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Documentation: ext4: Document casefold and encrypt flags

PATCH Applied Daniel Tang 2 participants 2 messages Nov 19, 2025 – Dec 1, 2025

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Documentation ext4 file system
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Daniel Tang

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PATCH 1/1 Documentation: ext4: Document casefold and encrypt flags

Based on ext4(5) and fs/ext4/ext4.h.

For INCOMPAT_ENCRYPT, it's possible to create a new filesystem with that flag without creating any encrypted inodes. ext4(5) says it adds "support" but doesn't say whether anything's actually present like COMPAT_RESIZE_INODE does.

Signed-off-by Daniel Tang <[email protected]>
---
 Documentation/filesystems/ext4/inodes.rst | 2 ++
 Documentation/filesystems/ext4/super.rst  | 4 +++-
 2 files changed, 5 insertions(+), 1 deletion(-)
Documentation/filesystems/ext4/inodes.rst +2 -0
index cfc6c1659931..55cd5c380e92 100644
@@ -297,6 +297,8 @@ The ``i_flags`` field is a combination of these values:
      - Inode has inline data (EXT4_INLINE_DATA_FL).
    * - 0x20000000
      - Create children with the same project ID (EXT4_PROJINHERIT_FL).
+   * - 0x40000000
+     - Use case-insensitive lookups for directory contents (EXT4_CASEFOLD_FL).
    * - 0x80000000
      - Reserved for ext4 library (EXT4_RESERVED_FL).
    * -
Documentation/filesystems/ext4/super.rst +3 -1
index 1b240661bfa3..9a59cded9bd7 100644
@@ -671,7 +671,9 @@ following:
    * - 0x8000
      - Data in inode (INCOMPAT_INLINE_DATA).
    * - 0x10000
-     - Encrypted inodes are present on the filesystem. (INCOMPAT_ENCRYPT).
+     - Encrypted inodes can be present. (INCOMPAT_ENCRYPT).
+   * - 0x20000
+     - Directories can be marked case-insensitive. (INCOMPAT_CASEFOLD).
 
 .. _super_rocompat:
Signature · 1 line
2.51.0
maintainer Applied
#1 lore raw
Quoted 8 lines · Daniel Tang

Based on ext4(5) and fs/ext4/ext4.h.

For INCOMPAT_ENCRYPT, it's possible to create a new filesystem with that flag without creating any encrypted inodes. ext4(5) says it adds "support" but doesn't say whether anything's actually present like COMPAT_RESIZE_INODE does.

[...]

Applied, thanks!

[1/1] Documentation: ext4: Document casefold and encrypt flags

      commit: 39fc6d4d3527d790f090dcb10bdb82fd1a1d925a

Best regards,

Signature · 1 line
Theodore Ts'o <[email protected]>