From 4934a8150214c39433b9ea7975ccfaeb24f6812c Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Tue, 31 Aug 2021 15:30:37 +0100 Subject: [PATCH] btrfs: avoid expensive search when truncating inode items from the log Whenever we are logging a file inode in full sync mode we call btrfs_truncate_inode_items() to delete items of the inode we may have previously logged. That results in doing a btree search for deletion, which is expensive because it always acquires write locks for extent buffers at levels 2, 1 and 0, and it balances any node that is less than half full. Acquiring the write locks can block the task if the extent buffers are already locked by another task or block other tasks attempting to lock them, which is specially bad in case of log trees since they are small due to their short life, with a root node at a level typically not greater than level 2. If we know that we are logging the inode for the first time in the current transaction, we can skip the call to btrfs_truncate_inode_items(), avoiding the deletion search. This change does that. This patch is part of a patch set comprised of the following patches: btrfs: check if a log tree exists at inode_logged() btrfs: remove no longer needed checks for NULL log context btrfs: do not log new dentries when logging that a new name exists btrfs: always update the logged transaction when logging new names btrfs: avoid expensive search when dropping inode items from log btrfs: add helper to truncate inode items when logging inode btrfs: avoid expensive search when truncating inode items from the log btrfs: avoid search for logged i_size when logging inode if possible btrfs: avoid attempt to drop extents when logging inode for the first time btrfs: do not commit delayed inode when logging a file in full sync mode This is patch 7/10 and test results are listed in the change log of the last patch in the set. Signed-off-by: Filipe Manana Signed-off-by: David Sterba --- fs/btrfs/tree-log.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 2d92187a12737..94964e62e430e 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -5488,7 +5488,9 @@ static int btrfs_log_inode(struct btrfs_trans_handle *trans, &inode->runtime_flags); clear_bit(BTRFS_INODE_COPY_EVERYTHING, &inode->runtime_flags); - ret = truncate_inode_items(trans, log, inode, 0, 0); + if (inode_logged(trans, inode)) + ret = truncate_inode_items(trans, log, + inode, 0, 0); } } else if (test_and_clear_bit(BTRFS_INODE_COPY_EVERYTHING, &inode->runtime_flags) || -- 2.39.5