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authorToshiyuki Okajima <toshi.okajima@jp.fujitsu.com>2008-07-25 04:46:29 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-25 13:53:32 -0400
commitfc80c44277b3c92d808b73e9d40e120229aa4b6a (patch)
treedb0848f89305aa3c90b07ad773badc17f858405e /fs
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')
-rw-r--r--fs/jbd/commit.c29
1 files changed, 20 insertions, 9 deletions
diff --git a/fs/jbd/commit.c b/fs/jbd/commit.c
index 5a8ca61498ca..f943b9b3f208 100644
--- a/fs/jbd/commit.c
+++ b/fs/jbd/commit.c
@@ -36,7 +36,7 @@ static void journal_end_buffer_io_sync(struct buffer_head *bh, int uptodate)
36 36
37/* 37/*
38 * When an ext3-ordered file is truncated, it is possible that many pages are 38 * When an ext3-ordered file is truncated, it is possible that many pages are
39 * not sucessfully freed, because they are attached to a committing transaction. 39 * not successfully freed, because they are attached to a committing transaction.
40 * After the transaction commits, these pages are left on the LRU, with no 40 * After the transaction commits, these pages are left on the LRU, with no
41 * ->mapping, and with attached buffers. These pages are trivially reclaimable 41 * ->mapping, and with attached buffers. These pages are trivially reclaimable
42 * by the VM, but their apparent absence upsets the VM accounting, and it makes 42 * by the VM, but their apparent absence upsets the VM accounting, and it makes
@@ -45,8 +45,8 @@ static void journal_end_buffer_io_sync(struct buffer_head *bh, int uptodate)
45 * So here, we have a buffer which has just come off the forget list. Look to 45 * So here, we have a buffer which has just come off the forget list. Look to
46 * see if we can strip all buffers from the backing page. 46 * see if we can strip all buffers from the backing page.
47 * 47 *
48 * Called under lock_journal(), and possibly under journal_datalist_lock. The 48 * Called under journal->j_list_lock. The caller provided us with a ref
49 * caller provided us with a ref against the buffer, and we drop that here. 49 * against the buffer, and we drop that here.
50 */ 50 */
51static void release_buffer_page(struct buffer_head *bh) 51static void release_buffer_page(struct buffer_head *bh)
52{ 52{
@@ -78,6 +78,19 @@ nope:
78} 78}
79 79
80/* 80/*
81 * Decrement reference counter for data buffer. If it has been marked
82 * 'BH_Freed', release it and the page to which it belongs if possible.
83 */
84static void release_data_buffer(struct buffer_head *bh)
85{
86 if (buffer_freed(bh)) {
87 clear_buffer_freed(bh);
88 release_buffer_page(bh);
89 } else
90 put_bh(bh);
91}
92
93/*
81 * Try to acquire jbd_lock_bh_state() against the buffer, when j_list_lock is 94 * Try to acquire jbd_lock_bh_state() against the buffer, when j_list_lock is
82 * held. For ranking reasons we must trylock. If we lose, schedule away and 95 * held. For ranking reasons we must trylock. If we lose, schedule away and
83 * return 0. j_list_lock is dropped in this case. 96 * return 0. j_list_lock is dropped in this case.
@@ -231,7 +244,7 @@ write_out_data:
231 if (locked) 244 if (locked)
232 unlock_buffer(bh); 245 unlock_buffer(bh);
233 BUFFER_TRACE(bh, "already cleaned up"); 246 BUFFER_TRACE(bh, "already cleaned up");
234 put_bh(bh); 247 release_data_buffer(bh);
235 continue; 248 continue;
236 } 249 }
237 if (locked && test_clear_buffer_dirty(bh)) { 250 if (locked && test_clear_buffer_dirty(bh)) {
@@ -258,10 +271,10 @@ write_out_data:
258 if (locked) 271 if (locked)
259 unlock_buffer(bh); 272 unlock_buffer(bh);
260 journal_remove_journal_head(bh); 273 journal_remove_journal_head(bh);
261 /* Once for our safety reference, once for 274 /* One for our safety reference, other for
262 * journal_remove_journal_head() */ 275 * journal_remove_journal_head() */
263 put_bh(bh); 276 put_bh(bh);
264 put_bh(bh); 277 release_data_buffer(bh);
265 } 278 }
266 279
267 if (need_resched() || spin_needbreak(&journal->j_list_lock)) { 280 if (need_resched() || spin_needbreak(&journal->j_list_lock)) {
@@ -443,7 +456,7 @@ void journal_commit_transaction(journal_t *journal)
443 } else { 456 } else {
444 jbd_unlock_bh_state(bh); 457 jbd_unlock_bh_state(bh);
445 } 458 }
446 put_bh(bh); 459 release_data_buffer(bh);
447 cond_resched_lock(&journal->j_list_lock); 460 cond_resched_lock(&journal->j_list_lock);
448 } 461 }
449 spin_unlock(&journal->j_list_lock); 462 spin_unlock(&journal->j_list_lock);
@@ -453,8 +466,6 @@ void journal_commit_transaction(journal_t *journal)
453 466
454 journal_write_revoke_records(journal, commit_transaction); 467 journal_write_revoke_records(journal, commit_transaction);
455 468
456 jbd_debug(3, "JBD: commit phase 2\n");
457
458 /* 469 /*
459 * If we found any dirty or locked buffers, then we should have 470 * If we found any dirty or locked buffers, then we should have
460 * looped back up to the write_out_data label. If there weren't 471 * looped back up to the write_out_data label. If there weren't