[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, 36 insertions, 26 deletions

diff --git a/fs/xfs/xfs_dir2_sf.c b/fs/xfs/xfs_dir2_sf.c
index ca33bc62edc2..dcd09cada43f 100644
--- a/fs/xfs/xfs_dir2_sf.c
+++ b/fs/xfs/xfs_dir2_sf.c
@@ -814,6 +814,7 @@ xfs_dir2_sf_lookup(
         int                     i;              /* entry index */
         xfs_dir2_sf_entry_t     *sfep;          /* shortform directory entry */
         xfs_dir2_sf_t           *sfp;           /* shortform structure */
+        enum xfs_dacmp          cmp;            /* comparison result */
 
         xfs_dir2_trace_args("sf_lookup", args);
         xfs_dir2_sf_check(args);
@@ -836,6 +837,7 @@ xfs_dir2_sf_lookup(
          */
         if (args->namelen == 1 && args->name[0] == '.') {
                 args->inumber = dp->i_ino;
+                args->cmpresult = XFS_CMP_EXACT;
                 return XFS_ERROR(EEXIST);
         }
         /*
@@ -844,27 +846,39 @@ xfs_dir2_sf_lookup(
         if (args->namelen == 2 &&
             args->name[0] == '.' && args->name[1] == '.') {
                 args->inumber = xfs_dir2_sf_get_inumber(sfp, &sfp->hdr.parent);
+                args->cmpresult = XFS_CMP_EXACT;
                 return XFS_ERROR(EEXIST);
         }
         /*
          * Loop over all the entries trying to match ours.
          */
-        for (i = 0, sfep = xfs_dir2_sf_firstentry(sfp);
-             i < sfp->hdr.count;
-             i++, sfep = xfs_dir2_sf_nextentry(sfp, sfep)) {
-                if (sfep->namelen == args->namelen &&
-                    sfep->name[0] == args->name[0] &&
-                    memcmp(args->name, sfep->name, args->namelen) == 0) {
-                        args->inumber =
-                                xfs_dir2_sf_get_inumber(sfp,
-                                        xfs_dir2_sf_inumberp(sfep));
-                        return XFS_ERROR(EEXIST);
+        for (i = 0, sfep = xfs_dir2_sf_firstentry(sfp); i < sfp->hdr.count;
+                                i++, sfep = xfs_dir2_sf_nextentry(sfp, sfep)) {
+                /*
+                 * Compare name and if it's an exact match, return the inode
+                 * number. If it's the first case-insensitive match, store the
+                 * inode number and continue looking for an exact match.
+                 */
+                cmp = dp->i_mount->m_dirnameops->compname(args, sfep->name,
+                                                                sfep->namelen);
+                if (cmp != XFS_CMP_DIFFERENT && cmp != args->cmpresult) {
+                        args->cmpresult = cmp;
+                        args->inumber = xfs_dir2_sf_get_inumber(sfp,
+                                                xfs_dir2_sf_inumberp(sfep));
+                        if (cmp == XFS_CMP_EXACT)
+                                return XFS_ERROR(EEXIST);
                 }
         }
+        ASSERT(args->oknoent);
+        /*
+         * Here, we can only be doing a lookup (not a rename or replace).
+         * If a case-insensitive match was found earlier, return "found".
+         */
+        if (args->cmpresult == XFS_CMP_CASE)
+                return XFS_ERROR(EEXIST);
         /*
          * Didn't find it.
          */
-        ASSERT(args->oknoent);
         return XFS_ERROR(ENOENT);
 }
 
@@ -904,24 +918,21 @@ xfs_dir2_sf_removename(
          * Loop over the old directory entries.
          * Find the one we're deleting.
          */
-        for (i = 0, sfep = xfs_dir2_sf_firstentry(sfp);
-             i < sfp->hdr.count;
-             i++, sfep = xfs_dir2_sf_nextentry(sfp, sfep)) {
-                if (sfep->namelen == args->namelen &&
-                    sfep->name[0] == args->name[0] &&
-                    memcmp(sfep->name, args->name, args->namelen) == 0) {
+        for (i = 0, sfep = xfs_dir2_sf_firstentry(sfp); i < sfp->hdr.count;
+                                i++, sfep = xfs_dir2_sf_nextentry(sfp, sfep)) {
+                if (xfs_da_compname(args, sfep->name, sfep->namelen) ==
+                                                                XFS_CMP_EXACT) {
                         ASSERT(xfs_dir2_sf_get_inumber(sfp,
-                                        xfs_dir2_sf_inumberp(sfep)) ==
-                                args->inumber);
+                                                xfs_dir2_sf_inumberp(sfep)) ==
+                                                                args->inumber);
                         break;
                 }
         }
         /*
          * Didn't find it.
          */
-        if (i == sfp->hdr.count) {
+        if (i == sfp->hdr.count)
                 return XFS_ERROR(ENOENT);
-        }
         /*
          * Calculate sizes.
          */
@@ -1042,11 +1053,10 @@ xfs_dir2_sf_replace(
          */
         else {
                 for (i = 0, sfep = xfs_dir2_sf_firstentry(sfp);
-                     i < sfp->hdr.count;
-                     i++, sfep = xfs_dir2_sf_nextentry(sfp, sfep)) {
-                        if (sfep->namelen == args->namelen &&
-                            sfep->name[0] == args->name[0] &&
-                            memcmp(args->name, sfep->name, args->namelen) == 0) {
+                                i < sfp->hdr.count;
+                                i++, sfep = xfs_dir2_sf_nextentry(sfp, sfep)) {
+                        if (xfs_da_compname(args, sfep->name, sfep->namelen) ==
+                                                                XFS_CMP_EXACT) {
 #if XFS_BIG_INUMS || defined(DEBUG)
                                 ino = xfs_dir2_sf_get_inumber(sfp,
                                         xfs_dir2_sf_inumberp(sfep));