603 lines
17 KiB
C
603 lines
17 KiB
C
/* VTreeFS - inode.c - by Alen Stojanov and David van Moolenbroek */
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#include "inc.h"
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/* The number of inodes and hash table slots. */
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static unsigned int nr_inodes;
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/* The table of all the inodes. */
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static struct inode *inode;
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/* The list of unused inodes. */
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static TAILQ_HEAD(unused_head, inode) unused_inodes;
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/* The hash tables for lookup of <parent,name> and <parent,index> to inode. */
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static LIST_HEAD(name_head, inode) *parent_name_head;
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static LIST_HEAD(index_head, inode) *parent_index_head;
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/* Internal integrity check. */
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#define CHECK_INODE(node) \
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do { \
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assert(node >= &inode[0] && node < &inode[nr_inodes]); \
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assert(node == &inode[0] || \
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node->i_parent != NULL || \
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(node->i_flags & I_DELETED)); \
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} while (0);
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/*===========================================================================*
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* init_inodes *
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*===========================================================================*/
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void init_inodes(unsigned int inodes, struct inode_stat *stat,
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index_t nr_indexed_entries)
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{
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/* Initialize the inode-related state.
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*/
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struct inode *node;
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int i;
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assert(inodes > 0);
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assert(nr_indexed_entries >= 0);
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nr_inodes = inodes;
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/* Allocate the inode and hash tables. */
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inode = malloc(nr_inodes * sizeof(inode[0]));
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parent_name_head = malloc(nr_inodes * sizeof(parent_name_head[0]));
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parent_index_head = malloc(nr_inodes * sizeof(parent_index_head[0]));
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assert(inode != NULL);
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assert(parent_name_head != NULL);
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assert(parent_index_head != NULL);
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#if DEBUG
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printf("VTREEFS: allocated %d+%d+%d bytes\n",
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nr_inodes * sizeof(inode[0]),
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nr_inodes * sizeof(parent_name_head[0]),
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nr_inodes * sizeof(parent_index_head[0]));
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#endif
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/* Initialize the free/unused list. */
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TAILQ_INIT(&unused_inodes);
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/* Add free inodes to the unused/free list. Skip the root inode. */
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for (i = 1; i < nr_inodes; i++) {
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node = &inode[i];
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node->i_parent = NULL;
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node->i_count = 0;
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TAILQ_INIT(&node->i_children);
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TAILQ_INSERT_HEAD(&unused_inodes, node, i_unused);
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}
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/* Initialize the hash lists. */
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for (i = 0; i < nr_inodes; i++) {
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LIST_INIT(&parent_name_head[i]);
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LIST_INIT(&parent_index_head[i]);
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}
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/* Initialize the root inode. */
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node = &inode[0];
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node->i_parent = NULL;
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node->i_count = 0;
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TAILQ_INIT(&node->i_children);
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node->i_flags = 0;
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node->i_index = NO_INDEX;
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set_inode_stat(node, stat);
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node->i_indexed = nr_indexed_entries;
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node->i_cbdata = NULL;
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}
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/*===========================================================================*
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* cleanup_inodes *
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*===========================================================================*/
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void cleanup_inodes(void)
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{
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/* Clean up the inode-related state.
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*/
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/* Free the inode and hash tables. */
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free(parent_index_head);
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free(parent_name_head);
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free(inode);
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}
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/*===========================================================================*
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* parent_name_hash *
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*===========================================================================*/
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static int parent_name_hash(struct inode *parent, char *name)
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{
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/* Return the hash value of <parent,name> tuple.
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*/
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unsigned int name_hash;
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unsigned long parent_hash;
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/* The parent hash is a simple array entry; find its index. */
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parent_hash = parent - &inode[0];
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/* Use the sdbm algorithm to hash the name. */
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name_hash = sdbm_hash(name, strlen(name));
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return (parent_hash ^ name_hash) % nr_inodes;
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}
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/*===========================================================================*
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* parent_index_hash *
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*===========================================================================*/
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static int parent_index_hash(struct inode *parent, index_t index)
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{
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/* Return the hash value of a <parent,index> tuple.
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*/
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return ((parent - &inode[0]) ^ index) % nr_inodes;
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}
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/*===========================================================================*
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* purge_inode *
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*===========================================================================*/
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void purge_inode(struct inode *parent)
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{
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/* Delete a deletable inode to make room for a new inode.
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*/
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/* An inode is deletable if:
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* - it is in use;
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* - it is indexed;
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* - it is not the given parent inode;
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* - it has a zero reference count;
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* - it does not have any children.
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* The first point is true for all inodes, or we would not be here.
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* The latter two points also imply that I_DELETED is not set.
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*/
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static int last_checked = 0;
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struct inode *node;
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int count;
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assert(TAILQ_EMPTY(&unused_inodes));
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/* This should not happen often enough to warrant an extra linked list,
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* especially as maintenance of that list would be rather error-prone..
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*/
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for (count = 0; count < nr_inodes; count++) {
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node = &inode[last_checked];
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last_checked = (last_checked + 1) % nr_inodes;
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if (node != parent && node->i_index != NO_INDEX &&
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node->i_count == 0 && TAILQ_EMPTY(&node->i_children)) {
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assert(!(node->i_flags & I_DELETED));
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delete_inode(node);
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break;
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}
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}
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}
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/*===========================================================================*
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* add_inode *
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*===========================================================================*/
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struct inode *add_inode(struct inode *parent, char *name,
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index_t index, struct inode_stat *stat, index_t nr_indexed_entries,
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cbdata_t cbdata)
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{
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/* Add an inode.
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*/
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struct inode *newnode;
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int slot;
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CHECK_INODE(parent);
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assert(S_ISDIR(parent->i_stat.mode));
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assert(!(parent->i_flags & I_DELETED));
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assert(strlen(name) <= PNAME_MAX);
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assert(index >= 0 || index == NO_INDEX);
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assert(stat != NULL);
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assert(nr_indexed_entries >= 0);
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assert(get_inode_by_name(parent, name) == NULL);
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/* Get a free inode. Free one up if necessary. */
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if (TAILQ_EMPTY(&unused_inodes))
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purge_inode(parent);
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assert(!TAILQ_EMPTY(&unused_inodes));
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newnode = TAILQ_FIRST(&unused_inodes);
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TAILQ_REMOVE(&unused_inodes, newnode, i_unused);
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assert(newnode->i_count == 0);
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/* Copy the relevant data to the inode. */
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newnode->i_parent = parent;
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newnode->i_flags = 0;
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newnode->i_index = index;
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newnode->i_stat = *stat;
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newnode->i_indexed = nr_indexed_entries;
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newnode->i_cbdata = cbdata;
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strlcpy(newnode->i_name, name, sizeof(newnode->i_name));
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/* Add the inode to the list of children inodes of the parent. */
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TAILQ_INSERT_HEAD(&parent->i_children, newnode, i_siblings);
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/* Add the inode to the <parent,name> hash table. */
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slot = parent_name_hash(parent, name);
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LIST_INSERT_HEAD(&parent_name_head[slot], newnode, i_hname);
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/* Add the inode to the <parent,index> hash table. */
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if (index != NO_INDEX) {
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slot = parent_index_hash(parent, index);
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LIST_INSERT_HEAD(&parent_index_head[slot], newnode, i_hindex);
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}
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return newnode;
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}
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/*===========================================================================*
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* get_root_inode *
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*===========================================================================*/
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struct inode *get_root_inode(void)
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{
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/* Return the file system's root inode.
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*/
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/* The root node is always the first node in the inode table */
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return &inode[0];
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}
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/*===========================================================================*
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* get_inode_name *
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*===========================================================================*/
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char const *get_inode_name(struct inode *node)
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{
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/* Return the name that an inode has in its parent directory.
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*/
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CHECK_INODE(node);
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return node->i_name;
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}
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/*===========================================================================*
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* get_inode_index *
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*===========================================================================*/
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index_t get_inode_index(struct inode *node)
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{
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/* Return the index that an inode has in its parent directory.
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*/
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CHECK_INODE(node);
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return node->i_index;
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}
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/*===========================================================================*
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* get_inode_cbdata *
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*===========================================================================*/
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cbdata_t get_inode_cbdata(struct inode *node)
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{
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/* Return the callback data associated with the given inode.
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*/
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CHECK_INODE(node);
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return node->i_cbdata;
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}
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/*===========================================================================*
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* get_parent_inode *
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*===========================================================================*/
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struct inode *get_parent_inode(struct inode *node)
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{
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/* Return an inode's parent inode.
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*/
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CHECK_INODE(node);
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/* The root inode does not have parent. */
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if (node == &inode[0])
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return NULL;
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return node->i_parent;
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}
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/*===========================================================================*
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* get_first_inode *
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*===========================================================================*/
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struct inode *get_first_inode(struct inode *parent)
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{
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/* Return a directory's first (non-deleted) child inode.
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*/
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struct inode *node;
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CHECK_INODE(parent);
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assert(S_ISDIR(parent->i_stat.mode));
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node = TAILQ_FIRST(&parent->i_children);
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while (node != NULL && (node->i_flags & I_DELETED))
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node = TAILQ_NEXT(node, i_siblings);
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return node;
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}
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/*===========================================================================*
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* get_next_inode *
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*===========================================================================*/
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struct inode *get_next_inode(struct inode *previous)
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{
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/* Return a directory's next (non-deleted) child inode.
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*/
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struct inode *node;
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CHECK_INODE(previous);
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node = TAILQ_NEXT(previous, i_siblings);
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while (node != NULL && (node->i_flags & I_DELETED))
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node = TAILQ_NEXT(node, i_siblings);
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return node;
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}
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/*===========================================================================*
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* get_inode_number *
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*===========================================================================*/
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int get_inode_number(struct inode *node)
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{
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/* Return the inode number of the given inode.
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*/
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CHECK_INODE(node);
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return (int) (node - &inode[0]) + 1;
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}
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/*===========================================================================*
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* get_inode_stat *
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*===========================================================================*/
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void get_inode_stat(struct inode *node, struct inode_stat *stat)
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{
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/* Retrieve an inode's status.
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*/
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CHECK_INODE(node);
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*stat = node->i_stat;
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}
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/*===========================================================================*
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* set_inode_stat *
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*===========================================================================*/
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void set_inode_stat(struct inode *node, struct inode_stat *stat)
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{
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/* Set an inode's status.
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*/
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CHECK_INODE(node);
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node->i_stat = *stat;
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}
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/*===========================================================================*
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* get_inode_by_name *
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*===========================================================================*/
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struct inode *get_inode_by_name(struct inode *parent, char *name)
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{
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/* Look up an inode using a <parent,name> tuple.
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*/
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struct inode *node;
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int slot;
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CHECK_INODE(parent);
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assert(strlen(name) <= PNAME_MAX);
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assert(S_ISDIR(parent->i_stat.mode));
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/* Get the hash value, and search for the inode. */
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slot = parent_name_hash(parent, name);
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LIST_FOREACH(node, &parent_name_head[slot], i_hname) {
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if (parent == node->i_parent && !strcmp(name, node->i_name))
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return node; /* found */
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}
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return NULL;
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}
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/*===========================================================================*
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* get_inode_by_index *
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*===========================================================================*/
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struct inode *get_inode_by_index(struct inode *parent, index_t index)
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{
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/* Look up an inode using a <parent,index> tuple.
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*/
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struct inode *node;
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int slot;
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CHECK_INODE(parent);
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assert(S_ISDIR(parent->i_stat.mode));
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assert(index >= 0 && index < parent->i_indexed);
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/* Get the hash value, and search for the inode. */
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slot = parent_index_hash(parent, index);
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LIST_FOREACH(node, &parent_index_head[slot], i_hindex) {
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if (parent == node->i_parent && index == node->i_index)
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return node; /* found */
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}
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return NULL;
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}
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/*===========================================================================*
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* find_inode *
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*===========================================================================*/
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struct inode *find_inode(pino_t num)
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{
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/* Retrieve an inode by inode number.
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*/
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struct inode *node;
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node = &inode[num - 1];
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CHECK_INODE(node);
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return node;
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}
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/*===========================================================================*
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* get_inode *
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*===========================================================================*/
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struct inode *get_inode(pino_t num)
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{
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/* Retrieve an inode by inode number, and increase its reference count.
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*/
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struct inode *node;
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if ((node = find_inode(num)) == NULL)
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return NULL;
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node->i_count++;
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return node;
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}
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/*===========================================================================*
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* put_inode *
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*===========================================================================*/
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void put_inode(struct inode *node)
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{
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/* Decrease an inode's reference count.
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*/
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CHECK_INODE(node);
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assert(node->i_count > 0);
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node->i_count--;
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/* If the inode is scheduled for deletion, and has no more references,
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* actually delete it now.
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*/
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if ((node->i_flags & I_DELETED) && node->i_count == 0)
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delete_inode(node);
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}
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/*===========================================================================*
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* ref_inode *
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*===========================================================================*/
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void ref_inode(struct inode *node)
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{
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/* Increase an inode's reference count.
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*/
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CHECK_INODE(node);
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assert(node->i_count >= 0);
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node->i_count++;
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}
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/*===========================================================================*
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* unlink_inode *
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*===========================================================================*/
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static void unlink_inode(struct inode *node)
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{
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/* Unlink the given node from its parent, if it is still linked in.
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*/
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struct inode *parent;
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assert(node->i_flags & I_DELETED);
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parent = node->i_parent;
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if (parent == NULL)
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return;
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/* Delete the node from the parent list. */
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node->i_parent = NULL;
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TAILQ_REMOVE(&parent->i_children, node, i_siblings);
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/* Optionally recheck if the parent can now be deleted. */
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if (parent->i_flags & I_DELETED)
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delete_inode(parent);
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}
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/*===========================================================================*
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* delete_inode *
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*===========================================================================*/
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void delete_inode(struct inode *node)
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{
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/* Delete the given inode. If its reference count is nonzero, or it
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* still has children that cannot be deleted for the same reason, keep
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* the inode around for the time being. If the node is a directory,
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* keep around its parent so that we can still do a "cd .." out of it.
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* For these reasons, this function may be called on an inode more than
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* once before it is actually deleted.
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*/
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struct inode *cnode, *ctmp;
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CHECK_INODE(node);
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assert(node != &inode[0]);
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/* If the inode was not already scheduled for deletion,
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* partially remove the node.
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*/
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if (!(node->i_flags & I_DELETED)) {
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/* Remove any children first (before I_DELETED is set!). */
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TAILQ_FOREACH_SAFE(cnode, &node->i_children, i_siblings, ctmp)
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delete_inode(cnode);
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/* Unhash the inode from the <parent,name> table. */
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LIST_REMOVE(node, i_hname);
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/* Unhash the inode from the <parent,index> table if needed. */
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if (node->i_index != NO_INDEX)
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LIST_REMOVE(node, i_hindex);
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node->i_flags |= I_DELETED;
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/* If this inode is not a directory, we don't care about being
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* able to find its parent. Unlink it from the parent now.
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*/
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if (!S_ISDIR(node->i_stat.mode))
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unlink_inode(node);
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}
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if (node->i_count == 0 && TAILQ_EMPTY(&node->i_children)) {
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/* If this inode still has a parent at this point, unlink it
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* now; noone can possibly refer to it anymore.
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*/
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if (node->i_parent != NULL)
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unlink_inode(node);
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/* Delete the actual node. */
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TAILQ_INSERT_HEAD(&unused_inodes, node, i_unused);
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}
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}
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/*===========================================================================*
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* is_inode_deleted *
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*===========================================================================*/
|
|
int is_inode_deleted(struct inode *node)
|
|
{
|
|
/* Return whether the given inode has been deleted.
|
|
*/
|
|
|
|
return (node->i_flags & I_DELETED);
|
|
}
|
|
|
|
/*===========================================================================*
|
|
* fs_putnode *
|
|
*===========================================================================*/
|
|
int fs_putnode(void)
|
|
{
|
|
/* Find the inode specified by the request message, and decrease its
|
|
* reference count.
|
|
*/
|
|
struct inode *node;
|
|
|
|
/* Get the inode specified by its number. */
|
|
if ((node = find_inode(fs_m_in.REQ_INODE_NR)) == NULL)
|
|
return EINVAL;
|
|
|
|
/* Decrease the reference count. */
|
|
node->i_count -= fs_m_in.REQ_COUNT - 1;
|
|
|
|
assert(node->i_count > 0);
|
|
|
|
put_inode(node);
|
|
|
|
return OK;
|
|
}
|