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Date:   Mon, 18 May 2020 20:11:15 -0700
From:   Eric Biggers <ebiggers@kernel.org>
To:     Jaegeuk Kim <jaegeuk@kernel.org>
Cc:     "Theodore Y. Ts'o" <tytso@mit.edu>, linux-fscrypt@vger.kernel.org,
        linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net,
        Daniel Rosenberg <drosen@google.com>
Subject: Re: [PATCH 3/4] fscrypt: support test_dummy_encryption=v2
Message-ID: <20200519031115.GC954@sol.localdomain>
References: <20200512233251.118314-1-ebiggers@kernel.org>
 <20200512233251.118314-4-ebiggers@kernel.org>
 <20200519025355.GC2396055@mit.edu>
 <20200519030205.GB954@sol.localdomain>
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On Mon, May 18, 2020 at 08:02:05PM -0700, Eric Biggers wrote:
> On Mon, May 18, 2020 at 10:53:55PM -0400, Theodore Y. Ts'o wrote:
> > On Tue, May 12, 2020 at 04:32:50PM -0700, Eric Biggers wrote:
> > > From: Eric Biggers <ebiggers@google.com>
> > > 
> > > v1 encryption policies are deprecated in favor of v2, and some new
> > > features (e.g. encryption+casefolding) are only being added for v2.
> > > 
> > > Therefore, the "test_dummy_encryption" mount option (which is used for
> > > encryption I/O testing with xfstests) needs to support v2 policies.
> > > 
> > > To do this, extend its syntax to be "test_dummy_encryption=v1" or
> > > "test_dummy_encryption=v2".  The existing "test_dummy_encryption" (no
> > > argument) also continues to be accepted, to specify the default setting
> > > -- currently v1, but the next patch changes it to v2.
> > > 
> > > To cleanly support both v1 and v2 while also making it easy to support
> > > specifying other encryption settings in the future (say, accepting
> > > "$contents_mode:$filenames_mode:v2"), make ext4 and f2fs maintain a
> > > pointer to the dummy fscrypt_context rather than using mount flags.
> > > 
> > > To avoid concurrency issues, don't allow test_dummy_encryption to be set
> > > or changed during a remount.  (The former restriction is new, but
> > > xfstests doesn't run into it, so no one should notice.)
> > > 
> > > Tested with 'gce-xfstests -c {ext4,f2fs}/encrypt -g auto'.  On ext4,
> > > there are two regressions, both of which are test bugs: ext4/023 and
> > > ext4/028 fail because they set an xattr and expect it to be stored
> > > inline, but the increase in size of the fscrypt_context from
> > > 24 to 40 bytes causes this xattr to be spilled into an external block.
> > > 
> > > Signed-off-by: Eric Biggers <ebiggers@google.com>
> > 
> > Signed-off-by: Theodore Ts'o <tytso@mit.edu>
> > 
> > Looks good, but could you do me a favor and merge in this?
> > 
> > diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
> > index 04bfaf63752c..6c9fc9e21c13 100644
> > --- a/fs/ext4/sysfs.c
> > +++ b/fs/ext4/sysfs.c
> > @@ -293,6 +293,7 @@ EXT4_ATTR_FEATURE(batched_discard);
> >  EXT4_ATTR_FEATURE(meta_bg_resize);
> >  #ifdef CONFIG_FS_ENCRYPTION
> >  EXT4_ATTR_FEATURE(encryption);
> > +EXT4_ATTR_FEATURE(test_dummy_encryption_v2);
> >  #endif
> >  #ifdef CONFIG_UNICODE
> >  EXT4_ATTR_FEATURE(casefold);
> > @@ -308,6 +309,7 @@ static struct attribute *ext4_feat_attrs[] = {
> >  	ATTR_LIST(meta_bg_resize),
> >  #ifdef CONFIG_FS_ENCRYPTION
> >  	ATTR_LIST(encryption),
> > +	ATTR_LIST(test_dummy_encryption_v2),
> >  #endif
> >  #ifdef CONFIG_UNICODE
> >  	ATTR_LIST(casefold),
> > 
> > This will make it easier to have the gce-xfstests test runner know
> > whether or not test_dummy_encryption=v1 / test_dummy_encryption=v2
> > will work, and whether test_dummy_encryption tests v1 or v2.
> > 
> 
> Thanks, I'll add that.  I assume you meant "Reviewed-by"?

Jaegeuk, do you want /sys/fs/f2fs/features/test_dummy_encryption_v2 as well, to
match what Ted wants for ext4?  It would be the following change:

diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index e3bbbef9b4f09e4..3162f46b3c9bfc1 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -446,6 +446,7 @@ enum feat_id {
 	FEAT_SB_CHECKSUM,
 	FEAT_CASEFOLD,
 	FEAT_COMPRESSION,
+	FEAT_TEST_DUMMY_ENCRYPTION_V2,
 };
 
 static ssize_t f2fs_feature_show(struct f2fs_attr *a,
@@ -466,6 +467,7 @@ static ssize_t f2fs_feature_show(struct f2fs_attr *a,
 	case FEAT_SB_CHECKSUM:
 	case FEAT_CASEFOLD:
 	case FEAT_COMPRESSION:
+	case FEAT_TEST_DUMMY_ENCRYPTION_V2:
 		return sprintf(buf, "supported\n");
 	}
 	return 0;
@@ -563,6 +565,7 @@ F2FS_GENERAL_RO_ATTR(avg_vblocks);
 
 #ifdef CONFIG_FS_ENCRYPTION
 F2FS_FEATURE_RO_ATTR(encryption, FEAT_CRYPTO);
+F2FS_FEATURE_RO_ATTR(test_dummy_encryption_v2, FEAT_TEST_DUMMY_ENCRYPTION_V2);
 #endif
 #ifdef CONFIG_BLK_DEV_ZONED
 F2FS_FEATURE_RO_ATTR(block_zoned, FEAT_BLKZONED);
@@ -647,6 +650,7 @@ ATTRIBUTE_GROUPS(f2fs);
 static struct attribute *f2fs_feat_attrs[] = {
 #ifdef CONFIG_FS_ENCRYPTION
 	ATTR_LIST(encryption),
+	ATTR_LIST(test_dummy_encryption_v2),
 #endif
 #ifdef CONFIG_BLK_DEV_ZONED
 	ATTR_LIST(block_zoned),