ext4: add fs-verity read support

Make ext4_mpage_readpages() verify data as it is read from fs-verity
files, using the helper functions from fs/verity/.

To support both encryption and verity simultaneously, this required
refactoring the decryption workflow into a generic "post-read
processing" workflow which can do decryption, verification, or both.

The case where the ext4 block size is not equal to the PAGE_SIZE is not
supported yet, since in that case ext4_mpage_readpages() sometimes falls
back to block_read_full_page(), which does not support fs-verity yet.

Co-developed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Eric Biggers <ebiggers@google.com>

1 files changed, 8 insertions, 1 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 05a9874687c3..23e7acd43e4e 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -6104,6 +6104,10 @@ static int __init ext4_init_fs(void)
 
 	err = ext4_init_pending();
 	if (err)
+		goto out7;
+
+	err = ext4_init_post_read_processing();
+	if (err)
 		goto out6;
 
 	err = ext4_init_pageio();
@@ -6144,8 +6148,10 @@ out3:
 out4:
 	ext4_exit_pageio();
 out5:
-	ext4_exit_pending();
+	ext4_exit_post_read_processing();
 out6:
+	ext4_exit_pending();
+out7:
 	ext4_exit_es();
 
 	return err;
@@ -6162,6 +6168,7 @@ static void __exit ext4_exit_fs(void)
 	ext4_exit_sysfs();
 	ext4_exit_system_zone();
 	ext4_exit_pageio();
+	ext4_exit_post_read_processing();
 	ext4_exit_es();
 	ext4_exit_pending();
 }