From: J. Bruce Fields <bfields@redhat.com>
Date: Tue, 10 Sep 2013 15:41:12 +0000 (-0400)
Subject: exportfs: fix 32-bit nfsd handling of 64-bit inode numbers
X-Git-Tag: firefly_0821_release~176^2~4994^2~27
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=950ee9566a5b6cc45d15f5fe044bab4f1e8b62cb;p=firefly-linux-kernel-4.4.55.git

exportfs: fix 32-bit nfsd handling of 64-bit inode numbers

Symptoms were spurious -ENOENTs on stat of an NFS filesystem from a
32-bit NFS server exporting a very large XFS filesystem, when the
server's cache is cold (so the inodes in question are not in cache).

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reported-by: Trevor Cordes <trevor@tecnopolis.ca>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---

diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index a235f0016889..c43fe9b39ff2 100644
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -215,7 +215,7 @@ struct getdents_callback {
 	struct dir_context ctx;
 	char *name;		/* name that was found. It already points to a
 				   buffer NAME_MAX+1 is size */
-	unsigned long ino;	/* the inum we are looking for */
+	u64 ino;		/* the inum we are looking for */
 	int found;		/* inode matched? */
 	int sequence;		/* sequence counter */
 };
@@ -255,10 +255,14 @@ static int get_name(const struct path *path, char *name, struct dentry *child)
 	struct inode *dir = path->dentry->d_inode;
 	int error;
 	struct file *file;
+	struct kstat stat;
+	struct path child_path = {
+		.mnt = path->mnt,
+		.dentry = child,
+	};
 	struct getdents_callback buffer = {
 		.ctx.actor = filldir_one,
 		.name = name,
-		.ino = child->d_inode->i_ino
 	};
 
 	error = -ENOTDIR;
@@ -267,6 +271,16 @@ static int get_name(const struct path *path, char *name, struct dentry *child)
 	error = -EINVAL;
 	if (!dir->i_fop)
 		goto out;
+	/*
+	 * inode->i_ino is unsigned long, kstat->ino is u64, so the
+	 * former would be insufficient on 32-bit hosts when the
+	 * filesystem supports 64-bit inode numbers.  So we need to
+	 * actually call ->getattr, not just read i_ino:
+	 */
+	error = vfs_getattr_nosec(&child_path, &stat);
+	if (error)
+		return error;
+	buffer.ino = stat.ino;
 	/*
 	 * Open the directory ...
 	 */