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e2fsprogs: feature doc updates

PATCH New Eric Biggers 1 participant 7 messages Sep 20, 2019

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#0 lore raw

cover e2fsprogs: feature doc updates

Document the verity feature, and make some minor updates to the documentation for the encrypt and casefold features.

Eric Biggers (6):
ext4.5: move casefold feature to correct position ext4.5: document first kernel version to support casefold feature ext4.5: document the verity feature
ext4.5: tweak the documentation for the encrypt feature tune2fs.8: document the verity feature
tune2fs.8: tweak the documentation for the encrypt feature

 misc/ext4.5.in    | 38 +++++++++++++++++++++++++++-----------
 misc/tune2fs.8.in |  7 ++++++-
 2 files changed, 33 insertions(+), 12 deletions(-)
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#1 lore raw

PATCH 1/6 ext4.5: move casefold feature to correct position

From: Eric Biggers <[email protected]>

The features are listed in alphabetic order, so put the casefold feature in the right place.

---
 misc/ext4.5.in | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)
misc/ext4.5.in +8 -8
index 01dab48a..0a93c35e 100644
@@ -61,6 +61,14 @@ This feature requires that the
 .B extent
 feature be enabled.
 .TP
+.B casefold
+.br
+This ext4 feature provides file system level character encoding support
+for directories with the casefold (+F) flag enabled.  This feature is
+name-preserving on the disk, but it allows applications to lookup for a
+file in the file system using an encoding equivalent version of the file
+name.
+.TP
 .B dir_index
 .br
 Use hashed b-trees to speed up name lookups in large directories.  This
@@ -151,14 +159,6 @@ can be specified using the
 .B \-G
 option.
 .TP
-.B casefold
-.br
-This ext4 feature provides file system level character encoding support
-for directories with the casefold (+F) flag enabled.  This feature is
-name-preserving on the disk, but it allows applications to lookup for a
-file in the file system using an encoding equivalent version of the file
-name.
-.TP
 .B has_journal
 .br
 Create a journal to ensure filesystem consistency even across unclean
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#2 lore raw

PATCH 2/6 ext4.5: document first kernel version to support casefold feature

In reply to Eric Biggers

From: Eric Biggers <[email protected]>

---
 misc/ext4.5.in | 2 ++
 1 file changed, 2 insertions(+)
misc/ext4.5.in +2 -0
index 0a93c35e..40e75f81 100644
@@ -772,6 +772,8 @@ ext4, 4.5
 ext4, 4.13
 .IP "\fBlarge_dir\fR" 2i
 ext4, 4.13
+.IP "\fBcasefold\fR" 2i
+ext4, 5.2
 .SH SEE ALSO
 .BR mke2fs (8),
 .BR mke2fs.conf (5),
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#3 lore raw

PATCH 3/6 ext4.5: document the verity feature

In reply to Eric Biggers

From: Eric Biggers <[email protected]>

---
 misc/ext4.5.in | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
misc/ext4.5.in +14 -0
index 40e75f81..627c0dad 100644
@@ -312,6 +312,18 @@ the file system using
 and it also speeds up the time required for
 .BR mke2fs (8)
 to create the file system.
+.TP
+.B verity
+.br
+Enables support for verity protected files.  Verity files are readonly,
+and their data is transparently verified against a Merkle tree hidden
+past the end of the file.  Using the Merkle tree's root hash, a verity
+file can be efficiently authenticated, independent of the file's size.
+.IP
+This feature is most useful for authenticating important read-only files
+on read-write file systems.  If the file system itself is read-only,
+then using dm-verity to authenticate the entire block device may provide
+much better security.
 .SH MOUNT OPTIONS
 This section describes mount options which are specific to ext2, ext3,
 and ext4.  Other generic mount options may be used as well; see
@@ -774,6 +786,8 @@ ext4, 4.13
 ext4, 4.13
 .IP "\fBcasefold\fR" 2i
 ext4, 5.2
+.IP "\fBverity\fR" 2i
+ext4, 5.4
 .SH SEE ALSO
 .BR mke2fs (8),
 .BR mke2fs.conf (5),
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#4 lore raw

PATCH 4/6 ext4.5: tweak the documentation for the encrypt feature

In reply to Eric Biggers

From: Eric Biggers <[email protected]>

Try to make it clearer that enabling 'encrypt' just enables *support* for encryption; it doesn't actually encrypt anything by itself.

---
 misc/ext4.5.in | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
misc/ext4.5.in +3 -3
index 627c0dad..1db61a5f 100644
@@ -96,9 +96,9 @@ extended attributes per file.
 .TP
 .B encrypt
 .br
-This ext4 feature provides file-system level encryption of data blocks
-and file names.  The inode metadata (timestamps, file size, user/group
-ownership, etc.) is
+Enables support for file-system level encryption of data blocks and file
+names.  The inode metadata (timestamps, file size, user/group ownership,
+etc.) is
 .I not
 encrypted.
 .IP
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#5 lore raw

PATCH 5/6 tune2fs.8: document the verity feature

In reply to Eric Biggers

From: Eric Biggers <[email protected]>

---
 misc/tune2fs.8.in | 5 +++++
 1 file changed, 5 insertions(+)
misc/tune2fs.8.in +5 -0
index b60db6ed..f7c7d42d 100644
@@ -631,6 +631,11 @@ keep a high watermark for the unused inodes in a filesystem, to reduce
 time.  The first e2fsck run after enabling this feature will take the
 full time, but subsequent e2fsck runs will take only a fraction of the
 original time, depending on how full the file system is.
+.TP
+.B verity
+Enable support for verity protected files.
+.B Tune2fs
+currently only supports setting this filesystem feature.
 .RE
 .IP
 After setting or clearing
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#6 lore raw

PATCH 6/6 tune2fs.8: tweak the documentation for the encrypt feature

In reply to Eric Biggers

From: Eric Biggers <[email protected]>

Try to make it clearer that enabling 'encrypt' just enables *support* for encryption; it doesn't actually encrypt anything by itself.

---
 misc/tune2fs.8.in | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
misc/tune2fs.8.in +1 -1
index f7c7d42d..74eebb6a 100644
@@ -550,7 +550,7 @@ extended attributes per file.
 currently only supports setting this filesystem feature.
 .TP
 .B encrypt
-Enable file system level encryption.
+Enable support for file system level encryption.
 .B Tune2fs
 currently only supports setting this filesystem feature.
 .TP
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