[JFFS2] Add symlink caching support.

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

5 files changed, 117 insertions, 70 deletions

diff --git a/fs/jffs2/dir.c b/fs/jffs2/dir.c
index 757306fa3ff4..6421be874ce3 100644
--- a/fs/jffs2/dir.c
+++ b/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
         */
diff --git a/fs/jffs2/read.c b/fs/jffs2/read.c
index eb493dc06db7..c7f9068907cf 100644
--- a/fs/jffs2/read.c
+++ b/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;
-}
diff --git a/fs/jffs2/readinode.c b/fs/jffs2/readinode.c
index a1980a9da531..ef552477c813 100644
--- a/fs/jffs2/readinode.c
+++ b/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) {
diff --git a/fs/jffs2/symlink.c b/fs/jffs2/symlink.c
index 7b1820d13712..65ab6b001dca 100644
--- a/fs/jffs2/symlink.c
+++ b/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);
-}
diff --git a/fs/jffs2/write.c b/fs/jffs2/write.c
index d6b4d55e70e4..f3910dc1c2c8 100644
--- a/fs/jffs2/write.c
+++ b/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--;