| 1 | // SPDX-License-Identifier: GPL-3.0-or-later |
| 2 | |
| 3 | //go:build linux |
| 4 | |
| 5 | package dmcache |
| 6 | |
| 7 | import ( |
| 8 | "bufio" |
| 9 | "bytes" |
| 10 | "errors" |
| 11 | "fmt" |
| 12 | "strconv" |
| 13 | "strings" |
| 14 | ) |
| 15 | |
| 16 | type dmCacheDevice struct { |
| 17 | name string |
| 18 | metaBlockSizeSectors int64 |
| 19 | metaUsedBlocks int64 |
| 20 | metaTotalBlocks int64 |
| 21 | cacheBlockSizeSectors int64 |
| 22 | cacheUsedBlocks int64 |
| 23 | cacheTotalBlocks int64 |
| 24 | readHits int64 |
| 25 | readMisses int64 |
| 26 | writeHits int64 |
| 27 | writeMisses int64 |
| 28 | demotionsBlocks int64 |
| 29 | promotionsBlocks int64 |
| 30 | dirtyBlocks int64 |
| 31 | } |
| 32 | |
| 33 | func (c *Collector) collect() (map[string]int64, error) { |
| 34 | bs, err := c.exec.cacheStatus() |
| 35 | if err != nil { |
| 36 | return nil, err |
| 37 | } |
| 38 | |
| 39 | mx := make(map[string]int64) |
| 40 | |
| 41 | if err := c.collectCacheStatus(mx, bs); err != nil { |
| 42 | return nil, err |
| 43 | } |
| 44 | |
| 45 | return mx, nil |
| 46 | } |
| 47 | |
| 48 | func (c *Collector) collectCacheStatus(mx map[string]int64, data []byte) error { |
| 49 | var devices []*dmCacheDevice |
| 50 | |
| 51 | sc := bufio.NewScanner(bytes.NewReader(data)) |
| 52 | |
| 53 | for sc.Scan() { |
| 54 | line := strings.TrimSpace(sc.Text()) |
| 55 | if line == "" { |
| 56 | continue |
| 57 | } |
| 58 | |
| 59 | dev, err := parseDmsetupStatusLine(line) |
| 60 | if err != nil { |
| 61 | return fmt.Errorf("malformed dmsetup status line: %v ('%s')", err, line) |
| 62 | } |
| 63 | |
| 64 | devices = append(devices, dev) |
| 65 | } |
| 66 | |
| 67 | seen := make(map[string]bool) |
| 68 | |
| 69 | for _, dev := range devices { |
| 70 | seen[dev.name] = true |
| 71 | |
| 72 | if !c.devices[dev.name] { |
| 73 | c.devices[dev.name] = true |
| 74 | c.addDeviceCharts(dev.name) |
| 75 | } |
| 76 | |
| 77 | px := fmt.Sprintf("dmcache_device_%s_", dev.name) |
| 78 | |
| 79 | const sectorSize = 512 |
| 80 | metaMul := dev.metaBlockSizeSectors * sectorSize |
| 81 | cacheMul := dev.cacheBlockSizeSectors * sectorSize |
| 82 | |
| 83 | mx[px+"metadata_free_bytes"] = (dev.metaTotalBlocks - dev.metaUsedBlocks) * metaMul |
| 84 | mx[px+"metadata_used_bytes"] = dev.metaUsedBlocks * metaMul |
| 85 | mx[px+"cache_free_bytes"] = (dev.cacheTotalBlocks - dev.cacheUsedBlocks) * cacheMul |
| 86 | mx[px+"cache_used_bytes"] = dev.cacheUsedBlocks * cacheMul |
| 87 | mx[px+"read_hits"] = dev.readHits |
| 88 | mx[px+"read_misses"] = dev.readMisses |
| 89 | mx[px+"write_hits"] = dev.writeHits |
| 90 | mx[px+"write_misses"] = dev.writeMisses |
| 91 | mx[px+"demotions_bytes"] = dev.demotionsBlocks * cacheMul |
| 92 | mx[px+"promotions_bytes"] = dev.promotionsBlocks * cacheMul |
| 93 | mx[px+"dirty_bytes"] = dev.dirtyBlocks * cacheMul |
| 94 | } |
| 95 | |
| 96 | for dev := range c.devices { |
| 97 | if !seen[dev] { |
| 98 | delete(c.devices, dev) |
| 99 | c.removeDeviceCharts(dev) |
| 100 | } |
| 101 | } |
| 102 | |
| 103 | if len(devices) == 0 { |
| 104 | return errors.New("no dm-cache devices found") |
| 105 | } |
| 106 | |
| 107 | return nil |
| 108 | } |
| 109 | |
| 110 | func parseDmsetupStatusLine(line string) (*dmCacheDevice, error) { |
| 111 | // https://www.kernel.org/doc/html/next/admin-guide/device-mapper/cache.html#status |
| 112 | |
| 113 | parts := strings.Fields(line) |
| 114 | if len(parts) < 15 { |
| 115 | return nil, fmt.Errorf("want at least 15 fields, got %d", len(parts)) |
| 116 | } |
| 117 | |
| 118 | var dev dmCacheDevice |
| 119 | var err error |
| 120 | |
| 121 | for i, s := range parts { |
| 122 | switch i { |
| 123 | case 0: |
| 124 | dev.name = strings.TrimSuffix(parts[0], ":") |
| 125 | case 4: |
| 126 | dev.metaBlockSizeSectors, err = parseInt(s) |
| 127 | case 5: |
| 128 | dev.metaUsedBlocks, dev.metaTotalBlocks, err = parseUsedTotalBlocks(s) |
| 129 | case 6: |
| 130 | dev.cacheBlockSizeSectors, err = parseInt(s) |
| 131 | case 7: |
| 132 | dev.cacheUsedBlocks, dev.cacheTotalBlocks, err = parseUsedTotalBlocks(s) |
| 133 | case 8: |
| 134 | dev.readHits, err = parseInt(s) |
| 135 | case 9: |
| 136 | dev.readMisses, err = parseInt(s) |
| 137 | case 10: |
| 138 | dev.writeHits, err = parseInt(s) |
| 139 | case 11: |
| 140 | dev.writeMisses, err = parseInt(s) |
| 141 | case 12: |
| 142 | dev.demotionsBlocks, err = parseInt(s) |
| 143 | case 13: |
| 144 | dev.promotionsBlocks, err = parseInt(s) |
| 145 | case 14: |
| 146 | dev.dirtyBlocks, err = parseInt(s) |
| 147 | } |
| 148 | |
| 149 | if err != nil { |
| 150 | return nil, fmt.Errorf("failed to parse %d field '%s': %v", i, s, err) |
| 151 | } |
| 152 | } |
| 153 | |
| 154 | return &dev, nil |
| 155 | } |
| 156 | |
| 157 | func parseUsedTotalBlocks(info string) (int64, int64, error) { |
| 158 | parts := strings.Split(info, "/") |
| 159 | if len(parts) != 2 { |
| 160 | return 0, 0, errors.New("expected used/total") |
| 161 | } |
| 162 | used, err := parseInt(parts[0]) |
| 163 | if err != nil { |
| 164 | return 0, 0, err |
| 165 | } |
| 166 | total, err := parseInt(parts[1]) |
| 167 | if err != nil { |
| 168 | return 0, 0, err |
| 169 | } |
| 170 | return used, total, nil |
| 171 | } |
| 172 | |
| 173 | func parseInt(s string) (int64, error) { |
| 174 | return strconv.ParseInt(s, 10, 64) |
| 175 | } |