Opt_err,
};
- static const match_table_t tokens = {
- {Opt_acl, "acl"},
- {Opt_noacl, "noacl"},
- {Opt_clear_cache, "clear_cache"},
- {Opt_commit_interval, "commit=%u"},
- {Opt_compress, "compress"},
- {Opt_compress_type, "compress=%s"},
- {Opt_compress_force, "compress-force"},
- {Opt_compress_force_type, "compress-force=%s"},
- {Opt_degraded, "degraded"},
- {Opt_device, "device=%s"},
- {Opt_fatal_errors, "fatal_errors=%s"},
- {Opt_flushoncommit, "flushoncommit"},
- {Opt_noflushoncommit, "noflushoncommit"},
- {Opt_inode_cache, "inode_cache"},
- {Opt_noinode_cache, "noinode_cache"},
- {Opt_max_inline, "max_inline=%s"},
- {Opt_barrier, "barrier"},
- {Opt_nobarrier, "nobarrier"},
- {Opt_datacow, "datacow"},
- {Opt_nodatacow, "nodatacow"},
- {Opt_datasum, "datasum"},
- {Opt_nodatasum, "nodatasum"},
- {Opt_defrag, "autodefrag"},
- {Opt_nodefrag, "noautodefrag"},
- {Opt_discard, "discard"},
- {Opt_discard_mode, "discard=%s"},
- {Opt_nodiscard, "nodiscard"},
- {Opt_norecovery, "norecovery"},
- {Opt_ratio, "metadata_ratio=%u"},
- {Opt_rescan_uuid_tree, "rescan_uuid_tree"},
- {Opt_skip_balance, "skip_balance"},
- {Opt_space_cache, "space_cache"},
- {Opt_no_space_cache, "nospace_cache"},
- {Opt_space_cache_version, "space_cache=%s"},
- {Opt_ssd, "ssd"},
- {Opt_nossd, "nossd"},
- {Opt_ssd_spread, "ssd_spread"},
- {Opt_nossd_spread, "nossd_spread"},
- {Opt_subvol, "subvol=%s"},
- {Opt_subvol_empty, "subvol="},
- {Opt_subvolid, "subvolid=%s"},
- {Opt_thread_pool, "thread_pool=%u"},
- {Opt_treelog, "treelog"},
- {Opt_notreelog, "notreelog"},
- {Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
+ enum {
+ Opt_fatal_errors_panic,
+ Opt_fatal_errors_bug,
+ };
- /* Rescue options */
- {Opt_rescue, "rescue=%s"},
+ static const struct constant_table btrfs_parameter_fatal_errors[] = {
+ { "panic", Opt_fatal_errors_panic },
+ { "bug", Opt_fatal_errors_bug },
+ {}
+ };
+
+ enum {
+ Opt_discard_sync,
+ Opt_discard_async,
+ };
+
+ static const struct constant_table btrfs_parameter_discard[] = {
+ { "sync", Opt_discard_sync },
+ { "async", Opt_discard_async },
+ {}
+ };
+
+ enum {
+ Opt_space_cache_v1,
+ Opt_space_cache_v2,
+ };
+
+ static const struct constant_table btrfs_parameter_space_cache[] = {
+ { "v1", Opt_space_cache_v1 },
+ { "v2", Opt_space_cache_v2 },
+ {}
+ };
+
+ enum {
+ Opt_rescue_usebackuproot,
+ Opt_rescue_nologreplay,
+ Opt_rescue_ignorebadroots,
+ Opt_rescue_ignoredatacsums,
+ Opt_rescue_parameter_all,
+ };
+
+ static const struct constant_table btrfs_parameter_rescue[] = {
+ { "usebackuproot", Opt_rescue_usebackuproot },
+ { "nologreplay", Opt_rescue_nologreplay },
+ { "ignorebadroots", Opt_rescue_ignorebadroots },
+ { "ibadroots", Opt_rescue_ignorebadroots },
+ { "ignoredatacsums", Opt_rescue_ignoredatacsums },
+ { "idatacsums", Opt_rescue_ignoredatacsums },
+ { "all", Opt_rescue_parameter_all },
+ {}
+ };
+
+ #ifdef CONFIG_BTRFS_DEBUG
+ enum {
+ Opt_fragment_parameter_data,
+ Opt_fragment_parameter_metadata,
+ Opt_fragment_parameter_all,
+ };
+
+ static const struct constant_table btrfs_parameter_fragment[] = {
+ { "data", Opt_fragment_parameter_data },
+ { "metadata", Opt_fragment_parameter_metadata },
+ { "all", Opt_fragment_parameter_all },
+ {}
+ };
+ #endif
+
+ static const struct fs_parameter_spec btrfs_fs_parameters[] = {
+ fsparam_flag_no("acl", Opt_acl),
+ fsparam_flag_no("autodefrag", Opt_defrag),
+ fsparam_flag_no("barrier", Opt_barrier),
+ fsparam_flag("clear_cache", Opt_clear_cache),
+ fsparam_u32("commit", Opt_commit_interval),
+ fsparam_flag("compress", Opt_compress),
+ fsparam_string("compress", Opt_compress_type),
+ fsparam_flag("compress-force", Opt_compress_force),
+ fsparam_string("compress-force", Opt_compress_force_type),
+ fsparam_flag_no("datacow", Opt_datacow),
+ fsparam_flag_no("datasum", Opt_datasum),
+ fsparam_flag("degraded", Opt_degraded),
+ fsparam_string("device", Opt_device),
+ fsparam_flag_no("discard", Opt_discard),
+ fsparam_enum("discard", Opt_discard_mode, btrfs_parameter_discard),
+ fsparam_enum("fatal_errors", Opt_fatal_errors, btrfs_parameter_fatal_errors),
+ fsparam_flag_no("flushoncommit", Opt_flushoncommit),
+ fsparam_string("max_inline", Opt_max_inline),
+ fsparam_u32("metadata_ratio", Opt_ratio),
+ fsparam_flag("rescan_uuid_tree", Opt_rescan_uuid_tree),
+ fsparam_flag("skip_balance", Opt_skip_balance),
+ fsparam_flag_no("space_cache", Opt_space_cache),
+ fsparam_enum("space_cache", Opt_space_cache_version, btrfs_parameter_space_cache),
+ fsparam_flag_no("ssd", Opt_ssd),
+ fsparam_flag_no("ssd_spread", Opt_ssd_spread),
+ fsparam_string("subvol", Opt_subvol),
+ fsparam_flag("subvol=", Opt_subvol_empty),
+ fsparam_u64("subvolid", Opt_subvolid),
+ fsparam_u32("thread_pool", Opt_thread_pool),
+ fsparam_flag_no("treelog", Opt_treelog),
+ fsparam_flag("user_subvol_rm_allowed", Opt_user_subvol_rm_allowed),
+
+ /* Rescue options. */
+ fsparam_enum("rescue", Opt_rescue, btrfs_parameter_rescue),
/* Deprecated, with alias rescue=nologreplay */
- {Opt_nologreplay, "nologreplay"},
+ __fsparam(NULL, "nologreplay", Opt_nologreplay, fs_param_deprecated, NULL),
/* Deprecated, with alias rescue=usebackuproot */
- {Opt_usebackuproot, "usebackuproot"},
+ __fsparam(NULL, "usebackuproot", Opt_usebackuproot, fs_param_deprecated, NULL),
- /* Deprecated options */
- {Opt_recovery, "recovery"},
-
- /* Debugging options */
- {Opt_enospc_debug, "enospc_debug"},
- {Opt_noenospc_debug, "noenospc_debug"},
+ /* Debugging options. */
+ fsparam_flag_no("enospc_debug", Opt_enospc_debug),
#ifdef CONFIG_BTRFS_DEBUG
- {Opt_fragment_data, "fragment=data"},
- {Opt_fragment_metadata, "fragment=metadata"},
- {Opt_fragment_all, "fragment=all"},
+ fsparam_enum("fragment", Opt_fragment, btrfs_parameter_fragment),
#endif
#ifdef CONFIG_BTRFS_FS_REF_VERIFY
- {Opt_ref_verify, "ref_verify"},
+ fsparam_flag("ref_verify", Opt_ref_verify),
#endif
- {Opt_err, NULL},
+ {}
};
- static const match_table_t rescue_tokens = {
- {Opt_usebackuproot, "usebackuproot"},
- {Opt_nologreplay, "nologreplay"},
- {Opt_ignorebadroots, "ignorebadroots"},
- {Opt_ignorebadroots, "ibadroots"},
- {Opt_ignoredatacsums, "ignoredatacsums"},
- {Opt_ignoredatacsums, "idatacsums"},
- {Opt_rescue_all, "all"},
- {Opt_err, NULL},
- };
-
- static bool check_ro_option(struct btrfs_fs_info *fs_info, unsigned long opt,
- const char *opt_name)
++/* No support for restricting writes to btrfs devices yet... */
++static inline blk_mode_t btrfs_open_mode(struct fs_context *fc)
+{
- if (fs_info->mount_opt & opt) {
- btrfs_err(fs_info, "%s must be used with ro mount option",
- opt_name);
- return true;
- }
- return false;
++ return sb_open_mode(fc->sb_flags) & ~BLK_OPEN_RESTRICT_WRITES;
+}
+
- static int parse_rescue_options(struct btrfs_fs_info *info, const char *options)
+ static int btrfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
{
- char *opts;
- char *orig;
- char *p;
- substring_t args[MAX_OPT_ARGS];
- int ret = 0;
+ struct btrfs_fs_context *ctx = fc->fs_private;
+ struct fs_parse_result result;
+ int opt;
- opts = kstrdup(options, GFP_KERNEL);
- if (!opts)
- return -ENOMEM;
- orig = opts;
+ opt = fs_parse(fc, btrfs_fs_parameters, param, &result);
+ if (opt < 0)
+ return opt;
- while ((p = strsep(&opts, ":")) != NULL) {
- int token;
+ switch (opt) {
+ case Opt_degraded:
+ btrfs_set_opt(ctx->mount_opt, DEGRADED);
+ break;
+ case Opt_subvol_empty:
+ /*
+ * This exists because we used to allow it on accident, so we're
+ * keeping it to maintain ABI. See 37becec95ac3 ("Btrfs: allow
+ * empty subvol= again").
+ */
+ break;
+ case Opt_subvol:
+ kfree(ctx->subvol_name);
+ ctx->subvol_name = kstrdup(param->string, GFP_KERNEL);
+ if (!ctx->subvol_name)
+ return -ENOMEM;
+ break;
+ case Opt_subvolid:
+ ctx->subvol_objectid = result.uint_64;
- if (!*p)
- continue;
- token = match_token(p, rescue_tokens, args);
- switch (token){
- case Opt_usebackuproot:
- btrfs_info(info,
- "trying to use backup root at mount time");
- btrfs_set_opt(info->mount_opt, USEBACKUPROOT);
- break;
- case Opt_nologreplay:
- btrfs_set_and_info(info, NOLOGREPLAY,
- "disabling log replay at mount time");
- break;
- case Opt_ignorebadroots:
- btrfs_set_and_info(info, IGNOREBADROOTS,
- "ignoring bad roots");
- break;
- case Opt_ignoredatacsums:
- btrfs_set_and_info(info, IGNOREDATACSUMS,
- "ignoring data csums");
- break;
- case Opt_rescue_all:
- btrfs_info(info, "enabling all of the rescue options");
- btrfs_set_and_info(info, IGNOREDATACSUMS,
- "ignoring data csums");
- btrfs_set_and_info(info, IGNOREBADROOTS,
- "ignoring bad roots");
- btrfs_set_and_info(info, NOLOGREPLAY,
- "disabling log replay at mount time");
- break;
- case Opt_err:
- btrfs_info(info, "unrecognized rescue option '%s'", p);
- ret = -EINVAL;
- goto out;
- default:
- break;
- }
+ /* subvolid=0 means give me the original fs_tree. */
+ if (!ctx->subvol_objectid)
+ ctx->subvol_objectid = BTRFS_FS_TREE_OBJECTID;
+ break;
+ case Opt_device: {
+ struct btrfs_device *device;
- blk_mode_t mode = sb_open_mode(fc->sb_flags);
++ blk_mode_t mode = btrfs_open_mode(fc);
+ mutex_lock(&uuid_mutex);
+ device = btrfs_scan_one_device(param->string, mode, false);
+ mutex_unlock(&uuid_mutex);
+ if (IS_ERR(device))
+ return PTR_ERR(device);
+ break;
}
- out:
- kfree(orig);
- return ret;
- }
-
- /*
- * Regular mount options parser. Everything that is needed only when
- * reading in a new superblock is parsed here.
- * XXX JDM: This needs to be cleaned up for remount.
- */
- int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
- unsigned long new_flags)
- {
- substring_t args[MAX_OPT_ARGS];
- char *p, *num;
- int intarg;
- int ret = 0;
- char *compress_type;
- bool compress_force = false;
- enum btrfs_compression_type saved_compress_type;
- int saved_compress_level;
- bool saved_compress_force;
- int no_compress = 0;
- const bool remounting = test_bit(BTRFS_FS_STATE_REMOUNTING, &info->fs_state);
-
- if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE))
- btrfs_set_opt(info->mount_opt, FREE_SPACE_TREE);
- else if (btrfs_free_space_cache_v1_active(info)) {
- if (btrfs_is_zoned(info)) {
- btrfs_info(info,
- "zoned: clearing existing space cache");
- btrfs_set_super_cache_generation(info->super_copy, 0);
+ case Opt_datasum:
+ if (result.negated) {
+ btrfs_set_opt(ctx->mount_opt, NODATASUM);
} else {
- btrfs_set_opt(info->mount_opt, SPACE_CACHE);
+ btrfs_clear_opt(ctx->mount_opt, NODATACOW);
+ btrfs_clear_opt(ctx->mount_opt, NODATASUM);
}
- }
-
- /*
- * Even the options are empty, we still need to do extra check
- * against new flags
- */
- if (!options)
- goto check;
-
- while ((p = strsep(&options, ",")) != NULL) {
- int token;
- if (!*p)
- continue;
-
- token = match_token(p, tokens, args);
- switch (token) {
- case Opt_degraded:
- btrfs_info(info, "allowing degraded mounts");
- btrfs_set_opt(info->mount_opt, DEGRADED);
- break;
- case Opt_subvol:
- case Opt_subvol_empty:
- case Opt_subvolid:
- case Opt_device:
- /*
- * These are parsed by btrfs_parse_subvol_options or
- * btrfs_parse_device_options and can be ignored here.
- */
- break;
- case Opt_nodatasum:
- btrfs_set_and_info(info, NODATASUM,
- "setting nodatasum");
- break;
- case Opt_datasum:
- if (btrfs_test_opt(info, NODATASUM)) {
- if (btrfs_test_opt(info, NODATACOW))
- btrfs_info(info,
- "setting datasum, datacow enabled");
- else
- btrfs_info(info, "setting datasum");
- }
- btrfs_clear_opt(info->mount_opt, NODATACOW);
- btrfs_clear_opt(info->mount_opt, NODATASUM);
- break;
- case Opt_nodatacow:
- if (!btrfs_test_opt(info, NODATACOW)) {
- if (!btrfs_test_opt(info, COMPRESS) ||
- !btrfs_test_opt(info, FORCE_COMPRESS)) {
- btrfs_info(info,
- "setting nodatacow, compression disabled");
- } else {
- btrfs_info(info, "setting nodatacow");
- }
- }
- btrfs_clear_opt(info->mount_opt, COMPRESS);
- btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
- btrfs_set_opt(info->mount_opt, NODATACOW);
- btrfs_set_opt(info->mount_opt, NODATASUM);
- break;
- case Opt_datacow:
- btrfs_clear_and_info(info, NODATACOW,
- "setting datacow");
- break;
- case Opt_compress_force:
- case Opt_compress_force_type:
- compress_force = true;
- fallthrough;
- case Opt_compress:
- case Opt_compress_type:
- saved_compress_type = btrfs_test_opt(info,
- COMPRESS) ?
- info->compress_type : BTRFS_COMPRESS_NONE;
- saved_compress_force =
- btrfs_test_opt(info, FORCE_COMPRESS);
- saved_compress_level = info->compress_level;
- if (token == Opt_compress ||
- token == Opt_compress_force ||
- strncmp(args[0].from, "zlib", 4) == 0) {
- compress_type = "zlib";
-
- info->compress_type = BTRFS_COMPRESS_ZLIB;
- info->compress_level = BTRFS_ZLIB_DEFAULT_LEVEL;
- /*
- * args[0] contains uninitialized data since
- * for these tokens we don't expect any
- * parameter.
- */
- if (token != Opt_compress &&
- token != Opt_compress_force)
- info->compress_level =
- btrfs_compress_str2level(
- BTRFS_COMPRESS_ZLIB,
- args[0].from + 4);
- btrfs_set_opt(info->mount_opt, COMPRESS);
- btrfs_clear_opt(info->mount_opt, NODATACOW);
- btrfs_clear_opt(info->mount_opt, NODATASUM);
- no_compress = 0;
- } else if (strncmp(args[0].from, "lzo", 3) == 0) {
- compress_type = "lzo";
- info->compress_type = BTRFS_COMPRESS_LZO;
- info->compress_level = 0;
- btrfs_set_opt(info->mount_opt, COMPRESS);
- btrfs_clear_opt(info->mount_opt, NODATACOW);
- btrfs_clear_opt(info->mount_opt, NODATASUM);
- btrfs_set_fs_incompat(info, COMPRESS_LZO);
- no_compress = 0;
- } else if (strncmp(args[0].from, "zstd", 4) == 0) {
- compress_type = "zstd";
- info->compress_type = BTRFS_COMPRESS_ZSTD;
- info->compress_level =
- btrfs_compress_str2level(
- BTRFS_COMPRESS_ZSTD,
- args[0].from + 4);
- btrfs_set_opt(info->mount_opt, COMPRESS);
- btrfs_clear_opt(info->mount_opt, NODATACOW);
- btrfs_clear_opt(info->mount_opt, NODATASUM);
- btrfs_set_fs_incompat(info, COMPRESS_ZSTD);
- no_compress = 0;
- } else if (strncmp(args[0].from, "no", 2) == 0) {
- compress_type = "no";
- info->compress_level = 0;
- info->compress_type = 0;
- btrfs_clear_opt(info->mount_opt, COMPRESS);
- btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
- compress_force = false;
- no_compress++;
- } else {
- btrfs_err(info, "unrecognized compression value %s",
- args[0].from);
- ret = -EINVAL;
- goto out;
- }
-
- if (compress_force) {
- btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
- } else {
- /*
- * If we remount from compress-force=xxx to
- * compress=xxx, we need clear FORCE_COMPRESS
- * flag, otherwise, there is no way for users
- * to disable forcible compression separately.
- */
- btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
- }
- if (no_compress == 1) {
- btrfs_info(info, "use no compression");
- } else if ((info->compress_type != saved_compress_type) ||
- (compress_force != saved_compress_force) ||
- (info->compress_level != saved_compress_level)) {
- btrfs_info(info, "%s %s compression, level %d",
- (compress_force) ? "force" : "use",
- compress_type, info->compress_level);
- }
- compress_force = false;
- break;
- case Opt_ssd:
- btrfs_set_and_info(info, SSD,
- "enabling ssd optimizations");
- btrfs_clear_opt(info->mount_opt, NOSSD);
- break;
- case Opt_ssd_spread:
- btrfs_set_and_info(info, SSD,
- "enabling ssd optimizations");
- btrfs_set_and_info(info, SSD_SPREAD,
- "using spread ssd allocation scheme");
- btrfs_clear_opt(info->mount_opt, NOSSD);
- break;
- case Opt_nossd:
- btrfs_set_opt(info->mount_opt, NOSSD);
- btrfs_clear_and_info(info, SSD,
- "not using ssd optimizations");
- fallthrough;
- case Opt_nossd_spread:
- btrfs_clear_and_info(info, SSD_SPREAD,
- "not using spread ssd allocation scheme");
- break;
- case Opt_barrier:
- btrfs_clear_and_info(info, NOBARRIER,
- "turning on barriers");
- break;
- case Opt_nobarrier:
- btrfs_set_and_info(info, NOBARRIER,
- "turning off barriers");
- break;
- case Opt_thread_pool:
- ret = match_int(&args[0], &intarg);
- if (ret) {
- btrfs_err(info, "unrecognized thread_pool value %s",
- args[0].from);
- goto out;
- } else if (intarg == 0) {
- btrfs_err(info, "invalid value 0 for thread_pool");
- ret = -EINVAL;
- goto out;
- }
- info->thread_pool_size = intarg;
- break;
- case Opt_max_inline:
- num = match_strdup(&args[0]);
- if (num) {
- info->max_inline = memparse(num, NULL);
- kfree(num);
-
- if (info->max_inline) {
- info->max_inline = min_t(u64,
- info->max_inline,
- info->sectorsize);
- }
- btrfs_info(info, "max_inline at %llu",
- info->max_inline);
- } else {
- ret = -ENOMEM;
- goto out;
- }
- break;
- case Opt_acl:
+ break;
+ case Opt_datacow:
+ if (result.negated) {
+ btrfs_clear_opt(ctx->mount_opt, COMPRESS);
+ btrfs_clear_opt(ctx->mount_opt, FORCE_COMPRESS);
+ btrfs_set_opt(ctx->mount_opt, NODATACOW);
+ btrfs_set_opt(ctx->mount_opt, NODATASUM);
+ } else {
+ btrfs_clear_opt(ctx->mount_opt, NODATACOW);
+ }
+ break;
+ case Opt_compress_force:
+ case Opt_compress_force_type:
+ btrfs_set_opt(ctx->mount_opt, FORCE_COMPRESS);
+ fallthrough;
+ case Opt_compress:
+ case Opt_compress_type:
+ if (opt == Opt_compress || opt == Opt_compress_force) {
+ ctx->compress_type = BTRFS_COMPRESS_ZLIB;
+ ctx->compress_level = BTRFS_ZLIB_DEFAULT_LEVEL;
+ btrfs_set_opt(ctx->mount_opt, COMPRESS);
+ btrfs_clear_opt(ctx->mount_opt, NODATACOW);
+ btrfs_clear_opt(ctx->mount_opt, NODATASUM);
+ } else if (strncmp(param->string, "zlib", 4) == 0) {
+ ctx->compress_type = BTRFS_COMPRESS_ZLIB;
+ ctx->compress_level =
+ btrfs_compress_str2level(BTRFS_COMPRESS_ZLIB,
+ param->string + 4);
+ btrfs_set_opt(ctx->mount_opt, COMPRESS);
+ btrfs_clear_opt(ctx->mount_opt, NODATACOW);
+ btrfs_clear_opt(ctx->mount_opt, NODATASUM);
+ } else if (strncmp(param->string, "lzo", 3) == 0) {
+ ctx->compress_type = BTRFS_COMPRESS_LZO;
+ ctx->compress_level = 0;
+ btrfs_set_opt(ctx->mount_opt, COMPRESS);
+ btrfs_clear_opt(ctx->mount_opt, NODATACOW);
+ btrfs_clear_opt(ctx->mount_opt, NODATASUM);
+ } else if (strncmp(param->string, "zstd", 4) == 0) {
+ ctx->compress_type = BTRFS_COMPRESS_ZSTD;
+ ctx->compress_level =
+ btrfs_compress_str2level(BTRFS_COMPRESS_ZSTD,
+ param->string + 4);
+ btrfs_set_opt(ctx->mount_opt, COMPRESS);
+ btrfs_clear_opt(ctx->mount_opt, NODATACOW);
+ btrfs_clear_opt(ctx->mount_opt, NODATASUM);
+ } else if (strncmp(param->string, "no", 2) == 0) {
+ ctx->compress_level = 0;
+ ctx->compress_type = 0;
+ btrfs_clear_opt(ctx->mount_opt, COMPRESS);
+ btrfs_clear_opt(ctx->mount_opt, FORCE_COMPRESS);
+ } else {
+ btrfs_err(NULL, "unrecognized compression value %s",
+ param->string);
+ return -EINVAL;
+ }
+ break;
+ case Opt_ssd:
+ if (result.negated) {
+ btrfs_set_opt(ctx->mount_opt, NOSSD);
+ btrfs_clear_opt(ctx->mount_opt, SSD);
+ btrfs_clear_opt(ctx->mount_opt, SSD_SPREAD);
+ } else {
+ btrfs_set_opt(ctx->mount_opt, SSD);
+ btrfs_clear_opt(ctx->mount_opt, NOSSD);
+ }
+ break;
+ case Opt_ssd_spread:
+ if (result.negated) {
+ btrfs_clear_opt(ctx->mount_opt, SSD_SPREAD);
+ } else {
+ btrfs_set_opt(ctx->mount_opt, SSD);
+ btrfs_set_opt(ctx->mount_opt, SSD_SPREAD);
+ btrfs_clear_opt(ctx->mount_opt, NOSSD);
+ }
+ break;
+ case Opt_barrier:
+ if (result.negated)
+ btrfs_set_opt(ctx->mount_opt, NOBARRIER);
+ else
+ btrfs_clear_opt(ctx->mount_opt, NOBARRIER);
+ break;
+ case Opt_thread_pool:
+ if (result.uint_32 == 0) {
+ btrfs_err(NULL, "invalid value 0 for thread_pool");
+ return -EINVAL;
+ }
+ ctx->thread_pool_size = result.uint_32;
+ break;
+ case Opt_max_inline:
+ ctx->max_inline = memparse(param->string, NULL);
+ break;
+ case Opt_acl:
+ if (result.negated) {
+ fc->sb_flags &= ~SB_POSIXACL;
+ } else {
#ifdef CONFIG_BTRFS_FS_POSIX_ACL
- info->sb->s_flags |= SB_POSIXACL;
- break;
+ fc->sb_flags |= SB_POSIXACL;
#else
- btrfs_err(info, "support for ACL not compiled in!");
- ret = -EINVAL;
- goto out;
+ btrfs_err(NULL, "support for ACL not compiled in");
+ return -EINVAL;
#endif
- case Opt_noacl:
- info->sb->s_flags &= ~SB_POSIXACL;
- break;
- case Opt_notreelog:
- btrfs_set_and_info(info, NOTREELOG,
- "disabling tree log");
- break;
- case Opt_treelog:
- btrfs_clear_and_info(info, NOTREELOG,
- "enabling tree log");
- break;
- case Opt_norecovery:
- case Opt_nologreplay:
- btrfs_warn(info,
+ }
+ /*
+ * VFS limits the ability to toggle ACL on and off via remount,
+ * despite every file system allowing this. This seems to be
+ * an oversight since we all do, but it'll fail if we're
+ * remounting. So don't set the mask here, we'll check it in
+ * btrfs_reconfigure and do the toggling ourselves.
+ */
+ if (fc->purpose != FS_CONTEXT_FOR_RECONFIGURE)
+ fc->sb_flags_mask |= SB_POSIXACL;
+ break;
+ case Opt_treelog:
+ if (result.negated)
+ btrfs_set_opt(ctx->mount_opt, NOTREELOG);
+ else
+ btrfs_clear_opt(ctx->mount_opt, NOTREELOG);
+ break;
+ case Opt_nologreplay:
+ btrfs_warn(NULL,
"'nologreplay' is deprecated, use 'rescue=nologreplay' instead");
- btrfs_set_and_info(info, NOLOGREPLAY,
- "disabling log replay at mount time");
- break;
- case Opt_flushoncommit:
- btrfs_set_and_info(info, FLUSHONCOMMIT,
- "turning on flush-on-commit");
- break;
- case Opt_noflushoncommit:
- btrfs_clear_and_info(info, FLUSHONCOMMIT,
- "turning off flush-on-commit");
- break;
- case Opt_ratio:
- ret = match_int(&args[0], &intarg);
- if (ret) {
- btrfs_err(info, "unrecognized metadata_ratio value %s",
- args[0].from);
- goto out;
- }
- info->metadata_ratio = intarg;
- btrfs_info(info, "metadata ratio %u",
- info->metadata_ratio);
- break;
- case Opt_discard:
- case Opt_discard_mode:
- if (token == Opt_discard ||
- strcmp(args[0].from, "sync") == 0) {
- btrfs_clear_opt(info->mount_opt, DISCARD_ASYNC);
- btrfs_set_and_info(info, DISCARD_SYNC,
- "turning on sync discard");
- } else if (strcmp(args[0].from, "async") == 0) {
- btrfs_clear_opt(info->mount_opt, DISCARD_SYNC);
- btrfs_set_and_info(info, DISCARD_ASYNC,
- "turning on async discard");
- } else {
- btrfs_err(info, "unrecognized discard mode value %s",
- args[0].from);
- ret = -EINVAL;
- goto out;
- }
- btrfs_clear_opt(info->mount_opt, NODISCARD);
- break;
- case Opt_nodiscard:
- btrfs_clear_and_info(info, DISCARD_SYNC,
- "turning off discard");
- btrfs_clear_and_info(info, DISCARD_ASYNC,
- "turning off async discard");
- btrfs_set_opt(info->mount_opt, NODISCARD);
- break;
- case Opt_space_cache:
- case Opt_space_cache_version:
- /*
- * We already set FREE_SPACE_TREE above because we have
- * compat_ro(FREE_SPACE_TREE) set, and we aren't going
- * to allow v1 to be set for extent tree v2, simply
- * ignore this setting if we're extent tree v2.
- */
- if (btrfs_fs_incompat(info, EXTENT_TREE_V2))
- break;
- if (token == Opt_space_cache ||
- strcmp(args[0].from, "v1") == 0) {
- btrfs_clear_opt(info->mount_opt,
- FREE_SPACE_TREE);
- btrfs_set_and_info(info, SPACE_CACHE,
- "enabling disk space caching");
- } else if (strcmp(args[0].from, "v2") == 0) {
- btrfs_clear_opt(info->mount_opt,
- SPACE_CACHE);
- btrfs_set_and_info(info, FREE_SPACE_TREE,
- "enabling free space tree");
- } else {
- btrfs_err(info, "unrecognized space_cache value %s",
- args[0].from);
- ret = -EINVAL;
- goto out;
- }
- break;
- case Opt_rescan_uuid_tree:
- btrfs_set_opt(info->mount_opt, RESCAN_UUID_TREE);
- break;
- case Opt_no_space_cache:
- /*
- * We cannot operate without the free space tree with
- * extent tree v2, ignore this option.
- */
- if (btrfs_fs_incompat(info, EXTENT_TREE_V2))
- break;
- if (btrfs_test_opt(info, SPACE_CACHE)) {
- btrfs_clear_and_info(info, SPACE_CACHE,
- "disabling disk space caching");
- }
- if (btrfs_test_opt(info, FREE_SPACE_TREE)) {
- btrfs_clear_and_info(info, FREE_SPACE_TREE,
- "disabling free space tree");
- }
- break;
- case Opt_inode_cache:
- case Opt_noinode_cache:
- btrfs_warn(info,
- "the 'inode_cache' option is deprecated and has no effect since 5.11");
- break;
- case Opt_clear_cache:
- /*
- * We cannot clear the free space tree with extent tree
- * v2, ignore this option.
- */
- if (btrfs_fs_incompat(info, EXTENT_TREE_V2))
- break;
- btrfs_set_and_info(info, CLEAR_CACHE,
- "force clearing of disk cache");
+ btrfs_set_opt(ctx->mount_opt, NOLOGREPLAY);
+ break;
+ case Opt_flushoncommit:
+ if (result.negated)
+ btrfs_clear_opt(ctx->mount_opt, FLUSHONCOMMIT);
+ else
+ btrfs_set_opt(ctx->mount_opt, FLUSHONCOMMIT);
+ break;
+ case Opt_ratio:
+ ctx->metadata_ratio = result.uint_32;
+ break;
+ case Opt_discard:
+ if (result.negated) {
+ btrfs_clear_opt(ctx->mount_opt, DISCARD_SYNC);
+ btrfs_clear_opt(ctx->mount_opt, DISCARD_ASYNC);
+ btrfs_set_opt(ctx->mount_opt, NODISCARD);
+ } else {
+ btrfs_set_opt(ctx->mount_opt, DISCARD_SYNC);
+ btrfs_clear_opt(ctx->mount_opt, DISCARD_ASYNC);
+ }
+ break;
+ case Opt_discard_mode:
+ switch (result.uint_32) {
+ case Opt_discard_sync:
+ btrfs_clear_opt(ctx->mount_opt, DISCARD_ASYNC);
+ btrfs_set_opt(ctx->mount_opt, DISCARD_SYNC);
break;
- case Opt_user_subvol_rm_allowed:
- btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
+ case Opt_discard_async:
+ btrfs_clear_opt(ctx->mount_opt, DISCARD_SYNC);
+ btrfs_set_opt(ctx->mount_opt, DISCARD_ASYNC);
break;
- case Opt_enospc_debug:
- btrfs_set_opt(info->mount_opt, ENOSPC_DEBUG);
+ default:
+ btrfs_err(NULL, "unrecognized discard mode value %s",
+ param->key);
+ return -EINVAL;
+ }
+ btrfs_clear_opt(ctx->mount_opt, NODISCARD);
+ break;
+ case Opt_space_cache:
+ if (result.negated) {
+ btrfs_set_opt(ctx->mount_opt, NOSPACECACHE);
+ btrfs_clear_opt(ctx->mount_opt, SPACE_CACHE);
+ btrfs_clear_opt(ctx->mount_opt, FREE_SPACE_TREE);
+ } else {
+ btrfs_clear_opt(ctx->mount_opt, FREE_SPACE_TREE);
+ btrfs_set_opt(ctx->mount_opt, SPACE_CACHE);
+ }
+ break;
+ case Opt_space_cache_version:
+ switch (result.uint_32) {
+ case Opt_space_cache_v1:
+ btrfs_set_opt(ctx->mount_opt, SPACE_CACHE);
+ btrfs_clear_opt(ctx->mount_opt, FREE_SPACE_TREE);
break;
- case Opt_noenospc_debug:
- btrfs_clear_opt(info->mount_opt, ENOSPC_DEBUG);
+ case Opt_space_cache_v2:
+ btrfs_clear_opt(ctx->mount_opt, SPACE_CACHE);
+ btrfs_set_opt(ctx->mount_opt, FREE_SPACE_TREE);
break;
- case Opt_defrag:
- btrfs_set_and_info(info, AUTO_DEFRAG,
- "enabling auto defrag");
+ default:
+ btrfs_err(NULL, "unrecognized space_cache value %s",
+ param->key);
+ return -EINVAL;
+ }
+ break;
+ case Opt_rescan_uuid_tree:
+ btrfs_set_opt(ctx->mount_opt, RESCAN_UUID_TREE);
+ break;
+ case Opt_clear_cache:
+ btrfs_set_opt(ctx->mount_opt, CLEAR_CACHE);
+ break;
+ case Opt_user_subvol_rm_allowed:
+ btrfs_set_opt(ctx->mount_opt, USER_SUBVOL_RM_ALLOWED);
+ break;
+ case Opt_enospc_debug:
+ if (result.negated)
+ btrfs_clear_opt(ctx->mount_opt, ENOSPC_DEBUG);
+ else
+ btrfs_set_opt(ctx->mount_opt, ENOSPC_DEBUG);
+ break;
+ case Opt_defrag:
+ if (result.negated)
+ btrfs_clear_opt(ctx->mount_opt, AUTO_DEFRAG);
+ else
+ btrfs_set_opt(ctx->mount_opt, AUTO_DEFRAG);
+ break;
+ case Opt_usebackuproot:
+ btrfs_warn(NULL,
+ "'usebackuproot' is deprecated, use 'rescue=usebackuproot' instead");
+ btrfs_set_opt(ctx->mount_opt, USEBACKUPROOT);
+
+ /* If we're loading the backup roots we can't trust the space cache. */
+ btrfs_set_opt(ctx->mount_opt, CLEAR_CACHE);
+ break;
+ case Opt_skip_balance:
+ btrfs_set_opt(ctx->mount_opt, SKIP_BALANCE);
+ break;
+ case Opt_fatal_errors:
+ switch (result.uint_32) {
+ case Opt_fatal_errors_panic:
+ btrfs_set_opt(ctx->mount_opt, PANIC_ON_FATAL_ERROR);
break;
- case Opt_nodefrag:
- btrfs_clear_and_info(info, AUTO_DEFRAG,
- "disabling auto defrag");
+ case Opt_fatal_errors_bug:
+ btrfs_clear_opt(ctx->mount_opt, PANIC_ON_FATAL_ERROR);
break;
- case Opt_recovery:
- case Opt_usebackuproot:
- btrfs_warn(info,
- "'%s' is deprecated, use 'rescue=usebackuproot' instead",
- token == Opt_recovery ? "recovery" :
- "usebackuproot");
- btrfs_info(info,
- "trying to use backup root at mount time");
- btrfs_set_opt(info->mount_opt, USEBACKUPROOT);
+ default:
+ btrfs_err(NULL, "unrecognized fatal_errors value %s",
+ param->key);
+ return -EINVAL;
+ }
+ break;
+ case Opt_commit_interval:
+ ctx->commit_interval = result.uint_32;
+ if (ctx->commit_interval == 0)
+ ctx->commit_interval = BTRFS_DEFAULT_COMMIT_INTERVAL;
+ break;
+ case Opt_rescue:
+ switch (result.uint_32) {
+ case Opt_rescue_usebackuproot:
+ btrfs_set_opt(ctx->mount_opt, USEBACKUPROOT);
break;
- case Opt_skip_balance:
- btrfs_set_opt(info->mount_opt, SKIP_BALANCE);
+ case Opt_rescue_nologreplay:
+ btrfs_set_opt(ctx->mount_opt, NOLOGREPLAY);
break;
- case Opt_fatal_errors:
- if (strcmp(args[0].from, "panic") == 0) {
- btrfs_set_opt(info->mount_opt,
- PANIC_ON_FATAL_ERROR);
- } else if (strcmp(args[0].from, "bug") == 0) {
- btrfs_clear_opt(info->mount_opt,
- PANIC_ON_FATAL_ERROR);
- } else {
- btrfs_err(info, "unrecognized fatal_errors value %s",
- args[0].from);
- ret = -EINVAL;
- goto out;
- }
+ case Opt_rescue_ignorebadroots:
+ btrfs_set_opt(ctx->mount_opt, IGNOREBADROOTS);
break;
- case Opt_commit_interval:
- intarg = 0;
- ret = match_int(&args[0], &intarg);
- if (ret) {
- btrfs_err(info, "unrecognized commit_interval value %s",
- args[0].from);
- ret = -EINVAL;
- goto out;
- }
- if (intarg == 0) {
- btrfs_info(info,
- "using default commit interval %us",
- BTRFS_DEFAULT_COMMIT_INTERVAL);
- intarg = BTRFS_DEFAULT_COMMIT_INTERVAL;
- } else if (intarg > 300) {
- btrfs_warn(info, "excessive commit interval %d",
- intarg);
- }
- info->commit_interval = intarg;
+ case Opt_rescue_ignoredatacsums:
+ btrfs_set_opt(ctx->mount_opt, IGNOREDATACSUMS);
break;
- case Opt_rescue:
- ret = parse_rescue_options(info, args[0].from);
- if (ret < 0) {
- btrfs_err(info, "unrecognized rescue value %s",
- args[0].from);
- goto out;
- }
+ case Opt_rescue_parameter_all:
+ btrfs_set_opt(ctx->mount_opt, IGNOREDATACSUMS);
+ btrfs_set_opt(ctx->mount_opt, IGNOREBADROOTS);
+ btrfs_set_opt(ctx->mount_opt, NOLOGREPLAY);
break;
+ default:
+ btrfs_info(NULL, "unrecognized rescue option '%s'",
+ param->key);
+ return -EINVAL;
+ }
+ break;
#ifdef CONFIG_BTRFS_DEBUG
- case Opt_fragment_all:
- btrfs_info(info, "fragmenting all space");
- btrfs_set_opt(info->mount_opt, FRAGMENT_DATA);
- btrfs_set_opt(info->mount_opt, FRAGMENT_METADATA);
+ case Opt_fragment:
+ switch (result.uint_32) {
+ case Opt_fragment_parameter_all:
+ btrfs_set_opt(ctx->mount_opt, FRAGMENT_DATA);
+ btrfs_set_opt(ctx->mount_opt, FRAGMENT_METADATA);
break;
- case Opt_fragment_metadata:
- btrfs_info(info, "fragmenting metadata");
- btrfs_set_opt(info->mount_opt,
- FRAGMENT_METADATA);
+ case Opt_fragment_parameter_metadata:
+ btrfs_set_opt(ctx->mount_opt, FRAGMENT_METADATA);
break;
- case Opt_fragment_data:
- btrfs_info(info, "fragmenting data");
- btrfs_set_opt(info->mount_opt, FRAGMENT_DATA);
+ case Opt_fragment_parameter_data:
+ btrfs_set_opt(ctx->mount_opt, FRAGMENT_DATA);
break;
+ default:
+ btrfs_info(NULL, "unrecognized fragment option '%s'",
+ param->key);
+ return -EINVAL;
+ }
+ break;
#endif
#ifdef CONFIG_BTRFS_FS_REF_VERIFY
- case Opt_ref_verify:
- btrfs_info(info, "doing ref verification");
- btrfs_set_opt(info->mount_opt, REF_VERIFY);
- break;
+ case Opt_ref_verify:
+ btrfs_set_opt(ctx->mount_opt, REF_VERIFY);
+ break;
#endif
- case Opt_err:
- btrfs_err(info, "unrecognized mount option '%s'", p);
- ret = -EINVAL;
- goto out;
- default:
- break;
- }
+ default:
+ btrfs_err(NULL, "unrecognized mount option '%s'", param->key);
+ return -EINVAL;
}
- check:
- /* We're read-only, don't have to check. */
- if (new_flags & SB_RDONLY)
- goto out;
- if (check_ro_option(info, BTRFS_MOUNT_NOLOGREPLAY, "nologreplay") ||
- check_ro_option(info, BTRFS_MOUNT_IGNOREBADROOTS, "ignorebadroots") ||
- check_ro_option(info, BTRFS_MOUNT_IGNOREDATACSUMS, "ignoredatacsums"))
- ret = -EINVAL;
- out:
- if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE) &&
- !btrfs_test_opt(info, FREE_SPACE_TREE) &&
- !btrfs_test_opt(info, CLEAR_CACHE)) {
- btrfs_err(info, "cannot disable free space tree");
- ret = -EINVAL;
- }
- if (btrfs_fs_compat_ro(info, BLOCK_GROUP_TREE) &&
- !btrfs_test_opt(info, FREE_SPACE_TREE)) {
- btrfs_err(info, "cannot disable free space tree with block-group-tree feature");
- ret = -EINVAL;
- }
- if (!ret)
- ret = btrfs_check_mountopts_zoned(info);
- if (!ret && !remounting) {
- if (btrfs_test_opt(info, SPACE_CACHE))
- btrfs_info(info, "disk space caching is enabled");
- if (btrfs_test_opt(info, FREE_SPACE_TREE))
- btrfs_info(info, "using free space tree");
- }
- return ret;
+ return 0;
}
/*
return 0;
}
- blk_mode_t mode = sb_open_mode(fc->sb_flags);
+ static int btrfs_fc_test_super(struct super_block *sb, struct fs_context *fc)
+ {
+ struct btrfs_fs_info *p = fc->s_fs_info;
+ struct btrfs_fs_info *fs_info = btrfs_sb(sb);
+
+ return fs_info->fs_devices == p->fs_devices;
+ }
+
+ static int btrfs_get_tree_super(struct fs_context *fc)
+ {
+ struct btrfs_fs_info *fs_info = fc->s_fs_info;
+ struct btrfs_fs_context *ctx = fc->fs_private;
+ struct btrfs_fs_devices *fs_devices = NULL;
+ struct block_device *bdev;
+ struct btrfs_device *device;
+ struct super_block *sb;
++ blk_mode_t mode = btrfs_open_mode(fc);
+ int ret;
+
+ btrfs_ctx_to_info(fs_info, ctx);
+ mutex_lock(&uuid_mutex);
+
+ /*
+ * With 'true' passed to btrfs_scan_one_device() (mount time) we expect
+ * either a valid device or an error.
+ */
+ device = btrfs_scan_one_device(fc->source, mode, true);
+ ASSERT(device != NULL);
+ if (IS_ERR(device)) {
+ mutex_unlock(&uuid_mutex);
+ return PTR_ERR(device);
+ }
+
+ fs_devices = device->fs_devices;
+ fs_info->fs_devices = fs_devices;
+
+ ret = btrfs_open_devices(fs_devices, mode, &btrfs_fs_type);
+ mutex_unlock(&uuid_mutex);
+ if (ret)
+ return ret;
+
+ if (!(fc->sb_flags & SB_RDONLY) && fs_devices->rw_devices == 0) {
+ ret = -EACCES;
+ goto error;
+ }
+
+ bdev = fs_devices->latest_dev->bdev;
+
+ /*
+ * From now on the error handling is not straightforward.
+ *
+ * If successful, this will transfer the fs_info into the super block,
+ * and fc->s_fs_info will be NULL. However if there's an existing
+ * super, we'll still have fc->s_fs_info populated. If we error
+ * completely out it'll be cleaned up when we drop the fs_context,
+ * otherwise it's tied to the lifetime of the super_block.
+ */
+ sb = sget_fc(fc, btrfs_fc_test_super, set_anon_super_fc);
+ if (IS_ERR(sb)) {
+ ret = PTR_ERR(sb);
+ goto error;
+ }
+
+ set_device_specific_options(fs_info);
+
+ if (sb->s_root) {
+ btrfs_close_devices(fs_devices);
+ if ((fc->sb_flags ^ sb->s_flags) & SB_RDONLY)
+ ret = -EBUSY;
+ } else {
+ snprintf(sb->s_id, sizeof(sb->s_id), "%pg", bdev);
+ shrinker_debugfs_rename(sb->s_shrink, "sb-btrfs:%s", sb->s_id);
+ btrfs_sb(sb)->bdev_holder = &btrfs_fs_type;
+ ret = btrfs_fill_super(sb, fs_devices, NULL);
+ }
+
+ if (ret) {
+ deactivate_locked_super(sb);
+ return ret;
+ }
+
+ btrfs_clear_oneshot_options(fs_info);
+
+ fc->root = dget(sb->s_root);
+ return 0;
+
+ error:
+ btrfs_close_devices(fs_devices);
+ return ret;
+ }
+
+ /*
+ * Ever since commit 0723a0473fb4 ("btrfs: allow mounting btrfs subvolumes
+ * with different ro/rw options") the following works:
+ *
+ * (i) mount /dev/sda3 -o subvol=foo,ro /mnt/foo
+ * (ii) mount /dev/sda3 -o subvol=bar,rw /mnt/bar
+ *
+ * which looks nice and innocent but is actually pretty intricate and deserves
+ * a long comment.
+ *
+ * On another filesystem a subvolume mount is close to something like:
+ *
+ * (iii) # create rw superblock + initial mount
+ * mount -t xfs /dev/sdb /opt/
+ *
+ * # create ro bind mount
+ * mount --bind -o ro /opt/foo /mnt/foo
+ *
+ * # unmount initial mount
+ * umount /opt
+ *
+ * Of course, there's some special subvolume sauce and there's the fact that the
+ * sb->s_root dentry is really swapped after mount_subtree(). But conceptually
+ * it's very close and will help us understand the issue.
+ *
+ * The old mount API didn't cleanly distinguish between a mount being made ro
+ * and a superblock being made ro. The only way to change the ro state of
+ * either object was by passing ms_rdonly. If a new mount was created via
+ * mount(2) such as:
+ *
+ * mount("/dev/sdb", "/mnt", "xfs", ms_rdonly, null);
+ *
+ * the MS_RDONLY flag being specified had two effects:
+ *
+ * (1) MNT_READONLY was raised -> the resulting mount got
+ * @mnt->mnt_flags |= MNT_READONLY raised.
+ *
+ * (2) MS_RDONLY was passed to the filesystem's mount method and the filesystems
+ * made the superblock ro. Note, how SB_RDONLY has the same value as
+ * ms_rdonly and is raised whenever MS_RDONLY is passed through mount(2).
+ *
+ * Creating a subtree mount via (iii) ends up leaving a rw superblock with a
+ * subtree mounted ro.
+ *
+ * But consider the effect on the old mount API on btrfs subvolume mounting
+ * which combines the distinct step in (iii) into a single step.
+ *
+ * By issuing (i) both the mount and the superblock are turned ro. Now when (ii)
+ * is issued the superblock is ro and thus even if the mount created for (ii) is
+ * rw it wouldn't help. Hence, btrfs needed to transition the superblock from ro
+ * to rw for (ii) which it did using an internal remount call.
+ *
+ * IOW, subvolume mounting was inherently complicated due to the ambiguity of
+ * MS_RDONLY in mount(2). Note, this ambiguity has mount(8) always translate
+ * "ro" to MS_RDONLY. IOW, in both (i) and (ii) "ro" becomes MS_RDONLY when
+ * passed by mount(8) to mount(2).
+ *
+ * Enter the new mount API. The new mount API disambiguates making a mount ro
+ * and making a superblock ro.
+ *
+ * (3) To turn a mount ro the MOUNT_ATTR_ONLY flag can be used with either
+ * fsmount() or mount_setattr() this is a pure VFS level change for a
+ * specific mount or mount tree that is never seen by the filesystem itself.
+ *
+ * (4) To turn a superblock ro the "ro" flag must be used with
+ * fsconfig(FSCONFIG_SET_FLAG, "ro"). This option is seen by the filesystem
+ * in fc->sb_flags.
+ *
+ * This disambiguation has rather positive consequences. Mounting a subvolume
+ * ro will not also turn the superblock ro. Only the mount for the subvolume
+ * will become ro.
+ *
+ * So, if the superblock creation request comes from the new mount API the
+ * caller must have explicitly done:
+ *
+ * fsconfig(FSCONFIG_SET_FLAG, "ro")
+ * fsmount/mount_setattr(MOUNT_ATTR_RDONLY)
+ *
+ * IOW, at some point the caller must have explicitly turned the whole
+ * superblock ro and we shouldn't just undo it like we did for the old mount
+ * API. In any case, it lets us avoid the hack in the new mount API.
+ *
+ * Consequently, the remounting hack must only be used for requests originating
+ * from the old mount API and should be marked for full deprecation so it can be
+ * turned off in a couple of years.
+ *
+ * The new mount API has no reason to support this hack.
+ */
+ static struct vfsmount *btrfs_reconfigure_for_mount(struct fs_context *fc)
+ {
+ struct vfsmount *mnt;
+ int ret;
+ const bool ro2rw = !(fc->sb_flags & SB_RDONLY);
+
+ /*
+ * We got an EBUSY because our SB_RDONLY flag didn't match the existing
+ * super block, so invert our setting here and retry the mount so we
+ * can get our vfsmount.
+ */
+ if (ro2rw)
+ fc->sb_flags |= SB_RDONLY;
+ else
+ fc->sb_flags &= ~SB_RDONLY;
+
+ mnt = fc_mount(fc);
+ if (IS_ERR(mnt))
+ return mnt;
+
+ if (!fc->oldapi || !ro2rw)
+ return mnt;
+
+ /* We need to convert to rw, call reconfigure. */
+ fc->sb_flags &= ~SB_RDONLY;
+ down_write(&mnt->mnt_sb->s_umount);
+ ret = btrfs_reconfigure(fc);
+ up_write(&mnt->mnt_sb->s_umount);
+ if (ret) {
+ mntput(mnt);
+ return ERR_PTR(ret);
+ }
+ return mnt;
+ }
+
+ static int btrfs_get_tree_subvol(struct fs_context *fc)
+ {
+ struct btrfs_fs_info *fs_info = NULL;
+ struct btrfs_fs_context *ctx = fc->fs_private;
+ struct fs_context *dup_fc;
+ struct dentry *dentry;
+ struct vfsmount *mnt;
+
+ /*
+ * Setup a dummy root and fs_info for test/set super. This is because
+ * we don't actually fill this stuff out until open_ctree, but we need
+ * then open_ctree will properly initialize the file system specific
+ * settings later. btrfs_init_fs_info initializes the static elements
+ * of the fs_info (locks and such) to make cleanup easier if we find a
+ * superblock with our given fs_devices later on at sget() time.
+ */
+ fs_info = kvzalloc(sizeof(struct btrfs_fs_info), GFP_KERNEL);
+ if (!fs_info)
+ return -ENOMEM;
+
+ fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_KERNEL);
+ fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_KERNEL);
+ if (!fs_info->super_copy || !fs_info->super_for_commit) {
+ btrfs_free_fs_info(fs_info);
+ return -ENOMEM;
+ }
+ btrfs_init_fs_info(fs_info);
+
+ dup_fc = vfs_dup_fs_context(fc);
+ if (IS_ERR(dup_fc)) {
+ btrfs_free_fs_info(fs_info);
+ return PTR_ERR(dup_fc);
+ }
+
+ /*
+ * When we do the sget_fc this gets transferred to the sb, so we only
+ * need to set it on the dup_fc as this is what creates the super block.
+ */
+ dup_fc->s_fs_info = fs_info;
+
+ /*
+ * We'll do the security settings in our btrfs_get_tree_super() mount
+ * loop, they were duplicated into dup_fc, we can drop the originals
+ * here.
+ */
+ security_free_mnt_opts(&fc->security);
+ fc->security = NULL;
+
+ mnt = fc_mount(dup_fc);
+ if (PTR_ERR_OR_ZERO(mnt) == -EBUSY)
+ mnt = btrfs_reconfigure_for_mount(dup_fc);
+ put_fs_context(dup_fc);
+ if (IS_ERR(mnt))
+ return PTR_ERR(mnt);
+
+ /*
+ * This free's ->subvol_name, because if it isn't set we have to
+ * allocate a buffer to hold the subvol_name, so we just drop our
+ * reference to it here.
+ */
+ dentry = mount_subvol(ctx->subvol_name, ctx->subvol_objectid, mnt);
+ ctx->subvol_name = NULL;
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+
+ fc->root = dentry;
+ return 0;
+ }
+
+ static int btrfs_get_tree(struct fs_context *fc)
+ {
+ /*
+ * Since we use mount_subtree to mount the default/specified subvol, we
+ * have to do mounts in two steps.
+ *
+ * First pass through we call btrfs_get_tree_subvol(), this is just a
+ * wrapper around fc_mount() to call back into here again, and this time
+ * we'll call btrfs_get_tree_super(). This will do the open_ctree() and
+ * everything to open the devices and file system. Then we return back
+ * with a fully constructed vfsmount in btrfs_get_tree_subvol(), and
+ * from there we can do our mount_subvol() call, which will lookup
+ * whichever subvol we're mounting and setup this fc with the
+ * appropriate dentry for the subvol.
+ */
+ if (fc->s_fs_info)
+ return btrfs_get_tree_super(fc);
+ return btrfs_get_tree_subvol(fc);
+ }
+
static void btrfs_kill_super(struct super_block *sb)
{
struct btrfs_fs_info *fs_info = btrfs_sb(sb);
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