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.
 *
 * The locking strategy assumes that there will be at most one fibril for each
 * dev_handle.  Therefore it will be sufficient to hold the futex for shorter
 * times (i.e. only during hash table operations as opposed to holding it the
 * whole time between an unsuccessful find and the following insert). Should the
 * assumption break, the locking strategy for this futex will have to be
 * reconsidered.
 */
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);
    futex_up(&used_futex);
    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;
 
        futex_down(&used_futex);
        hash_table_insert(&up_hash, pkey, &fidx->uph_link);
        hash_table_insert(&ui_hash, ikey, &fidx->uih_link);
        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);
    futex_up(&used_futex);
    if (l) {
        fidx = hash_table_get_instance(l, fat_idx_t, uih_link);
    }
 
    return fidx;
}
 
 

Rev 2944	Rev 2945
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.
-		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;
-		87
77	/**	88	/**
78	* Global hash table of all used fat_idx_t structures.	89	* Global hash table of all used fat_idx_t structures.
79	* The index structures are hashed by the dev_handle, parent node's first	90	* The index structures are hashed by the dev_handle, parent node's first
80	* cluster and index within the parent directory.	91	* cluster and index within the parent directory.
81	*/	92	*/
82	static hash_table_t up_hash;	93	static hash_table_t up_hash;
83		94
84	#define UPH_BUCKETS_LOG 12	95	#define UPH_BUCKETS_LOG 12
85	#define UPH_BUCKETS (1 << UPH_BUCKETS_LOG)	96	#define UPH_BUCKETS (1 << UPH_BUCKETS_LOG)
86		97
87	#define UPH_DH_KEY 0	98	#define UPH_DH_KEY 0
88	#define UPH_PFC_KEY 1	99	#define UPH_PFC_KEY 1
89	#define UPH_PDI_KEY 2	100	#define UPH_PDI_KEY 2
90		101
91	static hash_index_t pos_hash(unsigned long key[])	102	static hash_index_t pos_hash(unsigned long key[])
92	{	103	{
93	dev_handle_t dev_handle = (dev_handle_t)key[UPH_DH_KEY];	104	dev_handle_t dev_handle = (dev_handle_t)key[UPH_DH_KEY];
94	fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];	105	fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];
95	unsigned pdi = (unsigned)key[UPH_PDI_KEY];	106	unsigned pdi = (unsigned)key[UPH_PDI_KEY];
96		107
97	hash_index_t h;	108	hash_index_t h;
98		109
99	/*	110	/*
100	* The least significant half of all bits are the least significant bits	111	* The least significant half of all bits are the least significant bits
101	* of the parent node's first cluster.	112	* of the parent node's first cluster.
102	*	113	*
103	* The least significant half of the most significant half of all bits	114	* The least significant half of the most significant half of all bits
104	* are the least significant bits of the node's dentry index within the	115	* are the least significant bits of the node's dentry index within the
105	* parent directory node.	116	* parent directory node.
106	*	117	*
107	* The most significant half of the most significant half of all bits	118	* The most significant half of the most significant half of all bits
108	* are the least significant bits of the device handle.	119	* are the least significant bits of the device handle.
109	*/	120	*/
110	h = pfc & ((1 << (UPH_BUCKETS_LOG / 2)) - 1);	121	h = pfc & ((1 << (UPH_BUCKETS_LOG / 2)) - 1);
111	h \|= (pdi & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<	122	h \|= (pdi & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<
112	(UPH_BUCKETS_LOG / 2);	123	(UPH_BUCKETS_LOG / 2);
113	h \|= (dev_handle & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<	124	h \|= (dev_handle & ((1 << (UPH_BUCKETS_LOG / 4)) - 1)) <<
114	(3 * (UPH_BUCKETS_LOG / 4));	125	(3 * (UPH_BUCKETS_LOG / 4));
115		126
116	return h;	127	return h;
117	}	128	}
118		129
119	static int pos_compare(unsigned long key[], hash_count_t keys, link_t *item)	130	static int pos_compare(unsigned long key[], hash_count_t keys, link_t *item)
120	{	131	{
121	dev_handle_t dev_handle = (dev_handle_t)key[UPH_DH_KEY];	132	dev_handle_t dev_handle = (dev_handle_t)key[UPH_DH_KEY];
122	fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];	133	fat_cluster_t pfc = (fat_cluster_t)key[UPH_PFC_KEY];
123	unsigned pdi = (unsigned)key[UPH_PDI_KEY];	134	unsigned pdi = (unsigned)key[UPH_PDI_KEY];
124	fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uph_link);	135	fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uph_link);
125		136
126	return (dev_handle == fidx->dev_handle) && (pfc == fidx->pfc) &&	137	return (dev_handle == fidx->dev_handle) && (pfc == fidx->pfc) &&
127	(pdi == fidx->pdi);	138	(pdi == fidx->pdi);
128	}	139	}
129		140
130	static void pos_remove_callback(link_t *item)	141	static void pos_remove_callback(link_t *item)
131	{	142	{
132	/* nothing to do */	143	/* nothing to do */
133	}	144	}
134		145
135	static hash_table_operations_t uph_ops = {	146	static hash_table_operations_t uph_ops = {
136	.hash = pos_hash,	147	.hash = pos_hash,
137	.compare = pos_compare,	148	.compare = pos_compare,
138	.remove_callback = pos_remove_callback,	149	.remove_callback = pos_remove_callback,
139	};	150	};
140		151
141	/**	152	/**
142	* Global hash table of all used fat_idx_t structures.	153	* Global hash table of all used fat_idx_t structures.
143	* The index structures are hashed by the dev_handle and index.	154	* The index structures are hashed by the dev_handle and index.
144	*/	155	*/
145	static hash_table_t ui_hash;	156	static hash_table_t ui_hash;
146		157
147	#define UIH_BUCKETS_LOG 12	158	#define UIH_BUCKETS_LOG 12
148	#define UIH_BUCKETS (1 << UIH_BUCKETS_LOG)	159	#define UIH_BUCKETS (1 << UIH_BUCKETS_LOG)
149		160
150	#define UIH_DH_KEY 0	161	#define UIH_DH_KEY 0
151	#define UIH_INDEX_KEY 1	162	#define UIH_INDEX_KEY 1
152		163
153	static hash_index_t idx_hash(unsigned long key[])	164	static hash_index_t idx_hash(unsigned long key[])
154	{	165	{
155	dev_handle_t dev_handle = (dev_handle_t)key[UIH_DH_KEY];	166	dev_handle_t dev_handle = (dev_handle_t)key[UIH_DH_KEY];
156	fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY];	167	fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY];
157		168
158	hash_index_t h;	169	hash_index_t h;
159		170
160	h = dev_handle & ((1 << (UIH_BUCKETS_LOG / 2)) - 1);	171	h = dev_handle & ((1 << (UIH_BUCKETS_LOG / 2)) - 1);
161	h \|= (index & ((1 << (UIH_BUCKETS_LOG / 2)) - 1)) <<	172	h \|= (index & ((1 << (UIH_BUCKETS_LOG / 2)) - 1)) <<
162	(UIH_BUCKETS_LOG / 2);	173	(UIH_BUCKETS_LOG / 2);
163		174
164	return h;	175	return h;
165	}	176	}
166		177
167	static int idx_compare(unsigned long key[], hash_count_t keys, link_t *item)	178	static int idx_compare(unsigned long key[], hash_count_t keys, link_t *item)
168	{	179	{
169	dev_handle_t dev_handle = (dev_handle_t)key[UIH_DH_KEY];	180	dev_handle_t dev_handle = (dev_handle_t)key[UIH_DH_KEY];
170	fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY];	181	fs_index_t index = (fs_index_t)key[UIH_INDEX_KEY];
171	fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uih_link);	182	fat_idx_t *fidx = list_get_instance(item, fat_idx_t, uih_link);
172		183
173	return (dev_handle == fidx->dev_handle) && (index == fidx->index);	184	return (dev_handle == fidx->dev_handle) && (index == fidx->index);
174	}	185	}
175		186
176	static void idx_remove_callback(link_t *item)	187	static void idx_remove_callback(link_t *item)
177	{	188	{
178	/* nothing to do */	189	/* nothing to do */
179	}	190	}
180		191
181	static hash_table_operations_t uih_ops = {	192	static hash_table_operations_t uih_ops = {
182	.hash = idx_hash,	193	.hash = idx_hash,
183	.compare = idx_compare,	194	.compare = idx_compare,
184	.remove_callback = idx_remove_callback,	195	.remove_callback = idx_remove_callback,
185	};	196	};
186		197
187	/** Allocate a VFS index which is not currently in use. */	198	/** Allocate a VFS index which is not currently in use. */
188	static bool fat_idx_alloc(dev_handle_t dev_handle, fs_index_t *index)	199	static bool fat_idx_alloc(dev_handle_t dev_handle, fs_index_t *index)
189	{	200	{
190	link_t *l;	201	link_t *l;
191	unused_t *u;	202	unused_t *u;
192		203
193	assert(index);	204	assert(index);
194	futex_down(&unused_futex);	205	futex_down(&unused_futex);
195	for (l = unused_head.next; l != &unused_head; l = l->next) {	206	for (l = unused_head.next; l != &unused_head; l = l->next) {
196	u = list_get_instance(l, unused_t, link);	207	u = list_get_instance(l, unused_t, link);
197	if (u->dev_handle == dev_handle)	208	if (u->dev_handle == dev_handle)
198	goto hit;	209	goto hit;
199	}	210	}
200	futex_up(&unused_futex);	211	futex_up(&unused_futex);
201		212
202	/* dev_handle not found */	213	/* dev_handle not found */
203	return false;	214	return false;
204		215
205	hit:	216	hit:
206	if (list_empty(&u->freed_head)) {	217	if (list_empty(&u->freed_head)) {
207	if (u->remaining) {	218	if (u->remaining) {
208	/*	219	/*
209	* There are no freed indices, allocate one directly	220	* There are no freed indices, allocate one directly
210	* from the counter.	221	* from the counter.
211	*/	222	*/
212	*index = u->next++;	223	*index = u->next++;
213	--u->remaining;	224	--u->remaining;
214	futex_up(&unused_futex);	225	futex_up(&unused_futex);
215	return true;	226	return true;
216	}	227	}
217	} else {	228	} else {
218	/* There are some freed indices which we can reuse. */	229	/* There are some freed indices which we can reuse. */
219	freed_t *f = list_get_instance(u->freed_head.next, freed_t,	230	freed_t *f = list_get_instance(u->freed_head.next, freed_t,
220	link);	231	link);
221	*index = f->first;	232	*index = f->first;
222	if (f->first++ == f->last) {	233	if (f->first++ == f->last) {
223	/* Destroy the interval. */	234	/* Destroy the interval. */
224	list_remove(&f->link);	235	list_remove(&f->link);
225	free(f);	236	free(f);
226	}	237	}
227	futex_up(&unused_futex);	238	futex_up(&unused_futex);
228	return true;	239	return true;
229	}	240	}
230	/*	241	/*
231	* We ran out of indices, which is extremely unlikely with FAT16, but	242	* We ran out of indices, which is extremely unlikely with FAT16, but
232	* theoretically still possible (e.g. too many open unlinked nodes or	243	* theoretically still possible (e.g. too many open unlinked nodes or
233	* too many zero-sized nodes).	244	* too many zero-sized nodes).
234	*/	245	*/
235	futex_up(&unused_futex);	246	futex_up(&unused_futex);
236	return false;	247	return false;
237	}	248	}
238		249
239	/** If possible, coalesce two intervals of freed indices. */	250	/** If possible, coalesce two intervals of freed indices. */
240	static void try_coalesce_intervals(link_t l, link_t r, link_t *cur)	251	static void try_coalesce_intervals(link_t l, link_t r, link_t *cur)
241	{	252	{
242	freed_t *fl = list_get_instance(l, freed_t, link);	253	freed_t *fl = list_get_instance(l, freed_t, link);
243	freed_t *fr = list_get_instance(r, freed_t, link);	254	freed_t *fr = list_get_instance(r, freed_t, link);
244		255
245	if (fl->last + 1 == fr->first) {	256	if (fl->last + 1 == fr->first) {
246	if (cur == l) {	257	if (cur == l) {
247	fl->last = fr->last;	258	fl->last = fr->last;
248	list_remove(r);	259	list_remove(r);
249	free(r);	260	free(r);
250	} else {	261	} else {
251	fr->first = fl->first;	262	fr->first = fl->first;
252	list_remove(l);	263	list_remove(l);
253	free(l);	264	free(l);
254	}	265	}
255	}	266	}
256	}	267	}
257		268
258	/** Free a VFS index, which is no longer in use. */	269	/** Free a VFS index, which is no longer in use. */
259	static void fat_idx_free(dev_handle_t dev_handle, fs_index_t index)	270	static void fat_idx_free(dev_handle_t dev_handle, fs_index_t index)
260	{	271	{
261	link_t *l;	272	link_t *l;
262	unused_t *u;	273	unused_t *u;
263		274
264	futex_down(&unused_futex);	275	futex_down(&unused_futex);
265	for (l = unused_head.next; l != &unused_head; l = l->next) {	276	for (l = unused_head.next; l != &unused_head; l = l->next) {
266	u = list_get_instance(l, unused_t, link);	277	u = list_get_instance(l, unused_t, link);
267	if (u->dev_handle == dev_handle)	278	if (u->dev_handle == dev_handle)
268	goto hit;	279	goto hit;
269	}	280	}
270	futex_up(&unused_futex);	281	futex_up(&unused_futex);
271		282
272	/* should not happen */	283	/* should not happen */
273	assert(0);	284	assert(0);
274		285
275	hit:	286	hit:
276	if (u->next == index + 1) {	287	if (u->next == index + 1) {
277	/* The index can be returned directly to the counter. */	288	/* The index can be returned directly to the counter. */
278	u->next--;	289	u->next--;
279	u->remaining++;	290	u->remaining++;
280	} else {	291	} else {
281	/*	292	/*
282	* The index must be returned either to an existing freed	293	* The index must be returned either to an existing freed
283	* interval or a new interval must be created.	294	* interval or a new interval must be created.
284	*/	295	*/
285	link_t *lnk;	296	link_t *lnk;
286	freed_t *n;	297	freed_t *n;
287	for (lnk = u->freed_head.next; lnk != &u->freed_head;	298	for (lnk = u->freed_head.next; lnk != &u->freed_head;
288	lnk = lnk->next) {	299	lnk = lnk->next) {
289	freed_t *f = list_get_instance(lnk, freed_t, link);	300	freed_t *f = list_get_instance(lnk, freed_t, link);
290	if (f->first == index + 1) {	301	if (f->first == index + 1) {
291	f->first--;	302	f->first--;
292	if (lnk->prev != &u->freed_head)	303	if (lnk->prev != &u->freed_head)
293	try_coalesce_intervals(lnk->prev, lnk,	304	try_coalesce_intervals(lnk->prev, lnk,
294	lnk);	305	lnk);
295	futex_up(&unused_futex);	306	futex_up(&unused_futex);
296	return;	307	return;
297	}	308	}
298	if (f->last == index - 1) {	309	if (f->last == index - 1) {
299	f->last++;	310	f->last++;
300	if (lnk->next != &u->freed_head)	311	if (lnk->next != &u->freed_head)
301	try_coalesce_intervals(lnk, lnk->next,	312	try_coalesce_intervals(lnk, lnk->next,
302	lnk);	313	lnk);
303	futex_up(&unused_futex);	314	futex_up(&unused_futex);
304	return;	315	return;
305	}	316	}
306	if (index > f->first) {	317	if (index > f->first) {
307	n = malloc(sizeof(freed_t));	318	n = malloc(sizeof(freed_t));
308	/* TODO: sleep until allocation succeeds */	319	/* TODO: sleep until allocation succeeds */
309	assert(n);	320	assert(n);
310	link_initialize(&n->link);	321	link_initialize(&n->link);
311	n->first = index;	322	n->first = index;
312	n->last = index;	323	n->last = index;
313	list_insert_before(&n->link, lnk);	324	list_insert_before(&n->link, lnk);
314	futex_up(&unused_futex);	325	futex_up(&unused_futex);
315	return;	326	return;
316	}	327	}
317		328
318	}	329	}
319	/* The index will form the last interval. */	330	/* The index will form the last interval. */
320	n = malloc(sizeof(freed_t));	331	n = malloc(sizeof(freed_t));
321	/* TODO: sleep until allocation succeeds */	332	/* TODO: sleep until allocation succeeds */
322	assert(n);	333	assert(n);
323	link_initialize(&n->link);	334	link_initialize(&n->link);
324	n->first = index;	335	n->first = index;
325	n->last = index;	336	n->last = index;
326	list_append(&n->link, &u->freed_head);	337	list_append(&n->link, &u->freed_head);
327	}	338	}
328	futex_up(&unused_futex);	339	futex_up(&unused_futex);
329	}	340	}
330		341
331	fat_idx_t *	342	fat_idx_t *
332	fat_idx_get_by_pos(dev_handle_t dev_handle, fat_cluster_t pfc, unsigned pdi)	343	fat_idx_get_by_pos(dev_handle_t dev_handle, fat_cluster_t pfc, unsigned pdi)
333	{	344	{
334	fat_idx_t *fidx;	345	fat_idx_t *fidx;
335	link_t *l;	346	link_t *l;
336	unsigned long pkey[] = {	347	unsigned long pkey[] = {
337	[UPH_DH_KEY] = dev_handle,	348	[UPH_DH_KEY] = dev_handle,
338	[UPH_PFC_KEY] = pfc,	349	[UPH_PFC_KEY] = pfc,
339	[UPH_PDI_KEY] = pdi,	350	[UPH_PDI_KEY] = pdi,
340	};	351	};
341		352
-		353	futex_down(&used_futex);
342	l = hash_table_find(&up_hash, pkey);	354	l = hash_table_find(&up_hash, pkey);
-		355	futex_up(&used_futex);
343	if (l) {	356	if (l) {
344	fidx = hash_table_get_instance(l, fat_idx_t, uph_link);	357	fidx = hash_table_get_instance(l, fat_idx_t, uph_link);
345	} else {	358	} else {
346	fidx = (fat_idx_t *) malloc(sizeof(fat_idx_t));	359	fidx = (fat_idx_t *) malloc(sizeof(fat_idx_t));
347	if (!fidx) {	360	if (!fidx) {
348	return NULL;	361	return NULL;
349	}	362	}
350	if (!fat_idx_alloc(dev_handle, &fidx->index)) {	363	if (!fat_idx_alloc(dev_handle, &fidx->index)) {
351	free(fidx);	364	free(fidx);
352	return NULL;	365	return NULL;
353	}	366	}
354		367
355	unsigned long ikey[] = {	368	unsigned long ikey[] = {
356	[UIH_DH_KEY] = dev_handle,	369	[UIH_DH_KEY] = dev_handle,
357	[UIH_INDEX_KEY] = fidx->index,	370	[UIH_INDEX_KEY] = fidx->index,
358	};	371	};
359		372
360	link_initialize(&fidx->uph_link);	373	link_initialize(&fidx->uph_link);
361	link_initialize(&fidx->uih_link);	374	link_initialize(&fidx->uih_link);
362	fidx->dev_handle = dev_handle;	375	fidx->dev_handle = dev_handle;
363	fidx->pfc = pfc;	376	fidx->pfc = pfc;
364	fidx->pdi = pdi;	377	fidx->pdi = pdi;
365	fidx->nodep = NULL;	378	fidx->nodep = NULL;
366		379
-		380	futex_down(&used_futex);
367	hash_table_insert(&up_hash, pkey, &fidx->uph_link);	381	hash_table_insert(&up_hash, pkey, &fidx->uph_link);
368	hash_table_insert(&ui_hash, ikey, &fidx->uih_link);	382	hash_table_insert(&ui_hash, ikey, &fidx->uih_link);
-		383	futex_up(&used_futex);
369	}	384	}
370		385
371	return fidx;	386	return fidx;
372	}	387	}
373		388
374	fat_idx_t *	389	fat_idx_t *
375	fat_idx_get_by_index(dev_handle_t dev_handle, fs_index_t index)	390	fat_idx_get_by_index(dev_handle_t dev_handle, fs_index_t index)
376	{	391	{
377	fat_idx_t *fidx = NULL;	392	fat_idx_t *fidx = NULL;
378	link_t *l;	393	link_t *l;
379	unsigned long ikey[] = {	394	unsigned long ikey[] = {
380	[UIH_DH_KEY] = dev_handle,	395	[UIH_DH_KEY] = dev_handle,
381	[UIH_INDEX_KEY] = index,	396	[UIH_INDEX_KEY] = index,
382	};	397	};
383		398
-		399	futex_down(&used_futex);
384	l = hash_table_find(&ui_hash, ikey);	400	l = hash_table_find(&ui_hash, ikey);
-		401	futex_up(&used_futex);
385	if (l) {	402	if (l) {
386	fidx = hash_table_get_instance(l, fat_idx_t, uih_link);	403	fidx = hash_table_get_instance(l, fat_idx_t, uih_link);
387	}	404	}
388		405
389	return fidx;	406	return fidx;
390	}	407	}
391		408
392		409

Subversion Repositories HelenOS

(root)/trunk/uspace/srv/fs/fat/fat_idx.c – Rev 2944 → 2945