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);
 
/** 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 2945	Rev 2951
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	*	-
79	* The locking strategy assumes that there will be at most one fibril for each	-
80	* dev_handle. Therefore it will be sufficient to hold the futex for shorter	-
81	* times (i.e. only during hash table operations as opposed to holding it the	-
82	* whole time between an unsuccessful find and the following insert). Should the	-
83	* assumption break, the locking strategy for this futex will have to be	-
84	* reconsidered.	-
85	*/	-
86	static futex_t used_futex = FUTEX_INITIALIZER;	78	static futex_t used_futex = FUTEX_INITIALIZER;
87		79
88	/**	80	/**
89	* Global hash table of all used fat_idx_t structures.	81	* Global hash table of all used fat_idx_t structures.
90	* 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
91	* cluster and index within the parent directory.	83	* cluster and index within the parent directory.
92	*/	84	*/
93	static hash_table_t up_hash;	85	static hash_table_t up_hash;
94		86
95	#define UPH_BUCKETS_LOG 12	87	#define UPH_BUCKETS_LOG 12
96	#define UPH_BUCKETS (1 << UPH_BUCKETS_LOG)	88	#define UPH_BUCKETS (1 << UPH_BUCKETS_LOG)
97		89
98	#define UPH_DH_KEY 0	90	#define UPH_DH_KEY 0
99	#define UPH_PFC_KEY 1	91	#define UPH_PFC_KEY 1
100	#define UPH_PDI_KEY 2	92	#define UPH_PDI_KEY 2
101		93
102	static hash_index_t pos_hash(unsigned long key[])	94	static hash_index_t pos_hash(unsigned long key[])
103	{	95	{
104	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];
105	fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];	97	fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];
106	unsigned pdi = (unsigned)key[UPH_PDI_KEY];	98	unsigned pdi = (unsigned)key[UPH_PDI_KEY];
107		99
108	hash_index_t h;	100	hash_index_t h;
109		101
110	/*	102	/*
111	* 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
112	* of the parent node's first cluster.	104	* of the parent node's first cluster.
113	*	105	*
114	* 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
115	* 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
116	* parent directory node.	108	* parent directory node.
117	*	109	*
118	* 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
119	* are the least significant bits of the device handle.	111	* are the least significant bits of the device handle.
120	*/	112	*/
121	h = pfc & ((1 << (UPH_BUCKETS_LOG / 2)) - 1);	113	h = pfc & ((1 << (UPH_BUCKETS_LOG / 2)) - 1);
122	h \|= (pdi & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<	114	h \|= (pdi & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<
123	(UPH_BUCKETS_LOG / 2);	115	(UPH_BUCKETS_LOG / 2);
124	h \|= (dev_handle & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<	116	h \|= (dev_handle & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<
125	(3 * (UPH_BUCKETS_LOG / 4));	117	(3 * (UPH_BUCKETS_LOG / 4));
126		118
127	return h;	119	return h;
128	}	120	}
129		121
130	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)
131	{	123	{
132	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];
133	fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];	125	fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];
134	unsigned pdi = (unsigned)key[UPH_PDI_KEY];	126	unsigned pdi = (unsigned)key[UPH_PDI_KEY];
135	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);
136		128
137	return (dev_handle == fidx->dev_handle) && (pfc == fidx->pfc) &&	129	return (dev_handle == fidx->dev_handle) && (pfc == fidx->pfc) &&
138	(pdi == fidx->pdi);	130	(pdi == fidx->pdi);
139	}	131	}
140		132
141	static void pos_remove_callback(link_t *item)	133	static void pos_remove_callback(link_t *item)
142	{	134	{
143	/* nothing to do */	135	/* nothing to do */
144	}	136	}
145		137
146	static hash_table_operations_t uph_ops = {	138	static hash_table_operations_t uph_ops = {
147	.hash = pos_hash,	139	.hash = pos_hash,
148	.compare = pos_compare,	140	.compare = pos_compare,
149	.remove_callback = pos_remove_callback,	141	.remove_callback = pos_remove_callback,
150	};	142	};
151		143
152	/**	144	/**
153	* Global hash table of all used fat_idx_t structures.	145	* Global hash table of all used fat_idx_t structures.
154	* The index structures are hashed by the dev_handle and index.	146	* The index structures are hashed by the dev_handle and index.
155	*/	147	*/
156	static hash_table_t ui_hash;	148	static hash_table_t ui_hash;
157		149
158	#define UIH_BUCKETS_LOG 12	150	#define UIH_BUCKETS_LOG 12
159	#define UIH_BUCKETS (1 << UIH_BUCKETS_LOG)	151	#define UIH_BUCKETS (1 << UIH_BUCKETS_LOG)
160		152
161	#define UIH_DH_KEY 0	153	#define UIH_DH_KEY 0
162	#define UIH_INDEX_KEY 1	154	#define UIH_INDEX_KEY 1
163		155
164	static hash_index_t idx_hash(unsigned long key[])	156	static hash_index_t idx_hash(unsigned long key[])
165	{	157	{
166	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];
167	fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY];	159	fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY];
168		160
169	hash_index_t h;	161	hash_index_t h;
170		162
171	h = dev_handle & ((1 << (UIH_BUCKETS_LOG / 2)) - 1);	163	h = dev_handle & ((1 << (UIH_BUCKETS_LOG / 2)) - 1);
172	h \|= (index & ((1 << (UIH_BUCKETS_LOG / 2)) - 1)) <<	164	h \|= (index & ((1 << (UIH_BUCKETS_LOG / 2)) - 1)) <<
173	(UIH_BUCKETS_LOG / 2);	165	(UIH_BUCKETS_LOG / 2);
174		166
175	return h;	167	return h;
176	}	168	}
177		169
178	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)
179	{	171	{
180	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];
181	fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY];	173	fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY];
182	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);
183		175
184	return (dev_handle == fidx->dev_handle) && (index == fidx->index);	176	return (dev_handle == fidx->dev_handle) && (index == fidx->index);
185	}	177	}
186		178
187	static void idx_remove_callback(link_t *item)	179	static void idx_remove_callback(link_t *item)
188	{	180	{
189	/* nothing to do */	181	/* nothing to do */
190	}	182	}
191		183
192	static hash_table_operations_t uih_ops = {	184	static hash_table_operations_t uih_ops = {
193	.hash = idx_hash,	185	.hash = idx_hash,
194	.compare = idx_compare,	186	.compare = idx_compare,
195	.remove_callback = idx_remove_callback,	187	.remove_callback = idx_remove_callback,
196	};	188	};
197		189
198	/** Allocate a VFS index which is not currently in use. */	190	/** Allocate a VFS index which is not currently in use. */
199	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)
200	{	192	{
201	link_t *l;	193	link_t *l;
202	unused_t *u;	194	unused_t *u;
203		195
204	assert(index);	196	assert(index);
205	futex_down(&unused_futex);	197	futex_down(&unused_futex);
206	for (l = unused_head.next; l != &unused_head; l = l->next) {	198	for (l = unused_head.next; l != &unused_head; l = l->next) {
207	u = list_get_instance(l, unused_t, link);	199	u = list_get_instance(l, unused_t, link);
208	if (u->dev_handle == dev_handle)	200	if (u->dev_handle == dev_handle)
209	goto hit;	201	goto hit;
210	}	202	}
211	futex_up(&unused_futex);	203	futex_up(&unused_futex);
212		204
213	/* dev_handle not found */	205	/* dev_handle not found */
214	return false;	206	return false;
215		207
216	hit:	208	hit:
217	if (list_empty(&u->freed_head)) {	209	if (list_empty(&u->freed_head)) {
218	if (u->remaining) {	210	if (u->remaining) {
219	/*	211	/*
220	* There are no freed indices, allocate one directly	212	* There are no freed indices, allocate one directly
221	* from the counter.	213	* from the counter.
222	*/	214	*/
223	*index = u->next++;	215	*index = u->next++;
224	--u->remaining;	216	--u->remaining;
225	futex_up(&unused_futex);	217	futex_up(&unused_futex);
226	return true;	218	return true;
227	}	219	}
228	} else {	220	} else {
229	/* There are some freed indices which we can reuse. */	221	/* There are some freed indices which we can reuse. */
230	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,
231	link);	223	link);
232	*index = f->first;	224	*index = f->first;
233	if (f->first++ == f->last) {	225	if (f->first++ == f->last) {
234	/* Destroy the interval. */	226	/* Destroy the interval. */
235	list_remove(&f->link);	227	list_remove(&f->link);
236	free(f);	228	free(f);
237	}	229	}
238	futex_up(&unused_futex);	230	futex_up(&unused_futex);
239	return true;	231	return true;
240	}	232	}
241	/*	233	/*
242	* 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
243	* theoretically still possible (e.g. too many open unlinked nodes or	235	* theoretically still possible (e.g. too many open unlinked nodes or
244	* too many zero-sized nodes).	236	* too many zero-sized nodes).
245	*/	237	*/
246	futex_up(&unused_futex);	238	futex_up(&unused_futex);
247	return false;	239	return false;
248	}	240	}
249		241
250	/** If possible, coalesce two intervals of freed indices. */	242	/** If possible, coalesce two intervals of freed indices. */
251	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)
252	{	244	{
253	freed_t *fl = list_get_instance(l, freed_t, link);	245	freed_t *fl = list_get_instance(l, freed_t, link);
254	freed_t *fr = list_get_instance(r, freed_t, link);	246	freed_t *fr = list_get_instance(r, freed_t, link);
255		247
256	if (fl->last + 1 == fr->first) {	248	if (fl->last + 1 == fr->first) {
257	if (cur == l) {	249	if (cur == l) {
258	fl->last = fr->last;	250	fl->last = fr->last;
259	list_remove(r);	251	list_remove(r);
260	free(r);	252	free(r);
261	} else {	253	} else {
262	fr->first = fl->first;	254	fr->first = fl->first;
263	list_remove(l);	255	list_remove(l);
264	free(l);	256	free(l);
265	}	257	}
266	}	258	}
267	}	259	}
268		260
269	/** Free a VFS index, which is no longer in use. */	261	/** Free a VFS index, which is no longer in use. */
270	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)
271	{	263	{
272	link_t *l;	264	link_t *l;
273	unused_t *u;	265	unused_t *u;
274		266
275	futex_down(&unused_futex);	267	futex_down(&unused_futex);
276	for (l = unused_head.next; l != &unused_head; l = l->next) {	268	for (l = unused_head.next; l != &unused_head; l = l->next) {
277	u = list_get_instance(l, unused_t, link);	269	u = list_get_instance(l, unused_t, link);
278	if (u->dev_handle == dev_handle)	270	if (u->dev_handle == dev_handle)
279	goto hit;	271	goto hit;
280	}	272	}
281	futex_up(&unused_futex);	273	futex_up(&unused_futex);
282		274
283	/* should not happen */	275	/* should not happen */
284	assert(0);	276	assert(0);
285		277
286	hit:	278	hit:
287	if (u->next == index + 1) {	279	if (u->next == index + 1) {
288	/* The index can be returned directly to the counter. */	280	/* The index can be returned directly to the counter. */
289	u->next--;	281	u->next--;
290	u->remaining++;	282	u->remaining++;
291	} else {	283	} else {
292	/*	284	/*
293	* The index must be returned either to an existing freed	285	* The index must be returned either to an existing freed
294	* interval or a new interval must be created.	286	* interval or a new interval must be created.
295	*/	287	*/
296	link_t *lnk;	288	link_t *lnk;
297	freed_t *n;	289	freed_t *n;
298	for (lnk = u->freed_head.next; lnk != &u->freed_head;	290	for (lnk = u->freed_head.next; lnk != &u->freed_head;
299	lnk = lnk->next) {	291	lnk = lnk->next) {
300	freed_t *f = list_get_instance(lnk, freed_t, link);	292	freed_t *f = list_get_instance(lnk, freed_t, link);
301	if (f->first == index + 1) {	293	if (f->first == index + 1) {
302	f->first--;	294	f->first--;
303	if (lnk->prev != &u->freed_head)	295	if (lnk->prev != &u->freed_head)
304	try_coalesce_intervals(lnk->prev, lnk,	296	try_coalesce_intervals(lnk->prev, lnk,
305	lnk);	297	lnk);
306	futex_up(&unused_futex);	298	futex_up(&unused_futex);
307	return;	299	return;
308	}	300	}
309	if (f->last == index - 1) {	301	if (f->last == index - 1) {
310	f->last++;	302	f->last++;
311	if (lnk->next != &u->freed_head)	303	if (lnk->next != &u->freed_head)
312	try_coalesce_intervals(lnk, lnk->next,	304	try_coalesce_intervals(lnk, lnk->next,
313	lnk);	305	lnk);
314	futex_up(&unused_futex);	306	futex_up(&unused_futex);
315	return;	307	return;
316	}	308	}
317	if (index > f->first) {	309	if (index > f->first) {
318	n = malloc(sizeof(freed_t));	310	n = malloc(sizeof(freed_t));
319	/* TODO: sleep until allocation succeeds */	311	/* TODO: sleep until allocation succeeds */
320	assert(n);	312	assert(n);
321	link_initialize(&n->link);	313	link_initialize(&n->link);
322	n->first = index;	314	n->first = index;
323	n->last = index;	315	n->last = index;
324	list_insert_before(&n->link, lnk);	316	list_insert_before(&n->link, lnk);
325	futex_up(&unused_futex);	317	futex_up(&unused_futex);
326	return;	318	return;
327	}	319	}
328		320
329	}	321	}
330	/* The index will form the last interval. */	322	/* The index will form the last interval. */
331	n = malloc(sizeof(freed_t));	323	n = malloc(sizeof(freed_t));
332	/* TODO: sleep until allocation succeeds */	324	/* TODO: sleep until allocation succeeds */
333	assert(n);	325	assert(n);
334	link_initialize(&n->link);	326	link_initialize(&n->link);
335	n->first = index;	327	n->first = index;
336	n->last = index;	328	n->last = index;
337	list_append(&n->link, &u->freed_head);	329	list_append(&n->link, &u->freed_head);
338	}	330	}
339	futex_up(&unused_futex);	331	futex_up(&unused_futex);
340	}	332	}
341		333
342	fat_idx_t *	334	fat_idx_t *
343	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)
344	{	336	{
345	fat_idx_t *fidx;	337	fat_idx_t *fidx;
346	link_t *l;	338	link_t *l;
347	unsigned long pkey[] = {	339	unsigned long pkey[] = {
348	[UPH_DH_KEY] = dev_handle,	340	[UPH_DH_KEY] = dev_handle,
349	[UPH_PFC_KEY] = pfc,	341	[UPH_PFC_KEY] = pfc,
350	[UPH_PDI_KEY] = pdi,	342	[UPH_PDI_KEY] = pdi,
351	};	343	};
352		344
353	futex_down(&used_futex);	345	futex_down(&used_futex);
354	l = hash_table_find(&up_hash, pkey);	346	l = hash_table_find(&up_hash, pkey);
355	futex_up(&used_futex);	-
356	if (l) {	347	if (l) {
357	fidx = hash_table_get_instance(l, fat_idx_t, uph_link);	348	fidx = hash_table_get_instance(l, fat_idx_t, uph_link);
358	} else {	349	} else {
359	fidx = (fat_idx_t *) malloc(sizeof(fat_idx_t));	350	fidx = (fat_idx_t *) malloc(sizeof(fat_idx_t));
360	if (!fidx) {	351	if (!fidx) {
-		352	futex_up(&used_futex);
361	return NULL;	353	return NULL;
362	}	354	}
363	if (!fat_idx_alloc(dev_handle, &fidx->index)) {	355	if (!fat_idx_alloc(dev_handle, &fidx->index)) {
364	free(fidx);	356	free(fidx);
-		357	futex_up(&used_futex);
365	return NULL;	358	return NULL;
366	}	359	}
367		360
368	unsigned long ikey[] = {	361	unsigned long ikey[] = {
369	[UIH_DH_KEY] = dev_handle,	362	[UIH_DH_KEY] = dev_handle,
370	[UIH_INDEX_KEY] = fidx->index,	363	[UIH_INDEX_KEY] = fidx->index,
371	};	364	};
372		365
373	link_initialize(&fidx->uph_link);	366	link_initialize(&fidx->uph_link);
374	link_initialize(&fidx->uih_link);	367	link_initialize(&fidx->uih_link);
-		368	futex_initialize(&fidx->lock, 1);
375	fidx->dev_handle = dev_handle;	369	fidx->dev_handle = dev_handle;
376	fidx->pfc = pfc;	370	fidx->pfc = pfc;
377	fidx->pdi = pdi;	371	fidx->pdi = pdi;
378	fidx->nodep = NULL;	372	fidx->nodep = NULL;
379		373
380	futex_down(&used_futex);	-
381	hash_table_insert(&up_hash, pkey, &fidx->uph_link);	374	hash_table_insert(&up_hash, pkey, &fidx->uph_link);
382	hash_table_insert(&ui_hash, ikey, &fidx->uih_link);	375	hash_table_insert(&ui_hash, ikey, &fidx->uih_link);
383	futex_up(&used_futex);	-
384	}	376	}
-		377	futex_down(&fidx->lock);
-		378	futex_up(&used_futex);
385		379
386	return fidx;	380	return fidx;
387	}	381	}
388		382
389	fat_idx_t *	383	fat_idx_t *
390	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)
391	{	385	{
392	fat_idx_t *fidx = NULL;	386	fat_idx_t *fidx = NULL;
393	link_t *l;	387	link_t *l;
394	unsigned long ikey[] = {	388	unsigned long ikey[] = {
395	[UIH_DH_KEY] = dev_handle,	389	[UIH_DH_KEY] = dev_handle,
396	[UIH_INDEX_KEY] = index,	390	[UIH_INDEX_KEY] = index,
397	};	391	};
398		392
399	futex_down(&used_futex);	393	futex_down(&used_futex);
400	l = hash_table_find(&ui_hash, ikey);	394	l = hash_table_find(&ui_hash, ikey);
401	futex_up(&used_futex);	-
402	if (l) {	395	if (l) {
403	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);
404	}	398	}
-		399	futex_up(&used_futex);
405		400
406	return fidx;	401	return fidx;
407	}	402	}
408		403
409		404

Subversion Repositories HelenOS

(root)/trunk/uspace/srv/fs/fat/fat_idx.c – Rev 2945 → 2951