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Sync no longer requires clearing the past hash

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It no longer assumes past hashes are valid if even a single unsynced
block exists, which indicates a previous sync was interrupted.

While this makes syncing slower after an interruption, it preserves the
past hash in the content file, enabling a more reliable fix if a
disk fails following an incomplete sync.

This ensures the --import option remains functional even after an
interrupted sync.
This commit is contained in:
Andrea Mazzoleni 2026-04-26 15:59:58 +02:00
parent fd13d8e161
commit fe82b48d96
7 changed files with 117 additions and 150 deletions
Download patch file Download diff file Expand all files Collapse all files

65
cmdline/scan.c
View file

@ -271,23 +271,25 @@ static void scan_file_allocate(struct snapraid_scan* scan, struct snapraid_file*
/* otherwise it's a DELETED one */
assert(over_state == BLOCK_STATE_DELETED);
/*
* In this cases we don't know if the old state is still the one
* stored inside the parity, because after an aborted sync, the parity
* may be or may be not have been updated with the data that it's now
* deleted.
*
* We anyway keep the hash as the new sync will not assume it correct,
* but the check/fix may be using it.
*
* For example:
* - One file is deleted
* - Sync aborted after updating the parity to the new state,
* but without saving the content file representing this new state.
* - Another file is added again (exactly here)
* with the hash of DELETED block not representing the real parity state
*/
/* copy the past hash of the block */
memcpy(block->hash, over_block->hash, BLOCK_HASH_SIZE);
/* if we have not already cleared the past hash */
if (!state->clear_past_hash) {
/* in this case we don't know if the old state is still the one */
/* stored inside the parity, because after an aborted sync, the parity */
/* may be or may be not have been updated with the new data */
/* Then we reset the hash to a bogus value */
/* For example: */
/* - One file is deleted */
/* - Sync aborted after, updating the parity to the new state, */
/* but without saving the content file representing this new state. */
/* - Another file is added again (exactly here) */
/* with the hash of DELETED block not representing the real parity state */
hash_invalid_set(block->hash);
}
}
}
@ -314,7 +316,6 @@ static void scan_file_allocate(struct snapraid_scan* scan, struct snapraid_file*
*/
static void scan_file_deallocate(struct snapraid_scan* scan, struct snapraid_file* file)
{
struct snapraid_state* state = scan->state;
struct snapraid_disk* disk = scan->disk;
block_off_t i;
@ -348,21 +349,23 @@ static void scan_file_deallocate(struct snapraid_scan* scan, struct snapraid_fil
/* we keep the hash making it an "old" hash, because the parity is still containing data for it */
break;
case BLOCK_STATE_CHG :
/* if we have not already cleared the past hash */
if (!state->clear_past_hash) {
/* in these cases we don't know if the old state is still the one */
/* stored inside the parity, because after an aborted sync, the parity */
/* may be or may be not have been updated with the data that it's now */
/* deleted. Then we reset the hash to a bogus value. */
/* For example: */
/* - One file is added */
/* - Sync aborted after updating the parity to the new state, */
/* but without saving the content file representing this new state. */
/* - File is now deleted after the aborted sync */
/* - Sync again, deleting the blocks (exactly here) */
/* with the hash of CHG block not representing the real parity state */
hash_invalid_set(block->hash);
}
/*
* In this cases we don't know if the old state is still the one
* stored inside the parity, because after an aborted sync, the parity
* may be or may be not have been updated with the data that it's now
* deleted.
*
* We anyway keep the hash as the new sync will not assume it correct,
* but the check/fix may be using it.
*
* For example:
* - One file is added
* - Sync aborted after updating the parity to the new state,
* but without saving the content file representing this new state.
* - File is now deleted after the aborted sync
* - Sync again, deleting the blocks (exactly here)
* with the hash of CHG block not representing the real parity state
*/
break;
case BLOCK_STATE_REP :
/* we just don't know the old hash, and then we set it to invalid */