Index: btrfs-progs-v4.3/Documentation/btrfs-balance.asciidoc =================================================================== --- btrfs-progs-v4.3.orig/Documentation/btrfs-balance.asciidoc +++ btrfs-progs-v4.3/Documentation/btrfs-balance.asciidoc @@ -67,6 +67,12 @@ resume interrupted balance start the balance operation according to the specified filters, no filters will rewrite the entire filesystem. The process runs in the foreground. + +NOTE: the balance command without filters will basically rewrite everything +int the filesystem. The run time is potentially very long, depending on the +filesystem size. To prevent starting a full balance by accident, the user is +warned and has a few seconds to cancel the operation before it starts. The +warning and delay can be skipped with '--full-balance' option. ++ `Options` + -d[]:::: Index: btrfs-progs-v4.3/cmds-balance.c =================================================================== --- btrfs-progs-v4.3.orig/cmds-balance.c +++ btrfs-progs-v4.3/cmds-balance.c @@ -383,8 +383,13 @@ static int do_balance_v1(int fd) return ret; } +enum { + BALANCE_START_FILTERS = 1 << 0, + BALANCE_START_NOWARN = 1 << 1 +}; + static int do_balance(const char *path, struct btrfs_ioctl_balance_args *args, - int nofilters) + unsigned flags) { int fd; int ret; @@ -395,6 +400,24 @@ static int do_balance(const char *path, if (fd < 0) return 1; + if (!(flags & BALANCE_START_FILTERS) && !(flags & BALANCE_START_NOWARN)) { + int delay = 10; + + printf("WARNING:\n\n"); + printf("\tFull balance without filters requested. This operation is very\n"); + printf("\tintense and takes potentially very long. It is recommended to\n"); + printf("\tuse the balance filters to narrow down the balanced data.\n"); + printf("\tUse 'btrfs balance start --full-balance' option to skip this\n"); + printf("\twarning. The operation printf will start in %d seconds.\n", delay); + printf("\tUse Ctrl-C to stop it.\n"); + while (delay) { + sleep(1); + printf("%2d", delay--); + fflush(stdout); + } + printf("\nStarting balance without any filters.\n"); + } + ret = ioctl(fd, BTRFS_IOC_BALANCE_V2, args); e = errno; @@ -404,7 +427,7 @@ static int do_balance(const char *path, * old one. But, the old one doesn't know any filters, so * don't fall back if they tried to use the fancy new things */ - if (e == ENOTTY && nofilters) { + if (e == ENOTTY && !(flags & BALANCE_START_FILTERS)) { ret = do_balance_v1(fd); if (ret == 0) goto out; @@ -444,13 +467,16 @@ static const char * const cmd_balance_st "passed all filters in a comma-separated list of filters for a", "particular chunk type. If filter list is not given balance all", "chunks of that type. In case none of the -d, -m or -s options is", - "given balance all chunks in a filesystem.", + "given balance all chunks in a filesystem. This is potentially", + "long operation and the user is warned before this start, with", + "a delay to stop it.", "", "-d[filters] act on data chunks", "-m[filters] act on metadata chunks", "-s[filters] act on system chunks (only under -f)", "-v be verbose", "-f force reducing of metadata integrity", + "--full-balance do not print warning and do not delay start", NULL }; @@ -461,19 +487,22 @@ static int cmd_balance_start(int argc, c &args.meta, NULL }; int force = 0; int verbose = 0; - int nofilters = 1; + unsigned start_flags = 0; int i; memset(&args, 0, sizeof(args)); optind = 1; while (1) { + enum { GETOPT_VAL_FULL_BALANCE = 256 }; static const struct option longopts[] = { { "data", optional_argument, NULL, 'd'}, { "metadata", optional_argument, NULL, 'm' }, { "system", optional_argument, NULL, 's' }, { "force", no_argument, NULL, 'f' }, { "verbose", no_argument, NULL, 'v' }, + { "full-balance", no_argument, NULL, + GETOPT_VAL_FULL_BALANCE }, { NULL, 0, NULL, 0 } }; @@ -483,21 +512,21 @@ static int cmd_balance_start(int argc, c switch (opt) { case 'd': - nofilters = 0; + start_flags |= BALANCE_START_FILTERS; args.flags |= BTRFS_BALANCE_DATA; if (parse_filters(optarg, &args.data)) return 1; break; case 's': - nofilters = 0; + start_flags |= BALANCE_START_FILTERS; args.flags |= BTRFS_BALANCE_SYSTEM; if (parse_filters(optarg, &args.sys)) return 1; break; case 'm': - nofilters = 0; + start_flags |= BALANCE_START_FILTERS; args.flags |= BTRFS_BALANCE_METADATA; if (parse_filters(optarg, &args.meta)) @@ -509,6 +538,9 @@ static int cmd_balance_start(int argc, c case 'v': verbose = 1; break; + case GETOPT_VAL_FULL_BALANCE: + start_flags |= BALANCE_START_NOWARN; + break; default: usage(cmd_balance_start_usage); } @@ -534,7 +566,7 @@ static int cmd_balance_start(int argc, c sizeof(struct btrfs_balance_args)); } - if (nofilters) { + if (!(start_flags & BALANCE_START_FILTERS)) { /* relocate everything - no filters */ args.flags |= BTRFS_BALANCE_TYPE_MASK; } @@ -564,7 +596,7 @@ static int cmd_balance_start(int argc, c if (verbose) dump_ioctl_balance_args(&args); - return do_balance(argv[optind], &args, nofilters); + return do_balance(argv[optind], &args, start_flags); } static const char * const cmd_balance_pause_usage[] = { @@ -798,6 +830,16 @@ static int cmd_balance_status(int argc, return 1; } +static int cmd_balance_full(int argc, char **argv) +{ + struct btrfs_ioctl_balance_args args; + + memset(&args, 0, sizeof(args)); + args.flags |= BTRFS_BALANCE_TYPE_MASK; + + return do_balance(argv[1], &args, BALANCE_START_NOWARN); +} + static const char balance_cmd_group_info[] = "balance data accross devices, or change block groups using filters"; @@ -808,20 +850,21 @@ const struct cmd_group balance_cmd_group { "cancel", cmd_balance_cancel, cmd_balance_cancel_usage, NULL, 0 }, { "resume", cmd_balance_resume, cmd_balance_resume_usage, NULL, 0 }, { "status", cmd_balance_status, cmd_balance_status_usage, NULL, 0 }, + { "--full-balance", cmd_balance_full, NULL, NULL, 1 }, NULL_CMD_STRUCT } }; int cmd_balance(int argc, char **argv) { - if (argc == 2) { + if (argc == 2 && strcmp("start", argv[1]) != 0) { /* old 'btrfs filesystem balance ' syntax */ struct btrfs_ioctl_balance_args args; memset(&args, 0, sizeof(args)); args.flags |= BTRFS_BALANCE_TYPE_MASK; - return do_balance(argv[1], &args, 1); + return do_balance(argv[1], &args, 0); } return handle_command_group(&balance_cmd_group, argc, argv);