fs/btrfs/compat.h

#ifndef _COMPAT_H_
#define _COMPAT_H_

#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,26)
#define trylock_page(page) (!TestSetPageLocked(page))
#endif

#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,27)
static inline struct dentry *d_obtain_alias(struct inode *inode)
{
	struct dentry *d;

	if (!inode)
		return NULL;
	if (IS_ERR(inode))
		return ERR_CAST(inode);

	d = d_alloc_anon(inode);
	if (!d)
		iput(inode);
	return d;
}
#endif

#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,18)
static inline void btrfs_drop_nlink(struct inode *inode)
{
	inode->i_nlink--;
}

static inline void btrfs_inc_nlink(struct inode *inode)
{
	inode->i_nlink++;
}
#else
# define btrfs_drop_nlink(inode) drop_nlink(inode)
# define btrfs_inc_nlink(inode)	inc_nlink(inode)
#endif

/*
 * Even if AppArmor isn't enabled, it still has different prototypes.
 * Add more distro/version pairs here to declare which has AppArmor applied.
 */
#if defined(CONFIG_SUSE_KERNEL)
# if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,22)
# define REMOVE_SUID_PATH 1
# endif
#endif

/*
 * catch any other distros that have patched in apparmor.  This isn't
 * 100% reliable because it won't catch people that hand compile their
 * own distro kernels without apparmor compiled in.  But, it is better
 * than nothing.
 */
#ifdef CONFIG_SECURITY_APPARMOR
# define REMOVE_SUID_PATH 1
#endif

#endif /* _COMPAT_H_ */