btrfs: remove unnecessary directory inode item update when deleting dir entry
When we remove a directory entry, as part of an unlink operation, if the directory was logged before we must remove the directory index items from the log. We are also updating the inode item of the directory to update its i_size, but that is not necessary because during log replay we do not need it and we correctly adjust the i_size in the inode item of the subvolume as we process directory index items and replay deletes. This is not needed since commit d555438b ("Btrfs: drop dir i_size when adding new names on replay"), where we explicitly ignore the i_size of directory inode items on log replay. Before that we used it but it was buggy as mentioned in that commit's change log (i_size got a larger value then it should have). So stop updating the i_size of the directory inode item in the log, as that is a waste of time, adds more log contention to the log tree and often results in COWing more extent buffers for the log tree. This code path is triggered often during dbench workloads for example. This patch is part of a patchset comprised of the following patches: btrfs: remove unnecessary directory inode item update when deleting dir entry btrfs: stop setting nbytes when filling inode item for logging btrfs: avoid logging new ancestor inodes when logging new inode btrfs: skip logging directories already logged when logging all parents btrfs: skip logging inodes already logged when logging new entries btrfs: remove unnecessary check_parent_dirs_for_sync() btrfs: make concurrent fsyncs wait less when waiting for a transaction commit Performance results, after applying all patches, are mentioned in the change log of the last patch. Reviewed-by:Josef Bacik <josef@toxicpanda.com> Signed-off-by:
Filipe Manana <fdmanana@suse.com> Signed-off-by:
David Sterba <dsterba@suse.com>
parent
42034313
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