From 8d510121bfbf87302e0594d2022c5e7d52b26f7f Mon Sep 17 00:00:00 2001 From: Nikolay Borisov Date: Tue, 8 Oct 2019 20:43:06 +0300 Subject: btrfs: Rename btrfs_join_transaction_nolock This function is used only during the final phase of freespace cache writeout. This is necessary since using the plain btrfs_join_transaction api is deadlock prone. The deadlock looks like: T1: btrfs_commit_transaction commit_cowonly_roots btrfs_write_dirty_block_groups btrfs_wait_cache_io __btrfs_wait_cache_io btrfs_wait_ordered_range <-- Triggers ordered IO for freespace inode and blocks transaction commit until freespace cache writeout T2: <-- after T1 has triggered the writeout finish_ordered_fn btrfs_finish_ordered_io btrfs_join_transaction <--- this would block waiting for current transaction to commit, but since trans commit is waiting for this writeout to finish The special purpose functions prevents it by simply skipping the "wait for writeout" since it's guaranteed the transaction won't proceed until we are done. Reviewed-by: Qu Wenruo Signed-off-by: Nikolay Borisov Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/inode.c | 12 ++++++------ fs/btrfs/transaction.c | 2 +- fs/btrfs/transaction.h | 2 +- 3 files changed, 8 insertions(+), 8 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 7ed0fe2dd5ba..3315a6eb09a3 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -3066,7 +3066,7 @@ static int btrfs_finish_ordered_io(struct btrfs_ordered_extent *ordered_extent) int compress_type = 0; int ret = 0; u64 logical_len = ordered_extent->len; - bool nolock; + bool freespace_inode; bool truncated = false; bool range_locked = false; bool clear_new_delalloc_bytes = false; @@ -3077,7 +3077,7 @@ static int btrfs_finish_ordered_io(struct btrfs_ordered_extent *ordered_extent) !test_bit(BTRFS_ORDERED_DIRECT, &ordered_extent->flags)) clear_new_delalloc_bytes = true; - nolock = btrfs_is_free_space_inode(BTRFS_I(inode)); + freespace_inode = btrfs_is_free_space_inode(BTRFS_I(inode)); if (test_bit(BTRFS_ORDERED_IOERR, &ordered_extent->flags)) { ret = -EIO; @@ -3108,8 +3108,8 @@ static int btrfs_finish_ordered_io(struct btrfs_ordered_extent *ordered_extent) btrfs_qgroup_free_data(inode, NULL, ordered_extent->file_offset, ordered_extent->len); btrfs_ordered_update_i_size(inode, 0, ordered_extent); - if (nolock) - trans = btrfs_join_transaction_nolock(root); + if (freespace_inode) + trans = btrfs_join_transaction_spacecache(root); else trans = btrfs_join_transaction(root); if (IS_ERR(trans)) { @@ -3143,8 +3143,8 @@ static int btrfs_finish_ordered_io(struct btrfs_ordered_extent *ordered_extent) EXTENT_DEFRAG, 0, 0, &cached_state); } - if (nolock) - trans = btrfs_join_transaction_nolock(root); + if (freespace_inode) + trans = btrfs_join_transaction_spacecache(root); else trans = btrfs_join_transaction(root); if (IS_ERR(trans)) { diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 54b8718054ce..6f133906c862 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -729,7 +729,7 @@ struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root) true); } -struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root) +struct btrfs_trans_handle *btrfs_join_transaction_spacecache(struct btrfs_root *root) { return start_transaction(root, 0, TRANS_JOIN_NOLOCK, BTRFS_RESERVE_NO_FLUSH, true); diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h index 2ac89fb0d709..49f7196368f5 100644 --- a/fs/btrfs/transaction.h +++ b/fs/btrfs/transaction.h @@ -183,7 +183,7 @@ struct btrfs_trans_handle *btrfs_start_transaction_fallback_global_rsv( unsigned int num_items, int min_factor); struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root); -struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root); +struct btrfs_trans_handle *btrfs_join_transaction_spacecache(struct btrfs_root *root); struct btrfs_trans_handle *btrfs_join_transaction_nostart(struct btrfs_root *root); struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root); struct btrfs_trans_handle *btrfs_attach_transaction_barrier( -- cgit v1.2.3