[JFFS2] Add symlink caching support.

Signed-off-by: Artem B. Bityuckiy <dedekind@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

fs/jffs2/dir.c

@@ -7,7 +7,7 @@
  *
  * For licensing information, see the file 'LICENCE' in this directory.
  *
- * $Id: dir.c,v 1.84 2004/11/16 20:36:11 dwmw2 Exp $
+ * $Id: dir.c,v 1.85 2005/03/01 10:34:03 dedekind Exp $
  *
  */
 
@@ -296,11 +296,11 @@ static int jffs2_symlink (struct inode *dir_i, struct dentry *dentry, const char
 	struct jffs2_full_dirent *fd;
 	int namelen;
 	uint32_t alloclen, phys_ofs;
-	int ret;
+	int ret, targetlen = strlen(target);
 
 	/* FIXME: If you care. We'd need to use frags for the target
 	   if it grows much more than this */
-	if (strlen(target) > 254)
+	if (targetlen > 254)
 		return -EINVAL;
 
 	ri = jffs2_alloc_raw_inode();
@@ -314,7 +314,7 @@ static int jffs2_symlink (struct inode *dir_i, struct dentry *dentry, const char
 	 * Just the node will do for now, though 
 	 */
 	namelen = dentry->d_name.len;
-	ret = jffs2_reserve_space(c, sizeof(*ri) + strlen(target), &phys_ofs, &alloclen, ALLOC_NORMAL);
+	ret = jffs2_reserve_space(c, sizeof(*ri) + targetlen, &phys_ofs, &alloclen, ALLOC_NORMAL);
 
 	if (ret) {
 		jffs2_free_raw_inode(ri);
@@ -333,16 +333,16 @@ static int jffs2_symlink (struct inode *dir_i, struct dentry *dentry, const char
 
 	f = JFFS2_INODE_INFO(inode);
 
-	inode->i_size = strlen(target);
+	inode->i_size = targetlen;
 	ri->isize = ri->dsize = ri->csize = cpu_to_je32(inode->i_size);
 	ri->totlen = cpu_to_je32(sizeof(*ri) + inode->i_size);
 	ri->hdr_crc = cpu_to_je32(crc32(0, ri, sizeof(struct jffs2_unknown_node)-4));
 
 	ri->compr = JFFS2_COMPR_NONE;
-	ri->data_crc = cpu_to_je32(crc32(0, target, strlen(target)));
+	ri->data_crc = cpu_to_je32(crc32(0, target, targetlen));
 	ri->node_crc = cpu_to_je32(crc32(0, ri, sizeof(*ri)-8));
 	
-	fn = jffs2_write_dnode(c, f, ri, target, strlen(target), phys_ofs, ALLOC_NORMAL);
+	fn = jffs2_write_dnode(c, f, ri, target, targetlen, phys_ofs, ALLOC_NORMAL);
 
 	jffs2_free_raw_inode(ri);
 
@@ -353,6 +353,20 @@ static int jffs2_symlink (struct inode *dir_i, struct dentry *dentry, const char
 		jffs2_clear_inode(inode);
 		return PTR_ERR(fn);
 	}
+
+	/* We use f->dents field to store the target path. */
+	f->dents = kmalloc(targetlen + 1, GFP_KERNEL);
+	if (!f->dents) {
+		printk(KERN_WARNING "Can't allocate %d bytes of memory\n", targetlen + 1);
+		up(&f->sem);
+		jffs2_complete_reservation(c);
+		jffs2_clear_inode(inode);
+		return -ENOMEM;
+	}
+
+	memcpy(f->dents, target, targetlen + 1);
+	D1(printk(KERN_DEBUG "jffs2_symlink: symlink's target '%s' cached\n", (char *)f->dents));
+
 	/* No data here. Only a metadata node, which will be 
 	   obsoleted by the first data write
 	*/

fs/jffs2/read.c

@@ -7,7 +7,7 @@
  *
  * For licensing information, see the file 'LICENCE' in this directory.
  *
- * $Id: read.c,v 1.38 2004/11/16 20:36:12 dwmw2 Exp $
+ * $Id: read.c,v 1.39 2005/03/01 10:34:03 dedekind Exp $
  *
  */
 
@@ -214,33 +214,3 @@ int jffs2_read_inode_range(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
 	return 0;
 }
 
-/* Core function to read symlink target. */
-char *jffs2_getlink(struct jffs2_sb_info *c, struct jffs2_inode_info *f)
-{
-	char *buf;
-	int ret;
-
-	down(&f->sem);
-
-	if (!f->metadata) {
-		printk(KERN_NOTICE "No metadata for symlink inode #%u\n", f->inocache->ino);
-		up(&f->sem);
-		return ERR_PTR(-EINVAL);
-	}
-	buf = kmalloc(f->metadata->size+1, GFP_USER);
-	if (!buf) {
-		up(&f->sem);
-		return ERR_PTR(-ENOMEM);
-	}
-	buf[f->metadata->size]=0;
-
-	ret = jffs2_read_dnode(c, f, f->metadata, buf, 0, f->metadata->size);
-
-	up(&f->sem);
-
-	if (ret) {
-		kfree(buf);
-		return ERR_PTR(ret);
-	}
-	return buf;
-}

fs/jffs2/readinode.c

@@ -7,7 +7,7 @@
  *
  * For licensing information, see the file 'LICENCE' in this directory.
  *
- * $Id: readinode.c,v 1.118 2005/02/27 23:01:33 dwmw2 Exp $
+ * $Id: readinode.c,v 1.119 2005/03/01 10:34:03 dedekind Exp $
  *
  */
 
@@ -623,6 +623,40 @@ static int jffs2_do_read_inode_internal(struct jffs2_sb_info *c,
 		   case. */
 		if (!je32_to_cpu(latest_node->isize))
 			latest_node->isize = latest_node->dsize;
+
+		if (f->inocache->state != INO_STATE_CHECKING) {
+			/* Symlink's inode data is the target path. Read it and
+			 * keep in RAM to facilitate quick follow symlink operation.
+			 * We use f->dents field to store the target path, which
+			 * is somewhat ugly. */
+			f->dents = kmalloc(je32_to_cpu(latest_node->csize) + 1, GFP_KERNEL);
+			if (!f->dents) {
+				printk(KERN_WARNING "Can't allocate %d bytes of memory "
+						"for the symlink target path cache\n",
+						je32_to_cpu(latest_node->csize));
+				up(&f->sem);
+				jffs2_do_clear_inode(c, f);
+				return -ENOMEM;
+			}
+			
+			ret = jffs2_flash_read(c, ref_offset(fn->raw) + sizeof(*latest_node),
+						je32_to_cpu(latest_node->csize), &retlen, (char *)f->dents);
+			
+			if (ret  || retlen != je32_to_cpu(latest_node->csize)) {
+				if (retlen != je32_to_cpu(latest_node->csize))
+					ret = -EIO;
+				kfree(f->dents);
+				f->dents = NULL;
+				up(&f->sem);
+				jffs2_do_clear_inode(c, f);
+				return -ret;
+			}
+
+			((char *)f->dents)[je32_to_cpu(latest_node->csize)] = '\0';
+			D1(printk(KERN_DEBUG "jffs2_do_read_inode(): symlink's target '%s' cached\n",
+						(char *)f->dents));
+		}
+		
 		/* fall through... */
 
 	case S_IFBLK:
@@ -683,12 +717,20 @@ void jffs2_do_clear_inode(struct jffs2_sb_info *c, struct jffs2_inode_info *f)
 
 	jffs2_kill_fragtree(&f->fragtree, deleted?c:NULL);
 
-	fds = f->dents;
+	/* For symlink inodes we us f->dents to store the target path name */
+	if (S_ISLNK(OFNI_EDONI_2SFFJ(f)->i_mode)) {
+		if (f->dents) {
+			kfree(f->dents);
+			f->dents = NULL;
+		}
+	} else {
+		fds = f->dents;
 
-	while(fds) {
-		fd = fds;
-		fds = fd->next;
-		jffs2_free_full_dirent(fd);
+		while(fds) {
+			fd = fds;
+			fds = fd->next;
+			jffs2_free_full_dirent(fd);
+		}
 	}
 
 	if (f->inocache && f->inocache->state != INO_STATE_CHECKING) {

fs/jffs2/symlink.c

@@ -7,7 +7,7 @@
  *
  * For licensing information, see the file 'LICENCE' in this directory.
  *
- * $Id: symlink.c,v 1.14 2004/11/16 20:36:12 dwmw2 Exp $
+ * $Id: symlink.c,v 1.16 2005/03/01 10:50:48 dedekind Exp $
  *
  */
 
@@ -19,27 +19,45 @@
 #include "nodelist.h"
 
 static int jffs2_follow_link(struct dentry *dentry, struct nameidata *nd);
-static void jffs2_put_link(struct dentry *dentry, struct nameidata *nd);
 
 struct inode_operations jffs2_symlink_inode_operations =
 {	
 	.readlink =	generic_readlink,
 	.follow_link =	jffs2_follow_link,
-	.put_link =	jffs2_put_link,
 	.setattr =	jffs2_setattr
 };
 
 static int jffs2_follow_link(struct dentry *dentry, struct nameidata *nd)
 {
-	unsigned char *buf;
-	buf = jffs2_getlink(JFFS2_SB_INFO(dentry->d_inode->i_sb), JFFS2_INODE_INFO(dentry->d_inode));
-	nd_set_link(nd, buf);
+	struct jffs2_inode_info *f = JFFS2_INODE_INFO(dentry->d_inode);
+	
+	/*
+	 * We don't acquire the f->sem mutex here since the only data we
+	 * use is f->dents which in case of the symlink inode points to the
+	 * symlink's target path.
+	 *
+	 * 1. If we are here the inode has already built and f->dents has
+	 * to point to the target path.
+	 * 2. Nobody uses f->dents (if the inode is symlink's inode). The
+	 * exception is inode freeing function which frees f->dents. But
+	 * it can't be called while we are here and before VFS has
+	 * stopped using our f->dents string which we provide by means of
+	 * nd_set_link() call.
+	 */
+	
+	if (!f->dents) {
+		printk(KERN_ERR "jffs2_follow_link(): can't find symlink taerget\n");
+		return -EIO;
+	}
+	D1(printk(KERN_DEBUG "jffs2_follow_link(): target path is '%s'\n", (char *) f->dents));
+
+	nd_set_link(nd, (char *)f->dents);
+	
+	/*
+	 * We unlock the f->sem mutex but VFS will use the f->dents string. This is safe
+	 * since the only way that may cause f->dents to be changed is iput() operation.
+	 * But VFS will not use f->dents after iput() has been called.
+	 */
 	return 0;
 }
 
-static void jffs2_put_link(struct dentry *dentry, struct nameidata *nd)
-{
-	char *s = nd_get_link(nd);
-	if (!IS_ERR(s))
-		kfree(s);
-}

fs/jffs2/write.c

@@ -7,7 +7,7 @@
  *
  * For licensing information, see the file 'LICENCE' in this directory.
  *
- * $Id: write.c,v 1.90 2005/01/28 18:53:01 hammache Exp $
+ * $Id: write.c,v 1.91 2005/03/01 10:34:03 dedekind Exp $
  *
  */
 
@@ -644,20 +644,23 @@ int jffs2_do_unlink(struct jffs2_sb_info *c, struct jffs2_inode_info *dir_f,
 
 		down(&dead_f->sem);
 
-		while (dead_f->dents) {
-			/* There can be only deleted ones */
-			fd = dead_f->dents;
-			
-			dead_f->dents = fd->next;
-			
-			if (fd->ino) {
-				printk(KERN_WARNING "Deleting inode #%u with active dentry \"%s\"->ino #%u\n",
-				       dead_f->inocache->ino, fd->name, fd->ino);
-			} else {
-				D1(printk(KERN_DEBUG "Removing deletion dirent for \"%s\" from dir ino #%u\n", fd->name, dead_f->inocache->ino));
+		if (S_ISDIR(OFNI_EDONI_2SFFJ(dead_f)->i_mode)) {
+			while (dead_f->dents) {
+				/* There can be only deleted ones */
+				fd = dead_f->dents;
+				
+				dead_f->dents = fd->next;
+				
+				if (fd->ino) {
+					printk(KERN_WARNING "Deleting inode #%u with active dentry \"%s\"->ino #%u\n",
+					       dead_f->inocache->ino, fd->name, fd->ino);
+				} else {
+					D1(printk(KERN_DEBUG "Removing deletion dirent for \"%s\" from dir ino #%u\n",
+						fd->name, dead_f->inocache->ino));
+				}
+				jffs2_mark_node_obsolete(c, fd->raw);
+				jffs2_free_full_dirent(fd);
 			}
-			jffs2_mark_node_obsolete(c, fd->raw);
-			jffs2_free_full_dirent(fd);
 		}
 
 		dead_f->inocache->nlink--;