ext4: reserve inodes and feature code for 'quota' feature

I am working on patch to add quota as a built-in feature for ext4
filesystem. The implementation is based on the design given at
https://ext4.wiki.kernel.org/index.php/Design_For_1st_Class_Quota_in_Ext4.
This patch reserves the inode numbers 3 and 4 for quota purposes and
also reserves EXT4_FEATURE_RO_COMPAT_QUOTA feature code.

Signed-off-by: Aditya Kali <adityakali@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index c0c56c9d5933..2bc4c21f1d26 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -209,6 +209,8 @@ struct ext4_io_submit {
  */
 #define EXT4_BAD_INO             1      /* Bad blocks inode */
 #define EXT4_ROOT_INO            2      /* Root inode */
+#define EXT4_USR_QUOTA_INO       3      /* User quota inode */
+#define EXT4_GRP_QUOTA_INO       4      /* Group quota inode */
 #define EXT4_BOOT_LOADER_INO     5      /* Boot loader inode */
 #define EXT4_UNDEL_DIR_INO       6      /* Undelete directory inode */
 #define EXT4_RESIZE_INO          7      /* Reserved group descriptors inode */
@@ -1344,6 +1346,7 @@ static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
 #define EXT4_FEATURE_RO_COMPAT_GDT_CSUM         0x0010
 #define EXT4_FEATURE_RO_COMPAT_DIR_NLINK        0x0020
 #define EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE      0x0040
+#define EXT4_FEATURE_RO_COMPAT_QUOTA            0x0100
 
 #define EXT4_FEATURE_INCOMPAT_COMPRESSION       0x0001
 #define EXT4_FEATURE_INCOMPAT_FILETYPE          0x0002