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jbd2: precompute number of transaction descriptor blocks

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Instead of computing the number of descriptor blocks a transaction can
have each time we need it (which is currently when starting each
transaction but will become more frequent later) precompute the number
once during journal initialization together with maximum transaction
size. We perform the precomputation whenever journal feature set is
updated similarly as for computation of
journal->j_revoke_records_per_block.

CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20240624170127.3253-2-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Jan Kara
2024-06-24 19:01:18 +02:00
committed by Theodore Ts'o
parent 4aa99c71e4
commit e3a00a2378
3 changed files with 54 additions and 38 deletions
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24
fs/jbd2/transaction.c
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@@ -62,28 +62,6 @@ void jbd2_journal_free_transaction(transaction_t *transaction)
kmem_cache_free(transaction_cache, transaction);
}
/*
* Base amount of descriptor blocks we reserve for each transaction.
*/
static int jbd2_descriptor_blocks_per_trans(journal_t *journal)
{
int tag_space = journal->j_blocksize - sizeof(journal_header_t);
int tags_per_block;
/* Subtract UUID */
tag_space -= 16;
if (jbd2_journal_has_csum_v2or3(journal))
tag_space -= sizeof(struct jbd2_journal_block_tail);
/* Commit code leaves a slack space of 16 bytes at the end of block */
tags_per_block = (tag_space - 16) / journal_tag_bytes(journal);
/*
* Revoke descriptors are accounted separately so we need to reserve
* space for commit block and normal transaction descriptor blocks.
*/
return 1 + DIV_ROUND_UP(journal->j_max_transaction_buffers,
tags_per_block);
}
/*
* jbd2_get_transaction: obtain a new transaction_t object.
*
@@ -109,7 +87,7 @@ static void jbd2_get_transaction(journal_t *journal,
transaction->t_expires = jiffies + journal->j_commit_interval;
atomic_set(&transaction->t_updates, 0);
atomic_set(&transaction->t_outstanding_credits,
jbd2_descriptor_blocks_per_trans(journal) +
journal->j_transaction_overhead_buffers +
atomic_read(&journal->j_reserved_credits));
atomic_set(&transaction->t_outstanding_revokes, 0);
atomic_set(&transaction->t_handle_count, 0);