On Thu, Feb 18, 2021 at 09:53:43AM -0700, Allison Henderson wrote:
> This is a clean up patch that skips the flip flag logic for delayed attr
> renames. Since the log replay keeps the inode locked, we do not need to
> worry about race windows with attr lookups. So we can skip over
> flipping the flag and the extra transaction roll for it
>
> Signed-off-by: Allison Henderson <allison.henderson@xxxxxxxxxx>
I wonder, have you done much performance analysis of the old vs. new
xattr code paths? Does skipping the extra step + roll make attr
operations faster?
This looks pretty straightforward though:
Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
--D
> ---
> fs/xfs/libxfs/xfs_attr.c | 51 +++++++++++++++++++++++++------------------
> fs/xfs/libxfs/xfs_attr_leaf.c | 3 ++-
> 2 files changed, 32 insertions(+), 22 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index e4c1b4b..666cc69 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
> @@ -337,6 +337,7 @@ xfs_attr_set_iter(
> struct xfs_da_state *state = NULL;
> int forkoff, error = 0;
> int retval = 0;
> + struct xfs_mount *mp = args->dp->i_mount;
>
> /* State machine switch */
> switch (dac->dela_state) {
> @@ -470,16 +471,21 @@ xfs_attr_set_iter(
> * "old" attr and clear the incomplete flag on the "new" attr.
> */
>
> - error = xfs_attr3_leaf_flipflags(args);
> - if (error)
> - return error;
> - /*
> - * Commit the flag value change and start the next trans in
> - * series.
> - */
> - dac->dela_state = XFS_DAS_FLIP_LFLAG;
> - trace_xfs_attr_set_iter_return(dac->dela_state, args->dp);
> - return -EAGAIN;
> + if (!xfs_hasdelattr(mp)) {
> + error = xfs_attr3_leaf_flipflags(args);
> + if (error)
> + return error;
> + /*
> + * Commit the flag value change and start the next trans
> + * in series.
> + */
> + dac->dela_state = XFS_DAS_FLIP_LFLAG;
> + trace_xfs_attr_set_iter_return(dac->dela_state,
> + args->dp);
> + return -EAGAIN;
> + }
> +
> + /* fallthrough */
> case XFS_DAS_FLIP_LFLAG:
> /*
> * Dismantle the "old" attribute/value pair by removing a
> @@ -588,17 +594,21 @@ xfs_attr_set_iter(
> * In a separate transaction, set the incomplete flag on the
> * "old" attr and clear the incomplete flag on the "new" attr.
> */
> - error = xfs_attr3_leaf_flipflags(args);
> - if (error)
> - goto out;
> - /*
> - * Commit the flag value change and start the next trans in
> - * series
> - */
> - dac->dela_state = XFS_DAS_FLIP_NFLAG;
> - trace_xfs_attr_set_iter_return(dac->dela_state, args->dp);
> - return -EAGAIN;
> + if (!xfs_hasdelattr(mp)) {
> + error = xfs_attr3_leaf_flipflags(args);
> + if (error)
> + goto out;
> + /*
> + * Commit the flag value change and start the next trans
> + * in series
> + */
> + dac->dela_state = XFS_DAS_FLIP_NFLAG;
> + trace_xfs_attr_set_iter_return(dac->dela_state,
> + args->dp);
> + return -EAGAIN;
> + }
>
> + /* fallthrough */
> case XFS_DAS_FLIP_NFLAG:
> /*
> * Dismantle the "old" attribute/value pair by removing a
> @@ -1277,7 +1287,6 @@ int xfs_attr_node_addname_work(
> * Re-find the "old" attribute entry after any split ops. The INCOMPLETE
> * flag means that we will find the "old" attr, not the "new" one.
> */
> - args->attr_filter |= XFS_ATTR_INCOMPLETE;
> state = xfs_da_state_alloc(args);
> state->inleaf = 0;
> error = xfs_da3_node_lookup_int(state, &retval);
> diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
> index 3780141..ec707bd 100644
> --- a/fs/xfs/libxfs/xfs_attr_leaf.c
> +++ b/fs/xfs/libxfs/xfs_attr_leaf.c
> @@ -1486,7 +1486,8 @@ xfs_attr3_leaf_add_work(
> if (tmp)
> entry->flags |= XFS_ATTR_LOCAL;
> if (args->op_flags & XFS_DA_OP_RENAME) {
> - entry->flags |= XFS_ATTR_INCOMPLETE;
> + if (!xfs_hasdelattr(mp))
> + entry->flags |= XFS_ATTR_INCOMPLETE;
> if ((args->blkno2 == args->blkno) &&
> (args->index2 <= args->index)) {
> args->index2++;
> --
> 2.7.4
>
