From 219db95bbe796277c739cca17fe134f6c2ce6676 Mon Sep 17 00:00:00 2001 From: Ayush Ranjan Date: Thu, 22 Aug 2019 23:18:33 -0400 Subject: ext4: documentation fixes This commit aims to fix the following issues in ext4 documentation: - Flexible block group docs said that the aim was to group block metadata together instead of block group metadata. - The documentation consistly uses "location" instead of "block number". It is easy to confuse location to be an absolute offset on disk. Added a line to clarify all location values are in terms of block numbers. - Dirent2 docs said that the rec_len field is shortened instead of the name_len field. - Typo in bg_checksum description. - Inode size is 160 bytes now, and hence i_extra_isize is now 32. - Cluster size formula was incorrect, it did not include the +10 to s_log_cluster_size value. - Typo: there were two s_wtime_hi in the superblock struct. - Superblock struct was outdated, added the new fields which were part of s_reserved earlier. - Multiple mount protection seems to be implemented in fs/ext4/mmp.c. Signed-off-by: Ayush Ranjan Signed-off-by: Theodore Ts'o Reviewed-by: Andreas Dilger --- Documentation/filesystems/ext4/super.rst | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) (limited to 'Documentation/filesystems/ext4/super.rst') diff --git a/Documentation/filesystems/ext4/super.rst b/Documentation/filesystems/ext4/super.rst index 04ff079a2acf..48b6c78fc38e 100644 --- a/Documentation/filesystems/ext4/super.rst +++ b/Documentation/filesystems/ext4/super.rst @@ -58,7 +58,7 @@ The ext4 superblock is laid out as follows in * - 0x1C - \_\_le32 - s\_log\_cluster\_size - - Cluster size is (2 ^ s\_log\_cluster\_size) blocks if bigalloc is + - Cluster size is 2 ^ (10 + s\_log\_cluster\_size) blocks if bigalloc is enabled. Otherwise s\_log\_cluster\_size must equal s\_log\_block\_size. * - 0x20 - \_\_le32 @@ -447,7 +447,7 @@ The ext4 superblock is laid out as follows in - Upper 8 bits of the s_wtime field. * - 0x275 - \_\_u8 - - s\_wtime_hi + - s\_mtime_hi - Upper 8 bits of the s_mtime field. * - 0x276 - \_\_u8 @@ -466,12 +466,20 @@ The ext4 superblock is laid out as follows in - s\_last_error_time_hi - Upper 8 bits of the s_last_error_time_hi field. * - 0x27A - - \_\_u8[2] - - s\_pad + - \_\_u8 + - s\_pad[2] - Zero padding. * - 0x27C + - \_\_le16 + - s\_encoding + - Filename charset encoding. + * - 0x27E + - \_\_le16 + - s\_encoding_flags + - Filename charset encoding flags. + * - 0x280 - \_\_le32 - - s\_reserved[96] + - s\_reserved[95] - Padding to the end of the block. * - 0x3FC - \_\_le32 @@ -617,7 +625,7 @@ following: * - 0x80 - Enable a filesystem size of 2^64 blocks (INCOMPAT\_64BIT). * - 0x100 - - Multiple mount protection. Not implemented (INCOMPAT\_MMP). + - Multiple mount protection (INCOMPAT\_MMP). * - 0x200 - Flexible block groups. See the earlier discussion of this feature (INCOMPAT\_FLEX\_BG). -- cgit v1.2.3