[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, 14 insertions, 9 deletions

diff --git a/fs/xfs/xfs_dir2_node.c b/fs/xfs/xfs_dir2_node.c
index e29b7c63e198..fedf8f976a10 100644
--- a/fs/xfs/xfs_dir2_node.c
+++ b/fs/xfs/xfs_dir2_node.c
@@ -556,6 +556,7 @@ xfs_dir2_leafn_lookup_for_entry(
         xfs_mount_t             *mp;            /* filesystem mount point */
         xfs_dir2_db_t           newdb;          /* new data block number */
         xfs_trans_t             *tp;            /* transaction pointer */
+        enum xfs_dacmp          cmp;            /* comparison result */
 
         dp = args->dp;
         tp = args->trans;
@@ -620,17 +621,21 @@ xfs_dir2_leafn_lookup_for_entry(
                 dep = (xfs_dir2_data_entry_t *)((char *)curbp->data +
                         xfs_dir2_dataptr_to_off(mp, be32_to_cpu(lep->address)));
                 /*
-                 * Compare the entry, return it if it matches.
+                 * Compare the entry and if it's an exact match, return
+                 * EEXIST immediately. If it's the first case-insensitive
+                 * match, store the inode number and continue looking.
                  */
-                if (dep->namelen == args->namelen && memcmp(dep->name,
-                                        args->name, args->namelen) == 0) {
+                cmp = mp->m_dirnameops->compname(args, dep->name, dep->namelen);
+                if (cmp != XFS_CMP_DIFFERENT && cmp != args->cmpresult) {
+                        args->cmpresult = cmp;
                         args->inumber = be64_to_cpu(dep->inumber);
                         di = (int)((char *)dep - (char *)curbp->data);
                         error = EEXIST;
-                        goto out;
+                        if (cmp == XFS_CMP_EXACT)
+                                goto out;
                 }
         }
-        /* Didn't find a match. */
+        /* Didn't find an exact match. */
         error = ENOENT;
         di = -1;
         ASSERT(index == be16_to_cpu(leaf->hdr.count) || args->oknoent);
@@ -1813,6 +1818,8 @@ xfs_dir2_node_lookup(
         error = xfs_da_node_lookup_int(state, &rval);
         if (error)
                 rval = error;
+        else if (rval == ENOENT && args->cmpresult == XFS_CMP_CASE)
+                rval = EEXIST;  /* a case-insensitive match was found */
         /*
          * Release the btree blocks and leaf block.
          */
@@ -1856,9 +1863,8 @@ xfs_dir2_node_removename(
          * Look up the entry we're deleting, set up the cursor.
          */
         error = xfs_da_node_lookup_int(state, &rval);
-        if (error) {
+        if (error)
                 rval = error;
-        }
         /*
          * Didn't find it, upper layer screwed up.
          */
@@ -1875,9 +1881,8 @@ xfs_dir2_node_removename(
          */
         error = xfs_dir2_leafn_remove(args, blk->bp, blk->index,
                 &state->extrablk, &rval);
-        if (error) {
+        if (error)
                 return error;
-        }
         /*
          * Fix the hash values up the btree.
          */