patch-2.2.18 linux/fs/nfs/symlink.c

• Lines: 160
• Date: Fri Sep 15 22:10:44 2000
• Orig file: v2.2.17/fs/nfs/symlink.c
• Orig date: Fri Apr 21 12:46:44 2000

diff -u --new-file --recursive --exclude-from /usr/src/exclude v2.2.17/fs/nfs/symlink.c linux/fs/nfs/symlink.c
@@ -5,13 +5,20 @@
  *
  *  Optimization changes Copyright (C) 1994 Florian La Roche
  *
+ *  Jun 7 1999, cache symlink lookups in the page cache.  -DaveM
+ *
  *  nfs symlink handling code
  */
 
+#define NFS_NEED_XDR_TYPES
 #include <linux/sched.h>
 #include <linux/errno.h>
+#include <linux/sunrpc/clnt.h>
 #include <linux/nfs_fs.h>
+#include <linux/nfs.h>
+#include <linux/pagemap.h>
 #include <linux/stat.h>
+#include <asm/pgtable.h>
 #include <linux/mm.h>
 #include <linux/malloc.h>
 #include <linux/string.h>
@@ -37,70 +44,85 @@
 	NULL,			/* rename */
 	nfs_readlink,		/* readlink */
 	nfs_follow_link,	/* follow_link */
+	NULL,			/* get_block */
 	NULL,			/* readpage */
 	NULL,			/* writepage */
-	NULL,			/* bmap */
+	NULL,			/* flushpage */
 	NULL,			/* truncate */
-	NULL			/* permission */
+	NULL,			/* permission */
+	NULL,			/* smap */
+	NULL			/* revalidate */
 };
 
+/* Symlink caching in the page cache is even more simplistic
+ * and straight-forward than readdir caching.
+ */
+static int nfs_symlink_filler(struct dentry *dentry, struct page *page)
+{
+	struct inode *inode = dentry->d_inode;
+	struct nfs_fattr fattr;
+	void * buffer = (void *)page_address(page);
+	unsigned int error;
+
+	/* We place the length at the beginning of the page,
+	 * in client byte order, followed by the string.
+	 */
+	error = NFS_CALL(readlink, inode, (dentry, &fattr, buffer,
+					   PAGE_CACHE_SIZE-sizeof(u32)-4));
+	nfs_refresh_inode(inode, &fattr);
+	if (error < 0)
+		goto error;
+	flush_dcache_page(page_address(page)); /* Is this correct? */
+	set_bit(PG_uptodate, &page->flags);
+	nfs_unlock_page(page);
+	return 0;
+error:
+	set_bit(PG_error, &page->flags);
+	nfs_unlock_page(page);
+	return -EIO;
+}
+
 static int nfs_readlink(struct dentry *dentry, char *buffer, int buflen)
 {
-	int error;
-	unsigned int len;
-	char *res;
-	void *mem;
-
-	dfprintk(VFS, "nfs: readlink(%s/%s)\n",
-		dentry->d_parent->d_name.name, dentry->d_name.name);
-
-	error = nfs_proc_readlink(NFS_DSERVER(dentry), NFS_FH(dentry),
-					&mem, &res, &len, NFS_MAXPATHLEN);
-	if (! error) {
-		if (len > buflen)
-			len = buflen;
-		copy_to_user(buffer, res, len);
-		error = len;
-		kfree(mem);
-	}
-	return error;
+	struct inode *inode = dentry->d_inode;
+	struct page *page;
+	u32 *p, len;
+
+	/* Caller revalidated the directory inode already. */
+	page = read_cache_page(inode, 0,
+				(filler_t *)nfs_symlink_filler, dentry);
+	if (IS_ERR(page))
+		goto read_failed;
+
+	p = (u32 *) page_address(page);
+	len = *p++;
+	if (len > buflen)
+		len = buflen;
+	copy_to_user(buffer, p, len);
+	page_cache_release(page);
+	return len;
+read_failed:
+	return PTR_ERR(page);
 }
 
 static struct dentry *
-nfs_follow_link(struct dentry * dentry, struct dentry *base, unsigned int follow)
+nfs_follow_link(struct dentry *dentry, struct dentry *base, unsigned int follow)
 {
-	int error;
-	unsigned int len;
-	char *res;
-	void *mem;
-	char *path;
 	struct dentry *result;
-
-	dfprintk(VFS, "nfs: follow_link(%s/%s)\n",
-		dentry->d_parent->d_name.name, dentry->d_name.name);
-
-	error = nfs_proc_readlink(NFS_DSERVER(dentry), NFS_FH(dentry),
-				 &mem, &res, &len, NFS_MAXPATHLEN);
-	result = ERR_PTR(error);
-	if (error)
-		goto out_dput;
-
-	result = ERR_PTR(-ENOMEM);
-	path = kmalloc(len + 1, GFP_KERNEL);
-	if (!path)
-		goto out_mem;
-	memcpy(path, res, len);
-	path[len] = 0;
-	kfree(mem);
-
-	result = lookup_dentry(path, base, follow);
-	kfree(path);
-out:
+	struct inode *inode = dentry->d_inode;
+	struct page *page;
+	u32 *p;
+
+	/* Caller revalidated the directory inode already. */
+	page = read_cache_page(inode, 0,
+				(filler_t *)nfs_symlink_filler, dentry);
+	if (IS_ERR(page))
+		goto read_failed;
+
+	p = (u32 *) page_address(page);
+	result = lookup_dentry((char *) (p + 1), base, follow);
+	page_cache_release(page);
 	return result;
-
-out_mem:
-	kfree(mem);
-out_dput:
-	dput(base);
-	goto out;
+read_failed:
+	return (struct dentry *)page;
 }