[src/trunk]: src/sys Extend generic dirhash to include an empty directory che...

[reinoud <reinoud%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/00443f2871e8
branches:  trunk
changeset: 787840:00443f2871e8
user:      reinoud <reinoud%NetBSD.org@localhost>
date:      Sun Jul 07 19:31:26 2013 +0000

description:
Extend generic dirhash to include an empty directory checker based on
the knowledge the dirhash has. This is done by keeping a count of the current
hash entries.

diffstat:

 sys/kern/vfs_dirhash.c |  38 ++++++++++++++++++++++++++++++++++++--
 sys/sys/dirhash.h      |   4 +++-
 2 files changed, 39 insertions(+), 3 deletions(-)

diffs (101 lines):

diff -r 458936933302 -r 00443f2871e8 sys/kern/vfs_dirhash.c
--- a/sys/kern/vfs_dirhash.c    Sun Jul 07 10:52:52 2013 +0000
+++ b/sys/kern/vfs_dirhash.c    Sun Jul 07 19:31:26 2013 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: vfs_dirhash.c,v 1.10 2009/02/06 23:56:26 enami Exp $ */
+/* $NetBSD: vfs_dirhash.c,v 1.11 2013/07/07 19:31:26 reinoud Exp $ */
 
 /*
  * Copyright (c) 2008 Reinoud Zandijk
@@ -28,7 +28,7 @@
 
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_dirhash.c,v 1.10 2009/02/06 23:56:26 enami Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_dirhash.c,v 1.11 2013/07/07 19:31:26 reinoud Exp $");
 
 /* CLEAN UP! */
 #include <sys/param.h>
@@ -165,6 +165,7 @@
 
        dirh->flags &= ~DIRH_COMPLETE;
        dirh->flags |=  DIRH_PURGED;
+       dirh->num_files = 0;
 
        dirhashsize -= dirh->size;
        dirh->size = 0;
@@ -309,6 +310,7 @@
        dirh_e->entry_size  = entry_size;
 
        dirh->size  += sizeof(struct dirhash_entry);
+       dirh->num_files++;
        dirhashsize += sizeof(struct dirhash_entry);
        LIST_INSERT_HEAD(&dirh->entries[hashline], dirh_e, next);
 }
@@ -378,6 +380,8 @@
                KASSERT(dirh_e->entry_size == entry_size);
                LIST_REMOVE(dirh_e, next);
                dirh->size -= sizeof(struct dirhash_entry);
+               KASSERT(dirh->num_files > 0);
+               dirh->num_files--;
                dirhashsize -= sizeof(struct dirhash_entry);
 
                dirhash_enter_freed(dirh, offset, entry_size);
@@ -469,3 +473,33 @@
        *result = NULL;
        return 0;
 }
+
+
+bool
+dirhash_dir_isempty(struct dirhash *dirh)
+{
+#ifdef DEBUG
+       struct dirhash_entry *dirh_e;
+       int hashline, num;
+
+       num = 0;
+       for (hashline = 0; hashline < DIRHASH_HASHSIZE; hashline++) {
+               LIST_FOREACH(dirh_e, &dirh->entries[hashline], next) {
+                       num++;
+               }
+       }
+
+       if (dirh->num_files != num) {
+               printf("dirhash_dir_isempy: dirhash_counter failed: "
+                       "dirh->num_files = %d, counted %d\n",
+                       dirh->num_files, num);
+               assert(dirh->num_files == num);
+       }
+#endif
+       /* assert the directory hash info is valid */
+       KASSERT(dirh->flags & DIRH_COMPLETE);
+
+       /* the directory is empty when only '..' lifes in it or is absent */
+       return (dirh->num_files <= 1);
+}
+
diff -r 458936933302 -r 00443f2871e8 sys/sys/dirhash.h
--- a/sys/sys/dirhash.h Sun Jul 07 10:52:52 2013 +0000
+++ b/sys/sys/dirhash.h Sun Jul 07 19:31:26 2013 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: dirhash.h,v 1.5 2009/09/27 21:50:48 reinoud Exp $ */
+/* $NetBSD: dirhash.h,v 1.6 2013/07/07 19:31:26 reinoud Exp $ */
 
 /*
  * Copyright (c) 2008 Reinoud Zandijk
@@ -52,6 +52,7 @@
        uint32_t                 flags;
        uint32_t                 size;                  /* in bytes */
        uint32_t                 refcnt;
+       uint32_t                 num_files;
        LIST_HEAD(, dirhash_entry) entries[DIRHASH_HASHSIZE];
        LIST_HEAD(, dirhash_entry) free_entries;
        TAILQ_ENTRY(dirhash) next;
@@ -79,5 +80,6 @@
            struct dirhash_entry **);
 int    dirhash_lookup_freed(struct dirhash *, uint32_t,
            struct dirhash_entry **);
+bool   dirhash_dir_isempty(struct dirhash *dirh);
 
 #endif /* _SYS_DIRHASH_H_ */