[XFS] Name operation vector for hash and compare

Adds two pieces of functionality for the basis of case-insensitive support
in XFS:

1. A comparison result enumerated type: xfs_dacmp. It represents an

exact match, case-insensitive match or no match at all. This patch

only implements different and exact results.

2. xfs_nameops vector for specifying how to perform the hash generation

of filenames and comparision methods. In this patch the hash vector

points to the existing xfs_da_hashname function and the comparison

method does a length compare, and if the same, does a memcmp and

return the xfs_dacmp result.

All filename functions that use the hash (create, lookup remove, rename,
etc) now use the xfs_nameops.hashname function and all directory lookup
functions also use the xfs_nameops.compname function.

The lookup functions also handle case-insensitive results even though the
default comparison function cannot return that. And important aspect of
the lookup functions is that an exact match always has precedence over a
case-insensitive. So while a case-insensitive match is found, we have to
keep looking just in case there is an exact match. In the meantime, the
info for the first case-insensitive match is retained if no exact match is
found.

SGI-PV: 981519
SGI-Modid: xfs-linux-melb:xfs-kern:31205a

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

1 files changed, 22 insertions, 0 deletions

diff --git a/fs/xfs/xfs_da_btree.h b/fs/xfs/xfs_da_btree.h
index 7facf86f74f9..e64c6924996f 100644
--- a/fs/xfs/xfs_da_btree.h
+++ b/fs/xfs/xfs_da_btree.h
@@ -99,6 +99,15 @@ typedef struct xfs_da_node_entry xfs_da_node_entry_t;
  *========================================================================*/
 
 /*
+ * Search comparison results
+ */
+enum xfs_dacmp {
+        XFS_CMP_DIFFERENT,      /* names are completely different */
+        XFS_CMP_EXACT,          /* names are exactly the same */
+        XFS_CMP_CASE            /* names are same but differ in case */
+};
+
+/*
  * Structure to ease passing around component names.
  */
 typedef struct xfs_da_args {
@@ -127,6 +136,7 @@ typedef struct xfs_da_args {
         unsigned char   rename;         /* T/F: this is an atomic rename op */
         unsigned char   addname;        /* T/F: this is an add operation */
         unsigned char   oknoent;        /* T/F: ok to return ENOENT, else die */
+        enum xfs_dacmp  cmpresult;      /* name compare result for lookups */
 } xfs_da_args_t;
 
 /*
@@ -201,6 +211,14 @@ typedef struct xfs_da_state {
                 (uint)(XFS_DA_LOGOFF(BASE, ADDR)), \
                 (uint)(XFS_DA_LOGOFF(BASE, ADDR)+(SIZE)-1)
 
+/*
+ * Name ops for directory and/or attr name operations
+ */
+struct xfs_nameops {
+        xfs_dahash_t    (*hashname)(struct xfs_name *);
+        enum xfs_dacmp  (*compname)(struct xfs_da_args *, const char *, int);
+};
+
 
 #ifdef __KERNEL__
 /*========================================================================
@@ -249,6 +267,10 @@ int	xfs_da_shrink_inode(xfs_da_args_t *args, xfs_dablk_t dead_blkno,
                                           xfs_dabuf_t *dead_buf);
 
 uint xfs_da_hashname(const uchar_t *name_string, int name_length);
+enum xfs_dacmp xfs_da_compname(struct xfs_da_args *args,
+                                const char *name, int len);
+
+
 xfs_da_state_t *xfs_da_state_alloc(void);
 void xfs_da_state_free(xfs_da_state_t *state);