|
| 1 | +/* |
| 2 | + * readahead.c -- Prefetch filesystem metadata to speed up fsck. |
| 3 | + * |
| 4 | + * Copyright (C) 2014 Oracle. |
| 5 | + * |
| 6 | + * %Begin-Header% |
| 7 | + * This file may be redistributed under the terms of the GNU Library |
| 8 | + * General Public License, version 2. |
| 9 | + * %End-Header% |
| 10 | + */ |
| 11 | + |
| 12 | +#include "config.h" |
| 13 | +#include <string.h> |
| 14 | + |
| 15 | +#include "e2fsck.h" |
| 16 | + |
| 17 | +#undef DEBUG |
| 18 | + |
| 19 | +#ifdef DEBUG |
| 20 | +# define dbg_printf(f, a...) do {printf(f, ## a); fflush(stdout); } while (0) |
| 21 | +#else |
| 22 | +# define dbg_printf(f, a...) |
| 23 | +#endif |
| 24 | + |
| 25 | +struct read_dblist { |
| 26 | + errcode_t err; |
| 27 | + blk64_t run_start; |
| 28 | + blk64_t run_len; |
| 29 | + int flags; |
| 30 | +}; |
| 31 | + |
| 32 | +static int readahead_dir_block(ext2_filsys fs, struct ext2_db_entry2 *db, |
| 33 | + void *priv_data) |
| 34 | +{ |
| 35 | + struct read_dblist *pr = priv_data; |
| 36 | + e2_blkcnt_t count = (pr->flags & E2FSCK_RA_DBLIST_IGNORE_BLOCKCNT ? |
| 37 | + 1 : db->blockcnt); |
| 38 | + |
| 39 | + if (!pr->run_len || db->blk != pr->run_start + pr->run_len) { |
| 40 | + if (pr->run_len) { |
| 41 | + pr->err = io_channel_cache_readahead(fs->io, |
| 42 | + pr->run_start, |
| 43 | + pr->run_len); |
| 44 | + dbg_printf("readahead start=%llu len=%llu err=%d\n", |
| 45 | + pr->run_start, pr->run_len, |
| 46 | + (int)pr->err); |
| 47 | + } |
| 48 | + pr->run_start = db->blk; |
| 49 | + pr->run_len = 0; |
| 50 | + } |
| 51 | + pr->run_len += count; |
| 52 | + |
| 53 | + return pr->err ? DBLIST_ABORT : 0; |
| 54 | +} |
| 55 | + |
| 56 | +errcode_t e2fsck_readahead_dblist(ext2_filsys fs, int flags, |
| 57 | + ext2_dblist dblist, |
| 58 | + unsigned long long start, |
| 59 | + unsigned long long count) |
| 60 | +{ |
| 61 | + errcode_t err; |
| 62 | + struct read_dblist pr; |
| 63 | + |
| 64 | + dbg_printf("%s: flags=0x%x\n", __func__, flags); |
| 65 | + if (flags & ~E2FSCK_RA_DBLIST_ALL_FLAGS) |
| 66 | + return EXT2_ET_INVALID_ARGUMENT; |
| 67 | + |
| 68 | + memset(&pr, 0, sizeof(pr)); |
| 69 | + pr.flags = flags; |
| 70 | + err = ext2fs_dblist_iterate3(dblist, readahead_dir_block, start, |
| 71 | + count, &pr); |
| 72 | + if (pr.err) |
| 73 | + return pr.err; |
| 74 | + if (err) |
| 75 | + return err; |
| 76 | + |
| 77 | + if (pr.run_len) |
| 78 | + err = io_channel_cache_readahead(fs->io, pr.run_start, |
| 79 | + pr.run_len); |
| 80 | + |
| 81 | + return err; |
| 82 | +} |
| 83 | + |
| 84 | +static errcode_t e2fsck_readahead_bitmap(ext2_filsys fs, |
| 85 | + ext2fs_block_bitmap ra_map) |
| 86 | +{ |
| 87 | + blk64_t start, end, out; |
| 88 | + errcode_t err; |
| 89 | + |
| 90 | + start = 1; |
| 91 | + end = ext2fs_blocks_count(fs->super) - 1; |
| 92 | + |
| 93 | + err = ext2fs_find_first_set_block_bitmap2(ra_map, start, end, &out); |
| 94 | + while (err == 0) { |
| 95 | + start = out; |
| 96 | + err = ext2fs_find_first_zero_block_bitmap2(ra_map, start, end, |
| 97 | + &out); |
| 98 | + if (err == ENOENT) { |
| 99 | + out = end; |
| 100 | + err = 0; |
| 101 | + } else if (err) |
| 102 | + break; |
| 103 | + |
| 104 | + err = io_channel_cache_readahead(fs->io, start, out - start); |
| 105 | + if (err) |
| 106 | + break; |
| 107 | + start = out; |
| 108 | + err = ext2fs_find_first_set_block_bitmap2(ra_map, start, end, |
| 109 | + &out); |
| 110 | + } |
| 111 | + |
| 112 | + if (err == ENOENT) |
| 113 | + err = 0; |
| 114 | + |
| 115 | + return err; |
| 116 | +} |
| 117 | + |
| 118 | +/* Try not to spew bitmap range errors for readahead */ |
| 119 | +static errcode_t mark_bmap_range(ext2fs_block_bitmap map, |
| 120 | + blk64_t blk, unsigned int num) |
| 121 | +{ |
| 122 | + if (blk >= ext2fs_get_generic_bmap_start(map) && |
| 123 | + blk + num <= ext2fs_get_generic_bmap_end(map)) |
| 124 | + ext2fs_mark_block_bitmap_range2(map, blk, num); |
| 125 | + else |
| 126 | + return EXT2_ET_INVALID_ARGUMENT; |
| 127 | + return 0; |
| 128 | +} |
| 129 | + |
| 130 | +static errcode_t mark_bmap(ext2fs_block_bitmap map, blk64_t blk) |
| 131 | +{ |
| 132 | + if (blk >= ext2fs_get_generic_bmap_start(map) && |
| 133 | + blk <= ext2fs_get_generic_bmap_end(map)) |
| 134 | + ext2fs_mark_block_bitmap2(map, blk); |
| 135 | + else |
| 136 | + return EXT2_ET_INVALID_ARGUMENT; |
| 137 | + return 0; |
| 138 | +} |
| 139 | + |
| 140 | +errcode_t e2fsck_readahead(ext2_filsys fs, int flags, dgrp_t start, |
| 141 | + dgrp_t ngroups) |
| 142 | +{ |
| 143 | + blk64_t super, old_gdt, new_gdt; |
| 144 | + blk_t blocks; |
| 145 | + dgrp_t i; |
| 146 | + ext2fs_block_bitmap ra_map = NULL; |
| 147 | + dgrp_t end = start + ngroups; |
| 148 | + errcode_t err = 0; |
| 149 | + |
| 150 | + dbg_printf("%s: flags=0x%x start=%d groups=%d\n", __func__, flags, |
| 151 | + start, ngroups); |
| 152 | + if (flags & ~E2FSCK_READA_ALL_FLAGS) |
| 153 | + return EXT2_ET_INVALID_ARGUMENT; |
| 154 | + |
| 155 | + if (end > fs->group_desc_count) |
| 156 | + end = fs->group_desc_count; |
| 157 | + |
| 158 | + if (flags == 0) |
| 159 | + return 0; |
| 160 | + |
| 161 | + err = ext2fs_allocate_block_bitmap(fs, "readahead bitmap", |
| 162 | + &ra_map); |
| 163 | + if (err) |
| 164 | + return err; |
| 165 | + |
| 166 | + for (i = start; i < end; i++) { |
| 167 | + err = ext2fs_super_and_bgd_loc2(fs, i, &super, &old_gdt, |
| 168 | + &new_gdt, &blocks); |
| 169 | + if (err) |
| 170 | + break; |
| 171 | + |
| 172 | + if (flags & E2FSCK_READA_SUPER) { |
| 173 | + err = mark_bmap(ra_map, super); |
| 174 | + if (err) |
| 175 | + break; |
| 176 | + } |
| 177 | + |
| 178 | + if (flags & E2FSCK_READA_GDT) { |
| 179 | + err = mark_bmap_range(ra_map, |
| 180 | + old_gdt ? old_gdt : new_gdt, |
| 181 | + blocks); |
| 182 | + if (err) |
| 183 | + break; |
| 184 | + } |
| 185 | + |
| 186 | + if ((flags & E2FSCK_READA_BBITMAP) && |
| 187 | + !ext2fs_bg_flags_test(fs, i, EXT2_BG_BLOCK_UNINIT) && |
| 188 | + ext2fs_bg_free_blocks_count(fs, i) < |
| 189 | + fs->super->s_blocks_per_group) { |
| 190 | + super = ext2fs_block_bitmap_loc(fs, i); |
| 191 | + err = mark_bmap(ra_map, super); |
| 192 | + if (err) |
| 193 | + break; |
| 194 | + } |
| 195 | + |
| 196 | + if ((flags & E2FSCK_READA_IBITMAP) && |
| 197 | + !ext2fs_bg_flags_test(fs, i, EXT2_BG_INODE_UNINIT) && |
| 198 | + ext2fs_bg_free_inodes_count(fs, i) < |
| 199 | + fs->super->s_inodes_per_group) { |
| 200 | + super = ext2fs_inode_bitmap_loc(fs, i); |
| 201 | + err = mark_bmap(ra_map, super); |
| 202 | + if (err) |
| 203 | + break; |
| 204 | + } |
| 205 | + |
| 206 | + if ((flags & E2FSCK_READA_ITABLE) && |
| 207 | + ext2fs_bg_free_inodes_count(fs, i) < |
| 208 | + fs->super->s_inodes_per_group) { |
| 209 | + super = ext2fs_inode_table_loc(fs, i); |
| 210 | + blocks = fs->inode_blocks_per_group - |
| 211 | + (ext2fs_bg_itable_unused(fs, i) * |
| 212 | + EXT2_INODE_SIZE(fs->super) / fs->blocksize); |
| 213 | + err = mark_bmap_range(ra_map, super, blocks); |
| 214 | + if (err) |
| 215 | + break; |
| 216 | + } |
| 217 | + } |
| 218 | + |
| 219 | + if (!err) |
| 220 | + err = e2fsck_readahead_bitmap(fs, ra_map); |
| 221 | + |
| 222 | + ext2fs_free_block_bitmap(ra_map); |
| 223 | + return err; |
| 224 | +} |
| 225 | + |
| 226 | +int e2fsck_can_readahead(ext2_filsys fs) |
| 227 | +{ |
| 228 | + errcode_t err; |
| 229 | + |
| 230 | + err = io_channel_cache_readahead(fs->io, 0, 1); |
| 231 | + dbg_printf("%s: supp=%d\n", __func__, err != EXT2_ET_OP_NOT_SUPPORTED); |
| 232 | + return err != EXT2_ET_OP_NOT_SUPPORTED; |
| 233 | +} |
| 234 | + |
| 235 | +unsigned long long e2fsck_guess_readahead(ext2_filsys fs) |
| 236 | +{ |
| 237 | + unsigned long long guess; |
| 238 | + |
| 239 | + /* |
| 240 | + * The optimal readahead sizes were experimentally determined by |
| 241 | + * djwong in August 2014. Setting the RA size to two block groups' |
| 242 | + * worth of inode table blocks seems to yield the largest reductions |
| 243 | + * in e2fsck runtime. |
| 244 | + */ |
| 245 | + guess = 2 * fs->blocksize * fs->inode_blocks_per_group; |
| 246 | + |
| 247 | + /* Disable RA if it'd use more 1/50th of RAM. */ |
| 248 | + if (get_memory_size() > (guess * 50)) |
| 249 | + return guess / 1024; |
| 250 | + |
| 251 | + return 0; |
| 252 | +} |
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