X-Git-Url: https://git.saurik.com/apple/xnu.git/blobdiff_plain/6d2010ae8f7a6078e10b361c6962983bab233e0f..143464d58d2bd6378e74eec636961ceb0d32fb91:/bsd/hfs/hfs_chash.c

diff --git a/bsd/hfs/hfs_chash.c b/bsd/hfs/hfs_chash.c
index 997d247ae..b162a53b2 100644
--- a/bsd/hfs/hfs_chash.c
+++ b/bsd/hfs/hfs_chash.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002-2008 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 2002-2012 Apple Inc. All rights reserved.
  *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  * 
@@ -108,11 +108,7 @@ static void hfs_chash_lock_spin(struct hfsmount *hfsmp)
 	lck_mtx_lock_spin(&hfsmp->hfs_chash_mutex);
 }
 
-#ifdef i386
-static void hfs_chash_lock_convert (struct hfsmount *hfsmp)
-#else
 static void hfs_chash_lock_convert (__unused struct hfsmount *hfsmp)
-#endif
 {
 	lck_mtx_convert_spin(&hfsmp->hfs_chash_mutex);
 }
@@ -188,7 +184,7 @@ loop:
 			 */
 		        return (NULL);
 		}
-		if (!skiplock && hfs_lock(cp, HFS_EXCLUSIVE_LOCK) != 0) {
+		if (!skiplock && hfs_lock(cp, HFS_EXCLUSIVE_LOCK, HFS_LOCK_DEFAULT) != 0) {
 			vnode_put(vp);
 			return (NULL);
 		}
@@ -202,12 +198,12 @@ loop:
 		 */
 		if (!allow_deleted) {
 			if (cp->c_flag & (C_NOEXISTS | C_DELETED)) {
-				if (!skiplock)
-						hfs_unlock(cp);
+				if (!skiplock) {
+					hfs_unlock(cp);
+				}
 				vnode_put(vp);
-	
 				return (NULL);
-			}
+			}			
 		}
 		return (vp);
 	}
@@ -226,7 +222,7 @@ exit:
  * 
  */
 int
-hfs_chash_snoop(struct hfsmount *hfsmp, ino_t inum, int (*callout)(const struct cat_desc *,
+hfs_chash_snoop(struct hfsmount *hfsmp, ino_t inum, int existence_only, int (*callout)(const struct cat_desc *,
                 const struct cat_attr *, void *), void * arg)
 {
 	struct cnode *cp;
@@ -242,7 +238,27 @@ hfs_chash_snoop(struct hfsmount *hfsmp, ino_t inum, int (*callout)(const struct
 	for (cp = CNODEHASH(hfsmp, inum)->lh_first; cp; cp = cp->c_hash.le_next) {
 		if (cp->c_fileid != inum)
 			continue;
-	       /* Skip cnodes that have been removed from the catalog */
+	
+		/*
+		 * Under normal circumstances, we would want to return ENOENT if a cnode is in
+		 * the hash and it is marked C_NOEXISTS or C_DELETED.  However, if the CNID
+		 * namespace has wrapped around, then we have the possibility of collisions.  
+		 * In that case, we may use this function to validate whether or not we 
+		 * should trust the nextCNID value in the hfs mount point.  
+		 * 
+		 * If we didn't do this, then it would be possible for a cnode that is no longer backed
+		 * by anything on-disk (C_NOEXISTS) to still exist in the hash along with its
+		 * vnode.  The cat_create routine could then create a new entry in the catalog
+		 * re-using that CNID.  Then subsequent hfs_getnewvnode calls will repeatedly fail
+		 * trying to look it up/validate it because it is marked C_NOEXISTS.  So we want
+		 * to prevent that from happening as much as possible.
+		 */
+		if (existence_only) {
+			result = 0;
+			break;
+		}
+
+		/* Skip cnodes that have been removed from the catalog */
 		if (cp->c_flag & (C_NOEXISTS | C_DELETED)) {
 			break;
 		}
@@ -322,17 +338,17 @@ loop_with_lock:
 		        	goto loop;
 		}
 		if (ncp) {
-		        /*
+			/*
 			 * someone else won the race to create
 			 * this cnode and add it to the hash
 			 * just dump our allocation
 			 */
-		    FREE_ZONE(ncp, sizeof(struct cnode), M_HFSNODE);
+			FREE_ZONE(ncp, sizeof(struct cnode), M_HFSNODE);
 			ncp = NULL;
 		}
 
 		if (!skiplock) {
-			hfs_lock(cp, HFS_FORCE_LOCK);
+			hfs_lock(cp, HFS_EXCLUSIVE_LOCK, HFS_LOCK_ALLOW_NOEXISTS);
 		}
 
 		/*
@@ -356,9 +372,8 @@ loop_with_lock:
 				vnode_put(vp);
 			} else {
 				hfs_chash_lock_spin(hfsmp);
-		        CLR(cp->c_hflag, H_ATTACH);
+				CLR(cp->c_hflag, H_ATTACH);
 				*hflags &= ~H_ATTACH;
-
 				if (ISSET(cp->c_hflag, H_WAITING)) {
 					CLR(cp->c_hflag, H_WAITING);
 					wakeup((caddr_t)cp);
@@ -383,7 +398,8 @@ loop_with_lock:
 
 	if (ncp == NULL) {
 		hfs_chash_unlock(hfsmp);
-	    MALLOC_ZONE(ncp, struct cnode *, sizeof(struct cnode), M_HFSNODE, M_WAITOK);
+
+	        MALLOC_ZONE(ncp, struct cnode *, sizeof(struct cnode), M_HFSNODE, M_WAITOK);
 		/*
 		 * since we dropped the chash lock, 
 		 * we need to go back and re-verify
@@ -403,7 +419,7 @@ loop_with_lock:
 
 	lck_rw_init(&ncp->c_rwlock, hfs_rwlock_group, hfs_lock_attr);
 	if (!skiplock)
-		(void) hfs_lock(ncp, HFS_EXCLUSIVE_LOCK);
+		(void) hfs_lock(ncp, HFS_EXCLUSIVE_LOCK, HFS_LOCK_DEFAULT);
 
 	/* Insert the new cnode with it's H_ALLOC flag set */
 	LIST_INSERT_HEAD(CNODEHASH(hfsmp, inum), ncp, c_hash);