Btrfs: use FLUSH_LIMIT for relocation in reserve_metadata_bytes

We used to allow you to set FLUSH_ALL and then just wouldn't do things like
commit transactions or wait on ordered extents if we noticed you were in a
transaction.  However now that all the flushing for FLUSH_ALL is asynchronous
we've lost the ability to tell, and we could end up deadlocking.  So instead use
FLUSH_LIMIT in reserve_metadata_bytes in relocation and then return -EAGAIN if
we error out to preserve the previous behavior.  I've also added an ASSERT() to
catch anybody else who tries to do this.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

path: root/lockme.h

#ifndef LOCKME_H
#define LOCKME_H

#include <sys/mman.h>

#include "die.h"

static inline void xlockme(void)
{
	if (mlockall(MCL_CURRENT | MCL_FUTURE) != 0)
		panic("Cannot lock pages!\n");
}

static inline void xunlockme(void)
{
	munlockall();
}

#endif /* LOCKME_H */