On Mon, May 09, 2022 at 10:41:27AM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> The operations performed from XFS_DAS_FOUND_LBLK through to
> XFS_DAS_RM_LBLK are now identical to XFS_DAS_FOUND_NBLK through to
> XFS_DAS_RM_NBLK. We can collapse these down into a single set of
> code.
>
> To do this, define the states that leaf and node run through as
> separate sets of sequential states. Then as we move to the next
> state, we can use increments rather than specific state assignments
> to move through the states. This means the state progression is set
> by the initial state that enters the series and we don't need to
> duplicate the code anymore.
>
> At the exit point of the series we need to select the correct leaf
> or node state, but that can also be done by state increment rather
> than assignment.
>
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> Reviewed-by: Allison Henderson<allison.henderson@xxxxxxxxxx>
> ---
> fs/xfs/libxfs/xfs_attr.c | 127 ++++++---------------------------------
> fs/xfs/libxfs/xfs_attr.h | 9 ++-
> 2 files changed, 27 insertions(+), 109 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index ab8a884af512..be580da62f08 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
> @@ -394,6 +394,7 @@ xfs_attr_set_iter(
> struct xfs_mount *mp = args->dp->i_mount;
>
> /* State machine switch */
> +next_state:
> switch (attr->xattri_dela_state) {
> case XFS_DAS_UNINIT:
> ASSERT(0);
> @@ -406,6 +407,7 @@ xfs_attr_set_iter(
> return xfs_attr_node_addname(attr);
>
> case XFS_DAS_FOUND_LBLK:
> + case XFS_DAS_FOUND_NBLK:
> /*
> * Find space for remote blocks and fall into the allocation
> * state.
> @@ -415,9 +417,10 @@ xfs_attr_set_iter(
> if (error)
> return error;
> }
> - attr->xattri_dela_state = XFS_DAS_LEAF_ALLOC_RMT;
> + attr->xattri_dela_state++;
> fallthrough;
> case XFS_DAS_LEAF_ALLOC_RMT:
> + case XFS_DAS_NODE_ALLOC_RMT:
>
> /*
> * If there was an out-of-line value, allocate the blocks we
> @@ -466,16 +469,18 @@ xfs_attr_set_iter(
> return error;
> /*
> * Commit the flag value change and start the next trans
> - * in series.
> + * in series at FLIP_FLAG.
> */
> - attr->xattri_dela_state = XFS_DAS_FLIP_LFLAG;
> + attr->xattri_dela_state++;
> trace_xfs_attr_set_iter_return(attr->xattri_dela_state,
> args->dp);
> return -EAGAIN;
> }
>
> + attr->xattri_dela_state++;
> fallthrough;
> case XFS_DAS_FLIP_LFLAG:
> + case XFS_DAS_FLIP_NFLAG:
> /*
> * Dismantle the "old" attribute/value pair by removing a
> * "remote" value (if it exists).
> @@ -485,10 +490,10 @@ xfs_attr_set_iter(
> if (error)
> return error;
>
> + attr->xattri_dela_state++;
> fallthrough;
> case XFS_DAS_RM_LBLK:
> - /* Set state in case xfs_attr_rmtval_remove returns -EAGAIN */
> - attr->xattri_dela_state = XFS_DAS_RM_LBLK;
> + case XFS_DAS_RM_NBLK:
> if (args->rmtblkno) {
> error = xfs_attr_rmtval_remove(attr);
> if (error == -EAGAIN)
> @@ -503,7 +508,16 @@ xfs_attr_set_iter(
> return -EAGAIN;
> }
>
> - fallthrough;
> + /*
> + * This is the end of the shared leaf/node sequence. We need
> + * to continue at the next state in the sequence, but we can't
> + * easily just fall through. So we increment to the next state
> + * and then jump back to switch statement to evaluate the next
> + * state correctly.
> + */
> + attr->xattri_dela_state++;
> + goto next_state;
> +
> case XFS_DAS_RD_LEAF:
> /*
> * This is the last step for leaf format. Read the block with
> @@ -524,106 +538,6 @@ xfs_attr_set_iter(
>
> return error;
>
> - case XFS_DAS_FOUND_NBLK:
> - /*
> - * Find space for remote blocks and fall into the allocation
> - * state.
> - */
> - if (args->rmtblkno > 0) {
> - error = xfs_attr_rmtval_find_space(attr);
> - if (error)
> - return error;
> - }
> -
> - attr->xattri_dela_state = XFS_DAS_NODE_ALLOC_RMT;
> - fallthrough;
> - case XFS_DAS_NODE_ALLOC_RMT:
> - /*
> - * If there was an out-of-line value, allocate the blocks we
> - * identified for its storage and copy the value. This is done
> - * after we create the attribute so that we don't overflow the
> - * maximum size of a transaction and/or hit a deadlock.
> - */
> - if (args->rmtblkno > 0) {
> - if (attr->xattri_blkcnt > 0) {
> - error = xfs_attr_rmtval_set_blk(attr);
> - if (error)
> - return error;
> - trace_xfs_attr_set_iter_return(
> - attr->xattri_dela_state, args->dp);
> - return -EAGAIN;
> - }
> -
> - error = xfs_attr_rmtval_set_value(args);
> - if (error)
> - return error;
> - }
> -
> - /*
> - * If this was not a rename, clear the incomplete flag and we're
> - * done.
> - */
> - if (!(args->op_flags & XFS_DA_OP_RENAME)) {
> - if (args->rmtblkno > 0)
> - error = xfs_attr3_leaf_clearflag(args);
> - goto out;
> - }
> -
> - /*
> - * If this is an atomic rename operation, we must "flip" the
> - * incomplete flags on the "new" and "old" attribute/value pairs
> - * so that one disappears and one appears atomically. Then we
> - * must remove the "old" attribute/value pair.
> - *
> - * In a separate transaction, set the incomplete flag on the
> - * "old" attr and clear the incomplete flag on the "new" attr.
> - */
> - if (!xfs_has_larp(mp)) {
> - error = xfs_attr3_leaf_flipflags(args);
> - if (error)
> - goto out;
> - /*
> - * Commit the flag value change and start the next trans
> - * in series
> - */
> - attr->xattri_dela_state = XFS_DAS_FLIP_NFLAG;
> - trace_xfs_attr_set_iter_return(attr->xattri_dela_state,
> - args->dp);
> - return -EAGAIN;
> - }
> -
> - fallthrough;
> - case XFS_DAS_FLIP_NFLAG:
> - /*
> - * Dismantle the "old" attribute/value pair by removing a
> - * "remote" value (if it exists).
> - */
> - xfs_attr_restore_rmt_blk(args);
> -
> - error = xfs_attr_rmtval_invalidate(args);
> - if (error)
> - return error;
> -
> - fallthrough;
> - case XFS_DAS_RM_NBLK:
> - /* Set state in case xfs_attr_rmtval_remove returns -EAGAIN */
> - attr->xattri_dela_state = XFS_DAS_RM_NBLK;
> - if (args->rmtblkno) {
> - error = xfs_attr_rmtval_remove(attr);
> - if (error == -EAGAIN)
> - trace_xfs_attr_set_iter_return(
> - attr->xattri_dela_state, args->dp);
> -
> - if (error)
> - return error;
> -
> - attr->xattri_dela_state = XFS_DAS_CLR_FLAG;
> - trace_xfs_attr_set_iter_return(attr->xattri_dela_state,
> - args->dp);
> - return -EAGAIN;
> - }
> -
> - fallthrough;
> case XFS_DAS_CLR_FLAG:
> /*
> * The last state for node format. Look up the old attr and
> @@ -635,7 +549,6 @@ xfs_attr_set_iter(
> ASSERT(0);
> break;
> }
> -out:
> return error;
> }
>
> diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
> index d016af4dbf81..37db61649217 100644
> --- a/fs/xfs/libxfs/xfs_attr.h
> +++ b/fs/xfs/libxfs/xfs_attr.h
> @@ -450,16 +450,21 @@ enum xfs_delattr_state {
> XFS_DAS_RMTBLK, /* Removing remote blks */
> XFS_DAS_RM_NAME, /* Remove attr name */
> XFS_DAS_RM_SHRINK, /* We are shrinking the tree */
> +
> + /* Leaf state set sequence */
I think this comment should note that the state increment operations of
xfs_attr_set_iter requires that the exact order of the values
FOUND_[LN]BLK through RM_[LN]BLK must be preserved exactly.
Question: Are we supposed to be able to dela_state++ our way from
RM_LBLK to RD_LEAF and from RM_NBLK to CLR_FLAG?
With that comment added,
Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
--D
> XFS_DAS_FOUND_LBLK, /* We found leaf blk for attr */
> XFS_DAS_LEAF_ALLOC_RMT, /* We are allocating remote blocks */
> - XFS_DAS_FOUND_NBLK, /* We found node blk for attr */
> - XFS_DAS_NODE_ALLOC_RMT, /* We are allocating remote blocks */
> XFS_DAS_FLIP_LFLAG, /* Flipped leaf INCOMPLETE attr flag */
> XFS_DAS_RM_LBLK, /* A rename is removing leaf blocks */
> XFS_DAS_RD_LEAF, /* Read in the new leaf */
> +
> + /* Node state set sequence, must match leaf state above */
> + XFS_DAS_FOUND_NBLK, /* We found node blk for attr */
> + XFS_DAS_NODE_ALLOC_RMT, /* We are allocating remote blocks */
> XFS_DAS_FLIP_NFLAG, /* Flipped node INCOMPLETE attr flag */
> XFS_DAS_RM_NBLK, /* A rename is removing node blocks */
> XFS_DAS_CLR_FLAG, /* Clear incomplete flag */
> +
> XFS_DAS_DONE, /* finished operation */
> };
>
> --
> 2.35.1
>
