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authorToshiyuki Okajima <toshi.okajima@jp.fujitsu.com>2008-07-25 01:46:29 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-25 10:53:32 -0700
commitfc80c44277b3c92d808b73e9d40e120229aa4b6a (patch)
treedb0848f89305aa3c90b07ad773badc17f858405e /fs/ext3/namei.c
parenta10320e8f7c4dcfa050aac566092f29b40458d5a (diff)
jbd: positively dispose the unmapped data buffers in journal_commit_transaction()
After ext3-ordered files are truncated, there is a possibility that the pages which cannot be estimated still remain. Remaining pages can be released when the system has really few memory. So, it is not memory leakage. But the resource management software etc. may not work correctly. It is possible that journal_unmap_buffer() cannot release the buffers, and the pages to which they belong because they are attached to a commiting transaction and journal_unmap_buffer() cannot release them. To release such the buffers and the pages later, journal_unmap_buffer() leaves it to journal_commit_transaction(). (journal_unmap_buffer() puts the mark 'BH_Freed' to the buffers so that journal_commit_transaction() can identify whether they can be released or not.) In the journalled mode and the writeback mode, jbd does with only metadata buffers. But in the ordered mode, jbd does with metadata buffers and also data buffers. Actually, journal_commit_transaction() releases only the metadata buffers of which release is demanded by journal_unmap_buffer(), and also releases the pages to which they belong if possible. As a result, the data buffers of which release is demanded by journal_unmap_buffer() remain after a transaction commits. And also the pages to which they belong remain. Such the remained pages don't have mapping any longer. Due to this fact, there is a possibility that the pages which cannot be estimated remain. The metadata buffers marked 'BH_Freed' and the pages to which they belong can be released at 'JBD: commit phase 7'. Therefore, by applying the same code into 'JBD: commit phase 2' (where the data buffers are done with), journal_commit_transaction() can also release the data buffers marked 'BH_Freed' and the pages to which they belong. As a result, all the buffers marked 'BH_Freed' can be released, and also all the pages to which these buffers belong can be released at journal_commit_transaction(). So, the page which cannot be estimated is lost. <<Excerpt of code at 'JBD: commit phase 7'>> > spin_lock(&journal->j_list_lock); > while (commit_transaction->t_forget) { > transaction_t *cp_transaction; > struct buffer_head *bh; > > jh = commit_transaction->t_forget; >... > if (buffer_freed(bh)) { > ^^^^^^^^^^^^^^^^^^^^^^^^ > clear_buffer_freed(bh); > ^^^^^^^^^^^^^^^^^^^^^^^^ > clear_buffer_jbddirty(bh); > } > > if (buffer_jbddirty(bh)) { > JBUFFER_TRACE(jh, "add to new checkpointing trans"); > __journal_insert_checkpoint(jh, commit_transaction); > JBUFFER_TRACE(jh, "refile for checkpoint writeback"); > __journal_refile_buffer(jh); > jbd_unlock_bh_state(bh); > } else { > J_ASSERT_BH(bh, !buffer_dirty(bh)); > ... > JBUFFER_TRACE(jh, "refile or unfile freed buffer"); > __journal_refile_buffer(jh); > if (!jh->b_transaction) { > jbd_unlock_bh_state(bh); > /* needs a brelse */ > journal_remove_journal_head(bh); > release_buffer_page(bh); > ^^^^^^^^^^^^^^^^^^^^^^^^ > } else > } **************************************************************** * Apply the code of "^^^^^^" lines into 'JBD: commit phase 2' * **************************************************************** At journal_commit_transaction() code, there is one extra message in the series of jbd debug messages. ("JBD: commit phase 2") This patch fixes it, too. Signed-off-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com> Acked-by: Jan Kara <jack@suse.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/ext3/namei.c')
0 files changed, 0 insertions, 0 deletions