Re: [PATCH v13 03/10] xfs: Add delay ready attr set routines

Darrick J. Wong
2020-11-10T23:10:29Z

On Thu, Oct 22, 2020 at 11:34:28PM -0700, Allison Henderson wrote:
> This patch modifies the attr set routines to be delay ready. This means
> they no longer roll or commit transactions, but instead return -EAGAIN
> to have the calling routine roll and refresh the transaction. In this
> series, xfs_attr_set_args has become xfs_attr_set_iter, which uses a
> state machine like switch to keep track of where it was when EAGAIN was
> returned. See xfs_attr.h for a more detailed diagram of the states.
>
> Two new helper functions have been added: xfs_attr_rmtval_set_init and
> xfs_attr_rmtval_set_blk. They provide a subset of logic similar to
> xfs_attr_rmtval_set, but they store the current block in the delay attr
> context to allow the caller to roll the transaction between allocations.
> This helps to simplify and consolidate code used by
> xfs_attr_leaf_addname and xfs_attr_node_addname. xfs_attr_set_args has
> now become a simple loop to refresh the transaction until the operation
> is completed. Lastly, xfs_attr_rmtval_remove is no longer used, and is
> removed.
>
> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> ---
> fs/xfs/libxfs/xfs_attr.c | 370 ++++++++++++++++++++++++++--------------
> fs/xfs/libxfs/xfs_attr.h | 126 +++++++++++++-
> fs/xfs/libxfs/xfs_attr_remote.c | 99 +++++++----
> fs/xfs/libxfs/xfs_attr_remote.h | 4 +
> fs/xfs/xfs_trace.h | 1 -
> 5 files changed, 439 insertions(+), 161 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index 6ca94cb..95c98d7 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
> @@ -44,7 +44,7 @@ STATIC int xfs_attr_shortform_addname(xfs_da_args_t *args);
> * Internal routines when attribute list is one block.
> */
> STATIC int xfs_attr_leaf_get(xfs_da_args_t *args);
> -STATIC int xfs_attr_leaf_addname(xfs_da_args_t *args);
> +STATIC int xfs_attr_leaf_addname(struct xfs_delattr_context *dac);
> STATIC int xfs_attr_leaf_removename(xfs_da_args_t *args);
> STATIC int xfs_attr_leaf_hasname(struct xfs_da_args *args, struct xfs_buf **bp);
>
> @@ -52,12 +52,15 @@ STATIC int xfs_attr_leaf_hasname(struct xfs_da_args *args, struct xfs_buf **bp);
> * Internal routines when attribute list is more than one block.
> */
> STATIC int xfs_attr_node_get(xfs_da_args_t *args);
> -STATIC int xfs_attr_node_addname(xfs_da_args_t *args);
> +STATIC int xfs_attr_node_addname(struct xfs_delattr_context *dac);
> STATIC int xfs_attr_node_removename_iter(struct xfs_delattr_context *dac);
> STATIC int xfs_attr_node_hasname(xfs_da_args_t *args,
> struct xfs_da_state **state);
> STATIC int xfs_attr_fillstate(xfs_da_state_t *state);
> STATIC int xfs_attr_refillstate(xfs_da_state_t *state);
> +STATIC int xfs_attr_leaf_try_add(struct xfs_da_args *args, struct xfs_buf *bp);
> +STATIC int xfs_attr_set_iter(struct xfs_delattr_context *dac,
> + struct xfs_buf **leaf_bp);
>
> int
> xfs_inode_hasattr(
> @@ -218,8 +221,11 @@ xfs_attr_is_shortform(
>
> /*
> * Attempts to set an attr in shortform, or converts short form to leaf form if
> - * there is not enough room. If the attr is set, the transaction is committed
> - * and set to NULL.
> + * there is not enough room. This function is meant to operate as a helper
> + * routine to the delayed attribute functions. It returns -EAGAIN to indicate
> + * that the calling function should roll the transaction, and then proceed to
> + * add the attr in leaf form. This subroutine does not expect to be recalled
> + * again like the other delayed attr routines do.
> */
> STATIC int
> xfs_attr_set_shortform(
> @@ -227,16 +233,16 @@ xfs_attr_set_shortform(
> struct xfs_buf **leaf_bp)
> {
> struct xfs_inode *dp = args->dp;
> - int error, error2 = 0;
> + int error = 0;
>
> /*
> * Try to add the attr to the attribute list in the inode.
> */
> error = xfs_attr_try_sf_addname(dp, args);
> +
> + /* Should only be 0, -EEXIST or ENOSPC */

Nit: "...or -ENOSPC"

Also, this comment could go a couple of lines up:

/*
* Try to add the attr to the attribute list in the inode.
* This should only return 0, -EEXIST, or -ENOSPC.
*/
error = xfs_attr_try_sf_addname(dp, args);
if (error != -ENOSPC)
return error;

> if (error != -ENOSPC) {
> - error2 = xfs_trans_commit(args->trans);
> - args->trans = NULL;
> - return error ? error : error2;
> + return error;
> }
> /*
> * It won't fit in the shortform, transform to a leaf block. GROT:
> @@ -249,18 +255,10 @@ xfs_attr_set_shortform(
> /*
> * Prevent the leaf buffer from being unlocked so that a concurrent AIL
> * push cannot grab the half-baked leaf buffer and run into problems
> - * with the write verifier. Once we're done rolling the transaction we
> - * can release the hold and add the attr to the leaf.
> + * with the write verifier.
> */
> xfs_trans_bhold(args->trans, *leaf_bp);
> - error = xfs_defer_finish(&args->trans);
> - xfs_trans_bhold_release(args->trans, *leaf_bp);
> - if (error) {
> - xfs_trans_brelse(args->trans, *leaf_bp);
> - return error;
> - }
> -
> - return 0;
> + return -EAGAIN;

What state are we in when return -EAGAIN here? Are we still in
XFS_DAS_UNINIT, but with an attr fork that is no longer in local format,
which means that we skip the xfs_attr_is_shortform branch next time
around?

> }
>
> /*
> @@ -268,7 +266,7 @@ xfs_attr_set_shortform(
> * also checks for a defer finish. Transaction is finished and rolled as
> * needed, and returns true of false if the delayed operation should continue.
> */
> -int
> +STATIC int
> xfs_attr_trans_roll(
> struct xfs_delattr_context *dac)
> {
> @@ -297,61 +295,130 @@ int
> xfs_attr_set_args(
> struct xfs_da_args *args)
> {
> - struct xfs_inode *dp = args->dp;
> - struct xfs_buf *leaf_bp = NULL;
> - int error = 0;
> + struct xfs_buf *leaf_bp = NULL;
> + int error = 0;
> + struct xfs_delattr_context dac = {
> + .da_args = args,
> + };
> +
> + do {
> + error = xfs_attr_set_iter(&dac, &leaf_bp);
> + if (error != -EAGAIN)
> + break;
> +
> + error = xfs_attr_trans_roll(&dac);
> + if (error)
> + return error;
> +
> + if (leaf_bp) {
> + xfs_trans_bjoin(args->trans, leaf_bp);
> + xfs_trans_bhold(args->trans, leaf_bp);
> + }
> +
> + } while (true);
> +
> + return error;
> +}
> +
> +/*
> + * Set the attribute specified in @args.
> + * This routine is meant to function as a delayed operation, and may return
> + * -EAGAIN when the transaction needs to be rolled. Calling functions will need
> + * to handle this, and recall the function until a successful error code is
> + * returned.
> + */
> +STATIC int
> +xfs_attr_set_iter(
> + struct xfs_delattr_context *dac,
> + struct xfs_buf **leaf_bp)
> +{
> + struct xfs_da_args *args = dac->da_args;
> + struct xfs_inode *dp = args->dp;
> + int error = 0;
> +
> + /* State machine switch */
> + switch (dac->dela_state) {
> + case XFS_DAS_FLIP_LFLAG:
> + case XFS_DAS_FOUND_LBLK:

Do we need to catch XFS_DAS_RM_LBLK here?

> + goto das_leaf;
> + case XFS_DAS_FOUND_NBLK:
> + case XFS_DAS_FLIP_NFLAG:
> + case XFS_DAS_ALLOC_NODE:
> + goto das_node;
> + default:
> + break;
> + }
>
> /*
> * If the attribute list is already in leaf format, jump straight to
> * leaf handling. Otherwise, try to add the attribute to the shortform
> * list; if there's no room then convert the list to leaf format and try
> - * again.
> + * again. No need to set state as we will be in leaf form when we come
> + * back
> */
> if (xfs_attr_is_shortform(dp)) {
>
> /*
> - * If the attr was successfully set in shortform, the
> - * transaction is committed and set to NULL. Otherwise, is it
> - * converted from shortform to leaf, and the transaction is
> - * retained.
> + * If the attr was successfully set in shortform, no need to
> + * continue. Otherwise, is it converted from shortform to leaf
> + * and -EAGAIN is returned.
> */
> - error = xfs_attr_set_shortform(args, &leaf_bp);
> - if (error || !args->trans)
> - return error;
> + error = xfs_attr_set_shortform(args, leaf_bp);
> + if (error == -EAGAIN)
> + dac->flags |= XFS_DAC_DEFER_FINISH;
> +
> + return error;
> }
>
> - if (xfs_bmap_one_block(dp, XFS_ATTR_FORK)) {
> - error = xfs_attr_leaf_addname(args);
> - if (error != -ENOSPC)
> - return error;
> + /*
> + * After a shortform to leaf conversion, we need to hold the leaf and
> + * cycle out the transaction. When we get back, we need to release
> + * the leaf.

"...to release the hold on the leaf buffer."

> + */
> + if (*leaf_bp != NULL) {
> + xfs_trans_bhold_release(args->trans, *leaf_bp);
> + *leaf_bp = NULL;
> + }
>
> - /*
> - * Promote the attribute list to the Btree format.
> - */
> - error = xfs_attr3_leaf_to_node(args);
> - if (error)
> - return error;
> + if (xfs_bmap_one_block(dp, XFS_ATTR_FORK)) {
> + error = xfs_attr_leaf_try_add(args, *leaf_bp);
> + switch (error) {
> + case -ENOSPC:
> + /*
> + * Promote the attribute list to the Btree format.
> + */
> + error = xfs_attr3_leaf_to_node(args);
> + if (error)
> + return error;
>
> - /*
> - * Finish any deferred work items and roll the transaction once
> - * more. The goal here is to call node_addname with the inode
> - * and transaction in the same state (inode locked and joined,
> - * transaction clean) no matter how we got to this step.
> - */
> - error = xfs_defer_finish(&args->trans);
> - if (error)
> + /*
> + * Finish any deferred work items and roll the
> + * transaction once more. The goal here is to call
> + * node_addname with the inode and transaction in the
> + * same state (inode locked and joined, transaction
> + * clean) no matter how we got to this step.
> + */
> + dac->flags |= XFS_DAC_DEFER_FINISH;
> + return -EAGAIN;

What state should we be in at this -EAGAIN return? Is it
XFS_DAS_UNINIT, but with more than one extent in the attr fork?

/me is wishing these would get turned into explicit states, since afaict
we don't unlock the inode and so we should find it in /exactly/ the
state that the delattr_context says it should be in.

> + case 0:
> + dac->dela_state = XFS_DAS_FOUND_LBLK;
> + return -EAGAIN;
> + default:
> return error;
> + }
> +das_leaf:

The only way to get to this block of code is by jumping to das_leaf,
from the switch statement above, right? If so, then shouldn't it be up
there in the switch statement?

> + error = xfs_attr_leaf_addname(dac);
> + if (error == -ENOSPC)
> + /*
> + * No need to set state. We will be in node form when
> + * we are recalled
> + */
> + return -EAGAIN;

How do we get to node form?

> - /*
> - * Commit the current trans (including the inode) and
> - * start a new one.
> - */
> - error = xfs_trans_roll_inode(&args->trans, dp);
> - if (error)
> - return error;
> + return error;
> }
> -
> - error = xfs_attr_node_addname(args);
> +das_node:
> + error = xfs_attr_node_addname(dac);
> return error;

Similarly, I think the only way get to this block of code is if we're in
the initial state (XFS_DAS_UNINIT?) and the inode wasn't in short
format; or if we jumped here via DAS_{FOUND_NBLK,FLIP_NFLAG,ALLOC_NODE},
right?

I think you could straighten this out a bit further (I left out the
comments):

switch (dac->dela_state) {
case XFS_DAS_FLIP_LFLAG:
case XFS_DAS_FOUND_LBLK:
error = xfs_attr_leaf_addname(dac);
if (error == -ENOSPC)
return -EAGAIN;
return error;
case XFS_DAS_FOUND_NBLK:
case XFS_DAS_FLIP_NFLAG:
case XFS_DAS_ALLOC_NODE:
return xfs_attr_node_addname(dac);
case XFS_DAS_UNINIT:
break;
default:
...assert on the XFS_DAS_RM_* flags...
}

if (xfs_attr_is_shortform(dp))
return xfs_attr_set_shortform(args, leaf_bp);

if (*leaf_bp != NULL) {
...release bhold...
}

if (!xfs_bmap_one_block(...))
return xfs_attr_node_addname(dac);

error = xfs_attr_leaf_try_add(args, *leaf_bp);
switch (error) {
...handle -ENOSPC and 0...
}
return error;

> }
>
> @@ -723,28 +790,30 @@ xfs_attr_leaf_try_add(
> *
> * This leaf block cannot have a "remote" value, we only call this routine
> * if bmap_one_block() says there is only one block (ie: no remote blks).
> + *
> + * This routine is meant to function as a delayed operation, and may return
> + * -EAGAIN when the transaction needs to be rolled. Calling functions will need
> + * to handle this, and recall the function until a successful error code is
> + * returned.
> */
> STATIC int
> xfs_attr_leaf_addname(
> - struct xfs_da_args *args)
> + struct xfs_delattr_context *dac)
> {
> - int error, forkoff;
> - struct xfs_buf *bp = NULL;
> - struct xfs_inode *dp = args->dp;
> -
> - trace_xfs_attr_leaf_addname(args);
> -
> - error = xfs_attr_leaf_try_add(args, bp);
> - if (error)
> - return error;
> + struct xfs_da_args *args = dac->da_args;
> + struct xfs_buf *bp = NULL;
> + int error, forkoff;
> + struct xfs_inode *dp = args->dp;
>
> - /*
> - * Commit the transaction that added the attr name so that
> - * later routines can manage their own transactions.
> - */
> - error = xfs_trans_roll_inode(&args->trans, dp);
> - if (error)
> - return error;
> + /* State machine switch */
> + switch (dac->dela_state) {
> + case XFS_DAS_FLIP_LFLAG:
> + goto das_flip_flag;
> + case XFS_DAS_RM_LBLK:
> + goto das_rm_lblk;
> + default:
> + break;
> + }
>
> /*
> * If there was an out-of-line value, allocate the blocks we
> @@ -752,12 +821,34 @@ xfs_attr_leaf_addname(
> * 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) {
> - error = xfs_attr_rmtval_set(args);
> +
> + /* Open coded xfs_attr_rmtval_set without trans handling */
> + if ((dac->flags & XFS_DAC_LEAF_ADDNAME_INIT) == 0) {
> + dac->flags |= XFS_DAC_LEAF_ADDNAME_INIT;
> + if (args->rmtblkno > 0) {
> + error = xfs_attr_rmtval_find_space(dac);
> + if (error)
> + return error;
> + }
> + }
> +
> + /*
> + * Roll through the "value", allocating blocks on disk as
> + * required.
> + */
> + if (dac->blkcnt > 0) {
> + error = xfs_attr_rmtval_set_blk(dac);
> if (error)
> return error;
> +
> + dac->flags |= XFS_DAC_DEFER_FINISH;
> + return -EAGAIN;

What state are we in here? FOUND_LBLK, with blkcnt slowly decreasing?

> }
>
> + error = xfs_attr_rmtval_set_value(args);
> + if (error)
> + return error;
> +
> if (!(args->op_flags & XFS_DA_OP_RENAME)) {
> /*
> * Added a "remote" value, just clear the incomplete flag.
> @@ -777,29 +868,29 @@ xfs_attr_leaf_addname(
> * 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)
> return error;
> /*
> * Commit the flag value change and start the next trans in series.
> */
> - error = xfs_trans_roll_inode(&args->trans, args->dp);
> - if (error)
> - return error;
> -
> + dac->dela_state = XFS_DAS_FLIP_LFLAG;
> + return -EAGAIN;
> +das_flip_flag:
> /*
> * 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;
> +das_rm_lblk:
> if (args->rmtblkno) {
> - error = xfs_attr_rmtval_invalidate(args);
> - if (error)
> - return error;
> -
> - error = xfs_attr_rmtval_remove(args);
> + error = __xfs_attr_rmtval_remove(dac);
> + if (error == -EAGAIN)
> + dac->dela_state = XFS_DAS_RM_LBLK;
> if (error)
> return error;
> }
> @@ -965,23 +1056,38 @@ xfs_attr_node_hasname(
> *
> * "Remote" attribute values confuse the issue and atomic rename operations
> * add a whole extra layer of confusion on top of that.
> + *
> + * This routine is meant to function as a delayed operation, and may return
> + * -EAGAIN when the transaction needs to be rolled. Calling functions will need
> + * to handle this, and recall the function until a successful error code is
> + *returned.
> */
> STATIC int
> xfs_attr_node_addname(
> - struct xfs_da_args *args)
> + struct xfs_delattr_context *dac)
> {
> - struct xfs_da_state *state;
> - struct xfs_da_state_blk *blk;
> - struct xfs_inode *dp;
> - int retval, error;
> + struct xfs_da_args *args = dac->da_args;
> + struct xfs_da_state *state = NULL;
> + struct xfs_da_state_blk *blk;
> + int retval = 0;
> + int error = 0;
>
> trace_xfs_attr_node_addname(args);
>
> - /*
> - * Fill in bucket of arguments/results/context to carry around.
> - */
> - dp = args->dp;
> -restart:
> + /* State machine switch */
> + switch (dac->dela_state) {
> + case XFS_DAS_FLIP_NFLAG:
> + goto das_flip_flag;
> + case XFS_DAS_FOUND_NBLK:
> + goto das_found_nblk;
> + case XFS_DAS_ALLOC_NODE:
> + goto das_alloc_node;
> + case XFS_DAS_RM_NBLK:
> + goto das_rm_nblk;
> + default:
> + break;
> + }
> +
> /*
> * Search to see if name already exists, and get back a pointer
> * to where it should go.
> @@ -1027,19 +1133,13 @@ xfs_attr_node_addname(
> error = xfs_attr3_leaf_to_node(args);
> if (error)
> goto out;
> - error = xfs_defer_finish(&args->trans);
> - if (error)
> - goto out;
>
> /*
> - * Commit the node conversion and start the next
> - * trans in the chain.
> + * Restart routine from the top. No need to set the
> + * state
> */
> - error = xfs_trans_roll_inode(&args->trans, dp);
> - if (error)
> - goto out;
> -
> - goto restart;
> + dac->flags |= XFS_DAC_DEFER_FINISH;
> + return -EAGAIN;

What state are we in here? Are we still in the same state that we were
at the start of the function, but ready to try xfs_attr3_leaf_add again?

> }
>
> /*
> @@ -1051,9 +1151,7 @@ xfs_attr_node_addname(
> error = xfs_da3_split(state);
> if (error)
> goto out;
> - error = xfs_defer_finish(&args->trans);
> - if (error)
> - goto out;
> + dac->flags |= XFS_DAC_DEFER_FINISH;
> } else {
> /*
> * Addition succeeded, update Btree hashvals.
> @@ -1068,13 +1166,9 @@ xfs_attr_node_addname(
> xfs_da_state_free(state);
> state = NULL;
>
> - /*
> - * Commit the leaf addition or btree split and start the next
> - * trans in the chain.
> - */
> - error = xfs_trans_roll_inode(&args->trans, dp);
> - if (error)
> - goto out;
> + dac->dela_state = XFS_DAS_FOUND_NBLK;
> + return -EAGAIN;
> +das_found_nblk:
>
> /*
> * If there was an out-of-line value, allocate the blocks we
> @@ -1083,7 +1177,27 @@ xfs_attr_node_addname(
> * maximum size of a transaction and/or hit a deadlock.
> */
> if (args->rmtblkno > 0) {
> - error = xfs_attr_rmtval_set(args);
> + /* Open coded xfs_attr_rmtval_set without trans handling */
> + error = xfs_attr_rmtval_find_space(dac);
> + if (error)
> + return error;
> +
> + /*
> + * Roll through the "value", allocating blocks on disk as
> + * required.
> + */
> +das_alloc_node:
> + if (dac->blkcnt > 0) {
> + error = xfs_attr_rmtval_set_blk(dac);
> + if (error)
> + return error;
> +
> + dac->flags |= XFS_DAC_DEFER_FINISH;
> + dac->dela_state = XFS_DAS_ALLOC_NODE;
> + return -EAGAIN;
> + }
> +
> + error = xfs_attr_rmtval_set_value(args);
> if (error)
> return error;
> }
> @@ -1113,22 +1227,28 @@ xfs_attr_node_addname(
> /*
> * Commit the flag value change and start the next trans in series
> */
> - error = xfs_trans_roll_inode(&args->trans, args->dp);
> - if (error)
> - goto out;
> -
> + dac->dela_state = XFS_DAS_FLIP_NFLAG;
> + return -EAGAIN;
> +das_flip_flag:
> /*
> * 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;
> +
> +das_rm_nblk:
> if (args->rmtblkno) {
> - error = xfs_attr_rmtval_invalidate(args);
> - if (error)
> - return error;
> + error = __xfs_attr_rmtval_remove(dac);
> +
> + if (error == -EAGAIN) {
> + dac->dela_state = XFS_DAS_RM_NBLK;
> + return -EAGAIN;
> + }
>
> - error = xfs_attr_rmtval_remove(args);
> if (error)
> return error;
> }
> diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
> index 64dcf0f..501f9df 100644
> --- a/fs/xfs/libxfs/xfs_attr.h
> +++ b/fs/xfs/libxfs/xfs_attr.h
> @@ -106,6 +106,118 @@ struct xfs_attr_list_context {
> * v │
> * done <─────┘
> *
> + *
> + * Below is a state machine diagram for attr set operations.
> + *
> + * xfs_attr_set_iter()
> + * │
> + * v

I think this diagram is missing the part where we attempt to add a
shortform attr?

--D

> + * ┌───n── fork has
> + * │ only 1 blk?
> + * │ │
> + * │ y
> + * │ │
> + * │ v
> + * │ xfs_attr_leaf_try_add()
> + * │ │
> + * │ v
> + * │ had enough
> + * ├───n────space?
> + * │ │
> + * │ y
> + * │ │
> + * │ v
> + * │ XFS_DAS_FOUND_LBLK ──┐
> + * │ │
> + * │ XFS_DAS_FLIP_LFLAG ──┤
> + * │ (subroutine state) │
> + * │ │
> + * │ └─>xfs_attr_leaf_addname()
> + * │ │
> + * │ v
> + * │ was this
> + * │ a rename? ──n─┐
> + * │ │ │
> + * │ y │
> + * │ │ │
> + * │ v │
> + * │ flip incomplete │
> + * │ flag │
> + * │ │ │
> + * │ v │
> + * │ XFS_DAS_FLIP_LFLAG │
> + * │ │ │
> + * │ v │
> + * │ remove │
> + * │ XFS_DAS_RM_LBLK ─> old name │
> + * │ ^ │ │
> + * │ │ v │
> + * │ └──────y── more to │
> + * │ remove │
> + * │ │ │
> + * │ n │
> + * │ │ │
> + * │ v │
> + * │ done <──────┘
> + * └──> XFS_DAS_FOUND_NBLK ──┐
> + * (subroutine state) │
> + * │
> + * XFS_DAS_ALLOC_NODE ──┤
> + * (subroutine state) │
> + * │
> + * XFS_DAS_FLIP_NFLAG ──┤
> + * (subroutine state) │
> + * │
> + * └─>xfs_attr_node_addname()
> + * │
> + * v
> + * find space to store
> + * attr. Split if needed
> + * │
> + * v
> + * XFS_DAS_FOUND_NBLK
> + * │
> + * v
> + * ┌─────n── need to
> + * │ alloc blks?
> + * │ │
> + * │ y
> + * │ │
> + * │ v
> + * │ ┌─>XFS_DAS_ALLOC_NODE
> + * │ │ │
> + * │ │ v
> + * │ └──y── need to alloc
> + * │ more blocks?
> + * │ │
> + * │ n
> + * │ │
> + * │ v
> + * │ was this
> + * └────────> a rename? ──n─┐
> + * │ │
> + * y │
> + * │ │
> + * v │
> + * flip incomplete │
> + * flag │
> + * │ │
> + * v │
> + * XFS_DAS_FLIP_NFLAG │
> + * │ │
> + * v │
> + * remove │
> + * XFS_DAS_RM_NBLK ─> old name │
> + * ^ │ │
> + * │ v │
> + * └──────y── more to │
> + * remove │
> + * │ │
> + * n │
> + * │ │
> + * v │
> + * done <──────┘
> + *
> */
>
> /*
> @@ -120,6 +232,13 @@ struct xfs_attr_list_context {
> enum xfs_delattr_state {
> XFS_DAS_UNINIT = 0, /* No state has been set yet */
> XFS_DAS_RM_SHRINK, /* We are shrinking the tree */
> + XFS_DAS_FOUND_LBLK, /* We found leaf blk for attr */
> + XFS_DAS_FOUND_NBLK, /* We found node blk for attr */
> + XFS_DAS_FLIP_LFLAG, /* Flipped leaf INCOMPLETE attr flag */
> + XFS_DAS_RM_LBLK, /* A rename is removing leaf blocks */
> + XFS_DAS_ALLOC_NODE, /* We are allocating node blocks */
> + XFS_DAS_FLIP_NFLAG, /* Flipped node INCOMPLETE attr flag */
> + XFS_DAS_RM_NBLK, /* A rename is removing node blocks */
> };
>
> /*
> @@ -127,6 +246,7 @@ enum xfs_delattr_state {
> */
> #define XFS_DAC_DEFER_FINISH 0x01 /* finish the transaction */
> #define XFS_DAC_NODE_RMVNAME_INIT 0x02 /* xfs_attr_node_removename init */
> +#define XFS_DAC_LEAF_ADDNAME_INIT 0x04 /* xfs_attr_leaf_addname init*/
>
> /*
> * Context used for keeping track of delayed attribute operations
> @@ -134,6 +254,11 @@ enum xfs_delattr_state {
> struct xfs_delattr_context {
> struct xfs_da_args *da_args;
>
> + /* Used in xfs_attr_rmtval_set_blk to roll through allocating blocks */
> + struct xfs_bmbt_irec map;
> + xfs_dablk_t lblkno;
> + int blkcnt;
> +
> /* Used in xfs_attr_node_removename to roll through removing blocks */
> struct xfs_da_state *da_state;
>
> @@ -160,7 +285,6 @@ int xfs_attr_set_args(struct xfs_da_args *args);
> int xfs_has_attr(struct xfs_da_args *args);
> int xfs_attr_remove_args(struct xfs_da_args *args);
> int xfs_attr_remove_iter(struct xfs_delattr_context *dac);
> -int xfs_attr_trans_roll(struct xfs_delattr_context *dac);
> bool xfs_attr_namecheck(const void *name, size_t length);
> void xfs_delattr_context_init(struct xfs_delattr_context *dac,
> struct xfs_da_args *args);
> diff --git a/fs/xfs/libxfs/xfs_attr_remote.c b/fs/xfs/libxfs/xfs_attr_remote.c
> index 1426c15..5b445e7 100644
> --- a/fs/xfs/libxfs/xfs_attr_remote.c
> +++ b/fs/xfs/libxfs/xfs_attr_remote.c
> @@ -441,7 +441,7 @@ xfs_attr_rmtval_get(
> * Find a "hole" in the attribute address space large enough for us to drop the
> * new attribute's value into
> */
> -STATIC int
> +int
> xfs_attr_rmt_find_hole(
> struct xfs_da_args *args)
> {
> @@ -468,7 +468,7 @@ xfs_attr_rmt_find_hole(
> return 0;
> }
>
> -STATIC int
> +int
> xfs_attr_rmtval_set_value(
> struct xfs_da_args *args)
> {
> @@ -628,6 +628,69 @@ xfs_attr_rmtval_set(
> }
>
> /*
> + * Find a hole for the attr and store it in the delayed attr context. This
> + * initializes the context to roll through allocating an attr extent for a
> + * delayed attr operation
> + */
> +int
> +xfs_attr_rmtval_find_space(
> + struct xfs_delattr_context *dac)
> +{
> + struct xfs_da_args *args = dac->da_args;
> + struct xfs_bmbt_irec *map = &dac->map;
> + int error;
> +
> + dac->lblkno = 0;
> + dac->blkcnt = 0;
> + args->rmtblkcnt = 0;
> + args->rmtblkno = 0;
> + memset(map, 0, sizeof(struct xfs_bmbt_irec));
> +
> + error = xfs_attr_rmt_find_hole(args);
> + if (error)
> + return error;
> +
> + dac->blkcnt = args->rmtblkcnt;
> + dac->lblkno = args->rmtblkno;
> +
> + return 0;
> +}
> +
> +/*
> + * Write one block of the value associated with an attribute into the
> + * out-of-line buffer that we have defined for it. This is similar to a subset
> + * of xfs_attr_rmtval_set, but records the current block to the delayed attr
> + * context, and leaves transaction handling to the caller.
> + */
> +int
> +xfs_attr_rmtval_set_blk(
> + struct xfs_delattr_context *dac)
> +{
> + struct xfs_da_args *args = dac->da_args;
> + struct xfs_inode *dp = args->dp;
> + struct xfs_bmbt_irec *map = &dac->map;
> + int nmap;
> + int error;
> +
> + nmap = 1;
> + error = xfs_bmapi_write(args->trans, dp, (xfs_fileoff_t)dac->lblkno,
> + dac->blkcnt, XFS_BMAPI_ATTRFORK, args->total,
> + map, &nmap);
> + if (error)
> + return error;
> +
> + ASSERT(nmap == 1);
> + ASSERT((map->br_startblock != DELAYSTARTBLOCK) &&
> + (map->br_startblock != HOLESTARTBLOCK));
> +
> + /* roll attribute extent map forwards */
> + dac->lblkno += map->br_blockcount;
> + dac->blkcnt -= map->br_blockcount;
> +
> + return 0;
> +}
> +
> +/*
> * Remove the value associated with an attribute by deleting the
> * out-of-line buffer that it is stored on.
> */
> @@ -669,38 +732,6 @@ xfs_attr_rmtval_invalidate(
> }
>
> /*
> - * Remove the value associated with an attribute by deleting the
> - * out-of-line buffer that it is stored on.
> - */
> -int
> -xfs_attr_rmtval_remove(
> - struct xfs_da_args *args)
> -{
> - int error;
> - struct xfs_delattr_context dac = {
> - .da_args = args,
> - };
> -
> - trace_xfs_attr_rmtval_remove(args);
> -
> - /*
> - * Keep de-allocating extents until the remote-value region is gone.
> - */
> - do {
> - error = __xfs_attr_rmtval_remove(&dac);
> - if (error != -EAGAIN)
> - break;
> -
> - error = xfs_attr_trans_roll(&dac);
> - if (error)
> - return error;
> -
> - } while (true);
> -
> - return error;
> -}
> -
> -/*
> * Remove the value associated with an attribute by deleting the out-of-line
> * buffer that it is stored on. Returns EAGAIN for the caller to refresh the
> * transaction and re-call the function
> diff --git a/fs/xfs/libxfs/xfs_attr_remote.h b/fs/xfs/libxfs/xfs_attr_remote.h
> index 002fd30..84e2700 100644
> --- a/fs/xfs/libxfs/xfs_attr_remote.h
> +++ b/fs/xfs/libxfs/xfs_attr_remote.h
> @@ -15,4 +15,8 @@ int xfs_attr_rmtval_stale(struct xfs_inode *ip, struct xfs_bmbt_irec *map,
> xfs_buf_flags_t incore_flags);
> int xfs_attr_rmtval_invalidate(struct xfs_da_args *args);
> int __xfs_attr_rmtval_remove(struct xfs_delattr_context *dac);
> +int xfs_attr_rmt_find_hole(struct xfs_da_args *args);
> +int xfs_attr_rmtval_set_value(struct xfs_da_args *args);
> +int xfs_attr_rmtval_set_blk(struct xfs_delattr_context *dac);
> +int xfs_attr_rmtval_find_space(struct xfs_delattr_context *dac);
> #endif /* __XFS_ATTR_REMOTE_H__ */
> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> index 8695165..e9dde4e 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -1925,7 +1925,6 @@ DEFINE_ATTR_EVENT(xfs_attr_refillstate);
>
> DEFINE_ATTR_EVENT(xfs_attr_rmtval_get);
> DEFINE_ATTR_EVENT(xfs_attr_rmtval_set);
> -DEFINE_ATTR_EVENT(xfs_attr_rmtval_remove);
>
> #define DEFINE_DA_EVENT(name) \
> DEFINE_EVENT(xfs_da_class, name, \
> --
> 2.7.4
>