WebSVN – HelenOS – Diff – /branches/tracing/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;
 
static LIST_INITIALIZE(unused_head);
 
/**
 * 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);
    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;
    }
 
    /* 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;
            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);
        }
        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).
     */
    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;
 
    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;
    }
 
    /* should not happen */
    assert(0);
 
hit:
    if (u->next == index + 1) {
        /* The index can be returned directly to the counter. */
        u->next--;
        u->remaining++;
        return;
    } 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);
                return;
            }
            if (f->last == index - 1) {
                f->last++;
                if (lnk->next != &u->freed_head)
                    try_coalesce_intervals(lnk, lnk->next,
                        lnk);
                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);
                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);
    }
}
 
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,
    };
 
    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) {
            return NULL;
        }
        if (!fat_idx_alloc(dev_handle, &fidx->index)) {
            free(fidx);
            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);
        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);
    }
 
    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,
    };
 
    l = hash_table_find(&ui_hash, ikey);
    if (l) {
        fidx = hash_table_get_instance(l, fat_idx_t, uih_link);
    }
 
    return fidx;
}
 
 

Rev 2890	Rev 2925
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	static LIST_INITIALIZE(unused_head);	71	static LIST_INITIALIZE(unused_head);
72		72
73	/**	73	/**
74	* Global hash table of all used fat_idx_t structures.	74	* Global hash table of all used fat_idx_t structures.
75	* The index structures are hashed by the dev_handle, parent node's first	75	* The index structures are hashed by the dev_handle, parent node's first
76	* cluster and index within the parent directory.	76	* cluster and index within the parent directory.
77	*/	77	*/
78	static hash_table_t up_hash;	78	static hash_table_t up_hash;
79		79
80	#define UPH_BUCKETS_LOG 12	80	#define UPH_BUCKETS_LOG 12
81	#define UPH_BUCKETS (1 << UPH_BUCKETS_LOG)	81	#define UPH_BUCKETS (1 << UPH_BUCKETS_LOG)
82		82
83	#define UPH_DH_KEY 0	83	#define UPH_DH_KEY 0
84	#define UPH_PFC_KEY 1	84	#define UPH_PFC_KEY 1
85	#define UPH_PDI_KEY 2	85	#define UPH_PDI_KEY 2
86		86
87	static hash_index_t pos_hash(unsigned long key[])	87	static hash_index_t pos_hash(unsigned long key[])
88	{	88	{
89	dev_handle_t dev_handle = (dev_handle_t)key[UPH_DH_KEY];	89	dev_handle_t dev_handle = (dev_handle_t)key[UPH_DH_KEY];
90	fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];	90	fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];
91	unsigned pdi = (unsigned)key[UPH_PDI_KEY];	91	unsigned pdi = (unsigned)key[UPH_PDI_KEY];
92		92
93	hash_index_t h;	93	hash_index_t h;
94		94
95	/*	95	/*
96	* The least significant half of all bits are the least significant bits	96	* The least significant half of all bits are the least significant bits
97	* of the parent node's first cluster.	97	* of the parent node's first cluster.
98	*	98	*
99	* The least significant half of the most significant half of all bits	99	* The least significant half of the most significant half of all bits
100	* are the least significant bits of the node's dentry index within the	100	* are the least significant bits of the node's dentry index within the
101	* parent directory node.	101	* parent directory node.
102	*	102	*
103	* The most significant half of the most significant half of all bits	103	* The most significant half of the most significant half of all bits
104	* are the least significant bits of the device handle.	104	* are the least significant bits of the device handle.
105	*/	105	*/
106	h = pfc & ((1 << (UPH_BUCKETS_LOG / 2)) - 1);	106	h = pfc & ((1 << (UPH_BUCKETS_LOG / 2)) - 1);
107	h \|= (pdi & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<	107	h \|= (pdi & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<
108	(UPH_BUCKETS_LOG / 2);	108	(UPH_BUCKETS_LOG / 2);
109	h \|= (dev_handle & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<	109	h \|= (dev_handle & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<
110	(3 * (UPH_BUCKETS_LOG / 4));	110	(3 * (UPH_BUCKETS_LOG / 4));
111		111
112	return h;	112	return h;
113	}	113	}
114		114
115	static int pos_compare(unsigned long key[], hash_count_t keys, link_t *item)	115	static int pos_compare(unsigned long key[], hash_count_t keys, link_t *item)
116	{	116	{
117	dev_handle_t dev_handle = (dev_handle_t)key[UPH_DH_KEY];	117	dev_handle_t dev_handle = (dev_handle_t)key[UPH_DH_KEY];
118	fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];	118	fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];
119	unsigned pdi = (unsigned)key[UPH_PDI_KEY];	119	unsigned pdi = (unsigned)key[UPH_PDI_KEY];
120	fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uph_link);	120	fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uph_link);
121		121
122	return (dev_handle == fidx->dev_handle) && (pfc == fidx->pfc) &&	122	return (dev_handle == fidx->dev_handle) && (pfc == fidx->pfc) &&
123	(pdi == fidx->pdi);	123	(pdi == fidx->pdi);
124	}	124	}
125		125
126	static void pos_remove_callback(link_t *item)	126	static void pos_remove_callback(link_t *item)
127	{	127	{
128	/* nothing to do */	128	/* nothing to do */
129	}	129	}
130		130
131	static hash_table_operations_t uph_ops = {	131	static hash_table_operations_t uph_ops = {
132	.hash = pos_hash,	132	.hash = pos_hash,
133	.compare = pos_compare,	133	.compare = pos_compare,
134	.remove_callback = pos_remove_callback,	134	.remove_callback = pos_remove_callback,
135	};	135	};
136		136
137	/**	137	/**
138	* Global hash table of all used fat_idx_t structures.	138	* Global hash table of all used fat_idx_t structures.
139	* The index structures are hashed by the dev_handle and index.	139	* The index structures are hashed by the dev_handle and index.
140	*/	140	*/
141	static hash_table_t ui_hash;	141	static hash_table_t ui_hash;
142		142
143	#define UIH_BUCKETS_LOG 12	143	#define UIH_BUCKETS_LOG 12
144	#define UIH_BUCKETS (1 << UIH_BUCKETS_LOG)	144	#define UIH_BUCKETS (1 << UIH_BUCKETS_LOG)
145		145
146	#define UIH_DH_KEY 0	146	#define UIH_DH_KEY 0
147	#define UIH_INDEX_KEY 1	147	#define UIH_INDEX_KEY 1
148		148
149	static hash_index_t idx_hash(unsigned long key[])	149	static hash_index_t idx_hash(unsigned long key[])
150	{	150	{
151	dev_handle_t dev_handle = (dev_handle_t)key[UIH_DH_KEY];	151	dev_handle_t dev_handle = (dev_handle_t)key[UIH_DH_KEY];
152	fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY];	152	fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY];
153		153
154	hash_index_t h;	154	hash_index_t h;
155		155
156	h = dev_handle & ((1 << (UIH_BUCKETS_LOG / 2)) - 1);	156	h = dev_handle & ((1 << (UIH_BUCKETS_LOG / 2)) - 1);
157	h \|= (index & ((1 << (UIH_BUCKETS_LOG / 2)) - 1)) <<	157	h \|= (index & ((1 << (UIH_BUCKETS_LOG / 2)) - 1)) <<
158	(UIH_BUCKETS_LOG / 2);	158	(UIH_BUCKETS_LOG / 2);
159		159
160	return h;	160	return h;
161	}	161	}
162		162
163	static int idx_compare(unsigned long key[], hash_count_t keys, link_t *item)	163	static int idx_compare(unsigned long key[], hash_count_t keys, link_t *item)
164	{	164	{
165	dev_handle_t dev_handle = (dev_handle_t)key[UIH_DH_KEY];	165	dev_handle_t dev_handle = (dev_handle_t)key[UIH_DH_KEY];
166	fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY];	166	fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY];
167	fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uih_link);	167	fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uih_link);
168		168
169	return (dev_handle == fidx->dev_handle) && (index == fidx->index);	169	return (dev_handle == fidx->dev_handle) && (index == fidx->index);
170	}	170	}
171		171
172	static void idx_remove_callback(link_t *item)	172	static void idx_remove_callback(link_t *item)
173	{	173	{
174	/* nothing to do */	174	/* nothing to do */
175	}	175	}
176		176
177	static hash_table_operations_t uih_ops = {	177	static hash_table_operations_t uih_ops = {
178	.hash = idx_hash,	178	.hash = idx_hash,
179	.compare = idx_compare,	179	.compare = idx_compare,
180	.remove_callback = idx_remove_callback,	180	.remove_callback = idx_remove_callback,
181	};	181	};
182		182
183	/** Allocate a VFS index which is not currently in use. */	183	/** Allocate a VFS index which is not currently in use. */
184	static bool fat_idx_alloc(dev_handle_t dev_handle, fs_index_t *index)	184	static bool fat_idx_alloc(dev_handle_t dev_handle, fs_index_t *index)
185	{	185	{
186	link_t *l;	186	link_t *l;
187	unused_t *u;	187	unused_t *u;
188		188
189	assert(index);	189	assert(index);
190	for (l = unused_head.next; l != &unused_head; l = l->next) {	190	for (l = unused_head.next; l != &unused_head; l = l->next) {
191	u = list_get_instance(l, unused_t, link);	191	u = list_get_instance(l, unused_t, link);
192	if (u->dev_handle == dev_handle)	192	if (u->dev_handle == dev_handle)
193	goto hit;	193	goto hit;
194	}	194	}
195		195
196	/* dev_handle not found */	196	/* dev_handle not found */
197	return false;	197	return false;
198		198
199	hit:	199	hit:
200	if (list_empty(&u->freed_head)) {	200	if (list_empty(&u->freed_head)) {
201	if (u->remaining) {	201	if (u->remaining) {
202	/*	202	/*
203	* There are no freed indices, allocate one directly	203	* There are no freed indices, allocate one directly
204	* from the counter.	204	* from the counter.
205	*/	205	*/
206	*index = u->next++;	206	*index = u->next++;
207	--u->remaining;	207	--u->remaining;
208	return true;	208	return true;
209	}	209	}
210	} else {	210	} else {
211	/* There are some freed indices which we can reuse. */	211	/* There are some freed indices which we can reuse. */
212	freed_t *f = list_get_instance(u->freed_head.next, freed_t,	212	freed_t *f = list_get_instance(u->freed_head.next, freed_t,
213	link);	213	link);
214	*index = f->first;	214	*index = f->first;
215	if (f->first++ == f->last) {	215	if (f->first++ == f->last) {
216	/* Destroy the interval. */	216	/* Destroy the interval. */
217	list_remove(&f->link);	217	list_remove(&f->link);
218	free(f);	218	free(f);
219	}	219	}
220	return true;	220	return true;
221	}	221	}
222	/*	222	/*
223	* We ran out of indices, which is extremely unlikely with FAT16, but	223	* We ran out of indices, which is extremely unlikely with FAT16, but
224	* theoretically still possible (e.g. too many open unlinked nodes or	224	* theoretically still possible (e.g. too many open unlinked nodes or
225	* too many zero-sized nodes).	225	* too many zero-sized nodes).
226	*/	226	*/
227	return false;	227	return false;
228	}	228	}
229		229
230	/** If possible, coalesce two intervals of freed indices. */	230	/** If possible, coalesce two intervals of freed indices. */
231	static void try_coalesce_intervals(link_t l, link_t r, link_t *cur)	231	static void try_coalesce_intervals(link_t l, link_t r, link_t *cur)
232	{	232	{
233	freed_t *fl = list_get_instance(l, freed_t, link);	233	freed_t *fl = list_get_instance(l, freed_t, link);
234	freed_t *fr = list_get_instance(r, freed_t, link);	234	freed_t *fr = list_get_instance(r, freed_t, link);
235		235
236	if (fl->last + 1 == fr->first) {	236	if (fl->last + 1 == fr->first) {
237	if (cur == l) {	237	if (cur == l) {
238	fl->last = fr->last;	238	fl->last = fr->last;
239	list_remove(r);	239	list_remove(r);
240	free(r);	240	free(r);
241	} else {	241	} else {
242	fr->first = fl->first;	242	fr->first = fl->first;
243	list_remove(l);	243	list_remove(l);
244	free(l);	244	free(l);
245	}	245	}
246	}	246	}
247	}	247	}
248		248
249	/** Free a VFS index, which is no longer in use. */	249	/** Free a VFS index, which is no longer in use. */
250	static void fat_idx_free(dev_handle_t dev_handle, fs_index_t index)	250	static void fat_idx_free(dev_handle_t dev_handle, fs_index_t index)
251	{	251	{
252	link_t *l;	252	link_t *l;
253	unused_t *u;	253	unused_t *u;
254		254
255	for (l = unused_head.next; l != &unused_head; l = l->next) {	255	for (l = unused_head.next; l != &unused_head; l = l->next) {
256	u = list_get_instance(l, unused_t, link);	256	u = list_get_instance(l, unused_t, link);
257	if (u->dev_handle == dev_handle)	257	if (u->dev_handle == dev_handle)
258	goto hit;	258	goto hit;
259	}	259	}
260		260
261	/* should not happen */	261	/* should not happen */
262	assert(0);	262	assert(0);
263		263
264	hit:	264	hit:
265	if (u->next == index + 1) {	265	if (u->next == index + 1) {
266	/* The index can be returned directly to the counter. */	266	/* The index can be returned directly to the counter. */
267	u->next--;	267	u->next--;
268	u->remaining++;	268	u->remaining++;
269	return;	269	return;
270	} else {	270	} else {
271	/*	271	/*
272	* The index must be returned either to an existing freed	272	* The index must be returned either to an existing freed
273	* interval or a new interval must be created.	273	* interval or a new interval must be created.
274	*/	274	*/
275	link_t *lnk;	275	link_t *lnk;
276	freed_t *n;	276	freed_t *n;
277	for (lnk = u->freed_head.next; lnk != &u->freed_head;	277	for (lnk = u->freed_head.next; lnk != &u->freed_head;
278	lnk = lnk->next) {	278	lnk = lnk->next) {
279	freed_t *f = list_get_instance(lnk, freed_t, link);	279	freed_t *f = list_get_instance(lnk, freed_t, link);
280	if (f->first == index + 1) {	280	if (f->first == index + 1) {
281	f->first--;	281	f->first--;
282	if (lnk->prev != &u->freed_head)	282	if (lnk->prev != &u->freed_head)
283	try_coalesce_intervals(lnk->prev, lnk,	283	try_coalesce_intervals(lnk->prev, lnk,
284	lnk);	284	lnk);
285	return;	285	return;
286	}	286	}
287	if (f->last == index - 1) {	287	if (f->last == index - 1) {
288	f->last++;	288	f->last++;
289	if (lnk->next != &u->freed_head)	289	if (lnk->next != &u->freed_head)
290	try_coalesce_intervals(lnk, lnk->next,	290	try_coalesce_intervals(lnk, lnk->next,
291	lnk);	291	lnk);
292	return;	292	return;
293	}	293	}
294	if (index > f->first) {	294	if (index > f->first) {
295	n = malloc(sizeof(freed_t));	295	n = malloc(sizeof(freed_t));
296	/* TODO: sleep until allocation succeeds */	296	/* TODO: sleep until allocation succeeds */
297	assert(n);	297	assert(n);
298	link_initialize(&n->link);	298	link_initialize(&n->link);
299	n->first = index;	299	n->first = index;
300	n->last = index;	300	n->last = index;
301	list_insert_before(&n->link, lnk);	301	list_insert_before(&n->link, lnk);
302	return;	302	return;
303	}	303	}
304		304
305	}	305	}
306	/* The index will form the last interval. */	306	/* The index will form the last interval. */
307	n = malloc(sizeof(freed_t));	307	n = malloc(sizeof(freed_t));
308	/* TODO: sleep until allocation succeeds */	308	/* TODO: sleep until allocation succeeds */
309	assert(n);	309	assert(n);
310	link_initialize(&n->link);	310	link_initialize(&n->link);
311	n->first = index;	311	n->first = index;
312	n->last = index;	312	n->last = index;
313	list_append(&n->link, &u->freed_head);	313	list_append(&n->link, &u->freed_head);
314	}	314	}
315	}	315	}
316		316
317	fat_idx_t *	317	fat_idx_t *
318	fat_idx_get_by_pos(dev_handle_t dev_handle, fat_cluster_t pfc, unsigned pdi)	318	fat_idx_get_by_pos(dev_handle_t dev_handle, fat_cluster_t pfc, unsigned pdi)
319	{	319	{
320	fat_idx_t *fidx;	320	fat_idx_t *fidx;
321	link_t *l;	321	link_t *l;
322	unsigned long pkey[] = {	322	unsigned long pkey[] = {
323	[UPH_DH_KEY] = dev_handle,	323	[UPH_DH_KEY] = dev_handle,
324	[UPH_PFC_KEY] = pfc,	324	[UPH_PFC_KEY] = pfc,
325	[UPH_PDI_KEY] = pdi,	325	[UPH_PDI_KEY] = pdi,
326	};	326	};
327		327
328	l = hash_table_find(&up_hash, pkey);	328	l = hash_table_find(&up_hash, pkey);
329	if (l) {	329	if (l) {
330	fidx = hash_table_get_instance(l, fat_idx_t, uph_link);	330	fidx = hash_table_get_instance(l, fat_idx_t, uph_link);
331	} else {	331	} else {
332	fidx = (fat_idx_t *) malloc(sizeof(fat_idx_t));	332	fidx = (fat_idx_t *) malloc(sizeof(fat_idx_t));
333	if (!fidx) {	333	if (!fidx) {
334	return NULL;	334	return NULL;
335	}	335	}
336	if (!fat_idx_alloc(dev_handle, &fidx->index)) {	336	if (!fat_idx_alloc(dev_handle, &fidx->index)) {
337	free(fidx);	337	free(fidx);
338	return NULL;	338	return NULL;
339	}	339	}
340		340
341	unsigned long ikey[] = {	341	unsigned long ikey[] = {
342	[UIH_DH_KEY] = dev_handle,	342	[UIH_DH_KEY] = dev_handle,
343	[UIH_INDEX_KEY] = fidx->index,	343	[UIH_INDEX_KEY] = fidx->index,
344	};	344	};
345		345
346	link_initialize(&fidx->uph_link);	346	link_initialize(&fidx->uph_link);
347	link_initialize(&fidx->uih_link);	347	link_initialize(&fidx->uih_link);
348	fidx->dev_handle = dev_handle;	348	fidx->dev_handle = dev_handle;
349	fidx->pfc = pfc;	349	fidx->pfc = pfc;
350	fidx->pdi = pdi;	350	fidx->pdi = pdi;
351	fidx->nodep = NULL;	351	fidx->nodep = NULL;
352		352
353	hash_table_insert(&up_hash, pkey, &fidx->uph_link);	353	hash_table_insert(&up_hash, pkey, &fidx->uph_link);
354	hash_table_insert(&ui_hash, ikey, &fidx->uih_link);	354	hash_table_insert(&ui_hash, ikey, &fidx->uih_link);
355	}	355	}
356		356
357	return fidx;	357	return fidx;
358	}	358	}
359		359
360	fat_idx_t *	360	fat_idx_t *
361	fat_idx_get_by_index(dev_handle_t dev_handle, fs_index_t index)	361	fat_idx_get_by_index(dev_handle_t dev_handle, fs_index_t index)
362	{	362	{
363	fat_idx_t *fidx = NULL;	363	fat_idx_t *fidx = NULL;
364	link_t *l;	364	link_t *l;
365	unsigned long ikey[] = {	365	unsigned long ikey[] = {
366	[UIH_DH_KEY] = dev_handle,	366	[UIH_DH_KEY] = dev_handle,
367	[UIH_INDEX_KEY] = index,	367	[UIH_INDEX_KEY] = index,
368	};	368	};
369		369
370	l = hash_table_find(&ui_hash, ikey);	370	l = hash_table_find(&ui_hash, ikey);
371	if (l) {	371	if (l) {
372	fidx = hash_table_get_instance(l, fat_idx_t, uih_link);	372	fidx = hash_table_get_instance(l, fat_idx_t, uih_link);
373	}	373	}
374		374
375	return fidx;	375	return fidx;
376	}	376	}
377		377
378		378

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(root)/branches/tracing/uspace/srv/fs/fat/fat_idx.c @ 3030 – Rev 2890 → 2925