[PATCH v2 11/11] ext4: allow verity with fs block size < PAGE_SIZE

Eric Biggers
2022-12-23T20:37:24Z

From: Eric Biggers <ebiggers@google.com>

Now that the needed changes have been made to fs/buffer.c, ext4 is ready
to support the verity feature when the filesystem block size is less
than the page size. So remove the mount-time check that prevented this.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
Documentation/filesystems/fsverity.rst | 8 +++++---
fs/ext4/super.c | 5 -----
2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/Documentation/filesystems/fsverity.rst b/Documentation/filesystems/fsverity.rst
index 948d202545240..c0c8a25b41bb8 100644
--- a/Documentation/filesystems/fsverity.rst
+++ b/Documentation/filesystems/fsverity.rst
@@ -497,9 +497,11 @@ To create verity files on an ext4 filesystem, the filesystem must have
been formatted with ``-O verity`` or had ``tune2fs -O verity`` run on
it. "verity" is an RO_COMPAT filesystem feature, so once set, old
kernels will only be able to mount the filesystem readonly, and old
-versions of e2fsck will be unable to check the filesystem. Moreover,
-currently ext4 only supports mounting a filesystem with the "verity"
-feature when its block size is equal to PAGE_SIZE (often 4096 bytes).
+versions of e2fsck will be unable to check the filesystem.
+
+Originally, an ext4 filesystem with the "verity" feature could only be
+mounted when its block size was equal to the system page size
+(typically 4096 bytes). In Linux v6.3, this limitation was removed.

ext4 sets the EXT4_VERITY_FL on-disk inode flag on verity files. It
can only be set by `FS_IOC_ENABLE_VERITY`_, and it cannot be cleared.
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 16a343e8047d4..798cb19e2258b 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -5336,11 +5336,6 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
}
}

- if (ext4_has_feature_verity(sb) && sb->s_blocksize != PAGE_SIZE) {
- ext4_msg(sb, KERN_ERR, "Unsupported blocksize for fs-verity");
- goto failed_mount_wq;
- }
-
/*
* Get the # of file system overhead blocks from the
* superblock if present.
--
2.39.0