From abf38abec201cded6094801766d69e11a6c112b6 Mon Sep 17 00:00:00 2001 From: Neeraj Singh Date: Thu, 10 Mar 2022 22:43:20 +0000 Subject: core.fsyncmethod: add writeout-only mode This commit introduces the `core.fsyncMethod` configuration knob, which can currently be set to `fsync` or `writeout-only`. The new writeout-only mode attempts to tell the operating system to flush its in-memory page cache to the storage hardware without issuing a CACHE_FLUSH command to the storage controller. Writeout-only fsync is significantly faster than a vanilla fsync on common hardware, since data is written to a disk-side cache rather than all the way to a durable medium. Later changes in this patch series will take advantage of this primitive to implement batching of hardware flushes. When git_fsync is called with FSYNC_WRITEOUT_ONLY, it may fail and the caller is expected to do an ordinary fsync as needed. On Apple platforms, the fsync system call does not issue a CACHE_FLUSH directive to the storage controller. This change updates fsync to do fcntl(F_FULLFSYNC) to make fsync actually durable. We maintain parity with existing behavior on Apple platforms by setting the default value of the new core.fsyncMethod option. Signed-off-by: Neeraj Singh Signed-off-by: Junio C Hamano --- cache.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'cache.h') diff --git a/cache.h b/cache.h index 04d4d2db25..82f0194a3d 100644 --- a/cache.h +++ b/cache.h @@ -995,6 +995,13 @@ extern char *git_replace_ref_base; extern int fsync_object_files; extern int use_fsync; + +enum fsync_method { + FSYNC_METHOD_FSYNC, + FSYNC_METHOD_WRITEOUT_ONLY +}; + +extern enum fsync_method fsync_method; extern int core_preload_index; extern int precomposed_unicode; extern int protect_hfs; -- cgit v1.2.3 From 020406eaa52e67440d9b78087ec2ce25532cb219 Mon Sep 17 00:00:00 2001 From: Neeraj Singh Date: Thu, 10 Mar 2022 22:43:21 +0000 Subject: core.fsync: introduce granular fsync control infrastructure This commit introduces the infrastructure for the core.fsync configuration knob. The repository components we want to sync are identified by flags so that we can turn on or off syncing for specific components. If core.fsyncObjectFiles is set and the core.fsync configuration also includes FSYNC_COMPONENT_LOOSE_OBJECT, we will fsync any loose objects. This picks the strictest data integrity behavior if core.fsync and core.fsyncObjectFiles are set to conflicting values. This change introduces the currently unused fsync_component helper, which will be used by a later patch that adds fsyncing to the refs backend. Actual configuration and documentation of the fsync components list are in other patches in the series to separate review of the underlying mechanism from the policy of how it's configured. Helped-by: Patrick Steinhardt Signed-off-by: Neeraj Singh Signed-off-by: Junio C Hamano --- builtin/fast-import.c | 2 +- builtin/index-pack.c | 4 ++-- builtin/pack-objects.c | 24 +++++++++++++++++------- bulk-checkin.c | 5 +++-- cache.h | 23 +++++++++++++++++++++++ commit-graph.c | 3 ++- csum-file.c | 5 +++-- csum-file.h | 3 ++- environment.c | 1 + midx.c | 3 ++- object-file.c | 13 +++++++++---- pack-bitmap-write.c | 3 ++- pack-write.c | 13 +++++++------ read-cache.c | 2 +- write-or-die.c | 26 ++++++++++++++++++++++---- 15 files changed, 97 insertions(+), 33 deletions(-) (limited to 'cache.h') diff --git a/builtin/fast-import.c b/builtin/fast-import.c index b7105fcad9..f2c036a895 100644 --- a/builtin/fast-import.c +++ b/builtin/fast-import.c @@ -865,7 +865,7 @@ static void end_packfile(void) struct tag *t; close_pack_windows(pack_data); - finalize_hashfile(pack_file, cur_pack_oid.hash, 0); + finalize_hashfile(pack_file, cur_pack_oid.hash, FSYNC_COMPONENT_PACK, 0); fixup_pack_header_footer(pack_data->pack_fd, pack_data->hash, pack_data->pack_name, object_count, cur_pack_oid.hash, pack_size); diff --git a/builtin/index-pack.c b/builtin/index-pack.c index c45273de3b..c5f12f14df 100644 --- a/builtin/index-pack.c +++ b/builtin/index-pack.c @@ -1290,7 +1290,7 @@ static void conclude_pack(int fix_thin_pack, const char *curr_pack, unsigned cha nr_objects - nr_objects_initial); stop_progress_msg(&progress, msg.buf); strbuf_release(&msg); - finalize_hashfile(f, tail_hash, 0); + finalize_hashfile(f, tail_hash, FSYNC_COMPONENT_PACK, 0); hashcpy(read_hash, pack_hash); fixup_pack_header_footer(output_fd, pack_hash, curr_pack, nr_objects, @@ -1512,7 +1512,7 @@ static void final(const char *final_pack_name, const char *curr_pack_name, if (!from_stdin) { close(input_fd); } else { - fsync_or_die(output_fd, curr_pack_name); + fsync_component_or_die(FSYNC_COMPONENT_PACK, output_fd, curr_pack_name); err = close(output_fd); if (err) die_errno(_("error while closing pack file")); diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c index 178e611f09..c14fee8e99 100644 --- a/builtin/pack-objects.c +++ b/builtin/pack-objects.c @@ -1199,16 +1199,26 @@ static void write_pack_file(void) display_progress(progress_state, written); } - /* - * Did we write the wrong # entries in the header? - * If so, rewrite it like in fast-import - */ if (pack_to_stdout) { - finalize_hashfile(f, hash, CSUM_HASH_IN_STREAM | CSUM_CLOSE); + /* + * We never fsync when writing to stdout since we may + * not be writing to an actual pack file. For instance, + * the upload-pack code passes a pipe here. Calling + * fsync on a pipe results in unnecessary + * synchronization with the reader on some platforms. + */ + finalize_hashfile(f, hash, FSYNC_COMPONENT_NONE, + CSUM_HASH_IN_STREAM | CSUM_CLOSE); } else if (nr_written == nr_remaining) { - finalize_hashfile(f, hash, CSUM_HASH_IN_STREAM | CSUM_FSYNC | CSUM_CLOSE); + finalize_hashfile(f, hash, FSYNC_COMPONENT_PACK, + CSUM_HASH_IN_STREAM | CSUM_FSYNC | CSUM_CLOSE); } else { - int fd = finalize_hashfile(f, hash, 0); + /* + * If we wrote the wrong number of entries in the + * header, rewrite it like in fast-import. + */ + + int fd = finalize_hashfile(f, hash, FSYNC_COMPONENT_PACK, 0); fixup_pack_header_footer(fd, hash, pack_tmp_name, nr_written, hash, offset); close(fd); diff --git a/bulk-checkin.c b/bulk-checkin.c index 8785b2ac80..a2cf9dcbc8 100644 --- a/bulk-checkin.c +++ b/bulk-checkin.c @@ -53,9 +53,10 @@ static void finish_bulk_checkin(struct bulk_checkin_state *state) unlink(state->pack_tmp_name); goto clear_exit; } else if (state->nr_written == 1) { - finalize_hashfile(state->f, hash, CSUM_HASH_IN_STREAM | CSUM_FSYNC | CSUM_CLOSE); + finalize_hashfile(state->f, hash, FSYNC_COMPONENT_PACK, + CSUM_HASH_IN_STREAM | CSUM_FSYNC | CSUM_CLOSE); } else { - int fd = finalize_hashfile(state->f, hash, 0); + int fd = finalize_hashfile(state->f, hash, FSYNC_COMPONENT_PACK, 0); fixup_pack_header_footer(fd, hash, state->pack_tmp_name, state->nr_written, hash, state->offset); diff --git a/cache.h b/cache.h index 82f0194a3d..7ac1959258 100644 --- a/cache.h +++ b/cache.h @@ -993,6 +993,27 @@ void reset_shared_repository(void); extern int read_replace_refs; extern char *git_replace_ref_base; +/* + * These values are used to help identify parts of a repository to fsync. + * FSYNC_COMPONENT_NONE identifies data that will not be a persistent part of the + * repository and so shouldn't be fsynced. + */ +enum fsync_component { + FSYNC_COMPONENT_NONE, + FSYNC_COMPONENT_LOOSE_OBJECT = 1 << 0, + FSYNC_COMPONENT_PACK = 1 << 1, + FSYNC_COMPONENT_PACK_METADATA = 1 << 2, + FSYNC_COMPONENT_COMMIT_GRAPH = 1 << 3, +}; + +#define FSYNC_COMPONENTS_DEFAULT (FSYNC_COMPONENT_PACK | \ + FSYNC_COMPONENT_PACK_METADATA | \ + FSYNC_COMPONENT_COMMIT_GRAPH) + +/* + * A bitmask indicating which components of the repo should be fsynced. + */ +extern enum fsync_component fsync_components; extern int fsync_object_files; extern int use_fsync; @@ -1707,6 +1728,8 @@ int copy_file_with_time(const char *dst, const char *src, int mode); void write_or_die(int fd, const void *buf, size_t count); void fsync_or_die(int fd, const char *); +int fsync_component(enum fsync_component component, int fd); +void fsync_component_or_die(enum fsync_component component, int fd, const char *msg); ssize_t read_in_full(int fd, void *buf, size_t count); ssize_t write_in_full(int fd, const void *buf, size_t count); diff --git a/commit-graph.c b/commit-graph.c index 265c010122..64897f57d9 100644 --- a/commit-graph.c +++ b/commit-graph.c @@ -1942,7 +1942,8 @@ static int write_commit_graph_file(struct write_commit_graph_context *ctx) } close_commit_graph(ctx->r->objects); - finalize_hashfile(f, file_hash, CSUM_HASH_IN_STREAM | CSUM_FSYNC); + finalize_hashfile(f, file_hash, FSYNC_COMPONENT_COMMIT_GRAPH, + CSUM_HASH_IN_STREAM | CSUM_FSYNC); free_chunkfile(cf); if (ctx->split) { diff --git a/csum-file.c b/csum-file.c index 26e8a6df44..59ef3398ca 100644 --- a/csum-file.c +++ b/csum-file.c @@ -58,7 +58,8 @@ static void free_hashfile(struct hashfile *f) free(f); } -int finalize_hashfile(struct hashfile *f, unsigned char *result, unsigned int flags) +int finalize_hashfile(struct hashfile *f, unsigned char *result, + enum fsync_component component, unsigned int flags) { int fd; @@ -69,7 +70,7 @@ int finalize_hashfile(struct hashfile *f, unsigned char *result, unsigned int fl if (flags & CSUM_HASH_IN_STREAM) flush(f, f->buffer, the_hash_algo->rawsz); if (flags & CSUM_FSYNC) - fsync_or_die(f->fd, f->name); + fsync_component_or_die(component, f->fd, f->name); if (flags & CSUM_CLOSE) { if (close(f->fd)) die_errno("%s: sha1 file error on close", f->name); diff --git a/csum-file.h b/csum-file.h index 291215b34e..0d29f528fb 100644 --- a/csum-file.h +++ b/csum-file.h @@ -1,6 +1,7 @@ #ifndef CSUM_FILE_H #define CSUM_FILE_H +#include "cache.h" #include "hash.h" struct progress; @@ -38,7 +39,7 @@ int hashfile_truncate(struct hashfile *, struct hashfile_checkpoint *); struct hashfile *hashfd(int fd, const char *name); struct hashfile *hashfd_check(const char *name); struct hashfile *hashfd_throughput(int fd, const char *name, struct progress *tp); -int finalize_hashfile(struct hashfile *, unsigned char *, unsigned int); +int finalize_hashfile(struct hashfile *, unsigned char *, enum fsync_component, unsigned int); void hashwrite(struct hashfile *, const void *, unsigned int); void hashflush(struct hashfile *f); void crc32_begin(struct hashfile *); diff --git a/environment.c b/environment.c index 3e3620d759..36ca5fb2e7 100644 --- a/environment.c +++ b/environment.c @@ -45,6 +45,7 @@ int pack_compression_level = Z_DEFAULT_COMPRESSION; int fsync_object_files; int use_fsync = -1; enum fsync_method fsync_method = FSYNC_METHOD_DEFAULT; +enum fsync_component fsync_components = FSYNC_COMPONENTS_DEFAULT; size_t packed_git_window_size = DEFAULT_PACKED_GIT_WINDOW_SIZE; size_t packed_git_limit = DEFAULT_PACKED_GIT_LIMIT; size_t delta_base_cache_limit = 96 * 1024 * 1024; diff --git a/midx.c b/midx.c index 865170bad0..107365d211 100644 --- a/midx.c +++ b/midx.c @@ -1438,7 +1438,8 @@ static int write_midx_internal(const char *object_dir, write_midx_header(f, get_num_chunks(cf), ctx.nr - dropped_packs); write_chunkfile(cf, &ctx); - finalize_hashfile(f, midx_hash, CSUM_FSYNC | CSUM_HASH_IN_STREAM); + finalize_hashfile(f, midx_hash, FSYNC_COMPONENT_PACK_METADATA, + CSUM_FSYNC | CSUM_HASH_IN_STREAM); free_chunkfile(cf); if (flags & MIDX_WRITE_REV_INDEX && diff --git a/object-file.c b/object-file.c index 03bd6a3baf..e3f0bf27ff 100644 --- a/object-file.c +++ b/object-file.c @@ -1849,11 +1849,16 @@ int hash_object_file(const struct git_hash_algo *algo, const void *buf, /* Finalize a file on disk, and close it. */ static void close_loose_object(int fd) { - if (!the_repository->objects->odb->will_destroy) { - if (fsync_object_files) - fsync_or_die(fd, "loose object file"); - } + if (the_repository->objects->odb->will_destroy) + goto out; + if (fsync_object_files > 0) + fsync_or_die(fd, "loose object file"); + else + fsync_component_or_die(FSYNC_COMPONENT_LOOSE_OBJECT, fd, + "loose object file"); + +out: if (close(fd) != 0) die_errno(_("error when closing loose object file")); } diff --git a/pack-bitmap-write.c b/pack-bitmap-write.c index cab3eaa2ac..cf681547f2 100644 --- a/pack-bitmap-write.c +++ b/pack-bitmap-write.c @@ -719,7 +719,8 @@ void bitmap_writer_finish(struct pack_idx_entry **index, if (options & BITMAP_OPT_HASH_CACHE) write_hash_cache(f, index, index_nr); - finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_FSYNC | CSUM_CLOSE); + finalize_hashfile(f, NULL, FSYNC_COMPONENT_PACK_METADATA, + CSUM_HASH_IN_STREAM | CSUM_FSYNC | CSUM_CLOSE); if (adjust_shared_perm(tmp_file.buf)) die_errno("unable to make temporary bitmap file readable"); diff --git a/pack-write.c b/pack-write.c index a5846f3a34..51812cb129 100644 --- a/pack-write.c +++ b/pack-write.c @@ -159,9 +159,9 @@ const char *write_idx_file(const char *index_name, struct pack_idx_entry **objec } hashwrite(f, sha1, the_hash_algo->rawsz); - finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_CLOSE | - ((opts->flags & WRITE_IDX_VERIFY) - ? 0 : CSUM_FSYNC)); + finalize_hashfile(f, NULL, FSYNC_COMPONENT_PACK_METADATA, + CSUM_HASH_IN_STREAM | CSUM_CLOSE | + ((opts->flags & WRITE_IDX_VERIFY) ? 0 : CSUM_FSYNC)); return index_name; } @@ -281,8 +281,9 @@ const char *write_rev_file_order(const char *rev_name, if (rev_name && adjust_shared_perm(rev_name) < 0) die(_("failed to make %s readable"), rev_name); - finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_CLOSE | - ((flags & WRITE_IDX_VERIFY) ? 0 : CSUM_FSYNC)); + finalize_hashfile(f, NULL, FSYNC_COMPONENT_PACK_METADATA, + CSUM_HASH_IN_STREAM | CSUM_CLOSE | + ((flags & WRITE_IDX_VERIFY) ? 0 : CSUM_FSYNC)); return rev_name; } @@ -390,7 +391,7 @@ void fixup_pack_header_footer(int pack_fd, the_hash_algo->final_fn(partial_pack_hash, &old_hash_ctx); the_hash_algo->final_fn(new_pack_hash, &new_hash_ctx); write_or_die(pack_fd, new_pack_hash, the_hash_algo->rawsz); - fsync_or_die(pack_fd, pack_name); + fsync_component_or_die(FSYNC_COMPONENT_PACK, pack_fd, pack_name); } char *index_pack_lockfile(int ip_out, int *is_well_formed) diff --git a/read-cache.c b/read-cache.c index 79b9b99ebf..df869691fd 100644 --- a/read-cache.c +++ b/read-cache.c @@ -3089,7 +3089,7 @@ static int do_write_index(struct index_state *istate, struct tempfile *tempfile, return -1; } - finalize_hashfile(f, istate->oid.hash, CSUM_HASH_IN_STREAM); + finalize_hashfile(f, istate->oid.hash, FSYNC_COMPONENT_NONE, CSUM_HASH_IN_STREAM); if (close_tempfile_gently(tempfile)) { error(_("could not close '%s'"), get_tempfile_path(tempfile)); return -1; diff --git a/write-or-die.c b/write-or-die.c index 9faa5f9f56..c4fd91b5b4 100644 --- a/write-or-die.c +++ b/write-or-die.c @@ -56,21 +56,39 @@ void fprintf_or_die(FILE *f, const char *fmt, ...) } } -void fsync_or_die(int fd, const char *msg) +static int maybe_fsync(int fd) { if (use_fsync < 0) use_fsync = git_env_bool("GIT_TEST_FSYNC", 1); if (!use_fsync) - return; + return 0; if (fsync_method == FSYNC_METHOD_WRITEOUT_ONLY && git_fsync(fd, FSYNC_WRITEOUT_ONLY) >= 0) - return; + return 0; + + return git_fsync(fd, FSYNC_HARDWARE_FLUSH); +} - if (git_fsync(fd, FSYNC_HARDWARE_FLUSH) < 0) +void fsync_or_die(int fd, const char *msg) +{ + if (maybe_fsync(fd) < 0) die_errno("fsync error on '%s'", msg); } +int fsync_component(enum fsync_component component, int fd) +{ + if (fsync_components & component) + return maybe_fsync(fd); + return 0; +} + +void fsync_component_or_die(enum fsync_component component, int fd, const char *msg) +{ + if (fsync_components & component) + fsync_or_die(fd, msg); +} + void write_or_die(int fd, const void *buf, size_t count) { if (write_in_full(fd, buf, count) < 0) { -- cgit v1.2.3 From ba95e96d4c6eed42e30ac3c8b260f4459e3a8575 Mon Sep 17 00:00:00 2001 From: Neeraj Singh Date: Thu, 10 Mar 2022 22:43:23 +0000 Subject: core.fsync: new option to harden the index This commit introduces the new ability for the user to harden the index. In the event of a system crash, the index must be durable for the user to actually find a file that has been added to the repo and then deleted from the working tree. We use the presence of the COMMIT_LOCK flag and absence of the alternate_index_output as a proxy for determining whether we're updating the persistent index of the repo or some temporary index. We don't sync these temporary indexes. Signed-off-by: Neeraj Singh Signed-off-by: Junio C Hamano --- cache.h | 1 + config.c | 1 + read-cache.c | 19 +++++++++++++------ 3 files changed, 15 insertions(+), 6 deletions(-) (limited to 'cache.h') diff --git a/cache.h b/cache.h index 7ac1959258..e08eeac6c1 100644 --- a/cache.h +++ b/cache.h @@ -1004,6 +1004,7 @@ enum fsync_component { FSYNC_COMPONENT_PACK = 1 << 1, FSYNC_COMPONENT_PACK_METADATA = 1 << 2, FSYNC_COMPONENT_COMMIT_GRAPH = 1 << 3, + FSYNC_COMPONENT_INDEX = 1 << 4, }; #define FSYNC_COMPONENTS_DEFAULT (FSYNC_COMPONENT_PACK | \ diff --git a/config.c b/config.c index 94a4598b5f..80f33c9198 100644 --- a/config.c +++ b/config.c @@ -1331,6 +1331,7 @@ static const struct fsync_component_name { { "pack", FSYNC_COMPONENT_PACK }, { "pack-metadata", FSYNC_COMPONENT_PACK_METADATA }, { "commit-graph", FSYNC_COMPONENT_COMMIT_GRAPH }, + { "index", FSYNC_COMPONENT_INDEX }, }; static enum fsync_component parse_fsync_components(const char *var, const char *string) diff --git a/read-cache.c b/read-cache.c index df869691fd..7683b67925 100644 --- a/read-cache.c +++ b/read-cache.c @@ -2842,7 +2842,7 @@ static int record_ieot(void) * rely on it. */ static int do_write_index(struct index_state *istate, struct tempfile *tempfile, - int strip_extensions) + int strip_extensions, unsigned flags) { uint64_t start = getnanotime(); struct hashfile *f; @@ -2856,6 +2856,7 @@ static int do_write_index(struct index_state *istate, struct tempfile *tempfile, struct strbuf previous_name_buf = STRBUF_INIT, *previous_name; int drop_cache_tree = istate->drop_cache_tree; off_t offset; + int csum_fsync_flag; int ieot_entries = 1; struct index_entry_offset_table *ieot = NULL; int nr, nr_threads; @@ -3089,7 +3090,13 @@ static int do_write_index(struct index_state *istate, struct tempfile *tempfile, return -1; } - finalize_hashfile(f, istate->oid.hash, FSYNC_COMPONENT_NONE, CSUM_HASH_IN_STREAM); + csum_fsync_flag = 0; + if (!alternate_index_output && (flags & COMMIT_LOCK)) + csum_fsync_flag = CSUM_FSYNC; + + finalize_hashfile(f, istate->oid.hash, FSYNC_COMPONENT_INDEX, + CSUM_HASH_IN_STREAM | csum_fsync_flag); + if (close_tempfile_gently(tempfile)) { error(_("could not close '%s'"), get_tempfile_path(tempfile)); return -1; @@ -3144,7 +3151,7 @@ static int do_write_locked_index(struct index_state *istate, struct lock_file *l */ trace2_region_enter_printf("index", "do_write_index", the_repository, "%s", get_lock_file_path(lock)); - ret = do_write_index(istate, lock->tempfile, 0); + ret = do_write_index(istate, lock->tempfile, 0, flags); trace2_region_leave_printf("index", "do_write_index", the_repository, "%s", get_lock_file_path(lock)); @@ -3238,7 +3245,7 @@ static int clean_shared_index_files(const char *current_hex) } static int write_shared_index(struct index_state *istate, - struct tempfile **temp) + struct tempfile **temp, unsigned flags) { struct split_index *si = istate->split_index; int ret, was_full = !istate->sparse_index; @@ -3248,7 +3255,7 @@ static int write_shared_index(struct index_state *istate, trace2_region_enter_printf("index", "shared/do_write_index", the_repository, "%s", get_tempfile_path(*temp)); - ret = do_write_index(si->base, *temp, 1); + ret = do_write_index(si->base, *temp, 1, flags); trace2_region_leave_printf("index", "shared/do_write_index", the_repository, "%s", get_tempfile_path(*temp)); @@ -3357,7 +3364,7 @@ int write_locked_index(struct index_state *istate, struct lock_file *lock, ret = do_write_locked_index(istate, lock, flags); goto out; } - ret = write_shared_index(istate, &temp); + ret = write_shared_index(istate, &temp, flags); saved_errno = errno; if (is_tempfile_active(temp)) -- cgit v1.2.3 From b9f5d0358d2e882d47f496c1a5589f6cebc25578 Mon Sep 17 00:00:00 2001 From: Neeraj Singh Date: Tue, 15 Mar 2022 12:12:45 -0700 Subject: core.fsync: documentation and user-friendly aggregate options This commit adds aggregate options for the core.fsync setting that are more user-friendly. These options are specified in terms of 'levels of safety', indicating which Git operations are considered to be sync points for durability. The new documentation is also included here in its entirety for ease of review. Signed-off-by: Neeraj Singh Signed-off-by: Junio C Hamano --- Documentation/config/core.txt | 40 ++++++++++++++++++++++++++++++++++++++++ cache.h | 23 ++++++++++++++++++++--- config.c | 5 +++++ 3 files changed, 65 insertions(+), 3 deletions(-) (limited to 'cache.h') diff --git a/Documentation/config/core.txt b/Documentation/config/core.txt index ab911d6e26..9a3ad71e9e 100644 --- a/Documentation/config/core.txt +++ b/Documentation/config/core.txt @@ -547,6 +547,46 @@ core.whitespace:: is relevant for `indent-with-non-tab` and when Git fixes `tab-in-indent` errors. The default tab width is 8. Allowed values are 1 to 63. +core.fsync:: + A comma-separated list of components of the repository that + should be hardened via the core.fsyncMethod when created or + modified. You can disable hardening of any component by + prefixing it with a '-'. Items that are not hardened may be + lost in the event of an unclean system shutdown. Unless you + have special requirements, it is recommended that you leave + this option empty or pick one of `committed`, `added`, + or `all`. ++ +When this configuration is encountered, the set of components starts with +the platform default value, disabled components are removed, and additional +components are added. `none` resets the state so that the platform default +is ignored. ++ +The empty string resets the fsync configuration to the platform +default. The default on most platforms is equivalent to +`core.fsync=committed,-loose-object`, which has good performance, +but risks losing recent work in the event of an unclean system shutdown. ++ +* `none` clears the set of fsynced components. +* `loose-object` hardens objects added to the repo in loose-object form. +* `pack` hardens objects added to the repo in packfile form. +* `pack-metadata` hardens packfile bitmaps and indexes. +* `commit-graph` hardens the commit graph file. +* `index` hardens the index when it is modified. +* `objects` is an aggregate option that is equivalent to + `loose-object,pack`. +* `derived-metadata` is an aggregate option that is equivalent to + `pack-metadata,commit-graph`. +* `committed` is an aggregate option that is currently equivalent to + `objects`. This mode sacrifices some performance to ensure that work + that is committed to the repository with `git commit` or similar commands + is hardened. +* `added` is an aggregate option that is currently equivalent to + `committed,index`. This mode sacrifices additional performance to + ensure that the results of commands like `git add` and similar operations + are hardened. +* `all` is an aggregate option that syncs all individual components above. + core.fsyncMethod:: A value indicating the strategy Git will use to harden repository data using fsync and related primitives. diff --git a/cache.h b/cache.h index e08eeac6c1..86680f144e 100644 --- a/cache.h +++ b/cache.h @@ -1007,9 +1007,26 @@ enum fsync_component { FSYNC_COMPONENT_INDEX = 1 << 4, }; -#define FSYNC_COMPONENTS_DEFAULT (FSYNC_COMPONENT_PACK | \ - FSYNC_COMPONENT_PACK_METADATA | \ - FSYNC_COMPONENT_COMMIT_GRAPH) +#define FSYNC_COMPONENTS_OBJECTS (FSYNC_COMPONENT_LOOSE_OBJECT | \ + FSYNC_COMPONENT_PACK) + +#define FSYNC_COMPONENTS_DERIVED_METADATA (FSYNC_COMPONENT_PACK_METADATA | \ + FSYNC_COMPONENT_COMMIT_GRAPH) + +#define FSYNC_COMPONENTS_DEFAULT (FSYNC_COMPONENTS_OBJECTS | \ + FSYNC_COMPONENTS_DERIVED_METADATA | \ + ~FSYNC_COMPONENT_LOOSE_OBJECT) + +#define FSYNC_COMPONENTS_COMMITTED (FSYNC_COMPONENTS_OBJECTS) + +#define FSYNC_COMPONENTS_ADDED (FSYNC_COMPONENTS_COMMITTED | \ + FSYNC_COMPONENT_INDEX) + +#define FSYNC_COMPONENTS_ALL (FSYNC_COMPONENT_LOOSE_OBJECT | \ + FSYNC_COMPONENT_PACK | \ + FSYNC_COMPONENT_PACK_METADATA | \ + FSYNC_COMPONENT_COMMIT_GRAPH | \ + FSYNC_COMPONENT_INDEX) /* * A bitmask indicating which components of the repo should be fsynced. diff --git a/config.c b/config.c index 80f33c9198..fd8e165931 100644 --- a/config.c +++ b/config.c @@ -1332,6 +1332,11 @@ static const struct fsync_component_name { { "pack-metadata", FSYNC_COMPONENT_PACK_METADATA }, { "commit-graph", FSYNC_COMPONENT_COMMIT_GRAPH }, { "index", FSYNC_COMPONENT_INDEX }, + { "objects", FSYNC_COMPONENTS_OBJECTS }, + { "derived-metadata", FSYNC_COMPONENTS_DERIVED_METADATA }, + { "committed", FSYNC_COMPONENTS_COMMITTED }, + { "added", FSYNC_COMPONENTS_ADDED }, + { "all", FSYNC_COMPONENTS_ALL }, }; static enum fsync_component parse_fsync_components(const char *var, const char *string) -- cgit v1.2.3 From e5ec440c982417d39908b9a4bab79523a6a37f6c Mon Sep 17 00:00:00 2001 From: Neeraj Singh Date: Tue, 29 Mar 2022 21:41:52 +0000 Subject: core.fsync: fix incorrect expression for default configuration Commit b9f5d035 (core.fsync: documentation and user-friendly aggregate options, 2022-03-15) introduced an incorrect value for FSYNC_COMPONENTS_DEFAULT. We need an AND-NOT rather than OR-NOT. Signed-off-by: Neeraj Singh Signed-off-by: Junio C Hamano --- cache.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'cache.h') diff --git a/cache.h b/cache.h index 86680f144e..e0b7415972 100644 --- a/cache.h +++ b/cache.h @@ -1013,8 +1013,8 @@ enum fsync_component { #define FSYNC_COMPONENTS_DERIVED_METADATA (FSYNC_COMPONENT_PACK_METADATA | \ FSYNC_COMPONENT_COMMIT_GRAPH) -#define FSYNC_COMPONENTS_DEFAULT (FSYNC_COMPONENTS_OBJECTS | \ - FSYNC_COMPONENTS_DERIVED_METADATA | \ +#define FSYNC_COMPONENTS_DEFAULT ((FSYNC_COMPONENTS_OBJECTS | \ + FSYNC_COMPONENTS_DERIVED_METADATA) & \ ~FSYNC_COMPONENT_LOOSE_OBJECT) #define FSYNC_COMPONENTS_COMMITTED (FSYNC_COMPONENTS_OBJECTS) -- cgit v1.2.3