WebSVN – HelenOS – Diff – /branches/tracing/uspace/srv/fs/fat/fat_idx.c



 
    /** Sorted list of intervals of freed indices. */
    link_t      freed_head;
} unused_t;
 
/** Futex protecting the list of unused structures. */
static futex_t unused_futex = FUTEX_INITIALIZER;
 
/** List of unused structures. */
static LIST_INITIALIZE(unused_head);
 
/** Futex protecting the up_hash and ui_hash. */
static futex_t used_futex = FUTEX_INITIALIZER;
 
/**
 * Global hash table of all used fat_idx_t structures.
 * The index structures are hashed by the dev_handle, parent node's first
 * cluster and index within the parent directory.
 */

{
    link_t *l;
    unused_t *u;
   
    assert(index);
    futex_down(&unused_futex);
    for (l = unused_head.next; l != &unused_head; l = l->next) {
        u = list_get_instance(l, unused_t, link);
        if (u->dev_handle == dev_handle)
            goto hit;
    }
    futex_up(&unused_futex);
   
    /* dev_handle not found */
    return false;  
 
hit:
    if (list_empty(&u->freed_head)) {

             * There are no freed indices, allocate one directly
             * from the counter.
             */
            *index = u->next++;
            --u->remaining;
            futex_up(&unused_futex);
            return true;
        }
    } else {
        /* There are some freed indices which we can reuse. */
        freed_t *f = list_get_instance(u->freed_head.next, freed_t,

        if (f->first++ == f->last) {
            /* Destroy the interval. */
            list_remove(&f->link);
            free(f);
        }
        futex_up(&unused_futex);
        return true;
    }
    /*
     * We ran out of indices, which is extremely unlikely with FAT16, but
     * theoretically still possible (e.g. too many open unlinked nodes or
     * too many zero-sized nodes).
     */
    futex_up(&unused_futex);
    return false;
}
 
/** If possible, coalesce two intervals of freed indices. */
static void try_coalesce_intervals(link_t *l, link_t *r, link_t *cur)

static void fat_idx_free(dev_handle_t dev_handle, fs_index_t index)
{
    link_t *l;
    unused_t *u;
 
    futex_down(&unused_futex);
    for (l = unused_head.next; l != &unused_head; l = l->next) {
        u = list_get_instance(l, unused_t, link);
        if (u->dev_handle == dev_handle)
            goto hit;
    }
    futex_up(&unused_futex);
 
    /* should not happen */
    assert(0);
 
hit:
    if (u->next == index + 1) {
        /* The index can be returned directly to the counter. */
        u->next--;
        u->remaining++;
 
    } else {
        /*
         * The index must be returned either to an existing freed
         * interval or a new interval must be created.
         */

            if (f->first == index + 1) {
                f->first--;
                if (lnk->prev != &u->freed_head)
                    try_coalesce_intervals(lnk->prev, lnk,
                        lnk);
                futex_up(&unused_futex);
                return;
            }
            if (f->last == index - 1) {
                f->last++;
                if (lnk->next != &u->freed_head)
                    try_coalesce_intervals(lnk, lnk->next,
                        lnk);
                futex_up(&unused_futex);
                return;
            }
            if (index > f->first) {
                n = malloc(sizeof(freed_t));
                /* TODO: sleep until allocation succeeds */
                assert(n);
                link_initialize(&n->link);
                n->first = index;
                n->last = index;
                list_insert_before(&n->link, lnk);
                futex_up(&unused_futex);
                return;
            }
 
        }
        /* The index will form the last interval. */

        link_initialize(&n->link);
        n->first = index;
        n->last = index;
        list_append(&n->link, &u->freed_head);
    }
    futex_up(&unused_futex);
}
 
fat_idx_t *
fat_idx_get_by_pos(dev_handle_t dev_handle, fat_cluster_t pfc, unsigned pdi)
{

        [UPH_DH_KEY] = dev_handle,
        [UPH_PFC_KEY] = pfc,
        [UPH_PDI_KEY] = pdi,
    };
 
    futex_down(&used_futex);
    l = hash_table_find(&up_hash, pkey);
    if (l) {
        fidx = hash_table_get_instance(l, fat_idx_t, uph_link);
    } else {
        fidx = (fat_idx_t *) malloc(sizeof(fat_idx_t));
        if (!fidx) {
            futex_up(&used_futex);
            return NULL;
        }
        if (!fat_idx_alloc(dev_handle, &fidx->index)) {
            free(fidx);
            futex_up(&used_futex);
            return NULL;
        }
       
        unsigned long ikey[] = {
            [UIH_DH_KEY] = dev_handle,
            [UIH_INDEX_KEY] = fidx->index,
        };
   
        link_initialize(&fidx->uph_link);
        link_initialize(&fidx->uih_link);
        futex_initialize(&fidx->lock, 1);
        fidx->dev_handle = dev_handle;
        fidx->pfc = pfc;
        fidx->pdi = pdi;
        fidx->nodep = NULL;
 
        hash_table_insert(&up_hash, pkey, &fidx->uph_link);
        hash_table_insert(&ui_hash, ikey, &fidx->uih_link);
    }
    futex_down(&fidx->lock);
    futex_up(&used_futex);
 
    return fidx;
}
 
fat_idx_t *

    unsigned long ikey[] = {
        [UIH_DH_KEY] = dev_handle,
        [UIH_INDEX_KEY] = index,
    };
 
    futex_down(&used_futex);
    l = hash_table_find(&ui_hash, ikey);
    if (l) {
        fidx = hash_table_get_instance(l, fat_idx_t, uih_link);
        futex_down(&fidx->lock);
    }
    futex_up(&used_futex);
 
    return fidx;
}
 

Rev 2925	Rev 3011
Line 66...	Line 66...
66		66
67	/** Sorted list of intervals of freed indices. */	67	/** Sorted list of intervals of freed indices. */
68	link_t freed_head;	68	link_t freed_head;
69	} unused_t;	69	} unused_t;
70		70
-		71	/** Futex protecting the list of unused structures. */
-		72	static futex_t unused_futex = FUTEX_INITIALIZER;
-		73
-		74	/** List of unused structures. */
71	static LIST_INITIALIZE(unused_head);	75	static LIST_INITIALIZE(unused_head);
72		76
-		77	/** Futex protecting the up_hash and ui_hash. */
-		78	static futex_t used_futex = FUTEX_INITIALIZER;
-		79
73	/**	80	/**
74	* Global hash table of all used fat_idx_t structures.	81	* Global hash table of all used fat_idx_t structures.
75	* The index structures are hashed by the dev_handle, parent node's first	82	* The index structures are hashed by the dev_handle, parent node's first
76	* cluster and index within the parent directory.	83	* cluster and index within the parent directory.
77	*/	84	*/
Line 185...	Line 192...
185	{	192	{
186	link_t *l;	193	link_t *l;
187	unused_t *u;	194	unused_t *u;
188		195
189	assert(index);	196	assert(index);
-		197	futex_down(&unused_futex);
190	for (l = unused_head.next; l != &unused_head; l = l->next) {	198	for (l = unused_head.next; l != &unused_head; l = l->next) {
191	u = list_get_instance(l, unused_t, link);	199	u = list_get_instance(l, unused_t, link);
192	if (u->dev_handle == dev_handle)	200	if (u->dev_handle == dev_handle)
193	goto hit;	201	goto hit;
194	}	202	}
-		203	futex_up(&unused_futex);
195		204
196	/* dev_handle not found */	205	/* dev_handle not found */
197	return false;	206	return false;
198		207
199	hit:	208	hit:
200	if (list_empty(&u->freed_head)) {	209	if (list_empty(&u->freed_head)) {
Line 203...	Line 212...
203	* There are no freed indices, allocate one directly	212	* There are no freed indices, allocate one directly
204	* from the counter.	213	* from the counter.
205	*/	214	*/
206	*index = u->next++;	215	*index = u->next++;
207	--u->remaining;	216	--u->remaining;
-		217	futex_up(&unused_futex);
208	return true;	218	return true;
209	}	219	}
210	} else {	220	} else {
211	/* There are some freed indices which we can reuse. */	221	/* There are some freed indices which we can reuse. */
212	freed_t *f = list_get_instance(u->freed_head.next, freed_t,	222	freed_t *f = list_get_instance(u->freed_head.next, freed_t,
Line 215...	Line 225...
215	if (f->first++ == f->last) {	225	if (f->first++ == f->last) {
216	/* Destroy the interval. */	226	/* Destroy the interval. */
217	list_remove(&f->link);	227	list_remove(&f->link);
218	free(f);	228	free(f);
219	}	229	}
-		230	futex_up(&unused_futex);
220	return true;	231	return true;
221	}	232	}
222	/*	233	/*
223	* We ran out of indices, which is extremely unlikely with FAT16, but	234	* We ran out of indices, which is extremely unlikely with FAT16, but
224	* theoretically still possible (e.g. too many open unlinked nodes or	235	* theoretically still possible (e.g. too many open unlinked nodes or
225	* too many zero-sized nodes).	236	* too many zero-sized nodes).
226	*/	237	*/
-		238	futex_up(&unused_futex);
227	return false;	239	return false;
228	}	240	}
229		241
230	/** If possible, coalesce two intervals of freed indices. */	242	/** If possible, coalesce two intervals of freed indices. */
231	static void try_coalesce_intervals(link_t l, link_t r, link_t *cur)	243	static void try_coalesce_intervals(link_t l, link_t r, link_t *cur)
Line 250...	Line 262...
250	static void fat_idx_free(dev_handle_t dev_handle, fs_index_t index)	262	static void fat_idx_free(dev_handle_t dev_handle, fs_index_t index)
251	{	263	{
252	link_t *l;	264	link_t *l;
253	unused_t *u;	265	unused_t *u;
254		266
-		267	futex_down(&unused_futex);
255	for (l = unused_head.next; l != &unused_head; l = l->next) {	268	for (l = unused_head.next; l != &unused_head; l = l->next) {
256	u = list_get_instance(l, unused_t, link);	269	u = list_get_instance(l, unused_t, link);
257	if (u->dev_handle == dev_handle)	270	if (u->dev_handle == dev_handle)
258	goto hit;	271	goto hit;
259	}	272	}
-		273	futex_up(&unused_futex);
260		274
261	/* should not happen */	275	/* should not happen */
262	assert(0);	276	assert(0);
263		277
264	hit:	278	hit:
265	if (u->next == index + 1) {	279	if (u->next == index + 1) {
266	/* The index can be returned directly to the counter. */	280	/* The index can be returned directly to the counter. */
267	u->next--;	281	u->next--;
268	u->remaining++;	282	u->remaining++;
269	return;	-
270	} else {	283	} else {
271	/*	284	/*
272	* The index must be returned either to an existing freed	285	* The index must be returned either to an existing freed
273	* interval or a new interval must be created.	286	* interval or a new interval must be created.
274	*/	287	*/
Line 280...	Line 293...
280	if (f->first == index + 1) {	293	if (f->first == index + 1) {
281	f->first--;	294	f->first--;
282	if (lnk->prev != &u->freed_head)	295	if (lnk->prev != &u->freed_head)
283	try_coalesce_intervals(lnk->prev, lnk,	296	try_coalesce_intervals(lnk->prev, lnk,
284	lnk);	297	lnk);
-		298	futex_up(&unused_futex);
285	return;	299	return;
286	}	300	}
287	if (f->last == index - 1) {	301	if (f->last == index - 1) {
288	f->last++;	302	f->last++;
289	if (lnk->next != &u->freed_head)	303	if (lnk->next != &u->freed_head)
290	try_coalesce_intervals(lnk, lnk->next,	304	try_coalesce_intervals(lnk, lnk->next,
291	lnk);	305	lnk);
-		306	futex_up(&unused_futex);
292	return;	307	return;
293	}	308	}
294	if (index > f->first) {	309	if (index > f->first) {
295	n = malloc(sizeof(freed_t));	310	n = malloc(sizeof(freed_t));
296	/* TODO: sleep until allocation succeeds */	311	/* TODO: sleep until allocation succeeds */
297	assert(n);	312	assert(n);
298	link_initialize(&n->link);	313	link_initialize(&n->link);
299	n->first = index;	314	n->first = index;
300	n->last = index;	315	n->last = index;
301	list_insert_before(&n->link, lnk);	316	list_insert_before(&n->link, lnk);
-		317	futex_up(&unused_futex);
302	return;	318	return;
303	}	319	}
304		320
305	}	321	}
306	/* The index will form the last interval. */	322	/* The index will form the last interval. */
Line 310...	Line 326...
310	link_initialize(&n->link);	326	link_initialize(&n->link);
311	n->first = index;	327	n->first = index;
312	n->last = index;	328	n->last = index;
313	list_append(&n->link, &u->freed_head);	329	list_append(&n->link, &u->freed_head);
314	}	330	}
-		331	futex_up(&unused_futex);
315	}	332	}
316		333
317	fat_idx_t *	334	fat_idx_t *
318	fat_idx_get_by_pos(dev_handle_t dev_handle, fat_cluster_t pfc, unsigned pdi)	335	fat_idx_get_by_pos(dev_handle_t dev_handle, fat_cluster_t pfc, unsigned pdi)
319	{	336	{
Line 323...	Line 340...
323	[UPH_DH_KEY] = dev_handle,	340	[UPH_DH_KEY] = dev_handle,
324	[UPH_PFC_KEY] = pfc,	341	[UPH_PFC_KEY] = pfc,
325	[UPH_PDI_KEY] = pdi,	342	[UPH_PDI_KEY] = pdi,
326	};	343	};
327		344
-		345	futex_down(&used_futex);
328	l = hash_table_find(&up_hash, pkey);	346	l = hash_table_find(&up_hash, pkey);
329	if (l) {	347	if (l) {
330	fidx = hash_table_get_instance(l, fat_idx_t, uph_link);	348	fidx = hash_table_get_instance(l, fat_idx_t, uph_link);
331	} else {	349	} else {
332	fidx = (fat_idx_t *) malloc(sizeof(fat_idx_t));	350	fidx = (fat_idx_t *) malloc(sizeof(fat_idx_t));
333	if (!fidx) {	351	if (!fidx) {
-		352	futex_up(&used_futex);
334	return NULL;	353	return NULL;
335	}	354	}
336	if (!fat_idx_alloc(dev_handle, &fidx->index)) {	355	if (!fat_idx_alloc(dev_handle, &fidx->index)) {
337	free(fidx);	356	free(fidx);
-		357	futex_up(&used_futex);
338	return NULL;	358	return NULL;
339	}	359	}
340		360
341	unsigned long ikey[] = {	361	unsigned long ikey[] = {
342	[UIH_DH_KEY] = dev_handle,	362	[UIH_DH_KEY] = dev_handle,
343	[UIH_INDEX_KEY] = fidx->index,	363	[UIH_INDEX_KEY] = fidx->index,
344	};	364	};
345		365
346	link_initialize(&fidx->uph_link);	366	link_initialize(&fidx->uph_link);
347	link_initialize(&fidx->uih_link);	367	link_initialize(&fidx->uih_link);
-		368	futex_initialize(&fidx->lock, 1);
348	fidx->dev_handle = dev_handle;	369	fidx->dev_handle = dev_handle;
349	fidx->pfc = pfc;	370	fidx->pfc = pfc;
350	fidx->pdi = pdi;	371	fidx->pdi = pdi;
351	fidx->nodep = NULL;	372	fidx->nodep = NULL;
352		373
353	hash_table_insert(&up_hash, pkey, &fidx->uph_link);	374	hash_table_insert(&up_hash, pkey, &fidx->uph_link);
354	hash_table_insert(&ui_hash, ikey, &fidx->uih_link);	375	hash_table_insert(&ui_hash, ikey, &fidx->uih_link);
355	}	376	}
-		377	futex_down(&fidx->lock);
-		378	futex_up(&used_futex);
356		379
357	return fidx;	380	return fidx;
358	}	381	}
359		382
360	fat_idx_t *	383	fat_idx_t *
Line 365...	Line 388...
365	unsigned long ikey[] = {	388	unsigned long ikey[] = {
366	[UIH_DH_KEY] = dev_handle,	389	[UIH_DH_KEY] = dev_handle,
367	[UIH_INDEX_KEY] = index,	390	[UIH_INDEX_KEY] = index,
368	};	391	};
369		392
-		393	futex_down(&used_futex);
370	l = hash_table_find(&ui_hash, ikey);	394	l = hash_table_find(&ui_hash, ikey);
371	if (l) {	395	if (l) {
372	fidx = hash_table_get_instance(l, fat_idx_t, uih_link);	396	fidx = hash_table_get_instance(l, fat_idx_t, uih_link);
-		397	futex_down(&fidx->lock);
373	}	398	}
-		399	futex_up(&used_futex);
374		400
375	return fidx;	401	return fidx;
376	}	402	}
377		403

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(root)/branches/tracing/uspace/srv/fs/fat/fat_idx.c @ 4692 – Rev 2925 → 3011