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.
[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)
--
2.17.0.rc1.321.gba9d0f2565-goog
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