WebSVN – HelenOS – Diff – /branches/sparc/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 <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;
 
/** 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 offset    Offset in blocks.
 *
 * @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,
    off_t offset)
{
    block_t *b;
    unsigned bps;
    unsigned spc;
    unsigned rscnt;     /* block address of the first FAT */
    unsigned fatcnt;
    unsigned rde;
    unsigned rds;       /* root directory size */
    unsigned sf;
    unsigned ssa;       /* size of the system area */
    unsigned clusters;
    fat_cluster_t clst = firstc;
    unsigned i;
 
    bps = uint16_t_le2host(bs->bps);
    spc = bs->spc;
    rscnt = uint16_t_le2host(bs->rscnt);
    fatcnt = bs->fatcnt;
    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 + fatcnt * sf + rds;
 
    if (firstc == FAT_CLST_ROOT) {
        /* root directory special case */
        assert(offset < rds);
        b = block_get(dev_handle, rscnt + fatcnt * sf + offset, bps);
        return b;
    }
 
    clusters = offset / spc;
    for (i = 0; i < clusters; i++) {
        unsigned fsec;  /* sector offset relative to FAT1 */
        unsigned fidx;  /* FAT1 entry index */
 
        assert(clst >= FAT_CLST_FIRST && clst < FAT_CLST_BAD);
        fsec = (clst * sizeof(fat_cluster_t)) / bps;
        fidx = clst % (bps / sizeof(fat_cluster_t));
        /* read FAT1 */
        b = block_get(dev_handle, rscnt + fsec, bps);
        clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]);
        assert(clst != FAT_CLST_BAD);
        assert(clst < FAT_CLST_LAST1);
        block_put(b);
    }
 
    b = block_get(dev_handle, ssa + (clst - FAT_CLST_FIRST) * spc +
        offset % spc, bps);
 
    return b;
}
 
/** Return number of blocks allocated to a file.
 *
 * @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 of the file.
 * @param lastc     If non-NULL, output argument holding the
 *          last cluster.
 *
 * @return      Number of blocks allocated to the file.
 */
uint16_t
_fat_blcks_get(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc,
    fat_cluster_t *lastc)
{
    block_t *b;
    unsigned bps;
    unsigned spc;
    unsigned rscnt;     /* block address of the first FAT */
    unsigned clusters = 0;
    fat_cluster_t clst = firstc;
 
    bps = uint16_t_le2host(bs->bps);
    spc = bs->spc;
    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) {
        unsigned fsec;  /* sector offset relative to FAT1 */
        unsigned fidx;  /* FAT1 entry index */
 
        assert(clst >= FAT_CLST_FIRST);
        if (lastc)
            *lastc = clst;      /* remember the last cluster */
        fsec = (clst * sizeof(fat_cluster_t)) / bps;
        fidx = clst % (bps / sizeof(fat_cluster_t));
        /* read FAT1 */
        b = block_get(dev_handle, rscnt + fsec, bps);
        clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]);
        assert(clst != FAT_CLST_BAD);
        block_put(b);
        clusters++;
    }
 
    if (lastc)
        *lastc = clst;
    return clusters * spc;
}
 
/** 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, 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, bps);
        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_blcks_get(bs, dev_handle, nodep->firstc, &lcl) == 0) {
        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 3517	Rev 3518
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 <errno.h>	43	#include <errno.h>
44	#include <byteorder.h>	44	#include <byteorder.h>
45	#include <align.h>	45	#include <align.h>
46	#include <assert.h>	46	#include <assert.h>
47	#include <futex.h>	47	#include <futex.h>
48		48
49	/**	49	/**
50	* The fat_alloc_lock futex protects all copies of the File Allocation Table	50	* The fat_alloc_lock futex protects all copies of the File Allocation Table
51	* during allocation of clusters. The lock does not have to be held durring	51	* during allocation of clusters. The lock does not have to be held durring
52	* deallocation of clusters.	52	* deallocation of clusters.
53	*/	53	*/
54	static futex_t fat_alloc_lock = FUTEX_INITIALIZER;	54	static futex_t fat_alloc_lock = FUTEX_INITIALIZER;
55		55
-		56	/** Read block from file located on a FAT file system.
-		57	*
-		58	* @param bs Buffer holding the boot sector of the file system.
-		59	* @param dev_handle Device handle of the file system.
-		60	* @param firstc First cluster used by the file. Can be zero if the file
-		61	* is empty.
-		62	* @param offset Offset in blocks.
-		63	*
-		64	* @return Block structure holding the requested block.
-		65	*/
56	block_t *	66	block_t *
57	_fat_block_get(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc,	67	_fat_block_get(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc,
58	off_t offset)	68	off_t offset)
59	{	69	{
60	block_t *b;	70	block_t *b;
61	unsigned bps;	71	unsigned bps;
62	unsigned spc;	72	unsigned spc;
63	unsigned rscnt; /* block address of the first FAT */	73	unsigned rscnt; /* block address of the first FAT */
64	unsigned fatcnt;	74	unsigned fatcnt;
65	unsigned rde;	75	unsigned rde;
66	unsigned rds; /* root directory size */	76	unsigned rds; /* root directory size */
67	unsigned sf;	77	unsigned sf;
68	unsigned ssa; /* size of the system area */	78	unsigned ssa; /* size of the system area */
69	unsigned clusters;	79	unsigned clusters;
70	fat_cluster_t clst = firstc;	80	fat_cluster_t clst = firstc;
71	unsigned i;	81	unsigned i;
72		82
73	bps = uint16_t_le2host(bs->bps);	83	bps = uint16_t_le2host(bs->bps);
74	spc = bs->spc;	84	spc = bs->spc;
75	rscnt = uint16_t_le2host(bs->rscnt);	85	rscnt = uint16_t_le2host(bs->rscnt);
76	fatcnt = bs->fatcnt;	86	fatcnt = bs->fatcnt;
77	rde = uint16_t_le2host(bs->root_ent_max);	87	rde = uint16_t_le2host(bs->root_ent_max);
78	sf = uint16_t_le2host(bs->sec_per_fat);	88	sf = uint16_t_le2host(bs->sec_per_fat);
79		89
80	rds = (sizeof(fat_dentry_t) * rde) / bps;	90	rds = (sizeof(fat_dentry_t) * rde) / bps;
81	rds += ((sizeof(fat_dentry_t) * rde) % bps != 0);	91	rds += ((sizeof(fat_dentry_t) * rde) % bps != 0);
82	ssa = rscnt + fatcnt * sf + rds;	92	ssa = rscnt + fatcnt * sf + rds;
83		93
84	if (firstc == FAT_CLST_ROOT) {	94	if (firstc == FAT_CLST_ROOT) {
85	/* root directory special case */	95	/* root directory special case */
86	assert(offset < rds);	96	assert(offset < rds);
87	b = block_get(dev_handle, rscnt + fatcnt * sf + offset, bps);	97	b = block_get(dev_handle, rscnt + fatcnt * sf + offset, bps);
88	return b;	98	return b;
89	}	99	}
90		100
91	clusters = offset / spc;	101	clusters = offset / spc;
92	for (i = 0; i < clusters; i++) {	102	for (i = 0; i < clusters; i++) {
93	unsigned fsec; /* sector offset relative to FAT1 */	103	unsigned fsec; /* sector offset relative to FAT1 */
94	unsigned fidx; /* FAT1 entry index */	104	unsigned fidx; /* FAT1 entry index */
95		105
96	assert(clst >= FAT_CLST_FIRST && clst < FAT_CLST_BAD);	106	assert(clst >= FAT_CLST_FIRST && clst < FAT_CLST_BAD);
97	fsec = (clst * sizeof(fat_cluster_t)) / bps;	107	fsec = (clst * sizeof(fat_cluster_t)) / bps;
98	fidx = clst % (bps / sizeof(fat_cluster_t));	108	fidx = clst % (bps / sizeof(fat_cluster_t));
99	/* read FAT1 */	109	/* read FAT1 */
100	b = block_get(dev_handle, rscnt + fsec, bps);	110	b = block_get(dev_handle, rscnt + fsec, bps);
101	clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]);	111	clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]);
102	assert(clst != FAT_CLST_BAD);	112	assert(clst != FAT_CLST_BAD);
103	assert(clst < FAT_CLST_LAST1);	113	assert(clst < FAT_CLST_LAST1);
104	block_put(b);	114	block_put(b);
105	}	115	}
106		116
107	b = block_get(dev_handle, ssa + (clst - FAT_CLST_FIRST) * spc +	117	b = block_get(dev_handle, ssa + (clst - FAT_CLST_FIRST) * spc +
108	offset % spc, bps);	118	offset % spc, bps);
109		119
110	return b;	120	return b;
111	}	121	}
112		122
113	/** Return number of blocks allocated to a file.	123	/** Return number of blocks allocated to a file.
114	*	124	*
115	* @param bs Buffer holding the boot sector for the file.	125	* @param bs Buffer holding the boot sector for the file.
116	* @param dev_handle Device handle of the device with the file.	126	* @param dev_handle Device handle of the device with the file.
117	* @param firstc First cluster of the file.	127	* @param firstc First cluster of the file.
118	* @param lastc If non-NULL, output argument holding the	128	* @param lastc If non-NULL, output argument holding the
119	* last cluster.	129	* last cluster.
120	*	130	*
121	* @return Number of blocks allocated to the file.	131	* @return Number of blocks allocated to the file.
122	*/	132	*/
123	uint16_t	133	uint16_t
124	_fat_blcks_get(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc,	134	_fat_blcks_get(fat_bs_t *bs, dev_handle_t dev_handle, fat_cluster_t firstc,
125	fat_cluster_t *lastc)	135	fat_cluster_t *lastc)
126	{	136	{
127	block_t *b;	137	block_t *b;
128	unsigned bps;	138	unsigned bps;
129	unsigned spc;	139	unsigned spc;
130	unsigned rscnt; /* block address of the first FAT */	140	unsigned rscnt; /* block address of the first FAT */
131	unsigned clusters = 0;	141	unsigned clusters = 0;
132	fat_cluster_t clst = firstc;	142	fat_cluster_t clst = firstc;
133		143
134	bps = uint16_t_le2host(bs->bps);	144	bps = uint16_t_le2host(bs->bps);
135	spc = bs->spc;	145	spc = bs->spc;
136	rscnt = uint16_t_le2host(bs->rscnt);	146	rscnt = uint16_t_le2host(bs->rscnt);
137		147
138	if (firstc == FAT_CLST_RES0) {	148	if (firstc == FAT_CLST_RES0) {
139	/* No space allocated to the file. */	149	/* No space allocated to the file. */
140	if (lastc)	150	if (lastc)
141	*lastc = firstc;	151	*lastc = firstc;
142	return 0;	152	return 0;
143	}	153	}
144		154
145	while (clst < FAT_CLST_LAST1) {	155	while (clst < FAT_CLST_LAST1) {
146	unsigned fsec; /* sector offset relative to FAT1 */	156	unsigned fsec; /* sector offset relative to FAT1 */
147	unsigned fidx; /* FAT1 entry index */	157	unsigned fidx; /* FAT1 entry index */
148		158
149	assert(clst >= FAT_CLST_FIRST);	159	assert(clst >= FAT_CLST_FIRST);
150	if (lastc)	160	if (lastc)
151	lastc = clst; / remember the last cluster */	161	lastc = clst; / remember the last cluster */
152	fsec = (clst * sizeof(fat_cluster_t)) / bps;	162	fsec = (clst * sizeof(fat_cluster_t)) / bps;
153	fidx = clst % (bps / sizeof(fat_cluster_t));	163	fidx = clst % (bps / sizeof(fat_cluster_t));
154	/* read FAT1 */	164	/* read FAT1 */
155	b = block_get(dev_handle, rscnt + fsec, bps);	165	b = block_get(dev_handle, rscnt + fsec, bps);
156	clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]);	166	clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]);
157	assert(clst != FAT_CLST_BAD);	167	assert(clst != FAT_CLST_BAD);
158	block_put(b);	168	block_put(b);
159	clusters++;	169	clusters++;
160	}	170	}
161		171
162	if (lastc)	172	if (lastc)
163	*lastc = clst;	173	*lastc = clst;
164	return clusters * spc;	174	return clusters * spc;
165	}	175	}
166		176
167	/** Fill the gap between EOF and a new file position.	177	/** Fill the gap between EOF and a new file position.
168	*	178	*
169	* @param bs Buffer holding the boot sector for nodep.	179	* @param bs Buffer holding the boot sector for nodep.
170	* @param nodep FAT node with the gap.	180	* @param nodep FAT node with the gap.
171	* @param mcl First cluster in an independent cluster chain that will	181	* @param mcl First cluster in an independent cluster chain that will
172	* be later appended to the end of the node's own cluster	182	* be later appended to the end of the node's own cluster
173	* chain. If pos is still in the last allocated cluster,	183	* chain. If pos is still in the last allocated cluster,
174	* this argument is ignored.	184	* this argument is ignored.
175	* @param pos Position in the last node block.	185	* @param pos Position in the last node block.
176	*/	186	*/
177	void fat_fill_gap(fat_bs_t bs, fat_node_t nodep, fat_cluster_t mcl, off_t pos)	187	void fat_fill_gap(fat_bs_t bs, fat_node_t nodep, fat_cluster_t mcl, off_t pos)
178	{	188	{
179	uint16_t bps;	189	uint16_t bps;
180	unsigned spc;	190	unsigned spc;
181	block_t *b;	191	block_t *b;
182	off_t o, boundary;	192	off_t o, boundary;
183		193
184	bps = uint16_t_le2host(bs->bps);	194	bps = uint16_t_le2host(bs->bps);
185	spc = bs->spc;	195	spc = bs->spc;
186		196
187	boundary = ROUND_UP(nodep->size, bps * spc);	197	boundary = ROUND_UP(nodep->size, bps * spc);
188		198
189	/* zero out already allocated space */	199	/* zero out already allocated space */
190	for (o = nodep->size - 1; o < pos && o < boundary;	200	for (o = nodep->size - 1; o < pos && o < boundary;
191	o = ALIGN_DOWN(o + bps, bps)) {	201	o = ALIGN_DOWN(o + bps, bps)) {
192	b = fat_block_get(bs, nodep, o / bps);	202	b = fat_block_get(bs, nodep, o / bps);
193	memset(b->data + o % bps, 0, bps - o % bps);	203	memset(b->data + o % bps, 0, bps - o % bps);
194	b->dirty = true; /* need to sync node */	204	b->dirty = true; /* need to sync node */
195	block_put(b);	205	block_put(b);
196	}	206	}
197		207
198	if (o >= pos)	208	if (o >= pos)
199	return;	209	return;
200		210
201	/* zero out the initial part of the new cluster chain */	211	/* zero out the initial part of the new cluster chain */
202	for (o = boundary; o < pos; o += bps) {	212	for (o = boundary; o < pos; o += bps) {
203	b = _fat_block_get(bs, nodep->idx->dev_handle, mcl,	213	b = _fat_block_get(bs, nodep->idx->dev_handle, mcl,
204	(o - boundary) / bps);	214	(o - boundary) / bps);
205	memset(b->data, 0, min(bps, pos - o));	215	memset(b->data, 0, min(bps, pos - o));
206	b->dirty = true; /* need to sync node */	216	b->dirty = true; /* need to sync node */
207	block_put(b);	217	block_put(b);
208	}	218	}
209	}	219	}
210		220
-		221	/** Mark cluster in one instance of FAT.
-		222	*
-		223	* @param bs Buffer holding the boot sector for the file system.
-		224	* @param dev_handle Device handle for the file system.
-		225	* @param fatno Number of the FAT instance where to make the change.
-		226	* @param clst Cluster which is to be marked.
-		227	* @param value Value mark the cluster with.
-		228	*/
211	void	229	void
212	fat_mark_cluster(fat_bs_t *bs, dev_handle_t dev_handle, unsigned fatno,	230	fat_mark_cluster(fat_bs_t *bs, dev_handle_t dev_handle, unsigned fatno,
213	fat_cluster_t clst, fat_cluster_t value)	231	fat_cluster_t clst, fat_cluster_t value)
214	{	232	{
215	block_t *b;	233	block_t *b;
216	uint16_t bps;	234	uint16_t bps;
217	uint16_t rscnt;	235	uint16_t rscnt;
218	uint16_t sf;	236	uint16_t sf;
219	fat_cluster_t *cp;	237	fat_cluster_t *cp;
220		238
221	bps = uint16_t_le2host(bs->bps);	239	bps = uint16_t_le2host(bs->bps);
222	rscnt = uint16_t_le2host(bs->rscnt);	240	rscnt = uint16_t_le2host(bs->rscnt);
223	sf = uint16_t_le2host(bs->sec_per_fat);	241	sf = uint16_t_le2host(bs->sec_per_fat);
224		242
225	assert(fatno < bs->fatcnt);	243	assert(fatno < bs->fatcnt);
226	b = block_get(dev_handle, rscnt + sf * fatno +	244	b = block_get(dev_handle, rscnt + sf * fatno +
227	(clst * sizeof(fat_cluster_t)) / bps, bps);	245	(clst * sizeof(fat_cluster_t)) / bps, bps);
228	cp = (fat_cluster_t *)b->data + clst % (bps / sizeof(fat_cluster_t));	246	cp = (fat_cluster_t *)b->data + clst % (bps / sizeof(fat_cluster_t));
229	*cp = host2uint16_t_le(value);	247	*cp = host2uint16_t_le(value);
230	b->dirty = true; /* need to sync block */	248	b->dirty = true; /* need to sync block */
231	block_put(b);	249	block_put(b);
232	}	250	}
233		251
-		252	/** Replay the allocatoin of clusters in all shadow instances of FAT.
-		253	*
-		254	* @param bs Buffer holding the boot sector of the file system.
-		255	* @param dev_handle Device handle of the file system.
-		256	* @param lifo Chain of allocated clusters.
-		257	* @param nclsts Number of clusters in the lifo chain.
-		258	*/
234	void fat_alloc_shadow_clusters(fat_bs_t *bs, dev_handle_t dev_handle,	259	void fat_alloc_shadow_clusters(fat_bs_t *bs, dev_handle_t dev_handle,
235	fat_cluster_t *lifo, unsigned nclsts)	260	fat_cluster_t *lifo, unsigned nclsts)
236	{	261	{
237	uint8_t fatno;	262	uint8_t fatno;
238	unsigned c;	263	unsigned c;
239		264
240	for (fatno = FAT1 + 1; fatno < bs->fatcnt; fatno++) {	265	for (fatno = FAT1 + 1; fatno < bs->fatcnt; fatno++) {
241	for (c = 0; c < nclsts; c++) {	266	for (c = 0; c < nclsts; c++) {
242	fat_mark_cluster(bs, dev_handle, fatno, lifo[c],	267	fat_mark_cluster(bs, dev_handle, fatno, lifo[c],
243	c == 0 ? FAT_CLST_LAST1 : lifo[c - 1]);	268	c == 0 ? FAT_CLST_LAST1 : lifo[c - 1]);
244	}	269	}
245	}	270	}
246	}	271	}
247		272
-		273	/** Allocate clusters in FAT1.
-		274	*
-		275	* This function will attempt to allocate the requested number of clusters in
-		276	* the first FAT instance. The FAT will be altered so that the allocated
-		277	* clusters form an independent chain (i.e. a chain which does not belong to any
-		278	* file yet).
-		279	*
-		280	* @param bs Buffer holding the boot sector of the file system.
-		281	* @param dev_handle Device handle of the file system.
-		282	* @param nclsts Number of clusters to allocate.
-		283	* @param mcl Output parameter where the first cluster in the chain
-		284	* will be returned.
-		285	* @param lcl Output parameter where the last cluster in the chain
-		286	* will be returned.
-		287	*
-		288	* @return EOK on success, a negative error code otherwise.
-		289	*/
248	int	290	int
249	fat_alloc_clusters(fat_bs_t *bs, dev_handle_t dev_handle, unsigned nclsts,	291	fat_alloc_clusters(fat_bs_t *bs, dev_handle_t dev_handle, unsigned nclsts,
250	fat_cluster_t mcl, fat_cluster_t lcl)	292	fat_cluster_t mcl, fat_cluster_t lcl)
251	{	293	{
252	uint16_t bps;	294	uint16_t bps;
253	uint16_t rscnt;	295	uint16_t rscnt;
254	uint16_t sf;	296	uint16_t sf;
255	block_t *blk;	297	block_t *blk;
256	fat_cluster_t lifo; / stack for storing free cluster numbers */	298	fat_cluster_t lifo; / stack for storing free cluster numbers */
257	unsigned found = 0; /* top of the free cluster number stack */	299	unsigned found = 0; /* top of the free cluster number stack */
258	unsigned b, c, cl;	300	unsigned b, c, cl;
259		301
260	lifo = (fat_cluster_t ) malloc(nclsts sizeof(fat_cluster_t));	302	lifo = (fat_cluster_t ) malloc(nclsts sizeof(fat_cluster_t));
261	if (lifo)	303	if (lifo)
262	return ENOMEM;	304	return ENOMEM;
263		305
264	bps = uint16_t_le2host(bs->bps);	306	bps = uint16_t_le2host(bs->bps);
265	rscnt = uint16_t_le2host(bs->rscnt);	307	rscnt = uint16_t_le2host(bs->rscnt);
266	sf = uint16_t_le2host(bs->sec_per_fat);	308	sf = uint16_t_le2host(bs->sec_per_fat);
267		309
268	/*	310	/*
269	* Search FAT1 for unused clusters.	311	* Search FAT1 for unused clusters.
270	*/	312	*/
271	futex_down(&fat_alloc_lock);	313	futex_down(&fat_alloc_lock);
272	for (b = 0, cl = 0; b < sf; blk++) {	314	for (b = 0, cl = 0; b < sf; blk++) {
273	blk = block_get(dev_handle, rscnt + b, bps);	315	blk = block_get(dev_handle, rscnt + b, bps);
274	for (c = 0; c < bps / sizeof(fat_cluster_t); c++, cl++) {	316	for (c = 0; c < bps / sizeof(fat_cluster_t); c++, cl++) {
275	fat_cluster_t clst = (fat_cluster_t )blk->data + c;	317	fat_cluster_t clst = (fat_cluster_t )blk->data + c;
276	if (uint16_t_le2host(*clst) == FAT_CLST_RES0) {	318	if (uint16_t_le2host(*clst) == FAT_CLST_RES0) {
277	/*	319	/*
278	* The cluster is free. Put it into our stack	320	* The cluster is free. Put it into our stack
279	* of found clusters and mark it as non-free.	321	* of found clusters and mark it as non-free.
280	*/	322	*/
281	lifo[found] = cl;	323	lifo[found] = cl;
282	*clst = (found == 0) ?	324	*clst = (found == 0) ?
283	host2uint16_t_le(FAT_CLST_LAST1) :	325	host2uint16_t_le(FAT_CLST_LAST1) :
284	host2uint16_t_le(lifo[found - 1]);	326	host2uint16_t_le(lifo[found - 1]);
285	blk->dirty = true; /* need to sync block */	327	blk->dirty = true; /* need to sync block */
286	if (++found == nclsts) {	328	if (++found == nclsts) {
287	/* we are almost done */	329	/* we are almost done */
288	block_put(blk);	330	block_put(blk);
289	/* update the shadow copies of FAT */	331	/* update the shadow copies of FAT */
290	fat_alloc_shadow_clusters(bs,	332	fat_alloc_shadow_clusters(bs,
291	dev_handle, lifo, nclsts);	333	dev_handle, lifo, nclsts);
292	*mcl = lifo[found - 1];	334	*mcl = lifo[found - 1];
293	*lcl = lifo[0];	335	*lcl = lifo[0];
294	free(lifo);	336	free(lifo);
295	futex_up(&fat_alloc_lock);	337	futex_up(&fat_alloc_lock);
296	return EOK;	338	return EOK;
297	}	339	}
298	}	340	}
299	}	341	}
300	block_put(blk);	342	block_put(blk);
301	}	343	}
302	futex_up(&fat_alloc_lock);	344	futex_up(&fat_alloc_lock);
303		345
304	/*	346	/*
305	* We could not find enough clusters. Now we need to free the clusters	347	* We could not find enough clusters. Now we need to free the clusters
306	* we have allocated so far.	348	* we have allocated so far.
307	*/	349	*/
308	while (found--) {	350	while (found--) {
309	fat_mark_cluster(bs, dev_handle, FAT1, lifo[found],	351	fat_mark_cluster(bs, dev_handle, FAT1, lifo[found],
310	FAT_CLST_RES0);	352	FAT_CLST_RES0);
311	}	353	}
312		354
313	free(lifo);	355	free(lifo);
314	return ENOSPC;	356	return ENOSPC;
315	}	357	}
316		358
-		359	/** Append a cluster chain to the last file cluster in all FATs.
-		360	*
-		361	* @param bs Buffer holding boot sector of the file system.
-		362	* @param nodep Node representing the file.
-		363	* @param mcl First cluster of the cluster chain to append.
-		364	*/
317	void fat_append_clusters(fat_bs_t bs, fat_node_t nodep, fat_cluster_t mcl)	365	void fat_append_clusters(fat_bs_t bs, fat_node_t nodep, fat_cluster_t mcl)
318	{	366	{
319	dev_handle_t dev_handle = nodep->idx->dev_handle;	367	dev_handle_t dev_handle = nodep->idx->dev_handle;
320	fat_cluster_t lcl;	368	fat_cluster_t lcl;
321	uint8_t fatno;	369	uint8_t fatno;
322		370
323	if (_fat_blcks_get(bs, dev_handle, nodep->firstc, &lcl) == 0) {	371	if (_fat_blcks_get(bs, dev_handle, nodep->firstc, &lcl) == 0) {
324	nodep->firstc = host2uint16_t_le(mcl);	372	nodep->firstc = host2uint16_t_le(mcl);
325	nodep->dirty = true; /* need to sync node */	373	nodep->dirty = true; /* need to sync node */
326	return;	374	return;
327	}	375	}
328		376
329	for (fatno = FAT1; fatno < bs->fatcnt; fatno++)	377	for (fatno = FAT1; fatno < bs->fatcnt; fatno++)
330	fat_mark_cluster(bs, nodep->idx->dev_handle, fatno, lcl, mcl);	378	fat_mark_cluster(bs, nodep->idx->dev_handle, fatno, lcl, mcl);
331	}	379	}
332		380
333	/**	381	/**
334	* @}	382	* @}
335	*/	383	*/
336		384

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(root)/branches/sparc/uspace/srv/fs/fat/fat_fat.c @ 4759 – Rev 3517 → 3518