

@@ -592,7 +592,7 @@ void jffs2_xattr_delete_inode(struct jffs2_sb_info *c, struct jffs2_inode_cache
 	   When an inode with XATTR is removed, those XATTRs must be removed. */
 	struct jffs2_xattr_ref *ref, *_ref;
 
-	if (!ic || ic->nlink > 0)
+	if (!ic || ic->pino_nlink > 0)
 		return;
 
 	down_write(&c->xattr_sem);
@@ -829,7 +829,7 @@ void jffs2_build_xattr_subsystem(struct jffs2_sb_info *c)
 			   ref->xd and ref->ic are not valid yet. */
 			xd = jffs2_find_xattr_datum(c, ref->xid);
 			ic = jffs2_get_ino_cache(c, ref->ino);
-			if (!xd || !ic || !ic->nlink) {
+			if (!xd || !ic || !ic->pino_nlink) {
 				dbg_xattr("xref(ino=%u, xid=%u, xseqno=%u) is orphan.\n",
 					  ref->ino, ref->xid, ref->xseqno);
 				ref->xseqno |= XREF_DELETE_MARKER;