catalog.c

ARM 嵌入式 系统 设计与实例开发 实验教材 二源码

		   if (hfs_bfind(&brec, mdb->cat_tree,
				 HFS_BKEY(key), HFS_BFIND_READ_EQ)) {
		        /* uh oh. we failed to read the record.
			 * the entry doesn't actually exist. */
		        goto read_fail;
		   }

		   read_entry(entry, &brec);
		   
		   /* error */
		   if (!entry->cnid) {
		        goto read_fail;
		   }

		   /* we don't have to acquire a spinlock here or
		    * below for the unlocking bits as we're the first
		    * user of this entry. */
		   entry->state &= ~HFS_LOCK;
		   hfs_wake_up(&entry->wait);
		}

		return entry;
	}


	/* try to allocate more entries. grow_entries() doesn't release
	 * the spinlock. */
	if (grow_entries())
	        goto add_new_entry;

	spin_unlock(&entry_lock);
	return NULL;

read_fail: 
	/* short-cut hfs_cat_put by doing everything here. */
	spin_lock(&entry_lock);
	list_del(&entry->hash);
	list_del(&entry->list);
	init_entry(entry);
	list_add(&entry->list, &entry_unused);
	entries_stat.nr_free_entries++;
	spin_unlock(&entry_lock);
	return NULL;
}

/*
 * get_entry()
 *
 * Try to return an entry for the indicated file or directory.
 * If ('read' == 0) then no attempt will be made to read it from disk
 * and a locked, but uninitialized, entry is returned.
 */
static struct hfs_cat_entry *get_entry(struct hfs_mdb *mdb,
				       const struct hfs_cat_key *key,
				       const int read)
{
	struct hfs_cat_entry * entry;

#if defined(DEBUG_CATALOG) || defined(DEBUG_ALL)
	hfs_warn("hfs_get_entry: mdb=%p key=%s read=%d\n",
		 mdb, key->CName.Name, read);
#endif

	spin_lock(&entry_lock);
	entry = find_entry(mdb, key);
	if (!entry) {
	        return get_new_entry(mdb, key, read);
	}
	spin_unlock(&entry_lock);
	wait_on_entry(entry);
	return entry;
}

/* 
 * new_cnid()
 *
 * Allocate a CNID to use for a new file or directory.
 */
static inline hfs_u32 new_cnid(struct hfs_mdb *mdb)
{
	/* If the create succeeds then the mdb will get dirtied */
	return htonl(mdb->next_id++);
}

/*
 * update_dir()
 *
 * Update counts, times and dirt on a changed directory
 */
static void update_dir(struct hfs_mdb *mdb, struct hfs_cat_entry *dir,
		       int is_dir, int count)
{
	/* update counts */
	if (is_dir) {
		mdb->dir_count += count;
		dir->u.dir.dirs += count;
		if (dir->cnid == htonl(HFS_ROOT_CNID)) {
			mdb->root_dirs += count;
		}
	} else {
		mdb->file_count += count;
		dir->u.dir.files += count;
		if (dir->cnid == htonl(HFS_ROOT_CNID)) {
			mdb->root_files += count;
		}
	}
	
	/* update times and dirt */
	dir->modify_date = hfs_time();
	hfs_cat_mark_dirty(dir);
}

/*
 * Add a writer to dir, excluding readers.
 *
 * XXX: this is wrong. it allows a move to occur when a directory
 *      is being written to. 
 */
static inline void start_write(struct hfs_cat_entry *dir)
{
	if (dir->u.dir.readers || waitqueue_active(&dir->u.dir.read_wait)) {
		hfs_sleep_on(&dir->u.dir.write_wait);
	}
	++dir->u.dir.writers;
}

/*
 * Add a reader to dir, excluding writers.
 */
static inline void start_read(struct hfs_cat_entry *dir)
{
	if (dir->u.dir.writers || waitqueue_active(&dir->u.dir.write_wait)) {
		hfs_sleep_on(&dir->u.dir.read_wait);
	}
	++dir->u.dir.readers;
}

/*
 * Remove a writer from dir, possibly admitting readers.
 */
static inline void end_write(struct hfs_cat_entry *dir)
{
	if (!(--dir->u.dir.writers)) {
		hfs_wake_up(&dir->u.dir.read_wait);
	}
}

/*
 * Remove a reader from dir, possibly admitting writers.
 */
static inline void end_read(struct hfs_cat_entry *dir)
{
	if (!(--dir->u.dir.readers)) {
		hfs_wake_up(&dir->u.dir.write_wait);
	}
}

/*
 * create_entry()
 *
 * Add a new file or directory to the catalog B-tree and
 * return a (struct hfs_cat_entry) for it in '*result'.
 */
static int create_entry(struct hfs_cat_entry *parent, struct hfs_cat_key *key,
			const struct hfs_cat_rec *record, int is_dir,
			hfs_u32 cnid, struct hfs_cat_entry **result)
{
	struct hfs_mdb *mdb = parent->mdb;
	struct hfs_cat_entry *entry;
	struct hfs_cat_key thd_key;
	struct hfs_cat_rec thd_rec;
	int error, has_thread;

	if (result) {
		*result = NULL;
	}

	/* keep readers from getting confused by changing dir size */
	start_write(parent);

	/* create a locked entry in the cache */
	entry = get_entry(mdb, key, 0);
	if (!entry) {
		/* The entry exists but can't be read */
		error = -EIO;
		goto done;
	}

	if (entry->cnid) {
		/* The (unlocked) entry exists in the cache */
		error = -EEXIST;
		goto bail2;
	}

	/* limit directory valence to signed 16-bit integer */
        if ((parent->u.dir.dirs + parent->u.dir.files) >= HFS_MAX_VALENCE) {
		error = -ENOSPC;
		goto bail1;
	}

	has_thread = is_dir || (record->u.fil.Flags & HFS_FIL_THD);

	if (has_thread) {
		/* init some fields for the thread record */
		memset(&thd_rec, 0, sizeof(thd_rec));
		thd_rec.cdrType = is_dir ? HFS_CDR_THD : HFS_CDR_FTH;
		memcpy(&thd_rec.u.thd.ParID, &key->ParID,
		       sizeof(hfs_u32) + sizeof(struct hfs_name));

		/* insert the thread record */
		hfs_cat_build_key(cnid, NULL, &thd_key);
		error = hfs_binsert(mdb->cat_tree, HFS_BKEY(&thd_key),
				    &thd_rec, 2 + sizeof(THD_REC));
		if (error) {
			goto bail1;
		}
	}

	/* insert the record */
	error = hfs_binsert(mdb->cat_tree, HFS_BKEY(key), record,
				is_dir ?  2 + sizeof(DIR_REC) :
					  2 + sizeof(FIL_REC));
	if (error) {
		if (has_thread && (error != -EIO)) {
			/* at least TRY to remove the thread record */
			(void)hfs_bdelete(mdb->cat_tree, HFS_BKEY(&thd_key));
		}
		goto bail1;
	}

	/* update the parent directory */
	update_dir(mdb, parent, is_dir, 1);

	/* complete the cache entry and return success */
	__read_entry(entry, record);
	unlock_entry(entry);

	if (result) {
		*result = entry;
	} else {
		hfs_cat_put(entry);
	}
	goto done;

bail1:
	/* entry really didn't exist, so we don't need to really delete it.
	 * we do need to remove it from the hash, though. */
	entry->state |= HFS_DELETED;
	remove_hash(entry);
	unlock_entry(entry);
bail2:
	hfs_cat_put(entry);
done:
	end_write(parent);
	return error;
}

/*================ Global functions ================*/

/* 
 * hfs_cat_put()
 *
 * Release an entry we aren't using anymore.
 *
 * nothing in hfs_cat_put goes to sleep now except on the initial entry.  
 */
void hfs_cat_put(struct hfs_cat_entry * entry)
{
	if (entry) {
	        wait_on_entry(entry);

		/* just in case. this should never happen. */
		if (!entry->count) { 
		  hfs_warn("hfs_cat_put: trying to free free entry: %p\n",
			   entry);
		  return;
		}

#if defined(DEBUG_CATALOG) || defined(DEBUG_ALL)
		hfs_warn("hfs_cat_put: %p(%u) type=%d state=%lu\n", 
			 entry, entry->count, entry->type, entry->state);
#endif
		spin_lock(&entry_lock);
		if (!--entry->count) {
			if ((entry->state & HFS_DELETED))
			        goto entry_deleted;

			if ((entry->type == HFS_CDR_FIL)) {
		                /* clear out any cached extents */
			        if (entry->u.file.data_fork.first.next) {
				  hfs_extent_free(&entry->u.file.data_fork);
				}
				if (entry->u.file.rsrc_fork.first.next) {
				  hfs_extent_free(&entry->u.file.rsrc_fork);
				}
			}

			/* if we put a dirty entry, write it out. */
			if ((entry->state & HFS_DIRTY)) {
			        entry->state ^= HFS_DIRTY | HFS_LOCK;
				write_entry(entry);
				entry->state &= ~HFS_LOCK;
			}

			list_del(&entry->hash);
entry_deleted: 		/* deleted entries have already been removed
			 * from the hash list. */
			list_del(&entry->list);
			if (entries_stat.nr_free_entries > CCACHE_MAX) {
			        HFS_DELETE(entry);
				entries_stat.nr_entries--;
			} else {
				init_entry(entry);
				list_add(&entry->list, &entry_unused);
				entries_stat.nr_free_entries++;
			}
		}
		spin_unlock(&entry_lock);
	}
}

/* 
 * hfs_cat_get()
 *
 * Wrapper for get_entry() which always calls with ('read'==1).
 * Used for access to get_entry() from outside this file.
 */
struct hfs_cat_entry *hfs_cat_get(struct hfs_mdb *mdb,
				  const struct hfs_cat_key *key)
{
	return get_entry(mdb, key, 1);
}

/* invalidate all entries for a device */
static void invalidate_list(struct list_head *head, struct hfs_mdb *mdb,
			    struct list_head *dispose)
{
        struct list_head *next;

	next = head->next;
	for (;;) {
	        struct list_head *tmp = next;
		struct hfs_cat_entry * entry;
		
		next = next->next;
		if (tmp == head)
		        break;
		entry = list_entry(tmp, struct hfs_cat_entry, list);
		if (entry->mdb != mdb) {
			continue;
		}

		if (!entry->count) {
		        list_del(&entry->hash);
			INIT_LIST_HEAD(&entry->hash);
			list_del(&entry->list);
			list_add(&entry->list, dispose);
			continue;
		}
		
		hfs_warn("hfs_fs: entry %p(%u) busy on removed device %s.\n",
			 entry, entry->count, 
			 hfs_mdb_name(entry->mdb->sys_mdb));
	}
}

/* delete entries from a list */
static void delete_list(struct list_head *head) 
{
	struct list_head *next = head->next;
	struct hfs_cat_entry *entry;
	
	for (;;) {
		struct list_head * tmp = next;

		next = next->next;
		if (tmp == head) {
			break;
		}
		entry = list_entry(tmp, struct hfs_cat_entry, list);
		HFS_DELETE(entry);
	}
}

/* 
 * hfs_cat_invalidate()
 *
 * Called by hfs_mdb_put() to remove all the entries
 * in the cache that are associated with a given MDB.
 */
void hfs_cat_invalidate(struct hfs_mdb *mdb)
{
	LIST_HEAD(throw_away);

	spin_lock(&entry_lock);
	invalidate_list(&entry_in_use, mdb, &throw_away);
	invalidate_list(&mdb->entry_dirty, mdb, &throw_away);
	spin_unlock(&entry_lock);

	delete_list(&throw_away);
#if defined(DEBUG_CATALOG) || defined(DEBUG_ALL)
	hfs_warn("hfs_cat_invalidate: free=%d total=%d\n",
		 entries_stat.nr_free_entries,
		 entries_stat.nr_entries);
#endif
}

/*
 * hfs_cat_commit()
 *
 * Called by hfs_mdb_commit() to write dirty entries to the disk buffers.
 */
void hfs_cat_commit(struct hfs_mdb *mdb)
{
        struct list_head *tmp, *head = &mdb->entry_dirty;
	struct hfs_cat_entry *entry;

	spin_lock(&entry_lock);
	while ((tmp = head->prev) != head) {
	        entry = list_entry(tmp, struct hfs_cat_entry, list);
		  
		if ((entry->state & HFS_LOCK)) {
		        spin_unlock(&entry_lock);
			wait_on_entry(entry);
			spin_lock(&entry_lock);
		} else {
		       struct list_head *insert = &entry_in_use;

		       if (!entry->count)
			        insert = entry_in_use.prev;

		       /* add to in_use list */
		       list_del(&entry->list);
		       list_add(&entry->list, insert);

		       /* reset DIRTY, set LOCK */
		       entry->state ^= HFS_DIRTY | HFS_LOCK;
		       spin_unlock(&entry_lock);
		       write_entry(entry);
		       spin_lock(&entry_lock);
		       entry->state &= ~HFS_LOCK;
		       hfs_wake_up(&entry->wait);
		}
	}
	spin_unlock(&entry_lock);
}

/*
 * hfs_cat_free()
 *
 * Releases all the memory allocated in grow_entries().
 * Must call hfs_cat_invalidate() on all MDBs before calling this.
 * This only gets rid of the unused pool of entries. all the other
 * entry references should have either been freed by cat_invalidate
 * or moved onto the unused list.
 */
void hfs_cat_free(void)
{
	delete_list(&entry_unused);
}

/*
 * hfs_cat_compare()
 *
 * Description:
 *   This is the comparison function used for the catalog B-tree.  In
 *   comparing catalog B-tree entries, the parent id is the most
 *   significant field (compared as unsigned ints).  The name field is
 *   the least significant (compared in "Macintosh lexical order",
 *   see hfs_strcmp() in string.c)
 * Input Variable(s):
 *   struct hfs_cat_key *key1: pointer to the first key to compare
 *   struct hfs_cat_key *key2: pointer to the second key to compare
 * Output Variable(s):
 *   NONE
 * Returns:
 *   int: negative if key1<key2, positive if key1>key2, and 0 if key1==key2
 * Preconditions:
 *   key1 and key2 point to "valid" (struct hfs_cat_key)s.
 * Postconditions:
 *   This function has no side-effects
 */
int hfs_cat_compare(const struct hfs_cat_key *key1,
		    const struct hfs_cat_key *key2)
{
	unsigned int parents;
	int retval;

	parents = hfs_get_hl(key1->ParID) - hfs_get_hl(key2->ParID);
	if (parents != 0) {
		retval = (int)parents;
	} else {
		retval = hfs_strcmp(key1->CName.Name, key1->CName.Len,
				    key2->CName.Name, key2->CName.Len);
	}
	return retval;
}

/*
 * hfs_cat_build_key()
 *
 * Given the ID of the parent and the name build a search key.
 */
void hfs_cat_build_key(hfs_u32 parent, const struct hfs_name *cname,
		       struct hfs_cat_key *key)
{
	hfs_put_nl(parent, key->ParID);

	if (cname) {
		key->KeyLen = 6 + cname->Len;
		memcpy(&key->CName, cname, sizeof(*cname));
	} else {
		key->KeyLen = 6;
		memset(&key->CName, 0, sizeof(*cname));
	}
}

/*
 * hfs_cat_open()
 *
 * Given a directory on an HFS filesystem get its thread and
 * lock the directory against insertions and deletions.
 * Return 0 on success or an error code on failure.
 */
int hfs_cat_open(struct hfs_cat_entry *dir, struct hfs_brec *brec)
{
	struct hfs_cat_key key;
	int error;

	if (dir->type != HFS_CDR_DIR) {
		return -EINVAL;