@@ -22,7 +22,119 @@ use with caution.
SUBCOMMAND
----------
-Nothing yet
+*enable* [options] <path>::
+Enable in-band de-duplication for a filesystem.
++
+`Options`
++
+-f|--force::::
+Force 'enable' command to be exected.
+Will skip memory limit check and allow 'enable' to be executed even in-band
+de-duplication is already enabled.
++
+NOTE: If re-enable dedupe with '-f' option, any unspecified parameter will be
+reset to its default value.
+
+-s|--storage-backend <BACKEND>::::
+Specify de-duplication hash storage backend.
+Only 'inmemory' backend is supported yet.
+If not specified, default value is 'inmemory'.
++
+Refer to *BACKENDS* sector for more information.
+
+-b|--blocksize <BLOCKSIZE>::::
+Specify dedupe block size.
+Supported values are power of 2 from '16K' to '8M'.
+Default value is '128K'.
++
+Refer to *BLOCKSIZE* sector for more information.
+
+-a|--hash-algorithm <HASH>::::
+Specify hash algorithm.
+Only 'sha256' is supported yet.
+
+-l|--limit-hash <LIMIT>::::
+Specify maximum number of hashes stored in memory.
+Only works for 'inmemory' backend.
+Conflicts with '-m' option.
++
+Only positive values are valid.
+Default value is '32K'.
+
+-m|--limit-memory <LIMIT>::::
+Specify maximum memory used for hashes.
+Only works for 'inmemory' backend.
+Conflicts with '-l' option.
++
+Only value larger than or equal to '1024' is valid.
+No default value.
++
+NOTE: Memory limit will be rounded down to kernel internal hash size,
+so the memory limit shown in 'btrfs dedupe status' may be different
+from the <LIMIT>.
+
+WARNING: Too large value for '-l' or '-m' will easily trigger OOM.
+Please use with caution according to system memory.
+
+NOTE: In-band de-duplication is not compactible with compression yet.
+And compression has higher priority than in-band de-duplication, means if
+compression and de-duplication is enabled at the same time, only compression
+will work.
+
+BACKENDS
+--------
+Btrfs in-band de-duplication will support different storage backends, with
+different use case and features.
+
+In-memory backend::
+This backend provides backward-compatibility, and more fine-tuning options.
+But hash pool is non-persistent and may exhaust kernel memory if not setup
+properly.
++
+This backend can be used on old btrfs(without '-O dedupe' mkfs option).
+When used on old btrfs, this backend needs to be enabled manually after mount.
++
+Designed for fast hash search speed, in-memory backend will keep all dedupe
+hashes in memory. (Although overall performance is still much the same with
+'ondisk' backend if all 'ondisk' hash can be cached in memory)
++
+And only keeps limited number of hash in memory to avoid exhausting memory.
+Hashes over the limit will be dropped following Last-Recent-Use behavior.
+So this backend has a consistent overhead for given limit but can\'t ensure
+all duplicated blocks will be de-duplicated.
++
+After umount and mount, in-memory backend need to refill its hash pool.
+
+On-disk backend::
+This backend provides persistent hash pool, with more smart memory management
+for hash pool.
+But it\'s not backward-compatible, meaning it must be used with '-O dedupe' mkfs
+option and older kernel can\'t mount it read-write.
++
+Designed for de-duplication rate, hash pool is stored as btrfs B+ tree on disk.
+This behavior may cause extra disk IO for hash search under high memory
+pressure.
++
+After umount and mount, on-disk backend still has its hash on disk, no need to
+refill its dedupe hash pool.
+
+Currently, only 'inmemory' backend is supported in btrfs-progs.
+
+DEDUPE BLOCK SIZE
+----------------
+In-band de-duplication is done at dedupe block size.
+Any data smaller than dedupe block size won\'t go through in-band
+de-duplication.
+
+And dedupe block size affects dedupe rate and fragmentation heavily.
+
+Smaller block size will cause more fragments, but higher dedupe rate.
+
+Larger block size will cause less fragments, but lower dedupe rate.
+
+In-band de-duplication rate is highly related to the workload pattern.
+So it\'s highly recommended to align dedupe block size to the workload
+block size to make full use of de-duplication.
EXIT STATUS
-----------
@@ -29,7 +29,7 @@ _btrfs()
local cmd=${words[1]}
- commands='subvolume filesystem balance device scrub check rescue restore inspect-internal property send receive quota qgroup replace help version'
+ commands='subvolume filesystem balance device scrub check rescue restore inspect-internal property send receive quota qgroup replace dedupe help version'
commands_subvolume='create delete list snapshot find-new get-default set-default show sync'
commands_filesystem='defragment sync resize show df du label usage'
commands_balance='start pause cancel resume status'
@@ -41,6 +41,7 @@ _btrfs()
commands_quota='enable disable rescan'
commands_qgroup='assign remove create destroy show limit'
commands_replace='start status cancel'
+ commands_dedupe='enable'
if [[ "$cur" == -* && $cword -le 3 && "$cmd" != "help" ]]; then
COMPREPLY=( $( compgen -W '--help' -- "$cur" ) )
@@ -97,6 +98,9 @@ _btrfs()
replace)
opts="$commands_replace"
;;
+ dedupe)
+ opts="$commands_dedupe"
+ ;;
help)
opts="--full"
;;
@@ -6,11 +6,13 @@
#include <getopt.h>
#include <unistd.h>
#include <sys/ioctl.h>
+#include <sys/sysinfo.h>
#include "ctree.h"
#include "ioctl.h"
#include "commands.h"
+#include "help.h"
#include "utils.h"
#include "kerncompat.h"
#include "dedupe-ib.h"
@@ -23,8 +25,247 @@ static const char * const dedupe_ib_cmd_group_usage[] = {
static const char dedupe_ib_cmd_group_info[] =
"manage inband(write time) de-duplication";
+static const char * const cmd_dedupe_ib_enable_usage[] = {
+ "btrfs dedupe-inband enable [options] <path>",
+ "Enable in-band(write time) de-duplication of a btrfs.",
+ "",
+ "-s|--storage-backend <BACKEND>",
+ " specify dedupe hash storage backend",
+ " supported backend: 'inmemory'",
+ "-b|--blocksize <BLOCKSIZE>",
+ " specify dedupe block size",
+ " default value is 128K",
+ "-a|--hash-algorithm <HASH>",
+ " specify hash algorithm",
+ " only 'sha256' is supported yet",
+ "-l|--limit-hash <LIMIT>",
+ " specify maximum number of hashes stored in memory",
+ " only for 'inmemory' backend",
+ " positive value is valid, default value is 32K",
+ "-m|--limit-mem <LIMIT>",
+ " specify maximum memory used for hashes",
+ " only for 'inmemory' backend",
+ " value larger than or equal to 1024 is valid, no default",
+ " only one of '-m' and '-l' is allowed",
+ "-f|--force",
+ " force enable command to be executed",
+ " will skip some memory limit check",
+ " also without this flag enable command is not allowed to be",
+ " executed if dedupe is already enabled",
+ " note: unspecified parameter will be reset to default value",
+ NULL
+};
+
+
+#define report_fatal_parameter(dargs, old, member, type, err_val, fmt) \
+({ \
+ if (dargs->member != old->member && \
+ dargs->member == (type)(err_val)) \
+ error("unsupported dedupe "#member": %"#fmt"", \
+ old->member); \
+ (dargs->member != old->member && \
+ dargs->member == (type)(err_val)); \
+})
+
+#define report_option_parameter(dargs, old, member, type, err_val, fmt) \
+do { \
+ if (dargs->member != old->member && \
+ dargs->member == (type)(err_val)) \
+ warning( \
+ "unsupported optional "#member": %"#fmt", continue", \
+ old->member); \
+} while (0)
+
+static void report_parameter_error(struct btrfs_ioctl_dedupe_args *dargs,
+ struct btrfs_ioctl_dedupe_args *old)
+{
+ if (dargs->flags == (u8)-1) {
+ if (dargs->status == 1 &&
+ old->cmd == BTRFS_DEDUPE_CTL_ENABLE &&
+ !(old->flags & BTRFS_DEDUPE_FLAG_FORCE)) {
+ error("can't re-enable dedupe without --force");
+ return;
+ }
+ report_option_parameter(dargs, old, flags, u8, -1, x);
+ }
+ if (report_fatal_parameter(dargs, old, cmd, u16, -1, u) ||
+ report_fatal_parameter(dargs, old, blocksize, u64, -1, llu) ||
+ report_fatal_parameter(dargs, old, backend, u16, -1, u) ||
+ report_fatal_parameter(dargs, old, hash_algo, u16, -1, u))
+ return;
+
+ if (dargs->limit_nr == 0 && dargs->limit_mem == 0)
+ error(
+ "unsupported dedupe limit combination: nr: %llu, mem: %llu",
+ old->limit_nr, old->limit_mem);
+}
+
+static int cmd_dedupe_ib_enable(int argc, char **argv)
+{
+ int ret;
+ int fd = -1;
+ char *path;
+ u64 blocksize = BTRFS_DEDUPE_BLOCKSIZE_DEFAULT;
+ u16 hash_algo = BTRFS_DEDUPE_HASH_SHA256;
+ u16 backend = BTRFS_DEDUPE_BACKEND_INMEMORY;
+ u64 limit_nr = 0;
+ u64 limit_mem = 0;
+ u64 sys_mem = 0;
+ int force = 0;
+ struct btrfs_ioctl_dedupe_args dargs;
+ struct btrfs_ioctl_dedupe_args backup;
+ struct sysinfo info;
+ DIR *dirstream = NULL;
+
+ while (1) {
+ int c;
+ static const struct option long_options[] = {
+ { "storage-backend", required_argument, NULL, 's'},
+ { "blocksize", required_argument, NULL, 'b'},
+ { "hash-algorithm", required_argument, NULL, 'a'},
+ { "limit-hash", required_argument, NULL, 'l'},
+ { "limit-memory", required_argument, NULL, 'm'},
+ { "force", required_argument, NULL, 'f'},
+ { NULL, 0, NULL, 0}
+ };
+
+ c = getopt_long(argc, argv, "s:b:a:l:m:", long_options, NULL);
+ if (c < 0)
+ break;
+ switch (c) {
+ case 's':
+ if (!strcasecmp("inmemory", optarg))
+ backend = BTRFS_DEDUPE_BACKEND_INMEMORY;
+ else {
+ error("unsupported dedupe backend: %s", optarg);
+ exit(1);
+ }
+ break;
+ case 'b':
+ blocksize = parse_size(optarg);
+ break;
+ case 'a':
+ if (strcmp("sha256", optarg)) {
+ error("unsupported dedupe hash algorithm: %s",
+ optarg);
+ return 1;
+ }
+ break;
+ case 'l':
+ limit_nr = parse_size(optarg);
+ if (limit_nr == 0) {
+ error("limit should be larger than 0");
+ return 1;
+ }
+ break;
+ case 'm':
+ limit_mem = parse_size(optarg);
+ /*
+ * Make sure at least one hash is allocated
+ * 1024 should be good enough though.
+ */
+ if (limit_mem < 1024) {
+ error(
+ "memory limit should be larger than or equal to 1024");
+ return 1;
+ }
+ break;
+ case 'f':
+ force = 1;
+ break;
+ default:
+ usage(cmd_dedupe_ib_enable_usage);
+ return 1;
+ }
+ }
+
+ path = argv[optind];
+ if (check_argc_exact(argc - optind, 1))
+ usage(cmd_dedupe_ib_enable_usage);
+
+ /* Validation check */
+ if (!is_power_of_2(blocksize) ||
+ blocksize > BTRFS_DEDUPE_BLOCKSIZE_MAX ||
+ blocksize < BTRFS_DEDUPE_BLOCKSIZE_MIN) {
+ error(
+ "invalid dedupe blocksize: %llu, not in range [%u,%u] or power of 2",
+ blocksize, BTRFS_DEDUPE_BLOCKSIZE_MIN,
+ BTRFS_DEDUPE_BLOCKSIZE_MAX);
+ return 1;
+ }
+ if ((limit_nr || limit_mem) &&
+ backend != BTRFS_DEDUPE_BACKEND_INMEMORY) {
+ error("limit is only valid for 'inmemory' backend");
+ return 1;
+ }
+ if (limit_nr && limit_mem) {
+ error(
+ "limit-memory and limit-hash can't be given at the same time");
+ return 1;
+ }
+
+ ret = sysinfo(&info);
+ if (ret < 0)
+ warning("failed to determine system total ram size: %s",
+ strerror(errno));
+ else
+ sys_mem = info.totalram;
+
+ /*
+ * TODO: Add check for limit_nr against current system
+ * memory to avoid wrongly set limit.
+ */
+ if (!force && limit_mem && sys_mem && sys_mem < limit_mem * 4) {
+ dargs.limit_mem = limit_mem;
+ goto mem_check;
+ }
+
+ fd = open_file_or_dir(path, &dirstream);
+ if (fd < 0) {
+ error("failed to open file or directory: %s", path);
+ return 1;
+ }
+ memset(&dargs, -1, sizeof(dargs));
+ dargs.cmd = BTRFS_DEDUPE_CTL_ENABLE;
+ dargs.blocksize = blocksize;
+ dargs.hash_algo = hash_algo;
+ dargs.limit_nr = limit_nr;
+ dargs.limit_mem = limit_mem;
+ dargs.backend = backend;
+ if (force)
+ dargs.flags |= BTRFS_DEDUPE_FLAG_FORCE;
+ else
+ dargs.flags = 0;
+
+ memcpy(&backup, &dargs, sizeof(dargs));
+ ret = ioctl(fd, BTRFS_IOC_DEDUPE_CTL, &dargs);
+ if (ret < 0) {
+ error("failed to enable inband deduplication: %s",
+ strerror(errno));
+ report_parameter_error(&dargs, &backup);
+ ret = 1;
+ goto out;
+ }
+ ret = 0;
+mem_check:
+ if (!force && dargs.limit_mem > sys_mem / 4) {
+ ret = 1;
+ error(
+ "memory limit %llu is too large compared to system memory: %llu",
+ limit_mem, sys_mem);
+ error("recommened memory limit is no more than %llu",
+ sys_mem / 4);
+ error("use --force option if you know what you are doing");
+ }
+out:
+ close_file_or_dir(fd, dirstream);
+ return ret;
+}
+
const struct cmd_group dedupe_ib_cmd_group = {
dedupe_ib_cmd_group_usage, dedupe_ib_cmd_group_info, {
+ { "enable", cmd_dedupe_ib_enable, cmd_dedupe_ib_enable_usage,
+ NULL, 0},
NULL_CMD_STRUCT
}
};
@@ -856,6 +856,8 @@ static inline char *btrfs_err_str(enum btrfs_err_code err_code)
struct btrfs_ioctl_dev_replace_args)
#define BTRFS_IOC_FILE_EXTENT_SAME _IOWR(BTRFS_IOCTL_MAGIC, 54, \
struct btrfs_ioctl_same_args)
+#define BTRFS_IOC_DEDUPE_CTL _IOWR(BTRFS_IOCTL_MAGIC, 55, \
+ struct btrfs_ioctl_dedupe_args)
#define BTRFS_IOC_GET_FEATURES _IOR(BTRFS_IOCTL_MAGIC, 57, \
struct btrfs_ioctl_feature_flags)
#define BTRFS_IOC_SET_FEATURES _IOW(BTRFS_IOCTL_MAGIC, 57, \