linux-vybrid_public/fs/ceph/ceph_fs.c

/*
 * Some non-inline ceph helpers
 */
#include "types.h"

/*
 * return true if @layout appears to be valid
 */
int ceph_file_layout_is_valid(const struct ceph_file_layout *layout)
{
	__u32 su = le32_to_cpu(layout->fl_stripe_unit);
	__u32 sc = le32_to_cpu(layout->fl_stripe_count);
	__u32 os = le32_to_cpu(layout->fl_object_size);

	/* stripe unit, object size must be non-zero, 64k increment */
	if (!su || (su & (CEPH_MIN_STRIPE_UNIT-1)))
		return 0;
	if (!os || (os & (CEPH_MIN_STRIPE_UNIT-1)))
		return 0;
	/* object size must be a multiple of stripe unit */
	if (os < su || os % su)
		return 0;
	/* stripe count must be non-zero */
	if (!sc)
		return 0;
	return 1;
}


int ceph_flags_to_mode(int flags)
{
#ifdef O_DIRECTORY  /* fixme */
	if ((flags & O_DIRECTORY) == O_DIRECTORY)
		return CEPH_FILE_MODE_PIN;
#endif
#ifdef O_LAZY
	if (flags & O_LAZY)
		return CEPH_FILE_MODE_LAZY;
#endif
	if ((flags & O_APPEND) == O_APPEND)
		flags |= O_WRONLY;

	flags &= O_ACCMODE;
	if ((flags & O_RDWR) == O_RDWR)
		return CEPH_FILE_MODE_RDWR;
	if ((flags & O_WRONLY) == O_WRONLY)
		return CEPH_FILE_MODE_WR;
	return CEPH_FILE_MODE_RD;
}

int ceph_caps_for_mode(int mode)
{
	switch (mode) {
	case CEPH_FILE_MODE_PIN:
		return CEPH_CAP_PIN;
	case CEPH_FILE_MODE_RD:
		return CEPH_CAP_PIN | CEPH_CAP_FILE_SHARED |
			CEPH_CAP_FILE_RD | CEPH_CAP_FILE_CACHE;
	case CEPH_FILE_MODE_RDWR:
		return CEPH_CAP_PIN | CEPH_CAP_FILE_SHARED |
			CEPH_CAP_FILE_EXCL |
			CEPH_CAP_FILE_RD | CEPH_CAP_FILE_CACHE |
			CEPH_CAP_FILE_WR | CEPH_CAP_FILE_BUFFER |
			CEPH_CAP_AUTH_SHARED | CEPH_CAP_AUTH_EXCL |
			CEPH_CAP_XATTR_SHARED | CEPH_CAP_XATTR_EXCL;
	case CEPH_FILE_MODE_WR:
		return CEPH_CAP_PIN | CEPH_CAP_FILE_SHARED |
			CEPH_CAP_FILE_EXCL |
			CEPH_CAP_FILE_WR | CEPH_CAP_FILE_BUFFER |
			CEPH_CAP_AUTH_SHARED | CEPH_CAP_AUTH_EXCL |
			CEPH_CAP_XATTR_SHARED | CEPH_CAP_XATTR_EXCL;
	}
	return 0;
}

/*
 * Robert Jenkin's hash function.
 * http://burtleburtle.net/bob/hash/evahash.html
 * This is in the public domain.
 */
#define mix(a, b, c)						\
	do {							\
		a = a - b;  a = a - c;  a = a ^ (c >> 13);	\
		b = b - c;  b = b - a;  b = b ^ (a << 8);	\
		c = c - a;  c = c - b;  c = c ^ (b >> 13);	\
		a = a - b;  a = a - c;  a = a ^ (c >> 12);	\
		b = b - c;  b = b - a;  b = b ^ (a << 16);	\
		c = c - a;  c = c - b;  c = c ^ (b >> 5);	\
		a = a - b;  a = a - c;  a = a ^ (c >> 3);	\
		b = b - c;  b = b - a;  b = b ^ (a << 10);	\
		c = c - a;  c = c - b;  c = c ^ (b >> 15);	\
	} while (0)

unsigned int ceph_full_name_hash(const char *str, unsigned int length)
{
	const unsigned char *k = (const unsigned char *)str;
	__u32 a, b, c;  /* the internal state */
	__u32 len;      /* how many key bytes still need mixing */

	/* Set up the internal state */
	len = length;
	a = 0x9e3779b9;      /* the golden ratio; an arbitrary value */
	b = a;
	c = 0;               /* variable initialization of internal state */

	/* handle most of the key */
	while (len >= 12) {
		a = a + (k[0] + ((__u32)k[1] << 8) + ((__u32)k[2] << 16) +
			 ((__u32)k[3] << 24));
		b = b + (k[4] + ((__u32)k[5] << 8) + ((__u32)k[6] << 16) +
			 ((__u32)k[7] << 24));
		c = c + (k[8] + ((__u32)k[9] << 8) + ((__u32)k[10] << 16) +
			 ((__u32)k[11] << 24));
		mix(a, b, c);
		k = k + 12;
		len = len - 12;
	}

	/* handle the last 11 bytes */
	c = c + length;
	switch (len) {            /* all the case statements fall through */
	case 11:
		c = c + ((__u32)k[10] << 24);
	case 10:
		c = c + ((__u32)k[9] << 16);
	case 9:
		c = c + ((__u32)k[8] << 8);
		/* the first byte of c is reserved for the length */
	case 8:
		b = b + ((__u32)k[7] << 24);
	case 7:
		b = b + ((__u32)k[6] << 16);
	case 6:
		b = b + ((__u32)k[5] << 8);
	case 5:
		b = b + k[4];
	case 4:
		a = a + ((__u32)k[3] << 24);
	case 3:
		a = a + ((__u32)k[2] << 16);
	case 2:
		a = a + ((__u32)k[1] << 8);
	case 1:
		a = a + k[0];
		/* case 0: nothing left to add */
	}
	mix(a, b, c);

	return c;
}