[XFS] XFS: ASCII case-insensitive support

Implement ASCII case-insensitive support. It's primary purpose is for
supporting existing filesystems that already use this case-insensitive
mode migrated from IRIX. But, if you only need ASCII-only case-insensitive
support (ie. English only) and will never use another language, then this
mode is perfectly adequate.

ASCII-CI is implemented by generating hashes based on lower-case letters
and doing lower-case compares. It implements a new xfs_nameops vector for
doing the hashes and comparisons for all filename operations.

To create a filesystem with this CI mode, use: # mkfs.xfs -n version=ci
<device>

SGI-PV: 981516
SGI-Modid: xfs-linux-melb:xfs-kern:31209a

Signed-off-by: Barry Naujok <bnaujok@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>

1 files changed, 9 insertions, 1 deletions

diff --git a/fs/xfs/xfs_sb.h b/fs/xfs/xfs_sb.h
index e3204a36a222..3f8cf1587f4c 100644
--- a/fs/xfs/xfs_sb.h
+++ b/fs/xfs/xfs_sb.h
@@ -46,10 +46,12 @@ struct xfs_mount;
 #define XFS_SB_VERSION_SECTORBIT        0x0800
 #define XFS_SB_VERSION_EXTFLGBIT        0x1000
 #define XFS_SB_VERSION_DIRV2BIT         0x2000
+#define XFS_SB_VERSION_BORGBIT          0x4000  /* ASCII only case-insens. */
 #define XFS_SB_VERSION_MOREBITSBIT      0x8000
 #define XFS_SB_VERSION_OKSASHFBITS      \
         (XFS_SB_VERSION_EXTFLGBIT | \
-         XFS_SB_VERSION_DIRV2BIT)
+         XFS_SB_VERSION_DIRV2BIT | \
+         XFS_SB_VERSION_BORGBIT)
 #define XFS_SB_VERSION_OKREALFBITS      \
         (XFS_SB_VERSION_ATTRBIT | \
          XFS_SB_VERSION_NLINKBIT | \
@@ -437,6 +439,12 @@ static inline int xfs_sb_version_hassector(xfs_sb_t *sbp)
                 ((sbp)->sb_versionnum & XFS_SB_VERSION_SECTORBIT);
 }
 
+static inline int xfs_sb_version_hasasciici(xfs_sb_t *sbp)
+{
+        return (XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_4) && \
+                (sbp->sb_versionnum & XFS_SB_VERSION_BORGBIT);
+}
+
 static inline int xfs_sb_version_hasmorebits(xfs_sb_t *sbp)
 {
         return (XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_4) && \