#include <string.h>
#include <stdlib.h>
#include <stddef.h>
+#include <stdbool.h>
#include <unistd.h>
#include <time.h>
#include <fcntl.h>
};
struct lock_queue_element {
- struct lock_queue_element *next;
- pthread_cond_t cond;
+ struct lock_queue_element *next;
+ pthread_cond_t cond;
+ fuse_ino_t nodeid1;
+ const char *name1;
+ char **path1;
+ struct node **wnode1;
+ fuse_ino_t nodeid2;
+ const char *name2;
+ char **path2;
+ struct node **wnode2;
+ int err;
+ bool first_locked : 1;
+ bool second_locked : 1;
+ bool done : 1;
};
struct node_table {
struct fuse_fs *fs;
int nullpath_ok;
int utime_omit_ok;
- int curr_ticket;
struct lock_queue_element *lockq;
int pagesize;
struct list_head partial_slabs;
unsigned int is_hidden : 1;
unsigned int cache_valid : 1;
int treelock;
- int ticket;
char inline_name[32];
};
+#define TREELOCK_WRITE -1
+#define TREELOCK_WAIT_OFFSET INT_MIN
+
struct node_lru {
struct node node;
struct list_head lru;
}
static void unlock_path(struct fuse *f, fuse_ino_t nodeid, struct node *wnode,
- struct node *end, int ticket)
+ struct node *end)
{
struct node *node;
if (wnode) {
- assert(wnode->treelock == -1);
+ assert(wnode->treelock == TREELOCK_WRITE);
wnode->treelock = 0;
- if (!wnode->ticket)
- wnode->ticket = ticket;
}
for (node = get_node(f, nodeid);
node != end && node->nodeid != FUSE_ROOT_ID; node = node->parent) {
- assert(node->treelock > 0);
+ assert(node->treelock != 0);
+ assert(node->treelock != TREELOCK_WAIT_OFFSET);
+ assert(node->treelock != TREELOCK_WRITE);
node->treelock--;
- if (!node->ticket)
- node->ticket = ticket;
- }
-}
-
-static void release_tickets(struct fuse *f, fuse_ino_t nodeid,
- struct node *wnode, int ticket)
-{
- struct node *node;
-
- if (wnode) {
- if (wnode->ticket != ticket)
- return;
-
- wnode->ticket = 0;
- }
-
- for (node = get_node(f, nodeid);
- node->nodeid != FUSE_ROOT_ID; node = node->parent) {
- if (node->ticket != ticket)
- return;
- node->ticket = 0;
+ if (node->treelock == TREELOCK_WAIT_OFFSET)
+ node->treelock = 0;
}
}
static int try_get_path(struct fuse *f, fuse_ino_t nodeid, const char *name,
- char **path, struct node **wnodep, int ticket)
+ char **path, struct node **wnodep, bool need_lock)
{
unsigned bufsize = 256;
char *buf;
}
if (wnodep) {
- assert(ticket);
+ assert(need_lock);
wnode = lookup_node(f, nodeid, name);
if (wnode) {
- if (wnode->treelock != 0 ||
- (wnode->ticket && wnode->ticket != ticket)) {
- if (!wnode->ticket)
- wnode->ticket = ticket;
+ if (wnode->treelock != 0) {
+ if (wnode->treelock > 0)
+ wnode->treelock += TREELOCK_WAIT_OFFSET;
err = -EAGAIN;
goto out_free;
}
- wnode->treelock = -1;
- wnode->ticket = 0;
+ wnode->treelock = TREELOCK_WRITE;
}
}
if (s == NULL)
goto out_unlock;
- if (ticket) {
+ if (need_lock) {
err = -EAGAIN;
- if (node->treelock == -1 ||
- (node->ticket && node->ticket != ticket))
+ if (node->treelock < 0)
goto out_unlock;
node->treelock++;
- node->ticket = 0;
}
}
return 0;
out_unlock:
- if (ticket)
- unlock_path(f, nodeid, wnode, node, ticket);
+ if (need_lock)
+ unlock_path(f, nodeid, wnode, node);
out_free:
free(buf);
out_err:
- if (ticket && err != -EAGAIN)
- release_tickets(f, nodeid, wnode, ticket);
-
return err;
}
-static void wake_up_first(struct fuse *f)
+static void queue_element_unlock(struct fuse *f, struct lock_queue_element *qe)
{
- if (f->lockq)
- pthread_cond_signal(&f->lockq->cond);
+ struct node *wnode;
+
+ if (qe->first_locked) {
+ wnode = qe->wnode1 ? *qe->wnode1 : NULL;
+ unlock_path(f, qe->nodeid1, wnode, NULL);
+ }
+ if (qe->second_locked) {
+ wnode = qe->wnode2 ? *qe->wnode2 : NULL;
+ unlock_path(f, qe->nodeid2, wnode, NULL);
+ }
}
-static void wake_up_next(struct lock_queue_element *qe)
+static void queue_element_wakeup(struct fuse *f, struct lock_queue_element *qe)
{
- if (qe->next)
- pthread_cond_signal(&qe->next->cond);
+ int err;
+ bool first = (qe == f->lockq);
+
+ if (!qe->path1) {
+ /* Just waiting for it to be unlocked */
+ if (get_node(f, qe->nodeid1)->treelock == 0)
+ pthread_cond_signal(&qe->cond);
+
+ return;
+ }
+
+ if (!qe->first_locked) {
+ err = try_get_path(f, qe->nodeid1, qe->name1, qe->path1,
+ qe->wnode1, true);
+ if (!err)
+ qe->first_locked = true;
+ else if (err != -EAGAIN)
+ goto err_unlock;
+ }
+ if (!qe->second_locked && qe->path2) {
+ err = try_get_path(f, qe->nodeid2, qe->name2, qe->path2,
+ qe->wnode2, true);
+ if (!err)
+ qe->second_locked = true;
+ else if (err != -EAGAIN)
+ goto err_unlock;
+ }
+
+ if (qe->first_locked && (qe->second_locked || !qe->path2)) {
+ err = 0;
+ goto done;
+ }
+
+ /*
+ * Only let the first element be partially locked otherwise there could
+ * be a deadlock.
+ *
+ * But do allow the first element to be partially locked to prevent
+ * starvation.
+ */
+ if (!first)
+ queue_element_unlock(f, qe);
+
+ /* keep trying */
+ return;
+
+err_unlock:
+ queue_element_unlock(f, qe);
+done:
+ qe->err = err;
+ qe->done = true;
+ pthread_cond_signal(&qe->cond);
}
-static int get_ticket(struct fuse *f)
+static void wake_up_queued(struct fuse *f)
{
- do f->curr_ticket++;
- while (f->curr_ticket == 0);
+ struct lock_queue_element *qe;
- return f->curr_ticket;
+ for (qe = f->lockq; qe != NULL; qe = qe->next)
+ queue_element_wakeup(f, qe);
}
static void debug_path(struct fuse *f, const char *msg, fuse_ino_t nodeid,
- const char *name, int wr)
+ const char *name, bool wr)
{
if (f->conf.debug) {
struct node *wnode = NULL;
}
}
-static void queue_path(struct fuse *f, struct lock_queue_element *qe,
- fuse_ino_t nodeid, const char *name, int wr)
+static void queue_path(struct fuse *f, struct lock_queue_element *qe)
{
struct lock_queue_element **qp;
- debug_path(f, "QUEUE PATH", nodeid, name, wr);
+ qe->done = false;
+ qe->first_locked = false;
+ qe->second_locked = false;
pthread_cond_init(&qe->cond, NULL);
qe->next = NULL;
for (qp = &f->lockq; *qp != NULL; qp = &(*qp)->next);
*qp = qe;
}
-static void dequeue_path(struct fuse *f, struct lock_queue_element *qe,
- fuse_ino_t nodeid, const char *name, int wr)
+static void dequeue_path(struct fuse *f, struct lock_queue_element *qe)
{
struct lock_queue_element **qp;
- debug_path(f, "DEQUEUE PATH", nodeid, name, wr);
pthread_cond_destroy(&qe->cond);
for (qp = &f->lockq; *qp != qe; qp = &(*qp)->next);
*qp = qe->next;
}
-static void wait_on_path(struct fuse *f, struct lock_queue_element *qe,
- fuse_ino_t nodeid, const char *name, int wr)
+static int wait_path(struct fuse *f, struct lock_queue_element *qe)
{
- debug_path(f, "WAIT ON PATH", nodeid, name, wr);
- pthread_cond_wait(&qe->cond, &f->lock);
+ queue_path(f, qe);
+
+ do {
+ pthread_cond_wait(&qe->cond, &f->lock);
+ } while (!qe->done);
+
+ dequeue_path(f, qe);
+
+ return qe->err;
}
static int get_path_common(struct fuse *f, fuse_ino_t nodeid, const char *name,
char **path, struct node **wnode)
{
int err;
- int ticket;
pthread_mutex_lock(&f->lock);
- ticket = get_ticket(f);
- err = try_get_path(f, nodeid, name, path, wnode, ticket);
+ err = try_get_path(f, nodeid, name, path, wnode, true);
if (err == -EAGAIN) {
- struct lock_queue_element qe;
-
- queue_path(f, &qe, nodeid, name, !!wnode);
- do {
- wait_on_path(f, &qe, nodeid, name, !!wnode);
- err = try_get_path(f, nodeid, name, path, wnode,
- ticket);
- wake_up_next(&qe);
- } while (err == -EAGAIN);
- dequeue_path(f, &qe, nodeid, name, !!wnode);
+ struct lock_queue_element qe = {
+ .nodeid1 = nodeid,
+ .name1 = name,
+ .path1 = path,
+ .wnode1 = wnode,
+ };
+ debug_path(f, "QUEUE PATH", nodeid, name, !!wnode);
+ err = wait_path(f, &qe);
+ debug_path(f, "DEQUEUE PATH", nodeid, name, !!wnode);
}
pthread_mutex_unlock(&f->lock);
static int try_get_path2(struct fuse *f, fuse_ino_t nodeid1, const char *name1,
fuse_ino_t nodeid2, const char *name2,
char **path1, char **path2,
- struct node **wnode1, struct node **wnode2,
- int ticket)
+ struct node **wnode1, struct node **wnode2)
{
int err;
/* FIXME: locking two paths needs deadlock checking */
- err = try_get_path(f, nodeid1, name1, path1, wnode1, ticket);
+ err = try_get_path(f, nodeid1, name1, path1, wnode1, true);
if (!err) {
- err = try_get_path(f, nodeid2, name2, path2, wnode2, ticket);
+ err = try_get_path(f, nodeid2, name2, path2, wnode2, true);
if (err) {
struct node *wn1 = wnode1 ? *wnode1 : NULL;
- unlock_path(f, nodeid1, wn1, NULL, ticket);
+ unlock_path(f, nodeid1, wn1, NULL);
free(*path1);
- if (ticket && err != -EAGAIN)
- release_tickets(f, nodeid1, wn1, ticket);
}
}
return err;
struct node **wnode1, struct node **wnode2)
{
int err;
- int ticket;
pthread_mutex_lock(&f->lock);
- ticket = get_ticket(f);
err = try_get_path2(f, nodeid1, name1, nodeid2, name2,
- path1, path2, wnode1, wnode2, ticket);
+ path1, path2, wnode1, wnode2);
if (err == -EAGAIN) {
- struct lock_queue_element qe;
+ struct lock_queue_element qe = {
+ .nodeid1 = nodeid1,
+ .name1 = name1,
+ .path1 = path1,
+ .wnode1 = wnode1,
+ .nodeid2 = nodeid2,
+ .name2 = name2,
+ .path2 = path2,
+ .wnode2 = wnode2,
+ };
- queue_path(f, &qe, nodeid1, name1, !!wnode1);
- debug_path(f, " path2", nodeid2, name2, !!wnode2);
- do {
- wait_on_path(f, &qe, nodeid1, name1, !!wnode1);
- debug_path(f, " path2", nodeid2, name2, !!wnode2);
- err = try_get_path2(f, nodeid1, name1, nodeid2, name2,
- path1, path2, wnode1, wnode2,
- ticket);
- wake_up_next(&qe);
- } while (err == -EAGAIN);
- dequeue_path(f, &qe, nodeid1, name1, !!wnode1);
- debug_path(f, " path2", nodeid2, name2, !!wnode2);
+ debug_path(f, "QUEUE PATH1", nodeid1, name1, !!wnode1);
+ debug_path(f, " PATH2", nodeid2, name2, !!wnode2);
+ err = wait_path(f, &qe);
+ debug_path(f, "DEQUEUE PATH1", nodeid1, name1, !!wnode1);
+ debug_path(f, " PATH2", nodeid2, name2, !!wnode2);
}
pthread_mutex_unlock(&f->lock);
struct node *wnode, char *path)
{
pthread_mutex_lock(&f->lock);
- unlock_path(f, nodeid, wnode, NULL, 0);
- wake_up_first(f);
+ unlock_path(f, nodeid, wnode, NULL);
+ if (f->lockq)
+ wake_up_queued(f);
pthread_mutex_unlock(&f->lock);
free(path);
}
char *path1, char *path2)
{
pthread_mutex_lock(&f->lock);
- unlock_path(f, nodeid1, wnode1, NULL, 0);
- unlock_path(f, nodeid2, wnode2, NULL, 0);
- wake_up_first(f);
+ unlock_path(f, nodeid1, wnode1, NULL);
+ unlock_path(f, nodeid2, wnode2, NULL);
+ wake_up_queued(f);
pthread_mutex_unlock(&f->lock);
free(path1);
free(path2);
* create and opendir
*/
while (node->nlookup == nlookup && node->treelock) {
- struct lock_queue_element qe;
+ struct lock_queue_element qe = {
+ .nodeid1 = nodeid,
+ };
- queue_path(f, &qe, node->nodeid, NULL, 0);
- do {
- wait_on_path(f, &qe, node->nodeid, NULL, 0);
- wake_up_next(&qe);
+ debug_path(f, "QUEUE PATH (forget)", nodeid, NULL, false);
+ queue_path(f, &qe);
+ do {
+ pthread_cond_wait(&qe.cond, &f->lock);
} while (node->nlookup == nlookup && node->treelock);
- dequeue_path(f, &qe, node->nodeid, NULL, 0);
+
+ dequeue_path(f, &qe);
+ debug_path(f, "DEQUEUE_PATH (forget)", nodeid, NULL, false);
}
assert(node->nlookup >= nlookup);
newnode = lookup_node(f, dir, newname);
} while(newnode);
- res = try_get_path(f, dir, newname, &newpath, NULL, 0);
+ res = try_get_path(f, dir, newname, &newpath, NULL, false);
pthread_mutex_unlock(&f->lock);
if (res)
break;
node = node->id_next) {
if (node->is_hidden) {
char *path;
- if (try_get_path(f, node->nodeid, NULL, &path, NULL, 0) == 0) {
+ if (try_get_path(f, node->nodeid, NULL, &path, NULL, false) == 0) {
fuse_fs_unlink(f->fs, path);
free(path);
}
projects / qemu-gpiodev / libfuse.git / commitdiff