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| author | Eric Biggers <ebiggers@google.com> | 2019-12-26 09:42:16 -0600 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2020-01-17 16:24:53 -0500 |
| commit | 457b1e353c739af39159269723949f315320446c (patch) | |
| tree | ec525088a9681a576df030b7871b423bdda07bd4 /Documentation/filesystems | |
| parent | 834f1565fa3f9c8f78adbfcaa80ae510fe4971c3 (diff) | |
| download | talos-op-linux-457b1e353c739af39159269723949f315320446c.tar.gz talos-op-linux-457b1e353c739af39159269723949f315320446c.zip | |
ext4: allow ZERO_RANGE on encrypted files
When ext4 encryption support was first added, ZERO_RANGE was disallowed,
supposedly because test failures (e.g. ext4/001) were seen when enabling
it, and at the time there wasn't enough time/interest to debug it.
However, there's actually no reason why ZERO_RANGE can't work on
encrypted files. And it fact it *does* work now. Whole blocks in the
zeroed range are converted to unwritten extents, as usual; encryption
makes no difference for that part. Partial blocks are zeroed in the
pagecache and then ->writepages() encrypts those blocks as usual.
ext4_block_zero_page_range() handles reading and decrypting the block if
needed before actually doing the pagecache write.
Also, f2fs has always supported ZERO_RANGE on encrypted files.
As far as I can tell, the reason that ext4/001 was failing in v4.1 was
actually because of one of the bugs fixed by commit 36086d43f657 ("ext4
crypto: fix bugs in ext4_encrypted_zeroout()"). The bug made
ext4_encrypted_zeroout() always return a positive value, which caused
unwritten extents in encrypted files to sometimes not be marked as
initialized after being written to. This bug was not actually in
ZERO_RANGE; it just happened to trigger during the extents manipulation
done in ext4/001 (and probably other tests too).
So, let's enable ZERO_RANGE on encrypted files on ext4.
Tested with:
gce-xfstests -c ext4/encrypt -g auto
gce-xfstests -c ext4/encrypt_1k -g auto
Got the same set of test failures both with and without this patch.
But with this patch 6 fewer tests are skipped: ext4/001, generic/008,
generic/009, generic/033, generic/096, and generic/511.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20191226154216.4808-1-ebiggers@kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/fscrypt.rst | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst index 68c2bc8275cf..07f1f15276bf 100644 --- a/Documentation/filesystems/fscrypt.rst +++ b/Documentation/filesystems/fscrypt.rst @@ -975,9 +975,9 @@ astute users may notice some differences in behavior: - Direct I/O is not supported on encrypted files. Attempts to use direct I/O on such files will fall back to buffered I/O. -- The fallocate operations FALLOC_FL_COLLAPSE_RANGE, - FALLOC_FL_INSERT_RANGE, and FALLOC_FL_ZERO_RANGE are not supported - on encrypted files and will fail with EOPNOTSUPP. +- The fallocate operations FALLOC_FL_COLLAPSE_RANGE and + FALLOC_FL_INSERT_RANGE are not supported on encrypted files and will + fail with EOPNOTSUPP. - Online defragmentation of encrypted files is not supported. The EXT4_IOC_MOVE_EXT and F2FS_IOC_MOVE_RANGE ioctls will fail with |
