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authorEric Biggers <ebiggers@google.com>2019-12-26 09:42:16 -0600
committerTheodore Ts'o <tytso@mit.edu>2020-01-17 16:24:53 -0500
commit457b1e353c739af39159269723949f315320446c (patch)
treeec525088a9681a576df030b7871b423bdda07bd4
parent834f1565fa3f9c8f78adbfcaa80ae510fe4971c3 (diff)
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>
-rw-r--r--Documentation/filesystems/fscrypt.rst6
-rw-r--r--fs/ext4/extents.c7
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 a7f90470b1dc..4ba8215fa288 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4891,14 +4891,9 @@ 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 */