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


/*
 * Copyright (c) 2008 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
/** @addtogroup fs
 * @{
 */
 
/**
 * @file    fat_idx.c
 * @brief   Layer for translating FAT entities to VFS node indices.
 */
 
#include "fat.h"
#include "../../vfs/vfs.h"
#include <errno.h>
#include <string.h>
#include <libadt/hash_table.h>
#include <libadt/list.h>
#include <assert.h>
#include <futex.h>
 
/** Each instance of this type describes one interval of freed VFS indices. */
typedef struct {
    link_t      link;
    fs_index_t  first;
    fs_index_t  last;
} freed_t;
 
/**
 * Each instance of this type describes state of all VFS indices that
 * are currently unused.
 */
typedef struct {
    link_t      link;
    dev_handle_t    dev_handle;
 
    /** Next unassigned index. */
    fs_index_t  next;
    /** Number of remaining unassigned indices. */
    uint64_t    remaining;
 
    /** 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);
 
static void unused_initialize(unused_t *u, dev_handle_t dev_handle)
{
    link_initialize(&u->link);
    u->dev_handle = dev_handle;
    u->next = 0;
    u->remaining = ((uint64_t)((fs_index_t)-1)) + 1;
    list_initialize(&u->freed_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.
 */
static hash_table_t up_hash;
 
#define UPH_BUCKETS_LOG 12
#define UPH_BUCKETS (1 << UPH_BUCKETS_LOG)
 
#define UPH_DH_KEY  0
#define UPH_PFC_KEY 1
#define UPH_PDI_KEY 2
 
static hash_index_t pos_hash(unsigned long key[])
{
    dev_handle_t dev_handle = (dev_handle_t)key[UPH_DH_KEY];
    fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];
    unsigned pdi = (unsigned)key[UPH_PDI_KEY];
 
    hash_index_t h;
 
    /*
     * The least significant half of all bits are the least significant bits
     * of the parent node's first cluster.
     *
     * The least significant half of the most significant half of all bits
     * are the least significant bits of the node's dentry index within the
     * parent directory node.
     *
     * The most significant half of the most significant half of all bits
     * are the least significant bits of the device handle.
     */
    h = pfc & ((1 << (UPH_BUCKETS_LOG / 2)) - 1);
    h |= (pdi & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<
        (UPH_BUCKETS_LOG / 2);
    h |= (dev_handle & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<
        (3 * (UPH_BUCKETS_LOG / 4));
 
    return h;
}
 
static int pos_compare(unsigned long key[], hash_count_t keys, link_t *item)
{
    dev_handle_t dev_handle = (dev_handle_t)key[UPH_DH_KEY];
    fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];
    unsigned pdi = (unsigned)key[UPH_PDI_KEY];
    fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uph_link);
 
    return (dev_handle == fidx->dev_handle) && (pfc == fidx->pfc) &&
        (pdi == fidx->pdi);
}
 
static void pos_remove_callback(link_t *item)
{
    /* nothing to do */
}
 
static hash_table_operations_t uph_ops = {
    .hash = pos_hash,
    .compare = pos_compare,
    .remove_callback = pos_remove_callback,
};
 
/**
 * Global hash table of all used fat_idx_t structures.
 * The index structures are hashed by the dev_handle and index.
 */
static hash_table_t ui_hash;
 
#define UIH_BUCKETS_LOG 12
#define UIH_BUCKETS (1 << UIH_BUCKETS_LOG)
 
#define UIH_DH_KEY  0
#define UIH_INDEX_KEY   1
 
static hash_index_t idx_hash(unsigned long key[])
{
    dev_handle_t dev_handle = (dev_handle_t)key[UIH_DH_KEY];
    fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY];
 
    hash_index_t h;
 
    h = dev_handle & ((1 << (UIH_BUCKETS_LOG / 2)) - 1);
    h |= (index & ((1 << (UIH_BUCKETS_LOG / 2)) - 1)) <<
        (UIH_BUCKETS_LOG / 2);
 
    return h;
}
 
static int idx_compare(unsigned long key[], hash_count_t keys, link_t *item)
{
    dev_handle_t dev_handle = (dev_handle_t)key[UIH_DH_KEY];
    fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY];
    fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uih_link);
 
    return (dev_handle == fidx->dev_handle) && (index == fidx->index);
}
 
static void idx_remove_callback(link_t *item)
{
    /* nothing to do */
}
 
static hash_table_operations_t uih_ops = {
    .hash = idx_hash,
    .compare = idx_compare,
    .remove_callback = idx_remove_callback,
};
 
/** Allocate a VFS index which is not currently in use. */
static bool fat_idx_alloc(dev_handle_t dev_handle, fs_index_t *index)
{
    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)) {
        if (u->remaining) {
            /*
             * 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,
            link);
        *index = f->first;
        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)
{
    freed_t *fl = list_get_instance(l, freed_t, link);
    freed_t *fr = list_get_instance(r, freed_t, link);
 
    if (fl->last + 1 == fr->first) {
        if (cur == l) {
            fl->last = fr->last;
            list_remove(r);
            free(r);
        } else {
            fr->first = fl->first;
            list_remove(l);
            free(l);
        }
    }
}
 
/** Free a VFS index, which is no longer in use. */
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.
         */
        link_t *lnk;
        freed_t *n;
        for (lnk = u->freed_head.next; lnk != &u->freed_head;
            lnk = lnk->next) {
            freed_t *f = list_get_instance(lnk, freed_t, link);
            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. */
        n = malloc(sizeof(freed_t));
        /* TODO: sleep until allocation succeeds */
        assert(n);
        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)
{
    fat_idx_t *fidx;
    link_t *l;
    unsigned long pkey[] = {
        [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 *
fat_idx_get_by_index(dev_handle_t dev_handle, fs_index_t index)
{
    fat_idx_t *fidx = NULL;
    link_t *l;
    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;
}
 
int fat_idx_init(void)
{
    if (!hash_table_create(&up_hash, UPH_BUCKETS, 3, &uph_ops))
        return ENOMEM;
    if (!hash_table_create(&ui_hash, UIH_BUCKETS, 2, &uih_ops)) {
        hash_table_destroy(&up_hash);
        return ENOMEM;
    }
    return EOK;
}
 
void fat_idx_fini(void)
{
    /* We assume the hash tables are empty. */
    hash_table_destroy(&up_hash);
    hash_table_destroy(&ui_hash);
}
 
int fat_idx_init_by_dev_handle(dev_handle_t dev_handle)
{
    unused_t *u = (unused_t *) malloc(sizeof(unused_t));
    if (!u)
        return ENOMEM;
    unused_initialize(u, dev_handle);
    futex_down(&unused_futex);
    list_append(&u->link, &unused_head);
    futex_up(&unused_futex);
    return EOK;
}
 
void fat_idx_fini_by_dev_handle(dev_handle_t dev_handle)
{
    unused_t *u;
    link_t *l;
 
    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);
 
    assert(false);  /* should not happen */
 
hit:
    list_remove(&u->link);
    futex_up(&unused_futex);
 
    while (!list_empty(&u->freed_head)) {
        freed_t *f;
        f = list_get_instance(u->freed_head.next, freed_t, link);
        list_remove(&f->link);
        free(f);
    }
    free(u);
}
 
/**
 * @}
 */
 

Rev 2951	Rev 3110
1	/*	1	/*
2	* Copyright (c) 2008 Jakub Jermar	2	* Copyright (c) 2008 Jakub Jermar
3	* All rights reserved.	3	* All rights reserved.
4	*	4	*
5	* Redistribution and use in source and binary forms, with or without	5	* Redistribution and use in source and binary forms, with or without
6	* modification, are permitted provided that the following conditions	6	* modification, are permitted provided that the following conditions
7	* are met:	7	* are met:
8	*	8	*
9	* - Redistributions of source code must retain the above copyright	9	* - Redistributions of source code must retain the above copyright
10	* notice, this list of conditions and the following disclaimer.	10	* notice, this list of conditions and the following disclaimer.
11	* - Redistributions in binary form must reproduce the above copyright	11	* - Redistributions in binary form must reproduce the above copyright
12	* notice, this list of conditions and the following disclaimer in the	12	* notice, this list of conditions and the following disclaimer in the
13	* documentation and/or other materials provided with the distribution.	13	* documentation and/or other materials provided with the distribution.
14	* - The name of the author may not be used to endorse or promote products	14	* - The name of the author may not be used to endorse or promote products
15	* derived from this software without specific prior written permission.	15	* derived from this software without specific prior written permission.
16	*	16	*
17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR	17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES	18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.	19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,	20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT	21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,	22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY	23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT	24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF	25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.	26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27	*/	27	*/
28		28
29	/** @addtogroup fs	29	/** @addtogroup fs
30	* @{	30	* @{
31	*/	31	*/
32		32
33	/**	33	/**
34	* @file fat_idx.c	34	* @file fat_idx.c
35	* @brief Layer for translating FAT entities to VFS node indices.	35	* @brief Layer for translating FAT entities to VFS node indices.
36	*/	36	*/
37		37
38	#include "fat.h"	38	#include "fat.h"
39	#include "../../vfs/vfs.h"	39	#include "../../vfs/vfs.h"
40	#include <errno.h>	40	#include <errno.h>
41	#include <string.h>	41	#include <string.h>
42	#include <libadt/hash_table.h>	42	#include <libadt/hash_table.h>
43	#include <libadt/list.h>	43	#include <libadt/list.h>
44	#include <assert.h>	44	#include <assert.h>
45	#include <futex.h>	45	#include <futex.h>
46		46
47	/** Each instance of this type describes one interval of freed VFS indices. */	47	/** Each instance of this type describes one interval of freed VFS indices. */
48	typedef struct {	48	typedef struct {
49	link_t link;	49	link_t link;
50	fs_index_t first;	50	fs_index_t first;
51	fs_index_t last;	51	fs_index_t last;
52	} freed_t;	52	} freed_t;
53		53
54	/**	54	/**
55	* Each instance of this type describes state of all VFS indices that	55	* Each instance of this type describes state of all VFS indices that
56	* are currently unused.	56	* are currently unused.
57	*/	57	*/
58	typedef struct {	58	typedef struct {
59	link_t link;	59	link_t link;
60	dev_handle_t dev_handle;	60	dev_handle_t dev_handle;
61		61
62	/** Next unassigned index. */	62	/** Next unassigned index. */
63	fs_index_t next;	63	fs_index_t next;
64	/** Number of remaining unassigned indices. */	64	/** Number of remaining unassigned indices. */
65	uint64_t remaining;	65	uint64_t remaining;
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. */	71	/** Futex protecting the list of unused structures. */
72	static futex_t unused_futex = FUTEX_INITIALIZER;	72	static futex_t unused_futex = FUTEX_INITIALIZER;
73		73
74	/** List of unused structures. */	74	/** List of unused structures. */
75	static LIST_INITIALIZE(unused_head);	75	static LIST_INITIALIZE(unused_head);
76		76
-		77	static void unused_initialize(unused_t *u, dev_handle_t dev_handle)
-		78	{
-		79	link_initialize(&u->link);
-		80	u->dev_handle = dev_handle;
-		81	u->next = 0;
-		82	u->remaining = ((uint64_t)((fs_index_t)-1)) + 1;
-		83	list_initialize(&u->freed_head);
-		84	}
-		85
77	/** Futex protecting the up_hash and ui_hash. */	86	/** Futex protecting the up_hash and ui_hash. */
78	static futex_t used_futex = FUTEX_INITIALIZER;	87	static futex_t used_futex = FUTEX_INITIALIZER;
79		88
80	/**	89	/**
81	* Global hash table of all used fat_idx_t structures.	90	* Global hash table of all used fat_idx_t structures.
82	* The index structures are hashed by the dev_handle, parent node's first	91	* The index structures are hashed by the dev_handle, parent node's first
83	* cluster and index within the parent directory.	92	* cluster and index within the parent directory.
84	*/	93	*/
85	static hash_table_t up_hash;	94	static hash_table_t up_hash;
86		95
87	#define UPH_BUCKETS_LOG 12	96	#define UPH_BUCKETS_LOG 12
88	#define UPH_BUCKETS (1 << UPH_BUCKETS_LOG)	97	#define UPH_BUCKETS (1 << UPH_BUCKETS_LOG)
89		98
90	#define UPH_DH_KEY 0	99	#define UPH_DH_KEY 0
91	#define UPH_PFC_KEY 1	100	#define UPH_PFC_KEY 1
92	#define UPH_PDI_KEY 2	101	#define UPH_PDI_KEY 2
93		102
94	static hash_index_t pos_hash(unsigned long key[])	103	static hash_index_t pos_hash(unsigned long key[])
95	{	104	{
96	dev_handle_t dev_handle = (dev_handle_t)key[UPH_DH_KEY];	105	dev_handle_t dev_handle = (dev_handle_t)key[UPH_DH_KEY];
97	fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];	106	fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];
98	unsigned pdi = (unsigned)key[UPH_PDI_KEY];	107	unsigned pdi = (unsigned)key[UPH_PDI_KEY];
99		108
100	hash_index_t h;	109	hash_index_t h;
101		110
102	/*	111	/*
103	* The least significant half of all bits are the least significant bits	112	* The least significant half of all bits are the least significant bits
104	* of the parent node's first cluster.	113	* of the parent node's first cluster.
105	*	114	*
106	* The least significant half of the most significant half of all bits	115	* The least significant half of the most significant half of all bits
107	* are the least significant bits of the node's dentry index within the	116	* are the least significant bits of the node's dentry index within the
108	* parent directory node.	117	* parent directory node.
109	*	118	*
110	* The most significant half of the most significant half of all bits	119	* The most significant half of the most significant half of all bits
111	* are the least significant bits of the device handle.	120	* are the least significant bits of the device handle.
112	*/	121	*/
113	h = pfc & ((1 << (UPH_BUCKETS_LOG / 2)) - 1);	122	h = pfc & ((1 << (UPH_BUCKETS_LOG / 2)) - 1);
114	h \|= (pdi & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<	123	h \|= (pdi & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<
115	(UPH_BUCKETS_LOG / 2);	124	(UPH_BUCKETS_LOG / 2);
116	h \|= (dev_handle & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<	125	h \|= (dev_handle & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<
117	(3 * (UPH_BUCKETS_LOG / 4));	126	(3 * (UPH_BUCKETS_LOG / 4));
118		127
119	return h;	128	return h;
120	}	129	}
121		130
122	static int pos_compare(unsigned long key[], hash_count_t keys, link_t *item)	131	static int pos_compare(unsigned long key[], hash_count_t keys, link_t *item)
123	{	132	{
124	dev_handle_t dev_handle = (dev_handle_t)key[UPH_DH_KEY];	133	dev_handle_t dev_handle = (dev_handle_t)key[UPH_DH_KEY];
125	fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];	134	fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];
126	unsigned pdi = (unsigned)key[UPH_PDI_KEY];	135	unsigned pdi = (unsigned)key[UPH_PDI_KEY];
127	fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uph_link);	136	fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uph_link);
128		137
129	return (dev_handle == fidx->dev_handle) && (pfc == fidx->pfc) &&	138	return (dev_handle == fidx->dev_handle) && (pfc == fidx->pfc) &&
130	(pdi == fidx->pdi);	139	(pdi == fidx->pdi);
131	}	140	}
132		141
133	static void pos_remove_callback(link_t *item)	142	static void pos_remove_callback(link_t *item)
134	{	143	{
135	/* nothing to do */	144	/* nothing to do */
136	}	145	}
137		146
138	static hash_table_operations_t uph_ops = {	147	static hash_table_operations_t uph_ops = {
139	.hash = pos_hash,	148	.hash = pos_hash,
140	.compare = pos_compare,	149	.compare = pos_compare,
141	.remove_callback = pos_remove_callback,	150	.remove_callback = pos_remove_callback,
142	};	151	};
143		152
144	/**	153	/**
145	* Global hash table of all used fat_idx_t structures.	154	* Global hash table of all used fat_idx_t structures.
146	* The index structures are hashed by the dev_handle and index.	155	* The index structures are hashed by the dev_handle and index.
147	*/	156	*/
148	static hash_table_t ui_hash;	157	static hash_table_t ui_hash;
149		158
150	#define UIH_BUCKETS_LOG 12	159	#define UIH_BUCKETS_LOG 12
151	#define UIH_BUCKETS (1 << UIH_BUCKETS_LOG)	160	#define UIH_BUCKETS (1 << UIH_BUCKETS_LOG)
152		161
153	#define UIH_DH_KEY 0	162	#define UIH_DH_KEY 0
154	#define UIH_INDEX_KEY 1	163	#define UIH_INDEX_KEY 1
155		164
156	static hash_index_t idx_hash(unsigned long key[])	165	static hash_index_t idx_hash(unsigned long key[])
157	{	166	{
158	dev_handle_t dev_handle = (dev_handle_t)key[UIH_DH_KEY];	167	dev_handle_t dev_handle = (dev_handle_t)key[UIH_DH_KEY];
159	fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY];	168	fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY];
160		169
161	hash_index_t h;	170	hash_index_t h;
162		171
163	h = dev_handle & ((1 << (UIH_BUCKETS_LOG / 2)) - 1);	172	h = dev_handle & ((1 << (UIH_BUCKETS_LOG / 2)) - 1);
164	h \|= (index & ((1 << (UIH_BUCKETS_LOG / 2)) - 1)) <<	173	h \|= (index & ((1 << (UIH_BUCKETS_LOG / 2)) - 1)) <<
165	(UIH_BUCKETS_LOG / 2);	174	(UIH_BUCKETS_LOG / 2);
166		175
167	return h;	176	return h;
168	}	177	}
169		178
170	static int idx_compare(unsigned long key[], hash_count_t keys, link_t *item)	179	static int idx_compare(unsigned long key[], hash_count_t keys, link_t *item)
171	{	180	{
172	dev_handle_t dev_handle = (dev_handle_t)key[UIH_DH_KEY];	181	dev_handle_t dev_handle = (dev_handle_t)key[UIH_DH_KEY];
173	fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY];	182	fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY];
174	fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uih_link);	183	fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uih_link);
175		184
176	return (dev_handle == fidx->dev_handle) && (index == fidx->index);	185	return (dev_handle == fidx->dev_handle) && (index == fidx->index);
177	}	186	}
178		187
179	static void idx_remove_callback(link_t *item)	188	static void idx_remove_callback(link_t *item)
180	{	189	{
181	/* nothing to do */	190	/* nothing to do */
182	}	191	}
183		192
184	static hash_table_operations_t uih_ops = {	193	static hash_table_operations_t uih_ops = {
185	.hash = idx_hash,	194	.hash = idx_hash,
186	.compare = idx_compare,	195	.compare = idx_compare,
187	.remove_callback = idx_remove_callback,	196	.remove_callback = idx_remove_callback,
188	};	197	};
189		198
190	/** Allocate a VFS index which is not currently in use. */	199	/** Allocate a VFS index which is not currently in use. */
191	static bool fat_idx_alloc(dev_handle_t dev_handle, fs_index_t *index)	200	static bool fat_idx_alloc(dev_handle_t dev_handle, fs_index_t *index)
192	{	201	{
193	link_t *l;	202	link_t *l;
194	unused_t *u;	203	unused_t *u;
195		204
196	assert(index);	205	assert(index);
197	futex_down(&unused_futex);	206	futex_down(&unused_futex);
198	for (l = unused_head.next; l != &unused_head; l = l->next) {	207	for (l = unused_head.next; l != &unused_head; l = l->next) {
199	u = list_get_instance(l, unused_t, link);	208	u = list_get_instance(l, unused_t, link);
200	if (u->dev_handle == dev_handle)	209	if (u->dev_handle == dev_handle)
201	goto hit;	210	goto hit;
202	}	211	}
203	futex_up(&unused_futex);	212	futex_up(&unused_futex);
204		213
205	/* dev_handle not found */	214	/* dev_handle not found */
206	return false;	215	return false;
207		216
208	hit:	217	hit:
209	if (list_empty(&u->freed_head)) {	218	if (list_empty(&u->freed_head)) {
210	if (u->remaining) {	219	if (u->remaining) {
211	/*	220	/*
212	* There are no freed indices, allocate one directly	221	* There are no freed indices, allocate one directly
213	* from the counter.	222	* from the counter.
214	*/	223	*/
215	*index = u->next++;	224	*index = u->next++;
216	--u->remaining;	225	--u->remaining;
217	futex_up(&unused_futex);	226	futex_up(&unused_futex);
218	return true;	227	return true;
219	}	228	}
220	} else {	229	} else {
221	/* There are some freed indices which we can reuse. */	230	/* There are some freed indices which we can reuse. */
222	freed_t *f = list_get_instance(u->freed_head.next, freed_t,	231	freed_t *f = list_get_instance(u->freed_head.next, freed_t,
223	link);	232	link);
224	*index = f->first;	233	*index = f->first;
225	if (f->first++ == f->last) {	234	if (f->first++ == f->last) {
226	/* Destroy the interval. */	235	/* Destroy the interval. */
227	list_remove(&f->link);	236	list_remove(&f->link);
228	free(f);	237	free(f);
229	}	238	}
230	futex_up(&unused_futex);	239	futex_up(&unused_futex);
231	return true;	240	return true;
232	}	241	}
233	/*	242	/*
234	* We ran out of indices, which is extremely unlikely with FAT16, but	243	* We ran out of indices, which is extremely unlikely with FAT16, but
235	* theoretically still possible (e.g. too many open unlinked nodes or	244	* theoretically still possible (e.g. too many open unlinked nodes or
236	* too many zero-sized nodes).	245	* too many zero-sized nodes).
237	*/	246	*/
238	futex_up(&unused_futex);	247	futex_up(&unused_futex);
239	return false;	248	return false;
240	}	249	}
241		250
242	/** If possible, coalesce two intervals of freed indices. */	251	/** If possible, coalesce two intervals of freed indices. */
243	static void try_coalesce_intervals(link_t l, link_t r, link_t *cur)	252	static void try_coalesce_intervals(link_t l, link_t r, link_t *cur)
244	{	253	{
245	freed_t *fl = list_get_instance(l, freed_t, link);	254	freed_t *fl = list_get_instance(l, freed_t, link);
246	freed_t *fr = list_get_instance(r, freed_t, link);	255	freed_t *fr = list_get_instance(r, freed_t, link);
247		256
248	if (fl->last + 1 == fr->first) {	257	if (fl->last + 1 == fr->first) {
249	if (cur == l) {	258	if (cur == l) {
250	fl->last = fr->last;	259	fl->last = fr->last;
251	list_remove(r);	260	list_remove(r);
252	free(r);	261	free(r);
253	} else {	262	} else {
254	fr->first = fl->first;	263	fr->first = fl->first;
255	list_remove(l);	264	list_remove(l);
256	free(l);	265	free(l);
257	}	266	}
258	}	267	}
259	}	268	}
260		269
261	/** Free a VFS index, which is no longer in use. */	270	/** Free a VFS index, which is no longer in use. */
262	static void fat_idx_free(dev_handle_t dev_handle, fs_index_t index)	271	static void fat_idx_free(dev_handle_t dev_handle, fs_index_t index)
263	{	272	{
264	link_t *l;	273	link_t *l;
265	unused_t *u;	274	unused_t *u;
266		275
267	futex_down(&unused_futex);	276	futex_down(&unused_futex);
268	for (l = unused_head.next; l != &unused_head; l = l->next) {	277	for (l = unused_head.next; l != &unused_head; l = l->next) {
269	u = list_get_instance(l, unused_t, link);	278	u = list_get_instance(l, unused_t, link);
270	if (u->dev_handle == dev_handle)	279	if (u->dev_handle == dev_handle)
271	goto hit;	280	goto hit;
272	}	281	}
273	futex_up(&unused_futex);	282	futex_up(&unused_futex);
274		283
275	/* should not happen */	284	/* should not happen */
276	assert(0);	285	assert(0);
277		286
278	hit:	287	hit:
279	if (u->next == index + 1) {	288	if (u->next == index + 1) {
280	/* The index can be returned directly to the counter. */	289	/* The index can be returned directly to the counter. */
281	u->next--;	290	u->next--;
282	u->remaining++;	291	u->remaining++;
283	} else {	292	} else {
284	/*	293	/*
285	* The index must be returned either to an existing freed	294	* The index must be returned either to an existing freed
286	* interval or a new interval must be created.	295	* interval or a new interval must be created.
287	*/	296	*/
288	link_t *lnk;	297	link_t *lnk;
289	freed_t *n;	298	freed_t *n;
290	for (lnk = u->freed_head.next; lnk != &u->freed_head;	299	for (lnk = u->freed_head.next; lnk != &u->freed_head;
291	lnk = lnk->next) {	300	lnk = lnk->next) {
292	freed_t *f = list_get_instance(lnk, freed_t, link);	301	freed_t *f = list_get_instance(lnk, freed_t, link);
293	if (f->first == index + 1) {	302	if (f->first == index + 1) {
294	f->first--;	303	f->first--;
295	if (lnk->prev != &u->freed_head)	304	if (lnk->prev != &u->freed_head)
296	try_coalesce_intervals(lnk->prev, lnk,	305	try_coalesce_intervals(lnk->prev, lnk,
297	lnk);	306	lnk);
298	futex_up(&unused_futex);	307	futex_up(&unused_futex);
299	return;	308	return;
300	}	309	}
301	if (f->last == index - 1) {	310	if (f->last == index - 1) {
302	f->last++;	311	f->last++;
303	if (lnk->next != &u->freed_head)	312	if (lnk->next != &u->freed_head)
304	try_coalesce_intervals(lnk, lnk->next,	313	try_coalesce_intervals(lnk, lnk->next,
305	lnk);	314	lnk);
306	futex_up(&unused_futex);	315	futex_up(&unused_futex);
307	return;	316	return;
308	}	317	}
309	if (index > f->first) {	318	if (index > f->first) {
310	n = malloc(sizeof(freed_t));	319	n = malloc(sizeof(freed_t));
311	/* TODO: sleep until allocation succeeds */	320	/* TODO: sleep until allocation succeeds */
312	assert(n);	321	assert(n);
313	link_initialize(&n->link);	322	link_initialize(&n->link);
314	n->first = index;	323	n->first = index;
315	n->last = index;	324	n->last = index;
316	list_insert_before(&n->link, lnk);	325	list_insert_before(&n->link, lnk);
317	futex_up(&unused_futex);	326	futex_up(&unused_futex);
318	return;	327	return;
319	}	328	}
320		329
321	}	330	}
322	/* The index will form the last interval. */	331	/* The index will form the last interval. */
323	n = malloc(sizeof(freed_t));	332	n = malloc(sizeof(freed_t));
324	/* TODO: sleep until allocation succeeds */	333	/* TODO: sleep until allocation succeeds */
325	assert(n);	334	assert(n);
326	link_initialize(&n->link);	335	link_initialize(&n->link);
327	n->first = index;	336	n->first = index;
328	n->last = index;	337	n->last = index;
329	list_append(&n->link, &u->freed_head);	338	list_append(&n->link, &u->freed_head);
330	}	339	}
331	futex_up(&unused_futex);	340	futex_up(&unused_futex);
332	}	341	}
333		342
334	fat_idx_t *	343	fat_idx_t *
335	fat_idx_get_by_pos(dev_handle_t dev_handle, fat_cluster_t pfc, unsigned pdi)	344	fat_idx_get_by_pos(dev_handle_t dev_handle, fat_cluster_t pfc, unsigned pdi)
336	{	345	{
337	fat_idx_t *fidx;	346	fat_idx_t *fidx;
338	link_t *l;	347	link_t *l;
339	unsigned long pkey[] = {	348	unsigned long pkey[] = {
340	[UPH_DH_KEY] = dev_handle,	349	[UPH_DH_KEY] = dev_handle,
341	[UPH_PFC_KEY] = pfc,	350	[UPH_PFC_KEY] = pfc,
342	[UPH_PDI_KEY] = pdi,	351	[UPH_PDI_KEY] = pdi,
343	};	352	};
344		353
345	futex_down(&used_futex);	354	futex_down(&used_futex);
346	l = hash_table_find(&up_hash, pkey);	355	l = hash_table_find(&up_hash, pkey);
347	if (l) {	356	if (l) {
348	fidx = hash_table_get_instance(l, fat_idx_t, uph_link);	357	fidx = hash_table_get_instance(l, fat_idx_t, uph_link);
349	} else {	358	} else {
350	fidx = (fat_idx_t *) malloc(sizeof(fat_idx_t));	359	fidx = (fat_idx_t *) malloc(sizeof(fat_idx_t));
351	if (!fidx) {	360	if (!fidx) {
352	futex_up(&used_futex);	361	futex_up(&used_futex);
353	return NULL;	362	return NULL;
354	}	363	}
355	if (!fat_idx_alloc(dev_handle, &fidx->index)) {	364	if (!fat_idx_alloc(dev_handle, &fidx->index)) {
356	free(fidx);	365	free(fidx);
357	futex_up(&used_futex);	366	futex_up(&used_futex);
358	return NULL;	367	return NULL;
359	}	368	}
360		369
361	unsigned long ikey[] = {	370	unsigned long ikey[] = {
362	[UIH_DH_KEY] = dev_handle,	371	[UIH_DH_KEY] = dev_handle,
363	[UIH_INDEX_KEY] = fidx->index,	372	[UIH_INDEX_KEY] = fidx->index,
364	};	373	};
365		374
366	link_initialize(&fidx->uph_link);	375	link_initialize(&fidx->uph_link);
367	link_initialize(&fidx->uih_link);	376	link_initialize(&fidx->uih_link);
368	futex_initialize(&fidx->lock, 1);	377	futex_initialize(&fidx->lock, 1);
369	fidx->dev_handle = dev_handle;	378	fidx->dev_handle = dev_handle;
370	fidx->pfc = pfc;	379	fidx->pfc = pfc;
371	fidx->pdi = pdi;	380	fidx->pdi = pdi;
372	fidx->nodep = NULL;	381	fidx->nodep = NULL;
373		382
374	hash_table_insert(&up_hash, pkey, &fidx->uph_link);	383	hash_table_insert(&up_hash, pkey, &fidx->uph_link);
375	hash_table_insert(&ui_hash, ikey, &fidx->uih_link);	384	hash_table_insert(&ui_hash, ikey, &fidx->uih_link);
376	}	385	}
377	futex_down(&fidx->lock);	386	futex_down(&fidx->lock);
378	futex_up(&used_futex);	387	futex_up(&used_futex);
379		388
380	return fidx;	389	return fidx;
381	}	390	}
382		391
383	fat_idx_t *	392	fat_idx_t *
384	fat_idx_get_by_index(dev_handle_t dev_handle, fs_index_t index)	393	fat_idx_get_by_index(dev_handle_t dev_handle, fs_index_t index)
385	{	394	{
386	fat_idx_t *fidx = NULL;	395	fat_idx_t *fidx = NULL;
387	link_t *l;	396	link_t *l;
388	unsigned long ikey[] = {	397	unsigned long ikey[] = {
389	[UIH_DH_KEY] = dev_handle,	398	[UIH_DH_KEY] = dev_handle,
390	[UIH_INDEX_KEY] = index,	399	[UIH_INDEX_KEY] = index,
391	};	400	};
392		401
393	futex_down(&used_futex);	402	futex_down(&used_futex);
394	l = hash_table_find(&ui_hash, ikey);	403	l = hash_table_find(&ui_hash, ikey);
395	if (l) {	404	if (l) {
396	fidx = hash_table_get_instance(l, fat_idx_t, uih_link);	405	fidx = hash_table_get_instance(l, fat_idx_t, uih_link);
397	futex_down(&fidx->lock);	406	futex_down(&fidx->lock);
398	}	407	}
399	futex_up(&used_futex);	408	futex_up(&used_futex);
400		409
401	return fidx;	410	return fidx;
402	}	411	}
403		412
-		413	int fat_idx_init(void)
-		414	{
-		415	if (!hash_table_create(&up_hash, UPH_BUCKETS, 3, &uph_ops))
-		416	return ENOMEM;
-		417	if (!hash_table_create(&ui_hash, UIH_BUCKETS, 2, &uih_ops)) {
-		418	hash_table_destroy(&up_hash);
-		419	return ENOMEM;
-		420	}
-		421	return EOK;
-		422	}
-		423
-		424	void fat_idx_fini(void)
-		425	{
-		426	/* We assume the hash tables are empty. */
-		427	hash_table_destroy(&up_hash);
-		428	hash_table_destroy(&ui_hash);
-		429	}
-		430
-		431	int fat_idx_init_by_dev_handle(dev_handle_t dev_handle)
-		432	{
-		433	unused_t u = (unused_t ) malloc(sizeof(unused_t));
-		434	if (!u)
-		435	return ENOMEM;
-		436	unused_initialize(u, dev_handle);
-		437	futex_down(&unused_futex);
-		438	list_append(&u->link, &unused_head);
-		439	futex_up(&unused_futex);
-		440	return EOK;
-		441	}
-		442
-		443	void fat_idx_fini_by_dev_handle(dev_handle_t dev_handle)
-		444	{
-		445	unused_t *u;
-		446	link_t *l;
-		447
-		448	futex_down(&unused_futex);
-		449	for (l = unused_head.next; l != &unused_head; l = l->next) {
-		450	u = list_get_instance(l, unused_t, link);
-		451	if (u->dev_handle == dev_handle)
-		452	goto hit;
-		453	}
-		454	futex_up(&unused_futex);
-		455
-		456	assert(false); /* should not happen */
-		457
-		458	hit:
-		459	list_remove(&u->link);
-		460	futex_up(&unused_futex);
-		461
-		462	while (!list_empty(&u->freed_head)) {
-		463	freed_t *f;
-		464	f = list_get_instance(u->freed_head.next, freed_t, link);
-		465	list_remove(&f->link);
-		466	free(f);
-		467	}
-		468	free(u);
-		469	}
-		470
-		471	/**
-		472	* @}
-		473	*/
404		474

Subversion Repositories HelenOS

(root)/trunk/uspace/srv/fs/fat/fat_idx.c – Rev 2951 → 3110