From 39e3ac2599a5f9aba499b5f8af809108e70a6163 Mon Sep 17 00:00:00 2001 From: Brian King Date: Wed, 27 Oct 2010 21:25:12 -0400 Subject: [PATCH] jbd2: Fix I/O hang in jbd2_journal_release_jbd_inode This fixes a hang seen in jbd2_journal_release_jbd_inode on a lot of Power 6 systems running with ext4. When we get in the hung state, all I/O to the disk in question gets blocked where we stay indefinitely. Looking at the task list, I can see we are stuck in jbd2_journal_release_jbd_inode waiting on a wake up. I added some debug code to detect this scenario and dump additional data if we were stuck in jbd2_journal_release_jbd_inode for longer than 30 minutes. When it hit, I was able to see that i_flags was 0, suggesting we missed the wake up. This patch changes i_flags to be an unsigned long, uses bit operators to access it, and adds barriers around the accesses. Prior to applying this patch, we were regularly hitting this hang on numerous systems in our test environment. After applying the patch, the hangs no longer occur. Signed-off-by: Brian King Signed-off-by: "Theodore Ts'o" --- fs/jbd2/commit.c | 12 ++++++++---- fs/jbd2/journal.c | 4 +++- include/linux/jbd2.h | 2 +- 3 files changed, 12 insertions(+), 6 deletions(-) diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c index 7c068c189d80..6494c81e3b0a 100644 --- a/fs/jbd2/commit.c +++ b/fs/jbd2/commit.c @@ -26,7 +26,9 @@ #include #include #include +#include #include +#include /* * Default IO end handler for temporary BJ_IO buffer_heads. @@ -236,7 +238,7 @@ static int journal_submit_data_buffers(journal_t *journal, spin_lock(&journal->j_list_lock); list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) { mapping = jinode->i_vfs_inode->i_mapping; - jinode->i_flags |= JI_COMMIT_RUNNING; + set_bit(__JI_COMMIT_RUNNING, &jinode->i_flags); spin_unlock(&journal->j_list_lock); /* * submit the inode data buffers. We use writepage @@ -251,7 +253,8 @@ static int journal_submit_data_buffers(journal_t *journal, spin_lock(&journal->j_list_lock); J_ASSERT(jinode->i_transaction == commit_transaction); commit_transaction->t_flushed_data_blocks = 1; - jinode->i_flags &= ~JI_COMMIT_RUNNING; + clear_bit(__JI_COMMIT_RUNNING, &jinode->i_flags); + smp_mb__after_clear_bit(); wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING); } spin_unlock(&journal->j_list_lock); @@ -272,7 +275,7 @@ static int journal_finish_inode_data_buffers(journal_t *journal, /* For locking, see the comment in journal_submit_data_buffers() */ spin_lock(&journal->j_list_lock); list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) { - jinode->i_flags |= JI_COMMIT_RUNNING; + set_bit(__JI_COMMIT_RUNNING, &jinode->i_flags); spin_unlock(&journal->j_list_lock); err = filemap_fdatawait(jinode->i_vfs_inode->i_mapping); if (err) { @@ -288,7 +291,8 @@ static int journal_finish_inode_data_buffers(journal_t *journal, ret = err; } spin_lock(&journal->j_list_lock); - jinode->i_flags &= ~JI_COMMIT_RUNNING; + clear_bit(__JI_COMMIT_RUNNING, &jinode->i_flags); + smp_mb__after_clear_bit(); wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING); } diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index 0e8014ea6b94..75e1b5a0bc2d 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -42,12 +42,14 @@ #include #include #include +#include #define CREATE_TRACE_POINTS #include #include #include +#include EXPORT_SYMBOL(jbd2_journal_extend); EXPORT_SYMBOL(jbd2_journal_stop); @@ -2206,7 +2208,7 @@ void jbd2_journal_release_jbd_inode(journal_t *journal, restart: spin_lock(&journal->j_list_lock); /* Is commit writing out inode - we have to wait */ - if (jinode->i_flags & JI_COMMIT_RUNNING) { + if (test_bit(__JI_COMMIT_RUNNING, &jinode->i_flags)) { wait_queue_head_t *wq; DEFINE_WAIT_BIT(wait, &jinode->i_flags, __JI_COMMIT_RUNNING); wq = bit_waitqueue(&jinode->i_flags, __JI_COMMIT_RUNNING); diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h index 0b52924a0cb6..2ae86aa21fce 100644 --- a/include/linux/jbd2.h +++ b/include/linux/jbd2.h @@ -395,7 +395,7 @@ struct jbd2_inode { struct inode *i_vfs_inode; /* Flags of inode [j_list_lock] */ - unsigned int i_flags; + unsigned long i_flags; }; struct jbd2_revoke_table_s; -- 2.20.1