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 <neerajsi@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Neeraj Singh committed
Mar 10, 2022 at 22:43 UTC
ba95e96d4c6eed42e30ac3c8b260f4459e3a8575
3 files changed
+15
-6
cache.h
+1
@@ -1004,6 +1004,7 @@ enum fsync_component {
1004
FSYNC_COMPONENT_PACK = 1 << 1,
1005
FSYNC_COMPONENT_PACK_METADATA = 1 << 2,
1006
FSYNC_COMPONENT_COMMIT_GRAPH = 1 << 3,
1007
+ FSYNC_COMPONENT_INDEX = 1 << 4,
1008
};
1009
1010
#define FSYNC_COMPONENTS_DEFAULT (FSYNC_COMPONENT_PACK | \
config.c
+1
@@ -1331,6 +1331,7 @@ static const struct fsync_component_name {
1331
{ "pack", FSYNC_COMPONENT_PACK },
1332
{ "pack-metadata", FSYNC_COMPONENT_PACK_METADATA },
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{ "commit-graph", FSYNC_COMPONENT_COMMIT_GRAPH },
1334
+ { "index", FSYNC_COMPONENT_INDEX },
1335
};
1336
1337
static enum fsync_component parse_fsync_components(const char *var, const char *string)
read-cache.c
+13
-6
@@ -2842,7 +2842,7 @@ static int record_ieot(void)
2842
* rely on it.
2843
*/
2844
static int do_write_index(struct index_state *istate, struct tempfile *tempfile,
2845
- int strip_extensions)
2845
+ int strip_extensions, unsigned flags)
2846
{
2847
uint64_t start = getnanotime();
2848
struct hashfile *f;
@@ -2856,6 +2856,7 @@ static int do_write_index(struct index_state *istate, struct tempfile *tempfile,
2856
struct strbuf previous_name_buf = STRBUF_INIT, *previous_name;
2857
int drop_cache_tree = istate->drop_cache_tree;
2858
off_t offset;
2859
+ int csum_fsync_flag;
2860
int ieot_entries = 1;
2861
struct index_entry_offset_table *ieot = NULL;
2862
int nr, nr_threads;
@@ -3089,7 +3090,13 @@ static int do_write_index(struct index_state *istate, struct tempfile *tempfile,
3090
return -1;
3091
}
3092
3092
- finalize_hashfile(f, istate->oid.hash, FSYNC_COMPONENT_NONE, CSUM_HASH_IN_STREAM);
3093
+ csum_fsync_flag = 0;
3094
+ if (!alternate_index_output && (flags & COMMIT_LOCK))
3095
+ csum_fsync_flag = CSUM_FSYNC;
3096
+
3097
+ finalize_hashfile(f, istate->oid.hash, FSYNC_COMPONENT_INDEX,
3098
+ CSUM_HASH_IN_STREAM | csum_fsync_flag);
3099
+
3100
if (close_tempfile_gently(tempfile)) {
3101
error(_("could not close '%s'"), get_tempfile_path(tempfile));
3102
return -1;
@@ -3144,7 +3151,7 @@ static int do_write_locked_index(struct index_state *istate, struct lock_file *l
3151
*/
3152
trace2_region_enter_printf("index", "do_write_index", the_repository,
3153
"%s", get_lock_file_path(lock));
3147
- ret = do_write_index(istate, lock->tempfile, 0);
3154
+ ret = do_write_index(istate, lock->tempfile, 0, flags);
3155
trace2_region_leave_printf("index", "do_write_index", the_repository,
3156
"%s", get_lock_file_path(lock));
3157
@@ -3238,7 +3245,7 @@ static int clean_shared_index_files(const char *current_hex)
3245
}
3246
3247
static int write_shared_index(struct index_state *istate,
3241
- struct tempfile **temp)
3248
+ struct tempfile **temp, unsigned flags)
3249
{
3250
struct split_index *si = istate->split_index;
3251
int ret, was_full = !istate->sparse_index;
@@ -3248,7 +3255,7 @@ static int write_shared_index(struct index_state *istate,
3255
3256
trace2_region_enter_printf("index", "shared/do_write_index",
3257
the_repository, "%s", get_tempfile_path(*temp));
3251
- ret = do_write_index(si->base, *temp, 1);
3258
+ ret = do_write_index(si->base, *temp, 1, flags);
3259
trace2_region_leave_printf("index", "shared/do_write_index",
3260
the_repository, "%s", get_tempfile_path(*temp));
3261
@@ -3357,7 +3364,7 @@ int write_locked_index(struct index_state *istate, struct lock_file *lock,
3364
ret = do_write_locked_index(istate, lock, flags);
3365
goto out;
3366
}
3360
- ret = write_shared_index(istate, &temp);
3367
+ ret = write_shared_index(istate, &temp, flags);
3368
3369
saved_errno = errno;
3370
if (is_tempfile_active(temp))