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Revision f104d044376aadcee74605d66b8d9dc2e145782c authored by Josef Bacik on 14 October 2011, 17:56:58 UTC, committed by Josef Bacik on 19 October 2011, 19:12:57 UTC 
Btrfs: wait for ordered extents if we're in trouble when shrinking delalloc
 
The only way we actually reclaim delalloc space is waiting for the IO to
completely finish.  Usually we kick off a bunch of IO and wait for a little bit
and hope we can make our reservation, and usually this works out pretty well.
With overcommit however we can get seriously underwater if we're filling up the
disk quickly, so we need to be able to force the delalloc shrinker to wait for
the ordered IO to finish to give us a better chance of actually reclaiming
enough space to get our reservation.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
1 parent bbb495c
Raw File
miscthings.c 
#include "linux/threads.h"
#include "linux/stddef.h"  // for NULL
#include "linux/elf.h"  // for AT_NULL

/* The following function nicked from arch/ppc/kernel/process.c and
 * adapted slightly */
/*
 * XXX ld.so expects the auxiliary table to start on
 * a 16-byte boundary, so we have to find it and
 * move it up. :-(
 */
void shove_aux_table(unsigned long sp)
{
	int argc;
	char *p;
	unsigned long e;
	unsigned long aux_start, offset;

	argc = *(int *)sp;
	sp += sizeof(int) + (argc + 1) * sizeof(char *);
	/* skip over the environment pointers */
	do {
		p = *(char **)sp;
		sp += sizeof(char *);
	} while (p != NULL);
	aux_start = sp;
	/* skip to the end of the auxiliary table */
	do {
		e = *(unsigned long *)sp;
		sp += 2 * sizeof(unsigned long);
	} while (e != AT_NULL);
	offset = ((aux_start + 15) & ~15) - aux_start;
	if (offset != 0) {
		do {
			sp -= sizeof(unsigned long);
			e = *(unsigned long *)sp;
			*(unsigned long *)(sp + offset) = e;
		} while (sp > aux_start);
	}
}
/* END stuff taken from arch/ppc/kernel/process.c */
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