RE: [PATCH] path_lookup for 2.4.20-pre4 (ChangeSet@1.587.10.71)

[Trond Myklebust <trond.myklebust@fys.uio.no>]

This patch breaks NFS close-to-open cache consistency as it undoes
those changes that provide path revalidation for the case of
open(".").
The changelog entry doesn't even attempt to document this removal...

If people want to revert to the old behaviour, then there are ways of
doing this that will not affect NFS. Something like the appended patch
for instance...

Cheers,
  Trond

diff -u --recursive --new-file linux-2.4.22-odirect/fs/namei.c linux-2.4.22-fix_cto/fs/namei.c
--- linux-2.4.22-odirect/fs/namei.c	2003-06-27 13:34:41.000000000 +0200
+++ linux-2.4.22-fix_cto/fs/namei.c	2003-07-08 15:51:08.000000000 +0200
@@ -563,7 +563,7 @@
 	while (*name=='/')
 		name++;
 	if (!*name)
-		goto return_base;
+		goto return_reval;
 
 	inode = nd->dentry->d_inode;
 	if (current->link_count)
@@ -686,7 +686,7 @@
 				inode = nd->dentry->d_inode;
 				/* fallthrough */
 			case 1:
-				goto return_base;
+				goto return_reval;
 		}
 		if (nd->dentry->d_op && nd->dentry->d_op->d_hash) {
 			err = nd->dentry->d_op->d_hash(nd->dentry, &this);
@@ -732,6 +732,24 @@
 			nd->last_type = LAST_DOT;
 		else if (this.len == 2 && this.name[1] == '.')
 			nd->last_type = LAST_DOTDOT;
+return_reval:
+		/*
+		 * We bypassed the ordinary revalidation routines.
+		 * We may need to check the cached dentry for staleness.
+		 */
+		if (nd->dentry && nd->dentry->d_sb &&
+		    (nd->dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) {
+			struct dentry *dentry = nd->dentry;
+			unlock_nd(nd);
+			dput(pinned.dentry);
+			mntput(pinned.mnt);
+			if (!dentry->d_op->d_revalidate(dentry, 0)) {
+				d_invalidate(dentry);
+				path_release(nd);
+				return -ESTALE;
+			}
+			return 0;
+		}
 return_base:
 		unlock_nd(nd);
 		dput(pinned.dentry);
diff -u --recursive --new-file linux-2.4.22-odirect/fs/nfs/inode.c linux-2.4.22-fix_cto/fs/nfs/inode.c
--- linux-2.4.22-odirect/fs/nfs/inode.c	2002-08-15 03:05:32.000000000 +0200
+++ linux-2.4.22-fix_cto/fs/nfs/inode.c	2003-07-08 15:24:32.000000000 +0200
@@ -1125,7 +1125,7 @@
 /*
  * File system information
  */
-static DECLARE_FSTYPE(nfs_fs_type, "nfs", nfs_read_super, FS_ODD_RENAME);
+static DECLARE_FSTYPE(nfs_fs_type, "nfs", nfs_read_super, FS_ODD_RENAME|FS_REVAL_DOT);
 
 extern int nfs_init_nfspagecache(void);
 extern void nfs_destroy_nfspagecache(void);
diff -u --recursive --new-file linux-2.4.22-odirect/include/linux/fs.h linux-2.4.22-fix_cto/include/linux/fs.h
--- linux-2.4.22-odirect/include/linux/fs.h	2003-07-08 11:47:08.000000000 +0200
+++ linux-2.4.22-fix_cto/include/linux/fs.h	2003-07-08 15:47:06.000000000 +0200
@@ -92,6 +92,7 @@
 #define FS_SINGLE	8 /* Filesystem that can have only one superblock */
 #define FS_NOMOUNT	16 /* Never mount from userland */
 #define FS_LITTER	32 /* Keeps the tree in dcache */
+#define FS_REVAL_DOT	16384	/* Check the paths ".", ".." for staleness */
 #define FS_ODD_RENAME	32768	/* Temporary stuff; will go away as soon
 				  * as nfs_rename() will be cleaned up
 				  */