Revision fd45e4784164d1017521086524e3442318c67370 authored by Dave Chinner on 02 January 2010, 02:38:56 UTC, committed by Alex Elder on 10 January 2010, 18:22:02 UTC
When we search for and find a busy extent during allocation we force the log out to ensure the extent free transaction is on disk before the allocation transaction. The current implementation has a subtle bug in it--it does not handle multiple overlapping ranges. That is, if we free lots of little extents into a single contiguous extent, then allocate the contiguous extent, the busy search code stops searching at the first extent it finds that overlaps the allocated range. It then uses the commit LSN of the transaction to force the log out to. Unfortunately, the other busy ranges might have more recent commit LSNs than the first busy extent that is found, and this results in xfs_alloc_search_busy() returning before all the extent free transactions are on disk for the range being allocated. This can lead to potential metadata corruption or stale data exposure after a crash because log replay won't replay all the extent free transactions that cover the allocation range. Modified-by: Alex Elder <aelder@sgi.com> (Dropped the "found" argument from the xfs_alloc_busysearch trace event.) Signed-off-by: Dave Chinner <david@fromorbit.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com>
1 parent 44e08c4
mk_elfconfig.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <elf.h>
int
main(int argc, char **argv)
{
unsigned char ei[EI_NIDENT];
union { short s; char c[2]; } endian_test;
if (fread(ei, 1, EI_NIDENT, stdin) != EI_NIDENT) {
fprintf(stderr, "Error: input truncated\n");
return 1;
}
if (memcmp(ei, ELFMAG, SELFMAG) != 0) {
fprintf(stderr, "Error: not ELF\n");
return 1;
}
switch (ei[EI_CLASS]) {
case ELFCLASS32:
printf("#define KERNEL_ELFCLASS ELFCLASS32\n");
break;
case ELFCLASS64:
printf("#define KERNEL_ELFCLASS ELFCLASS64\n");
break;
default:
exit(1);
}
switch (ei[EI_DATA]) {
case ELFDATA2LSB:
printf("#define KERNEL_ELFDATA ELFDATA2LSB\n");
break;
case ELFDATA2MSB:
printf("#define KERNEL_ELFDATA ELFDATA2MSB\n");
break;
default:
exit(1);
}
if (sizeof(unsigned long) == 4) {
printf("#define HOST_ELFCLASS ELFCLASS32\n");
} else if (sizeof(unsigned long) == 8) {
printf("#define HOST_ELFCLASS ELFCLASS64\n");
}
endian_test.s = 0x0102;
if (memcmp(endian_test.c, "\x01\x02", 2) == 0)
printf("#define HOST_ELFDATA ELFDATA2MSB\n");
else if (memcmp(endian_test.c, "\x02\x01", 2) == 0)
printf("#define HOST_ELFDATA ELFDATA2LSB\n");
else
exit(1);
return 0;
}
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