WebSVN – HelenOS – Diff – /branches/dd/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);
 
/** 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;
}
 
 

Rev 2951	Rev 3022
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	/** Futex protecting the up_hash and ui_hash. */	77	/** Futex protecting the up_hash and ui_hash. */
78	static futex_t used_futex = FUTEX_INITIALIZER;	78	static futex_t used_futex = FUTEX_INITIALIZER;
79		79
80	/**	80	/**
81	* Global hash table of all used fat_idx_t structures.	81	* Global hash table of all used fat_idx_t structures.
82	* 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
83	* cluster and index within the parent directory.	83	* cluster and index within the parent directory.
84	*/	84	*/
85	static hash_table_t up_hash;	85	static hash_table_t up_hash;
86		86
87	#define UPH_BUCKETS_LOG 12	87	#define UPH_BUCKETS_LOG 12
88	#define UPH_BUCKETS (1 << UPH_BUCKETS_LOG)	88	#define UPH_BUCKETS (1 << UPH_BUCKETS_LOG)
89		89
90	#define UPH_DH_KEY 0	90	#define UPH_DH_KEY 0
91	#define UPH_PFC_KEY 1	91	#define UPH_PFC_KEY 1
92	#define UPH_PDI_KEY 2	92	#define UPH_PDI_KEY 2
93		93
94	static hash_index_t pos_hash(unsigned long key[])	94	static hash_index_t pos_hash(unsigned long key[])
95	{	95	{
96	dev_handle_t dev_handle = (dev_handle_t)key[UPH_DH_KEY];	96	dev_handle_t dev_handle = (dev_handle_t)key[UPH_DH_KEY];
97	fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];	97	fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];
98	unsigned pdi = (unsigned)key[UPH_PDI_KEY];	98	unsigned pdi = (unsigned)key[UPH_PDI_KEY];
99		99
100	hash_index_t h;	100	hash_index_t h;
101		101
102	/*	102	/*
103	* The least significant half of all bits are the least significant bits	103	* The least significant half of all bits are the least significant bits
104	* of the parent node's first cluster.	104	* of the parent node's first cluster.
105	*	105	*
106	* The least significant half of the most significant half of all bits	106	* 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	107	* are the least significant bits of the node's dentry index within the
108	* parent directory node.	108	* parent directory node.
109	*	109	*
110	* The most significant half of the most significant half of all bits	110	* The most significant half of the most significant half of all bits
111	* are the least significant bits of the device handle.	111	* are the least significant bits of the device handle.
112	*/	112	*/
113	h = pfc & ((1 << (UPH_BUCKETS_LOG / 2)) - 1);	113	h = pfc & ((1 << (UPH_BUCKETS_LOG / 2)) - 1);
114	h \|= (pdi & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<	114	h \|= (pdi & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<
115	(UPH_BUCKETS_LOG / 2);	115	(UPH_BUCKETS_LOG / 2);
116	h \|= (dev_handle & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<	116	h \|= (dev_handle & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<
117	(3 * (UPH_BUCKETS_LOG / 4));	117	(3 * (UPH_BUCKETS_LOG / 4));
118		118
119	return h;	119	return h;
120	}	120	}
121		121
122	static int pos_compare(unsigned long key[], hash_count_t keys, link_t *item)	122	static int pos_compare(unsigned long key[], hash_count_t keys, link_t *item)
123	{	123	{
124	dev_handle_t dev_handle = (dev_handle_t)key[UPH_DH_KEY];	124	dev_handle_t dev_handle = (dev_handle_t)key[UPH_DH_KEY];
125	fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];	125	fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];
126	unsigned pdi = (unsigned)key[UPH_PDI_KEY];	126	unsigned pdi = (unsigned)key[UPH_PDI_KEY];
127	fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uph_link);	127	fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uph_link);
128		128
129	return (dev_handle == fidx->dev_handle) && (pfc == fidx->pfc) &&	129	return (dev_handle == fidx->dev_handle) && (pfc == fidx->pfc) &&
130	(pdi == fidx->pdi);	130	(pdi == fidx->pdi);
131	}	131	}
132		132
133	static void pos_remove_callback(link_t *item)	133	static void pos_remove_callback(link_t *item)
134	{	134	{
135	/* nothing to do */	135	/* nothing to do */
136	}	136	}
137		137
138	static hash_table_operations_t uph_ops = {	138	static hash_table_operations_t uph_ops = {
139	.hash = pos_hash,	139	.hash = pos_hash,
140	.compare = pos_compare,	140	.compare = pos_compare,
141	.remove_callback = pos_remove_callback,	141	.remove_callback = pos_remove_callback,
142	};	142	};
143		143
144	/**	144	/**
145	* Global hash table of all used fat_idx_t structures.	145	* Global hash table of all used fat_idx_t structures.
146	* The index structures are hashed by the dev_handle and index.	146	* The index structures are hashed by the dev_handle and index.
147	*/	147	*/
148	static hash_table_t ui_hash;	148	static hash_table_t ui_hash;
149		149
150	#define UIH_BUCKETS_LOG 12	150	#define UIH_BUCKETS_LOG 12
151	#define UIH_BUCKETS (1 << UIH_BUCKETS_LOG)	151	#define UIH_BUCKETS (1 << UIH_BUCKETS_LOG)
152		152
153	#define UIH_DH_KEY 0	153	#define UIH_DH_KEY 0
154	#define UIH_INDEX_KEY 1	154	#define UIH_INDEX_KEY 1
155		155
156	static hash_index_t idx_hash(unsigned long key[])	156	static hash_index_t idx_hash(unsigned long key[])
157	{	157	{
158	dev_handle_t dev_handle = (dev_handle_t)key[UIH_DH_KEY];	158	dev_handle_t dev_handle = (dev_handle_t)key[UIH_DH_KEY];
159	fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY];	159	fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY];
160		160
161	hash_index_t h;	161	hash_index_t h;
162		162
163	h = dev_handle & ((1 << (UIH_BUCKETS_LOG / 2)) - 1);	163	h = dev_handle & ((1 << (UIH_BUCKETS_LOG / 2)) - 1);
164	h \|= (index & ((1 << (UIH_BUCKETS_LOG / 2)) - 1)) <<	164	h \|= (index & ((1 << (UIH_BUCKETS_LOG / 2)) - 1)) <<
165	(UIH_BUCKETS_LOG / 2);	165	(UIH_BUCKETS_LOG / 2);
166		166
167	return h;	167	return h;
168	}	168	}
169		169
170	static int idx_compare(unsigned long key[], hash_count_t keys, link_t *item)	170	static int idx_compare(unsigned long key[], hash_count_t keys, link_t *item)
171	{	171	{
172	dev_handle_t dev_handle = (dev_handle_t)key[UIH_DH_KEY];	172	dev_handle_t dev_handle = (dev_handle_t)key[UIH_DH_KEY];
173	fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY];	173	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);	174	fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uih_link);
175		175
176	return (dev_handle == fidx->dev_handle) && (index == fidx->index);	176	return (dev_handle == fidx->dev_handle) && (index == fidx->index);
177	}	177	}
178		178
179	static void idx_remove_callback(link_t *item)	179	static void idx_remove_callback(link_t *item)
180	{	180	{
181	/* nothing to do */	181	/* nothing to do */
182	}	182	}
183		183
184	static hash_table_operations_t uih_ops = {	184	static hash_table_operations_t uih_ops = {
185	.hash = idx_hash,	185	.hash = idx_hash,
186	.compare = idx_compare,	186	.compare = idx_compare,
187	.remove_callback = idx_remove_callback,	187	.remove_callback = idx_remove_callback,
188	};	188	};
189		189
190	/** Allocate a VFS index which is not currently in use. */	190	/** 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)	191	static bool fat_idx_alloc(dev_handle_t dev_handle, fs_index_t *index)
192	{	192	{
193	link_t *l;	193	link_t *l;
194	unused_t *u;	194	unused_t *u;
195		195
196	assert(index);	196	assert(index);
197	futex_down(&unused_futex);	197	futex_down(&unused_futex);
198	for (l = unused_head.next; l != &unused_head; l = l->next) {	198	for (l = unused_head.next; l != &unused_head; l = l->next) {
199	u = list_get_instance(l, unused_t, link);	199	u = list_get_instance(l, unused_t, link);
200	if (u->dev_handle == dev_handle)	200	if (u->dev_handle == dev_handle)
201	goto hit;	201	goto hit;
202	}	202	}
203	futex_up(&unused_futex);	203	futex_up(&unused_futex);
204		204
205	/* dev_handle not found */	205	/* dev_handle not found */
206	return false;	206	return false;
207		207
208	hit:	208	hit:
209	if (list_empty(&u->freed_head)) {	209	if (list_empty(&u->freed_head)) {
210	if (u->remaining) {	210	if (u->remaining) {
211	/*	211	/*
212	* There are no freed indices, allocate one directly	212	* There are no freed indices, allocate one directly
213	* from the counter.	213	* from the counter.
214	*/	214	*/
215	*index = u->next++;	215	*index = u->next++;
216	--u->remaining;	216	--u->remaining;
217	futex_up(&unused_futex);	217	futex_up(&unused_futex);
218	return true;	218	return true;
219	}	219	}
220	} else {	220	} else {
221	/* There are some freed indices which we can reuse. */	221	/* There are some freed indices which we can reuse. */
222	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,
223	link);	223	link);
224	*index = f->first;	224	*index = f->first;
225	if (f->first++ == f->last) {	225	if (f->first++ == f->last) {
226	/* Destroy the interval. */	226	/* Destroy the interval. */
227	list_remove(&f->link);	227	list_remove(&f->link);
228	free(f);	228	free(f);
229	}	229	}
230	futex_up(&unused_futex);	230	futex_up(&unused_futex);
231	return true;	231	return true;
232	}	232	}
233	/*	233	/*
234	* 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
235	* theoretically still possible (e.g. too many open unlinked nodes or	235	* theoretically still possible (e.g. too many open unlinked nodes or
236	* too many zero-sized nodes).	236	* too many zero-sized nodes).
237	*/	237	*/
238	futex_up(&unused_futex);	238	futex_up(&unused_futex);
239	return false;	239	return false;
240	}	240	}
241		241
242	/** If possible, coalesce two intervals of freed indices. */	242	/** If possible, coalesce two intervals of freed indices. */
243	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)
244	{	244	{
245	freed_t *fl = list_get_instance(l, freed_t, link);	245	freed_t *fl = list_get_instance(l, freed_t, link);
246	freed_t *fr = list_get_instance(r, freed_t, link);	246	freed_t *fr = list_get_instance(r, freed_t, link);
247		247
248	if (fl->last + 1 == fr->first) {	248	if (fl->last + 1 == fr->first) {
249	if (cur == l) {	249	if (cur == l) {
250	fl->last = fr->last;	250	fl->last = fr->last;
251	list_remove(r);	251	list_remove(r);
252	free(r);	252	free(r);
253	} else {	253	} else {
254	fr->first = fl->first;	254	fr->first = fl->first;
255	list_remove(l);	255	list_remove(l);
256	free(l);	256	free(l);
257	}	257	}
258	}	258	}
259	}	259	}
260		260
261	/** Free a VFS index, which is no longer in use. */	261	/** 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)	262	static void fat_idx_free(dev_handle_t dev_handle, fs_index_t index)
263	{	263	{
264	link_t *l;	264	link_t *l;
265	unused_t *u;	265	unused_t *u;
266		266
267	futex_down(&unused_futex);	267	futex_down(&unused_futex);
268	for (l = unused_head.next; l != &unused_head; l = l->next) {	268	for (l = unused_head.next; l != &unused_head; l = l->next) {
269	u = list_get_instance(l, unused_t, link);	269	u = list_get_instance(l, unused_t, link);
270	if (u->dev_handle == dev_handle)	270	if (u->dev_handle == dev_handle)
271	goto hit;	271	goto hit;
272	}	272	}
273	futex_up(&unused_futex);	273	futex_up(&unused_futex);
274		274
275	/* should not happen */	275	/* should not happen */
276	assert(0);	276	assert(0);
277		277
278	hit:	278	hit:
279	if (u->next == index + 1) {	279	if (u->next == index + 1) {
280	/* The index can be returned directly to the counter. */	280	/* The index can be returned directly to the counter. */
281	u->next--;	281	u->next--;
282	u->remaining++;	282	u->remaining++;
283	} else {	283	} else {
284	/*	284	/*
285	* The index must be returned either to an existing freed	285	* The index must be returned either to an existing freed
286	* interval or a new interval must be created.	286	* interval or a new interval must be created.
287	*/	287	*/
288	link_t *lnk;	288	link_t *lnk;
289	freed_t *n;	289	freed_t *n;
290	for (lnk = u->freed_head.next; lnk != &u->freed_head;	290	for (lnk = u->freed_head.next; lnk != &u->freed_head;
291	lnk = lnk->next) {	291	lnk = lnk->next) {
292	freed_t *f = list_get_instance(lnk, freed_t, link);	292	freed_t *f = list_get_instance(lnk, freed_t, link);
293	if (f->first == index + 1) {	293	if (f->first == index + 1) {
294	f->first--;	294	f->first--;
295	if (lnk->prev != &u->freed_head)	295	if (lnk->prev != &u->freed_head)
296	try_coalesce_intervals(lnk->prev, lnk,	296	try_coalesce_intervals(lnk->prev, lnk,
297	lnk);	297	lnk);
298	futex_up(&unused_futex);	298	futex_up(&unused_futex);
299	return;	299	return;
300	}	300	}
301	if (f->last == index - 1) {	301	if (f->last == index - 1) {
302	f->last++;	302	f->last++;
303	if (lnk->next != &u->freed_head)	303	if (lnk->next != &u->freed_head)
304	try_coalesce_intervals(lnk, lnk->next,	304	try_coalesce_intervals(lnk, lnk->next,
305	lnk);	305	lnk);
306	futex_up(&unused_futex);	306	futex_up(&unused_futex);
307	return;	307	return;
308	}	308	}
309	if (index > f->first) {	309	if (index > f->first) {
310	n = malloc(sizeof(freed_t));	310	n = malloc(sizeof(freed_t));
311	/* TODO: sleep until allocation succeeds */	311	/* TODO: sleep until allocation succeeds */
312	assert(n);	312	assert(n);
313	link_initialize(&n->link);	313	link_initialize(&n->link);
314	n->first = index;	314	n->first = index;
315	n->last = index;	315	n->last = index;
316	list_insert_before(&n->link, lnk);	316	list_insert_before(&n->link, lnk);
317	futex_up(&unused_futex);	317	futex_up(&unused_futex);
318	return;	318	return;
319	}	319	}
320		320
321	}	321	}
322	/* The index will form the last interval. */	322	/* The index will form the last interval. */
323	n = malloc(sizeof(freed_t));	323	n = malloc(sizeof(freed_t));
324	/* TODO: sleep until allocation succeeds */	324	/* TODO: sleep until allocation succeeds */
325	assert(n);	325	assert(n);
326	link_initialize(&n->link);	326	link_initialize(&n->link);
327	n->first = index;	327	n->first = index;
328	n->last = index;	328	n->last = index;
329	list_append(&n->link, &u->freed_head);	329	list_append(&n->link, &u->freed_head);
330	}	330	}
331	futex_up(&unused_futex);	331	futex_up(&unused_futex);
332	}	332	}
333		333
334	fat_idx_t *	334	fat_idx_t *
335	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)
336	{	336	{
337	fat_idx_t *fidx;	337	fat_idx_t *fidx;
338	link_t *l;	338	link_t *l;
339	unsigned long pkey[] = {	339	unsigned long pkey[] = {
340	[UPH_DH_KEY] = dev_handle,	340	[UPH_DH_KEY] = dev_handle,
341	[UPH_PFC_KEY] = pfc,	341	[UPH_PFC_KEY] = pfc,
342	[UPH_PDI_KEY] = pdi,	342	[UPH_PDI_KEY] = pdi,
343	};	343	};
344		344
345	futex_down(&used_futex);	345	futex_down(&used_futex);
346	l = hash_table_find(&up_hash, pkey);	346	l = hash_table_find(&up_hash, pkey);
347	if (l) {	347	if (l) {
348	fidx = hash_table_get_instance(l, fat_idx_t, uph_link);	348	fidx = hash_table_get_instance(l, fat_idx_t, uph_link);
349	} else {	349	} else {
350	fidx = (fat_idx_t *) malloc(sizeof(fat_idx_t));	350	fidx = (fat_idx_t *) malloc(sizeof(fat_idx_t));
351	if (!fidx) {	351	if (!fidx) {
352	futex_up(&used_futex);	352	futex_up(&used_futex);
353	return NULL;	353	return NULL;
354	}	354	}
355	if (!fat_idx_alloc(dev_handle, &fidx->index)) {	355	if (!fat_idx_alloc(dev_handle, &fidx->index)) {
356	free(fidx);	356	free(fidx);
357	futex_up(&used_futex);	357	futex_up(&used_futex);
358	return NULL;	358	return NULL;
359	}	359	}
360		360
361	unsigned long ikey[] = {	361	unsigned long ikey[] = {
362	[UIH_DH_KEY] = dev_handle,	362	[UIH_DH_KEY] = dev_handle,
363	[UIH_INDEX_KEY] = fidx->index,	363	[UIH_INDEX_KEY] = fidx->index,
364	};	364	};
365		365
366	link_initialize(&fidx->uph_link);	366	link_initialize(&fidx->uph_link);
367	link_initialize(&fidx->uih_link);	367	link_initialize(&fidx->uih_link);
368	futex_initialize(&fidx->lock, 1);	368	futex_initialize(&fidx->lock, 1);
369	fidx->dev_handle = dev_handle;	369	fidx->dev_handle = dev_handle;
370	fidx->pfc = pfc;	370	fidx->pfc = pfc;
371	fidx->pdi = pdi;	371	fidx->pdi = pdi;
372	fidx->nodep = NULL;	372	fidx->nodep = NULL;
373		373
374	hash_table_insert(&up_hash, pkey, &fidx->uph_link);	374	hash_table_insert(&up_hash, pkey, &fidx->uph_link);
375	hash_table_insert(&ui_hash, ikey, &fidx->uih_link);	375	hash_table_insert(&ui_hash, ikey, &fidx->uih_link);
376	}	376	}
377	futex_down(&fidx->lock);	377	futex_down(&fidx->lock);
378	futex_up(&used_futex);	378	futex_up(&used_futex);
379		379
380	return fidx;	380	return fidx;
381	}	381	}
382		382
383	fat_idx_t *	383	fat_idx_t *
384	fat_idx_get_by_index(dev_handle_t dev_handle, fs_index_t index)	384	fat_idx_get_by_index(dev_handle_t dev_handle, fs_index_t index)
385	{	385	{
386	fat_idx_t *fidx = NULL;	386	fat_idx_t *fidx = NULL;
387	link_t *l;	387	link_t *l;
388	unsigned long ikey[] = {	388	unsigned long ikey[] = {
389	[UIH_DH_KEY] = dev_handle,	389	[UIH_DH_KEY] = dev_handle,
390	[UIH_INDEX_KEY] = index,	390	[UIH_INDEX_KEY] = index,
391	};	391	};
392		392
393	futex_down(&used_futex);	393	futex_down(&used_futex);
394	l = hash_table_find(&ui_hash, ikey);	394	l = hash_table_find(&ui_hash, ikey);
395	if (l) {	395	if (l) {
396	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);	397	futex_down(&fidx->lock);
398	}	398	}
399	futex_up(&used_futex);	399	futex_up(&used_futex);
400		400
401	return fidx;	401	return fidx;
402	}	402	}
403		403
404		404

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(root)/branches/dd/uspace/srv/fs/fat/fat_idx.c @ 4055 – Rev 2951 → 3022