From e06c8227fd94ec181849ba206bf032be31c4295c Mon Sep 17 00:00:00 2001 From: Joel Becker Date: Thu, 11 Sep 2008 15:35:47 -0700 Subject: jbd2: Add buffer triggers Filesystems often to do compute intensive operation on some metadata. If this operation is repeated many times, it can be very expensive. It would be much nicer if the operation could be performed once before a buffer goes to disk. This adds triggers to jbd2 buffer heads. Just before writing a metadata buffer to the journal, jbd2 will optionally call a commit trigger associated with the buffer. If the journal is aborted, an abort trigger will be called on any dirty buffers as they are dropped from pending transactions. ocfs2 will use this feature. Initially I tried to come up with a more generic trigger that could be used for non-buffer-related events like transaction completion. It doesn't tie nicely, because the information a buffer trigger needs (specific to a journal_head) isn't the same as what a transaction trigger needs (specific to a tranaction_t or perhaps journal_t). So I implemented a buffer set, with the understanding that journal/transaction wide triggers should be implemented separately. There is only one trigger set allowed per buffer. I can't think of any reason to attach more than one set. Contrast this with a journal or transaction in which multiple places may want to watch the entire transaction separately. The trigger sets are considered static allocation from the jbd2 perspective. ocfs2 will just have one trigger set per block type, setting the same set on every bh of the same type. Signed-off-by: Joel Becker Cc: "Theodore Ts'o" Cc: Signed-off-by: Mark Fasheh --- fs/jbd2/commit.c | 9 +++++++++ fs/jbd2/journal.c | 19 +++++++++++++++++++ fs/jbd2/transaction.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 75 insertions(+) (limited to 'fs') diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c index ebc667bc54a..c8a1bace685 100644 --- a/fs/jbd2/commit.c +++ b/fs/jbd2/commit.c @@ -509,6 +509,10 @@ void jbd2_journal_commit_transaction(journal_t *journal) if (is_journal_aborted(journal)) { clear_buffer_jbddirty(jh2bh(jh)); JBUFFER_TRACE(jh, "journal is aborting: refile"); + jbd2_buffer_abort_trigger(jh, + jh->b_frozen_data ? + jh->b_frozen_triggers : + jh->b_triggers); jbd2_journal_refile_buffer(journal, jh); /* If that was the last one, we need to clean up * any descriptor buffers which may have been @@ -844,6 +848,9 @@ restart_loop: * data. * * Otherwise, we can just throw away the frozen data now. + * + * We also know that the frozen data has already fired + * its triggers if they exist, so we can clear that too. */ if (jh->b_committed_data) { jbd2_free(jh->b_committed_data, bh->b_size); @@ -851,10 +858,12 @@ restart_loop: if (jh->b_frozen_data) { jh->b_committed_data = jh->b_frozen_data; jh->b_frozen_data = NULL; + jh->b_frozen_triggers = NULL; } } else if (jh->b_frozen_data) { jbd2_free(jh->b_frozen_data, bh->b_size); jh->b_frozen_data = NULL; + jh->b_frozen_triggers = NULL; } spin_lock(&journal->j_list_lock); diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index e70d657a19f..f6bff9d6f8d 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -50,6 +50,7 @@ EXPORT_SYMBOL(jbd2_journal_unlock_updates); EXPORT_SYMBOL(jbd2_journal_get_write_access); EXPORT_SYMBOL(jbd2_journal_get_create_access); EXPORT_SYMBOL(jbd2_journal_get_undo_access); +EXPORT_SYMBOL(jbd2_journal_set_triggers); EXPORT_SYMBOL(jbd2_journal_dirty_metadata); EXPORT_SYMBOL(jbd2_journal_release_buffer); EXPORT_SYMBOL(jbd2_journal_forget); @@ -290,6 +291,7 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction, struct page *new_page; unsigned int new_offset; struct buffer_head *bh_in = jh2bh(jh_in); + struct jbd2_buffer_trigger_type *triggers; /* * The buffer really shouldn't be locked: only the current committing @@ -314,12 +316,22 @@ repeat: done_copy_out = 1; new_page = virt_to_page(jh_in->b_frozen_data); new_offset = offset_in_page(jh_in->b_frozen_data); + triggers = jh_in->b_frozen_triggers; } else { new_page = jh2bh(jh_in)->b_page; new_offset = offset_in_page(jh2bh(jh_in)->b_data); + triggers = jh_in->b_triggers; } mapped_data = kmap_atomic(new_page, KM_USER0); + /* + * Fire any commit trigger. Do this before checking for escaping, + * as the trigger may modify the magic offset. If a copy-out + * happens afterwards, it will have the correct data in the buffer. + */ + jbd2_buffer_commit_trigger(jh_in, mapped_data + new_offset, + triggers); + /* * Check for escaping */ @@ -352,6 +364,13 @@ repeat: new_page = virt_to_page(tmp); new_offset = offset_in_page(tmp); done_copy_out = 1; + + /* + * This isn't strictly necessary, as we're using frozen + * data for the escaping, but it keeps consistency with + * b_frozen_data usage. + */ + jh_in->b_frozen_triggers = jh_in->b_triggers; } /* diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c index 39b7805a599..4f925a4f3d0 100644 --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -741,6 +741,12 @@ done: source = kmap_atomic(page, KM_USER0); memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size); kunmap_atomic(source, KM_USER0); + + /* + * Now that the frozen data is saved off, we need to store + * any matching triggers. + */ + jh->b_frozen_triggers = jh->b_triggers; } jbd_unlock_bh_state(bh); @@ -943,6 +949,47 @@ out: return err; } +/** + * void jbd2_journal_set_triggers() - Add triggers for commit writeout + * @bh: buffer to trigger on + * @type: struct jbd2_buffer_trigger_type containing the trigger(s). + * + * Set any triggers on this journal_head. This is always safe, because + * triggers for a committing buffer will be saved off, and triggers for + * a running transaction will match the buffer in that transaction. + * + * Call with NULL to clear the triggers. + */ +void jbd2_journal_set_triggers(struct buffer_head *bh, + struct jbd2_buffer_trigger_type *type) +{ + struct journal_head *jh = bh2jh(bh); + + jh->b_triggers = type; +} + +void jbd2_buffer_commit_trigger(struct journal_head *jh, void *mapped_data, + struct jbd2_buffer_trigger_type *triggers) +{ + struct buffer_head *bh = jh2bh(jh); + + if (!triggers || !triggers->t_commit) + return; + + triggers->t_commit(triggers, bh, mapped_data, bh->b_size); +} + +void jbd2_buffer_abort_trigger(struct journal_head *jh, + struct jbd2_buffer_trigger_type *triggers) +{ + if (!triggers || !triggers->t_abort) + return; + + triggers->t_abort(triggers, jh2bh(jh)); +} + + + /** * int jbd2_journal_dirty_metadata() - mark a buffer as containing dirty metadata * @handle: transaction to add buffer to. -- cgit v1.2.3