On Sun 13-11-11 19:29:31, Yongqiang Yang wrote: > transaction_t is 100 bytes under 32-bit systems. Transactions > allocated from general cache comsume 128 bytes. This patch > lets jbd allocates transacion from special cache. > > Signed-off-by: Yongqiang Yang <xiaoqiangnk@xxxxxxxxx> Space saving isn't probably a good argument here since the number of transactions on the system is going to be rather low (a couple per ext3 filesystem). The reason why I wanted this change for JBD2 is that it makes debugging of memory corruption of a transaction structure much easier (and I've been tracking down issues like this several times already). That being said, I don't find strong need to have this in ext3 and thus I'll take the change in jbd/ext3 if Ted takes the similar change to jbd2/ext4 to keep compatibility. Manish Katiyar was working on it (http://comments.gmane.org/gmane.comp.file-systems.ext4/25884) but it seems it wasn't merged yet. Honza > --- > fs/jbd/checkpoint.c | 2 +- > fs/jbd/journal.c | 3 +++ > fs/jbd/transaction.c | 31 +++++++++++++++++++++++++++++-- > include/linux/jbd.h | 5 +++++ > 4 files changed, 38 insertions(+), 3 deletions(-) > > diff --git a/fs/jbd/checkpoint.c b/fs/jbd/checkpoint.c > index f94fc48..4d98046 100644 > --- a/fs/jbd/checkpoint.c > +++ b/fs/jbd/checkpoint.c > @@ -764,5 +764,5 @@ void __journal_drop_transaction(journal_t *journal, transaction_t *transaction) > > trace_jbd_drop_transaction(journal, transaction); > jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid); > - kfree(transaction); > + journal_free_transaction(transaction); > } > diff --git a/fs/jbd/journal.c b/fs/jbd/journal.c > index 9fe061f..45ca982 100644 > --- a/fs/jbd/journal.c > +++ b/fs/jbd/journal.c > @@ -2004,6 +2004,8 @@ static int __init journal_init_caches(void) > ret = journal_init_journal_head_cache(); > if (ret == 0) > ret = journal_init_handle_cache(); > + if (ret == 0) > + ret = journal_init_transaction_cache(); > return ret; > } > > @@ -2012,6 +2014,7 @@ static void journal_destroy_caches(void) > journal_destroy_revoke_caches(); > journal_destroy_journal_head_cache(); > journal_destroy_handle_cache(); > + journal_destroy_transaction_cache(); > } > > static int __init journal_init(void) > diff --git a/fs/jbd/transaction.c b/fs/jbd/transaction.c > index 7e59c6e..20d76f1 100644 > --- a/fs/jbd/transaction.c > +++ b/fs/jbd/transaction.c > @@ -30,6 +30,32 @@ > > static void __journal_temp_unlink_buffer(struct journal_head *jh); > > +static struct kmem_cache *transaction_cache; > +int __init journal_init_transaction_cache(void) > +{ > + J_ASSERT(!transaction_cache); > + transaction_cache = KMEM_CACHE(transaction_s, > + SLAB_HWCACHE_ALIGN|SLAB_TEMPORARY); > + if (transaction_cache) > + return 0; > + return -ENOMEM; > +} > + > +void __init journal_destroy_transaction_cache(void) > +{ > + if (transaction_cache) { > + kmem_cache_destroy(transaction_cache); > + transaction_cache = NULL; > + } > +} > + > +void journal_free_transaction(transaction_t *transaction) > +{ > + if (unlikely(ZERO_OR_NULL_PTR(transaction))) > + return; > + kmem_cache_free(transaction_cache, transaction); > +} > + > /* > * get_transaction: obtain a new transaction_t object. > * > @@ -100,11 +126,12 @@ static int start_this_handle(journal_t *journal, handle_t *handle) > > alloc_transaction: > if (!journal->j_running_transaction) { > - new_transaction = kzalloc(sizeof(*new_transaction), GFP_NOFS); > + new_transaction = kmem_cache_alloc(transaction_cache, GFP_NOFS); > if (!new_transaction) { > congestion_wait(BLK_RW_ASYNC, HZ/50); > goto alloc_transaction; > } > + memset(new_transaction, 0, sizeof(*new_transaction)); > } > > jbd_debug(3, "New handle %p going live.\n", handle); > @@ -233,7 +260,7 @@ repeat_locked: > lock_map_acquire(&handle->h_lockdep_map); > out: > if (unlikely(new_transaction)) /* It's usually NULL */ > - kfree(new_transaction); > + journal_free_transaction(new_transaction); > return ret; > } > > diff --git a/include/linux/jbd.h b/include/linux/jbd.h > index c7acdde..0f9f0b6 100644 > --- a/include/linux/jbd.h > +++ b/include/linux/jbd.h > @@ -807,6 +807,11 @@ journal_write_metadata_buffer(transaction_t *transaction, > /* Transaction locking */ > extern void __wait_on_journal (journal_t *); > > +/* Transaction cache support */ > +extern void journal_destroy_transaction_cache(void); > +extern int journal_init_transaction_cache(void); > +extern void journal_free_transaction(transaction_t *); > + > /* > * Journal locking. > * > -- > 1.7.5.1 > -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html