81 lines
1.7 KiB
C
81 lines
1.7 KiB
C
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int phys2log(int phys, int stripe, int n, int layout)
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{
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/* In an 'n' disk array using 'layout',
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* in stripe 'stripe', the physical disc 'phys'
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* stores what logical chunk?
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* -1 mean parity.
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*
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*/
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switch(layout) {
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case ALGORITHM_LEFT_ASYMMETRIC:
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pd = (n-1) - (stripe % n);
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if (phys < pd)
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return phys;
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else if (phys == pd)
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return -1;
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else return phys-1;
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case ALGORITHM_RIGHT_ASYMMETRIC:
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pd = stripe % n;
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if (phys < pd)
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return phys;
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else if (phys == pd)
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return -1;
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else return phys-1;
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case ALGORITHM_LEFT_SYMMETRIC:
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pd = (n-1) - (stripe %n);
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if (phys < pd)
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return phys+ n-1-pd;
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else if (phys == pd)
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return -1;
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else return phys-pd-1;
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case ALGORITHM_RIGHT_SYMMETRIC:
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pd = stripe % n;
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if (phys < pd)
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return phys+ n-1-pd;
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else if (phys == pd)
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return -1;
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else return phys-pd-1;
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}
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return -2;
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}
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raid5_extend(unsigned long len, int chunksize, int layout, int n, int m, int rfds[], int wfds[])
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{
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static char buf[4096];
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unsigned long blocks = len/4;
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unsigned int blocksperchunk= chunksize/4096;
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unsigned long b;
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for (b=0; b<blocks; b++) {
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unsigned long stripe = b / blocksperchunk;
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unsigned int offset = b - (stripe*blocksperchunk);
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unsigned long chunk = stripe * (n-1);
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int src;
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for (src=0; src<n; src++) {
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int dnum, snum;
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if (read(rfds[src], buf, sizeof(buf)) != sizeof(buf)) {
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error();
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return 0;
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}
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snum = phys2log(src, stripe, n, layout);
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if (snum == -1)
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continue;
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chunk = stripe*(n-1)+snum;
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dstripe = chunk/(m-1);
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dnum = log2phys(chunk-(stripe*(m-1)), dstripe, m, layout);
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llseek(wfds[dnum], dstripe*chunksize+(offset*4096), 0);
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write(wfds[dnum], buf, sizeof(buf));
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}
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}
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}
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