| Message ID | 1360599099-30657-1-git-send-email-dsterba@suse.cz (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi David, thank you for addressing this issue. On Mon, Feb 11, 2013 at 6:11 PM, David Sterba <dsterba@suse.cz> wrote: > Each time pick one dead root from the list and let the caller know if > it's needed to continue. This should improve responsiveness during > umount and balance which at some point wait for cleaning all currently > queued dead roots. > > A new dead root is added to the end of the list, so the snapshots > disappear in the order of deletion. > > Process snapshot cleaning is now done only from the cleaner thread and > the others wake it if needed. This is great. > > Signed-off-by: David Sterba <dsterba@suse.cz> > --- > > * btrfs_clean_old_snapshots is removed from the reloc loop, I don't know if this > is safe wrt reloc's assumptions > > * btrfs_run_delayed_iputs is left in place in super_commit, may get removed as > well because transaction commit calls it in the end > > * the responsiveness can be improved further if btrfs_drop_snapshot check > fs_closing, but this needs changes to error handling in the main reloc loop > > fs/btrfs/disk-io.c | 8 ++++-- > fs/btrfs/relocation.c | 3 -- > fs/btrfs/transaction.c | 57 ++++++++++++++++++++++++++++++++---------------- > fs/btrfs/transaction.h | 2 +- > 4 files changed, 44 insertions(+), 26 deletions(-) > > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > index 51bff86..6a02336 100644 > --- a/fs/btrfs/disk-io.c > +++ b/fs/btrfs/disk-io.c > @@ -1635,15 +1635,17 @@ static int cleaner_kthread(void *arg) > struct btrfs_root *root = arg; > > do { > + int again = 0; > + > if (!(root->fs_info->sb->s_flags & MS_RDONLY) && > mutex_trylock(&root->fs_info->cleaner_mutex)) { > btrfs_run_delayed_iputs(root); > - btrfs_clean_old_snapshots(root); > + again = btrfs_clean_one_deleted_snapshot(root); > mutex_unlock(&root->fs_info->cleaner_mutex); > btrfs_run_defrag_inodes(root->fs_info); > } > > - if (!try_to_freeze()) { > + if (!try_to_freeze() && !again) { > set_current_state(TASK_INTERRUPTIBLE); > if (!kthread_should_stop()) > schedule(); > @@ -3301,8 +3303,8 @@ int btrfs_commit_super(struct btrfs_root *root) > > mutex_lock(&root->fs_info->cleaner_mutex); > btrfs_run_delayed_iputs(root); > - btrfs_clean_old_snapshots(root); > mutex_unlock(&root->fs_info->cleaner_mutex); > + wake_up_process(root->fs_info->cleaner_kthread); I am probably missing something, but if the cleaner wakes up here, won't it attempt cleaning the next snap? Because I don't see the cleaner checking anywhere that we are unmounting. Or at this point dead_roots is supposed to be empty? > > /* wait until ongoing cleanup work done */ > down_write(&root->fs_info->cleanup_work_sem); > diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c > index ba5a321..ab6a718 100644 > --- a/fs/btrfs/relocation.c > +++ b/fs/btrfs/relocation.c > @@ -4060,10 +4060,7 @@ int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start) > > while (1) { > mutex_lock(&fs_info->cleaner_mutex); > - > - btrfs_clean_old_snapshots(fs_info->tree_root); > ret = relocate_block_group(rc); > - > mutex_unlock(&fs_info->cleaner_mutex); > if (ret < 0) { > err = ret; > diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c > index 361fb7d..f1e3606 100644 > --- a/fs/btrfs/transaction.c > +++ b/fs/btrfs/transaction.c > @@ -895,7 +895,7 @@ static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans, > int btrfs_add_dead_root(struct btrfs_root *root) > { > spin_lock(&root->fs_info->trans_lock); > - list_add(&root->root_list, &root->fs_info->dead_roots); > + list_add_tail(&root->root_list, &root->fs_info->dead_roots); > spin_unlock(&root->fs_info->trans_lock); > return 0; > } > @@ -1783,31 +1783,50 @@ cleanup_transaction: > } > > /* > - * interface function to delete all the snapshots we have scheduled for deletion > + * return < 0 if error > + * 0 if there are no more dead_roots at the time of call > + * 1 there are more to be processed, call me again > + * > + * The return value indicates there are certainly more snapshots to delete, but > + * if there comes a new one during processing, it may return 0. We don't mind, > + * because btrfs_commit_super will poke cleaner thread and it will process it a > + * few seconds later. > */ > -int btrfs_clean_old_snapshots(struct btrfs_root *root) > +int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root) > { > - LIST_HEAD(list); > + int ret; > + int run_again = 1; > struct btrfs_fs_info *fs_info = root->fs_info; > > + if (root->fs_info->sb->s_flags & MS_RDONLY) { > + pr_debug(G "btrfs: cleaner called for RO fs!\n"); > + return 0; > + } > + > spin_lock(&fs_info->trans_lock); > - list_splice_init(&fs_info->dead_roots, &list); > + if (list_empty(&fs_info->dead_roots)) { > + spin_unlock(&fs_info->trans_lock); > + return 0; > + } > + root = list_first_entry(&fs_info->dead_roots, > + struct btrfs_root, root_list); > + list_del(&root->root_list); > spin_unlock(&fs_info->trans_lock); > > - while (!list_empty(&list)) { > - int ret; > - > - root = list_entry(list.next, struct btrfs_root, root_list); > - list_del(&root->root_list); > + pr_debug("btrfs: cleaner removing %llu\n", > + (unsigned long long)root->objectid); > > - btrfs_kill_all_delayed_nodes(root); > + btrfs_kill_all_delayed_nodes(root); > > - if (btrfs_header_backref_rev(root->node) < > - BTRFS_MIXED_BACKREF_REV) > - ret = btrfs_drop_snapshot(root, NULL, 0, 0); > - else > - ret =btrfs_drop_snapshot(root, NULL, 1, 0); > - BUG_ON(ret < 0); > - } > - return 0; > + if (btrfs_header_backref_rev(root->node) < > + BTRFS_MIXED_BACKREF_REV) > + ret = btrfs_drop_snapshot(root, NULL, 0, 0); > + else > + ret = btrfs_drop_snapshot(root, NULL, 1, 0); > + /* > + * If we encounter a transaction abort during snapshot cleaning, we > + * don't want to crash here > + */ > + BUG_ON(ret < 0 && (ret != -EAGAIN || ret != -EROFS)); > + return run_again || ret == -EAGAIN; Can you tell me when btrfs_drop_snapshot is supposed to return EAGAIN? > } > diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h > index 69700f7..f8e9583 100644 > --- a/fs/btrfs/transaction.h > +++ b/fs/btrfs/transaction.h > @@ -118,7 +118,7 @@ int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans, > > int btrfs_add_dead_root(struct btrfs_root *root); > int btrfs_defrag_root(struct btrfs_root *root, int cacheonly); > -int btrfs_clean_old_snapshots(struct btrfs_root *root); > +int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root); > int btrfs_commit_transaction(struct btrfs_trans_handle *trans, > struct btrfs_root *root); > int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans, > -- > 1.7.9 > Thanks, Alex. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 51bff86..6a02336 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1635,15 +1635,17 @@ static int cleaner_kthread(void *arg) struct btrfs_root *root = arg; do { + int again = 0; + if (!(root->fs_info->sb->s_flags & MS_RDONLY) && mutex_trylock(&root->fs_info->cleaner_mutex)) { btrfs_run_delayed_iputs(root); - btrfs_clean_old_snapshots(root); + again = btrfs_clean_one_deleted_snapshot(root); mutex_unlock(&root->fs_info->cleaner_mutex); btrfs_run_defrag_inodes(root->fs_info); } - if (!try_to_freeze()) { + if (!try_to_freeze() && !again) { set_current_state(TASK_INTERRUPTIBLE); if (!kthread_should_stop()) schedule(); @@ -3301,8 +3303,8 @@ int btrfs_commit_super(struct btrfs_root *root) mutex_lock(&root->fs_info->cleaner_mutex); btrfs_run_delayed_iputs(root); - btrfs_clean_old_snapshots(root); mutex_unlock(&root->fs_info->cleaner_mutex); + wake_up_process(root->fs_info->cleaner_kthread); /* wait until ongoing cleanup work done */ down_write(&root->fs_info->cleanup_work_sem); diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index ba5a321..ab6a718 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -4060,10 +4060,7 @@ int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start) while (1) { mutex_lock(&fs_info->cleaner_mutex); - - btrfs_clean_old_snapshots(fs_info->tree_root); ret = relocate_block_group(rc); - mutex_unlock(&fs_info->cleaner_mutex); if (ret < 0) { err = ret; diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 361fb7d..f1e3606 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -895,7 +895,7 @@ static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans, int btrfs_add_dead_root(struct btrfs_root *root) { spin_lock(&root->fs_info->trans_lock); - list_add(&root->root_list, &root->fs_info->dead_roots); + list_add_tail(&root->root_list, &root->fs_info->dead_roots); spin_unlock(&root->fs_info->trans_lock); return 0; } @@ -1783,31 +1783,50 @@ cleanup_transaction: } /* - * interface function to delete all the snapshots we have scheduled for deletion + * return < 0 if error + * 0 if there are no more dead_roots at the time of call + * 1 there are more to be processed, call me again + * + * The return value indicates there are certainly more snapshots to delete, but + * if there comes a new one during processing, it may return 0. We don't mind, + * because btrfs_commit_super will poke cleaner thread and it will process it a + * few seconds later. */ -int btrfs_clean_old_snapshots(struct btrfs_root *root) +int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root) { - LIST_HEAD(list); + int ret; + int run_again = 1; struct btrfs_fs_info *fs_info = root->fs_info; + if (root->fs_info->sb->s_flags & MS_RDONLY) { + pr_debug(G "btrfs: cleaner called for RO fs!\n"); + return 0; + } + spin_lock(&fs_info->trans_lock); - list_splice_init(&fs_info->dead_roots, &list); + if (list_empty(&fs_info->dead_roots)) { + spin_unlock(&fs_info->trans_lock); + return 0; + } + root = list_first_entry(&fs_info->dead_roots, + struct btrfs_root, root_list); + list_del(&root->root_list); spin_unlock(&fs_info->trans_lock); - while (!list_empty(&list)) { - int ret; - - root = list_entry(list.next, struct btrfs_root, root_list); - list_del(&root->root_list); + pr_debug("btrfs: cleaner removing %llu\n", + (unsigned long long)root->objectid); - btrfs_kill_all_delayed_nodes(root); + btrfs_kill_all_delayed_nodes(root); - if (btrfs_header_backref_rev(root->node) < - BTRFS_MIXED_BACKREF_REV) - ret = btrfs_drop_snapshot(root, NULL, 0, 0); - else - ret =btrfs_drop_snapshot(root, NULL, 1, 0); - BUG_ON(ret < 0); - } - return 0; + if (btrfs_header_backref_rev(root->node) < + BTRFS_MIXED_BACKREF_REV) + ret = btrfs_drop_snapshot(root, NULL, 0, 0); + else + ret = btrfs_drop_snapshot(root, NULL, 1, 0); + /* + * If we encounter a transaction abort during snapshot cleaning, we + * don't want to crash here + */ + BUG_ON(ret < 0 && (ret != -EAGAIN || ret != -EROFS)); + return run_again || ret == -EAGAIN; } diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h index 69700f7..f8e9583 100644 --- a/fs/btrfs/transaction.h +++ b/fs/btrfs/transaction.h @@ -118,7 +118,7 @@ int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans, int btrfs_add_dead_root(struct btrfs_root *root); int btrfs_defrag_root(struct btrfs_root *root, int cacheonly); -int btrfs_clean_old_snapshots(struct btrfs_root *root); +int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root); int btrfs_commit_transaction(struct btrfs_trans_handle *trans, struct btrfs_root *root); int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
Each time pick one dead root from the list and let the caller know if it's needed to continue. This should improve responsiveness during umount and balance which at some point wait for cleaning all currently queued dead roots. A new dead root is added to the end of the list, so the snapshots disappear in the order of deletion. Process snapshot cleaning is now done only from the cleaner thread and the others wake it if needed. Signed-off-by: David Sterba <dsterba@suse.cz> --- * btrfs_clean_old_snapshots is removed from the reloc loop, I don't know if this is safe wrt reloc's assumptions * btrfs_run_delayed_iputs is left in place in super_commit, may get removed as well because transaction commit calls it in the end * the responsiveness can be improved further if btrfs_drop_snapshot check fs_closing, but this needs changes to error handling in the main reloc loop fs/btrfs/disk-io.c | 8 ++++-- fs/btrfs/relocation.c | 3 -- fs/btrfs/transaction.c | 57 ++++++++++++++++++++++++++++++++---------------- fs/btrfs/transaction.h | 2 +- 4 files changed, 44 insertions(+), 26 deletions(-)