Switch to 31-bit directory cookies and a separate hashtable for lookups.

[bluesky.git] / inode.c

diff --git a/inode.c b/inode.c
index ec90757..aa822b7 100644 (file)
--- a/inode.c
+++ b/inode.c
@@ -21,7 +21,52 @@ int64_t bluesky_get_current_time()
 {
     GTimeVal t;
     g_get_current_time(&t);
-    return t.tv_sec * 1000000 + t.tv_usec;
+    return (int64_t)t.tv_sec * 1000000 + t.tv_usec;
+}
+
+/* Update an inode to indicate that a modification was made.  This increases
+ * the change counter, updates the ctime to the current time, and optionally
+ * updates the mtime. */
+void bluesky_inode_update_ctime(BlueSkyInode *inode, gboolean update_mtime)
+{
+    int64_t now = bluesky_get_current_time();
+    inode->change_count++;
+    inode->ctime = now;
+    if (update_mtime)
+        inode->mtime = now;
+}
+
+/* Unfortunately a glib hash table is only guaranteed to be able to store
+ * 32-bit keys if we use the key directly.  If we want 64-bit inode numbers,
+ * we'll have to allocate memory to store the 64-bit inumber, and use a pointer
+ * to it.  Rather than allocate the memory for the key, we'll just include a
+ * pointer to the 64-bit inum stored in the inode itself, so that we don't need
+ * to do any more memory management.  */
+static guint bluesky_fs_key_hash_func(gconstpointer key)
+{
+    uint64_t inum = *(const uint64_t *)key;
+    return (guint)inum;
+}
+
+static gboolean bluesky_fs_key_equal_func(gconstpointer a, gconstpointer b)
+{
+    uint64_t i1 = *(const uint64_t *)a;
+    uint64_t i2 = *(const uint64_t *)b;
+    return i1 == i2;
+}
+
+/* Filesystem-level operations.  A filesystem is like a directory tree that we
+ * are willing to export. */
+BlueSkyFS *bluesky_new_fs(gchar *name)
+{
+    BlueSkyFS *fs = g_new0(BlueSkyFS, 1);
+    fs->lock = g_mutex_new();
+    fs->name = g_strdup(name);
+    fs->inodes = g_hash_table_new(bluesky_fs_key_hash_func,
+                                  bluesky_fs_key_equal_func);
+    fs->next_inum = BLUESKY_ROOT_INUM + 1;
+
+    return fs;
 }
 
 /* Allocate a fresh inode number which has not been used before within a
@@ -38,12 +83,83 @@ uint64_t bluesky_fs_alloc_inode(BlueSkyFS *fs)
     return inum;
 }
 
-BlueSkyInode *bluesky_new_inode(uint64_t inum)
+BlueSkyInode *bluesky_new_inode(uint64_t inum, BlueSkyFileType type)
 {
     BlueSkyInode *i = g_new0(BlueSkyInode, 1);
 
     i->lock = g_mutex_new();
+    i->type = type;
     i->inum = inum;
 
+    switch (type) {
+    case BLUESKY_REGULAR:
+        i->blocks = g_array_new(FALSE, TRUE, sizeof(BlueSkyBlock));
+        break;
+    case BLUESKY_DIRECTORY:
+        i->dirents = g_sequence_new(bluesky_dirent_destroy);
+        i->dirhash = g_hash_table_new(g_str_hash, g_str_equal);
+        break;
+    case BLUESKY_BLOCK:
+    case BLUESKY_CHARACTER:
+    case BLUESKY_SYMLINK:
+    case BLUESKY_SOCKET:
+    case BLUESKY_FIFO:
+        break;
+    }
+
     return i;
 }
+
+/* Retrieve an inode from the filesystem.  Eventually this will be a cache and
+ * so we might need to go fetch the inode from elsewhere; for now all
+ * filesystem state is stored here. */
+BlueSkyInode *bluesky_get_inode(BlueSkyFS *fs, uint64_t inum)
+{
+    BlueSkyInode *inode = NULL;
+
+    g_mutex_lock(fs->lock);
+    inode = (BlueSkyInode *)g_hash_table_lookup(fs->inodes, &inum);
+    g_mutex_unlock(fs->lock);
+
+    return inode;
+}
+
+/* Insert an inode into the filesystem inode cache. */
+void bluesky_insert_inode(BlueSkyFS *fs, BlueSkyInode *inode)
+{
+    g_mutex_lock(fs->lock);
+    g_hash_table_insert(fs->inodes, &inode->inum, inode);
+    g_mutex_unlock(fs->lock);
+}
+
+/* Set the size of a file.  This will truncate or extend the file as needed.
+ * Newly-allocated bytes are zeroed. */
+void bluesky_file_truncate(BlueSkyInode *inode, uint64_t size)
+{
+    g_return_if_fail(size <= BLUESKY_MAX_FILE_SIZE);
+
+    if (size == inode->size)
+        return;
+
+    uint64_t blocks = (size + BLUESKY_BLOCK_SIZE - 1) / BLUESKY_MAX_FILE_SIZE;
+
+    if (blocks > inode->blocks->len) {
+        /* Need to add new blocks to the end of a file.  New block structures
+         * are automatically zeroed, which initializes them to be pointers to
+         * zero blocks so we don't need to do any more work. */
+        g_array_set_size(inode->blocks, blocks);
+    } else if (blocks < inode->blocks->len) {
+        /* Delete blocks from a file.  Must reclaim memory. */
+        for (guint i = inode->blocks->len; i < blocks; i++) {
+            BlueSkyBlock *b = &g_array_index(inode->blocks, BlueSkyBlock, i);
+            g_free(b->ref);
+            g_free(b->data);
+        }
+        g_array_set_size(inode->blocks, blocks);
+    }
+
+    /* TODO: Zero out partial blocks if needed? */
+
+    inode->size = size;
+    inode->change_count++;
+}