[PATCH] JFFS2 symlink cache

Artem B. Bityuckiy dedekind at infradead.org
Thu Feb 17 09:25:01 EST 2005


Hello,

here is the JFFS2 patch which adds the symlink caching. In practice, the 
patch speeds up the processes startup.

--
Best Regards,
Artem B. Bityuckiy,
St.-Petersburg, Russia.
-------------- next part --------------
diff --exclude=CVS -auNr mtd-pristine/fs/jffs2/dir.c mtd-symlink/fs/jffs2/dir.c
--- mtd-pristine/fs/jffs2/dir.c	2005-02-16 10:35:07.000000000 +0300
+++ mtd-symlink/fs/jffs2/dir.c	2005-02-15 12:45:02.000000000 +0300
@@ -296,11 +296,11 @@
 	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 @@
 	 * 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 @@
 
 	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 @@
 		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
 	*/
diff --exclude=CVS -auNr mtd-pristine/fs/jffs2/read.c mtd-symlink/fs/jffs2/read.c
--- mtd-pristine/fs/jffs2/read.c	2005-02-16 10:35:08.000000000 +0300
+++ mtd-symlink/fs/jffs2/read.c	2005-02-15 13:23:05.000000000 +0300
@@ -218,7 +218,6 @@
 char *jffs2_getlink(struct jffs2_sb_info *c, struct jffs2_inode_info *f)
 {
 	char *buf;
-	int ret;
 
 	down(&f->sem);
 
@@ -232,15 +231,12 @@
 		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);
+	memcpy(buf, f->dents, f->metadata->size+1);
+
+	D1(printk(KERN_DEBUG "jffs2_getlink(): target path is '%s'\n", buf));
 
 	up(&f->sem);
 
-	if (ret) {
-		kfree(buf);
-		return ERR_PTR(ret);
-	}
 	return buf;
 }
diff --exclude=CVS -auNr mtd-pristine/fs/jffs2/readinode.c mtd-symlink/fs/jffs2/readinode.c
--- mtd-pristine/fs/jffs2/readinode.c	2005-02-16 10:35:07.000000000 +0300
+++ mtd-symlink/fs/jffs2/readinode.c	2005-02-17 17:18:01.629635056 +0300
@@ -4,7 +4,10 @@
  * Copyright (C) 2001-2003 Red Hat, Inc.
  *
  * Created by David Woodhouse <dwmw2 at infradead.org>
- *
+ * 
+ * 2005-02-16, Artem B. Bityuckiy, <dedekind at infradead.org>
+ * 	add symlink target caching support
+ * 	
  * For licensing information, see the file 'LICENCE' in this directory.
  *
  * $Id: readinode.c,v 1.117 2004/11/20 18:06:54 dwmw2 Exp $
@@ -623,6 +626,40 @@
 		   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:
@@ -680,12 +717,20 @@
 
 	jffs2_kill_fragtree(&f->fragtree, deleted?c:NULL);
 
-	fds = f->dents;
+	/* For symlink inodes we utilize f->dents to store the target path name */
+	if ((OFNI_EDONI_2SFFJ(f)->i_mode & S_IFMT) == S_IFLNK) {
+		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)


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