From: Darrick J. Wong <djwong@xxxxxxxxxx> Document the exact byte transformations that happen during directory name lookup when the version=ci feature is enabled. Warn that this is not generally compatible, and that people should not use this feature. Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> --- man/man8/mkfs.xfs.8.in | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) diff --git a/man/man8/mkfs.xfs.8.in b/man/man8/mkfs.xfs.8.in index 49e64d47ae4..6fc7708bc94 100644 --- a/man/man8/mkfs.xfs.8.in +++ b/man/man8/mkfs.xfs.8.in @@ -809,11 +809,25 @@ can be either 2 or 'ci', defaulting to 2 if unspecified. With version 2 directories, the directory block size can be any power of 2 size from the filesystem block size up to 65536. .IP -The +If the .B version=ci -option enables ASCII only case-insensitive filename lookup and version -2 directories. Filenames are case-preserving, that is, the names -are stored in directories using the case they were created with. +option is specified, the kernel will transform certain bytes in filenames +before performing lookup-related operations. +The byte sequence given to create a directory entry is persisted without +alterations. +The lookup transformations are defined as follows: + + 0x41-0x5a -> 0x61-0x7a + + 0xc0-0xd6 -> 0xe0-0xf6 + + 0xd8-0xde -> 0xf8-0xfe + +This transformation roughly corresponds to case insensitivity in ISO +8859-1. +The transformations are not compatible with other encodings (e.g. UTF8). +Do not enable this feature unless your entire environment has been coerced +to ISO 8859-1. .IP Note: Version 1 directories are not supported. .TP
