| Message ID | 20181121190922.25038-4-josef@toxicpanda.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Delayed iput fixes | expand |
On 21.11.18 г. 21:09 ч., Josef Bacik wrote: > The throttle path doesn't take cleaner_delayed_iput_mutex, which means Which one is the throttle path? btrfs_end_transaction_throttle is only called during snapshot drop and relocation? What scenario triggered your observation and prompted this fix? > we could think we're done flushing iputs in the data space reservation > path when we could have a throttler doing an iput. There's no real > reason to serialize the delayed iput flushing, so instead of taking the > cleaner_delayed_iput_mutex whenever we flush the delayed iputs just > replace it with an atomic counter and a waitqueue. This removes the > short (or long depending on how big the inode is) window where we think > there are no more pending iputs when there really are some. > > Signed-off-by: Josef Bacik <josef@toxicpanda.com> > --- > fs/btrfs/ctree.h | 4 +++- > fs/btrfs/disk-io.c | 5 ++--- > fs/btrfs/extent-tree.c | 9 +++++---- > fs/btrfs/inode.c | 21 +++++++++++++++++++++ > 4 files changed, 31 insertions(+), 8 deletions(-) > > diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h > index 709de7471d86..a835fe7076eb 100644 > --- a/fs/btrfs/ctree.h > +++ b/fs/btrfs/ctree.h > @@ -912,7 +912,8 @@ struct btrfs_fs_info { > > spinlock_t delayed_iput_lock; > struct list_head delayed_iputs; > - struct mutex cleaner_delayed_iput_mutex; > + atomic_t nr_delayed_iputs; > + wait_queue_head_t delayed_iputs_wait; > > /* this protects tree_mod_seq_list */ > spinlock_t tree_mod_seq_lock; > @@ -3237,6 +3238,7 @@ int btrfs_orphan_cleanup(struct btrfs_root *root); > int btrfs_cont_expand(struct inode *inode, loff_t oldsize, loff_t size); > void btrfs_add_delayed_iput(struct inode *inode); > void btrfs_run_delayed_iputs(struct btrfs_fs_info *fs_info); > +int btrfs_wait_on_delayed_iputs(struct btrfs_fs_info *fs_info); > int btrfs_prealloc_file_range(struct inode *inode, int mode, > u64 start, u64 num_bytes, u64 min_size, > loff_t actual_len, u64 *alloc_hint); > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > index c5918ff8241b..3f81dfaefa32 100644 > --- a/fs/btrfs/disk-io.c > +++ b/fs/btrfs/disk-io.c > @@ -1692,9 +1692,7 @@ static int cleaner_kthread(void *arg) > goto sleep; > } > > - mutex_lock(&fs_info->cleaner_delayed_iput_mutex); > btrfs_run_delayed_iputs(fs_info); > - mutex_unlock(&fs_info->cleaner_delayed_iput_mutex); > > again = btrfs_clean_one_deleted_snapshot(root); > mutex_unlock(&fs_info->cleaner_mutex); > @@ -2651,7 +2649,6 @@ int open_ctree(struct super_block *sb, > mutex_init(&fs_info->delete_unused_bgs_mutex); > mutex_init(&fs_info->reloc_mutex); > mutex_init(&fs_info->delalloc_root_mutex); > - mutex_init(&fs_info->cleaner_delayed_iput_mutex); > seqlock_init(&fs_info->profiles_lock); > > INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots); > @@ -2673,6 +2670,7 @@ int open_ctree(struct super_block *sb, > atomic_set(&fs_info->defrag_running, 0); > atomic_set(&fs_info->qgroup_op_seq, 0); > atomic_set(&fs_info->reada_works_cnt, 0); > + atomic_set(&fs_info->nr_delayed_iputs, 0); > atomic64_set(&fs_info->tree_mod_seq, 0); > fs_info->sb = sb; > fs_info->max_inline = BTRFS_DEFAULT_MAX_INLINE; > @@ -2750,6 +2748,7 @@ int open_ctree(struct super_block *sb, > init_waitqueue_head(&fs_info->transaction_wait); > init_waitqueue_head(&fs_info->transaction_blocked_wait); > init_waitqueue_head(&fs_info->async_submit_wait); > + init_waitqueue_head(&fs_info->delayed_iputs_wait); > > INIT_LIST_HEAD(&fs_info->pinned_chunks); > > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c > index 3a90dc1d6b31..36f43876be22 100644 > --- a/fs/btrfs/extent-tree.c > +++ b/fs/btrfs/extent-tree.c > @@ -4272,8 +4272,9 @@ int btrfs_alloc_data_chunk_ondemand(struct btrfs_inode *inode, u64 bytes) > * operations. Wait for it to finish so that > * more space is released. > */ > - mutex_lock(&fs_info->cleaner_delayed_iput_mutex); > - mutex_unlock(&fs_info->cleaner_delayed_iput_mutex); > + ret = btrfs_wait_on_delayed_iputs(fs_info); > + if (ret) > + return ret; > goto again; > } else { > btrfs_end_transaction(trans); > @@ -4838,9 +4839,9 @@ static int may_commit_transaction(struct btrfs_fs_info *fs_info, > * pinned space, so make sure we run the iputs before we do our pinned > * bytes check below. > */ > - mutex_lock(&fs_info->cleaner_delayed_iput_mutex); > btrfs_run_delayed_iputs(fs_info); > - mutex_unlock(&fs_info->cleaner_delayed_iput_mutex); > + wait_event(fs_info->delayed_iputs_wait, > + atomic_read(&fs_info->nr_delayed_iputs) == 0); Why open code btrfs_wait_on_delayed_iputs(fs_info)? Just make it use wait_event instead of the killable version and use the function uniformally across the code base. > > trans = btrfs_join_transaction(fs_info->extent_root); > if (IS_ERR(trans)) > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index 3c42d8887183..57bf514a90eb 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -3260,6 +3260,7 @@ void btrfs_add_delayed_iput(struct inode *inode) > if (atomic_add_unless(&inode->i_count, -1, 1)) > return; > > + atomic_inc(&fs_info->nr_delayed_iputs); > spin_lock(&fs_info->delayed_iput_lock); > ASSERT(list_empty(&binode->delayed_iput)); > list_add_tail(&binode->delayed_iput, &fs_info->delayed_iputs); > @@ -3279,11 +3280,31 @@ void btrfs_run_delayed_iputs(struct btrfs_fs_info *fs_info) > list_del_init(&inode->delayed_iput); > spin_unlock(&fs_info->delayed_iput_lock); > iput(&inode->vfs_inode); > + if (atomic_dec_and_test(&fs_info->nr_delayed_iputs)) > + wake_up(&fs_info->delayed_iputs_wait); > spin_lock(&fs_info->delayed_iput_lock); > } > spin_unlock(&fs_info->delayed_iput_lock); > } > > +/** > + * btrfs_wait_on_delayed_iputs - wait on the delayed iputs to be done running > + * @fs_info - the fs_info for this fs > + * @return - EINTR if we were killed, 0 if nothing's pending > + * > + * This will wait on any delayed iputs that are currently running with KILLABLE > + * set. Once they are all done running we will return, unless we are killed in > + * which case we return EINTR. > + */ > +int btrfs_wait_on_delayed_iputs(struct btrfs_fs_info *fs_info) > +{ > + int ret = wait_event_killable(fs_info->delayed_iputs_wait, > + atomic_read(&fs_info->nr_delayed_iputs) == 0); > + if (ret) > + return -EINTR; > + return 0; > +} > + > /* > * This creates an orphan entry for the given inode in case something goes wrong > * in the middle of an unlink. >
On Tue, Nov 27, 2018 at 10:29:57AM +0200, Nikolay Borisov wrote: > > > On 21.11.18 г. 21:09 ч., Josef Bacik wrote: > > The throttle path doesn't take cleaner_delayed_iput_mutex, which means > > Which one is the throttle path? btrfs_end_transaction_throttle is only > called during snapshot drop and relocation? What scenario triggered your > observation and prompted this fix? > One of my enospc tests runs snapshot creation/deletion in the background. > > we could think we're done flushing iputs in the data space reservation > > path when we could have a throttler doing an iput. There's no real > > reason to serialize the delayed iput flushing, so instead of taking the > > cleaner_delayed_iput_mutex whenever we flush the delayed iputs just > > replace it with an atomic counter and a waitqueue. This removes the > > short (or long depending on how big the inode is) window where we think > > there are no more pending iputs when there really are some. > > > > Signed-off-by: Josef Bacik <josef@toxicpanda.com> > > --- > > fs/btrfs/ctree.h | 4 +++- > > fs/btrfs/disk-io.c | 5 ++--- > > fs/btrfs/extent-tree.c | 9 +++++---- > > fs/btrfs/inode.c | 21 +++++++++++++++++++++ > > 4 files changed, 31 insertions(+), 8 deletions(-) > > > > diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h > > index 709de7471d86..a835fe7076eb 100644 > > --- a/fs/btrfs/ctree.h > > +++ b/fs/btrfs/ctree.h > > @@ -912,7 +912,8 @@ struct btrfs_fs_info { > > > > spinlock_t delayed_iput_lock; > > struct list_head delayed_iputs; > > - struct mutex cleaner_delayed_iput_mutex; > > + atomic_t nr_delayed_iputs; > > + wait_queue_head_t delayed_iputs_wait; > > > > /* this protects tree_mod_seq_list */ > > spinlock_t tree_mod_seq_lock; > > @@ -3237,6 +3238,7 @@ int btrfs_orphan_cleanup(struct btrfs_root *root); > > int btrfs_cont_expand(struct inode *inode, loff_t oldsize, loff_t size); > > void btrfs_add_delayed_iput(struct inode *inode); > > void btrfs_run_delayed_iputs(struct btrfs_fs_info *fs_info); > > +int btrfs_wait_on_delayed_iputs(struct btrfs_fs_info *fs_info); > > int btrfs_prealloc_file_range(struct inode *inode, int mode, > > u64 start, u64 num_bytes, u64 min_size, > > loff_t actual_len, u64 *alloc_hint); > > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > > index c5918ff8241b..3f81dfaefa32 100644 > > --- a/fs/btrfs/disk-io.c > > +++ b/fs/btrfs/disk-io.c > > @@ -1692,9 +1692,7 @@ static int cleaner_kthread(void *arg) > > goto sleep; > > } > > > > - mutex_lock(&fs_info->cleaner_delayed_iput_mutex); > > btrfs_run_delayed_iputs(fs_info); > > - mutex_unlock(&fs_info->cleaner_delayed_iput_mutex); > > > > again = btrfs_clean_one_deleted_snapshot(root); > > mutex_unlock(&fs_info->cleaner_mutex); > > @@ -2651,7 +2649,6 @@ int open_ctree(struct super_block *sb, > > mutex_init(&fs_info->delete_unused_bgs_mutex); > > mutex_init(&fs_info->reloc_mutex); > > mutex_init(&fs_info->delalloc_root_mutex); > > - mutex_init(&fs_info->cleaner_delayed_iput_mutex); > > seqlock_init(&fs_info->profiles_lock); > > > > INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots); > > @@ -2673,6 +2670,7 @@ int open_ctree(struct super_block *sb, > > atomic_set(&fs_info->defrag_running, 0); > > atomic_set(&fs_info->qgroup_op_seq, 0); > > atomic_set(&fs_info->reada_works_cnt, 0); > > + atomic_set(&fs_info->nr_delayed_iputs, 0); > > atomic64_set(&fs_info->tree_mod_seq, 0); > > fs_info->sb = sb; > > fs_info->max_inline = BTRFS_DEFAULT_MAX_INLINE; > > @@ -2750,6 +2748,7 @@ int open_ctree(struct super_block *sb, > > init_waitqueue_head(&fs_info->transaction_wait); > > init_waitqueue_head(&fs_info->transaction_blocked_wait); > > init_waitqueue_head(&fs_info->async_submit_wait); > > + init_waitqueue_head(&fs_info->delayed_iputs_wait); > > > > INIT_LIST_HEAD(&fs_info->pinned_chunks); > > > > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c > > index 3a90dc1d6b31..36f43876be22 100644 > > --- a/fs/btrfs/extent-tree.c > > +++ b/fs/btrfs/extent-tree.c > > @@ -4272,8 +4272,9 @@ int btrfs_alloc_data_chunk_ondemand(struct btrfs_inode *inode, u64 bytes) > > * operations. Wait for it to finish so that > > * more space is released. > > */ > > - mutex_lock(&fs_info->cleaner_delayed_iput_mutex); > > - mutex_unlock(&fs_info->cleaner_delayed_iput_mutex); > > + ret = btrfs_wait_on_delayed_iputs(fs_info); > > + if (ret) > > + return ret; > > goto again; > > } else { > > btrfs_end_transaction(trans); > > @@ -4838,9 +4839,9 @@ static int may_commit_transaction(struct btrfs_fs_info *fs_info, > > * pinned space, so make sure we run the iputs before we do our pinned > > * bytes check below. > > */ > > - mutex_lock(&fs_info->cleaner_delayed_iput_mutex); > > btrfs_run_delayed_iputs(fs_info); > > - mutex_unlock(&fs_info->cleaner_delayed_iput_mutex); > > + wait_event(fs_info->delayed_iputs_wait, > > + atomic_read(&fs_info->nr_delayed_iputs) == 0); > > Why open code btrfs_wait_on_delayed_iputs(fs_info)? Just make it use > wait_event instead of the killable version and use the function > uniformally across the code base. I don't want the flusher thread to be killable, but now that I've said that out loud I realize that's not possible, so I'll just use the helper. Thanks, Josef
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 709de7471d86..a835fe7076eb 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -912,7 +912,8 @@ struct btrfs_fs_info { spinlock_t delayed_iput_lock; struct list_head delayed_iputs; - struct mutex cleaner_delayed_iput_mutex; + atomic_t nr_delayed_iputs; + wait_queue_head_t delayed_iputs_wait; /* this protects tree_mod_seq_list */ spinlock_t tree_mod_seq_lock; @@ -3237,6 +3238,7 @@ int btrfs_orphan_cleanup(struct btrfs_root *root); int btrfs_cont_expand(struct inode *inode, loff_t oldsize, loff_t size); void btrfs_add_delayed_iput(struct inode *inode); void btrfs_run_delayed_iputs(struct btrfs_fs_info *fs_info); +int btrfs_wait_on_delayed_iputs(struct btrfs_fs_info *fs_info); int btrfs_prealloc_file_range(struct inode *inode, int mode, u64 start, u64 num_bytes, u64 min_size, loff_t actual_len, u64 *alloc_hint); diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index c5918ff8241b..3f81dfaefa32 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1692,9 +1692,7 @@ static int cleaner_kthread(void *arg) goto sleep; } - mutex_lock(&fs_info->cleaner_delayed_iput_mutex); btrfs_run_delayed_iputs(fs_info); - mutex_unlock(&fs_info->cleaner_delayed_iput_mutex); again = btrfs_clean_one_deleted_snapshot(root); mutex_unlock(&fs_info->cleaner_mutex); @@ -2651,7 +2649,6 @@ int open_ctree(struct super_block *sb, mutex_init(&fs_info->delete_unused_bgs_mutex); mutex_init(&fs_info->reloc_mutex); mutex_init(&fs_info->delalloc_root_mutex); - mutex_init(&fs_info->cleaner_delayed_iput_mutex); seqlock_init(&fs_info->profiles_lock); INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots); @@ -2673,6 +2670,7 @@ int open_ctree(struct super_block *sb, atomic_set(&fs_info->defrag_running, 0); atomic_set(&fs_info->qgroup_op_seq, 0); atomic_set(&fs_info->reada_works_cnt, 0); + atomic_set(&fs_info->nr_delayed_iputs, 0); atomic64_set(&fs_info->tree_mod_seq, 0); fs_info->sb = sb; fs_info->max_inline = BTRFS_DEFAULT_MAX_INLINE; @@ -2750,6 +2748,7 @@ int open_ctree(struct super_block *sb, init_waitqueue_head(&fs_info->transaction_wait); init_waitqueue_head(&fs_info->transaction_blocked_wait); init_waitqueue_head(&fs_info->async_submit_wait); + init_waitqueue_head(&fs_info->delayed_iputs_wait); INIT_LIST_HEAD(&fs_info->pinned_chunks); diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 3a90dc1d6b31..36f43876be22 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -4272,8 +4272,9 @@ int btrfs_alloc_data_chunk_ondemand(struct btrfs_inode *inode, u64 bytes) * operations. Wait for it to finish so that * more space is released. */ - mutex_lock(&fs_info->cleaner_delayed_iput_mutex); - mutex_unlock(&fs_info->cleaner_delayed_iput_mutex); + ret = btrfs_wait_on_delayed_iputs(fs_info); + if (ret) + return ret; goto again; } else { btrfs_end_transaction(trans); @@ -4838,9 +4839,9 @@ static int may_commit_transaction(struct btrfs_fs_info *fs_info, * pinned space, so make sure we run the iputs before we do our pinned * bytes check below. */ - mutex_lock(&fs_info->cleaner_delayed_iput_mutex); btrfs_run_delayed_iputs(fs_info); - mutex_unlock(&fs_info->cleaner_delayed_iput_mutex); + wait_event(fs_info->delayed_iputs_wait, + atomic_read(&fs_info->nr_delayed_iputs) == 0); trans = btrfs_join_transaction(fs_info->extent_root); if (IS_ERR(trans)) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 3c42d8887183..57bf514a90eb 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -3260,6 +3260,7 @@ void btrfs_add_delayed_iput(struct inode *inode) if (atomic_add_unless(&inode->i_count, -1, 1)) return; + atomic_inc(&fs_info->nr_delayed_iputs); spin_lock(&fs_info->delayed_iput_lock); ASSERT(list_empty(&binode->delayed_iput)); list_add_tail(&binode->delayed_iput, &fs_info->delayed_iputs); @@ -3279,11 +3280,31 @@ void btrfs_run_delayed_iputs(struct btrfs_fs_info *fs_info) list_del_init(&inode->delayed_iput); spin_unlock(&fs_info->delayed_iput_lock); iput(&inode->vfs_inode); + if (atomic_dec_and_test(&fs_info->nr_delayed_iputs)) + wake_up(&fs_info->delayed_iputs_wait); spin_lock(&fs_info->delayed_iput_lock); } spin_unlock(&fs_info->delayed_iput_lock); } +/** + * btrfs_wait_on_delayed_iputs - wait on the delayed iputs to be done running + * @fs_info - the fs_info for this fs + * @return - EINTR if we were killed, 0 if nothing's pending + * + * This will wait on any delayed iputs that are currently running with KILLABLE + * set. Once they are all done running we will return, unless we are killed in + * which case we return EINTR. + */ +int btrfs_wait_on_delayed_iputs(struct btrfs_fs_info *fs_info) +{ + int ret = wait_event_killable(fs_info->delayed_iputs_wait, + atomic_read(&fs_info->nr_delayed_iputs) == 0); + if (ret) + return -EINTR; + return 0; +} + /* * This creates an orphan entry for the given inode in case something goes wrong * in the middle of an unlink.
The throttle path doesn't take cleaner_delayed_iput_mutex, which means we could think we're done flushing iputs in the data space reservation path when we could have a throttler doing an iput. There's no real reason to serialize the delayed iput flushing, so instead of taking the cleaner_delayed_iput_mutex whenever we flush the delayed iputs just replace it with an atomic counter and a waitqueue. This removes the short (or long depending on how big the inode is) window where we think there are no more pending iputs when there really are some. Signed-off-by: Josef Bacik <josef@toxicpanda.com> --- fs/btrfs/ctree.h | 4 +++- fs/btrfs/disk-io.c | 5 ++--- fs/btrfs/extent-tree.c | 9 +++++---- fs/btrfs/inode.c | 21 +++++++++++++++++++++ 4 files changed, 31 insertions(+), 8 deletions(-)