knfsd: exportfs: remove iget abuse

When the exportfs interface was added the expectation was that filesystems
provide an operation to convert from a file handle to an inode/dentry, but it
kept a backwards compat option that still calls into iget.

Calling into iget from non-filesystem code is very bad, because it gives too
little information to filesystem, and simply crashes if the filesystem doesn't
implement the ->read_inode routine.

Fortunately there are only two filesystems left using this fallback: efs and
jfs.  This patch moves a copy of export_iget to each of those to implement the
get_dentry method.

While this is a temporary increase of lines of code in the kernel it allows
for a much cleaner interface and important code restructuring in later
patches.

[akpm@linux-foundation.org: add jfs_get_inode_flags() declaration]
Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 53 deletions

diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index 16287af..dd132bb 100644
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -391,61 +391,11 @@ out:
 	return error;
 }
 
-
-static struct dentry *export_iget(struct super_block *sb, unsigned long ino, __u32 generation)
+static struct dentry *get_dentry(struct super_block *sb, void *vobjp)
 {
-
-	/* iget isn't really right if the inode is currently unallocated!!
-	 * This should really all be done inside each filesystem
-	 *
-	 * ext2fs' read_inode has been strengthed to return a bad_inode if
-	 * the inode had been deleted.
-	 *
-	 * Currently we don't know the generation for parent directory, so
-	 * a generation of 0 means "accept any"
-	 */
-	struct inode *inode;
-	struct dentry *result;
-	if (ino == 0)
-		return ERR_PTR(-ESTALE);
-	inode = iget(sb, ino);
-	if (inode == NULL)
-		return ERR_PTR(-ENOMEM);
-	if (is_bad_inode(inode)
-	    || (generation && inode->i_generation != generation)
-		) {
-		/* we didn't find the right inode.. */
-		dprintk("fh_verify: Inode %lu, Bad count: %d %d or version  %u %u\n",
-			inode->i_ino,
-			inode->i_nlink, atomic_read(&inode->i_count),
-			inode->i_generation,
-			generation);
-
-		iput(inode);
-		return ERR_PTR(-ESTALE);
-	}
-	/* now to find a dentry.
-	 * If possible, get a well-connected one
-	 */
-	result = d_alloc_anon(inode);
-	if (!result) {
-		iput(inode);
-		return ERR_PTR(-ENOMEM);
-	}
-	return result;
+	return ERR_PTR(-ESTALE);
 }
 
-
-static struct dentry *get_object(struct super_block *sb, void *vobjp)
-{
-	__u32 *objp = vobjp;
-	unsigned long ino = objp[0];
-	__u32 generation = objp[1];
-
-	return export_iget(sb, ino, generation);
-}
-
-
 /**
  * export_encode_fh - default export_operations->encode_fh function
  * @dentry:  the dentry to encode
@@ -524,7 +474,7 @@ struct export_operations export_op_default = {
 
 	.get_name	= get_name,
 	.get_parent	= get_parent,
-	.get_dentry	= get_object,
+	.get_dentry	= get_dentry,
 };
 
 EXPORT_SYMBOL(export_op_default);