minix/lib/libvtreefs/inode.c

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/* VTreeFS - inode.c - by Alen Stojanov and David van Moolenbroek */
#include "inc.h"
/* 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;
static LIST_HEAD(index_head, inode) *parent_index_head;
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/* 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 *
*===========================================================================*/
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void init_inodes(unsigned int inodes, struct inode_stat *stat,
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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 *
*===========================================================================*/
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void cleanup_inodes(void)
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{
/* 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 *
*===========================================================================*/
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static int parent_name_hash(struct inode *parent, char *name)
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{
/* 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 *
*===========================================================================*/
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static int parent_index_hash(struct inode *parent, index_t index)
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{
/* Return the hash value of a <parent,index> tuple.
*/
return ((parent - &inode[0]) ^ index) % nr_inodes;
}
/*===========================================================================*
* purge_inode *
*===========================================================================*/
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void purge_inode(struct inode *parent)
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{
/* 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 *
*===========================================================================*/
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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,
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;
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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. */
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 *
*===========================================================================*/
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struct inode *get_root_inode(void)
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{
/* 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 *
*===========================================================================*/
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char const *get_inode_name(struct inode *node)
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{
/* Return the name that an inode has in its parent directory.
*/
CHECK_INODE(node);
return node->i_name;
}
/*===========================================================================*
* get_inode_index *
*===========================================================================*/
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index_t get_inode_index(struct inode *node)
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{
/* Return the index that an inode has in its parent directory.
*/
CHECK_INODE(node);
return node->i_index;
}
/*===========================================================================*
* get_inode_cbdata *
*===========================================================================*/
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cbdata_t get_inode_cbdata(struct inode *node)
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{
/* Return the callback data associated with the given inode.
*/
CHECK_INODE(node);
return node->i_cbdata;
}
/*===========================================================================*
* get_parent_inode *
*===========================================================================*/
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struct inode *get_parent_inode(struct inode *node)
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{
/* 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 *
*===========================================================================*/
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struct inode *get_first_inode(struct inode *parent)
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{
/* 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 *
*===========================================================================*/
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struct inode *get_next_inode(struct inode *previous)
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{
/* 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 *
*===========================================================================*/
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int get_inode_number(struct inode *node)
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{
/* Return the inode number of the given inode.
*/
CHECK_INODE(node);
return (int) (node - &inode[0]) + 1;
}
/*===========================================================================*
* get_inode_stat *
*===========================================================================*/
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void get_inode_stat(struct inode *node, struct inode_stat *stat)
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{
/* Retrieve an inode's status.
*/
CHECK_INODE(node);
*stat = node->i_stat;
}
/*===========================================================================*
* set_inode_stat *
*===========================================================================*/
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void set_inode_stat(struct inode *node, struct inode_stat *stat)
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{
/* Set an inode's status.
*/
CHECK_INODE(node);
node->i_stat = *stat;
}
/*===========================================================================*
* get_inode_by_name *
*===========================================================================*/
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struct inode *get_inode_by_name(struct inode *parent, char *name)
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{
/* 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 *
*===========================================================================*/
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struct inode *get_inode_by_index(struct inode *parent, index_t index)
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{
/* 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 *
*===========================================================================*/
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struct inode *find_inode(ino_t num)
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{
/* Retrieve an inode by inode number.
*/
struct inode *node;
node = &inode[num - 1];
CHECK_INODE(node);
return node;
}
/*===========================================================================*
* get_inode *
*===========================================================================*/
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struct inode *get_inode(ino_t num)
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{
/* 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 *
*===========================================================================*/
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void put_inode(struct inode *node)
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{
/* 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 *
*===========================================================================*/
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void ref_inode(struct inode *node)
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{
/* Increase an inode's reference count.
*/
CHECK_INODE(node);
assert(node->i_count >= 0);
node->i_count++;
}
/*===========================================================================*
* unlink_inode *
*===========================================================================*/
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static void unlink_inode(struct inode *node)
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{
/* 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 *
*===========================================================================*/
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void delete_inode(struct inode *node)
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{
/* 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 *
*===========================================================================*/
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int is_inode_deleted(struct inode *node)
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{
/* Return whether the given inode has been deleted.
*/
return (node->i_flags & I_DELETED);
}
/*===========================================================================*
* fs_putnode *
*===========================================================================*/
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int fs_putnode(void)
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{
/* 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;
}