[PATCH] Documentation: ext4: Add fields to ext4_super_block documentation

[PATCH] Documentation: ext4: Add fields to ext4_super_block documentation

[Tom Vierjahn]

Documentation and implementation of the ext4 super block have
slightly diverged: Padding has been removed in order to make room for
new fields that are still missing in the documentation.

Add the new fields s_encryption_level, s_first_error_errorcode,
s_last_error_errorcode to the documentation of the ext4 super block.

Fixes: f542fbe8d5e8 ("ext4 crypto: reserve codepoints used by the ext4 encryption feature")
Fixes: 878520ac45f9 ("ext4: save the error code which triggered an ext4_error() in the superblock")

Signed-off-by: Tom Vierjahn <tom.vierjahn@acm.org>
---
 Documentation/filesystems/ext4/super.rst | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/Documentation/filesystems/ext4/super.rst b/Documentation/filesystems/ext4/super.rst
index a1eb4a11a1d0..1b240661bfa3 100644
--- a/Documentation/filesystems/ext4/super.rst
+++ b/Documentation/filesystems/ext4/super.rst
@@ -328,9 +328,13 @@ The ext4 superblock is laid out as follows in
      - s_checksum_type
      - Metadata checksum algorithm type. The only valid value is 1 (crc32c).
    * - 0x176
-     - __le16
-     - s_reserved_pad
-     -
+     - \_\_u8
+     - s\_encryption\_level
+     - Versioning level for encryption.
+   * - 0x177
+     - \_\_u8
+     - s\_reserved\_pad
+     - Padding to next 32bits.
    * - 0x178
      - __le64
      - s_kbytes_written
@@ -466,9 +470,13 @@ The ext4 superblock is laid out as follows in
      - s_last_error_time_hi
      - Upper 8 bits of the s_last_error_time field.
    * - 0x27A
-     - __u8
-     - s_pad[2]
-     - Zero padding.
+     - \_\_u8
+     - s\_first\_error\_errcode
+     -
+   * - 0x27B
+     - \_\_u8
+     - s\_last\_error\_errcode
+     -
    * - 0x27C
      - __le16
      - s_encoding

base-commit: d5e206778e96e8667d3bde695ad372c296dc9353
-- 
2.49.0

Re: [PATCH] Documentation: ext4: Add fields to ext4_super_block documentation

[Ojaswin Mujoo]

On Mon, Mar 24, 2025 at 11:09:30PM +0100, Tom Vierjahn wrote:
> Documentation and implementation of the ext4 super block have
> slightly diverged: Padding has been removed in order to make room for
> new fields that are still missing in the documentation.
> 
> Add the new fields s_encryption_level, s_first_error_errorcode,
> s_last_error_errorcode to the documentation of the ext4 super block.
> 
> Fixes: f542fbe8d5e8 ("ext4 crypto: reserve codepoints used by the ext4 encryption feature")
> Fixes: 878520ac45f9 ("ext4: save the error code which triggered an ext4_error() in the superblock")
> 
> Signed-off-by: Tom Vierjahn <tom.vierjahn@acm.org>

Looks good, thanks for updating the docs.

Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>

Regards,
ojaswin
> ---
>  Documentation/filesystems/ext4/super.rst | 20 ++++++++++++++------
>  1 file changed, 14 insertions(+), 6 deletions(-)
> 
> diff --git a/Documentation/filesystems/ext4/super.rst b/Documentation/filesystems/ext4/super.rst
> index a1eb4a11a1d0..1b240661bfa3 100644
> --- a/Documentation/filesystems/ext4/super.rst
> +++ b/Documentation/filesystems/ext4/super.rst
> @@ -328,9 +328,13 @@ The ext4 superblock is laid out as follows in
>       - s_checksum_type
>       - Metadata checksum algorithm type. The only valid value is 1 (crc32c).
>     * - 0x176
> -     - __le16
> -     - s_reserved_pad
> -     -
> +     - \_\_u8
> +     - s\_encryption\_level
> +     - Versioning level for encryption.
> +   * - 0x177
> +     - \_\_u8
> +     - s\_reserved\_pad
> +     - Padding to next 32bits.
>     * - 0x178
>       - __le64
>       - s_kbytes_written
> @@ -466,9 +470,13 @@ The ext4 superblock is laid out as follows in
>       - s_last_error_time_hi
>       - Upper 8 bits of the s_last_error_time field.
>     * - 0x27A
> -     - __u8
> -     - s_pad[2]
> -     - Zero padding.
> +     - \_\_u8
> +     - s\_first\_error\_errcode
> +     -
> +   * - 0x27B
> +     - \_\_u8
> +     - s\_last\_error\_errcode
> +     -
>     * - 0x27C
>       - __le16
>       - s_encoding
> 
> base-commit: d5e206778e96e8667d3bde695ad372c296dc9353
> -- 
> 2.49.0
> 

Re: [PATCH] Documentation: ext4: Add fields to ext4_super_block documentation

[Theodore Ts'o]

On Mon, 24 Mar 2025 23:09:30 +0100, Tom Vierjahn wrote:
> Documentation and implementation of the ext4 super block have
> slightly diverged: Padding has been removed in order to make room for
> new fields that are still missing in the documentation.
> 
> Add the new fields s_encryption_level, s_first_error_errorcode,
> s_last_error_errorcode to the documentation of the ext4 super block.
> 
> [...]

Applied, thanks!

[1/1] Documentation: ext4: Add fields to ext4_super_block documentation
      commit: ce7e8a65aa1b7e8a6833403b314fa8f2cf133119

(Apologies for sending this late; I've been dealing with a family
medical emergency.  In any case, the patch landed in v6.16-rc2.)

Best regards,
-- 
Theodore Ts'o <tytso@mit.edu>