From 1ba37268cd19e5a2a80924bfe8618bf1ba3e8249 Mon Sep 17 00:00:00 2001 From: Yongqiang Yang Date: Wed, 28 Dec 2011 17:46:46 -0500 Subject: jbd2: clear revoked flag on buffers before a new transaction started Currently, we clear revoked flag only when a block is reused. However, this can tigger a false journal error. Consider a situation when a block is used as a meta block and is deleted(revoked) in ordered mode, then the block is allocated as a data block to a file. At this moment, user changes the file's journal mode from ordered to journaled and truncates the file. The block will be considered re-revoked by journal because it has revoked flag still pending from the last transaction and an assertion triggers. We fix the problem by keeping the revoked status more uptodate - we clear revoked flag when switching revoke tables to reflect there is no revoked buffers in current transaction any more. Signed-off-by: Yongqiang Yang Signed-off-by: "Theodore Ts'o" --- fs/jbd2/commit.c | 6 ++++++ fs/jbd2/revoke.c | 34 ++++++++++++++++++++++++++++++++++ 2 files changed, 40 insertions(+) (limited to 'fs/jbd2') diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c index 68d704db787..5069b847515 100644 --- a/fs/jbd2/commit.c +++ b/fs/jbd2/commit.c @@ -429,6 +429,12 @@ void jbd2_journal_commit_transaction(journal_t *journal) jbd_debug(3, "JBD2: commit phase 1\n"); + /* + * Clear revoked flag to reflect there is no revoked buffers + * in the next transaction which is going to be started. + */ + jbd2_clear_buffer_revoked_flags(journal); + /* * Switch to a new revoke table. */ diff --git a/fs/jbd2/revoke.c b/fs/jbd2/revoke.c index 69fd9358811..30b2867d6cc 100644 --- a/fs/jbd2/revoke.c +++ b/fs/jbd2/revoke.c @@ -47,6 +47,10 @@ * overwriting the new data. We don't even need to clear the revoke * bit here. * + * We cache revoke status of a buffer in the current transaction in b_states + * bits. As the name says, revokevalid flag indicates that the cached revoke + * status of a buffer is valid and we can rely on the cached status. + * * Revoke information on buffers is a tri-state value: * * RevokeValid clear: no cached revoke status, need to look it up @@ -478,6 +482,36 @@ int jbd2_journal_cancel_revoke(handle_t *handle, struct journal_head *jh) return did_revoke; } +/* + * journal_clear_revoked_flag clears revoked flag of buffers in + * revoke table to reflect there is no revoked buffers in the next + * transaction which is going to be started. + */ +void jbd2_clear_buffer_revoked_flags(journal_t *journal) +{ + struct jbd2_revoke_table_s *revoke = journal->j_revoke; + int i = 0; + + for (i = 0; i < revoke->hash_size; i++) { + struct list_head *hash_list; + struct list_head *list_entry; + hash_list = &revoke->hash_table[i]; + + list_for_each(list_entry, hash_list) { + struct jbd2_revoke_record_s *record; + struct buffer_head *bh; + record = (struct jbd2_revoke_record_s *)list_entry; + bh = __find_get_block(journal->j_fs_dev, + record->blocknr, + journal->j_blocksize); + if (bh) { + clear_buffer_revoked(bh); + __brelse(bh); + } + } + } +} + /* journal_switch_revoke table select j_revoke for next transaction * we do not want to suspend any processing until all revokes are * written -bzzz -- cgit v1.2.3 From 9837d8e982b7e87a7207f90618e45d460e196e6a Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Wed, 4 Jan 2012 22:03:11 -0500 Subject: jbd2: fix hung processes in jbd2_journal_lock_updates() Toshiyuki Okajima found out that when running for ((i=0; i < 100000; i++)); do if ((i%2 == 0)); then chattr +j /mnt/file else chattr -j /mnt/file fi echo "0" >> /mnt/file done process sometimes hangs indefinitely in jbd2_journal_lock_updates(). Toshiyuki identified that the following race happens: jbd2_journal_lock_updates() |jbd2_journal_stop() ---------------------------------------+--------------------------------------- write_lock(&journal->j_state_lock) | . ++journal->j_barrier_count | . spin_lock(&tran->t_handle_lock) | . atomic_read(&tran->t_updates) //not 0 | | atomic_dec_and_test(&tran->t_updates) | // t_updates = 0 | wake_up(&journal->j_wait_updates) prepare_to_wait() | // no process is woken up. spin_unlock(&tran->t_handle_lock) | write_unlock(&journal->j_state_lock) | schedule() // never return | We fix the problem by first calling prepare_to_wait() and only after that checking t_updates in jbd2_journal_lock_updates(). Reported-and-analyzed-by: Toshiyuki Okajima Signed-off-by: Jan Kara Signed-off-by: "Theodore Ts'o" --- fs/jbd2/transaction.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'fs/jbd2') diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c index a0e41a4c080..35ae096bed5 100644 --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -517,12 +517,13 @@ void jbd2_journal_lock_updates(journal_t *journal) break; spin_lock(&transaction->t_handle_lock); + prepare_to_wait(&journal->j_wait_updates, &wait, + TASK_UNINTERRUPTIBLE); if (!atomic_read(&transaction->t_updates)) { spin_unlock(&transaction->t_handle_lock); + finish_wait(&journal->j_wait_updates, &wait); break; } - prepare_to_wait(&journal->j_wait_updates, &wait, - TASK_UNINTERRUPTIBLE); spin_unlock(&transaction->t_handle_lock); write_unlock(&journal->j_state_lock); schedule(); -- cgit v1.2.3