WebSVN – HelenOS – Diff – /trunk/uspace/srv/fs/fat/fat_fat.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_fat.c
 * @brief   Functions that manipulate the File Allocation Tables.
 */
 
#include "fat_fat.h"
#include "fat_dentry.h"
#include "fat.h"
#include "../../vfs/vfs.h"
#include <libfs.h>
#include <libblock.h>
#include <errno.h>
#include <byteorder.h>
#include <align.h>
#include <assert.h>
#include <futex.h>
 
/**
 * The fat_alloc_lock futex protects all copies of the File Allocation Table
 * during allocation of clusters. The lock does not have to be held durring
 * deallocation of clusters.
 */  
static futex_t fat_alloc_lock = FUTEX_INITIALIZER;
 
/** Walk the cluster chain.
 *
 * @param bs        Buffer holding the boot sector for the file.
 * @param dev_handle    Device handle of the device with the file.
 * @param firstc    First cluster to start the walk with.
 * @param lastc     If non-NULL, output argument hodling the last cluster number visited.
 
 
 
 * @param max_clusters  Maximum number of clusters to visit.   
 *
 * @return      Number of clusters seen during the walk.
 */
uint16_t
fat_cluster_walk(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc,
    fat_cluster_t *lastc, uint16_t max_clusters)
{
    block_t *b;
    unsigned bps;
    unsigned rscnt;     /* block address of the first FAT */
    uint16_t clusters = 0;
    fat_cluster_t clst = firstc;
 
    bps = uint16_t_le2host(bs->bps);
    rscnt = uint16_t_le2host(bs->rscnt);
 
    if (firstc == FAT_CLST_RES0) {
        /* No space allocated to the file. */
        if (lastc)
            *lastc = firstc;
        return 0;
    }
 
 
 
 
 
    while (clst < FAT_CLST_LAST1 && clusters < max_clusters) {
        bn_t fsec;  /* sector offset relative to FAT1 */
        unsigned fidx;  /* FAT1 entry index */
 
        assert(clst >= FAT_CLST_FIRST);
        if (lastc)
            *lastc = clst;  /* remember the last cluster number */
        fsec = (clst * sizeof(fat_cluster_t)) / bps;
        fidx = clst % (bps / sizeof(fat_cluster_t));
        /* read FAT1 */
        b = block_get(dev_handle, rscnt + fsec);
        clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]);
        assert(clst != FAT_CLST_BAD);
        block_put(b);
        clusters++;
    }
 
    if (lastc && clst < FAT_CLST_LAST1)
        *lastc = clst;
 
    return clusters;
}
 
/** Read block from file located on a FAT file system.
 *
 * @param bs        Buffer holding the boot sector of the file system.
 * @param dev_handle    Device handle of the file system.
 * @param firstc    First cluster used by the file. Can be zero if the file
 *          is empty.
 * @param bn        Block number.
 *
 * @return      Block structure holding the requested block.
 */
block_t *
_fat_block_get(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc,
    bn_t bn)
{
    block_t *b;
    unsigned bps;
    unsigned rscnt;     /* block address of the first FAT */
    unsigned rde;
    unsigned rds;       /* root directory size */
    unsigned sf;
    unsigned ssa;       /* size of the system area */
    unsigned clusters, max_clusters;
    fat_cluster_t lastc, clst = firstc;
 
    bps = uint16_t_le2host(bs->bps);
    rscnt = uint16_t_le2host(bs->rscnt);
    rde = uint16_t_le2host(bs->root_ent_max);
    sf = uint16_t_le2host(bs->sec_per_fat);
 
    rds = (sizeof(fat_dentry_t) * rde) / bps;
    rds += ((sizeof(fat_dentry_t) * rde) % bps != 0);
    ssa = rscnt + bs->fatcnt * sf + rds;
 
    if (firstc == FAT_CLST_ROOT) {
        /* root directory special case */
        assert(bn < rds);
        b = block_get(dev_handle, rscnt + bs->fatcnt * sf + bn);
        return b;
    }
 
    max_clusters = bn / bs->spc;
    clusters = fat_cluster_walk(bs, dev_handle, firstc, &lastc,
        max_clusters);
    assert(clusters == max_clusters);
 
    b = block_get(dev_handle, ssa + (lastc - FAT_CLST_FIRST) * bs->spc +
        bn % bs->spc);
 
    return b;
}
 
 
/** Fill the gap between EOF and a new file position.
 *
 * @param bs        Buffer holding the boot sector for nodep.
 * @param nodep     FAT node with the gap.
 * @param mcl       First cluster in an independent cluster chain that will
 *          be later appended to the end of the node's own cluster
 *          chain. If pos is still in the last allocated cluster,
 *          this argument is ignored.
 * @param pos       Position in the last node block.
 */
void fat_fill_gap(fat_bs_t *bs, fat_node_t *nodep, fat_cluster_t mcl, off_t pos)
{
    uint16_t bps;
    unsigned spc;
    block_t *b;
    off_t o, boundary;
 
    bps = uint16_t_le2host(bs->bps);
    spc = bs->spc;
   
    boundary = ROUND_UP(nodep->size, bps * spc);
 
    /* zero out already allocated space */
    for (o = nodep->size - 1; o < pos && o < boundary;
        o = ALIGN_DOWN(o + bps, bps)) {
        b = fat_block_get(bs, nodep, o / bps);
        memset(b->data + o % bps, 0, bps - o % bps);
        b->dirty = true;        /* need to sync node */
        block_put(b);
    }
   
    if (o >= pos)
        return;
   
    /* zero out the initial part of the new cluster chain */
    for (o = boundary; o < pos; o += bps) {
        b = _fat_block_get(bs, nodep->idx->dev_handle, mcl,
            (o - boundary) / bps);
        memset(b->data, 0, min(bps, pos - o));
        b->dirty = true;        /* need to sync node */
        block_put(b);
    }
}
 
/** Mark cluster in one instance of FAT.
 *
 * @param bs        Buffer holding the boot sector for the file system.
 * @param dev_handle    Device handle for the file system.
 * @param fatno     Number of the FAT instance where to make the change.
 * @param clst      Cluster which is to be marked.
 * @param value     Value mark the cluster with.
 */
void
fat_mark_cluster(fat_bs_t *bs, dev_handle_t dev_handle, unsigned fatno,
    fat_cluster_t clst, fat_cluster_t value)
{
    block_t *b;
    uint16_t bps;
    uint16_t rscnt;
    uint16_t sf;
    fat_cluster_t *cp;
 
    bps = uint16_t_le2host(bs->bps);
    rscnt = uint16_t_le2host(bs->rscnt);
    sf = uint16_t_le2host(bs->sec_per_fat);
 
    assert(fatno < bs->fatcnt);
    b = block_get(dev_handle, rscnt + sf * fatno +
        (clst * sizeof(fat_cluster_t)) / bps);
    cp = (fat_cluster_t *)b->data + clst % (bps / sizeof(fat_cluster_t));
    *cp = host2uint16_t_le(value);
    b->dirty = true;        /* need to sync block */
    block_put(b);
}
 
/** Replay the allocatoin of clusters in all shadow instances of FAT.
 *
 * @param bs        Buffer holding the boot sector of the file system.
 * @param dev_handle    Device handle of the file system.
 * @param lifo      Chain of allocated clusters.
 * @param nclsts    Number of clusters in the lifo chain.
 */
void fat_alloc_shadow_clusters(fat_bs_t *bs, dev_handle_t dev_handle,
    fat_cluster_t *lifo, unsigned nclsts)
{
    uint8_t fatno;
    unsigned c;
 
    for (fatno = FAT1 + 1; fatno < bs->fatcnt; fatno++) {
        for (c = 0; c < nclsts; c++) {
            fat_mark_cluster(bs, dev_handle, fatno, lifo[c],
                c == 0 ? FAT_CLST_LAST1 : lifo[c - 1]);
        }
    }
}
 
/** Allocate clusters in FAT1.
 *
 * This function will attempt to allocate the requested number of clusters in
 * the first FAT instance.  The FAT will be altered so that the allocated
 * clusters form an independent chain (i.e. a chain which does not belong to any
 * file yet).
 *
 * @param bs        Buffer holding the boot sector of the file system.
 * @param dev_handle    Device handle of the file system.
 * @param nclsts    Number of clusters to allocate.
 * @param mcl       Output parameter where the first cluster in the chain
 *          will be returned.
 * @param lcl       Output parameter where the last cluster in the chain
 *          will be returned.
 *
 * @return      EOK on success, a negative error code otherwise.
 */
int
fat_alloc_clusters(fat_bs_t *bs, dev_handle_t dev_handle, unsigned nclsts,
    fat_cluster_t *mcl, fat_cluster_t *lcl)
{
    uint16_t bps;
    uint16_t rscnt;
    uint16_t sf;
    block_t *blk;
    fat_cluster_t *lifo;    /* stack for storing free cluster numbers */
    unsigned found = 0; /* top of the free cluster number stack */
    unsigned b, c, cl;
 
    lifo = (fat_cluster_t *) malloc(nclsts * sizeof(fat_cluster_t));
    if (lifo)
        return ENOMEM;
   
    bps = uint16_t_le2host(bs->bps);
    rscnt = uint16_t_le2host(bs->rscnt);
    sf = uint16_t_le2host(bs->sec_per_fat);
   
    /*
     * Search FAT1 for unused clusters.
     */
    futex_down(&fat_alloc_lock);
    for (b = 0, cl = 0; b < sf; blk++) {
        blk = block_get(dev_handle, rscnt + b);
        for (c = 0; c < bps / sizeof(fat_cluster_t); c++, cl++) {
            fat_cluster_t *clst = (fat_cluster_t *)blk->data + c;
            if (uint16_t_le2host(*clst) == FAT_CLST_RES0) {
                /*
                 * The cluster is free. Put it into our stack
                 * of found clusters and mark it as non-free.
                 */
                lifo[found] = cl;
                *clst = (found == 0) ?
                    host2uint16_t_le(FAT_CLST_LAST1) :
                    host2uint16_t_le(lifo[found - 1]);
                blk->dirty = true;  /* need to sync block */
                if (++found == nclsts) {
                    /* we are almost done */
                    block_put(blk);
                    /* update the shadow copies of FAT */
                    fat_alloc_shadow_clusters(bs,
                        dev_handle, lifo, nclsts);
                    *mcl = lifo[found - 1];
                    *lcl = lifo[0];
                    free(lifo);
                    futex_up(&fat_alloc_lock);
                    return EOK;
                }
            }
        }
        block_put(blk);
    }
    futex_up(&fat_alloc_lock);
 
    /*
     * We could not find enough clusters. Now we need to free the clusters
     * we have allocated so far.
     */
    while (found--) {
        fat_mark_cluster(bs, dev_handle, FAT1, lifo[found],
            FAT_CLST_RES0);
    }
   
    free(lifo);
    return ENOSPC;
}
 
/** Append a cluster chain to the last file cluster in all FATs.
 *
 * @param bs        Buffer holding boot sector of the file system.
 * @param nodep     Node representing the file.
 * @param mcl       First cluster of the cluster chain to append.
 */
void fat_append_clusters(fat_bs_t *bs, fat_node_t *nodep, fat_cluster_t mcl)
{
    dev_handle_t dev_handle = nodep->idx->dev_handle;
    fat_cluster_t lcl;
    uint8_t fatno;
 
    if (fat_cluster_walk(bs, nodep->idx->dev_handle, nodep->firstc, &lcl,
        (uint16_t) -1) == 0) {
        /* No clusters allocated to the node yet. */
        nodep->firstc = host2uint16_t_le(mcl);
        nodep->dirty = true;        /* need to sync node */
        return;
    }
 
    for (fatno = FAT1; fatno < bs->fatcnt; fatno++)
        fat_mark_cluster(bs, nodep->idx->dev_handle, fatno, lcl, mcl);
}
 
/**
 * @}
 */
 

Rev 3551	Rev 3571
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_fat.c	34	* @file fat_fat.c
35	* @brief Functions that manipulate the File Allocation Tables.	35	* @brief Functions that manipulate the File Allocation Tables.
36	*/	36	*/
37		37
38	#include "fat_fat.h"	38	#include "fat_fat.h"
39	#include "fat_dentry.h"	39	#include "fat_dentry.h"
40	#include "fat.h"	40	#include "fat.h"
41	#include "../../vfs/vfs.h"	41	#include "../../vfs/vfs.h"
42	#include <libfs.h>	42	#include <libfs.h>
43	#include <libblock.h>	43	#include <libblock.h>
44	#include <errno.h>	44	#include <errno.h>
45	#include <byteorder.h>	45	#include <byteorder.h>
46	#include <align.h>	46	#include <align.h>
47	#include <assert.h>	47	#include <assert.h>
48	#include <futex.h>	48	#include <futex.h>
49		49
50	/**	50	/**
51	* The fat_alloc_lock futex protects all copies of the File Allocation Table	51	* The fat_alloc_lock futex protects all copies of the File Allocation Table
52	* during allocation of clusters. The lock does not have to be held durring	52	* during allocation of clusters. The lock does not have to be held durring
53	* deallocation of clusters.	53	* deallocation of clusters.
54	*/	54	*/
55	static futex_t fat_alloc_lock = FUTEX_INITIALIZER;	55	static futex_t fat_alloc_lock = FUTEX_INITIALIZER;
56		56
57	/** Walk the cluster chain.	57	/** Walk the cluster chain.
58	*	58	*
59	* @param bs Buffer holding the boot sector for the file.	59	* @param bs Buffer holding the boot sector for the file.
60	* @param dev_handle Device handle of the device with the file.	60	* @param dev_handle Device handle of the device with the file.
61	* @param firstc First cluster to start the walk with.	61	* @param firstc First cluster to start the walk with.
62	* @param penult If non-NULL, output argument hodling the	62	* @param lastc If non-NULL, output argument hodling the last cluster number visited.
63	* the penultimate cluster visited.	-
64	* @param ult If non-NULL, output argument holding the	-
65	* ultimate cluster visited.	-
66	* @param max_clusters Maximum number of clusters to visit.	63	* @param max_clusters Maximum number of clusters to visit.
67	*	64	*
68	* @return Number of clusters seen during the walk.	65	* @return Number of clusters seen during the walk.
69	*/	66	*/
70	uint16_t	67	uint16_t
71	fat_cluster_walk(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc,	68	fat_cluster_walk(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc,
72	fat_cluster_t penult, fat_cluster_t ult, uint16_t max_clusters)	69	fat_cluster_t *lastc, uint16_t max_clusters)
73	{	70	{
74	block_t *b;	71	block_t *b;
75	unsigned bps;	72	unsigned bps;
76	unsigned rscnt; /* block address of the first FAT */	73	unsigned rscnt; /* block address of the first FAT */
77	uint16_t clusters = 0;	74	uint16_t clusters = 0;
78	fat_cluster_t clst = firstc;	75	fat_cluster_t clst = firstc;
79		76
80	bps = uint16_t_le2host(bs->bps);	77	bps = uint16_t_le2host(bs->bps);
81	rscnt = uint16_t_le2host(bs->rscnt);	78	rscnt = uint16_t_le2host(bs->rscnt);
82		79
83	if (firstc == FAT_CLST_RES0) {	80	if (firstc == FAT_CLST_RES0) {
84	/* No space allocated to the file. */	81	/* No space allocated to the file. */
85	if (ult)	82	if (lastc)
86	*ult = firstc;	83	*lastc = firstc;
87	return 0;	84	return 0;
88	}	85	}
89		86
90	/* At this point, the meaning of penult is not well-defined. */	-
91	if (penult)	-
92	*penult = FAT_CLST_RES0;	-
93		-
94	while (clst < FAT_CLST_LAST1 && clusters < max_clusters) {	87	while (clst < FAT_CLST_LAST1 && clusters < max_clusters) {
95	unsigned fsec; /* sector offset relative to FAT1 */	88	bn_t fsec; /* sector offset relative to FAT1 */
96	unsigned fidx; /* FAT1 entry index */	89	unsigned fidx; /* FAT1 entry index */
97		90
98	assert(clst >= FAT_CLST_FIRST);	91	assert(clst >= FAT_CLST_FIRST);
99	if (penult)	92	if (lastc)
100	penult = clst; / remember the penultimate cluster */	93	lastc = clst; / remember the last cluster number */
101	fsec = (clst * sizeof(fat_cluster_t)) / bps;	94	fsec = (clst * sizeof(fat_cluster_t)) / bps;
102	fidx = clst % (bps / sizeof(fat_cluster_t));	95	fidx = clst % (bps / sizeof(fat_cluster_t));
103	/* read FAT1 */	96	/* read FAT1 */
104	b = block_get(dev_handle, rscnt + fsec);	97	b = block_get(dev_handle, rscnt + fsec);
105	clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]);	98	clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]);
106	assert(clst != FAT_CLST_BAD);	99	assert(clst != FAT_CLST_BAD);
107	block_put(b);	100	block_put(b);
108	clusters++;	101	clusters++;
109	}	102	}
110		103
111	if (ult)	104	if (lastc && clst < FAT_CLST_LAST1)
112	*ult = clst;	105	*lastc = clst;
113		106
114	return clusters;	107	return clusters;
115	}	108	}
116		109
117	/** Read block from file located on a FAT file system.	110	/** Read block from file located on a FAT file system.
118	*	111	*
119	* @param bs Buffer holding the boot sector of the file system.	112	* @param bs Buffer holding the boot sector of the file system.
120	* @param dev_handle Device handle of the file system.	113	* @param dev_handle Device handle of the file system.
121	* @param firstc First cluster used by the file. Can be zero if the file	114	* @param firstc First cluster used by the file. Can be zero if the file
122	* is empty.	115	* is empty.
123	* @param offset Offset in blocks.	116	* @param bn Block number.
124	*	117	*
125	* @return Block structure holding the requested block.	118	* @return Block structure holding the requested block.
126	*/	119	*/
127	block_t *	120	block_t *
128	_fat_block_get(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc,	121	_fat_block_get(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc,
129	off_t offset)	122	bn_t bn)
130	{	123	{
131	block_t *b;	124	block_t *b;
132	unsigned bps;	125	unsigned bps;
133	unsigned rscnt; /* block address of the first FAT */	126	unsigned rscnt; /* block address of the first FAT */
134	unsigned rde;	127	unsigned rde;
135	unsigned rds; /* root directory size */	128	unsigned rds; /* root directory size */
136	unsigned sf;	129	unsigned sf;
137	unsigned ssa; /* size of the system area */	130	unsigned ssa; /* size of the system area */
138	unsigned clusters, max_clusters;	131	unsigned clusters, max_clusters;
139	fat_cluster_t lastc, clst = firstc;	132	fat_cluster_t lastc, clst = firstc;
140		133
141	bps = uint16_t_le2host(bs->bps);	134	bps = uint16_t_le2host(bs->bps);
142	rscnt = uint16_t_le2host(bs->rscnt);	135	rscnt = uint16_t_le2host(bs->rscnt);
143	rde = uint16_t_le2host(bs->root_ent_max);	136	rde = uint16_t_le2host(bs->root_ent_max);
144	sf = uint16_t_le2host(bs->sec_per_fat);	137	sf = uint16_t_le2host(bs->sec_per_fat);
145		138
146	rds = (sizeof(fat_dentry_t) * rde) / bps;	139	rds = (sizeof(fat_dentry_t) * rde) / bps;
147	rds += ((sizeof(fat_dentry_t) * rde) % bps != 0);	140	rds += ((sizeof(fat_dentry_t) * rde) % bps != 0);
148	ssa = rscnt + bs->fatcnt * sf + rds;	141	ssa = rscnt + bs->fatcnt * sf + rds;
149		142
150	if (firstc == FAT_CLST_ROOT) {	143	if (firstc == FAT_CLST_ROOT) {
151	/* root directory special case */	144	/* root directory special case */
152	assert(offset < rds);	145	assert(bn < rds);
153	b = block_get(dev_handle, rscnt + bs->fatcnt * sf + offset);	146	b = block_get(dev_handle, rscnt + bs->fatcnt * sf + bn);
154	return b;	147	return b;
155	}	148	}
156		149
157	max_clusters = offset / bs->spc;	150	max_clusters = bn / bs->spc;
158	clusters = fat_cluster_walk(bs, dev_handle, firstc, NULL, &lastc,	151	clusters = fat_cluster_walk(bs, dev_handle, firstc, &lastc,
159	max_clusters);	152	max_clusters);
160	assert(clusters == max_clusters);	153	assert(clusters == max_clusters);
161		154
162	b = block_get(dev_handle, ssa + (lastc - FAT_CLST_FIRST) * bs->spc +	155	b = block_get(dev_handle, ssa + (lastc - FAT_CLST_FIRST) * bs->spc +
163	offset % bs->spc);	156	bn % bs->spc);
164		157
165	return b;	158	return b;
166	}	159	}
167		160
168		161
169	/** Fill the gap between EOF and a new file position.	162	/** Fill the gap between EOF and a new file position.
170	*	163	*
171	* @param bs Buffer holding the boot sector for nodep.	164	* @param bs Buffer holding the boot sector for nodep.
172	* @param nodep FAT node with the gap.	165	* @param nodep FAT node with the gap.
173	* @param mcl First cluster in an independent cluster chain that will	166	* @param mcl First cluster in an independent cluster chain that will
174	* be later appended to the end of the node's own cluster	167	* be later appended to the end of the node's own cluster
175	* chain. If pos is still in the last allocated cluster,	168	* chain. If pos is still in the last allocated cluster,
176	* this argument is ignored.	169	* this argument is ignored.
177	* @param pos Position in the last node block.	170	* @param pos Position in the last node block.
178	*/	171	*/
179	void fat_fill_gap(fat_bs_t bs, fat_node_t nodep, fat_cluster_t mcl, off_t pos)	172	void fat_fill_gap(fat_bs_t bs, fat_node_t nodep, fat_cluster_t mcl, off_t pos)
180	{	173	{
181	uint16_t bps;	174	uint16_t bps;
182	unsigned spc;	175	unsigned spc;
183	block_t *b;	176	block_t *b;
184	off_t o, boundary;	177	off_t o, boundary;
185		178
186	bps = uint16_t_le2host(bs->bps);	179	bps = uint16_t_le2host(bs->bps);
187	spc = bs->spc;	180	spc = bs->spc;
188		181
189	boundary = ROUND_UP(nodep->size, bps * spc);	182	boundary = ROUND_UP(nodep->size, bps * spc);
190		183
191	/* zero out already allocated space */	184	/* zero out already allocated space */
192	for (o = nodep->size - 1; o < pos && o < boundary;	185	for (o = nodep->size - 1; o < pos && o < boundary;
193	o = ALIGN_DOWN(o + bps, bps)) {	186	o = ALIGN_DOWN(o + bps, bps)) {
194	b = fat_block_get(bs, nodep, o / bps);	187	b = fat_block_get(bs, nodep, o / bps);
195	memset(b->data + o % bps, 0, bps - o % bps);	188	memset(b->data + o % bps, 0, bps - o % bps);
196	b->dirty = true; /* need to sync node */	189	b->dirty = true; /* need to sync node */
197	block_put(b);	190	block_put(b);
198	}	191	}
199		192
200	if (o >= pos)	193	if (o >= pos)
201	return;	194	return;
202		195
203	/* zero out the initial part of the new cluster chain */	196	/* zero out the initial part of the new cluster chain */
204	for (o = boundary; o < pos; o += bps) {	197	for (o = boundary; o < pos; o += bps) {
205	b = _fat_block_get(bs, nodep->idx->dev_handle, mcl,	198	b = _fat_block_get(bs, nodep->idx->dev_handle, mcl,
206	(o - boundary) / bps);	199	(o - boundary) / bps);
207	memset(b->data, 0, min(bps, pos - o));	200	memset(b->data, 0, min(bps, pos - o));
208	b->dirty = true; /* need to sync node */	201	b->dirty = true; /* need to sync node */
209	block_put(b);	202	block_put(b);
210	}	203	}
211	}	204	}
212		205
213	/** Mark cluster in one instance of FAT.	206	/** Mark cluster in one instance of FAT.
214	*	207	*
215	* @param bs Buffer holding the boot sector for the file system.	208	* @param bs Buffer holding the boot sector for the file system.
216	* @param dev_handle Device handle for the file system.	209	* @param dev_handle Device handle for the file system.
217	* @param fatno Number of the FAT instance where to make the change.	210	* @param fatno Number of the FAT instance where to make the change.
218	* @param clst Cluster which is to be marked.	211	* @param clst Cluster which is to be marked.
219	* @param value Value mark the cluster with.	212	* @param value Value mark the cluster with.
220	*/	213	*/
221	void	214	void
222	fat_mark_cluster(fat_bs_t *bs, dev_handle_t dev_handle, unsigned fatno,	215	fat_mark_cluster(fat_bs_t *bs, dev_handle_t dev_handle, unsigned fatno,
223	fat_cluster_t clst, fat_cluster_t value)	216	fat_cluster_t clst, fat_cluster_t value)
224	{	217	{
225	block_t *b;	218	block_t *b;
226	uint16_t bps;	219	uint16_t bps;
227	uint16_t rscnt;	220	uint16_t rscnt;
228	uint16_t sf;	221	uint16_t sf;
229	fat_cluster_t *cp;	222	fat_cluster_t *cp;
230		223
231	bps = uint16_t_le2host(bs->bps);	224	bps = uint16_t_le2host(bs->bps);
232	rscnt = uint16_t_le2host(bs->rscnt);	225	rscnt = uint16_t_le2host(bs->rscnt);
233	sf = uint16_t_le2host(bs->sec_per_fat);	226	sf = uint16_t_le2host(bs->sec_per_fat);
234		227
235	assert(fatno < bs->fatcnt);	228	assert(fatno < bs->fatcnt);
236	b = block_get(dev_handle, rscnt + sf * fatno +	229	b = block_get(dev_handle, rscnt + sf * fatno +
237	(clst * sizeof(fat_cluster_t)) / bps);	230	(clst * sizeof(fat_cluster_t)) / bps);
238	cp = (fat_cluster_t *)b->data + clst % (bps / sizeof(fat_cluster_t));	231	cp = (fat_cluster_t *)b->data + clst % (bps / sizeof(fat_cluster_t));
239	*cp = host2uint16_t_le(value);	232	*cp = host2uint16_t_le(value);
240	b->dirty = true; /* need to sync block */	233	b->dirty = true; /* need to sync block */
241	block_put(b);	234	block_put(b);
242	}	235	}
243		236
244	/** Replay the allocatoin of clusters in all shadow instances of FAT.	237	/** Replay the allocatoin of clusters in all shadow instances of FAT.
245	*	238	*
246	* @param bs Buffer holding the boot sector of the file system.	239	* @param bs Buffer holding the boot sector of the file system.
247	* @param dev_handle Device handle of the file system.	240	* @param dev_handle Device handle of the file system.
248	* @param lifo Chain of allocated clusters.	241	* @param lifo Chain of allocated clusters.
249	* @param nclsts Number of clusters in the lifo chain.	242	* @param nclsts Number of clusters in the lifo chain.
250	*/	243	*/
251	void fat_alloc_shadow_clusters(fat_bs_t *bs, dev_handle_t dev_handle,	244	void fat_alloc_shadow_clusters(fat_bs_t *bs, dev_handle_t dev_handle,
252	fat_cluster_t *lifo, unsigned nclsts)	245	fat_cluster_t *lifo, unsigned nclsts)
253	{	246	{
254	uint8_t fatno;	247	uint8_t fatno;
255	unsigned c;	248	unsigned c;
256		249
257	for (fatno = FAT1 + 1; fatno < bs->fatcnt; fatno++) {	250	for (fatno = FAT1 + 1; fatno < bs->fatcnt; fatno++) {
258	for (c = 0; c < nclsts; c++) {	251	for (c = 0; c < nclsts; c++) {
259	fat_mark_cluster(bs, dev_handle, fatno, lifo[c],	252	fat_mark_cluster(bs, dev_handle, fatno, lifo[c],
260	c == 0 ? FAT_CLST_LAST1 : lifo[c - 1]);	253	c == 0 ? FAT_CLST_LAST1 : lifo[c - 1]);
261	}	254	}
262	}	255	}
263	}	256	}
264		257
265	/** Allocate clusters in FAT1.	258	/** Allocate clusters in FAT1.
266	*	259	*
267	* This function will attempt to allocate the requested number of clusters in	260	* This function will attempt to allocate the requested number of clusters in
268	* the first FAT instance. The FAT will be altered so that the allocated	261	* the first FAT instance. The FAT will be altered so that the allocated
269	* clusters form an independent chain (i.e. a chain which does not belong to any	262	* clusters form an independent chain (i.e. a chain which does not belong to any
270	* file yet).	263	* file yet).
271	*	264	*
272	* @param bs Buffer holding the boot sector of the file system.	265	* @param bs Buffer holding the boot sector of the file system.
273	* @param dev_handle Device handle of the file system.	266	* @param dev_handle Device handle of the file system.
274	* @param nclsts Number of clusters to allocate.	267	* @param nclsts Number of clusters to allocate.
275	* @param mcl Output parameter where the first cluster in the chain	268	* @param mcl Output parameter where the first cluster in the chain
276	* will be returned.	269	* will be returned.
277	* @param lcl Output parameter where the last cluster in the chain	270	* @param lcl Output parameter where the last cluster in the chain
278	* will be returned.	271	* will be returned.
279	*	272	*
280	* @return EOK on success, a negative error code otherwise.	273	* @return EOK on success, a negative error code otherwise.
281	*/	274	*/
282	int	275	int
283	fat_alloc_clusters(fat_bs_t *bs, dev_handle_t dev_handle, unsigned nclsts,	276	fat_alloc_clusters(fat_bs_t *bs, dev_handle_t dev_handle, unsigned nclsts,
284	fat_cluster_t mcl, fat_cluster_t lcl)	277	fat_cluster_t mcl, fat_cluster_t lcl)
285	{	278	{
286	uint16_t bps;	279	uint16_t bps;
287	uint16_t rscnt;	280	uint16_t rscnt;
288	uint16_t sf;	281	uint16_t sf;
289	block_t *blk;	282	block_t *blk;
290	fat_cluster_t lifo; / stack for storing free cluster numbers */	283	fat_cluster_t lifo; / stack for storing free cluster numbers */
291	unsigned found = 0; /* top of the free cluster number stack */	284	unsigned found = 0; /* top of the free cluster number stack */
292	unsigned b, c, cl;	285	unsigned b, c, cl;
293		286
294	lifo = (fat_cluster_t ) malloc(nclsts sizeof(fat_cluster_t));	287	lifo = (fat_cluster_t ) malloc(nclsts sizeof(fat_cluster_t));
295	if (lifo)	288	if (lifo)
296	return ENOMEM;	289	return ENOMEM;
297		290
298	bps = uint16_t_le2host(bs->bps);	291	bps = uint16_t_le2host(bs->bps);
299	rscnt = uint16_t_le2host(bs->rscnt);	292	rscnt = uint16_t_le2host(bs->rscnt);
300	sf = uint16_t_le2host(bs->sec_per_fat);	293	sf = uint16_t_le2host(bs->sec_per_fat);
301		294
302	/*	295	/*
303	* Search FAT1 for unused clusters.	296	* Search FAT1 for unused clusters.
304	*/	297	*/
305	futex_down(&fat_alloc_lock);	298	futex_down(&fat_alloc_lock);
306	for (b = 0, cl = 0; b < sf; blk++) {	299	for (b = 0, cl = 0; b < sf; blk++) {
307	blk = block_get(dev_handle, rscnt + b);	300	blk = block_get(dev_handle, rscnt + b);
308	for (c = 0; c < bps / sizeof(fat_cluster_t); c++, cl++) {	301	for (c = 0; c < bps / sizeof(fat_cluster_t); c++, cl++) {
309	fat_cluster_t clst = (fat_cluster_t )blk->data + c;	302	fat_cluster_t clst = (fat_cluster_t )blk->data + c;
310	if (uint16_t_le2host(*clst) == FAT_CLST_RES0) {	303	if (uint16_t_le2host(*clst) == FAT_CLST_RES0) {
311	/*	304	/*
312	* The cluster is free. Put it into our stack	305	* The cluster is free. Put it into our stack
313	* of found clusters and mark it as non-free.	306	* of found clusters and mark it as non-free.
314	*/	307	*/
315	lifo[found] = cl;	308	lifo[found] = cl;
316	*clst = (found == 0) ?	309	*clst = (found == 0) ?
317	host2uint16_t_le(FAT_CLST_LAST1) :	310	host2uint16_t_le(FAT_CLST_LAST1) :
318	host2uint16_t_le(lifo[found - 1]);	311	host2uint16_t_le(lifo[found - 1]);
319	blk->dirty = true; /* need to sync block */	312	blk->dirty = true; /* need to sync block */
320	if (++found == nclsts) {	313	if (++found == nclsts) {
321	/* we are almost done */	314	/* we are almost done */
322	block_put(blk);	315	block_put(blk);
323	/* update the shadow copies of FAT */	316	/* update the shadow copies of FAT */
324	fat_alloc_shadow_clusters(bs,	317	fat_alloc_shadow_clusters(bs,
325	dev_handle, lifo, nclsts);	318	dev_handle, lifo, nclsts);
326	*mcl = lifo[found - 1];	319	*mcl = lifo[found - 1];
327	*lcl = lifo[0];	320	*lcl = lifo[0];
328	free(lifo);	321	free(lifo);
329	futex_up(&fat_alloc_lock);	322	futex_up(&fat_alloc_lock);
330	return EOK;	323	return EOK;
331	}	324	}
332	}	325	}
333	}	326	}
334	block_put(blk);	327	block_put(blk);
335	}	328	}
336	futex_up(&fat_alloc_lock);	329	futex_up(&fat_alloc_lock);
337		330
338	/*	331	/*
339	* We could not find enough clusters. Now we need to free the clusters	332	* We could not find enough clusters. Now we need to free the clusters
340	* we have allocated so far.	333	* we have allocated so far.
341	*/	334	*/
342	while (found--) {	335	while (found--) {
343	fat_mark_cluster(bs, dev_handle, FAT1, lifo[found],	336	fat_mark_cluster(bs, dev_handle, FAT1, lifo[found],
344	FAT_CLST_RES0);	337	FAT_CLST_RES0);
345	}	338	}
346		339
347	free(lifo);	340	free(lifo);
348	return ENOSPC;	341	return ENOSPC;
349	}	342	}
350		343
351	/** Append a cluster chain to the last file cluster in all FATs.	344	/** Append a cluster chain to the last file cluster in all FATs.
352	*	345	*
353	* @param bs Buffer holding boot sector of the file system.	346	* @param bs Buffer holding boot sector of the file system.
354	* @param nodep Node representing the file.	347	* @param nodep Node representing the file.
355	* @param mcl First cluster of the cluster chain to append.	348	* @param mcl First cluster of the cluster chain to append.
356	*/	349	*/
357	void fat_append_clusters(fat_bs_t bs, fat_node_t nodep, fat_cluster_t mcl)	350	void fat_append_clusters(fat_bs_t bs, fat_node_t nodep, fat_cluster_t mcl)
358	{	351	{
359	dev_handle_t dev_handle = nodep->idx->dev_handle;	352	dev_handle_t dev_handle = nodep->idx->dev_handle;
360	fat_cluster_t lcl;	353	fat_cluster_t lcl;
361	uint8_t fatno;	354	uint8_t fatno;
362		355
363	if (fat_cluster_walk(bs, nodep->idx->dev_handle, nodep->firstc, &lcl,	356	if (fat_cluster_walk(bs, nodep->idx->dev_handle, nodep->firstc, &lcl,
364	NULL, (uint16_t) -1) == 0) {	357	(uint16_t) -1) == 0) {
365	/* No clusters allocated to the node yet. */	358	/* No clusters allocated to the node yet. */
366	nodep->firstc = host2uint16_t_le(mcl);	359	nodep->firstc = host2uint16_t_le(mcl);
367	nodep->dirty = true; /* need to sync node */	360	nodep->dirty = true; /* need to sync node */
368	return;	361	return;
369	}	362	}
370		363
371	for (fatno = FAT1; fatno < bs->fatcnt; fatno++)	364	for (fatno = FAT1; fatno < bs->fatcnt; fatno++)
372	fat_mark_cluster(bs, nodep->idx->dev_handle, fatno, lcl, mcl);	365	fat_mark_cluster(bs, nodep->idx->dev_handle, fatno, lcl, mcl);
373	}	366	}
374		367
375	/**	368	/**
376	* @}	369	* @}
377	*/	370	*/
378		371

Subversion Repositories HelenOS

(root)/trunk/uspace/srv/fs/fat/fat_fat.c – Rev 3551 → 3571