diff options
| -rw-r--r-- | xlators/cluster/dht/src/dht-helper.c | 87 |
1 files changed, 82 insertions, 5 deletions
diff --git a/xlators/cluster/dht/src/dht-helper.c b/xlators/cluster/dht/src/dht-helper.c index ecd06e394da..9a00fe6481c 100644 --- a/xlators/cluster/dht/src/dht-helper.c +++ b/xlators/cluster/dht/src/dht-helper.c @@ -40,6 +40,43 @@ dht_frame_return (call_frame_t *frame) } +static uint64_t +dht_bits_for (uint64_t num) +{ + uint64_t bits = 0, ctrl = 1; + + while (ctrl < num) { + ctrl *= 2; + bits ++; + } + + return bits; +} + +/* + * A slightly "updated" version of the algorithm described in the commit log + * is used here. + * + * The only enhancement is that: + * + * - The number of bits used by the backend filesystem for HUGE d_off which + * is described as 63, and + * - The number of bits used by the d_off presented by the transformation + * upwards which is described as 64, are both made "configurable." + */ + + +#define BACKEND_D_OFF_BITS 63 +#define PRESENT_D_OFF_BITS 63 + +#define ONE 1ULL +#define MASK (~0ULL) +#define PRESENT_MASK (MASK >> (64 - PRESENT_D_OFF_BITS)) +#define BACKEND_MASK (MASK >> (64 - BACKEND_D_OFF_BITS)) + +#define TOP_BIT (ONE << (PRESENT_D_OFF_BITS - 1)) +#define SHIFT_BITS (max (0, (BACKEND_D_OFF_BITS - PRESENT_D_OFF_BITS + 1))) + int dht_itransform (xlator_t *this, xlator_t *subvol, uint64_t x, uint64_t *y_p) { @@ -47,6 +84,9 @@ dht_itransform (xlator_t *this, xlator_t *subvol, uint64_t x, uint64_t *y_p) int cnt = 0; int max = 0; uint64_t y = 0; + uint64_t hi_mask = 0; + uint64_t off_mask = 0; + int max_bits = 0; if (x == ((uint64_t) -1)) { y = (uint64_t) -1; @@ -60,7 +100,23 @@ dht_itransform (xlator_t *this, xlator_t *subvol, uint64_t x, uint64_t *y_p) max = conf->subvolume_cnt; cnt = dht_subvol_cnt (this, subvol); - y = ((x * max) + cnt); + if (max == 1) { + y = x; + goto out; + } + + max_bits = dht_bits_for (max); + + hi_mask = ~(PRESENT_MASK >> (max_bits + 1)); + + if (x & hi_mask) { + /* HUGE d_off */ + off_mask = MASK << max_bits; + y = TOP_BIT | ((x >> SHIFT_BITS) & off_mask) | cnt; + } else { + /* small d_off */ + y = ((x * max) + cnt); + } out: if (y_p) @@ -135,16 +191,38 @@ dht_deitransform (xlator_t *this, uint64_t y, xlator_t **subvol_p, int max = 0; uint64_t x = 0; xlator_t *subvol = 0; + int max_bits = 0; + uint64_t off_mask = 0; + uint64_t host_mask = 0; if (!this->private) - goto out; + return -1; conf = this->private; max = conf->subvolume_cnt; - cnt = y % max; - x = y / max; + if (max == 1) { + x = y; + cnt = 0; + goto out; + } + + if (y & TOP_BIT) { + /* HUGE d_off */ + max_bits = dht_bits_for (max); + off_mask = (MASK << max_bits); + host_mask = ~(off_mask); + + x = ((y & ~TOP_BIT) & off_mask) << SHIFT_BITS; + + cnt = y & host_mask; + } else { + /* small d_off */ + cnt = y % max; + x = y / max; + } +out: subvol = conf->subvolumes[cnt]; if (subvol_p) @@ -153,7 +231,6 @@ dht_deitransform (xlator_t *this, uint64_t y, xlator_t **subvol_p, if (x_p) *x_p = x; -out: return 0; } |