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