From: Gabriel Krisman Bertazi <krisman@collabora.com>
Date: Mon, 25 Oct 2021 19:27:29 +0000 (-0300)
Subject: fanotify: Allow file handle encoding for unhashed events
X-Git-Tag: v5.15.154~519
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=5f34524dde58da31d3e23a7598ac31c5a54f21ae;p=thirdparty%2Fkernel%2Fstable.git

fanotify: Allow file handle encoding for unhashed events

[ Upstream commit 74fe4734897a2da2ae2a665a5e622cd490d36eaf ]

Allow passing a NULL hash to fanotify_encode_fh and avoid calculating
the hash if not needed.

Link: https://lore.kernel.org/r/20211025192746.66445-15-krisman@collabora.com
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 397ee623ff1e8..ec84fee7ad01c 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -403,8 +403,12 @@ static int fanotify_encode_fh(struct fanotify_fh *fh, struct inode *inode,
 	fh->type = type;
 	fh->len = fh_len;
 
-	/* Mix fh into event merge key */
-	*hash ^= fanotify_hash_fh(fh);
+	/*
+	 * Mix fh into event merge key.  Hash might be NULL in case of
+	 * unhashed FID events (i.e. FAN_FS_ERROR).
+	 */
+	if (hash)
+		*hash ^= fanotify_hash_fh(fh);
 
 	return FANOTIFY_FH_HDR_LEN + fh_len;