From: Nikolay Borisov Date: Thu, 23 May 2019 11:51:26 +0000 (+0300) Subject: btrfs: Remove unnecessary check from join_running_log_trans X-Git-Tag: v5.4-rc1~123^2~112 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=e678934cbe5f026c2765a1da651e61daa5724fb3;p=linux.git btrfs: Remove unnecessary check from join_running_log_trans join_running_log_trans checks btrfs_root::log_root outside of btrfs_root::log_mutex to avoid contention on the mutex. Turns out this check is not necessary because the two callers of join_running_log_trans (both of which deal with removing entries from the tree-log during unlink) explicitly check whether the respective inode has been logged in the current transaction. If it hasn't then it won't have any items in the tree-log and call path will return before calling join_running_log_trans. If the check passes, however, then it's guaranteed that btrfs_root::log_root is set because the inode is logged. Those guarantees allows us to remove the speculative as well as the implicity and tricky memory barrier. Reviewed-by: Filipe Manana Signed-off-by: Nikolay Borisov Signed-off-by: David Sterba --- diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 6c8297bcfeb7..188e6f79ab4e 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -188,10 +188,6 @@ static int join_running_log_trans(struct btrfs_root *root) { int ret = -ENOENT; - smp_mb(); - if (!root->log_root) - return -ENOENT; - mutex_lock(&root->log_mutex); if (root->log_root) { ret = 0;