Messages in this thread Patch in this message | | | From | Alex Tomas <> | Subject | [PATCH] JBD: log space management optimization | Date | Wed, 19 Jan 2005 18:32:16 +0300 |
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Good day,
during truncate ext3 calls journal_forget() for freed blocks, but before these blocks go to the transaction and jbd reserves space in log for them (->t_outstanding_credits). also, journal_forget() removes these blocks from the transaction, but doesn't correct log space reservation. for example, removal of 500MB file reserves 136 blocks, but only 10 blocks go to the log. a commit is expensive and correct reservation allows us to avoid needless commits. here is the patch. tested on UP.
thanks, Alex
Signed-off-by: Alex Tomas <alex@clusterfs.com>
Index: linux-2.6.7/fs/jbd/transaction.c =================================================================== --- linux-2.6.7.orig/fs/jbd/transaction.c 2004-08-26 17:12:40.000000000 +0400 +++ linux-2.6.7/fs/jbd/transaction.c 2005-01-19 17:23:30.058160408 +0300 @@ -1204,6 +1257,7 @@ transaction_t *transaction = handle->h_transaction; journal_t *journal = transaction->t_journal; struct journal_head *jh; + int drop_reserve = 0; BUFFER_TRACE(bh, "entry"); @@ -1227,6 +1281,7 @@ J_ASSERT_JH(jh, !jh->b_committed_data); __journal_unfile_buffer(jh); + drop_reserve = 1; /* * We are no longer going to journal this buffer. @@ -1249,7 +1304,7 @@ spin_unlock(&journal->j_list_lock); jbd_unlock_bh_state(bh); __bforget(bh); - return; + goto drop; } } } else if (jh->b_transaction) { @@ -1264,6 +1319,7 @@ if (jh->b_next_transaction) { J_ASSERT(jh->b_next_transaction == transaction); jh->b_next_transaction = NULL; + drop_reserve = 1; } } @@ -1271,6 +1327,15 @@ spin_unlock(&journal->j_list_lock); jbd_unlock_bh_state(bh); __brelse(bh); + +drop: + if (drop_reserve) { + /* no need to reserve log space for this block -bzzz */ + spin_lock(&transaction->t_handle_lock); + transaction->t_outstanding_credits--; + spin_unlock(&transaction->t_handle_lock); + } + return; } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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