Hi Eric,
On 2018/3/29 2:15, Eric Biggers wrote:
> Reserve an F2FS feature flag and inode flag for fs-verity. This is an
> in-development feature that is planned be discussed at LSF/MM 2018 [1].
> It will provide file-based integrity and authenticity for read-only
> files. Most code will be in a filesystem-independent module, with
> smaller changes needed to individual filesystems that opt-in to
> supporting the feature. An early prototype supporting F2FS is available
> [2]. Reserving the F2FS on-disk bits for fs-verity will prevent users
> of the prototype from conflicting with other new F2FS features.
>
> Note that we're reserving the inode flag in f2fs_inode.i_advise, which
> isn't really appropriate since it's not a hint or advice. But
> ->i_advise is already being used to hold the 'encrypt' flag; and F2FS's
> ->i_flags uses the generic FS_* values, so it seems ->i_flags can't be
> used for an F2FS-specific flag without additional work to remove the
> assumption that ->i_flags uses the generic flags namespace.
At a glance, this is a VFS feature, can we search free slot, and define
FS_VERITY_FL like other generic flags, so we can intergrate this flag into
f2fs_inode::i_flags?
And how about applying this patch inside the patchset of new fsverity feature?
Since once fsverity feature has some design modification, I worry about that may
be we need to change this bit? result in disk layout incompatibility.
Thanks,
>
> [1] https://marc.info/?l=linux-fsdevel&m=151690752225644
> [2] https://git.kernel.org/pub/scm/linux/kernel/git/mhalcrow/linux.git/log/?h=fs-verity-dev
>
> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
> ---
> fs/f2fs/f2fs.h | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index ae69dc358401..96d7809c4541 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -146,6 +146,7 @@ struct f2fs_mount_info {
> #define F2FS_FEATURE_QUOTA_INO 0x0080
> #define F2FS_FEATURE_INODE_CRTIME 0x0100
> #define F2FS_FEATURE_LOST_FOUND 0x0200
> +#define F2FS_FEATURE_VERITY 0x0400 /* reserved */
>
> #define F2FS_HAS_FEATURE(sb, mask) \
> ((F2FS_SB(sb)->raw_super->feature & cpu_to_le32(mask)) != 0)
> @@ -598,6 +599,7 @@ enum {
> #define FADVISE_ENC_NAME_BIT 0x08
> #define FADVISE_KEEP_SIZE_BIT 0x10
> #define FADVISE_HOT_BIT 0x20
> +#define FADVISE_VERITY_BIT 0x40 /* reserved */
>
> #define file_is_cold(inode) is_file(inode, FADVISE_COLD_BIT)
> #define file_wrong_pino(inode) is_file(inode, FADVISE_LOST_PINO_BIT)
>
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