xnu-4570.41.2.tar.gz

[apple/xnu.git] / bsd / vfs / vfs_cache.c

diff --git a/bsd/vfs/vfs_cache.c b/bsd/vfs/vfs_cache.c
index 47cf243bad4f94234003d820ea10e65b4099c212..b24dbc590153dbd9ddde5f37451d24b9b171f70a 100644 (file)
--- a/bsd/vfs/vfs_cache.c
+++ b/bsd/vfs/vfs_cache.c
@@ -388,12 +388,12 @@ vnode_issubdir(vnode_t vp, vnode_t dvp, int *is_subdir, vfs_context_t ctx)
 }
 
 /*
- * This function builds the path to a filename in "buff".  The
- * length of the buffer *INCLUDING* the trailing zero byte is
- * returned in outlen.  NOTE: the length includes the trailing
- * zero byte and thus the length is one greater than what strlen
- * would return.  This is important and lots of code elsewhere
- * in the kernel assumes this behavior.
+ * This function builds the path in "buff" from the supplied vnode.
+ * The length of the buffer *INCLUDING* the trailing zero byte is
+ * returned in outlen.  NOTE: the length includes the trailing zero
+ * byte and thus the length is one greater than what strlen would
+ * return.  This is important and lots of code elsewhere in the kernel
+ * assumes this behavior.
  * 
  * This function can call vnop in file system if the parent vnode 
  * does not exist or when called for hardlinks via volfs path.  
@@ -410,9 +410,19 @@ vnode_issubdir(vnode_t vp, vnode_t dvp, int *is_subdir, vfs_context_t ctx)
  * cross over mount points during building the path. 
  *
  * passed in vp must have a valid io_count reference
+ *
+ * If parent vnode is non-NULL it also must have an io count.  This
+ * allows build_path_with_parent to be safely called for operations
+ * unlink, rmdir and rename that already have io counts on the target
+ * and the directory. In this way build_path_with_parent does not have
+ * to try and obtain an additional io count on the parent.  Taking an
+ * io count ont the parent can lead to dead lock if a forced unmount
+ * occures at the right moment. For a fuller explaination on how this
+ * can occur see the comment for vn_getpath_with_parent.
+ *
  */
 int
-build_path(vnode_t first_vp, char *buff, int buflen, int *outlen, int flags, vfs_context_t ctx)
+build_path_with_parent(vnode_t first_vp, vnode_t parent_vp, char *buff, int buflen, int *outlen, int flags, vfs_context_t ctx)
 {
         vnode_t vp, tvp;
        vnode_t vp_with_iocount;
@@ -587,7 +597,7 @@ again:
 
                        NAME_CACHE_UNLOCK();
 
-                       if (vp != first_vp && vp != vp_with_iocount) {
+                       if (vp != first_vp && vp != parent_vp && vp != vp_with_iocount) {
                                if (vp_with_iocount) {
                                        vnode_put(vp_with_iocount);
                                        vp_with_iocount = NULLVP;
@@ -678,7 +688,7 @@ bad_news:
 
                        NAME_CACHE_UNLOCK();
 
-                       if (vp != first_vp && vp != vp_with_iocount) {
+                       if (vp != first_vp && vp != parent_vp && vp != vp_with_iocount) {
                                if (vp_with_iocount) {
                                        vnode_put(vp_with_iocount);
                                        vp_with_iocount = NULLVP;
@@ -745,6 +755,11 @@ out:
        return (ret);
 }
 
+int
+build_path(vnode_t first_vp, char *buff, int buflen, int *outlen, int flags, vfs_context_t ctx)
+{
+       return (build_path_with_parent(first_vp, NULL, buff, buflen, outlen, flags, ctx));
+}
 
 /*
  * return NULLVP if vp's parent doesn't
@@ -1362,7 +1377,7 @@ skiprsrcfork:
 
 #if CONFIG_MACF
 
-               /* 
+               /*
                 * Name cache provides authorization caching (see below)
                 * that will short circuit MAC checks in lookup().
                 * We must perform MAC check here.  On denial
@@ -1685,7 +1700,7 @@ cache_lookup_locked(vnode_t dvp, struct componentname *cnp)
        ncpp = NCHHASH(dvp, cnp->cn_hash);
        LIST_FOREACH(ncp, ncpp, nc_hash) {
                if ((ncp->nc_dvp == dvp) && (ncp->nc_hashval == hashval)) {
-                       if (memcmp(ncp->nc_name, cnp->cn_nameptr, namelen) == 0 && ncp->nc_name[namelen] == 0)
+                       if (strncmp(ncp->nc_name, cnp->cn_nameptr, namelen) == 0 && ncp->nc_name[namelen] == 0)
                                break;
                }
        }
@@ -1772,7 +1787,7 @@ relook:
        ncpp = NCHHASH(dvp, cnp->cn_hash);
        LIST_FOREACH(ncp, ncpp, nc_hash) {
                if ((ncp->nc_dvp == dvp) && (ncp->nc_hashval == hashval)) {
-                       if (memcmp(ncp->nc_name, cnp->cn_nameptr, namelen) == 0 && ncp->nc_name[namelen] == 0)
+                       if (strncmp(ncp->nc_name, cnp->cn_nameptr, namelen) == 0 && ncp->nc_name[namelen] == 0)
                                break;
                }
        }
@@ -2211,7 +2226,7 @@ resize_namecache(u_int newsize)
 }
 
 static void
-cache_delete(struct namecache *ncp, int age_entry)
+cache_delete(struct namecache *ncp, int free_entry)
 {
         NCHSTAT(ncs_deletes);
 
@@ -2232,16 +2247,13 @@ cache_delete(struct namecache *ncp, int age_entry)
         */
        ncp->nc_hash.le_prev = NULL;
 
-       if (age_entry) {
-               /*
-                * make it the next one available
-                * for cache_enter's use
-                */
-               TAILQ_REMOVE(&nchead, ncp, nc_entry);
-               TAILQ_INSERT_HEAD(&nchead, ncp, nc_entry);
-       }
        vfs_removename(ncp->nc_name);
        ncp->nc_name = NULL;
+       if (free_entry) {
+               TAILQ_REMOVE(&nchead, ncp, nc_entry);
+               FREE_ZONE(ncp, sizeof(*ncp), M_CACHE);
+               numcache--;
+       }
 }
 
 
@@ -2475,7 +2487,7 @@ add_name_internal(const char *name, uint32_t len, u_int hashval, boolean_t need_
        lck_mtx_lock_spin(&strcache_mtx_locks[lock_index]);
 
        for (entry = head->lh_first; entry != NULL; chain_len++, entry = entry->hash_chain.le_next) {
-               if (memcmp(entry->str, name, len) == 0 && entry->str[len] == 0) {
+               if (strncmp(entry->str, name, len) == 0 && entry->str[len] == 0) {
                        entry->refcount++;
                        break;
                }