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[PATCH 3/4] XFS: ASCII case-insensitive support

To: xfs@xxxxxxxxxxx
Subject: [PATCH 3/4] XFS: ASCII case-insensitive support
From: Barry Naujok <bnaujok@xxxxxxx>
Date: Mon, 21 Apr 2008 18:31:06 +1000
Cc: linux-fsdevel@xxxxxxxxxxxxxxx
References: <20080421083103.433280025@xxxxxxxxxxxxxxxxxxxxxxx>
Sender: xfs-bounce@xxxxxxxxxxx
User-agent: quilt/0.46-1
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>

Signed-off-by: Barry Naujok <bnaujok@xxxxxxx>


---
 fs/xfs/linux-2.6/xfs_linux.h |    1 
 fs/xfs/linux-2.6/xfs_super.c |    7 ++++-
 fs/xfs/xfs_dir2.c            |   53 ++++++++++++++++++++++++++++++++++++++++++-
 fs/xfs/xfs_fs.h              |    1 
 fs/xfs/xfs_fsops.c           |    4 ++-
 fs/xfs/xfs_sb.h              |   10 +++++++-
 6 files changed, 72 insertions(+), 4 deletions(-)

Index: kern_ci/fs/xfs/linux-2.6/xfs_linux.h
===================================================================
--- kern_ci.orig/fs/xfs/linux-2.6/xfs_linux.h
+++ kern_ci/fs/xfs/linux-2.6/xfs_linux.h
@@ -75,6 +75,7 @@
 #include <linux/delay.h>
 #include <linux/log2.h>
 #include <linux/spinlock.h>
+#include <linux/ctype.h>
 
 #include <asm/page.h>
 #include <asm/div64.h>
Index: kern_ci/fs/xfs/linux-2.6/xfs_super.c
===================================================================
--- kern_ci.orig/fs/xfs/linux-2.6/xfs_super.c
+++ kern_ci/fs/xfs/linux-2.6/xfs_super.c
@@ -67,6 +67,8 @@ static kmem_zone_t *xfs_vnode_zone;
 static kmem_zone_t *xfs_ioend_zone;
 mempool_t *xfs_ioend_pool;
 
+extern struct dentry_operations xfs_ci_dentry_operations;
+
 STATIC struct xfs_mount_args *
 xfs_args_allocate(
        struct super_block      *sb,
@@ -564,7 +566,10 @@ xfs_set_inodeops(
                inode->i_mapping->a_ops = &xfs_address_space_operations;
                break;
        case S_IFDIR:
-               inode->i_op = &xfs_dir_inode_operations;
+               if (xfs_sb_version_hasoldci(&XFS_M(inode->i_sb)->m_sb))
+                       inode->i_op = &xfs_dir_ci_inode_operations;
+               else
+                       inode->i_op = &xfs_dir_inode_operations;
                inode->i_fop = &xfs_dir_file_operations;
                break;
        case S_IFLNK:
Index: kern_ci/fs/xfs/xfs_dir2.c
===================================================================
--- kern_ci.orig/fs/xfs/xfs_dir2.c
+++ kern_ci/fs/xfs/xfs_dir2.c
@@ -50,6 +50,54 @@ kmem_zone_t  *xfs_name_zone;
 
 extern const struct xfs_nameops xfs_default_nameops;
 
+/*
+ * V1/OLDCI case-insensitive support for directories that was used in IRIX.
+ *
+ * This is ASCII only case support, ie. A-Z.
+ */
+STATIC xfs_dahash_t
+xfs_ascii_ci_hashname(
+       struct xfs_name *name)
+{
+       xfs_dahash_t    hash;
+       int             i;
+
+       for (i = 0, hash = 0; i < name->len; i++)
+               hash = tolower(name->name[i]) ^ rol32(hash, 7);
+
+       return hash;
+}
+
+STATIC xfs_dacmp_t
+xfs_ascii_ci_compname(
+       const char      *name1,
+       int             len1,
+       const char      *name2,
+       int             len2)
+{
+       xfs_dacmp_t     result;
+       int             i;
+
+       if (len1 != len2)
+               return XFS_CMP_DIFFERENT;
+
+       result = XFS_CMP_EXACT;
+       for (i = 0; i < len1; i++) {
+               if (name1[i] == name2[i])
+                       continue;
+               if (tolower(name1[i]) != tolower(name2[i]))
+                       return XFS_CMP_DIFFERENT;
+               result = XFS_CMP_CASE;
+       }
+
+       return result;
+}
+
+static struct xfs_nameops xfs_ascii_ci_nameops = {
+       .hashname       = xfs_ascii_ci_hashname,
+       .compname       = xfs_ascii_ci_compname,
+};
+
 void
 xfs_dir_mount(
        xfs_mount_t     *mp)
@@ -69,7 +117,10 @@ xfs_dir_mount(
                (mp->m_dirblksize - (uint)sizeof(xfs_da_node_hdr_t)) /
                (uint)sizeof(xfs_da_node_entry_t);
        mp->m_dir_magicpct = (mp->m_dirblksize * 37) / 100;
-       mp->m_dirnameops = &xfs_default_nameops;
+       if (xfs_sb_version_hasoldci(&mp->m_sb))
+               mp->m_dirnameops = &xfs_ascii_ci_nameops;
+       else
+               mp->m_dirnameops = &xfs_default_nameops;
 }
 
 /*
Index: kern_ci/fs/xfs/xfs_fs.h
===================================================================
--- kern_ci.orig/fs/xfs/xfs_fs.h
+++ kern_ci/fs/xfs/xfs_fs.h
@@ -239,6 +239,7 @@ typedef struct xfs_fsop_resblks {
 #define XFS_FSOP_GEOM_FLAGS_LOGV2      0x0100  /* log format version 2 */
 #define XFS_FSOP_GEOM_FLAGS_SECTOR     0x0200  /* sector sizes >1BB    */
 #define XFS_FSOP_GEOM_FLAGS_ATTR2      0x0400  /* inline attributes rework */
+#define XFS_FSOP_GEOM_FLAGS_DIRV2CI    0x1000  /* ASCII only CI names */
 #define XFS_FSOP_GEOM_FLAGS_LAZYSB     0x4000  /* lazy superblock counters */
 
 
Index: kern_ci/fs/xfs/xfs_fsops.c
===================================================================
--- kern_ci.orig/fs/xfs/xfs_fsops.c
+++ kern_ci/fs/xfs/xfs_fsops.c
@@ -95,6 +95,8 @@ xfs_fs_geometry(
                                XFS_FSOP_GEOM_FLAGS_DIRV2 : 0) |
                        (xfs_sb_version_hassector(&mp->m_sb) ?
                                XFS_FSOP_GEOM_FLAGS_SECTOR : 0) |
+                       (xfs_sb_version_hasoldci(&mp->m_sb) ?
+                               XFS_FSOP_GEOM_FLAGS_DIRV2CI : 0) |
                        (xfs_sb_version_haslazysbcount(&mp->m_sb) ?
                                XFS_FSOP_GEOM_FLAGS_LAZYSB : 0) |
                        (xfs_sb_version_hasattr2(&mp->m_sb) ?
@@ -629,7 +631,7 @@ xfs_fs_goingdown(
                        xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT);
                        thaw_bdev(sb->s_bdev, sb);
                }
-       
+
                break;
        }
        case XFS_FSOP_GOING_FLAGS_LOGFLUSH:
Index: kern_ci/fs/xfs/xfs_sb.h
===================================================================
--- kern_ci.orig/fs/xfs/xfs_sb.h
+++ kern_ci/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_hassect
                ((sbp)->sb_versionnum & XFS_SB_VERSION_SECTORBIT);
 }
 
+static inline int xfs_sb_version_hasoldci(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) && \

-- 


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