1 files changed, 13 insertions, 11 deletions

diff --git a/fs/verity/enable.c b/fs/verity/enable.c
index 1370bfd17e87..39459b1eff75 100644
--- a/fs/verity/enable.c
+++ b/fs/verity/enable.c
@@ -350,25 +350,27 @@ int fsverity_ioctl_enable(struct file *filp, const void __user *uarg)
 		goto out_drop_write;
 
 	err = enable_verity(filp, &arg);
-	if (err)
-		goto out_allow_write_access;
 
 	/*
-	 * Some pages of the file may have been evicted from pagecache after
-	 * being used in the Merkle tree construction, then read into pagecache
-	 * again by another process reading from the file concurrently.  Since
-	 * these pages didn't undergo verification against the file measurement
-	 * which fs-verity now claims to be enforcing, we have to wipe the
-	 * pagecache to ensure that all future reads are verified.
+	 * We no longer drop the inode's pagecache after enabling verity.  This
+	 * used to be done to try to avoid a race condition where pages could be
+	 * evicted after being used in the Merkle tree construction, then
+	 * re-instantiated by a concurrent read.  Such pages are unverified, and
+	 * the backing storage could have filled them with different content, so
+	 * they shouldn't be used to fulfill reads once verity is enabled.
+	 *
+	 * But, dropping the pagecache has a big performance impact, and it
+	 * doesn't fully solve the race condition anyway.  So for those reasons,
+	 * and also because this race condition isn't very important relatively
+	 * speaking (especially for small-ish files, where the chance of a page
+	 * being used, evicted, *and* re-instantiated all while enabling verity
+	 * is quite small), we no longer drop the inode's pagecache.
 	 */
-	filemap_write_and_wait(inode->i_mapping);
-	invalidate_inode_pages2(inode->i_mapping);
 
 	/*
 	 * allow_write_access() is needed to pair with deny_write_access().
 	 * Regardless, the filesystem won't allow writing to verity files.
 	 */
-out_allow_write_access:
 	allow_write_access(filp);
 out_drop_write:
 	mnt_drop_write_file(filp);