From: Eric Biggers <ebiggers@xxxxxxxxxx>
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@xxxxxxxxxx>
---
Documentation/filesystems/fscrypt.rst | 6 +++---
fs/ext4/extents.c | 7 +------
2 files changed, 4 insertions(+), 9 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
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 0e8708b77da6..dae66e8f0c3a 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4890,14 +4890,9 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
* range since we would need to re-encrypt blocks with a
* different IV or XTS tweak (which are based on the logical
* block number).
- *
- * XXX It's not clear why zero range isn't working, but we'll
- * leave it disabled for encrypted inodes for now. This is a
- * bug we should fix....
*/
if (IS_ENCRYPTED(inode) &&
- (mode & (FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_INSERT_RANGE |
- FALLOC_FL_ZERO_RANGE)))
+ (mode & (FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_INSERT_RANGE)))
return -EOPNOTSUPP;
/* Return error if mode is not supported */
--
2.24.1
