[PATCH RESEND v18 00/11] Delay Ready Attributes

[PATCH RESEND v18 00/11] Delay Ready Attributes

[Allison Henderson]

Hi all,

This set is a subset of a larger series for Dealyed Attributes. Which is a
subset of a yet larger series for parent pointers. Delayed attributes allow
attribute operations (set and remove) to be logged and committed in the same
way that other delayed operations do. This allows more complex operations (like
parent pointers) to be broken up into multiple smaller transactions. To do
this, the existing attr operations must be modified to operate as a delayed
operation.  This means that they cannot roll, commit, or finish transactions.
Instead, they return -EAGAIN to allow the calling function to handle the
transaction.  In this series, we focus on only the delayed attribute portion.
We will introduce parent pointers in a later set.

The set as a whole is a bit much to digest at once, so I usually send out the
smaller sub series to reduce reviewer burn out.  But the entire extended series
is visible through the included github links.

This set is just a rebase and resend since the last review came back with no nits.

This series can be viewed on github here:
https://github.com/allisonhenderson/xfs_work/tree/delay_ready_attrs_v18_rebase

As well as the extended delayed attribute and parent pointer series:
https://github.com/allisonhenderson/xfs_work/tree/delay_ready_attrs_v18_extended_rebase

And the test cases:
https://github.com/allisonhenderson/xfs_work/tree/pptr_xfstestsv3

In order to run the test cases, you will need have the corresponding xfsprogs
changes as well.  Which can be found here:
https://github.com/allisonhenderson/xfs_work/tree/delay_ready_attrs_xfsprogs_v18_rebase
https://github.com/allisonhenderson/xfs_work/tree/delay_ready_attrs_xfsprogs_v18_extended_rebase

To run the xfs attributes tests run:
check -g attr

To run as delayed attributes run:
export MOUNT_OPTIONS="-o delattr"
check -g attr

To run parent pointer tests:
check -g parent

I've also made the corresponding updates to the user space side as well, and ported anything
they need to seat correctly.

Questions, comment and feedback appreciated! 

Thanks all!
Allison 

Allison Henderson (11):
  xfs: Reverse apply 72b97ea40d
  xfs: Add xfs_attr_node_remove_name
  xfs: Hoist xfs_attr_set_shortform
  xfs: Add helper xfs_attr_set_fmt
  xfs: Separate xfs_attr_node_addname and
    xfs_attr_node_addname_clear_incomplete
  xfs: Add helper xfs_attr_node_addname_find_attr
  xfs: Hoist xfs_attr_node_addname
  xfs: Hoist xfs_attr_leaf_addname
  xfs: Hoist node transaction handling
  xfs: Add delay ready attr remove routines
  xfs: Add delay ready attr set routines

 fs/xfs/libxfs/xfs_attr.c        | 897 ++++++++++++++++++++++++----------------
 fs/xfs/libxfs/xfs_attr.h        | 401 ++++++++++++++++++
 fs/xfs/libxfs/xfs_attr_leaf.c   |   2 +-
 fs/xfs/libxfs/xfs_attr_remote.c | 126 ++++--
 fs/xfs/libxfs/xfs_attr_remote.h |   7 +-
 fs/xfs/xfs_attr_inactive.c      |   2 +-
 fs/xfs/xfs_trace.h              |   2 -
 7 files changed, 1031 insertions(+), 406 deletions(-)

-- 
2.7.4

[PATCH RESEND v18 01/11] xfs: Reverse apply 72b97ea40d

[Allison Henderson]

Originally we added this patch to help modularize the attr code in
preparation for delayed attributes and the state machine it requires.
However, later reviews found that this slightly alters the transaction
handling as the helper function is ambiguous as to whether the
transaction is diry or clean.  This may cause a dirty transaction to be
included in the next roll, where previously it had not.  To preserve the
existing code flow, we reverse apply this commit.

Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
---
 fs/xfs/libxfs/xfs_attr.c | 28 +++++++++-------------------
 1 file changed, 9 insertions(+), 19 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index 96146f4..190b46d 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -1214,24 +1214,6 @@ int xfs_attr_node_removename_setup(
 	return 0;
 }
 
-STATIC int
-xfs_attr_node_remove_rmt(
-	struct xfs_da_args	*args,
-	struct xfs_da_state	*state)
-{
-	int			error = 0;
-
-	error = xfs_attr_rmtval_remove(args);
-	if (error)
-		return error;
-
-	/*
-	 * Refill the state structure with buffers, the prior calls released our
-	 * buffers.
-	 */
-	return xfs_attr_refillstate(state);
-}
-
 /*
  * Remove a name from a B-tree attribute list.
  *
@@ -1260,7 +1242,15 @@ xfs_attr_node_removename(
 	 * overflow the maximum size of a transaction and/or hit a deadlock.
 	 */
 	if (args->rmtblkno > 0) {
-		error = xfs_attr_node_remove_rmt(args, state);
+		error = xfs_attr_rmtval_remove(args);
+		if (error)
+			goto out;
+
+		/*
+		 * Refill the state structure with buffers, the prior calls
+		 * released our buffers.
+		 */
+		error = xfs_attr_refillstate(state);
 		if (error)
 			goto out;
 	}
-- 
2.7.4

Re: [PATCH RESEND v18 01/11] xfs: Reverse apply 72b97ea40d

[Darrick J. Wong]

On Wed, May 12, 2021 at 09:13:58AM -0700, Allison Henderson wrote:
> Originally we added this patch to help modularize the attr code in
> preparation for delayed attributes and the state machine it requires.
> However, later reviews found that this slightly alters the transaction
> handling as the helper function is ambiguous as to whether the
> transaction is diry or clean.  This may cause a dirty transaction to be
> included in the next roll, where previously it had not.  To preserve the
> existing code flow, we reverse apply this commit.
> 
> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> Reviewed-by: Brian Foster <bfoster@redhat.com>
> Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>

Looks fine I guess...
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
>  fs/xfs/libxfs/xfs_attr.c | 28 +++++++++-------------------
>  1 file changed, 9 insertions(+), 19 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index 96146f4..190b46d 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
> @@ -1214,24 +1214,6 @@ int xfs_attr_node_removename_setup(
>  	return 0;
>  }
>  
> -STATIC int
> -xfs_attr_node_remove_rmt(
> -	struct xfs_da_args	*args,
> -	struct xfs_da_state	*state)
> -{
> -	int			error = 0;
> -
> -	error = xfs_attr_rmtval_remove(args);
> -	if (error)
> -		return error;
> -
> -	/*
> -	 * Refill the state structure with buffers, the prior calls released our
> -	 * buffers.
> -	 */
> -	return xfs_attr_refillstate(state);
> -}
> -
>  /*
>   * Remove a name from a B-tree attribute list.
>   *
> @@ -1260,7 +1242,15 @@ xfs_attr_node_removename(
>  	 * overflow the maximum size of a transaction and/or hit a deadlock.
>  	 */
>  	if (args->rmtblkno > 0) {
> -		error = xfs_attr_node_remove_rmt(args, state);
> +		error = xfs_attr_rmtval_remove(args);
> +		if (error)
> +			goto out;
> +
> +		/*
> +		 * Refill the state structure with buffers, the prior calls
> +		 * released our buffers.
> +		 */
> +		error = xfs_attr_refillstate(state);
>  		if (error)
>  			goto out;
>  	}
> -- 
> 2.7.4
> 

[PATCH RESEND v18 02/11] xfs: Add xfs_attr_node_remove_name

[Allison Henderson]

This patch pulls a new helper function xfs_attr_node_remove_name out
of xfs_attr_node_remove_step.  This helps to modularize
xfs_attr_node_remove_step which will help make the delayed attribute
code easier to follow

Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Brian Foster <bfoster@redhat.com>
---
 fs/xfs/libxfs/xfs_attr.c | 29 ++++++++++++++++++++---------
 1 file changed, 20 insertions(+), 9 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index 190b46d..8a08d5b 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -1214,6 +1214,25 @@ int xfs_attr_node_removename_setup(
 	return 0;
 }
 
+STATIC int
+xfs_attr_node_remove_name(
+	struct xfs_da_args	*args,
+	struct xfs_da_state	*state)
+{
+	struct xfs_da_state_blk	*blk;
+	int			retval;
+
+	/*
+	 * Remove the name and update the hashvals in the tree.
+	 */
+	blk = &state->path.blk[state->path.active-1];
+	ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
+	retval = xfs_attr3_leaf_remove(blk->bp, args);
+	xfs_da3_fixhashpath(state, &state->path);
+
+	return retval;
+}
+
 /*
  * Remove a name from a B-tree attribute list.
  *
@@ -1226,7 +1245,6 @@ xfs_attr_node_removename(
 	struct xfs_da_args	*args)
 {
 	struct xfs_da_state	*state;
-	struct xfs_da_state_blk	*blk;
 	int			retval, error;
 	struct xfs_inode	*dp = args->dp;
 
@@ -1254,14 +1272,7 @@ xfs_attr_node_removename(
 		if (error)
 			goto out;
 	}
-
-	/*
-	 * Remove the name and update the hashvals in the tree.
-	 */
-	blk = &state->path.blk[ state->path.active-1 ];
-	ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
-	retval = xfs_attr3_leaf_remove(blk->bp, args);
-	xfs_da3_fixhashpath(state, &state->path);
+	retval = xfs_attr_node_remove_name(args, state);
 
 	/*
 	 * Check to see if the tree needs to be collapsed.
-- 
2.7.4

[PATCH RESEND v18 03/11] xfs: Hoist xfs_attr_set_shortform

[Allison Henderson]

This patch hoists xfs_attr_set_shortform into the calling function. This
will help keep all state management code in the same scope.

Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
---
 fs/xfs/libxfs/xfs_attr.c | 81 ++++++++++++++++--------------------------------
 1 file changed, 27 insertions(+), 54 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index 8a08d5b..32133a0 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -237,53 +237,6 @@ 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.
- */
-STATIC int
-xfs_attr_set_shortform(
-	struct xfs_da_args	*args,
-	struct xfs_buf		**leaf_bp)
-{
-	struct xfs_inode	*dp = args->dp;
-	int			error, error2 = 0;
-
-	/*
-	 * Try to add the attr to the attribute list in the inode.
-	 */
-	error = xfs_attr_try_sf_addname(dp, args);
-	if (error != -ENOSPC) {
-		error2 = xfs_trans_commit(args->trans);
-		args->trans = NULL;
-		return error ? error : error2;
-	}
-	/*
-	 * It won't fit in the shortform, transform to a leaf block.  GROT:
-	 * another possible req'mt for a double-split btree op.
-	 */
-	error = xfs_attr_shortform_to_leaf(args, leaf_bp);
-	if (error)
-		return error;
-
-	/*
-	 * 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.
-	 */
-	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;
-}
-
-/*
  * Set the attribute specified in @args.
  */
 int
@@ -292,7 +245,7 @@ xfs_attr_set_args(
 {
 	struct xfs_inode	*dp = args->dp;
 	struct xfs_buf          *leaf_bp = NULL;
-	int			error = 0;
+	int			error2, error = 0;
 
 	/*
 	 * If the attribute list is already in leaf format, jump straight to
@@ -301,16 +254,36 @@ xfs_attr_set_args(
 	 * again.
 	 */
 	if (xfs_attr_is_shortform(dp)) {
+		/*
+		 * Try to add the attr to the attribute list in the inode.
+		 */
+		error = xfs_attr_try_sf_addname(dp, args);
+		if (error != -ENOSPC) {
+			error2 = xfs_trans_commit(args->trans);
+			args->trans = NULL;
+			return error ? error : error2;
+		}
+
+		/*
+		 * It won't fit in the shortform, transform to a leaf block.
+		 * GROT: another possible req'mt for a double-split btree op.
+		 */
+		error = xfs_attr_shortform_to_leaf(args, &leaf_bp);
+		if (error)
+			return error;
 
 		/*
-		 * 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.
+		 * 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.
 		 */
-		error = xfs_attr_set_shortform(args, &leaf_bp);
-		if (error || !args->trans)
+		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;
+		}
 	}
 
 	if (xfs_attr_is_leaf(dp)) {
-- 
2.7.4

[PATCH RESEND v18 04/11] xfs: Add helper xfs_attr_set_fmt

[Allison Henderson]

This patch adds a helper function xfs_attr_set_fmt.  This will help
isolate the code that will require state management from the portions
that do not.  xfs_attr_set_fmt returns 0 when the attr has been set and
no further action is needed.  It returns -EAGAIN when shortform has been
transformed to leaf, and the calling function should proceed the set the
attr in leaf form.

Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
---
 fs/xfs/libxfs/xfs_attr.c | 79 ++++++++++++++++++++++++++++--------------------
 1 file changed, 46 insertions(+), 33 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index 32133a0..1a618a2 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -236,6 +236,48 @@ xfs_attr_is_shortform(
 		ip->i_afp->if_nextents == 0);
 }
 
+STATIC int
+xfs_attr_set_fmt(
+	struct xfs_da_args	*args)
+{
+	struct xfs_buf          *leaf_bp = NULL;
+	struct xfs_inode	*dp = args->dp;
+	int			error2, error = 0;
+
+	/*
+	 * Try to add the attr to the attribute list in the inode.
+	 */
+	error = xfs_attr_try_sf_addname(dp, args);
+	if (error != -ENOSPC) {
+		error2 = xfs_trans_commit(args->trans);
+		args->trans = NULL;
+		return error ? error : error2;
+	}
+
+	/*
+	 * It won't fit in the shortform, transform to a leaf block.
+	 * GROT: another possible req'mt for a double-split btree op.
+	 */
+	error = xfs_attr_shortform_to_leaf(args, &leaf_bp);
+	if (error)
+		return error;
+
+	/*
+	 * 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.
+	 */
+	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 -EAGAIN;
+}
+
 /*
  * Set the attribute specified in @args.
  */
@@ -244,8 +286,7 @@ xfs_attr_set_args(
 	struct xfs_da_args	*args)
 {
 	struct xfs_inode	*dp = args->dp;
-	struct xfs_buf          *leaf_bp = NULL;
-	int			error2, error = 0;
+	int			error;
 
 	/*
 	 * If the attribute list is already in leaf format, jump straight to
@@ -254,36 +295,9 @@ xfs_attr_set_args(
 	 * again.
 	 */
 	if (xfs_attr_is_shortform(dp)) {
-		/*
-		 * Try to add the attr to the attribute list in the inode.
-		 */
-		error = xfs_attr_try_sf_addname(dp, args);
-		if (error != -ENOSPC) {
-			error2 = xfs_trans_commit(args->trans);
-			args->trans = NULL;
-			return error ? error : error2;
-		}
-
-		/*
-		 * It won't fit in the shortform, transform to a leaf block.
-		 * GROT: another possible req'mt for a double-split btree op.
-		 */
-		error = xfs_attr_shortform_to_leaf(args, &leaf_bp);
-		if (error)
-			return error;
-
-		/*
-		 * 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.
-		 */
-		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);
+		error = xfs_attr_set_fmt(args);
+		if (error != -EAGAIN)
 			return error;
-		}
 	}
 
 	if (xfs_attr_is_leaf(dp)) {
@@ -317,8 +331,7 @@ xfs_attr_set_args(
 			return error;
 	}
 
-	error = xfs_attr_node_addname(args);
-	return error;
+	return xfs_attr_node_addname(args);
 }
 
 /*
-- 
2.7.4

Re: [PATCH RESEND v18 04/11] xfs: Add helper xfs_attr_set_fmt

[Darrick J. Wong]

On Wed, May 12, 2021 at 09:14:01AM -0700, Allison Henderson wrote:
> This patch adds a helper function xfs_attr_set_fmt.  This will help
> isolate the code that will require state management from the portions
> that do not.  xfs_attr_set_fmt returns 0 when the attr has been set and
> no further action is needed.  It returns -EAGAIN when shortform has been
> transformed to leaf, and the calling function should proceed the set the
> attr in leaf form.
> 
> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
> Reviewed-by: Brian Foster <bfoster@redhat.com>

Er... can't you combine patches 3 and 4 into a single patch that
renames xfs_attr_set_shortform -> xfs_attr_set_fmt and drops the
**leafbp parameter?  Smushing the two together it's a bit more obvious
what's really changing here (which really isn't that much!) so:

Reviewed-by: Darrick J. Wong <djwong@kernel.org>

(Though I think I would like the two combined for v19.  But let's see
what I think of the whole series by the time I reach the end, eh? :) )

--D

> ---
>  fs/xfs/libxfs/xfs_attr.c | 79 ++++++++++++++++++++++++++++--------------------
>  1 file changed, 46 insertions(+), 33 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index 32133a0..1a618a2 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
> @@ -236,6 +236,48 @@ xfs_attr_is_shortform(
>  		ip->i_afp->if_nextents == 0);
>  }
>  
> +STATIC int
> +xfs_attr_set_fmt(
> +	struct xfs_da_args	*args)
> +{
> +	struct xfs_buf          *leaf_bp = NULL;
> +	struct xfs_inode	*dp = args->dp;
> +	int			error2, error = 0;
> +
> +	/*
> +	 * Try to add the attr to the attribute list in the inode.
> +	 */
> +	error = xfs_attr_try_sf_addname(dp, args);
> +	if (error != -ENOSPC) {
> +		error2 = xfs_trans_commit(args->trans);
> +		args->trans = NULL;
> +		return error ? error : error2;
> +	}
> +
> +	/*
> +	 * It won't fit in the shortform, transform to a leaf block.
> +	 * GROT: another possible req'mt for a double-split btree op.
> +	 */
> +	error = xfs_attr_shortform_to_leaf(args, &leaf_bp);
> +	if (error)
> +		return error;
> +
> +	/*
> +	 * 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.
> +	 */
> +	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 -EAGAIN;
> +}
> +
>  /*
>   * Set the attribute specified in @args.
>   */
> @@ -244,8 +286,7 @@ xfs_attr_set_args(
>  	struct xfs_da_args	*args)
>  {
>  	struct xfs_inode	*dp = args->dp;
> -	struct xfs_buf          *leaf_bp = NULL;
> -	int			error2, error = 0;
> +	int			error;
>  
>  	/*
>  	 * If the attribute list is already in leaf format, jump straight to
> @@ -254,36 +295,9 @@ xfs_attr_set_args(
>  	 * again.
>  	 */
>  	if (xfs_attr_is_shortform(dp)) {
> -		/*
> -		 * Try to add the attr to the attribute list in the inode.
> -		 */
> -		error = xfs_attr_try_sf_addname(dp, args);
> -		if (error != -ENOSPC) {
> -			error2 = xfs_trans_commit(args->trans);
> -			args->trans = NULL;
> -			return error ? error : error2;
> -		}
> -
> -		/*
> -		 * It won't fit in the shortform, transform to a leaf block.
> -		 * GROT: another possible req'mt for a double-split btree op.
> -		 */
> -		error = xfs_attr_shortform_to_leaf(args, &leaf_bp);
> -		if (error)
> -			return error;
> -
> -		/*
> -		 * 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.
> -		 */
> -		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);
> +		error = xfs_attr_set_fmt(args);
> +		if (error != -EAGAIN)
>  			return error;
> -		}
>  	}
>  
>  	if (xfs_attr_is_leaf(dp)) {
> @@ -317,8 +331,7 @@ xfs_attr_set_args(
>  			return error;
>  	}
>  
> -	error = xfs_attr_node_addname(args);
> -	return error;
> +	return xfs_attr_node_addname(args);
>  }
>  
>  /*
> -- 
> 2.7.4
> 

Re: [PATCH RESEND v18 04/11] xfs: Add helper xfs_attr_set_fmt

[Allison Henderson]

On 5/13/21 4:46 PM, Darrick J. Wong wrote:
> On Wed, May 12, 2021 at 09:14:01AM -0700, Allison Henderson wrote:
>> This patch adds a helper function xfs_attr_set_fmt.  This will help
>> isolate the code that will require state management from the portions
>> that do not.  xfs_attr_set_fmt returns 0 when the attr has been set and
>> no further action is needed.  It returns -EAGAIN when shortform has been
>> transformed to leaf, and the calling function should proceed the set the
>> attr in leaf form.
>>
>> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
>> Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
>> Reviewed-by: Brian Foster <bfoster@redhat.com>
> 
> Er... can't you combine patches 3 and 4 into a single patch that
> renames xfs_attr_set_shortform -> xfs_attr_set_fmt and drops the
> **leafbp parameter?  Smushing the two together it's a bit more obvious
> what's really changing here (which really isn't that much!) so:
> 
> Reviewed-by: Darrick J. Wong <djwong@kernel.org>
> 
> (Though I think I would like the two combined for v19.  But let's see
> what I think of the whole series by the time I reach the end, eh? :) )
So... did your feelings change much by the end of the set?  I have to 
admit, looking at the combination of these two patches, the diff does 
not look particularly attractive.  During all our refactoring efforts, I 
think we did a little bit of a circle between these two.

Rather than sending out a v19 with a poor patch that will most certainly 
result in a v20... how about I slap them together, and send them out in 
an RFC explaining what it is?  That way people can look at it and we can 
discuss what we really want to keep.  Because from looking at the diff, 
there's really only a few bits of functional changes, that would 
probably be appropriate to lump in with patch 11 if everyone is in 
agreement.  Then possibly just drop 3 and 4?

Allison


> 
> --D
> 
>> ---
>>   fs/xfs/libxfs/xfs_attr.c | 79 ++++++++++++++++++++++++++++--------------------
>>   1 file changed, 46 insertions(+), 33 deletions(-)
>>
>> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
>> index 32133a0..1a618a2 100644
>> --- a/fs/xfs/libxfs/xfs_attr.c
>> +++ b/fs/xfs/libxfs/xfs_attr.c
>> @@ -236,6 +236,48 @@ xfs_attr_is_shortform(
>>   		ip->i_afp->if_nextents == 0);
>>   }
>>   
>> +STATIC int
>> +xfs_attr_set_fmt(
>> +	struct xfs_da_args	*args)
>> +{
>> +	struct xfs_buf          *leaf_bp = NULL;
>> +	struct xfs_inode	*dp = args->dp;
>> +	int			error2, error = 0;
>> +
>> +	/*
>> +	 * Try to add the attr to the attribute list in the inode.
>> +	 */
>> +	error = xfs_attr_try_sf_addname(dp, args);
>> +	if (error != -ENOSPC) {
>> +		error2 = xfs_trans_commit(args->trans);
>> +		args->trans = NULL;
>> +		return error ? error : error2;
>> +	}
>> +
>> +	/*
>> +	 * It won't fit in the shortform, transform to a leaf block.
>> +	 * GROT: another possible req'mt for a double-split btree op.
>> +	 */
>> +	error = xfs_attr_shortform_to_leaf(args, &leaf_bp);
>> +	if (error)
>> +		return error;
>> +
>> +	/*
>> +	 * 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.
>> +	 */
>> +	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 -EAGAIN;
>> +}
>> +
>>   /*
>>    * Set the attribute specified in @args.
>>    */
>> @@ -244,8 +286,7 @@ xfs_attr_set_args(
>>   	struct xfs_da_args	*args)
>>   {
>>   	struct xfs_inode	*dp = args->dp;
>> -	struct xfs_buf          *leaf_bp = NULL;
>> -	int			error2, error = 0;
>> +	int			error;
>>   
>>   	/*
>>   	 * If the attribute list is already in leaf format, jump straight to
>> @@ -254,36 +295,9 @@ xfs_attr_set_args(
>>   	 * again.
>>   	 */
>>   	if (xfs_attr_is_shortform(dp)) {
>> -		/*
>> -		 * Try to add the attr to the attribute list in the inode.
>> -		 */
>> -		error = xfs_attr_try_sf_addname(dp, args);
>> -		if (error != -ENOSPC) {
>> -			error2 = xfs_trans_commit(args->trans);
>> -			args->trans = NULL;
>> -			return error ? error : error2;
>> -		}
>> -
>> -		/*
>> -		 * It won't fit in the shortform, transform to a leaf block.
>> -		 * GROT: another possible req'mt for a double-split btree op.
>> -		 */
>> -		error = xfs_attr_shortform_to_leaf(args, &leaf_bp);
>> -		if (error)
>> -			return error;
>> -
>> -		/*
>> -		 * 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.
>> -		 */
>> -		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);
>> +		error = xfs_attr_set_fmt(args);
>> +		if (error != -EAGAIN)
>>   			return error;
>> -		}
>>   	}
>>   
>>   	if (xfs_attr_is_leaf(dp)) {
>> @@ -317,8 +331,7 @@ xfs_attr_set_args(
>>   			return error;
>>   	}
>>   
>> -	error = xfs_attr_node_addname(args);
>> -	return error;
>> +	return xfs_attr_node_addname(args);
>>   }
>>   
>>   /*
>> -- 
>> 2.7.4
>>

Re: [PATCH RESEND v18 04/11] xfs: Add helper xfs_attr_set_fmt

[Darrick J. Wong]

On Fri, May 14, 2021 at 10:42:05PM -0700, Allison Henderson wrote:
> 
> 
> On 5/13/21 4:46 PM, Darrick J. Wong wrote:
> > On Wed, May 12, 2021 at 09:14:01AM -0700, Allison Henderson wrote:
> > > This patch adds a helper function xfs_attr_set_fmt.  This will help
> > > isolate the code that will require state management from the portions
> > > that do not.  xfs_attr_set_fmt returns 0 when the attr has been set and
> > > no further action is needed.  It returns -EAGAIN when shortform has been
> > > transformed to leaf, and the calling function should proceed the set the
> > > attr in leaf form.
> > > 
> > > Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> > > Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
> > > Reviewed-by: Brian Foster <bfoster@redhat.com>
> > 
> > Er... can't you combine patches 3 and 4 into a single patch that
> > renames xfs_attr_set_shortform -> xfs_attr_set_fmt and drops the
> > **leafbp parameter?  Smushing the two together it's a bit more obvious
> > what's really changing here (which really isn't that much!) so:
> > 
> > Reviewed-by: Darrick J. Wong <djwong@kernel.org>
> > 
> > (Though I think I would like the two combined for v19.  But let's see
> > what I think of the whole series by the time I reach the end, eh? :) )
> So... did your feelings change much by the end of the set?  I have to admit,
> looking at the combination of these two patches, the diff does not look
> particularly attractive.  During all our refactoring efforts, I think we did
> a little bit of a circle between these two.
> 
> Rather than sending out a v19 with a poor patch that will most certainly
> result in a v20... how about I slap them together, and send them out in an
> RFC explaining what it is?  That way people can look at it and we can
> discuss what we really want to keep.  Because from looking at the diff,
> there's really only a few bits of functional changes, that would probably be
> appropriate to lump in with patch 11 if everyone is in agreement.  Then
> possibly just drop 3 and 4?

Since you now have the same set of RVB tags for patches 3 and 4, I think
it's ok to combine them into a single patch with the same set of RVBs.

(As in: generate diff files for the entire stgit/quilt/guilt stack, pop
to patch 3 in the stack, apply patch 4's diff, update the commit message
for patch 3, commit patch 3, then delete patch 4 from the stack.)

Then tack all the cleanup stuffs onto the end as patches 12-whatever.

That way the cleanups happen and as far as I'm concerned you're not
making any tweaks to the v18 changes that are so large as to demand
re-review.

--D

> 
> Allison
> 
> 
> > 
> > --D
> > 
> > > ---
> > >   fs/xfs/libxfs/xfs_attr.c | 79 ++++++++++++++++++++++++++++--------------------
> > >   1 file changed, 46 insertions(+), 33 deletions(-)
> > > 
> > > diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> > > index 32133a0..1a618a2 100644
> > > --- a/fs/xfs/libxfs/xfs_attr.c
> > > +++ b/fs/xfs/libxfs/xfs_attr.c
> > > @@ -236,6 +236,48 @@ xfs_attr_is_shortform(
> > >   		ip->i_afp->if_nextents == 0);
> > >   }
> > > +STATIC int
> > > +xfs_attr_set_fmt(
> > > +	struct xfs_da_args	*args)
> > > +{
> > > +	struct xfs_buf          *leaf_bp = NULL;
> > > +	struct xfs_inode	*dp = args->dp;
> > > +	int			error2, error = 0;
> > > +
> > > +	/*
> > > +	 * Try to add the attr to the attribute list in the inode.
> > > +	 */
> > > +	error = xfs_attr_try_sf_addname(dp, args);
> > > +	if (error != -ENOSPC) {
> > > +		error2 = xfs_trans_commit(args->trans);
> > > +		args->trans = NULL;
> > > +		return error ? error : error2;
> > > +	}
> > > +
> > > +	/*
> > > +	 * It won't fit in the shortform, transform to a leaf block.
> > > +	 * GROT: another possible req'mt for a double-split btree op.
> > > +	 */
> > > +	error = xfs_attr_shortform_to_leaf(args, &leaf_bp);
> > > +	if (error)
> > > +		return error;
> > > +
> > > +	/*
> > > +	 * 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.
> > > +	 */
> > > +	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 -EAGAIN;
> > > +}
> > > +
> > >   /*
> > >    * Set the attribute specified in @args.
> > >    */
> > > @@ -244,8 +286,7 @@ xfs_attr_set_args(
> > >   	struct xfs_da_args	*args)
> > >   {
> > >   	struct xfs_inode	*dp = args->dp;
> > > -	struct xfs_buf          *leaf_bp = NULL;
> > > -	int			error2, error = 0;
> > > +	int			error;
> > >   	/*
> > >   	 * If the attribute list is already in leaf format, jump straight to
> > > @@ -254,36 +295,9 @@ xfs_attr_set_args(
> > >   	 * again.
> > >   	 */
> > >   	if (xfs_attr_is_shortform(dp)) {
> > > -		/*
> > > -		 * Try to add the attr to the attribute list in the inode.
> > > -		 */
> > > -		error = xfs_attr_try_sf_addname(dp, args);
> > > -		if (error != -ENOSPC) {
> > > -			error2 = xfs_trans_commit(args->trans);
> > > -			args->trans = NULL;
> > > -			return error ? error : error2;
> > > -		}
> > > -
> > > -		/*
> > > -		 * It won't fit in the shortform, transform to a leaf block.
> > > -		 * GROT: another possible req'mt for a double-split btree op.
> > > -		 */
> > > -		error = xfs_attr_shortform_to_leaf(args, &leaf_bp);
> > > -		if (error)
> > > -			return error;
> > > -
> > > -		/*
> > > -		 * 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.
> > > -		 */
> > > -		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);
> > > +		error = xfs_attr_set_fmt(args);
> > > +		if (error != -EAGAIN)
> > >   			return error;
> > > -		}
> > >   	}
> > >   	if (xfs_attr_is_leaf(dp)) {
> > > @@ -317,8 +331,7 @@ xfs_attr_set_args(
> > >   			return error;
> > >   	}
> > > -	error = xfs_attr_node_addname(args);
> > > -	return error;
> > > +	return xfs_attr_node_addname(args);
> > >   }
> > >   /*
> > > -- 
> > > 2.7.4
> > > 

[PATCH RESEND v18 05/11] xfs: Separate xfs_attr_node_addname and xfs_attr_node_addname_clear_incomplete

[Allison Henderson]

This patch separate xfs_attr_node_addname into two functions.  This will
help to make it easier to hoist parts of xfs_attr_node_addname that need
state management

Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
---
 fs/xfs/libxfs/xfs_attr.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index 1a618a2..5cf2e71 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -54,6 +54,7 @@ STATIC int xfs_attr_leaf_hasname(struct xfs_da_args *args, struct xfs_buf **bp);
 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_removename(xfs_da_args_t *args);
+STATIC int xfs_attr_node_addname_clear_incomplete(struct xfs_da_args *args);
 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);
@@ -1073,6 +1074,28 @@ xfs_attr_node_addname(
 			return error;
 	}
 
+	error = xfs_attr_node_addname_clear_incomplete(args);
+	if (error)
+		goto out;
+	retval = 0;
+out:
+	if (state)
+		xfs_da_state_free(state);
+	if (error)
+		return error;
+	return retval;
+}
+
+
+STATIC
+int xfs_attr_node_addname_clear_incomplete(
+	struct xfs_da_args		*args)
+{
+	struct xfs_da_state		*state = NULL;
+	struct xfs_da_state_blk		*blk;
+	int				retval = 0;
+	int				error = 0;
+
 	/*
 	 * 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.
-- 
2.7.4

Re: [PATCH RESEND v18 05/11] xfs: Separate xfs_attr_node_addname and xfs_attr_node_addname_clear_incomplete

[Darrick J. Wong]

On Wed, May 12, 2021 at 09:14:02AM -0700, Allison Henderson wrote:
> This patch separate xfs_attr_node_addname into two functions.  This will
> help to make it easier to hoist parts of xfs_attr_node_addname that need
> state management
> 
> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> Reviewed-by: Brian Foster <bfoster@redhat.com>
> Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>

Makes sense...
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
>  fs/xfs/libxfs/xfs_attr.c | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index 1a618a2..5cf2e71 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
> @@ -54,6 +54,7 @@ STATIC int xfs_attr_leaf_hasname(struct xfs_da_args *args, struct xfs_buf **bp);
>  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_removename(xfs_da_args_t *args);
> +STATIC int xfs_attr_node_addname_clear_incomplete(struct xfs_da_args *args);
>  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);
> @@ -1073,6 +1074,28 @@ xfs_attr_node_addname(
>  			return error;
>  	}
>  
> +	error = xfs_attr_node_addname_clear_incomplete(args);
> +	if (error)
> +		goto out;
> +	retval = 0;
> +out:
> +	if (state)
> +		xfs_da_state_free(state);
> +	if (error)
> +		return error;
> +	return retval;
> +}
> +
> +
> +STATIC
> +int xfs_attr_node_addname_clear_incomplete(
> +	struct xfs_da_args		*args)
> +{
> +	struct xfs_da_state		*state = NULL;
> +	struct xfs_da_state_blk		*blk;
> +	int				retval = 0;
> +	int				error = 0;
> +
>  	/*
>  	 * 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.
> -- 
> 2.7.4
> 

Re: [PATCH RESEND v18 05/11] xfs: Separate xfs_attr_node_addname and xfs_attr_node_addname_clear_incomplete

[Darrick J. Wong]

On Thu, May 13, 2021 at 04:49:13PM -0700, Darrick J. Wong wrote:
> On Wed, May 12, 2021 at 09:14:02AM -0700, Allison Henderson wrote:
> > This patch separate xfs_attr_node_addname into two functions.  This will
> > help to make it easier to hoist parts of xfs_attr_node_addname that need
> > state management
> > 
> > Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> > Reviewed-by: Brian Foster <bfoster@redhat.com>
> > Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
> 
> Makes sense...
> Reviewed-by: Darrick J. Wong <djwong@kernel.org>
> 
> --D
> 
> > ---
> >  fs/xfs/libxfs/xfs_attr.c | 23 +++++++++++++++++++++++
> >  1 file changed, 23 insertions(+)
> > 
> > diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> > index 1a618a2..5cf2e71 100644
> > --- a/fs/xfs/libxfs/xfs_attr.c
> > +++ b/fs/xfs/libxfs/xfs_attr.c
> > @@ -54,6 +54,7 @@ STATIC int xfs_attr_leaf_hasname(struct xfs_da_args *args, struct xfs_buf **bp);
> >  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_removename(xfs_da_args_t *args);
> > +STATIC int xfs_attr_node_addname_clear_incomplete(struct xfs_da_args *args);
> >  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);
> > @@ -1073,6 +1074,28 @@ xfs_attr_node_addname(
> >  			return error;
> >  	}
> >  
> > +	error = xfs_attr_node_addname_clear_incomplete(args);
> > +	if (error)
> > +		goto out;
> > +	retval = 0;
> > +out:
> > +	if (state)
> > +		xfs_da_state_free(state);
> > +	if (error)
> > +		return error;
> > +	return retval;
> > +}
> > +
> > +
> > +STATIC
> > +int xfs_attr_node_addname_clear_incomplete(

...well, so long as this gets changed to:

STATIC int
xfs_attr_node_addname_clear_incomplete

--D

> > +	struct xfs_da_args		*args)
> > +{
> > +	struct xfs_da_state		*state = NULL;
> > +	struct xfs_da_state_blk		*blk;
> > +	int				retval = 0;
> > +	int				error = 0;
> > +
> >  	/*
> >  	 * 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.
> > -- 
> > 2.7.4
> > 

Re: [PATCH RESEND v18 05/11] xfs: Separate xfs_attr_node_addname and xfs_attr_node_addname_clear_incomplete

[Allison Henderson]

On 5/13/21 5:41 PM, Darrick J. Wong wrote:
> On Thu, May 13, 2021 at 04:49:13PM -0700, Darrick J. Wong wrote:
>> On Wed, May 12, 2021 at 09:14:02AM -0700, Allison Henderson wrote:
>>> This patch separate xfs_attr_node_addname into two functions.  This will
>>> help to make it easier to hoist parts of xfs_attr_node_addname that need
>>> state management
>>>
>>> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
>>> Reviewed-by: Brian Foster <bfoster@redhat.com>
>>> Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
>>
>> Makes sense...
>> Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Great.  Thank you!

>>
>> --D
>>
>>> ---
>>>   fs/xfs/libxfs/xfs_attr.c | 23 +++++++++++++++++++++++
>>>   1 file changed, 23 insertions(+)
>>>
>>> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
>>> index 1a618a2..5cf2e71 100644
>>> --- a/fs/xfs/libxfs/xfs_attr.c
>>> +++ b/fs/xfs/libxfs/xfs_attr.c
>>> @@ -54,6 +54,7 @@ STATIC int xfs_attr_leaf_hasname(struct xfs_da_args *args, struct xfs_buf **bp);
>>>   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_removename(xfs_da_args_t *args);
>>> +STATIC int xfs_attr_node_addname_clear_incomplete(struct xfs_da_args *args);
>>>   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);
>>> @@ -1073,6 +1074,28 @@ xfs_attr_node_addname(
>>>   			return error;
>>>   	}
>>>   
>>> +	error = xfs_attr_node_addname_clear_incomplete(args);
>>> +	if (error)
>>> +		goto out;
>>> +	retval = 0;
>>> +out:
>>> +	if (state)
>>> +		xfs_da_state_free(state);
>>> +	if (error)
>>> +		return error;
>>> +	return retval;
>>> +}
>>> +
>>> +
>>> +STATIC
>>> +int xfs_attr_node_addname_clear_incomplete(
> 
> ...well, so long as this gets changed to:
> 
> STATIC int
> xfs_attr_node_addname_clear_incomplete
Sure, will fix.

> 
> --D
> 
>>> +	struct xfs_da_args		*args)
>>> +{
>>> +	struct xfs_da_state		*state = NULL;
>>> +	struct xfs_da_state_blk		*blk;
>>> +	int				retval = 0;
>>> +	int				error = 0;
>>> +
>>>   	/*
>>>   	 * 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.
>>> -- 
>>> 2.7.4
>>>

[PATCH RESEND v18 06/11] xfs: Add helper xfs_attr_node_addname_find_attr

[Allison Henderson]

This patch separates the first half of xfs_attr_node_addname into a
helper function xfs_attr_node_addname_find_attr.  It also replaces the
restart goto with an EAGAIN return code driven by a loop in the calling
function.  This looks odd now, but will clean up nicly once we introduce
the state machine.  It will also enable hoisting the last state out of
xfs_attr_node_addname with out having to plumb in a "done" parameter to
know if we need to move to the next state or not.

Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
---
 fs/xfs/libxfs/xfs_attr.c | 87 ++++++++++++++++++++++++++++++------------------
 1 file changed, 54 insertions(+), 33 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index 5cf2e71..8a60534 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -52,7 +52,10 @@ 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_da_args *args,
+				 struct xfs_da_state *state);
+STATIC int xfs_attr_node_addname_find_attr(struct xfs_da_args *args,
+				 struct xfs_da_state **state);
 STATIC int xfs_attr_node_removename(xfs_da_args_t *args);
 STATIC int xfs_attr_node_addname_clear_incomplete(struct xfs_da_args *args);
 STATIC int xfs_attr_node_hasname(xfs_da_args_t *args,
@@ -287,6 +290,7 @@ xfs_attr_set_args(
 	struct xfs_da_args	*args)
 {
 	struct xfs_inode	*dp = args->dp;
+	struct xfs_da_state     *state;
 	int			error;
 
 	/*
@@ -332,7 +336,14 @@ xfs_attr_set_args(
 			return error;
 	}
 
-	return xfs_attr_node_addname(args);
+	do {
+		error = xfs_attr_node_addname_find_attr(args, &state);
+		if (error)
+			return error;
+		error = xfs_attr_node_addname(args, state);
+	} while (error == -EAGAIN);
+
+	return error;
 }
 
 /*
@@ -896,48 +907,26 @@ xfs_attr_node_hasname(
  * External routines when attribute list size > geo->blksize
  *========================================================================*/
 
-/*
- * Add a name to a Btree-format attribute list.
- *
- * This will involve walking down the Btree, and may involve splitting
- * leaf nodes and even splitting intermediate nodes up to and including
- * the root node (a special case of an intermediate node).
- *
- * "Remote" attribute values confuse the issue and atomic rename operations
- * add a whole extra layer of confusion on top of that.
- */
 STATIC int
-xfs_attr_node_addname(
-	struct xfs_da_args	*args)
+xfs_attr_node_addname_find_attr(
+	struct xfs_da_args	*args,
+	struct xfs_da_state     **state)
 {
-	struct xfs_da_state	*state;
-	struct xfs_da_state_blk	*blk;
-	struct xfs_inode	*dp;
-	int			retval, error;
-
-	trace_xfs_attr_node_addname(args);
+	int			retval;
 
 	/*
-	 * Fill in bucket of arguments/results/context to carry around.
-	 */
-	dp = args->dp;
-restart:
-	/*
 	 * Search to see if name already exists, and get back a pointer
 	 * to where it should go.
 	 */
-	error = 0;
-	retval = xfs_attr_node_hasname(args, &state);
+	retval = xfs_attr_node_hasname(args, state);
 	if (retval != -ENOATTR && retval != -EEXIST)
-		goto out;
+		goto error;
 
-	blk = &state->path.blk[ state->path.active-1 ];
-	ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
 	if (retval == -ENOATTR && (args->attr_flags & XATTR_REPLACE))
-		goto out;
+		goto error;
 	if (retval == -EEXIST) {
 		if (args->attr_flags & XATTR_CREATE)
-			goto out;
+			goto error;
 
 		trace_xfs_attr_node_replace(args);
 
@@ -955,6 +944,38 @@ xfs_attr_node_addname(
 		args->rmtvaluelen = 0;
 	}
 
+	return 0;
+error:
+	if (*state)
+		xfs_da_state_free(*state);
+	return retval;
+}
+
+/*
+ * Add a name to a Btree-format attribute list.
+ *
+ * This will involve walking down the Btree, and may involve splitting
+ * leaf nodes and even splitting intermediate nodes up to and including
+ * the root node (a special case of an intermediate node).
+ *
+ * "Remote" attribute values confuse the issue and atomic rename operations
+ * add a whole extra layer of confusion on top of that.
+ */
+STATIC int
+xfs_attr_node_addname(
+	struct xfs_da_args	*args,
+	struct xfs_da_state	*state)
+{
+	struct xfs_da_state_blk	*blk;
+	struct xfs_inode	*dp;
+	int			retval, error;
+
+	trace_xfs_attr_node_addname(args);
+
+	dp = args->dp;
+	blk = &state->path.blk[state->path.active-1];
+	ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
+
 	retval = xfs_attr3_leaf_add(blk->bp, state->args);
 	if (retval == -ENOSPC) {
 		if (state->path.active == 1) {
@@ -980,7 +1001,7 @@ xfs_attr_node_addname(
 			if (error)
 				goto out;
 
-			goto restart;
+			return -EAGAIN;
 		}
 
 		/*
-- 
2.7.4

[PATCH RESEND v18 07/11] xfs: Hoist xfs_attr_node_addname

[Allison Henderson]

This patch hoists the later half of xfs_attr_node_addname into
the calling function.  We do this because it is this area that
will need the most state management, and we want to keep such
code in the same scope as much as possible

Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
---
 fs/xfs/libxfs/xfs_attr.c | 159 ++++++++++++++++++++++-------------------------
 1 file changed, 75 insertions(+), 84 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index 8a60534..3cc09e2 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -52,6 +52,7 @@ 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 void xfs_attr_restore_rmt_blk(struct xfs_da_args *args);
 STATIC int xfs_attr_node_addname(struct xfs_da_args *args,
 				 struct xfs_da_state *state);
 STATIC int xfs_attr_node_addname_find_attr(struct xfs_da_args *args,
@@ -290,8 +291,8 @@ xfs_attr_set_args(
 	struct xfs_da_args	*args)
 {
 	struct xfs_inode	*dp = args->dp;
-	struct xfs_da_state     *state;
-	int			error;
+	struct xfs_da_state     *state = NULL;
+	int			error = 0;
 
 	/*
 	 * If the attribute list is already in leaf format, jump straight to
@@ -342,7 +343,75 @@ xfs_attr_set_args(
 			return error;
 		error = xfs_attr_node_addname(args, state);
 	} while (error == -EAGAIN);
+	if (error)
+		return error;
 
+	/*
+	 * 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;
+
+	/*
+	 * 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) {
+		error = xfs_attr_rmtval_set(args);
+		if (error)
+			return error;
+	}
+
+	if (!(args->op_flags & XFS_DA_OP_RENAME)) {
+		/*
+		 * Added a "remote" value, just clear the incomplete flag.
+		 */
+		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.
+	 */
+	error = xfs_attr3_leaf_flipflags(args);
+	if (error)
+		goto out;
+	/*
+	 * 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;
+
+	/*
+	 * Dismantle the "old" attribute/value pair by removing a "remote" value
+	 * (if it exists).
+	 */
+	xfs_attr_restore_rmt_blk(args);
+
+	if (args->rmtblkno) {
+		error = xfs_attr_rmtval_invalidate(args);
+		if (error)
+			return error;
+
+		error = xfs_attr_rmtval_remove(args);
+		if (error)
+			return error;
+	}
+
+	error = xfs_attr_node_addname_clear_incomplete(args);
+out:
 	return error;
 }
 
@@ -968,7 +1037,7 @@ xfs_attr_node_addname(
 {
 	struct xfs_da_state_blk	*blk;
 	struct xfs_inode	*dp;
-	int			retval, error;
+	int			error;
 
 	trace_xfs_attr_node_addname(args);
 
@@ -976,8 +1045,8 @@ xfs_attr_node_addname(
 	blk = &state->path.blk[state->path.active-1];
 	ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
 
-	retval = xfs_attr3_leaf_add(blk->bp, state->args);
-	if (retval == -ENOSPC) {
+	error = xfs_attr3_leaf_add(blk->bp, state->args);
+	if (error == -ENOSPC) {
 		if (state->path.active == 1) {
 			/*
 			 * Its really a single leaf node, but it had
@@ -1023,88 +1092,10 @@ xfs_attr_node_addname(
 		xfs_da3_fixhashpath(state, &state->path);
 	}
 
-	/*
-	 * Kill the state structure, we're done with it and need to
-	 * allow the buffers to come back later.
-	 */
-	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;
-
-	/*
-	 * 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) {
-		error = xfs_attr_rmtval_set(args);
-		if (error)
-			return error;
-	}
-
-	if (!(args->op_flags & XFS_DA_OP_RENAME)) {
-		/*
-		 * Added a "remote" value, just clear the incomplete flag.
-		 */
-		if (args->rmtblkno > 0)
-			error = xfs_attr3_leaf_clearflag(args);
-		retval = error;
-		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.
-	 */
-	error = xfs_attr3_leaf_flipflags(args);
-	if (error)
-		goto out;
-	/*
-	 * 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;
-
-	/*
-	 * Dismantle the "old" attribute/value pair by removing a "remote" value
-	 * (if it exists).
-	 */
-	xfs_attr_restore_rmt_blk(args);
-
-	if (args->rmtblkno) {
-		error = xfs_attr_rmtval_invalidate(args);
-		if (error)
-			return error;
-
-		error = xfs_attr_rmtval_remove(args);
-		if (error)
-			return error;
-	}
-
-	error = xfs_attr_node_addname_clear_incomplete(args);
-	if (error)
-		goto out;
-	retval = 0;
 out:
 	if (state)
 		xfs_da_state_free(state);
-	if (error)
-		return error;
-	return retval;
+	return error;
 }
 
 
-- 
2.7.4

[PATCH RESEND v18 08/11] xfs: Hoist xfs_attr_leaf_addname

[Allison Henderson]

This patch hoists xfs_attr_leaf_addname into the calling function.  The
goal being to get all the code that will require state management into
the same scope. This isn't particularly aesthetic right away, but it is a
preliminary step to merging in the state machine code.

Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
---
 fs/xfs/libxfs/xfs_attr.c | 209 ++++++++++++++++++++++-------------------------
 fs/xfs/xfs_trace.h       |   1 -
 2 files changed, 96 insertions(+), 114 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index 3cc09e2..6edc3db 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -44,9 +44,9 @@ 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_removename(xfs_da_args_t *args);
 STATIC int xfs_attr_leaf_hasname(struct xfs_da_args *args, struct xfs_buf **bp);
+STATIC int xfs_attr_leaf_try_add(struct xfs_da_args *args, struct xfs_buf *bp);
 
 /*
  * Internal routines when attribute list is more than one block.
@@ -291,8 +291,9 @@ xfs_attr_set_args(
 	struct xfs_da_args	*args)
 {
 	struct xfs_inode	*dp = args->dp;
+	struct xfs_buf		*bp = NULL;
 	struct xfs_da_state     *state = NULL;
-	int			error = 0;
+	int			forkoff, error = 0;
 
 	/*
 	 * If the attribute list is already in leaf format, jump straight to
@@ -307,10 +308,101 @@ xfs_attr_set_args(
 	}
 
 	if (xfs_attr_is_leaf(dp)) {
-		error = xfs_attr_leaf_addname(args);
-		if (error != -ENOSPC)
+		error = xfs_attr_leaf_try_add(args, bp);
+		if (error == -ENOSPC)
+			goto node;
+		else if (error)
+			return error;
+
+		/*
+		 * 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;
+
+		/*
+		 * 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) {
+			error = xfs_attr_rmtval_set(args);
+			if (error)
+				return error;
+		}
+
+		if (!(args->op_flags & XFS_DA_OP_RENAME)) {
+			/*
+			 * Added a "remote" value, just clear the incomplete
+			 *flag.
+			 */
+			if (args->rmtblkno > 0)
+				error = xfs_attr3_leaf_clearflag(args);
+
+			return error;
+		}
+
+		/*
+		 * 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.
+		 */
+
+		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;
+
+		/*
+		 * Dismantle the "old" attribute/value pair by removing a
+		 * "remote" value (if it exists).
+		 */
+		xfs_attr_restore_rmt_blk(args);
+
+		if (args->rmtblkno) {
+			error = xfs_attr_rmtval_invalidate(args);
+			if (error)
+				return error;
+
+			error = xfs_attr_rmtval_remove(args);
+			if (error)
+				return error;
+		}
+
+		/*
+		 * Read in the block containing the "old" attr, then remove the
+		 * "old" attr from that block (neat, huh!)
+		 */
+		error = xfs_attr3_leaf_read(args->trans, args->dp, args->blkno,
+					   &bp);
+		if (error)
 			return error;
 
+		xfs_attr3_leaf_remove(bp, args);
+
+		/*
+		 * If the result is small enough, shrink it all into the inode.
+		 */
+		forkoff = xfs_attr_shortform_allfit(bp, dp);
+		if (forkoff)
+			error = xfs_attr3_leaf_to_shortform(bp, args, forkoff);
+			/* bp is gone due to xfs_da_shrink_inode */
+
+		return error;
+node:
 		/*
 		 * Promote the attribute list to the Btree format.
 		 */
@@ -737,115 +829,6 @@ xfs_attr_leaf_try_add(
 	return retval;
 }
 
-
-/*
- * Add a name to the leaf attribute list structure
- *
- * 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).
- */
-STATIC int
-xfs_attr_leaf_addname(
-	struct xfs_da_args	*args)
-{
-	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;
-
-	/*
-	 * 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;
-
-	/*
-	 * 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) {
-		error = xfs_attr_rmtval_set(args);
-		if (error)
-			return error;
-	}
-
-	if (!(args->op_flags & XFS_DA_OP_RENAME)) {
-		/*
-		 * Added a "remote" value, just clear the incomplete flag.
-		 */
-		if (args->rmtblkno > 0)
-			error = xfs_attr3_leaf_clearflag(args);
-
-		return error;
-	}
-
-	/*
-	 * 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.
-	 */
-
-	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;
-
-	/*
-	 * Dismantle the "old" attribute/value pair by removing a "remote" value
-	 * (if it exists).
-	 */
-	xfs_attr_restore_rmt_blk(args);
-
-	if (args->rmtblkno) {
-		error = xfs_attr_rmtval_invalidate(args);
-		if (error)
-			return error;
-
-		error = xfs_attr_rmtval_remove(args);
-		if (error)
-			return error;
-	}
-
-	/*
-	 * Read in the block containing the "old" attr, then remove the "old"
-	 * attr from that block (neat, huh!)
-	 */
-	error = xfs_attr3_leaf_read(args->trans, args->dp, args->blkno,
-				   &bp);
-	if (error)
-		return error;
-
-	xfs_attr3_leaf_remove(bp, args);
-
-	/*
-	 * If the result is small enough, shrink it all into the inode.
-	 */
-	forkoff = xfs_attr_shortform_allfit(bp, dp);
-	if (forkoff)
-		error = xfs_attr3_leaf_to_shortform(bp, args, forkoff);
-		/* bp is gone due to xfs_da_shrink_inode */
-
-	return error;
-}
-
 /*
  * Return EEXIST if attr is found, or ENOATTR if not
  */
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 808ae33..3c1c830 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -1914,7 +1914,6 @@ DEFINE_ATTR_EVENT(xfs_attr_leaf_add);
 DEFINE_ATTR_EVENT(xfs_attr_leaf_add_old);
 DEFINE_ATTR_EVENT(xfs_attr_leaf_add_new);
 DEFINE_ATTR_EVENT(xfs_attr_leaf_add_work);
-DEFINE_ATTR_EVENT(xfs_attr_leaf_addname);
 DEFINE_ATTR_EVENT(xfs_attr_leaf_create);
 DEFINE_ATTR_EVENT(xfs_attr_leaf_compact);
 DEFINE_ATTR_EVENT(xfs_attr_leaf_get);
-- 
2.7.4

[PATCH RESEND v18 09/11] xfs: Hoist node transaction handling

[Allison Henderson]

This patch basically hoists the node transaction handling around the
leaf code we just hoisted.  This will helps setup this area for the
state machine since the goto is easily replaced with a state since it
ends with a transaction roll.

Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
---
 fs/xfs/libxfs/xfs_attr.c | 55 +++++++++++++++++++++++++-----------------------
 1 file changed, 29 insertions(+), 26 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index 6edc3db..21f862e 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -309,10 +309,36 @@ xfs_attr_set_args(
 
 	if (xfs_attr_is_leaf(dp)) {
 		error = xfs_attr_leaf_try_add(args, bp);
-		if (error == -ENOSPC)
+		if (error == -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)
+				return error;
+
+			/*
+			 * Commit the current trans (including the inode) and
+			 * start a new one.
+			 */
+			error = xfs_trans_roll_inode(&args->trans, dp);
+			if (error)
+				return error;
+
 			goto node;
-		else if (error)
+		} else if (error) {
 			return error;
+		}
 
 		/*
 		 * Commit the transaction that added the attr name so that
@@ -402,32 +428,9 @@ xfs_attr_set_args(
 			/* bp is gone due to xfs_da_shrink_inode */
 
 		return error;
+	}
 node:
-		/*
-		 * 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)
-			return error;
 
-		/*
-		 * Commit the current trans (including the inode) and
-		 * start a new one.
-		 */
-		error = xfs_trans_roll_inode(&args->trans, dp);
-		if (error)
-			return error;
-	}
 
 	do {
 		error = xfs_attr_node_addname_find_attr(args, &state);
-- 
2.7.4

[PATCH RESEND v18 10/11] xfs: Add delay ready attr remove routines

[Allison Henderson]

This patch modifies the attr remove 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_remove_args is merged with
xfs_attr_node_removename become a new function, xfs_attr_remove_iter.
This new version uses a sort of state machine like switch to keep track
of where it was when EAGAIN was returned. A new version of
xfs_attr_remove_args consists of a simple loop to refresh the
transaction until the operation is completed. A new XFS_DAC_DEFER_FINISH
flag is used to finish the transaction where ever the existing code used
to.

Calls to xfs_attr_rmtval_remove are replaced with the delay ready
version __xfs_attr_rmtval_remove. We will rename
__xfs_attr_rmtval_remove back to xfs_attr_rmtval_remove when we are
done.

xfs_attr_rmtval_remove itself is still in use by the set routines (used
during a rename).  For reasons of preserving existing function, we
modify xfs_attr_rmtval_remove to call xfs_defer_finish when the flag is
set.  Similar to how xfs_attr_remove_args does here.  Once we transition
the set routines to be delay ready, xfs_attr_rmtval_remove is no longer
used and will be removed.

This patch also adds a new struct xfs_delattr_context, which we will use
to keep track of the current state of an attribute operation. The new
xfs_delattr_state enum is used to track various operations that are in
progress so that we know not to repeat them, and resume where we left
off before EAGAIN was returned to cycle out the transaction. Other
members take the place of local variables that need to retain their
values across multiple function recalls.  See xfs_attr.h for a more
detailed diagram of the states.

Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
---
 fs/xfs/libxfs/xfs_attr.c        | 213 ++++++++++++++++++++++++++++------------
 fs/xfs/libxfs/xfs_attr.h        | 131 ++++++++++++++++++++++++
 fs/xfs/libxfs/xfs_attr_leaf.c   |   2 +-
 fs/xfs/libxfs/xfs_attr_remote.c |  48 +++++----
 fs/xfs/libxfs/xfs_attr_remote.h |   2 +-
 fs/xfs/xfs_attr_inactive.c      |   2 +-
 6 files changed, 314 insertions(+), 84 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index 21f862e..a91fff6 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -57,7 +57,6 @@ STATIC int xfs_attr_node_addname(struct xfs_da_args *args,
 				 struct xfs_da_state *state);
 STATIC int xfs_attr_node_addname_find_attr(struct xfs_da_args *args,
 				 struct xfs_da_state **state);
-STATIC int xfs_attr_node_removename(xfs_da_args_t *args);
 STATIC int xfs_attr_node_addname_clear_incomplete(struct xfs_da_args *args);
 STATIC int xfs_attr_node_hasname(xfs_da_args_t *args,
 				 struct xfs_da_state **state);
@@ -241,6 +240,31 @@ xfs_attr_is_shortform(
 		ip->i_afp->if_nextents == 0);
 }
 
+/*
+ * Checks to see if a delayed attribute transaction should be rolled.  If so,
+ * transaction is finished or rolled as needed.
+ */
+int
+xfs_attr_trans_roll(
+	struct xfs_delattr_context	*dac)
+{
+	struct xfs_da_args		*args = dac->da_args;
+	int				error;
+
+	if (dac->flags & XFS_DAC_DEFER_FINISH) {
+		/*
+		 * The caller wants us to finish all the deferred ops so that we
+		 * avoid pinning the log tail with a large number of deferred
+		 * ops.
+		 */
+		dac->flags &= ~XFS_DAC_DEFER_FINISH;
+		error = xfs_defer_finish(&args->trans);
+	} else
+		error = xfs_trans_roll_inode(&args->trans, args->dp);
+
+	return error;
+}
+
 STATIC int
 xfs_attr_set_fmt(
 	struct xfs_da_args	*args)
@@ -544,16 +568,25 @@ xfs_has_attr(
  */
 int
 xfs_attr_remove_args(
-	struct xfs_da_args      *args)
+	struct xfs_da_args	*args)
 {
-	if (!xfs_inode_hasattr(args->dp))
-		return -ENOATTR;
+	int				error;
+	struct xfs_delattr_context	dac = {
+		.da_args	= args,
+	};
 
-	if (args->dp->i_afp->if_format == XFS_DINODE_FMT_LOCAL)
-		return xfs_attr_shortform_remove(args);
-	if (xfs_attr_is_leaf(args->dp))
-		return xfs_attr_leaf_removename(args);
-	return xfs_attr_node_removename(args);
+	do {
+		error = xfs_attr_remove_iter(&dac);
+		if (error != -EAGAIN)
+			break;
+
+		error = xfs_attr_trans_roll(&dac);
+		if (error)
+			return error;
+
+	} while (true);
+
+	return error;
 }
 
 /*
@@ -1197,14 +1230,16 @@ xfs_attr_leaf_mark_incomplete(
  */
 STATIC
 int xfs_attr_node_removename_setup(
-	struct xfs_da_args	*args,
-	struct xfs_da_state	**state)
+	struct xfs_delattr_context	*dac)
 {
-	int			error;
+	struct xfs_da_args		*args = dac->da_args;
+	struct xfs_da_state		**state = &dac->da_state;
+	int				error;
 
 	error = xfs_attr_node_hasname(args, state);
 	if (error != -EEXIST)
 		return error;
+	error = 0;
 
 	ASSERT((*state)->path.blk[(*state)->path.active - 1].bp != NULL);
 	ASSERT((*state)->path.blk[(*state)->path.active - 1].magic ==
@@ -1213,12 +1248,15 @@ int xfs_attr_node_removename_setup(
 	if (args->rmtblkno > 0) {
 		error = xfs_attr_leaf_mark_incomplete(args, *state);
 		if (error)
-			return error;
+			goto out;
 
-		return xfs_attr_rmtval_invalidate(args);
+		error = xfs_attr_rmtval_invalidate(args);
 	}
+out:
+	if (error)
+		xfs_da_state_free(*state);
 
-	return 0;
+	return error;
 }
 
 STATIC int
@@ -1241,70 +1279,123 @@ xfs_attr_node_remove_name(
 }
 
 /*
- * Remove a name from a B-tree attribute list.
+ * Remove the attribute specified in @args.
  *
  * This will involve walking down the Btree, and may involve joining
  * leaf nodes and even joining intermediate nodes up to and including
  * the root node (a special case of an intermediate node).
+ *
+ * This routine is meant to function as either an in-line or 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_removename(
-	struct xfs_da_args	*args)
+int
+xfs_attr_remove_iter(
+	struct xfs_delattr_context	*dac)
 {
-	struct xfs_da_state	*state;
-	int			retval, error;
-	struct xfs_inode	*dp = args->dp;
+	struct xfs_da_args		*args = dac->da_args;
+	struct xfs_da_state		*state = dac->da_state;
+	int				retval, error;
+	struct xfs_inode		*dp = args->dp;
 
 	trace_xfs_attr_node_removename(args);
 
-	error = xfs_attr_node_removename_setup(args, &state);
-	if (error)
-		goto out;
+	switch (dac->dela_state) {
+	case XFS_DAS_UNINIT:
+		if (!xfs_inode_hasattr(dp))
+			return -ENOATTR;
 
-	/*
-	 * If there is an out-of-line value, de-allocate the blocks.
-	 * This is done before we remove 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_remove(args);
-		if (error)
-			goto out;
+		/*
+		 * Shortform or leaf formats don't require transaction rolls and
+		 * thus state transitions. Call the right helper and return.
+		 */
+		if (dp->i_afp->if_format == XFS_DINODE_FMT_LOCAL)
+			return xfs_attr_shortform_remove(args);
+
+		if (xfs_attr_is_leaf(dp))
+			return xfs_attr_leaf_removename(args);
 
 		/*
-		 * Refill the state structure with buffers, the prior calls
-		 * released our buffers.
+		 * Node format may require transaction rolls. Set up the
+		 * state context and fall into the state machine.
 		 */
-		error = xfs_attr_refillstate(state);
-		if (error)
-			goto out;
-	}
-	retval = xfs_attr_node_remove_name(args, state);
+		if (!dac->da_state) {
+			error = xfs_attr_node_removename_setup(dac);
+			if (error)
+				return error;
+			state = dac->da_state;
+		}
+
+		/* fallthrough */
+	case XFS_DAS_RMTBLK:
+		dac->dela_state = XFS_DAS_RMTBLK;
 
-	/*
-	 * Check to see if the tree needs to be collapsed.
-	 */
-	if (retval && (state->path.active > 1)) {
-		error = xfs_da3_join(state);
-		if (error)
-			goto out;
-		error = xfs_defer_finish(&args->trans);
-		if (error)
-			goto out;
 		/*
-		 * Commit the Btree join operation and start a new trans.
+		 * If there is an out-of-line value, de-allocate the blocks.
+		 * This is done before we remove the attribute so that we don't
+		 * overflow the maximum size of a transaction and/or hit a
+		 * deadlock.
 		 */
-		error = xfs_trans_roll_inode(&args->trans, dp);
-		if (error)
-			goto out;
-	}
+		if (args->rmtblkno > 0) {
+			/*
+			 * May return -EAGAIN. Roll and repeat until all remote
+			 * blocks are removed.
+			 */
+			error = __xfs_attr_rmtval_remove(dac);
+			if (error == -EAGAIN)
+				return error;
+			else if (error)
+				goto out;
 
-	/*
-	 * If the result is small enough, push it all into the inode.
-	 */
-	if (xfs_attr_is_leaf(dp))
-		error = xfs_attr_node_shrink(args, state);
+			/*
+			 * Refill the state structure with buffers (the prior
+			 * calls released our buffers) and close out this
+			 * transaction before proceeding.
+			 */
+			ASSERT(args->rmtblkno == 0);
+			error = xfs_attr_refillstate(state);
+			if (error)
+				goto out;
+			dac->dela_state = XFS_DAS_RM_NAME;
+			dac->flags |= XFS_DAC_DEFER_FINISH;
+			return -EAGAIN;
+		}
+
+		/* fallthrough */
+	case XFS_DAS_RM_NAME:
+		retval = xfs_attr_node_remove_name(args, state);
 
+		/*
+		 * Check to see if the tree needs to be collapsed. If so, roll
+		 * the transacton and fall into the shrink state.
+		 */
+		if (retval && (state->path.active > 1)) {
+			error = xfs_da3_join(state);
+			if (error)
+				goto out;
+
+			dac->flags |= XFS_DAC_DEFER_FINISH;
+			dac->dela_state = XFS_DAS_RM_SHRINK;
+			return -EAGAIN;
+		}
+
+		/* fallthrough */
+	case XFS_DAS_RM_SHRINK:
+		/*
+		 * If the result is small enough, push it all into the inode.
+		 * This is our final state so it's safe to return a dirty
+		 * transaction.
+		 */
+		if (xfs_attr_is_leaf(dp))
+			error = xfs_attr_node_shrink(args, state);
+		ASSERT(error != -EAGAIN);
+		break;
+	default:
+		ASSERT(0);
+		error = -EINVAL;
+		goto out;
+	}
 out:
 	if (state)
 		xfs_da_state_free(state);
diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
index 2b1f619..32736d9 100644
--- a/fs/xfs/libxfs/xfs_attr.h
+++ b/fs/xfs/libxfs/xfs_attr.h
@@ -74,6 +74,133 @@ struct xfs_attr_list_context {
 };
 
 
+/*
+ * ========================================================================
+ * Structure used to pass context around among the delayed routines.
+ * ========================================================================
+ */
+
+/*
+ * Below is a state machine diagram for attr remove operations. The  XFS_DAS_*
+ * states indicate places where the function would return -EAGAIN, and then
+ * immediately resume from after being recalled by the calling function. States
+ * marked as a "subroutine state" indicate that they belong to a subroutine, and
+ * so the calling function needs to pass them back to that subroutine to allow
+ * it to finish where it left off. But they otherwise do not have a role in the
+ * calling function other than just passing through.
+ *
+ * xfs_attr_remove_iter()
+ *              │
+ *              v
+ *        have attr to remove? ──n──> done
+ *              │
+ *              y
+ *              │
+ *              v
+ *        are we short form? ──y──> xfs_attr_shortform_remove ──> done
+ *              │
+ *              n
+ *              │
+ *              V
+ *        are we leaf form? ──y──> xfs_attr_leaf_removename ──> done
+ *              │
+ *              n
+ *              │
+ *              V
+ *   ┌── need to setup state?
+ *   │          │
+ *   n          y
+ *   │          │
+ *   │          v
+ *   │ find attr and get state
+ *   │    attr has blks? ───n────┐
+ *   │          │                v
+ *   │          │         find and invalidate
+ *   │          y         the blocks. mark
+ *   │          │         attr incomplete
+ *   │          ├────────────────┘
+ *   └──────────┤
+ *              │
+ *              v
+ *      Have blks to remove? ───y─────────┐
+ *              │        ^          remove the blks
+ *              │        │                │
+ *              │        │                v
+ *              │  XFS_DAS_RMTBLK <─n── done?
+ *              │  re-enter with          │
+ *              │  one less blk to        y
+ *              │      remove             │
+ *              │                         V
+ *              │                  refill the state
+ *              n                         │
+ *              │                         v
+ *              │                   XFS_DAS_RM_NAME
+ *              │                         │
+ *              ├─────────────────────────┘
+ *              │
+ *              v
+ *       remove leaf and
+ *       update hash with
+ *   xfs_attr_node_remove_cleanup
+ *              │
+ *              v
+ *           need to
+ *        shrink tree? ─n─┐
+ *              │         │
+ *              y         │
+ *              │         │
+ *              v         │
+ *          join leaf     │
+ *              │         │
+ *              v         │
+ *      XFS_DAS_RM_SHRINK │
+ *              │         │
+ *              v         │
+ *       do the shrink    │
+ *              │         │
+ *              v         │
+ *          free state <──┘
+ *              │
+ *              v
+ *            done
+ *
+ */
+
+/*
+ * Enum values for xfs_delattr_context.da_state
+ *
+ * These values are used by delayed attribute operations to keep track  of where
+ * they were before they returned -EAGAIN.  A return code of -EAGAIN signals the
+ * calling function to roll the transaction, and then recall the subroutine to
+ * finish the operation.  The enum is then used by the subroutine to jump back
+ * to where it was and resume executing where it left off.
+ */
+enum xfs_delattr_state {
+	XFS_DAS_UNINIT		= 0,  /* No state has been set yet */
+	XFS_DAS_RMTBLK,		      /* Removing remote blks */
+	XFS_DAS_RM_NAME,	      /* Remove attr name */
+	XFS_DAS_RM_SHRINK,	      /* We are shrinking the tree */
+};
+
+/*
+ * Defines for xfs_delattr_context.flags
+ */
+#define XFS_DAC_DEFER_FINISH		0x01 /* finish the transaction */
+
+/*
+ * Context used for keeping track of delayed attribute operations
+ */
+struct xfs_delattr_context {
+	struct xfs_da_args      *da_args;
+
+	/* Used in xfs_attr_node_removename to roll through removing blocks */
+	struct xfs_da_state     *da_state;
+
+	/* Used to keep track of current state of delayed operation */
+	unsigned int            flags;
+	enum xfs_delattr_state  dela_state;
+};
+
 /*========================================================================
  * Function prototypes for the kernel.
  *========================================================================*/
@@ -92,6 +219,10 @@ int xfs_attr_set(struct xfs_da_args *args);
 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);
 
 #endif	/* __XFS_ATTR_H__ */
diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
index 556184b..d97de20 100644
--- a/fs/xfs/libxfs/xfs_attr_leaf.c
+++ b/fs/xfs/libxfs/xfs_attr_leaf.c
@@ -19,8 +19,8 @@
 #include "xfs_bmap_btree.h"
 #include "xfs_bmap.h"
 #include "xfs_attr_sf.h"
-#include "xfs_attr_remote.h"
 #include "xfs_attr.h"
+#include "xfs_attr_remote.h"
 #include "xfs_attr_leaf.h"
 #include "xfs_error.h"
 #include "xfs_trace.h"
diff --git a/fs/xfs/libxfs/xfs_attr_remote.c b/fs/xfs/libxfs/xfs_attr_remote.c
index 48d8e9c..2f3c4cc 100644
--- a/fs/xfs/libxfs/xfs_attr_remote.c
+++ b/fs/xfs/libxfs/xfs_attr_remote.c
@@ -674,10 +674,12 @@ xfs_attr_rmtval_invalidate(
  */
 int
 xfs_attr_rmtval_remove(
-	struct xfs_da_args      *args)
+	struct xfs_da_args		*args)
 {
-	int			error;
-	int			retval;
+	int				error;
+	struct xfs_delattr_context	dac  = {
+		.da_args	= args,
+	};
 
 	trace_xfs_attr_rmtval_remove(args);
 
@@ -685,31 +687,29 @@ xfs_attr_rmtval_remove(
 	 * Keep de-allocating extents until the remote-value region is gone.
 	 */
 	do {
-		retval = __xfs_attr_rmtval_remove(args);
-		if (retval && retval != -EAGAIN)
-			return retval;
+		error = __xfs_attr_rmtval_remove(&dac);
+		if (error && error != -EAGAIN)
+			break;
 
-		/*
-		 * Close out trans and start the next one in the chain.
-		 */
-		error = xfs_trans_roll_inode(&args->trans, args->dp);
+		error = xfs_attr_trans_roll(&dac);
 		if (error)
 			return error;
-	} while (retval == -EAGAIN);
+	} while (true);
 
-	return 0;
+	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
+ * buffer that it is stored on. Returns -EAGAIN for the caller to refresh the
  * transaction and re-call the function
  */
 int
 __xfs_attr_rmtval_remove(
-	struct xfs_da_args	*args)
+	struct xfs_delattr_context	*dac)
 {
-	int			error, done;
+	struct xfs_da_args		*args = dac->da_args;
+	int				error, done;
 
 	/*
 	 * Unmap value blocks for this attr.
@@ -719,12 +719,20 @@ __xfs_attr_rmtval_remove(
 	if (error)
 		return error;
 
-	error = xfs_defer_finish(&args->trans);
-	if (error)
-		return error;
-
-	if (!done)
+	/*
+	 * We don't need an explicit state here to pick up where we left off. We
+	 * can figure it out using the !done return code. Calling function only
+	 * needs to keep recalling this routine until we indicate to stop by
+	 * returning anything other than -EAGAIN. The actual value of
+	 * attr->xattri_dela_state may be some value reminiscent of the calling
+	 * function, but it's value is irrelevant with in the context of this
+	 * function. Once we are done here, the next state is set as needed
+	 * by the parent
+	 */
+	if (!done) {
+		dac->flags |= XFS_DAC_DEFER_FINISH;
 		return -EAGAIN;
+	}
 
 	return error;
 }
diff --git a/fs/xfs/libxfs/xfs_attr_remote.h b/fs/xfs/libxfs/xfs_attr_remote.h
index 9eee615..002fd30 100644
--- a/fs/xfs/libxfs/xfs_attr_remote.h
+++ b/fs/xfs/libxfs/xfs_attr_remote.h
@@ -14,5 +14,5 @@ int xfs_attr_rmtval_remove(struct xfs_da_args *args);
 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_da_args *args);
+int __xfs_attr_rmtval_remove(struct xfs_delattr_context *dac);
 #endif /* __XFS_ATTR_REMOTE_H__ */
diff --git a/fs/xfs/xfs_attr_inactive.c b/fs/xfs/xfs_attr_inactive.c
index bfad669..aaa7e66 100644
--- a/fs/xfs/xfs_attr_inactive.c
+++ b/fs/xfs/xfs_attr_inactive.c
@@ -15,10 +15,10 @@
 #include "xfs_da_format.h"
 #include "xfs_da_btree.h"
 #include "xfs_inode.h"
+#include "xfs_attr.h"
 #include "xfs_attr_remote.h"
 #include "xfs_trans.h"
 #include "xfs_bmap.h"
-#include "xfs_attr.h"
 #include "xfs_attr_leaf.h"
 #include "xfs_quota.h"
 #include "xfs_dir2.h"
-- 
2.7.4

Re: [PATCH RESEND v18 10/11] xfs: Add delay ready attr remove routines

[Darrick J. Wong]

On Wed, May 12, 2021 at 09:14:07AM -0700, Allison Henderson wrote:
> This patch modifies the attr remove 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_remove_args is merged with
> xfs_attr_node_removename become a new function, xfs_attr_remove_iter.
> This new version uses a sort of state machine like switch to keep track
> of where it was when EAGAIN was returned. A new version of
> xfs_attr_remove_args consists of a simple loop to refresh the
> transaction until the operation is completed. A new XFS_DAC_DEFER_FINISH
> flag is used to finish the transaction where ever the existing code used
> to.
> 
> Calls to xfs_attr_rmtval_remove are replaced with the delay ready
> version __xfs_attr_rmtval_remove. We will rename
> __xfs_attr_rmtval_remove back to xfs_attr_rmtval_remove when we are
> done.
> 
> xfs_attr_rmtval_remove itself is still in use by the set routines (used
> during a rename).  For reasons of preserving existing function, we
> modify xfs_attr_rmtval_remove to call xfs_defer_finish when the flag is
> set.  Similar to how xfs_attr_remove_args does here.  Once we transition
> the set routines to be delay ready, xfs_attr_rmtval_remove is no longer
> used and will be removed.
> 
> This patch also adds a new struct xfs_delattr_context, which we will use
> to keep track of the current state of an attribute operation. The new
> xfs_delattr_state enum is used to track various operations that are in
> progress so that we know not to repeat them, and resume where we left
> off before EAGAIN was returned to cycle out the transaction. Other
> members take the place of local variables that need to retain their
> values across multiple function recalls.  See xfs_attr.h for a more
> detailed diagram of the states.
> 
> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
> Reviewed-by: Brian Foster <bfoster@redhat.com>
> ---
>  fs/xfs/libxfs/xfs_attr.c        | 213 ++++++++++++++++++++++++++++------------
>  fs/xfs/libxfs/xfs_attr.h        | 131 ++++++++++++++++++++++++
>  fs/xfs/libxfs/xfs_attr_leaf.c   |   2 +-
>  fs/xfs/libxfs/xfs_attr_remote.c |  48 +++++----
>  fs/xfs/libxfs/xfs_attr_remote.h |   2 +-
>  fs/xfs/xfs_attr_inactive.c      |   2 +-
>  6 files changed, 314 insertions(+), 84 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index 21f862e..a91fff6 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
> @@ -57,7 +57,6 @@ STATIC int xfs_attr_node_addname(struct xfs_da_args *args,
>  				 struct xfs_da_state *state);
>  STATIC int xfs_attr_node_addname_find_attr(struct xfs_da_args *args,
>  				 struct xfs_da_state **state);
> -STATIC int xfs_attr_node_removename(xfs_da_args_t *args);
>  STATIC int xfs_attr_node_addname_clear_incomplete(struct xfs_da_args *args);
>  STATIC int xfs_attr_node_hasname(xfs_da_args_t *args,
>  				 struct xfs_da_state **state);
> @@ -241,6 +240,31 @@ xfs_attr_is_shortform(
>  		ip->i_afp->if_nextents == 0);
>  }
>  
> +/*
> + * Checks to see if a delayed attribute transaction should be rolled.  If so,
> + * transaction is finished or rolled as needed.
> + */
> +int
> +xfs_attr_trans_roll(
> +	struct xfs_delattr_context	*dac)
> +{
> +	struct xfs_da_args		*args = dac->da_args;
> +	int				error;
> +
> +	if (dac->flags & XFS_DAC_DEFER_FINISH) {
> +		/*
> +		 * The caller wants us to finish all the deferred ops so that we
> +		 * avoid pinning the log tail with a large number of deferred
> +		 * ops.
> +		 */
> +		dac->flags &= ~XFS_DAC_DEFER_FINISH;
> +		error = xfs_defer_finish(&args->trans);
> +	} else
> +		error = xfs_trans_roll_inode(&args->trans, args->dp);
> +
> +	return error;
> +}
> +
>  STATIC int
>  xfs_attr_set_fmt(
>  	struct xfs_da_args	*args)
> @@ -544,16 +568,25 @@ xfs_has_attr(
>   */
>  int
>  xfs_attr_remove_args(
> -	struct xfs_da_args      *args)
> +	struct xfs_da_args	*args)
>  {
> -	if (!xfs_inode_hasattr(args->dp))
> -		return -ENOATTR;
> +	int				error;
> +	struct xfs_delattr_context	dac = {
> +		.da_args	= args,
> +	};
>  
> -	if (args->dp->i_afp->if_format == XFS_DINODE_FMT_LOCAL)
> -		return xfs_attr_shortform_remove(args);
> -	if (xfs_attr_is_leaf(args->dp))
> -		return xfs_attr_leaf_removename(args);
> -	return xfs_attr_node_removename(args);
> +	do {
> +		error = xfs_attr_remove_iter(&dac);
> +		if (error != -EAGAIN)
> +			break;
> +
> +		error = xfs_attr_trans_roll(&dac);
> +		if (error)
> +			return error;
> +
> +	} while (true);
> +
> +	return error;
>  }
>  
>  /*
> @@ -1197,14 +1230,16 @@ xfs_attr_leaf_mark_incomplete(
>   */
>  STATIC
>  int xfs_attr_node_removename_setup(
> -	struct xfs_da_args	*args,
> -	struct xfs_da_state	**state)
> +	struct xfs_delattr_context	*dac)
>  {
> -	int			error;
> +	struct xfs_da_args		*args = dac->da_args;
> +	struct xfs_da_state		**state = &dac->da_state;
> +	int				error;
>  
>  	error = xfs_attr_node_hasname(args, state);
>  	if (error != -EEXIST)
>  		return error;
> +	error = 0;
>  
>  	ASSERT((*state)->path.blk[(*state)->path.active - 1].bp != NULL);
>  	ASSERT((*state)->path.blk[(*state)->path.active - 1].magic ==
> @@ -1213,12 +1248,15 @@ int xfs_attr_node_removename_setup(
>  	if (args->rmtblkno > 0) {
>  		error = xfs_attr_leaf_mark_incomplete(args, *state);
>  		if (error)
> -			return error;
> +			goto out;
>  
> -		return xfs_attr_rmtval_invalidate(args);
> +		error = xfs_attr_rmtval_invalidate(args);
>  	}
> +out:
> +	if (error)
> +		xfs_da_state_free(*state);
>  
> -	return 0;
> +	return error;
>  }
>  
>  STATIC int
> @@ -1241,70 +1279,123 @@ xfs_attr_node_remove_name(
>  }
>  
>  /*
> - * Remove a name from a B-tree attribute list.
> + * Remove the attribute specified in @args.
>   *
>   * This will involve walking down the Btree, and may involve joining
>   * leaf nodes and even joining intermediate nodes up to and including
>   * the root node (a special case of an intermediate node).
> + *
> + * This routine is meant to function as either an in-line or 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_removename(
> -	struct xfs_da_args	*args)
> +int
> +xfs_attr_remove_iter(
> +	struct xfs_delattr_context	*dac)
>  {
> -	struct xfs_da_state	*state;
> -	int			retval, error;
> -	struct xfs_inode	*dp = args->dp;
> +	struct xfs_da_args		*args = dac->da_args;
> +	struct xfs_da_state		*state = dac->da_state;
> +	int				retval, error;
> +	struct xfs_inode		*dp = args->dp;
>  
>  	trace_xfs_attr_node_removename(args);
>  
> -	error = xfs_attr_node_removename_setup(args, &state);
> -	if (error)
> -		goto out;
> +	switch (dac->dela_state) {
> +	case XFS_DAS_UNINIT:
> +		if (!xfs_inode_hasattr(dp))
> +			return -ENOATTR;
>  
> -	/*
> -	 * If there is an out-of-line value, de-allocate the blocks.
> -	 * This is done before we remove 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_remove(args);
> -		if (error)
> -			goto out;
> +		/*
> +		 * Shortform or leaf formats don't require transaction rolls and
> +		 * thus state transitions. Call the right helper and return.
> +		 */
> +		if (dp->i_afp->if_format == XFS_DINODE_FMT_LOCAL)
> +			return xfs_attr_shortform_remove(args);
> +
> +		if (xfs_attr_is_leaf(dp))
> +			return xfs_attr_leaf_removename(args);
>  
>  		/*
> -		 * Refill the state structure with buffers, the prior calls
> -		 * released our buffers.
> +		 * Node format may require transaction rolls. Set up the
> +		 * state context and fall into the state machine.
>  		 */
> -		error = xfs_attr_refillstate(state);
> -		if (error)
> -			goto out;
> -	}
> -	retval = xfs_attr_node_remove_name(args, state);
> +		if (!dac->da_state) {
> +			error = xfs_attr_node_removename_setup(dac);
> +			if (error)
> +				return error;
> +			state = dac->da_state;
> +		}
> +
> +		/* fallthrough */
> +	case XFS_DAS_RMTBLK:
> +		dac->dela_state = XFS_DAS_RMTBLK;
>  
> -	/*
> -	 * Check to see if the tree needs to be collapsed.
> -	 */
> -	if (retval && (state->path.active > 1)) {
> -		error = xfs_da3_join(state);
> -		if (error)
> -			goto out;
> -		error = xfs_defer_finish(&args->trans);
> -		if (error)
> -			goto out;
>  		/*
> -		 * Commit the Btree join operation and start a new trans.
> +		 * If there is an out-of-line value, de-allocate the blocks.
> +		 * This is done before we remove the attribute so that we don't
> +		 * overflow the maximum size of a transaction and/or hit a
> +		 * deadlock.
>  		 */
> -		error = xfs_trans_roll_inode(&args->trans, dp);
> -		if (error)
> -			goto out;
> -	}
> +		if (args->rmtblkno > 0) {
> +			/*
> +			 * May return -EAGAIN. Roll and repeat until all remote
> +			 * blocks are removed.
> +			 */
> +			error = __xfs_attr_rmtval_remove(dac);
> +			if (error == -EAGAIN)
> +				return error;
> +			else if (error)
> +				goto out;
>  
> -	/*
> -	 * If the result is small enough, push it all into the inode.
> -	 */
> -	if (xfs_attr_is_leaf(dp))
> -		error = xfs_attr_node_shrink(args, state);
> +			/*
> +			 * Refill the state structure with buffers (the prior
> +			 * calls released our buffers) and close out this
> +			 * transaction before proceeding.
> +			 */
> +			ASSERT(args->rmtblkno == 0);
> +			error = xfs_attr_refillstate(state);
> +			if (error)
> +				goto out;
> +			dac->dela_state = XFS_DAS_RM_NAME;
> +			dac->flags |= XFS_DAC_DEFER_FINISH;
> +			return -EAGAIN;
> +		}
> +
> +		/* fallthrough */
> +	case XFS_DAS_RM_NAME:
> +		retval = xfs_attr_node_remove_name(args, state);

Hm.  I see a bunch of cleanup possibilities for after this series...

xfs_attr_shortform_remove
xfs_attr_leaf_removename
xfs_attr_node_remove_name

Can you add a patch to the end of the series renaming these to
xfs_attr_{sf,leaf,node}_removename or something?

Also, can you refactor the chunk of code under "Remove the name and
update the hashvals in the tree" in
xfs_attr_node_addname_clear_incomplete to use xfs_attr_node_remove_name?

(Separate cleanup patches at the end of the series would be appreciated.)

>  
> +		/*
> +		 * Check to see if the tree needs to be collapsed. If so, roll
> +		 * the transacton and fall into the shrink state.
> +		 */
> +		if (retval && (state->path.active > 1)) {
> +			error = xfs_da3_join(state);
> +			if (error)
> +				goto out;
> +
> +			dac->flags |= XFS_DAC_DEFER_FINISH;
> +			dac->dela_state = XFS_DAS_RM_SHRINK;
> +			return -EAGAIN;
> +		}
> +
> +		/* fallthrough */
> +	case XFS_DAS_RM_SHRINK:
> +		/*
> +		 * If the result is small enough, push it all into the inode.
> +		 * This is our final state so it's safe to return a dirty
> +		 * transaction.
> +		 */
> +		if (xfs_attr_is_leaf(dp))
> +			error = xfs_attr_node_shrink(args, state);
> +		ASSERT(error != -EAGAIN);
> +		break;
> +	default:
> +		ASSERT(0);
> +		error = -EINVAL;
> +		goto out;
> +	}
>  out:
>  	if (state)
>  		xfs_da_state_free(state);
> diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
> index 2b1f619..32736d9 100644
> --- a/fs/xfs/libxfs/xfs_attr.h
> +++ b/fs/xfs/libxfs/xfs_attr.h
> @@ -74,6 +74,133 @@ struct xfs_attr_list_context {
>  };
>  
>  
> +/*
> + * ========================================================================
> + * Structure used to pass context around among the delayed routines.
> + * ========================================================================
> + */
> +
> +/*
> + * Below is a state machine diagram for attr remove operations. The  XFS_DAS_*
> + * states indicate places where the function would return -EAGAIN, and then
> + * immediately resume from after being recalled by the calling function. States
> + * marked as a "subroutine state" indicate that they belong to a subroutine, and
> + * so the calling function needs to pass them back to that subroutine to allow
> + * it to finish where it left off. But they otherwise do not have a role in the
> + * calling function other than just passing through.
> + *
> + * xfs_attr_remove_iter()
> + *              │
> + *              v
> + *        have attr to remove? ──n──> done
> + *              │
> + *              y
> + *              │
> + *              v
> + *        are we short form? ──y──> xfs_attr_shortform_remove ──> done
> + *              │
> + *              n
> + *              │
> + *              V
> + *        are we leaf form? ──y──> xfs_attr_leaf_removename ──> done
> + *              │
> + *              n
> + *              │
> + *              V
> + *   ┌── need to setup state?
> + *   │          │
> + *   n          y
> + *   │          │
> + *   │          v
> + *   │ find attr and get state
> + *   │    attr has blks? ───n────┐

Nit: This should be "attr has remote blks?" since everywhere else in the
code we call them remote value blocks.

> + *   │          │                v
> + *   │          │         find and invalidate
> + *   │          y         the blocks. mark

remote blocks...

> + *   │          │         attr incomplete
> + *   │          ├────────────────┘
> + *   └──────────┤
> + *              │
> + *              v
> + *      Have blks to remove? ───y─────────┐
> + *              │        ^          remove the blks

remote blocks...

> + *              │        │                │
> + *              │        │                v
> + *              │  XFS_DAS_RMTBLK <─n── done?
> + *              │  re-enter with          │
> + *              │  one less blk to        y
> + *              │      remove             │
> + *              │                         V
> + *              │                  refill the state
> + *              n                         │
> + *              │                         v
> + *              │                   XFS_DAS_RM_NAME
> + *              │                         │
> + *              ├─────────────────────────┘
> + *              │
> + *              v
> + *       remove leaf and
> + *       update hash with
> + *   xfs_attr_node_remove_cleanup
> + *              │
> + *              v
> + *           need to
> + *        shrink tree? ─n─┐
> + *              │         │
> + *              y         │
> + *              │         │
> + *              v         │
> + *          join leaf     │
> + *              │         │
> + *              v         │
> + *      XFS_DAS_RM_SHRINK │
> + *              │         │
> + *              v         │
> + *       do the shrink    │
> + *              │         │
> + *              v         │
> + *          free state <──┘
> + *              │
> + *              v
> + *            done
> + *
> + */
> +
> +/*
> + * Enum values for xfs_delattr_context.da_state
> + *
> + * These values are used by delayed attribute operations to keep track  of where
> + * they were before they returned -EAGAIN.  A return code of -EAGAIN signals the
> + * calling function to roll the transaction, and then recall the subroutine to

nit: s/recall/call the subroutine again/

> + * finish the operation.  The enum is then used by the subroutine to jump back
> + * to where it was and resume executing where it left off.
> + */
> +enum xfs_delattr_state {
> +	XFS_DAS_UNINIT		= 0,  /* No state has been set yet */
> +	XFS_DAS_RMTBLK,		      /* Removing remote blks */
> +	XFS_DAS_RM_NAME,	      /* Remove attr name */
> +	XFS_DAS_RM_SHRINK,	      /* We are shrinking the tree */
> +};
> +
> +/*
> + * Defines for xfs_delattr_context.flags
> + */
> +#define XFS_DAC_DEFER_FINISH		0x01 /* finish the transaction */
> +
> +/*
> + * Context used for keeping track of delayed attribute operations
> + */
> +struct xfs_delattr_context {
> +	struct xfs_da_args      *da_args;
> +
> +	/* Used in xfs_attr_node_removename to roll through removing blocks */
> +	struct xfs_da_state     *da_state;
> +
> +	/* Used to keep track of current state of delayed operation */
> +	unsigned int            flags;
> +	enum xfs_delattr_state  dela_state;
> +};
> +
>  /*========================================================================
>   * Function prototypes for the kernel.
>   *========================================================================*/
> @@ -92,6 +219,10 @@ int xfs_attr_set(struct xfs_da_args *args);
>  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);
>  
>  #endif	/* __XFS_ATTR_H__ */
> diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
> index 556184b..d97de20 100644
> --- a/fs/xfs/libxfs/xfs_attr_leaf.c
> +++ b/fs/xfs/libxfs/xfs_attr_leaf.c
> @@ -19,8 +19,8 @@
>  #include "xfs_bmap_btree.h"
>  #include "xfs_bmap.h"
>  #include "xfs_attr_sf.h"
> -#include "xfs_attr_remote.h"
>  #include "xfs_attr.h"
> +#include "xfs_attr_remote.h"
>  #include "xfs_attr_leaf.h"
>  #include "xfs_error.h"
>  #include "xfs_trace.h"
> diff --git a/fs/xfs/libxfs/xfs_attr_remote.c b/fs/xfs/libxfs/xfs_attr_remote.c
> index 48d8e9c..2f3c4cc 100644
> --- a/fs/xfs/libxfs/xfs_attr_remote.c
> +++ b/fs/xfs/libxfs/xfs_attr_remote.c
> @@ -674,10 +674,12 @@ xfs_attr_rmtval_invalidate(
>   */
>  int
>  xfs_attr_rmtval_remove(
> -	struct xfs_da_args      *args)
> +	struct xfs_da_args		*args)
>  {
> -	int			error;
> -	int			retval;
> +	int				error;
> +	struct xfs_delattr_context	dac  = {
> +		.da_args	= args,
> +	};
>  
>  	trace_xfs_attr_rmtval_remove(args);
>  
> @@ -685,31 +687,29 @@ xfs_attr_rmtval_remove(
>  	 * Keep de-allocating extents until the remote-value region is gone.
>  	 */
>  	do {
> -		retval = __xfs_attr_rmtval_remove(args);
> -		if (retval && retval != -EAGAIN)
> -			return retval;
> +		error = __xfs_attr_rmtval_remove(&dac);
> +		if (error && error != -EAGAIN)
> +			break;
>  
> -		/*
> -		 * Close out trans and start the next one in the chain.
> -		 */
> -		error = xfs_trans_roll_inode(&args->trans, args->dp);
> +		error = xfs_attr_trans_roll(&dac);
>  		if (error)
>  			return error;
> -	} while (retval == -EAGAIN);
> +	} while (true);
>  
> -	return 0;
> +	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
> + * buffer that it is stored on. Returns -EAGAIN for the caller to refresh the
>   * transaction and re-call the function
>   */
>  int
>  __xfs_attr_rmtval_remove(
> -	struct xfs_da_args	*args)
> +	struct xfs_delattr_context	*dac)
>  {
> -	int			error, done;
> +	struct xfs_da_args		*args = dac->da_args;
> +	int				error, done;
>  
>  	/*
>  	 * Unmap value blocks for this attr.
> @@ -719,12 +719,20 @@ __xfs_attr_rmtval_remove(
>  	if (error)
>  		return error;
>  
> -	error = xfs_defer_finish(&args->trans);
> -	if (error)
> -		return error;
> -
> -	if (!done)
> +	/*
> +	 * We don't need an explicit state here to pick up where we left off. We
> +	 * can figure it out using the !done return code. Calling function only
> +	 * needs to keep recalling this routine until we indicate to stop by

"Callers should keep calling this routine until it returns something
other than -EAGAIN."

Also, that should go in the comment above the function.

With all those fairly minor things fixed,
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> +	 * returning anything other than -EAGAIN. The actual value of
> +	 * attr->xattri_dela_state may be some value reminiscent of the calling
> +	 * function, but it's value is irrelevant with in the context of this
> +	 * function. Once we are done here, the next state is set as needed
> +	 * by the parent
> +	 */
> +	if (!done) {
> +		dac->flags |= XFS_DAC_DEFER_FINISH;
>  		return -EAGAIN;
> +	}
>  
>  	return error;
>  }
> diff --git a/fs/xfs/libxfs/xfs_attr_remote.h b/fs/xfs/libxfs/xfs_attr_remote.h
> index 9eee615..002fd30 100644
> --- a/fs/xfs/libxfs/xfs_attr_remote.h
> +++ b/fs/xfs/libxfs/xfs_attr_remote.h
> @@ -14,5 +14,5 @@ int xfs_attr_rmtval_remove(struct xfs_da_args *args);
>  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_da_args *args);
> +int __xfs_attr_rmtval_remove(struct xfs_delattr_context *dac);
>  #endif /* __XFS_ATTR_REMOTE_H__ */
> diff --git a/fs/xfs/xfs_attr_inactive.c b/fs/xfs/xfs_attr_inactive.c
> index bfad669..aaa7e66 100644
> --- a/fs/xfs/xfs_attr_inactive.c
> +++ b/fs/xfs/xfs_attr_inactive.c
> @@ -15,10 +15,10 @@
>  #include "xfs_da_format.h"
>  #include "xfs_da_btree.h"
>  #include "xfs_inode.h"
> +#include "xfs_attr.h"
>  #include "xfs_attr_remote.h"
>  #include "xfs_trans.h"
>  #include "xfs_bmap.h"
> -#include "xfs_attr.h"
>  #include "xfs_attr_leaf.h"
>  #include "xfs_quota.h"
>  #include "xfs_dir2.h"
> -- 
> 2.7.4
> 

Re: [PATCH RESEND v18 10/11] xfs: Add delay ready attr remove routines

[Allison Henderson]

On 5/13/21 5:46 PM, Darrick J. Wong wrote:
> On Wed, May 12, 2021 at 09:14:07AM -0700, Allison Henderson wrote:
>> This patch modifies the attr remove 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_remove_args is merged with
>> xfs_attr_node_removename become a new function, xfs_attr_remove_iter.
>> This new version uses a sort of state machine like switch to keep track
>> of where it was when EAGAIN was returned. A new version of
>> xfs_attr_remove_args consists of a simple loop to refresh the
>> transaction until the operation is completed. A new XFS_DAC_DEFER_FINISH
>> flag is used to finish the transaction where ever the existing code used
>> to.
>>
>> Calls to xfs_attr_rmtval_remove are replaced with the delay ready
>> version __xfs_attr_rmtval_remove. We will rename
>> __xfs_attr_rmtval_remove back to xfs_attr_rmtval_remove when we are
>> done.
>>
>> xfs_attr_rmtval_remove itself is still in use by the set routines (used
>> during a rename).  For reasons of preserving existing function, we
>> modify xfs_attr_rmtval_remove to call xfs_defer_finish when the flag is
>> set.  Similar to how xfs_attr_remove_args does here.  Once we transition
>> the set routines to be delay ready, xfs_attr_rmtval_remove is no longer
>> used and will be removed.
>>
>> This patch also adds a new struct xfs_delattr_context, which we will use
>> to keep track of the current state of an attribute operation. The new
>> xfs_delattr_state enum is used to track various operations that are in
>> progress so that we know not to repeat them, and resume where we left
>> off before EAGAIN was returned to cycle out the transaction. Other
>> members take the place of local variables that need to retain their
>> values across multiple function recalls.  See xfs_attr.h for a more
>> detailed diagram of the states.
>>
>> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
>> Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
>> Reviewed-by: Brian Foster <bfoster@redhat.com>
>> ---
>>   fs/xfs/libxfs/xfs_attr.c        | 213 ++++++++++++++++++++++++++++------------
>>   fs/xfs/libxfs/xfs_attr.h        | 131 ++++++++++++++++++++++++
>>   fs/xfs/libxfs/xfs_attr_leaf.c   |   2 +-
>>   fs/xfs/libxfs/xfs_attr_remote.c |  48 +++++----
>>   fs/xfs/libxfs/xfs_attr_remote.h |   2 +-
>>   fs/xfs/xfs_attr_inactive.c      |   2 +-
>>   6 files changed, 314 insertions(+), 84 deletions(-)
>>
>> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
>> index 21f862e..a91fff6 100644
>> --- a/fs/xfs/libxfs/xfs_attr.c
>> +++ b/fs/xfs/libxfs/xfs_attr.c
>> @@ -57,7 +57,6 @@ STATIC int xfs_attr_node_addname(struct xfs_da_args *args,
>>   				 struct xfs_da_state *state);
>>   STATIC int xfs_attr_node_addname_find_attr(struct xfs_da_args *args,
>>   				 struct xfs_da_state **state);
>> -STATIC int xfs_attr_node_removename(xfs_da_args_t *args);
>>   STATIC int xfs_attr_node_addname_clear_incomplete(struct xfs_da_args *args);
>>   STATIC int xfs_attr_node_hasname(xfs_da_args_t *args,
>>   				 struct xfs_da_state **state);
>> @@ -241,6 +240,31 @@ xfs_attr_is_shortform(
>>   		ip->i_afp->if_nextents == 0);
>>   }
>>   
>> +/*
>> + * Checks to see if a delayed attribute transaction should be rolled.  If so,
>> + * transaction is finished or rolled as needed.
>> + */
>> +int
>> +xfs_attr_trans_roll(
>> +	struct xfs_delattr_context	*dac)
>> +{
>> +	struct xfs_da_args		*args = dac->da_args;
>> +	int				error;
>> +
>> +	if (dac->flags & XFS_DAC_DEFER_FINISH) {
>> +		/*
>> +		 * The caller wants us to finish all the deferred ops so that we
>> +		 * avoid pinning the log tail with a large number of deferred
>> +		 * ops.
>> +		 */
>> +		dac->flags &= ~XFS_DAC_DEFER_FINISH;
>> +		error = xfs_defer_finish(&args->trans);
>> +	} else
>> +		error = xfs_trans_roll_inode(&args->trans, args->dp);
>> +
>> +	return error;
>> +}
>> +
>>   STATIC int
>>   xfs_attr_set_fmt(
>>   	struct xfs_da_args	*args)
>> @@ -544,16 +568,25 @@ xfs_has_attr(
>>    */
>>   int
>>   xfs_attr_remove_args(
>> -	struct xfs_da_args      *args)
>> +	struct xfs_da_args	*args)
>>   {
>> -	if (!xfs_inode_hasattr(args->dp))
>> -		return -ENOATTR;
>> +	int				error;
>> +	struct xfs_delattr_context	dac = {
>> +		.da_args	= args,
>> +	};
>>   
>> -	if (args->dp->i_afp->if_format == XFS_DINODE_FMT_LOCAL)
>> -		return xfs_attr_shortform_remove(args);
>> -	if (xfs_attr_is_leaf(args->dp))
>> -		return xfs_attr_leaf_removename(args);
>> -	return xfs_attr_node_removename(args);
>> +	do {
>> +		error = xfs_attr_remove_iter(&dac);
>> +		if (error != -EAGAIN)
>> +			break;
>> +
>> +		error = xfs_attr_trans_roll(&dac);
>> +		if (error)
>> +			return error;
>> +
>> +	} while (true);
>> +
>> +	return error;
>>   }
>>   
>>   /*
>> @@ -1197,14 +1230,16 @@ xfs_attr_leaf_mark_incomplete(
>>    */
>>   STATIC
>>   int xfs_attr_node_removename_setup(
>> -	struct xfs_da_args	*args,
>> -	struct xfs_da_state	**state)
>> +	struct xfs_delattr_context	*dac)
>>   {
>> -	int			error;
>> +	struct xfs_da_args		*args = dac->da_args;
>> +	struct xfs_da_state		**state = &dac->da_state;
>> +	int				error;
>>   
>>   	error = xfs_attr_node_hasname(args, state);
>>   	if (error != -EEXIST)
>>   		return error;
>> +	error = 0;
>>   
>>   	ASSERT((*state)->path.blk[(*state)->path.active - 1].bp != NULL);
>>   	ASSERT((*state)->path.blk[(*state)->path.active - 1].magic ==
>> @@ -1213,12 +1248,15 @@ int xfs_attr_node_removename_setup(
>>   	if (args->rmtblkno > 0) {
>>   		error = xfs_attr_leaf_mark_incomplete(args, *state);
>>   		if (error)
>> -			return error;
>> +			goto out;
>>   
>> -		return xfs_attr_rmtval_invalidate(args);
>> +		error = xfs_attr_rmtval_invalidate(args);
>>   	}
>> +out:
>> +	if (error)
>> +		xfs_da_state_free(*state);
>>   
>> -	return 0;
>> +	return error;
>>   }
>>   
>>   STATIC int
>> @@ -1241,70 +1279,123 @@ xfs_attr_node_remove_name(
>>   }
>>   
>>   /*
>> - * Remove a name from a B-tree attribute list.
>> + * Remove the attribute specified in @args.
>>    *
>>    * This will involve walking down the Btree, and may involve joining
>>    * leaf nodes and even joining intermediate nodes up to and including
>>    * the root node (a special case of an intermediate node).
>> + *
>> + * This routine is meant to function as either an in-line or 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_removename(
>> -	struct xfs_da_args	*args)
>> +int
>> +xfs_attr_remove_iter(
>> +	struct xfs_delattr_context	*dac)
>>   {
>> -	struct xfs_da_state	*state;
>> -	int			retval, error;
>> -	struct xfs_inode	*dp = args->dp;
>> +	struct xfs_da_args		*args = dac->da_args;
>> +	struct xfs_da_state		*state = dac->da_state;
>> +	int				retval, error;
>> +	struct xfs_inode		*dp = args->dp;
>>   
>>   	trace_xfs_attr_node_removename(args);
>>   
>> -	error = xfs_attr_node_removename_setup(args, &state);
>> -	if (error)
>> -		goto out;
>> +	switch (dac->dela_state) {
>> +	case XFS_DAS_UNINIT:
>> +		if (!xfs_inode_hasattr(dp))
>> +			return -ENOATTR;
>>   
>> -	/*
>> -	 * If there is an out-of-line value, de-allocate the blocks.
>> -	 * This is done before we remove 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_remove(args);
>> -		if (error)
>> -			goto out;
>> +		/*
>> +		 * Shortform or leaf formats don't require transaction rolls and
>> +		 * thus state transitions. Call the right helper and return.
>> +		 */
>> +		if (dp->i_afp->if_format == XFS_DINODE_FMT_LOCAL)
>> +			return xfs_attr_shortform_remove(args);
>> +
>> +		if (xfs_attr_is_leaf(dp))
>> +			return xfs_attr_leaf_removename(args);
>>   
>>   		/*
>> -		 * Refill the state structure with buffers, the prior calls
>> -		 * released our buffers.
>> +		 * Node format may require transaction rolls. Set up the
>> +		 * state context and fall into the state machine.
>>   		 */
>> -		error = xfs_attr_refillstate(state);
>> -		if (error)
>> -			goto out;
>> -	}
>> -	retval = xfs_attr_node_remove_name(args, state);
>> +		if (!dac->da_state) {
>> +			error = xfs_attr_node_removename_setup(dac);
>> +			if (error)
>> +				return error;
>> +			state = dac->da_state;
>> +		}
>> +
>> +		/* fallthrough */
>> +	case XFS_DAS_RMTBLK:
>> +		dac->dela_state = XFS_DAS_RMTBLK;
>>   
>> -	/*
>> -	 * Check to see if the tree needs to be collapsed.
>> -	 */
>> -	if (retval && (state->path.active > 1)) {
>> -		error = xfs_da3_join(state);
>> -		if (error)
>> -			goto out;
>> -		error = xfs_defer_finish(&args->trans);
>> -		if (error)
>> -			goto out;
>>   		/*
>> -		 * Commit the Btree join operation and start a new trans.
>> +		 * If there is an out-of-line value, de-allocate the blocks.
>> +		 * This is done before we remove the attribute so that we don't
>> +		 * overflow the maximum size of a transaction and/or hit a
>> +		 * deadlock.
>>   		 */
>> -		error = xfs_trans_roll_inode(&args->trans, dp);
>> -		if (error)
>> -			goto out;
>> -	}
>> +		if (args->rmtblkno > 0) {
>> +			/*
>> +			 * May return -EAGAIN. Roll and repeat until all remote
>> +			 * blocks are removed.
>> +			 */
>> +			error = __xfs_attr_rmtval_remove(dac);
>> +			if (error == -EAGAIN)
>> +				return error;
>> +			else if (error)
>> +				goto out;
>>   
>> -	/*
>> -	 * If the result is small enough, push it all into the inode.
>> -	 */
>> -	if (xfs_attr_is_leaf(dp))
>> -		error = xfs_attr_node_shrink(args, state);
>> +			/*
>> +			 * Refill the state structure with buffers (the prior
>> +			 * calls released our buffers) and close out this
>> +			 * transaction before proceeding.
>> +			 */
>> +			ASSERT(args->rmtblkno == 0);
>> +			error = xfs_attr_refillstate(state);
>> +			if (error)
>> +				goto out;
>> +			dac->dela_state = XFS_DAS_RM_NAME;
>> +			dac->flags |= XFS_DAC_DEFER_FINISH;
>> +			return -EAGAIN;
>> +		}
>> +
>> +		/* fallthrough */
>> +	case XFS_DAS_RM_NAME:
>> +		retval = xfs_attr_node_remove_name(args, state);
> 
> Hm.  I see a bunch of cleanup possibilities for after this series...
> 
> xfs_attr_shortform_remove
> xfs_attr_leaf_removename
> xfs_attr_node_remove_name
> 
> Can you add a patch to the end of the series renaming these to
> xfs_attr_{sf,leaf,node}_removename or something?
> 
> Also, can you refactor the chunk of code under "Remove the name and
> update the hashvals in the tree" in
> xfs_attr_node_addname_clear_incomplete to use xfs_attr_node_remove_name?
> 
> (Separate cleanup patches at the end of the series would be appreciated.)
Sure, that should be fine.  Do you want a patch for each?  Or just one 
clean up patch?

> 
>>   
>> +		/*
>> +		 * Check to see if the tree needs to be collapsed. If so, roll
>> +		 * the transacton and fall into the shrink state.
>> +		 */
>> +		if (retval && (state->path.active > 1)) {
>> +			error = xfs_da3_join(state);
>> +			if (error)
>> +				goto out;
>> +
>> +			dac->flags |= XFS_DAC_DEFER_FINISH;
>> +			dac->dela_state = XFS_DAS_RM_SHRINK;
>> +			return -EAGAIN;
>> +		}
>> +
>> +		/* fallthrough */
>> +	case XFS_DAS_RM_SHRINK:
>> +		/*
>> +		 * If the result is small enough, push it all into the inode.
>> +		 * This is our final state so it's safe to return a dirty
>> +		 * transaction.
>> +		 */
>> +		if (xfs_attr_is_leaf(dp))
>> +			error = xfs_attr_node_shrink(args, state);
>> +		ASSERT(error != -EAGAIN);
>> +		break;
>> +	default:
>> +		ASSERT(0);
>> +		error = -EINVAL;
>> +		goto out;
>> +	}
>>   out:
>>   	if (state)
>>   		xfs_da_state_free(state);
>> diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
>> index 2b1f619..32736d9 100644
>> --- a/fs/xfs/libxfs/xfs_attr.h
>> +++ b/fs/xfs/libxfs/xfs_attr.h
>> @@ -74,6 +74,133 @@ struct xfs_attr_list_context {
>>   };
>>   
>>   
>> +/*
>> + * ========================================================================
>> + * Structure used to pass context around among the delayed routines.
>> + * ========================================================================
>> + */
>> +
>> +/*
>> + * Below is a state machine diagram for attr remove operations. The  XFS_DAS_*
>> + * states indicate places where the function would return -EAGAIN, and then
>> + * immediately resume from after being recalled by the calling function. States
>> + * marked as a "subroutine state" indicate that they belong to a subroutine, and
>> + * so the calling function needs to pass them back to that subroutine to allow
>> + * it to finish where it left off. But they otherwise do not have a role in the
>> + * calling function other than just passing through.
>> + *
>> + * xfs_attr_remove_iter()
>> + *              │
>> + *              v
>> + *        have attr to remove? ──n──> done
>> + *              │
>> + *              y
>> + *              │
>> + *              v
>> + *        are we short form? ──y──> xfs_attr_shortform_remove ──> done
>> + *              │
>> + *              n
>> + *              │
>> + *              V
>> + *        are we leaf form? ──y──> xfs_attr_leaf_removename ──> done
>> + *              │
>> + *              n
>> + *              │
>> + *              V
>> + *   ┌── need to setup state?
>> + *   │          │
>> + *   n          y
>> + *   │          │
>> + *   │          v
>> + *   │ find attr and get state
>> + *   │    attr has blks? ───n────┐
> 
> Nit: This should be "attr has remote blks?" since everywhere else in the
> code we call them remote value blocks.
Ok, will fix
> 
>> + *   │          │                v
>> + *   │          │         find and invalidate
>> + *   │          y         the blocks. mark
> 
> remote blocks...
will fix

> 
>> + *   │          │         attr incomplete
>> + *   │          ├────────────────┘
>> + *   └──────────┤
>> + *              │
>> + *              v
>> + *      Have blks to remove? ───y─────────┐
>> + *              │        ^          remove the blks
> 
> remote blocks...
will fix

> 
>> + *              │        │                │
>> + *              │        │                v
>> + *              │  XFS_DAS_RMTBLK <─n── done?
>> + *              │  re-enter with          │
>> + *              │  one less blk to        y
>> + *              │      remove             │
>> + *              │                         V
>> + *              │                  refill the state
>> + *              n                         │
>> + *              │                         v
>> + *              │                   XFS_DAS_RM_NAME
>> + *              │                         │
>> + *              ├─────────────────────────┘
>> + *              │
>> + *              v
>> + *       remove leaf and
>> + *       update hash with
>> + *   xfs_attr_node_remove_cleanup
>> + *              │
>> + *              v
>> + *           need to
>> + *        shrink tree? ─n─┐
>> + *              │         │
>> + *              y         │
>> + *              │         │
>> + *              v         │
>> + *          join leaf     │
>> + *              │         │
>> + *              v         │
>> + *      XFS_DAS_RM_SHRINK │
>> + *              │         │
>> + *              v         │
>> + *       do the shrink    │
>> + *              │         │
>> + *              v         │
>> + *          free state <──┘
>> + *              │
>> + *              v
>> + *            done
>> + *
>> + */
>> +
>> +/*
>> + * Enum values for xfs_delattr_context.da_state
>> + *
>> + * These values are used by delayed attribute operations to keep track  of where
>> + * they were before they returned -EAGAIN.  A return code of -EAGAIN signals the
>> + * calling function to roll the transaction, and then recall the subroutine to
> 
> nit: s/recall/call the subroutine again/
Sure, will update

> 
>> + * finish the operation.  The enum is then used by the subroutine to jump back
>> + * to where it was and resume executing where it left off.
>> + */
>> +enum xfs_delattr_state {
>> +	XFS_DAS_UNINIT		= 0,  /* No state has been set yet */
>> +	XFS_DAS_RMTBLK,		      /* Removing remote blks */
>> +	XFS_DAS_RM_NAME,	      /* Remove attr name */
>> +	XFS_DAS_RM_SHRINK,	      /* We are shrinking the tree */
>> +};
>> +
>> +/*
>> + * Defines for xfs_delattr_context.flags
>> + */
>> +#define XFS_DAC_DEFER_FINISH		0x01 /* finish the transaction */
>> +
>> +/*
>> + * Context used for keeping track of delayed attribute operations
>> + */
>> +struct xfs_delattr_context {
>> +	struct xfs_da_args      *da_args;
>> +
>> +	/* Used in xfs_attr_node_removename to roll through removing blocks */
>> +	struct xfs_da_state     *da_state;
>> +
>> +	/* Used to keep track of current state of delayed operation */
>> +	unsigned int            flags;
>> +	enum xfs_delattr_state  dela_state;
>> +};
>> +
>>   /*========================================================================
>>    * Function prototypes for the kernel.
>>    *========================================================================*/
>> @@ -92,6 +219,10 @@ int xfs_attr_set(struct xfs_da_args *args);
>>   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);
>>   
>>   #endif	/* __XFS_ATTR_H__ */
>> diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
>> index 556184b..d97de20 100644
>> --- a/fs/xfs/libxfs/xfs_attr_leaf.c
>> +++ b/fs/xfs/libxfs/xfs_attr_leaf.c
>> @@ -19,8 +19,8 @@
>>   #include "xfs_bmap_btree.h"
>>   #include "xfs_bmap.h"
>>   #include "xfs_attr_sf.h"
>> -#include "xfs_attr_remote.h"
>>   #include "xfs_attr.h"
>> +#include "xfs_attr_remote.h"
>>   #include "xfs_attr_leaf.h"
>>   #include "xfs_error.h"
>>   #include "xfs_trace.h"
>> diff --git a/fs/xfs/libxfs/xfs_attr_remote.c b/fs/xfs/libxfs/xfs_attr_remote.c
>> index 48d8e9c..2f3c4cc 100644
>> --- a/fs/xfs/libxfs/xfs_attr_remote.c
>> +++ b/fs/xfs/libxfs/xfs_attr_remote.c
>> @@ -674,10 +674,12 @@ xfs_attr_rmtval_invalidate(
>>    */
>>   int
>>   xfs_attr_rmtval_remove(
>> -	struct xfs_da_args      *args)
>> +	struct xfs_da_args		*args)
>>   {
>> -	int			error;
>> -	int			retval;
>> +	int				error;
>> +	struct xfs_delattr_context	dac  = {
>> +		.da_args	= args,
>> +	};
>>   
>>   	trace_xfs_attr_rmtval_remove(args);
>>   
>> @@ -685,31 +687,29 @@ xfs_attr_rmtval_remove(
>>   	 * Keep de-allocating extents until the remote-value region is gone.
>>   	 */
>>   	do {
>> -		retval = __xfs_attr_rmtval_remove(args);
>> -		if (retval && retval != -EAGAIN)
>> -			return retval;
>> +		error = __xfs_attr_rmtval_remove(&dac);
>> +		if (error && error != -EAGAIN)
>> +			break;
>>   
>> -		/*
>> -		 * Close out trans and start the next one in the chain.
>> -		 */
>> -		error = xfs_trans_roll_inode(&args->trans, args->dp);
>> +		error = xfs_attr_trans_roll(&dac);
>>   		if (error)
>>   			return error;
>> -	} while (retval == -EAGAIN);
>> +	} while (true);
>>   
>> -	return 0;
>> +	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
>> + * buffer that it is stored on. Returns -EAGAIN for the caller to refresh the
>>    * transaction and re-call the function
>>    */
>>   int
>>   __xfs_attr_rmtval_remove(
>> -	struct xfs_da_args	*args)
>> +	struct xfs_delattr_context	*dac)
>>   {
>> -	int			error, done;
>> +	struct xfs_da_args		*args = dac->da_args;
>> +	int				error, done;
>>   
>>   	/*
>>   	 * Unmap value blocks for this attr.
>> @@ -719,12 +719,20 @@ __xfs_attr_rmtval_remove(
>>   	if (error)
>>   		return error;
>>   
>> -	error = xfs_defer_finish(&args->trans);
>> -	if (error)
>> -		return error;
>> -
>> -	if (!done)
>> +	/*
>> +	 * We don't need an explicit state here to pick up where we left off. We
>> +	 * can figure it out using the !done return code. Calling function only
>> +	 * needs to keep recalling this routine until we indicate to stop by
> 
> "Callers should keep calling this routine until it returns something
> other than -EAGAIN."
> 
> Also, that should go in the comment above the function.
Alrighty, will update
> 
> With all those fairly minor things fixed,
> Reviewed-by: Darrick J. Wong <djwong@kernel.org>
> 
Thanks!
Allison

> --D
> 
>> +	 * returning anything other than -EAGAIN. The actual value of
>> +	 * attr->xattri_dela_state may be some value reminiscent of the calling
>> +	 * function, but it's value is irrelevant with in the context of this
>> +	 * function. Once we are done here, the next state is set as needed
>> +	 * by the parent
>> +	 */
>> +	if (!done) {
>> +		dac->flags |= XFS_DAC_DEFER_FINISH;
>>   		return -EAGAIN;
>> +	}
>>   
>>   	return error;
>>   }
>> diff --git a/fs/xfs/libxfs/xfs_attr_remote.h b/fs/xfs/libxfs/xfs_attr_remote.h
>> index 9eee615..002fd30 100644
>> --- a/fs/xfs/libxfs/xfs_attr_remote.h
>> +++ b/fs/xfs/libxfs/xfs_attr_remote.h
>> @@ -14,5 +14,5 @@ int xfs_attr_rmtval_remove(struct xfs_da_args *args);
>>   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_da_args *args);
>> +int __xfs_attr_rmtval_remove(struct xfs_delattr_context *dac);
>>   #endif /* __XFS_ATTR_REMOTE_H__ */
>> diff --git a/fs/xfs/xfs_attr_inactive.c b/fs/xfs/xfs_attr_inactive.c
>> index bfad669..aaa7e66 100644
>> --- a/fs/xfs/xfs_attr_inactive.c
>> +++ b/fs/xfs/xfs_attr_inactive.c
>> @@ -15,10 +15,10 @@
>>   #include "xfs_da_format.h"
>>   #include "xfs_da_btree.h"
>>   #include "xfs_inode.h"
>> +#include "xfs_attr.h"
>>   #include "xfs_attr_remote.h"
>>   #include "xfs_trans.h"
>>   #include "xfs_bmap.h"
>> -#include "xfs_attr.h"
>>   #include "xfs_attr_leaf.h"
>>   #include "xfs_quota.h"
>>   #include "xfs_dir2.h"
>> -- 
>> 2.7.4
>>

Re: [PATCH RESEND v18 10/11] xfs: Add delay ready attr remove routines

[Darrick J. Wong]

On Fri, May 14, 2021 at 10:41:44PM -0700, Allison Henderson wrote:
> 
> 
> On 5/13/21 5:46 PM, Darrick J. Wong wrote:
> > On Wed, May 12, 2021 at 09:14:07AM -0700, Allison Henderson wrote:
> > > This patch modifies the attr remove 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_remove_args is merged with
> > > xfs_attr_node_removename become a new function, xfs_attr_remove_iter.
> > > This new version uses a sort of state machine like switch to keep track
> > > of where it was when EAGAIN was returned. A new version of
> > > xfs_attr_remove_args consists of a simple loop to refresh the
> > > transaction until the operation is completed. A new XFS_DAC_DEFER_FINISH
> > > flag is used to finish the transaction where ever the existing code used
> > > to.
> > > 
> > > Calls to xfs_attr_rmtval_remove are replaced with the delay ready
> > > version __xfs_attr_rmtval_remove. We will rename
> > > __xfs_attr_rmtval_remove back to xfs_attr_rmtval_remove when we are
> > > done.
> > > 
> > > xfs_attr_rmtval_remove itself is still in use by the set routines (used
> > > during a rename).  For reasons of preserving existing function, we
> > > modify xfs_attr_rmtval_remove to call xfs_defer_finish when the flag is
> > > set.  Similar to how xfs_attr_remove_args does here.  Once we transition
> > > the set routines to be delay ready, xfs_attr_rmtval_remove is no longer
> > > used and will be removed.
> > > 
> > > This patch also adds a new struct xfs_delattr_context, which we will use
> > > to keep track of the current state of an attribute operation. The new
> > > xfs_delattr_state enum is used to track various operations that are in
> > > progress so that we know not to repeat them, and resume where we left
> > > off before EAGAIN was returned to cycle out the transaction. Other
> > > members take the place of local variables that need to retain their
> > > values across multiple function recalls.  See xfs_attr.h for a more
> > > detailed diagram of the states.
> > > 
> > > Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> > > Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
> > > Reviewed-by: Brian Foster <bfoster@redhat.com>
> > > ---
> > >   fs/xfs/libxfs/xfs_attr.c        | 213 ++++++++++++++++++++++++++++------------
> > >   fs/xfs/libxfs/xfs_attr.h        | 131 ++++++++++++++++++++++++
> > >   fs/xfs/libxfs/xfs_attr_leaf.c   |   2 +-
> > >   fs/xfs/libxfs/xfs_attr_remote.c |  48 +++++----
> > >   fs/xfs/libxfs/xfs_attr_remote.h |   2 +-
> > >   fs/xfs/xfs_attr_inactive.c      |   2 +-
> > >   6 files changed, 314 insertions(+), 84 deletions(-)
> > > 
> > > diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> > > index 21f862e..a91fff6 100644
> > > --- a/fs/xfs/libxfs/xfs_attr.c
> > > +++ b/fs/xfs/libxfs/xfs_attr.c
> > > @@ -57,7 +57,6 @@ STATIC int xfs_attr_node_addname(struct xfs_da_args *args,
> > >   				 struct xfs_da_state *state);
> > >   STATIC int xfs_attr_node_addname_find_attr(struct xfs_da_args *args,
> > >   				 struct xfs_da_state **state);
> > > -STATIC int xfs_attr_node_removename(xfs_da_args_t *args);
> > >   STATIC int xfs_attr_node_addname_clear_incomplete(struct xfs_da_args *args);
> > >   STATIC int xfs_attr_node_hasname(xfs_da_args_t *args,
> > >   				 struct xfs_da_state **state);
> > > @@ -241,6 +240,31 @@ xfs_attr_is_shortform(
> > >   		ip->i_afp->if_nextents == 0);
> > >   }
> > > +/*
> > > + * Checks to see if a delayed attribute transaction should be rolled.  If so,
> > > + * transaction is finished or rolled as needed.
> > > + */
> > > +int
> > > +xfs_attr_trans_roll(
> > > +	struct xfs_delattr_context	*dac)
> > > +{
> > > +	struct xfs_da_args		*args = dac->da_args;
> > > +	int				error;
> > > +
> > > +	if (dac->flags & XFS_DAC_DEFER_FINISH) {
> > > +		/*
> > > +		 * The caller wants us to finish all the deferred ops so that we
> > > +		 * avoid pinning the log tail with a large number of deferred
> > > +		 * ops.
> > > +		 */
> > > +		dac->flags &= ~XFS_DAC_DEFER_FINISH;
> > > +		error = xfs_defer_finish(&args->trans);
> > > +	} else
> > > +		error = xfs_trans_roll_inode(&args->trans, args->dp);
> > > +
> > > +	return error;
> > > +}
> > > +
> > >   STATIC int
> > >   xfs_attr_set_fmt(
> > >   	struct xfs_da_args	*args)
> > > @@ -544,16 +568,25 @@ xfs_has_attr(
> > >    */
> > >   int
> > >   xfs_attr_remove_args(
> > > -	struct xfs_da_args      *args)
> > > +	struct xfs_da_args	*args)
> > >   {
> > > -	if (!xfs_inode_hasattr(args->dp))
> > > -		return -ENOATTR;
> > > +	int				error;
> > > +	struct xfs_delattr_context	dac = {
> > > +		.da_args	= args,
> > > +	};
> > > -	if (args->dp->i_afp->if_format == XFS_DINODE_FMT_LOCAL)
> > > -		return xfs_attr_shortform_remove(args);
> > > -	if (xfs_attr_is_leaf(args->dp))
> > > -		return xfs_attr_leaf_removename(args);
> > > -	return xfs_attr_node_removename(args);
> > > +	do {
> > > +		error = xfs_attr_remove_iter(&dac);
> > > +		if (error != -EAGAIN)
> > > +			break;
> > > +
> > > +		error = xfs_attr_trans_roll(&dac);
> > > +		if (error)
> > > +			return error;
> > > +
> > > +	} while (true);
> > > +
> > > +	return error;
> > >   }
> > >   /*
> > > @@ -1197,14 +1230,16 @@ xfs_attr_leaf_mark_incomplete(
> > >    */
> > >   STATIC
> > >   int xfs_attr_node_removename_setup(
> > > -	struct xfs_da_args	*args,
> > > -	struct xfs_da_state	**state)
> > > +	struct xfs_delattr_context	*dac)
> > >   {
> > > -	int			error;
> > > +	struct xfs_da_args		*args = dac->da_args;
> > > +	struct xfs_da_state		**state = &dac->da_state;
> > > +	int				error;
> > >   	error = xfs_attr_node_hasname(args, state);
> > >   	if (error != -EEXIST)
> > >   		return error;
> > > +	error = 0;
> > >   	ASSERT((*state)->path.blk[(*state)->path.active - 1].bp != NULL);
> > >   	ASSERT((*state)->path.blk[(*state)->path.active - 1].magic ==
> > > @@ -1213,12 +1248,15 @@ int xfs_attr_node_removename_setup(
> > >   	if (args->rmtblkno > 0) {
> > >   		error = xfs_attr_leaf_mark_incomplete(args, *state);
> > >   		if (error)
> > > -			return error;
> > > +			goto out;
> > > -		return xfs_attr_rmtval_invalidate(args);
> > > +		error = xfs_attr_rmtval_invalidate(args);
> > >   	}
> > > +out:
> > > +	if (error)
> > > +		xfs_da_state_free(*state);
> > > -	return 0;
> > > +	return error;
> > >   }
> > >   STATIC int
> > > @@ -1241,70 +1279,123 @@ xfs_attr_node_remove_name(
> > >   }
> > >   /*
> > > - * Remove a name from a B-tree attribute list.
> > > + * Remove the attribute specified in @args.
> > >    *
> > >    * This will involve walking down the Btree, and may involve joining
> > >    * leaf nodes and even joining intermediate nodes up to and including
> > >    * the root node (a special case of an intermediate node).
> > > + *
> > > + * This routine is meant to function as either an in-line or 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_removename(
> > > -	struct xfs_da_args	*args)
> > > +int
> > > +xfs_attr_remove_iter(
> > > +	struct xfs_delattr_context	*dac)
> > >   {
> > > -	struct xfs_da_state	*state;
> > > -	int			retval, error;
> > > -	struct xfs_inode	*dp = args->dp;
> > > +	struct xfs_da_args		*args = dac->da_args;
> > > +	struct xfs_da_state		*state = dac->da_state;
> > > +	int				retval, error;
> > > +	struct xfs_inode		*dp = args->dp;
> > >   	trace_xfs_attr_node_removename(args);
> > > -	error = xfs_attr_node_removename_setup(args, &state);
> > > -	if (error)
> > > -		goto out;
> > > +	switch (dac->dela_state) {
> > > +	case XFS_DAS_UNINIT:
> > > +		if (!xfs_inode_hasattr(dp))
> > > +			return -ENOATTR;
> > > -	/*
> > > -	 * If there is an out-of-line value, de-allocate the blocks.
> > > -	 * This is done before we remove 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_remove(args);
> > > -		if (error)
> > > -			goto out;
> > > +		/*
> > > +		 * Shortform or leaf formats don't require transaction rolls and
> > > +		 * thus state transitions. Call the right helper and return.
> > > +		 */
> > > +		if (dp->i_afp->if_format == XFS_DINODE_FMT_LOCAL)
> > > +			return xfs_attr_shortform_remove(args);
> > > +
> > > +		if (xfs_attr_is_leaf(dp))
> > > +			return xfs_attr_leaf_removename(args);
> > >   		/*
> > > -		 * Refill the state structure with buffers, the prior calls
> > > -		 * released our buffers.
> > > +		 * Node format may require transaction rolls. Set up the
> > > +		 * state context and fall into the state machine.
> > >   		 */
> > > -		error = xfs_attr_refillstate(state);
> > > -		if (error)
> > > -			goto out;
> > > -	}
> > > -	retval = xfs_attr_node_remove_name(args, state);
> > > +		if (!dac->da_state) {
> > > +			error = xfs_attr_node_removename_setup(dac);
> > > +			if (error)
> > > +				return error;
> > > +			state = dac->da_state;
> > > +		}
> > > +
> > > +		/* fallthrough */
> > > +	case XFS_DAS_RMTBLK:
> > > +		dac->dela_state = XFS_DAS_RMTBLK;
> > > -	/*
> > > -	 * Check to see if the tree needs to be collapsed.
> > > -	 */
> > > -	if (retval && (state->path.active > 1)) {
> > > -		error = xfs_da3_join(state);
> > > -		if (error)
> > > -			goto out;
> > > -		error = xfs_defer_finish(&args->trans);
> > > -		if (error)
> > > -			goto out;
> > >   		/*
> > > -		 * Commit the Btree join operation and start a new trans.
> > > +		 * If there is an out-of-line value, de-allocate the blocks.
> > > +		 * This is done before we remove the attribute so that we don't
> > > +		 * overflow the maximum size of a transaction and/or hit a
> > > +		 * deadlock.
> > >   		 */
> > > -		error = xfs_trans_roll_inode(&args->trans, dp);
> > > -		if (error)
> > > -			goto out;
> > > -	}
> > > +		if (args->rmtblkno > 0) {
> > > +			/*
> > > +			 * May return -EAGAIN. Roll and repeat until all remote
> > > +			 * blocks are removed.
> > > +			 */
> > > +			error = __xfs_attr_rmtval_remove(dac);
> > > +			if (error == -EAGAIN)
> > > +				return error;
> > > +			else if (error)
> > > +				goto out;
> > > -	/*
> > > -	 * If the result is small enough, push it all into the inode.
> > > -	 */
> > > -	if (xfs_attr_is_leaf(dp))
> > > -		error = xfs_attr_node_shrink(args, state);
> > > +			/*
> > > +			 * Refill the state structure with buffers (the prior
> > > +			 * calls released our buffers) and close out this
> > > +			 * transaction before proceeding.
> > > +			 */
> > > +			ASSERT(args->rmtblkno == 0);
> > > +			error = xfs_attr_refillstate(state);
> > > +			if (error)
> > > +				goto out;
> > > +			dac->dela_state = XFS_DAS_RM_NAME;
> > > +			dac->flags |= XFS_DAC_DEFER_FINISH;
> > > +			return -EAGAIN;
> > > +		}
> > > +
> > > +		/* fallthrough */
> > > +	case XFS_DAS_RM_NAME:
> > > +		retval = xfs_attr_node_remove_name(args, state);
> > 
> > Hm.  I see a bunch of cleanup possibilities for after this series...
> > 
> > xfs_attr_shortform_remove
> > xfs_attr_leaf_removename
> > xfs_attr_node_remove_name
> > 
> > Can you add a patch to the end of the series renaming these to
> > xfs_attr_{sf,leaf,node}_removename or something?
> > 
> > Also, can you refactor the chunk of code under "Remove the name and
> > update the hashvals in the tree" in
> > xfs_attr_node_addname_clear_incomplete to use xfs_attr_node_remove_name?
> > 
> > (Separate cleanup patches at the end of the series would be appreciated.)
> Sure, that should be fine.  Do you want a patch for each?  Or just one clean
> up patch?

One for all the function renaming, another for the quick hoist.

--D

> > 
> > > +		/*
> > > +		 * Check to see if the tree needs to be collapsed. If so, roll
> > > +		 * the transacton and fall into the shrink state.
> > > +		 */
> > > +		if (retval && (state->path.active > 1)) {
> > > +			error = xfs_da3_join(state);
> > > +			if (error)
> > > +				goto out;
> > > +
> > > +			dac->flags |= XFS_DAC_DEFER_FINISH;
> > > +			dac->dela_state = XFS_DAS_RM_SHRINK;
> > > +			return -EAGAIN;
> > > +		}
> > > +
> > > +		/* fallthrough */
> > > +	case XFS_DAS_RM_SHRINK:
> > > +		/*
> > > +		 * If the result is small enough, push it all into the inode.
> > > +		 * This is our final state so it's safe to return a dirty
> > > +		 * transaction.
> > > +		 */
> > > +		if (xfs_attr_is_leaf(dp))
> > > +			error = xfs_attr_node_shrink(args, state);
> > > +		ASSERT(error != -EAGAIN);
> > > +		break;
> > > +	default:
> > > +		ASSERT(0);
> > > +		error = -EINVAL;
> > > +		goto out;
> > > +	}
> > >   out:
> > >   	if (state)
> > >   		xfs_da_state_free(state);
> > > diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
> > > index 2b1f619..32736d9 100644
> > > --- a/fs/xfs/libxfs/xfs_attr.h
> > > +++ b/fs/xfs/libxfs/xfs_attr.h
> > > @@ -74,6 +74,133 @@ struct xfs_attr_list_context {
> > >   };
> > > +/*
> > > + * ========================================================================
> > > + * Structure used to pass context around among the delayed routines.
> > > + * ========================================================================
> > > + */
> > > +
> > > +/*
> > > + * Below is a state machine diagram for attr remove operations. The  XFS_DAS_*
> > > + * states indicate places where the function would return -EAGAIN, and then
> > > + * immediately resume from after being recalled by the calling function. States
> > > + * marked as a "subroutine state" indicate that they belong to a subroutine, and
> > > + * so the calling function needs to pass them back to that subroutine to allow
> > > + * it to finish where it left off. But they otherwise do not have a role in the
> > > + * calling function other than just passing through.
> > > + *
> > > + * xfs_attr_remove_iter()
> > > + *              │
> > > + *              v
> > > + *        have attr to remove? ──n──> done
> > > + *              │
> > > + *              y
> > > + *              │
> > > + *              v
> > > + *        are we short form? ──y──> xfs_attr_shortform_remove ──> done
> > > + *              │
> > > + *              n
> > > + *              │
> > > + *              V
> > > + *        are we leaf form? ──y──> xfs_attr_leaf_removename ──> done
> > > + *              │
> > > + *              n
> > > + *              │
> > > + *              V
> > > + *   ┌── need to setup state?
> > > + *   │          │
> > > + *   n          y
> > > + *   │          │
> > > + *   │          v
> > > + *   │ find attr and get state
> > > + *   │    attr has blks? ───n────┐
> > 
> > Nit: This should be "attr has remote blks?" since everywhere else in the
> > code we call them remote value blocks.
> Ok, will fix
> > 
> > > + *   │          │                v
> > > + *   │          │         find and invalidate
> > > + *   │          y         the blocks. mark
> > 
> > remote blocks...
> will fix
> 
> > 
> > > + *   │          │         attr incomplete
> > > + *   │          ├────────────────┘
> > > + *   └──────────┤
> > > + *              │
> > > + *              v
> > > + *      Have blks to remove? ───y─────────┐
> > > + *              │        ^          remove the blks
> > 
> > remote blocks...
> will fix
> 
> > 
> > > + *              │        │                │
> > > + *              │        │                v
> > > + *              │  XFS_DAS_RMTBLK <─n── done?
> > > + *              │  re-enter with          │
> > > + *              │  one less blk to        y
> > > + *              │      remove             │
> > > + *              │                         V
> > > + *              │                  refill the state
> > > + *              n                         │
> > > + *              │                         v
> > > + *              │                   XFS_DAS_RM_NAME
> > > + *              │                         │
> > > + *              ├─────────────────────────┘
> > > + *              │
> > > + *              v
> > > + *       remove leaf and
> > > + *       update hash with
> > > + *   xfs_attr_node_remove_cleanup
> > > + *              │
> > > + *              v
> > > + *           need to
> > > + *        shrink tree? ─n─┐
> > > + *              │         │
> > > + *              y         │
> > > + *              │         │
> > > + *              v         │
> > > + *          join leaf     │
> > > + *              │         │
> > > + *              v         │
> > > + *      XFS_DAS_RM_SHRINK │
> > > + *              │         │
> > > + *              v         │
> > > + *       do the shrink    │
> > > + *              │         │
> > > + *              v         │
> > > + *          free state <──┘
> > > + *              │
> > > + *              v
> > > + *            done
> > > + *
> > > + */
> > > +
> > > +/*
> > > + * Enum values for xfs_delattr_context.da_state
> > > + *
> > > + * These values are used by delayed attribute operations to keep track  of where
> > > + * they were before they returned -EAGAIN.  A return code of -EAGAIN signals the
> > > + * calling function to roll the transaction, and then recall the subroutine to
> > 
> > nit: s/recall/call the subroutine again/
> Sure, will update
> 
> > 
> > > + * finish the operation.  The enum is then used by the subroutine to jump back
> > > + * to where it was and resume executing where it left off.
> > > + */
> > > +enum xfs_delattr_state {
> > > +	XFS_DAS_UNINIT		= 0,  /* No state has been set yet */
> > > +	XFS_DAS_RMTBLK,		      /* Removing remote blks */
> > > +	XFS_DAS_RM_NAME,	      /* Remove attr name */
> > > +	XFS_DAS_RM_SHRINK,	      /* We are shrinking the tree */
> > > +};
> > > +
> > > +/*
> > > + * Defines for xfs_delattr_context.flags
> > > + */
> > > +#define XFS_DAC_DEFER_FINISH		0x01 /* finish the transaction */
> > > +
> > > +/*
> > > + * Context used for keeping track of delayed attribute operations
> > > + */
> > > +struct xfs_delattr_context {
> > > +	struct xfs_da_args      *da_args;
> > > +
> > > +	/* Used in xfs_attr_node_removename to roll through removing blocks */
> > > +	struct xfs_da_state     *da_state;
> > > +
> > > +	/* Used to keep track of current state of delayed operation */
> > > +	unsigned int            flags;
> > > +	enum xfs_delattr_state  dela_state;
> > > +};
> > > +
> > >   /*========================================================================
> > >    * Function prototypes for the kernel.
> > >    *========================================================================*/
> > > @@ -92,6 +219,10 @@ int xfs_attr_set(struct xfs_da_args *args);
> > >   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);
> > >   #endif	/* __XFS_ATTR_H__ */
> > > diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
> > > index 556184b..d97de20 100644
> > > --- a/fs/xfs/libxfs/xfs_attr_leaf.c
> > > +++ b/fs/xfs/libxfs/xfs_attr_leaf.c
> > > @@ -19,8 +19,8 @@
> > >   #include "xfs_bmap_btree.h"
> > >   #include "xfs_bmap.h"
> > >   #include "xfs_attr_sf.h"
> > > -#include "xfs_attr_remote.h"
> > >   #include "xfs_attr.h"
> > > +#include "xfs_attr_remote.h"
> > >   #include "xfs_attr_leaf.h"
> > >   #include "xfs_error.h"
> > >   #include "xfs_trace.h"
> > > diff --git a/fs/xfs/libxfs/xfs_attr_remote.c b/fs/xfs/libxfs/xfs_attr_remote.c
> > > index 48d8e9c..2f3c4cc 100644
> > > --- a/fs/xfs/libxfs/xfs_attr_remote.c
> > > +++ b/fs/xfs/libxfs/xfs_attr_remote.c
> > > @@ -674,10 +674,12 @@ xfs_attr_rmtval_invalidate(
> > >    */
> > >   int
> > >   xfs_attr_rmtval_remove(
> > > -	struct xfs_da_args      *args)
> > > +	struct xfs_da_args		*args)
> > >   {
> > > -	int			error;
> > > -	int			retval;
> > > +	int				error;
> > > +	struct xfs_delattr_context	dac  = {
> > > +		.da_args	= args,
> > > +	};
> > >   	trace_xfs_attr_rmtval_remove(args);
> > > @@ -685,31 +687,29 @@ xfs_attr_rmtval_remove(
> > >   	 * Keep de-allocating extents until the remote-value region is gone.
> > >   	 */
> > >   	do {
> > > -		retval = __xfs_attr_rmtval_remove(args);
> > > -		if (retval && retval != -EAGAIN)
> > > -			return retval;
> > > +		error = __xfs_attr_rmtval_remove(&dac);
> > > +		if (error && error != -EAGAIN)
> > > +			break;
> > > -		/*
> > > -		 * Close out trans and start the next one in the chain.
> > > -		 */
> > > -		error = xfs_trans_roll_inode(&args->trans, args->dp);
> > > +		error = xfs_attr_trans_roll(&dac);
> > >   		if (error)
> > >   			return error;
> > > -	} while (retval == -EAGAIN);
> > > +	} while (true);
> > > -	return 0;
> > > +	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
> > > + * buffer that it is stored on. Returns -EAGAIN for the caller to refresh the
> > >    * transaction and re-call the function
> > >    */
> > >   int
> > >   __xfs_attr_rmtval_remove(
> > > -	struct xfs_da_args	*args)
> > > +	struct xfs_delattr_context	*dac)
> > >   {
> > > -	int			error, done;
> > > +	struct xfs_da_args		*args = dac->da_args;
> > > +	int				error, done;
> > >   	/*
> > >   	 * Unmap value blocks for this attr.
> > > @@ -719,12 +719,20 @@ __xfs_attr_rmtval_remove(
> > >   	if (error)
> > >   		return error;
> > > -	error = xfs_defer_finish(&args->trans);
> > > -	if (error)
> > > -		return error;
> > > -
> > > -	if (!done)
> > > +	/*
> > > +	 * We don't need an explicit state here to pick up where we left off. We
> > > +	 * can figure it out using the !done return code. Calling function only
> > > +	 * needs to keep recalling this routine until we indicate to stop by
> > 
> > "Callers should keep calling this routine until it returns something
> > other than -EAGAIN."
> > 
> > Also, that should go in the comment above the function.
> Alrighty, will update
> > 
> > With all those fairly minor things fixed,
> > Reviewed-by: Darrick J. Wong <djwong@kernel.org>
> > 
> Thanks!
> Allison
> 
> > --D
> > 
> > > +	 * returning anything other than -EAGAIN. The actual value of
> > > +	 * attr->xattri_dela_state may be some value reminiscent of the calling
> > > +	 * function, but it's value is irrelevant with in the context of this
> > > +	 * function. Once we are done here, the next state is set as needed
> > > +	 * by the parent
> > > +	 */
> > > +	if (!done) {
> > > +		dac->flags |= XFS_DAC_DEFER_FINISH;
> > >   		return -EAGAIN;
> > > +	}
> > >   	return error;
> > >   }
> > > diff --git a/fs/xfs/libxfs/xfs_attr_remote.h b/fs/xfs/libxfs/xfs_attr_remote.h
> > > index 9eee615..002fd30 100644
> > > --- a/fs/xfs/libxfs/xfs_attr_remote.h
> > > +++ b/fs/xfs/libxfs/xfs_attr_remote.h
> > > @@ -14,5 +14,5 @@ int xfs_attr_rmtval_remove(struct xfs_da_args *args);
> > >   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_da_args *args);
> > > +int __xfs_attr_rmtval_remove(struct xfs_delattr_context *dac);
> > >   #endif /* __XFS_ATTR_REMOTE_H__ */
> > > diff --git a/fs/xfs/xfs_attr_inactive.c b/fs/xfs/xfs_attr_inactive.c
> > > index bfad669..aaa7e66 100644
> > > --- a/fs/xfs/xfs_attr_inactive.c
> > > +++ b/fs/xfs/xfs_attr_inactive.c
> > > @@ -15,10 +15,10 @@
> > >   #include "xfs_da_format.h"
> > >   #include "xfs_da_btree.h"
> > >   #include "xfs_inode.h"
> > > +#include "xfs_attr.h"
> > >   #include "xfs_attr_remote.h"
> > >   #include "xfs_trans.h"
> > >   #include "xfs_bmap.h"
> > > -#include "xfs_attr.h"
> > >   #include "xfs_attr_leaf.h"
> > >   #include "xfs_quota.h"
> > >   #include "xfs_dir2.h"
> > > -- 
> > > 2.7.4
> > > 

[PATCH RESEND v18 11/11] xfs: Add delay ready attr set routines

[Allison Henderson]

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_find_space 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>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Brian Foster <bfoster@redhat.com>
---
 fs/xfs/libxfs/xfs_attr.c        | 450 ++++++++++++++++++++++++----------------
 fs/xfs/libxfs/xfs_attr.h        | 272 +++++++++++++++++++++++-
 fs/xfs/libxfs/xfs_attr_remote.c | 100 ++++++---
 fs/xfs/libxfs/xfs_attr_remote.h |   5 +-
 fs/xfs/xfs_trace.h              |   1 -
 5 files changed, 608 insertions(+), 220 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index a91fff6..4096418 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -53,15 +53,16 @@ STATIC int xfs_attr_leaf_try_add(struct xfs_da_args *args, struct xfs_buf *bp);
  */
 STATIC int xfs_attr_node_get(xfs_da_args_t *args);
 STATIC void xfs_attr_restore_rmt_blk(struct xfs_da_args *args);
-STATIC int xfs_attr_node_addname(struct xfs_da_args *args,
-				 struct xfs_da_state *state);
-STATIC int xfs_attr_node_addname_find_attr(struct xfs_da_args *args,
-				 struct xfs_da_state **state);
-STATIC int xfs_attr_node_addname_clear_incomplete(struct xfs_da_args *args);
+STATIC int xfs_attr_node_addname(struct xfs_delattr_context *dac);
+STATIC int xfs_attr_node_addname_find_attr(struct xfs_delattr_context *dac);
+STATIC int xfs_attr_node_addname_clear_incomplete(
+				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_set_iter(struct xfs_delattr_context *dac,
+			     struct xfs_buf **leaf_bp);
 
 int
 xfs_inode_hasattr(
@@ -244,7 +245,7 @@ xfs_attr_is_shortform(
  * Checks to see if a delayed attribute transaction should be rolled.  If so,
  * transaction is finished or rolled as needed.
  */
-int
+STATIC int
 xfs_attr_trans_roll(
 	struct xfs_delattr_context	*dac)
 {
@@ -265,29 +266,58 @@ xfs_attr_trans_roll(
 	return error;
 }
 
+/*
+ * Set the attribute specified in @args.
+ */
+int
+xfs_attr_set_args(
+	struct xfs_da_args		*args)
+{
+	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) {
+			if (leaf_bp)
+				xfs_trans_brelse(args->trans, leaf_bp);
+			return error;
+		}
+	} while (true);
+
+	return error;
+}
+
 STATIC int
 xfs_attr_set_fmt(
-	struct xfs_da_args	*args)
+	struct xfs_delattr_context	*dac,
+	struct xfs_buf			**leaf_bp)
 {
-	struct xfs_buf          *leaf_bp = NULL;
-	struct xfs_inode	*dp = args->dp;
-	int			error2, error = 0;
+	struct xfs_da_args		*args = dac->da_args;
+	struct xfs_inode		*dp = args->dp;
+	int				error = 0;
 
 	/*
 	 * Try to add the attr to the attribute list in the inode.
 	 */
 	error = xfs_attr_try_sf_addname(dp, args);
-	if (error != -ENOSPC) {
-		error2 = xfs_trans_commit(args->trans);
-		args->trans = NULL;
-		return error ? error : error2;
-	}
+
+	/* Should only be 0, -EEXIST or -ENOSPC */
+	if (error != -ENOSPC)
+		return error;
 
 	/*
 	 * It won't fit in the shortform, transform to a leaf block.
 	 * GROT: another possible req'mt for a double-split btree op.
 	 */
-	error = xfs_attr_shortform_to_leaf(args, &leaf_bp);
+	error = xfs_attr_shortform_to_leaf(args, leaf_bp);
 	if (error)
 		return error;
 
@@ -296,102 +326,130 @@ xfs_attr_set_fmt(
 	 * concurrent AIL push cannot grab the half-baked leaf buffer
 	 * and run into problems 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;
-	}
+	xfs_trans_bhold(args->trans, *leaf_bp);
 
+	/*
+	 * We're still in XFS_DAS_UNINIT state here.  We've converted
+	 * the attr fork to leaf format and will restart with the leaf
+	 * add.
+	 */
+	dac->flags |= XFS_DAC_DEFER_FINISH;
 	return -EAGAIN;
 }
 
 /*
  * 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.
  */
 int
-xfs_attr_set_args(
-	struct xfs_da_args	*args)
+xfs_attr_set_iter(
+	struct xfs_delattr_context	*dac,
+	struct xfs_buf			**leaf_bp)
 {
-	struct xfs_inode	*dp = args->dp;
-	struct xfs_buf		*bp = NULL;
-	struct xfs_da_state     *state = NULL;
-	int			forkoff, error = 0;
+	struct xfs_da_args              *args = dac->da_args;
+	struct xfs_inode		*dp = args->dp;
+	struct xfs_buf			*bp = NULL;
+	int				forkoff, error = 0;
 
-	/*
-	 * 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.
-	 */
-	if (xfs_attr_is_shortform(dp)) {
-		error = xfs_attr_set_fmt(args);
-		if (error != -EAGAIN)
-			return error;
-	}
+	/* State machine switch */
+	switch (dac->dela_state) {
+	case XFS_DAS_UNINIT:
+		/*
+		 * If the fork is shortform, attempt to add the attr. If there
+		 * is no space, this converts to leaf format and returns
+		 * -EAGAIN with the leaf buffer held across the roll. The caller
+		 * will deal with a transaction roll error, but otherwise
+		 * release the hold once we return with a clean transaction.
+		 */
+		if (xfs_attr_is_shortform(dp))
+			return xfs_attr_set_fmt(dac, leaf_bp);
+		if (*leaf_bp != NULL) {
+			xfs_trans_bhold_release(args->trans, *leaf_bp);
+			*leaf_bp = NULL;
+		}
 
-	if (xfs_attr_is_leaf(dp)) {
-		error = xfs_attr_leaf_try_add(args, bp);
-		if (error == -ENOSPC) {
-			/*
-			 * Promote the attribute list to the Btree format.
-			 */
-			error = xfs_attr3_leaf_to_node(args);
-			if (error)
+		if (xfs_attr_is_leaf(dp)) {
+			error = xfs_attr_leaf_try_add(args, *leaf_bp);
+			if (error == -ENOSPC) {
+				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.
+				 *
+				 * At this point, we are still in
+				 * XFS_DAS_UNINIT, but when we come back, we'll
+				 * be a node, so we'll fall down into the node
+				 * handling code below
+				 */
+				dac->flags |= XFS_DAC_DEFER_FINISH;
+				return -EAGAIN;
+			} else 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);
+			dac->dela_state = XFS_DAS_FOUND_LBLK;
+		} else {
+			error = xfs_attr_node_addname_find_attr(dac);
 			if (error)
 				return error;
 
-			/*
-			 * Commit the current trans (including the inode) and
-			 * start a new one.
-			 */
-			error = xfs_trans_roll_inode(&args->trans, dp);
+			error = xfs_attr_node_addname(dac);
 			if (error)
 				return error;
 
-			goto node;
-		} else if (error) {
-			return error;
+			dac->dela_state = XFS_DAS_FOUND_NBLK;
 		}
-
-		/*
-		 * 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;
-
+		return -EAGAIN;
+	case XFS_DAS_FOUND_LBLK:
 		/*
 		 * 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) {
-			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;
+			}
+		}
+
+		/*
+		 * Repeat allocating remote blocks for the attr value until
+		 * blkcnt drops to zero.
+		 */
+		if (dac->blkcnt > 0) {
+			error = xfs_attr_rmtval_set_blk(dac);
 			if (error)
 				return error;
+			return -EAGAIN;
 		}
 
+		error = xfs_attr_rmtval_set_value(args);
+		if (error)
+			return error;
+
+		/*
+		 * If this is not a rename, clear the incomplete flag and we're
+		 * done.
+		 */
 		if (!(args->op_flags & XFS_DA_OP_RENAME)) {
-			/*
-			 * Added a "remote" value, just clear the incomplete
-			 *flag.
-			 */
 			if (args->rmtblkno > 0)
 				error = xfs_attr3_leaf_clearflag(args);
-
 			return error;
 		}
 
@@ -404,7 +462,6 @@ xfs_attr_set_args(
 		 * 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;
@@ -412,29 +469,37 @@ xfs_attr_set_args(
 		 * 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;
+	case XFS_DAS_FLIP_LFLAG:
 		/*
 		 * 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_LBLK:
+		/* Set state in case xfs_attr_rmtval_remove returns -EAGAIN */
+		dac->dela_state = XFS_DAS_RM_LBLK;
 		if (args->rmtblkno) {
-			error = xfs_attr_rmtval_invalidate(args);
+			error = __xfs_attr_rmtval_remove(dac);
 			if (error)
 				return error;
 
-			error = xfs_attr_rmtval_remove(args);
-			if (error)
-				return error;
+			dac->dela_state = XFS_DAS_RD_LEAF;
+			return -EAGAIN;
 		}
 
+		/* fallthrough */
+	case XFS_DAS_RD_LEAF:
 		/*
-		 * Read in the block containing the "old" attr, then remove the
-		 * "old" attr from that block (neat, huh!)
+		 * This is the last step for leaf format. Read the block with
+		 * the old attr, remove the old attr, check for shortform
+		 * conversion and return.
 		 */
 		error = xfs_attr3_leaf_read(args->trans, args->dp, args->blkno,
 					   &bp);
@@ -443,97 +508,116 @@ xfs_attr_set_args(
 
 		xfs_attr3_leaf_remove(bp, args);
 
-		/*
-		 * If the result is small enough, shrink it all into the inode.
-		 */
 		forkoff = xfs_attr_shortform_allfit(bp, dp);
 		if (forkoff)
 			error = xfs_attr3_leaf_to_shortform(bp, args, forkoff);
 			/* bp is gone due to xfs_da_shrink_inode */
 
 		return error;
-	}
-node:
 
+	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(dac);
+			if (error)
+				return error;
+		}
 
-	do {
-		error = xfs_attr_node_addname_find_attr(args, &state);
-		if (error)
-			return error;
-		error = xfs_attr_node_addname(args, state);
-	} while (error == -EAGAIN);
-	if (error)
-		return error;
+		/* fallthrough */
+	case XFS_DAS_ALLOC_NODE:
+		/*
+		 * 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.
+		 */
+		dac->dela_state = XFS_DAS_ALLOC_NODE;
+		if (args->rmtblkno > 0) {
+			if (dac->blkcnt > 0) {
+				error = xfs_attr_rmtval_set_blk(dac);
+				if (error)
+					return error;
+				return -EAGAIN;
+			}
+
+			error = xfs_attr_rmtval_set_value(args);
+			if (error)
+				return error;
+		}
 
-	/*
-	 * 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;
+		/*
+		 * 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 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) {
-		error = xfs_attr_rmtval_set(args);
+		/*
+		 * 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.
+		 */
+		error = xfs_attr3_leaf_flipflags(args);
 		if (error)
-			return error;
-	}
-
-	if (!(args->op_flags & XFS_DA_OP_RENAME)) {
+			goto out;
 		/*
-		 * Added a "remote" value, just clear the incomplete flag.
+		 * Commit the flag value change and start the next trans in
+		 * series
 		 */
-		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.
-	 */
-	error = xfs_attr3_leaf_flipflags(args);
-	if (error)
-		goto out;
-	/*
-	 * 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;
 
-	/*
-	 * Dismantle the "old" attribute/value pair by removing a "remote" value
-	 * (if it exists).
-	 */
-	xfs_attr_restore_rmt_blk(args);
+	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);
 
-	if (args->rmtblkno) {
 		error = xfs_attr_rmtval_invalidate(args);
 		if (error)
 			return error;
 
-		error = xfs_attr_rmtval_remove(args);
-		if (error)
-			return error;
-	}
+		/* fallthrough */
+	case XFS_DAS_RM_NBLK:
+		/* Set state in case xfs_attr_rmtval_remove returns -EAGAIN */
+		dac->dela_state = XFS_DAS_RM_NBLK;
+		if (args->rmtblkno) {
+			error = __xfs_attr_rmtval_remove(dac);
+			if (error)
+				return error;
+
+			dac->dela_state = XFS_DAS_CLR_FLAG;
+			return -EAGAIN;
+		}
 
-	error = xfs_attr_node_addname_clear_incomplete(args);
+		/* fallthrough */
+	case XFS_DAS_CLR_FLAG:
+		/*
+		 * The last state for node format. Look up the old attr and
+		 * remove it.
+		 */
+		error = xfs_attr_node_addname_clear_incomplete(dac);
+		break;
+	default:
+		ASSERT(dac->dela_state != XFS_DAS_RM_SHRINK);
+		break;
+	}
 out:
 	return error;
 }
 
+
 /*
  * Return EEXIST if attr is found, or ENOATTR if not
  */
@@ -997,18 +1081,18 @@ xfs_attr_node_hasname(
 
 STATIC int
 xfs_attr_node_addname_find_attr(
-	struct xfs_da_args	*args,
-	struct xfs_da_state     **state)
+	struct xfs_delattr_context	*dac)
 {
-	int			retval;
+	struct xfs_da_args		*args = dac->da_args;
+	int				retval;
 
 	/*
 	 * Search to see if name already exists, and get back a pointer
 	 * to where it should go.
 	 */
-	retval = xfs_attr_node_hasname(args, state);
+	retval = xfs_attr_node_hasname(args, &dac->da_state);
 	if (retval != -ENOATTR && retval != -EEXIST)
-		goto error;
+		return retval;
 
 	if (retval == -ENOATTR && (args->attr_flags & XATTR_REPLACE))
 		goto error;
@@ -1034,8 +1118,8 @@ xfs_attr_node_addname_find_attr(
 
 	return 0;
 error:
-	if (*state)
-		xfs_da_state_free(*state);
+	if (dac->da_state)
+		xfs_da_state_free(dac->da_state);
 	return retval;
 }
 
@@ -1048,19 +1132,23 @@ xfs_attr_node_addname_find_attr(
  *
  * "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_da_state	*state)
+	struct xfs_delattr_context	*dac)
 {
-	struct xfs_da_state_blk	*blk;
-	struct xfs_inode	*dp;
-	int			error;
+	struct xfs_da_args		*args = dac->da_args;
+	struct xfs_da_state		*state = dac->da_state;
+	struct xfs_da_state_blk		*blk;
+	int				error;
 
 	trace_xfs_attr_node_addname(args);
 
-	dp = args->dp;
 	blk = &state->path.blk[state->path.active-1];
 	ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
 
@@ -1077,18 +1165,15 @@ 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.
+			 * Now that we have converted the leaf to a node, we can
+			 * roll the transaction, and try xfs_attr3_leaf_add
+			 * again on re-entry.  No need to set dela_state to do
+			 * this. dela_state is still unset by this function at
+			 * this point.
 			 */
-			error = xfs_trans_roll_inode(&args->trans, dp);
-			if (error)
-				goto out;
-
+			dac->flags |= XFS_DAC_DEFER_FINISH;
 			return -EAGAIN;
 		}
 
@@ -1101,9 +1186,7 @@ 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.
@@ -1120,8 +1203,9 @@ xfs_attr_node_addname(
 
 STATIC
 int xfs_attr_node_addname_clear_incomplete(
-	struct xfs_da_args		*args)
+	struct xfs_delattr_context	*dac)
 {
+	struct xfs_da_args		*args = dac->da_args;
 	struct xfs_da_state		*state = NULL;
 	struct xfs_da_state_blk		*blk;
 	int				retval = 0;
diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
index 32736d9..41ad5e8 100644
--- a/fs/xfs/libxfs/xfs_attr.h
+++ b/fs/xfs/libxfs/xfs_attr.h
@@ -164,6 +164,262 @@ struct xfs_attr_list_context {
  *              v
  *            done
  *
+ *
+ * Below is a state machine diagram for attr set operations.
+ *
+ * It seems the challenge with understanding this system comes from trying to
+ * absorb the state machine all at once, when really one should only be looking
+ * at it with in the context of a single function. Once a state sensitive
+ * function is called, the idea is that it "takes ownership" of the
+ * state machine. It isn't concerned with the states that may have belonged to
+ * it's calling parent. Only the states relevant to itself or any other
+ * subroutines there in. Once a calling function hands off the state machine to
+ * a subroutine, it needs to respect the simple rule that it doesn't "own" the
+ * state machine anymore, and it's the responsibility of that calling function
+ * to propagate the -EAGAIN back up the call stack. Upon reentry, it is
+ * committed to re-calling that subroutine until it returns something other than
+ * -EAGAIN. Once that subroutine signals completion (by returning anything other
+ * than -EAGAIN), the calling function can resume using the state machine.
+ *
+ *  xfs_attr_set_iter()
+ *              │
+ *              v
+ *   ┌─y─ has an attr fork?
+ *   │          |
+ *   │          n
+ *   │          |
+ *   │          V
+ *   │       add a fork
+ *   │          │
+ *   └──────────┤
+ *              │
+ *              V
+ *   ┌─y─ is shortform?
+ *   │          │
+ *   │          V
+ *   │   xfs_attr_set_fmt
+ *   │          |
+ *   │          V
+ *   │ xfs_attr_try_sf_addname
+ *   │          │
+ *   │          V
+ *   │      had enough ──y──> done
+ *   │        space?
+ *   n          │
+ *   │          n
+ *   │          │
+ *   │          V
+ *   │   transform to leaf
+ *   │          │
+ *   │          V
+ *   │   hold the leaf buffer
+ *   │          │
+ *   │          V
+ *   │     return -EAGAIN
+ *   │      Re-enter in
+ *   │       leaf form
+ *   │
+ *   └─> release leaf buffer
+ *          if needed
+ *              │
+ *              V
+ *   ┌───n── fork has
+ *   │      only 1 blk?
+ *   │          │
+ *   │          y
+ *   │          │
+ *   │          v
+ *   │ xfs_attr_leaf_try_add()
+ *   │          │
+ *   │          v
+ *   │      had enough ──────────────y─────────────┐
+ *   │        space?                               │
+ *   │          │                                  │
+ *   │          n                                  │
+ *   │          │                                  │
+ *   │          v                                  │
+ *   │    return -EAGAIN                           │
+ *   │      re-enter in                            │
+ *   │        node form                            │
+ *   │          │                                  │
+ *   └──────────┤                                  │
+ *              │                                  │
+ *              V                                  │
+ * xfs_attr_node_addname_find_attr                 │
+ *        determines if this                       │
+ *       is create or rename                       │
+ *     find space to store attr                    │
+ *              │                                  │
+ *              v                                  │
+ *     xfs_attr_node_addname                       │
+ *              │                                  │
+ *              v                                  │
+ *   fits in a node leaf? ────n─────┐              │
+ *              │     ^             v              │
+ *              │     │       single leaf node?    │
+ *              │     │         │            │     │
+ *              y     │         y            n     │
+ *              │     │         │            │     │
+ *              v     │         v            v     │
+ *            update  │    grow the leaf  split if │
+ *           hashvals └── return -EAGAIN   needed  │
+ *              │         retry leaf add     │     │
+ *              │           on reentry       │     │
+ *              ├────────────────────────────┘     │
+ *              │                                  │
+ *              v                                  │
+ *         need to alloc                           │
+ *   ┌─y── or flip flag?                           │
+ *   │          │                                  │
+ *   │          n                                  │
+ *   │          │                                  │
+ *   │          v                                  │
+ *   │         done                                │
+ *   │                                             │
+ *   │                                             │
+ *   │         XFS_DAS_FOUND_LBLK <────────────────┘
+ *   │                  │
+ *   │                  V
+ *   │        xfs_attr_leaf_addname()
+ *   │                  │
+ *   │                  v
+ *   │      ┌──first time through?
+ *   │      │          │
+ *   │      │          y
+ *   │      │          │
+ *   │      n          v
+ *   │      │    if we have rmt blks
+ *   │      │    find space for them
+ *   │      │          │
+ *   │      └──────────┤
+ *   │                 │
+ *   │                 v
+ *   │            still have
+ *   │      ┌─n─ blks to alloc? <──┐
+ *   │      │          │           │
+ *   │      │          y           │
+ *   │      │          │           │
+ *   │      │          v           │
+ *   │      │     alloc one blk    │
+ *   │      │     return -EAGAIN ──┘
+ *   │      │    re-enter with one
+ *   │      │    less blk to alloc
+ *   │      │
+ *   │      │
+ *   │      └───> set the rmt
+ *   │               value
+ *   │                 │
+ *   │                 v
+ *   │               was this
+ *   │              a rename? ──n─┐
+ *   │                 │          │
+ *   │                 y          │
+ *   │                 │          │
+ *   │                 v          │
+ *   │           flip incomplete  │
+ *   │               flag         │
+ *   │                 │          │
+ *   │                 v          │
+ *   │         XFS_DAS_FLIP_LFLAG │
+ *   │                 │          │
+ *   │                 v          │
+ *   │          need to remove    │
+ *   │              old bks? ──n──┤
+ *   │                 │          │
+ *   │                 y          │
+ *   │                 │          │
+ *   │                 V          │
+ *   │               remove       │
+ *   │        ┌───> old blks      │
+ *   │        │        │          │
+ *   │ XFS_DAS_RM_LBLK │          │
+ *   │        ^        │          │
+ *   │        │        v          │
+ *   │        └──y── more to      │
+ *   │              remove?       │
+ *   │                 │          │
+ *   │                 n          │
+ *   │                 │          │
+ *   │                 v          │
+ *   │          XFS_DAS_RD_LEAF   │
+ *   │                 │          │
+ *   │                 v          │
+ *   │            remove leaf     │
+ *   │                 │          │
+ *   │                 v          │
+ *   │            shrink to sf    │
+ *   │             if needed      │
+ *   │                 │          │
+ *   │                 v          │
+ *   │                done <──────┘
+ *   │
+ *   └──────> XFS_DAS_FOUND_NBLK
+ *                     │
+ *                     v
+ *       ┌─────n──  need to
+ *       │        alloc blks?
+ *       │             │
+ *       │             y
+ *       │             │
+ *       │             v
+ *       │        find space
+ *       │             │
+ *       │             v
+ *       │  ┌─>XFS_DAS_ALLOC_NODE
+ *       │  │          │
+ *       │  │          v
+ *       │  │      alloc blk
+ *       │  │          │
+ *       │  │          v
+ *       │  └──y── need to alloc
+ *       │         more blocks?
+ *       │             │
+ *       │             n
+ *       │             │
+ *       │             v
+ *       │      set the rmt value
+ *       │             │
+ *       │             v
+ *       │          was this
+ *       └────────> a rename? ──n─┐
+ *                     │          │
+ *                     y          │
+ *                     │          │
+ *                     v          │
+ *               flip incomplete  │
+ *                   flag         │
+ *                     │          │
+ *                     v          │
+ *             XFS_DAS_FLIP_NFLAG │
+ *                     │          │
+ *                     v          │
+ *                 need to        │
+ *               remove blks? ─n──┤
+ *                     │          │
+ *                     y          │
+ *                     │          │
+ *                     v          │
+ *                   remove       │
+ *        ┌────────> old blks     │
+ *        │            │          │
+ *  XFS_DAS_RM_NBLK    │          │
+ *        ^            │          │
+ *        │            v          │
+ *        └──────y── more to      │
+ *                   remove       │
+ *                     │          │
+ *                     n          │
+ *                     │          │
+ *                     v          │
+ *              XFS_DAS_CLR_FLAG  │
+ *                     │          │
+ *                     v          │
+ *                clear flags     │
+ *                     │          │
+ *                     ├──────────┘
+ *                     │
+ *                     v
+ *                   done
  */
 
 /*
@@ -180,12 +436,22 @@ 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 */
+	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_RD_LEAF,	      /* Read in the new leaf */
+	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 */
+	XFS_DAS_CLR_FLAG,	      /* Clear incomplete flag */
 };
 
 /*
  * Defines for xfs_delattr_context.flags
  */
 #define XFS_DAC_DEFER_FINISH		0x01 /* finish the transaction */
+#define XFS_DAC_LEAF_ADDNAME_INIT	0x02 /* xfs_attr_leaf_addname init*/
 
 /*
  * Context used for keeping track of delayed attribute operations
@@ -193,6 +459,11 @@ 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;
 
@@ -220,7 +491,6 @@ 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 2f3c4cc..fc71f10 100644
--- a/fs/xfs/libxfs/xfs_attr_remote.c
+++ b/fs/xfs/libxfs/xfs_attr_remote.c
@@ -439,9 +439,9 @@ xfs_attr_rmtval_get(
 
 /*
  * Find a "hole" in the attribute address space large enough for us to drop the
- * new attribute's value into
+ * new attributes 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.
  */
@@ -669,37 +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 && 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..8ad68d5 100644
--- a/fs/xfs/libxfs/xfs_attr_remote.h
+++ b/fs/xfs/libxfs/xfs_attr_remote.h
@@ -10,9 +10,12 @@ int xfs_attr3_rmt_blocks(struct xfs_mount *mp, int attrlen);
 
 int xfs_attr_rmtval_get(struct xfs_da_args *args);
 int xfs_attr_rmtval_set(struct xfs_da_args *args);
-int xfs_attr_rmtval_remove(struct xfs_da_args *args);
 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 3c1c830..96f93a7 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -1943,7 +1943,6 @@ 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

Re: [PATCH RESEND v18 11/11] xfs: Add delay ready attr set routines

[Darrick J. Wong]

On Wed, May 12, 2021 at 09:14:08AM -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_find_space 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>
> Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
> Reviewed-by: Darrick J. Wong <djwong@kernel.org>

Heh, I already reviewed this, but I see a few things that could be
cleaned up a bit as a followon...

> Reviewed-by: Brian Foster <bfoster@redhat.com>
> ---
>  fs/xfs/libxfs/xfs_attr.c        | 450 ++++++++++++++++++++++++----------------
>  fs/xfs/libxfs/xfs_attr.h        | 272 +++++++++++++++++++++++-
>  fs/xfs/libxfs/xfs_attr_remote.c | 100 ++++++---
>  fs/xfs/libxfs/xfs_attr_remote.h |   5 +-
>  fs/xfs/xfs_trace.h              |   1 -
>  5 files changed, 608 insertions(+), 220 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index a91fff6..4096418 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
> @@ -53,15 +53,16 @@ STATIC int xfs_attr_leaf_try_add(struct xfs_da_args *args, struct xfs_buf *bp);
>   */
>  STATIC int xfs_attr_node_get(xfs_da_args_t *args);
>  STATIC void xfs_attr_restore_rmt_blk(struct xfs_da_args *args);
> -STATIC int xfs_attr_node_addname(struct xfs_da_args *args,
> -				 struct xfs_da_state *state);
> -STATIC int xfs_attr_node_addname_find_attr(struct xfs_da_args *args,
> -				 struct xfs_da_state **state);
> -STATIC int xfs_attr_node_addname_clear_incomplete(struct xfs_da_args *args);
> +STATIC int xfs_attr_node_addname(struct xfs_delattr_context *dac);
> +STATIC int xfs_attr_node_addname_find_attr(struct xfs_delattr_context *dac);
> +STATIC int xfs_attr_node_addname_clear_incomplete(
> +				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_set_iter(struct xfs_delattr_context *dac,
> +			     struct xfs_buf **leaf_bp);
>  
>  int
>  xfs_inode_hasattr(
> @@ -244,7 +245,7 @@ xfs_attr_is_shortform(
>   * Checks to see if a delayed attribute transaction should be rolled.  If so,
>   * transaction is finished or rolled as needed.
>   */
> -int
> +STATIC int
>  xfs_attr_trans_roll(
>  	struct xfs_delattr_context	*dac)
>  {
> @@ -265,29 +266,58 @@ xfs_attr_trans_roll(
>  	return error;
>  }
>  
> +/*
> + * Set the attribute specified in @args.
> + */
> +int
> +xfs_attr_set_args(
> +	struct xfs_da_args		*args)
> +{
> +	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) {
> +			if (leaf_bp)
> +				xfs_trans_brelse(args->trans, leaf_bp);
> +			return error;
> +		}
> +	} while (true);
> +
> +	return error;
> +}
> +
>  STATIC int
>  xfs_attr_set_fmt(
> -	struct xfs_da_args	*args)
> +	struct xfs_delattr_context	*dac,
> +	struct xfs_buf			**leaf_bp)
>  {
> -	struct xfs_buf          *leaf_bp = NULL;
> -	struct xfs_inode	*dp = args->dp;
> -	int			error2, error = 0;
> +	struct xfs_da_args		*args = dac->da_args;
> +	struct xfs_inode		*dp = args->dp;
> +	int				error = 0;
>  
>  	/*
>  	 * Try to add the attr to the attribute list in the inode.
>  	 */
>  	error = xfs_attr_try_sf_addname(dp, args);
> -	if (error != -ENOSPC) {
> -		error2 = xfs_trans_commit(args->trans);
> -		args->trans = NULL;
> -		return error ? error : error2;
> -	}
> +
> +	/* Should only be 0, -EEXIST or -ENOSPC */
> +	if (error != -ENOSPC)
> +		return error;
>  
>  	/*
>  	 * It won't fit in the shortform, transform to a leaf block.
>  	 * GROT: another possible req'mt for a double-split btree op.
>  	 */
> -	error = xfs_attr_shortform_to_leaf(args, &leaf_bp);
> +	error = xfs_attr_shortform_to_leaf(args, leaf_bp);
>  	if (error)
>  		return error;
>  
> @@ -296,102 +326,130 @@ xfs_attr_set_fmt(
>  	 * concurrent AIL push cannot grab the half-baked leaf buffer
>  	 * and run into problems 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;
> -	}
> +	xfs_trans_bhold(args->trans, *leaf_bp);
>  
> +	/*
> +	 * We're still in XFS_DAS_UNINIT state here.  We've converted
> +	 * the attr fork to leaf format and will restart with the leaf
> +	 * add.
> +	 */
> +	dac->flags |= XFS_DAC_DEFER_FINISH;
>  	return -EAGAIN;
>  }
>  
>  /*
>   * 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.
>   */
>  int
> -xfs_attr_set_args(
> -	struct xfs_da_args	*args)
> +xfs_attr_set_iter(
> +	struct xfs_delattr_context	*dac,
> +	struct xfs_buf			**leaf_bp)
>  {
> -	struct xfs_inode	*dp = args->dp;
> -	struct xfs_buf		*bp = NULL;
> -	struct xfs_da_state     *state = NULL;
> -	int			forkoff, error = 0;
> +	struct xfs_da_args              *args = dac->da_args;
> +	struct xfs_inode		*dp = args->dp;
> +	struct xfs_buf			*bp = NULL;
> +	int				forkoff, error = 0;
>  
> -	/*
> -	 * 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.
> -	 */
> -	if (xfs_attr_is_shortform(dp)) {
> -		error = xfs_attr_set_fmt(args);
> -		if (error != -EAGAIN)
> -			return error;
> -	}
> +	/* State machine switch */
> +	switch (dac->dela_state) {
> +	case XFS_DAS_UNINIT:
> +		/*
> +		 * If the fork is shortform, attempt to add the attr. If there
> +		 * is no space, this converts to leaf format and returns
> +		 * -EAGAIN with the leaf buffer held across the roll. The caller
> +		 * will deal with a transaction roll error, but otherwise
> +		 * release the hold once we return with a clean transaction.
> +		 */
> +		if (xfs_attr_is_shortform(dp))
> +			return xfs_attr_set_fmt(dac, leaf_bp);

More post-series renaming nits:

These probably ought to be renamed xfs_attr_sf_addname or something to go
with the _removename functions...


> +		if (*leaf_bp != NULL) {
> +			xfs_trans_bhold_release(args->trans, *leaf_bp);
> +			*leaf_bp = NULL;
> +		}
>  
> -	if (xfs_attr_is_leaf(dp)) {
> -		error = xfs_attr_leaf_try_add(args, bp);
> -		if (error == -ENOSPC) {
> -			/*
> -			 * Promote the attribute list to the Btree format.
> -			 */
> -			error = xfs_attr3_leaf_to_node(args);
> -			if (error)
> +		if (xfs_attr_is_leaf(dp)) {
> +			error = xfs_attr_leaf_try_add(args, *leaf_bp);
> +			if (error == -ENOSPC) {
> +				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.
> +				 *
> +				 * At this point, we are still in
> +				 * XFS_DAS_UNINIT, but when we come back, we'll
> +				 * be a node, so we'll fall down into the node
> +				 * handling code below
> +				 */
> +				dac->flags |= XFS_DAC_DEFER_FINISH;
> +				return -EAGAIN;
> +			} else 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);
> +			dac->dela_state = XFS_DAS_FOUND_LBLK;

Can you lift just whole if block into a separate xfs_attr_leaf_addname
function?  Especially since the state diagram indicates such a function
and would result in this chunk losing two levels of indent?

I know, we got rid of it three patches ago, but at least the replacement
would be shorter than the old version.

> +		} else {
> +			error = xfs_attr_node_addname_find_attr(dac);
>  			if (error)
>  				return error;
>  
> -			/*
> -			 * Commit the current trans (including the inode) and
> -			 * start a new one.
> -			 */
> -			error = xfs_trans_roll_inode(&args->trans, dp);
> +			error = xfs_attr_node_addname(dac);
>  			if (error)
>  				return error;
>  
> -			goto node;
> -		} else if (error) {
> -			return error;
> +			dac->dela_state = XFS_DAS_FOUND_NBLK;

... and then maybe this chunk can lose one level of indent?

>  		}
> -
> -		/*
> -		 * 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;
> -
> +		return -EAGAIN;
> +	case XFS_DAS_FOUND_LBLK:
>  		/*
>  		 * 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) {
> -			error = xfs_attr_rmtval_set(args);
> +
> +		/* Open coded xfs_attr_rmtval_set without trans handling */

xfs_attr_rmtval_set has no callers, is that just sitting around waiting
for the log item patchset coming next?


> +		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;
> +			}
> +		}
> +
> +		/*
> +		 * Repeat allocating remote blocks for the attr value until
> +		 * blkcnt drops to zero.
> +		 */
> +		if (dac->blkcnt > 0) {
> +			error = xfs_attr_rmtval_set_blk(dac);
>  			if (error)
>  				return error;
> +			return -EAGAIN;
>  		}
>  
> +		error = xfs_attr_rmtval_set_value(args);
> +		if (error)
> +			return error;
> +
> +		/*
> +		 * If this is not a rename, clear the incomplete flag and we're
> +		 * done.
> +		 */
>  		if (!(args->op_flags & XFS_DA_OP_RENAME)) {
> -			/*
> -			 * Added a "remote" value, just clear the incomplete
> -			 *flag.
> -			 */
>  			if (args->rmtblkno > 0)
>  				error = xfs_attr3_leaf_clearflag(args);
> -
>  			return error;
>  		}
>  
> @@ -404,7 +462,6 @@ xfs_attr_set_args(
>  		 * 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;
> @@ -412,29 +469,37 @@ xfs_attr_set_args(
>  		 * 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;
> +	case XFS_DAS_FLIP_LFLAG:
>  		/*
>  		 * 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_LBLK:
> +		/* Set state in case xfs_attr_rmtval_remove returns -EAGAIN */
> +		dac->dela_state = XFS_DAS_RM_LBLK;
>  		if (args->rmtblkno) {
> -			error = xfs_attr_rmtval_invalidate(args);
> +			error = __xfs_attr_rmtval_remove(dac);
>  			if (error)
>  				return error;
>  
> -			error = xfs_attr_rmtval_remove(args);
> -			if (error)
> -				return error;
> +			dac->dela_state = XFS_DAS_RD_LEAF;
> +			return -EAGAIN;
>  		}
>  
> +		/* fallthrough */
> +	case XFS_DAS_RD_LEAF:
>  		/*
> -		 * Read in the block containing the "old" attr, then remove the
> -		 * "old" attr from that block (neat, huh!)
> +		 * This is the last step for leaf format. Read the block with
> +		 * the old attr, remove the old attr, check for shortform
> +		 * conversion and return.
>  		 */
>  		error = xfs_attr3_leaf_read(args->trans, args->dp, args->blkno,
>  					   &bp);
> @@ -443,97 +508,116 @@ xfs_attr_set_args(
>  
>  		xfs_attr3_leaf_remove(bp, args);
>  
> -		/*
> -		 * If the result is small enough, shrink it all into the inode.
> -		 */
>  		forkoff = xfs_attr_shortform_allfit(bp, dp);
>  		if (forkoff)
>  			error = xfs_attr3_leaf_to_shortform(bp, args, forkoff);
>  			/* bp is gone due to xfs_da_shrink_inode */
>  
>  		return error;
> -	}
> -node:
>  
> +	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(dac);
> +			if (error)
> +				return error;
> +		}
>  
> -	do {
> -		error = xfs_attr_node_addname_find_attr(args, &state);
> -		if (error)
> -			return error;
> -		error = xfs_attr_node_addname(args, state);
> -	} while (error == -EAGAIN);
> -	if (error)
> -		return error;
> +		/* fallthrough */
> +	case XFS_DAS_ALLOC_NODE:
> +		/*
> +		 * 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.
> +		 */
> +		dac->dela_state = XFS_DAS_ALLOC_NODE;
> +		if (args->rmtblkno > 0) {
> +			if (dac->blkcnt > 0) {
> +				error = xfs_attr_rmtval_set_blk(dac);
> +				if (error)
> +					return error;
> +				return -EAGAIN;
> +			}
> +
> +			error = xfs_attr_rmtval_set_value(args);
> +			if (error)
> +				return error;
> +		}
>  
> -	/*
> -	 * 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;
> +		/*
> +		 * 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 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) {
> -		error = xfs_attr_rmtval_set(args);
> +		/*
> +		 * 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.
> +		 */
> +		error = xfs_attr3_leaf_flipflags(args);
>  		if (error)
> -			return error;
> -	}
> -
> -	if (!(args->op_flags & XFS_DA_OP_RENAME)) {
> +			goto out;
>  		/*
> -		 * Added a "remote" value, just clear the incomplete flag.
> +		 * Commit the flag value change and start the next trans in
> +		 * series
>  		 */
> -		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.
> -	 */
> -	error = xfs_attr3_leaf_flipflags(args);
> -	if (error)
> -		goto out;
> -	/*
> -	 * 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;
>  
> -	/*
> -	 * Dismantle the "old" attribute/value pair by removing a "remote" value
> -	 * (if it exists).
> -	 */
> -	xfs_attr_restore_rmt_blk(args);
> +	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);
>  
> -	if (args->rmtblkno) {
>  		error = xfs_attr_rmtval_invalidate(args);
>  		if (error)
>  			return error;
>  
> -		error = xfs_attr_rmtval_remove(args);
> -		if (error)
> -			return error;
> -	}
> +		/* fallthrough */
> +	case XFS_DAS_RM_NBLK:
> +		/* Set state in case xfs_attr_rmtval_remove returns -EAGAIN */
> +		dac->dela_state = XFS_DAS_RM_NBLK;
> +		if (args->rmtblkno) {
> +			error = __xfs_attr_rmtval_remove(dac);
> +			if (error)
> +				return error;
> +
> +			dac->dela_state = XFS_DAS_CLR_FLAG;
> +			return -EAGAIN;
> +		}
>  
> -	error = xfs_attr_node_addname_clear_incomplete(args);
> +		/* fallthrough */
> +	case XFS_DAS_CLR_FLAG:
> +		/*
> +		 * The last state for node format. Look up the old attr and
> +		 * remove it.
> +		 */
> +		error = xfs_attr_node_addname_clear_incomplete(dac);
> +		break;
> +	default:
> +		ASSERT(dac->dela_state != XFS_DAS_RM_SHRINK);

How would we end up in RM_SHRINK?  Isn't that only set in the remove
path?

> +		break;
> +	}
>  out:
>  	return error;
>  }
>  
> +
>  /*
>   * Return EEXIST if attr is found, or ENOATTR if not
>   */
> @@ -997,18 +1081,18 @@ xfs_attr_node_hasname(
>  
>  STATIC int
>  xfs_attr_node_addname_find_attr(
> -	struct xfs_da_args	*args,
> -	struct xfs_da_state     **state)
> +	struct xfs_delattr_context	*dac)
>  {
> -	int			retval;
> +	struct xfs_da_args		*args = dac->da_args;
> +	int				retval;
>  
>  	/*
>  	 * Search to see if name already exists, and get back a pointer
>  	 * to where it should go.
>  	 */
> -	retval = xfs_attr_node_hasname(args, state);
> +	retval = xfs_attr_node_hasname(args, &dac->da_state);
>  	if (retval != -ENOATTR && retval != -EEXIST)
> -		goto error;
> +		return retval;
>  
>  	if (retval == -ENOATTR && (args->attr_flags & XATTR_REPLACE))
>  		goto error;
> @@ -1034,8 +1118,8 @@ xfs_attr_node_addname_find_attr(
>  
>  	return 0;
>  error:
> -	if (*state)
> -		xfs_da_state_free(*state);
> +	if (dac->da_state)
> +		xfs_da_state_free(dac->da_state);
>  	return retval;
>  }
>  
> @@ -1048,19 +1132,23 @@ xfs_attr_node_addname_find_attr(
>   *
>   * "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_da_state	*state)
> +	struct xfs_delattr_context	*dac)
>  {
> -	struct xfs_da_state_blk	*blk;
> -	struct xfs_inode	*dp;
> -	int			error;
> +	struct xfs_da_args		*args = dac->da_args;
> +	struct xfs_da_state		*state = dac->da_state;
> +	struct xfs_da_state_blk		*blk;
> +	int				error;
>  
>  	trace_xfs_attr_node_addname(args);
>  
> -	dp = args->dp;
>  	blk = &state->path.blk[state->path.active-1];
>  	ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
>  
> @@ -1077,18 +1165,15 @@ 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.
> +			 * Now that we have converted the leaf to a node, we can
> +			 * roll the transaction, and try xfs_attr3_leaf_add
> +			 * again on re-entry.  No need to set dela_state to do
> +			 * this. dela_state is still unset by this function at
> +			 * this point.
>  			 */
> -			error = xfs_trans_roll_inode(&args->trans, dp);
> -			if (error)
> -				goto out;
> -
> +			dac->flags |= XFS_DAC_DEFER_FINISH;
>  			return -EAGAIN;
>  		}
>  
> @@ -1101,9 +1186,7 @@ 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.
> @@ -1120,8 +1203,9 @@ xfs_attr_node_addname(
>  
>  STATIC
>  int xfs_attr_node_addname_clear_incomplete(
> -	struct xfs_da_args		*args)
> +	struct xfs_delattr_context	*dac)
>  {
> +	struct xfs_da_args		*args = dac->da_args;
>  	struct xfs_da_state		*state = NULL;
>  	struct xfs_da_state_blk		*blk;
>  	int				retval = 0;
> diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
> index 32736d9..41ad5e8 100644
> --- a/fs/xfs/libxfs/xfs_attr.h
> +++ b/fs/xfs/libxfs/xfs_attr.h
> @@ -164,6 +164,262 @@ struct xfs_attr_list_context {
>   *              v
>   *            done
>   *
> + *
> + * Below is a state machine diagram for attr set operations.
> + *
> + * It seems the challenge with understanding this system comes from trying to
> + * absorb the state machine all at once, when really one should only be looking
> + * at it with in the context of a single function. Once a state sensitive
> + * function is called, the idea is that it "takes ownership" of the
> + * state machine. It isn't concerned with the states that may have belonged to
> + * it's calling parent. Only the states relevant to itself or any other
> + * subroutines there in. Once a calling function hands off the state machine to
> + * a subroutine, it needs to respect the simple rule that it doesn't "own" the
> + * state machine anymore, and it's the responsibility of that calling function
> + * to propagate the -EAGAIN back up the call stack. Upon reentry, it is
> + * committed to re-calling that subroutine until it returns something other than
> + * -EAGAIN. Once that subroutine signals completion (by returning anything other
> + * than -EAGAIN), the calling function can resume using the state machine.
> + *
> + *  xfs_attr_set_iter()
> + *              │
> + *              v
> + *   ┌─y─ has an attr fork?
> + *   │          |
> + *   │          n
> + *   │          |
> + *   │          V
> + *   │       add a fork
> + *   │          │
> + *   └──────────┤
> + *              │
> + *              V
> + *   ┌─y─ is shortform?
> + *   │          │
> + *   │          V
> + *   │   xfs_attr_set_fmt
> + *   │          |
> + *   │          V
> + *   │ xfs_attr_try_sf_addname
> + *   │          │
> + *   │          V
> + *   │      had enough ──y──> done
> + *   │        space?
> + *   n          │

About  ^^^ this line crawling down the left side of the flowchart:

How do we go from "y" -> "n" ?  Is that a clerical error?

> + *   │          n
> + *   │          │
> + *   │          V
> + *   │   transform to leaf
> + *   │          │
> + *   │          V
> + *   │   hold the leaf buffer
> + *   │          │
> + *   │          V
> + *   │     return -EAGAIN
> + *   │      Re-enter in
> + *   │       leaf form
> + *   │
> + *   └─> release leaf buffer
> + *          if needed
> + *              │
> + *              V
> + *   ┌───n── fork has
> + *   │      only 1 blk?
> + *   │          │
> + *   │          y
> + *   │          │
> + *   │          v
> + *   │ xfs_attr_leaf_try_add()
> + *   │          │
> + *   │          v
> + *   │      had enough ──────────────y─────────────┐
> + *   │        space?                               │
> + *   │          │                                  │
> + *   │          n                                  │
> + *   │          │                                  │
> + *   │          v                                  │
> + *   │    return -EAGAIN                           │
> + *   │      re-enter in                            │
> + *   │        node form                            │
> + *   │          │                                  │
> + *   └──────────┤                                  │
> + *              │                                  │
> + *              V                                  │
> + * xfs_attr_node_addname_find_attr                 │
> + *        determines if this                       │
> + *       is create or rename                       │
> + *     find space to store attr                    │
> + *              │                                  │
> + *              v                                  │
> + *     xfs_attr_node_addname                       │
> + *              │                                  │
> + *              v                                  │
> + *   fits in a node leaf? ────n─────┐              │
> + *              │     ^             v              │
> + *              │     │       single leaf node?    │
> + *              │     │         │            │     │
> + *              y     │         y            n     │
> + *              │     │         │            │     │
> + *              v     │         v            v     │
> + *            update  │    grow the leaf  split if │
> + *           hashvals └── return -EAGAIN   needed  │
> + *              │         retry leaf add     │     │
> + *              │           on reentry       │     │
> + *              ├────────────────────────────┘     │
> + *              │                                  │
> + *              v                                  │
> + *         need to alloc                           │
> + *   ┌─y── or flip flag?                           │
> + *   │          │                                  │
> + *   │          n                                  │
> + *   │          │                                  │
> + *   │          v                                  │
> + *   │         done                                │
> + *   │                                             │
> + *   │                                             │
> + *   │         XFS_DAS_FOUND_LBLK <────────────────┘
> + *   │                  │
> + *   │                  V
> + *   │        xfs_attr_leaf_addname()
> + *   │                  │
> + *   │                  v
> + *   │      ┌──first time through?
> + *   │      │          │
> + *   │      │          y
> + *   │      │          │
> + *   │      n          v
> + *   │      │    if we have rmt blks
> + *   │      │    find space for them
> + *   │      │          │
> + *   │      └──────────┤
> + *   │                 │
> + *   │                 v
> + *   │            still have
> + *   │      ┌─n─ blks to alloc? <──┐
> + *   │      │          │           │
> + *   │      │          y           │
> + *   │      │          │           │
> + *   │      │          v           │
> + *   │      │     alloc one blk    │
> + *   │      │     return -EAGAIN ──┘
> + *   │      │    re-enter with one
> + *   │      │    less blk to alloc
> + *   │      │
> + *   │      │
> + *   │      └───> set the rmt
> + *   │               value
> + *   │                 │
> + *   │                 v
> + *   │               was this
> + *   │              a rename? ──n─┐
> + *   │                 │          │
> + *   │                 y          │
> + *   │                 │          │
> + *   │                 v          │
> + *   │           flip incomplete  │
> + *   │               flag         │
> + *   │                 │          │
> + *   │                 v          │
> + *   │         XFS_DAS_FLIP_LFLAG │
> + *   │                 │          │
> + *   │                 v          │
> + *   │          need to remove    │
> + *   │              old bks? ──n──┤
> + *   │                 │          │
> + *   │                 y          │
> + *   │                 │          │
> + *   │                 V          │
> + *   │               remove       │
> + *   │        ┌───> old blks      │
> + *   │        │        │          │
> + *   │ XFS_DAS_RM_LBLK │          │
> + *   │        ^        │          │
> + *   │        │        v          │
> + *   │        └──y── more to      │
> + *   │              remove?       │
> + *   │                 │          │
> + *   │                 n          │
> + *   │                 │          │
> + *   │                 v          │
> + *   │          XFS_DAS_RD_LEAF   │
> + *   │                 │          │
> + *   │                 v          │
> + *   │            remove leaf     │
> + *   │                 │          │
> + *   │                 v          │
> + *   │            shrink to sf    │
> + *   │             if needed      │
> + *   │                 │          │
> + *   │                 v          │
> + *   │                done <──────┘
> + *   │
> + *   └──────> XFS_DAS_FOUND_NBLK
> + *                     │
> + *                     v
> + *       ┌─────n──  need to
> + *       │        alloc blks?
> + *       │             │
> + *       │             y
> + *       │             │
> + *       │             v
> + *       │        find space
> + *       │             │
> + *       │             v
> + *       │  ┌─>XFS_DAS_ALLOC_NODE
> + *       │  │          │
> + *       │  │          v
> + *       │  │      alloc blk
> + *       │  │          │
> + *       │  │          v
> + *       │  └──y── need to alloc
> + *       │         more blocks?
> + *       │             │
> + *       │             n
> + *       │             │
> + *       │             v
> + *       │      set the rmt value
> + *       │             │
> + *       │             v
> + *       │          was this
> + *       └────────> a rename? ──n─┐
> + *                     │          │
> + *                     y          │
> + *                     │          │
> + *                     v          │
> + *               flip incomplete  │
> + *                   flag         │
> + *                     │          │
> + *                     v          │
> + *             XFS_DAS_FLIP_NFLAG │
> + *                     │          │
> + *                     v          │
> + *                 need to        │
> + *               remove blks? ─n──┤
> + *                     │          │
> + *                     y          │
> + *                     │          │
> + *                     v          │
> + *                   remove       │
> + *        ┌────────> old blks     │
> + *        │            │          │
> + *  XFS_DAS_RM_NBLK    │          │
> + *        ^            │          │
> + *        │            v          │
> + *        └──────y── more to      │
> + *                   remove       │
> + *                     │          │
> + *                     n          │
> + *                     │          │
> + *                     v          │
> + *              XFS_DAS_CLR_FLAG  │
> + *                     │          │
> + *                     v          │
> + *                clear flags     │
> + *                     │          │
> + *                     ├──────────┘
> + *                     │
> + *                     v
> + *                   done
>   */
>  
>  /*
> @@ -180,12 +436,22 @@ 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 */
> +	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_RD_LEAF,	      /* Read in the new leaf */
> +	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 */
> +	XFS_DAS_CLR_FLAG,	      /* Clear incomplete flag */
>  };
>  
>  /*
>   * Defines for xfs_delattr_context.flags
>   */
>  #define XFS_DAC_DEFER_FINISH		0x01 /* finish the transaction */
> +#define XFS_DAC_LEAF_ADDNAME_INIT	0x02 /* xfs_attr_leaf_addname init*/
>  
>  /*
>   * Context used for keeping track of delayed attribute operations
> @@ -193,6 +459,11 @@ 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;
>  
> @@ -220,7 +491,6 @@ 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 2f3c4cc..fc71f10 100644
> --- a/fs/xfs/libxfs/xfs_attr_remote.c
> +++ b/fs/xfs/libxfs/xfs_attr_remote.c
> @@ -439,9 +439,9 @@ xfs_attr_rmtval_get(
>  
>  /*
>   * Find a "hole" in the attribute address space large enough for us to drop the
> - * new attribute's value into
> + * new attributes 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);

Nit: indent two tabs for the second and third lines.

--D

> +	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.
>   */
> @@ -669,37 +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 && 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..8ad68d5 100644
> --- a/fs/xfs/libxfs/xfs_attr_remote.h
> +++ b/fs/xfs/libxfs/xfs_attr_remote.h
> @@ -10,9 +10,12 @@ int xfs_attr3_rmt_blocks(struct xfs_mount *mp, int attrlen);
>  
>  int xfs_attr_rmtval_get(struct xfs_da_args *args);
>  int xfs_attr_rmtval_set(struct xfs_da_args *args);
> -int xfs_attr_rmtval_remove(struct xfs_da_args *args);
>  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 3c1c830..96f93a7 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -1943,7 +1943,6 @@ 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
> 

Re: [PATCH RESEND v18 11/11] xfs: Add delay ready attr set routines

[Allison Henderson]

On 5/13/21 6:14 PM, Darrick J. Wong wrote:
> On Wed, May 12, 2021 at 09:14:08AM -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_find_space 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>
>> Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
>> Reviewed-by: Darrick J. Wong <djwong@kernel.org>
> 
> Heh, I already reviewed this, but I see a few things that could be
> cleaned up a bit as a followon...
> 
>> Reviewed-by: Brian Foster <bfoster@redhat.com>
>> ---
>>   fs/xfs/libxfs/xfs_attr.c        | 450 ++++++++++++++++++++++++----------------
>>   fs/xfs/libxfs/xfs_attr.h        | 272 +++++++++++++++++++++++-
>>   fs/xfs/libxfs/xfs_attr_remote.c | 100 ++++++---
>>   fs/xfs/libxfs/xfs_attr_remote.h |   5 +-
>>   fs/xfs/xfs_trace.h              |   1 -
>>   5 files changed, 608 insertions(+), 220 deletions(-)
>>
>> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
>> index a91fff6..4096418 100644
>> --- a/fs/xfs/libxfs/xfs_attr.c
>> +++ b/fs/xfs/libxfs/xfs_attr.c
>> @@ -53,15 +53,16 @@ STATIC int xfs_attr_leaf_try_add(struct xfs_da_args *args, struct xfs_buf *bp);
>>    */
>>   STATIC int xfs_attr_node_get(xfs_da_args_t *args);
>>   STATIC void xfs_attr_restore_rmt_blk(struct xfs_da_args *args);
>> -STATIC int xfs_attr_node_addname(struct xfs_da_args *args,
>> -				 struct xfs_da_state *state);
>> -STATIC int xfs_attr_node_addname_find_attr(struct xfs_da_args *args,
>> -				 struct xfs_da_state **state);
>> -STATIC int xfs_attr_node_addname_clear_incomplete(struct xfs_da_args *args);
>> +STATIC int xfs_attr_node_addname(struct xfs_delattr_context *dac);
>> +STATIC int xfs_attr_node_addname_find_attr(struct xfs_delattr_context *dac);
>> +STATIC int xfs_attr_node_addname_clear_incomplete(
>> +				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_set_iter(struct xfs_delattr_context *dac,
>> +			     struct xfs_buf **leaf_bp);
>>   
>>   int
>>   xfs_inode_hasattr(
>> @@ -244,7 +245,7 @@ xfs_attr_is_shortform(
>>    * Checks to see if a delayed attribute transaction should be rolled.  If so,
>>    * transaction is finished or rolled as needed.
>>    */
>> -int
>> +STATIC int
>>   xfs_attr_trans_roll(
>>   	struct xfs_delattr_context	*dac)
>>   {
>> @@ -265,29 +266,58 @@ xfs_attr_trans_roll(
>>   	return error;
>>   }
>>   
>> +/*
>> + * Set the attribute specified in @args.
>> + */
>> +int
>> +xfs_attr_set_args(
>> +	struct xfs_da_args		*args)
>> +{
>> +	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) {
>> +			if (leaf_bp)
>> +				xfs_trans_brelse(args->trans, leaf_bp);
>> +			return error;
>> +		}
>> +	} while (true);
>> +
>> +	return error;
>> +}
>> +
>>   STATIC int
>>   xfs_attr_set_fmt(
>> -	struct xfs_da_args	*args)
>> +	struct xfs_delattr_context	*dac,
>> +	struct xfs_buf			**leaf_bp)
>>   {
>> -	struct xfs_buf          *leaf_bp = NULL;
>> -	struct xfs_inode	*dp = args->dp;
>> -	int			error2, error = 0;
>> +	struct xfs_da_args		*args = dac->da_args;
>> +	struct xfs_inode		*dp = args->dp;
>> +	int				error = 0;
>>   
>>   	/*
>>   	 * Try to add the attr to the attribute list in the inode.
>>   	 */
>>   	error = xfs_attr_try_sf_addname(dp, args);
>> -	if (error != -ENOSPC) {
>> -		error2 = xfs_trans_commit(args->trans);
>> -		args->trans = NULL;
>> -		return error ? error : error2;
>> -	}
>> +
>> +	/* Should only be 0, -EEXIST or -ENOSPC */
>> +	if (error != -ENOSPC)
>> +		return error;
>>   
>>   	/*
>>   	 * It won't fit in the shortform, transform to a leaf block.
>>   	 * GROT: another possible req'mt for a double-split btree op.
>>   	 */
>> -	error = xfs_attr_shortform_to_leaf(args, &leaf_bp);
>> +	error = xfs_attr_shortform_to_leaf(args, leaf_bp);
>>   	if (error)
>>   		return error;
>>   
>> @@ -296,102 +326,130 @@ xfs_attr_set_fmt(
>>   	 * concurrent AIL push cannot grab the half-baked leaf buffer
>>   	 * and run into problems 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;
>> -	}
>> +	xfs_trans_bhold(args->trans, *leaf_bp);
>>   
>> +	/*
>> +	 * We're still in XFS_DAS_UNINIT state here.  We've converted
>> +	 * the attr fork to leaf format and will restart with the leaf
>> +	 * add.
>> +	 */
>> +	dac->flags |= XFS_DAC_DEFER_FINISH;
>>   	return -EAGAIN;
>>   }
>>   
>>   /*
>>    * 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.
>>    */
>>   int
>> -xfs_attr_set_args(
>> -	struct xfs_da_args	*args)
>> +xfs_attr_set_iter(
>> +	struct xfs_delattr_context	*dac,
>> +	struct xfs_buf			**leaf_bp)
>>   {
>> -	struct xfs_inode	*dp = args->dp;
>> -	struct xfs_buf		*bp = NULL;
>> -	struct xfs_da_state     *state = NULL;
>> -	int			forkoff, error = 0;
>> +	struct xfs_da_args              *args = dac->da_args;
>> +	struct xfs_inode		*dp = args->dp;
>> +	struct xfs_buf			*bp = NULL;
>> +	int				forkoff, error = 0;
>>   
>> -	/*
>> -	 * 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.
>> -	 */
>> -	if (xfs_attr_is_shortform(dp)) {
>> -		error = xfs_attr_set_fmt(args);
>> -		if (error != -EAGAIN)
>> -			return error;
>> -	}
>> +	/* State machine switch */
>> +	switch (dac->dela_state) {
>> +	case XFS_DAS_UNINIT:
>> +		/*
>> +		 * If the fork is shortform, attempt to add the attr. If there
>> +		 * is no space, this converts to leaf format and returns
>> +		 * -EAGAIN with the leaf buffer held across the roll. The caller
>> +		 * will deal with a transaction roll error, but otherwise
>> +		 * release the hold once we return with a clean transaction.
>> +		 */
>> +		if (xfs_attr_is_shortform(dp))
>> +			return xfs_attr_set_fmt(dac, leaf_bp);
> 
> More post-series renaming nits:
> 
> These probably ought to be renamed xfs_attr_sf_addname or something to go
> with the _removename functions...
Sure, I'll throw that into the patch at the end
> 
> 
>> +		if (*leaf_bp != NULL) {
>> +			xfs_trans_bhold_release(args->trans, *leaf_bp);
>> +			*leaf_bp = NULL;
>> +		}
>>   
>> -	if (xfs_attr_is_leaf(dp)) {
>> -		error = xfs_attr_leaf_try_add(args, bp);
>> -		if (error == -ENOSPC) {
>> -			/*
>> -			 * Promote the attribute list to the Btree format.
>> -			 */
>> -			error = xfs_attr3_leaf_to_node(args);
>> -			if (error)
>> +		if (xfs_attr_is_leaf(dp)) {
>> +			error = xfs_attr_leaf_try_add(args, *leaf_bp);
>> +			if (error == -ENOSPC) {
>> +				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.
>> +				 *
>> +				 * At this point, we are still in
>> +				 * XFS_DAS_UNINIT, but when we come back, we'll
>> +				 * be a node, so we'll fall down into the node
>> +				 * handling code below
>> +				 */
>> +				dac->flags |= XFS_DAC_DEFER_FINISH;
>> +				return -EAGAIN;
>> +			} else 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);
>> +			dac->dela_state = XFS_DAS_FOUND_LBLK;
> 
> Can you lift just whole if block into a separate xfs_attr_leaf_addname
> function?  Especially since the state diagram indicates such a function
> and would result in this chunk losing two levels of indent?
> 
> I know, we got rid of it three patches ago, but at least the replacement
> would be shorter than the old version.
Hmm, I think others may have some opinion about that. There seemed to be 
much effort into getting all the "dela_state =" assignments into the 
same scope.

I can certainly explore that in another patch, but I would encourage 
adding that patch in the extended set, maybe in the fully delayed series 
which already has a few cleanup patches queued up in it.  That way 
delayed attrs and parent pointers can sort of progress in parrallel with 
the clean up rather than falling back into yet more refactoring.  My 
inkling is that this proposal will be met with a lot of opinion.

My plan here was to sort of get through this subseries, and then jump 
right into the next 12 patches of the extended set.  How about we add 
the extra patch there?  Maybe around near the end?

> 
>> +		} else {
>> +			error = xfs_attr_node_addname_find_attr(dac);
>>   			if (error)
>>   				return error;
>>   
>> -			/*
>> -			 * Commit the current trans (including the inode) and
>> -			 * start a new one.
>> -			 */
>> -			error = xfs_trans_roll_inode(&args->trans, dp);
>> +			error = xfs_attr_node_addname(dac);
>>   			if (error)
>>   				return error;
>>   
>> -			goto node;
>> -		} else if (error) {
>> -			return error;
>> +			dac->dela_state = XFS_DAS_FOUND_NBLK;
> 
> ... and then maybe this chunk can lose one level of indent?
yes but... same gripe with the dela = state assignment

> 
>>   		}
>> -
>> -		/*
>> -		 * 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;
>> -
>> +		return -EAGAIN;
>> +	case XFS_DAS_FOUND_LBLK:
>>   		/*
>>   		 * 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) {
>> -			error = xfs_attr_rmtval_set(args);
>> +
>> +		/* Open coded xfs_attr_rmtval_set without trans handling */
> 
> xfs_attr_rmtval_set has no callers, is that just sitting around waiting
> for the log item patchset coming next?
I think we forgot to clean it out.  Will remove.  Do you want that in a 
separate patch?

> 
> 
>> +		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;
>> +			}
>> +		}
>> +
>> +		/*
>> +		 * Repeat allocating remote blocks for the attr value until
>> +		 * blkcnt drops to zero.
>> +		 */
>> +		if (dac->blkcnt > 0) {
>> +			error = xfs_attr_rmtval_set_blk(dac);
>>   			if (error)
>>   				return error;
>> +			return -EAGAIN;
>>   		}
>>   
>> +		error = xfs_attr_rmtval_set_value(args);
>> +		if (error)
>> +			return error;
>> +
>> +		/*
>> +		 * If this is not a rename, clear the incomplete flag and we're
>> +		 * done.
>> +		 */
>>   		if (!(args->op_flags & XFS_DA_OP_RENAME)) {
>> -			/*
>> -			 * Added a "remote" value, just clear the incomplete
>> -			 *flag.
>> -			 */
>>   			if (args->rmtblkno > 0)
>>   				error = xfs_attr3_leaf_clearflag(args);
>> -
>>   			return error;
>>   		}
>>   
>> @@ -404,7 +462,6 @@ xfs_attr_set_args(
>>   		 * 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;
>> @@ -412,29 +469,37 @@ xfs_attr_set_args(
>>   		 * 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;
>> +	case XFS_DAS_FLIP_LFLAG:
>>   		/*
>>   		 * 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_LBLK:
>> +		/* Set state in case xfs_attr_rmtval_remove returns -EAGAIN */
>> +		dac->dela_state = XFS_DAS_RM_LBLK;
>>   		if (args->rmtblkno) {
>> -			error = xfs_attr_rmtval_invalidate(args);
>> +			error = __xfs_attr_rmtval_remove(dac);
>>   			if (error)
>>   				return error;
>>   
>> -			error = xfs_attr_rmtval_remove(args);
>> -			if (error)
>> -				return error;
>> +			dac->dela_state = XFS_DAS_RD_LEAF;
>> +			return -EAGAIN;
>>   		}
>>   
>> +		/* fallthrough */
>> +	case XFS_DAS_RD_LEAF:
>>   		/*
>> -		 * Read in the block containing the "old" attr, then remove the
>> -		 * "old" attr from that block (neat, huh!)
>> +		 * This is the last step for leaf format. Read the block with
>> +		 * the old attr, remove the old attr, check for shortform
>> +		 * conversion and return.
>>   		 */
>>   		error = xfs_attr3_leaf_read(args->trans, args->dp, args->blkno,
>>   					   &bp);
>> @@ -443,97 +508,116 @@ xfs_attr_set_args(
>>   
>>   		xfs_attr3_leaf_remove(bp, args);
>>   
>> -		/*
>> -		 * If the result is small enough, shrink it all into the inode.
>> -		 */
>>   		forkoff = xfs_attr_shortform_allfit(bp, dp);
>>   		if (forkoff)
>>   			error = xfs_attr3_leaf_to_shortform(bp, args, forkoff);
>>   			/* bp is gone due to xfs_da_shrink_inode */
>>   
>>   		return error;
>> -	}
>> -node:
>>   
>> +	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(dac);
>> +			if (error)
>> +				return error;
>> +		}
>>   
>> -	do {
>> -		error = xfs_attr_node_addname_find_attr(args, &state);
>> -		if (error)
>> -			return error;
>> -		error = xfs_attr_node_addname(args, state);
>> -	} while (error == -EAGAIN);
>> -	if (error)
>> -		return error;
>> +		/* fallthrough */
>> +	case XFS_DAS_ALLOC_NODE:
>> +		/*
>> +		 * 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.
>> +		 */
>> +		dac->dela_state = XFS_DAS_ALLOC_NODE;
>> +		if (args->rmtblkno > 0) {
>> +			if (dac->blkcnt > 0) {
>> +				error = xfs_attr_rmtval_set_blk(dac);
>> +				if (error)
>> +					return error;
>> +				return -EAGAIN;
>> +			}
>> +
>> +			error = xfs_attr_rmtval_set_value(args);
>> +			if (error)
>> +				return error;
>> +		}
>>   
>> -	/*
>> -	 * 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;
>> +		/*
>> +		 * 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 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) {
>> -		error = xfs_attr_rmtval_set(args);
>> +		/*
>> +		 * 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.
>> +		 */
>> +		error = xfs_attr3_leaf_flipflags(args);
>>   		if (error)
>> -			return error;
>> -	}
>> -
>> -	if (!(args->op_flags & XFS_DA_OP_RENAME)) {
>> +			goto out;
>>   		/*
>> -		 * Added a "remote" value, just clear the incomplete flag.
>> +		 * Commit the flag value change and start the next trans in
>> +		 * series
>>   		 */
>> -		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.
>> -	 */
>> -	error = xfs_attr3_leaf_flipflags(args);
>> -	if (error)
>> -		goto out;
>> -	/*
>> -	 * 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;
>>   
>> -	/*
>> -	 * Dismantle the "old" attribute/value pair by removing a "remote" value
>> -	 * (if it exists).
>> -	 */
>> -	xfs_attr_restore_rmt_blk(args);
>> +	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);
>>   
>> -	if (args->rmtblkno) {
>>   		error = xfs_attr_rmtval_invalidate(args);
>>   		if (error)
>>   			return error;
>>   
>> -		error = xfs_attr_rmtval_remove(args);
>> -		if (error)
>> -			return error;
>> -	}
>> +		/* fallthrough */
>> +	case XFS_DAS_RM_NBLK:
>> +		/* Set state in case xfs_attr_rmtval_remove returns -EAGAIN */
>> +		dac->dela_state = XFS_DAS_RM_NBLK;
>> +		if (args->rmtblkno) {
>> +			error = __xfs_attr_rmtval_remove(dac);
>> +			if (error)
>> +				return error;
>> +
>> +			dac->dela_state = XFS_DAS_CLR_FLAG;
>> +			return -EAGAIN;
>> +		}
>>   
>> -	error = xfs_attr_node_addname_clear_incomplete(args);
>> +		/* fallthrough */
>> +	case XFS_DAS_CLR_FLAG:
>> +		/*
>> +		 * The last state for node format. Look up the old attr and
>> +		 * remove it.
>> +		 */
>> +		error = xfs_attr_node_addname_clear_incomplete(dac);
>> +		break;
>> +	default:
>> +		ASSERT(dac->dela_state != XFS_DAS_RM_SHRINK);
> 
> How would we end up in RM_SHRINK?  Isn't that only set in the remove
> path?
Yes, I think that's the point of the assert tho.  This is a condition 
that should never happen, so assert that is not the case.  This was part 
of some psuedo code that was suggested earlier.  I do sort of worry 
about continueing to change the patch after it's earned the rvbs though?

> 
>> +		break;
>> +	}
>>   out:
>>   	return error;
>>   }
>>   
>> +
>>   /*
>>    * Return EEXIST if attr is found, or ENOATTR if not
>>    */
>> @@ -997,18 +1081,18 @@ xfs_attr_node_hasname(
>>   
>>   STATIC int
>>   xfs_attr_node_addname_find_attr(
>> -	struct xfs_da_args	*args,
>> -	struct xfs_da_state     **state)
>> +	struct xfs_delattr_context	*dac)
>>   {
>> -	int			retval;
>> +	struct xfs_da_args		*args = dac->da_args;
>> +	int				retval;
>>   
>>   	/*
>>   	 * Search to see if name already exists, and get back a pointer
>>   	 * to where it should go.
>>   	 */
>> -	retval = xfs_attr_node_hasname(args, state);
>> +	retval = xfs_attr_node_hasname(args, &dac->da_state);
>>   	if (retval != -ENOATTR && retval != -EEXIST)
>> -		goto error;
>> +		return retval;
>>   
>>   	if (retval == -ENOATTR && (args->attr_flags & XATTR_REPLACE))
>>   		goto error;
>> @@ -1034,8 +1118,8 @@ xfs_attr_node_addname_find_attr(
>>   
>>   	return 0;
>>   error:
>> -	if (*state)
>> -		xfs_da_state_free(*state);
>> +	if (dac->da_state)
>> +		xfs_da_state_free(dac->da_state);
>>   	return retval;
>>   }
>>   
>> @@ -1048,19 +1132,23 @@ xfs_attr_node_addname_find_attr(
>>    *
>>    * "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_da_state	*state)
>> +	struct xfs_delattr_context	*dac)
>>   {
>> -	struct xfs_da_state_blk	*blk;
>> -	struct xfs_inode	*dp;
>> -	int			error;
>> +	struct xfs_da_args		*args = dac->da_args;
>> +	struct xfs_da_state		*state = dac->da_state;
>> +	struct xfs_da_state_blk		*blk;
>> +	int				error;
>>   
>>   	trace_xfs_attr_node_addname(args);
>>   
>> -	dp = args->dp;
>>   	blk = &state->path.blk[state->path.active-1];
>>   	ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
>>   
>> @@ -1077,18 +1165,15 @@ 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.
>> +			 * Now that we have converted the leaf to a node, we can
>> +			 * roll the transaction, and try xfs_attr3_leaf_add
>> +			 * again on re-entry.  No need to set dela_state to do
>> +			 * this. dela_state is still unset by this function at
>> +			 * this point.
>>   			 */
>> -			error = xfs_trans_roll_inode(&args->trans, dp);
>> -			if (error)
>> -				goto out;
>> -
>> +			dac->flags |= XFS_DAC_DEFER_FINISH;
>>   			return -EAGAIN;
>>   		}
>>   
>> @@ -1101,9 +1186,7 @@ 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.
>> @@ -1120,8 +1203,9 @@ xfs_attr_node_addname(
>>   
>>   STATIC
>>   int xfs_attr_node_addname_clear_incomplete(
>> -	struct xfs_da_args		*args)
>> +	struct xfs_delattr_context	*dac)
>>   {
>> +	struct xfs_da_args		*args = dac->da_args;
>>   	struct xfs_da_state		*state = NULL;
>>   	struct xfs_da_state_blk		*blk;
>>   	int				retval = 0;
>> diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
>> index 32736d9..41ad5e8 100644
>> --- a/fs/xfs/libxfs/xfs_attr.h
>> +++ b/fs/xfs/libxfs/xfs_attr.h
>> @@ -164,6 +164,262 @@ struct xfs_attr_list_context {
>>    *              v
>>    *            done
>>    *
>> + *
>> + * Below is a state machine diagram for attr set operations.
>> + *
>> + * It seems the challenge with understanding this system comes from trying to
>> + * absorb the state machine all at once, when really one should only be looking
>> + * at it with in the context of a single function. Once a state sensitive
>> + * function is called, the idea is that it "takes ownership" of the
>> + * state machine. It isn't concerned with the states that may have belonged to
>> + * it's calling parent. Only the states relevant to itself or any other
>> + * subroutines there in. Once a calling function hands off the state machine to
>> + * a subroutine, it needs to respect the simple rule that it doesn't "own" the
>> + * state machine anymore, and it's the responsibility of that calling function
>> + * to propagate the -EAGAIN back up the call stack. Upon reentry, it is
>> + * committed to re-calling that subroutine until it returns something other than
>> + * -EAGAIN. Once that subroutine signals completion (by returning anything other
>> + * than -EAGAIN), the calling function can resume using the state machine.
>> + *
>> + *  xfs_attr_set_iter()
>> + *              │
>> + *              v
>> + *   ┌─y─ has an attr fork?
>> + *   │          |
>> + *   │          n
>> + *   │          |
>> + *   │          V
>> + *   │       add a fork
>> + *   │          │
>> + *   └──────────┤
>> + *              │
>> + *              V
>> + *   ┌─y─ is shortform?
>> + *   │          │
>> + *   │          V
>> + *   │   xfs_attr_set_fmt
>> + *   │          |
>> + *   │          V
>> + *   │ xfs_attr_try_sf_addname
>> + *   │          │
>> + *   │          V
>> + *   │      had enough ──y──> done
>> + *   │        space?
>> + *   n          │
> 
> About  ^^^ this line crawling down the left side of the flowchart:
> 
> How do we go from "y" -> "n" ?  Is that a clerical error?
Thats a typo, the "y" should be on the down arrow.  Will fix
> 
>> + *   │          n
>> + *   │          │
>> + *   │          V
>> + *   │   transform to leaf
>> + *   │          │
>> + *   │          V
>> + *   │   hold the leaf buffer
>> + *   │          │
>> + *   │          V
>> + *   │     return -EAGAIN
>> + *   │      Re-enter in
>> + *   │       leaf form
>> + *   │
>> + *   └─> release leaf buffer
>> + *          if needed
>> + *              │
>> + *              V
>> + *   ┌───n── fork has
>> + *   │      only 1 blk?
>> + *   │          │
>> + *   │          y
>> + *   │          │
>> + *   │          v
>> + *   │ xfs_attr_leaf_try_add()
>> + *   │          │
>> + *   │          v
>> + *   │      had enough ──────────────y─────────────┐
>> + *   │        space?                               │
>> + *   │          │                                  │
>> + *   │          n                                  │
>> + *   │          │                                  │
>> + *   │          v                                  │
>> + *   │    return -EAGAIN                           │
>> + *   │      re-enter in                            │
>> + *   │        node form                            │
>> + *   │          │                                  │
>> + *   └──────────┤                                  │
>> + *              │                                  │
>> + *              V                                  │
>> + * xfs_attr_node_addname_find_attr                 │
>> + *        determines if this                       │
>> + *       is create or rename                       │
>> + *     find space to store attr                    │
>> + *              │                                  │
>> + *              v                                  │
>> + *     xfs_attr_node_addname                       │
>> + *              │                                  │
>> + *              v                                  │
>> + *   fits in a node leaf? ────n─────┐              │
>> + *              │     ^             v              │
>> + *              │     │       single leaf node?    │
>> + *              │     │         │            │     │
>> + *              y     │         y            n     │
>> + *              │     │         │            │     │
>> + *              v     │         v            v     │
>> + *            update  │    grow the leaf  split if │
>> + *           hashvals └── return -EAGAIN   needed  │
>> + *              │         retry leaf add     │     │
>> + *              │           on reentry       │     │
>> + *              ├────────────────────────────┘     │
>> + *              │                                  │
>> + *              v                                  │
>> + *         need to alloc                           │
>> + *   ┌─y── or flip flag?                           │
>> + *   │          │                                  │
>> + *   │          n                                  │
>> + *   │          │                                  │
>> + *   │          v                                  │
>> + *   │         done                                │
>> + *   │                                             │
>> + *   │                                             │
>> + *   │         XFS_DAS_FOUND_LBLK <────────────────┘
>> + *   │                  │
>> + *   │                  V
>> + *   │        xfs_attr_leaf_addname()
>> + *   │                  │
>> + *   │                  v
>> + *   │      ┌──first time through?
>> + *   │      │          │
>> + *   │      │          y
>> + *   │      │          │
>> + *   │      n          v
>> + *   │      │    if we have rmt blks
>> + *   │      │    find space for them
>> + *   │      │          │
>> + *   │      └──────────┤
>> + *   │                 │
>> + *   │                 v
>> + *   │            still have
>> + *   │      ┌─n─ blks to alloc? <──┐
>> + *   │      │          │           │
>> + *   │      │          y           │
>> + *   │      │          │           │
>> + *   │      │          v           │
>> + *   │      │     alloc one blk    │
>> + *   │      │     return -EAGAIN ──┘
>> + *   │      │    re-enter with one
>> + *   │      │    less blk to alloc
>> + *   │      │
>> + *   │      │
>> + *   │      └───> set the rmt
>> + *   │               value
>> + *   │                 │
>> + *   │                 v
>> + *   │               was this
>> + *   │              a rename? ──n─┐
>> + *   │                 │          │
>> + *   │                 y          │
>> + *   │                 │          │
>> + *   │                 v          │
>> + *   │           flip incomplete  │
>> + *   │               flag         │
>> + *   │                 │          │
>> + *   │                 v          │
>> + *   │         XFS_DAS_FLIP_LFLAG │
>> + *   │                 │          │
>> + *   │                 v          │
>> + *   │          need to remove    │
>> + *   │              old bks? ──n──┤
>> + *   │                 │          │
>> + *   │                 y          │
>> + *   │                 │          │
>> + *   │                 V          │
>> + *   │               remove       │
>> + *   │        ┌───> old blks      │
>> + *   │        │        │          │
>> + *   │ XFS_DAS_RM_LBLK │          │
>> + *   │        ^        │          │
>> + *   │        │        v          │
>> + *   │        └──y── more to      │
>> + *   │              remove?       │
>> + *   │                 │          │
>> + *   │                 n          │
>> + *   │                 │          │
>> + *   │                 v          │
>> + *   │          XFS_DAS_RD_LEAF   │
>> + *   │                 │          │
>> + *   │                 v          │
>> + *   │            remove leaf     │
>> + *   │                 │          │
>> + *   │                 v          │
>> + *   │            shrink to sf    │
>> + *   │             if needed      │
>> + *   │                 │          │
>> + *   │                 v          │
>> + *   │                done <──────┘
>> + *   │
>> + *   └──────> XFS_DAS_FOUND_NBLK
>> + *                     │
>> + *                     v
>> + *       ┌─────n──  need to
>> + *       │        alloc blks?
>> + *       │             │
>> + *       │             y
>> + *       │             │
>> + *       │             v
>> + *       │        find space
>> + *       │             │
>> + *       │             v
>> + *       │  ┌─>XFS_DAS_ALLOC_NODE
>> + *       │  │          │
>> + *       │  │          v
>> + *       │  │      alloc blk
>> + *       │  │          │
>> + *       │  │          v
>> + *       │  └──y── need to alloc
>> + *       │         more blocks?
>> + *       │             │
>> + *       │             n
>> + *       │             │
>> + *       │             v
>> + *       │      set the rmt value
>> + *       │             │
>> + *       │             v
>> + *       │          was this
>> + *       └────────> a rename? ──n─┐
>> + *                     │          │
>> + *                     y          │
>> + *                     │          │
>> + *                     v          │
>> + *               flip incomplete  │
>> + *                   flag         │
>> + *                     │          │
>> + *                     v          │
>> + *             XFS_DAS_FLIP_NFLAG │
>> + *                     │          │
>> + *                     v          │
>> + *                 need to        │
>> + *               remove blks? ─n──┤
>> + *                     │          │
>> + *                     y          │
>> + *                     │          │
>> + *                     v          │
>> + *                   remove       │
>> + *        ┌────────> old blks     │
>> + *        │            │          │
>> + *  XFS_DAS_RM_NBLK    │          │
>> + *        ^            │          │
>> + *        │            v          │
>> + *        └──────y── more to      │
>> + *                   remove       │
>> + *                     │          │
>> + *                     n          │
>> + *                     │          │
>> + *                     v          │
>> + *              XFS_DAS_CLR_FLAG  │
>> + *                     │          │
>> + *                     v          │
>> + *                clear flags     │
>> + *                     │          │
>> + *                     ├──────────┘
>> + *                     │
>> + *                     v
>> + *                   done
>>    */
>>   
>>   /*
>> @@ -180,12 +436,22 @@ 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 */
>> +	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_RD_LEAF,	      /* Read in the new leaf */
>> +	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 */
>> +	XFS_DAS_CLR_FLAG,	      /* Clear incomplete flag */
>>   };
>>   
>>   /*
>>    * Defines for xfs_delattr_context.flags
>>    */
>>   #define XFS_DAC_DEFER_FINISH		0x01 /* finish the transaction */
>> +#define XFS_DAC_LEAF_ADDNAME_INIT	0x02 /* xfs_attr_leaf_addname init*/
>>   
>>   /*
>>    * Context used for keeping track of delayed attribute operations
>> @@ -193,6 +459,11 @@ 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;
>>   
>> @@ -220,7 +491,6 @@ 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 2f3c4cc..fc71f10 100644
>> --- a/fs/xfs/libxfs/xfs_attr_remote.c
>> +++ b/fs/xfs/libxfs/xfs_attr_remote.c
>> @@ -439,9 +439,9 @@ xfs_attr_rmtval_get(
>>   
>>   /*
>>    * Find a "hole" in the attribute address space large enough for us to drop the
>> - * new attribute's value into
>> + * new attributes 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);
> 
> Nit: indent two tabs for the second and third lines.
Sure, will fix.  Thanks for the review!

Allison

> 
> --D
> 
>> +	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.
>>    */
>> @@ -669,37 +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 && 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..8ad68d5 100644
>> --- a/fs/xfs/libxfs/xfs_attr_remote.h
>> +++ b/fs/xfs/libxfs/xfs_attr_remote.h
>> @@ -10,9 +10,12 @@ int xfs_attr3_rmt_blocks(struct xfs_mount *mp, int attrlen);
>>   
>>   int xfs_attr_rmtval_get(struct xfs_da_args *args);
>>   int xfs_attr_rmtval_set(struct xfs_da_args *args);
>> -int xfs_attr_rmtval_remove(struct xfs_da_args *args);
>>   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 3c1c830..96f93a7 100644
>> --- a/fs/xfs/xfs_trace.h
>> +++ b/fs/xfs/xfs_trace.h
>> @@ -1943,7 +1943,6 @@ 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
>>

Re: [PATCH RESEND v18 11/11] xfs: Add delay ready attr set routines

[Darrick J. Wong]

On Fri, May 14, 2021 at 10:41:40PM -0700, Allison Henderson wrote:
> 
> 
> On 5/13/21 6:14 PM, Darrick J. Wong wrote:
> > On Wed, May 12, 2021 at 09:14:08AM -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_find_space 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>
> > > Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
> > > Reviewed-by: Darrick J. Wong <djwong@kernel.org>
> > 
> > Heh, I already reviewed this, but I see a few things that could be
> > cleaned up a bit as a followon...
> > 
> > > Reviewed-by: Brian Foster <bfoster@redhat.com>
> > > ---
> > >   fs/xfs/libxfs/xfs_attr.c        | 450 ++++++++++++++++++++++++----------------
> > >   fs/xfs/libxfs/xfs_attr.h        | 272 +++++++++++++++++++++++-
> > >   fs/xfs/libxfs/xfs_attr_remote.c | 100 ++++++---
> > >   fs/xfs/libxfs/xfs_attr_remote.h |   5 +-
> > >   fs/xfs/xfs_trace.h              |   1 -
> > >   5 files changed, 608 insertions(+), 220 deletions(-)
> > > 
> > > diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> > > index a91fff6..4096418 100644
> > > --- a/fs/xfs/libxfs/xfs_attr.c
> > > +++ b/fs/xfs/libxfs/xfs_attr.c
> > > @@ -53,15 +53,16 @@ STATIC int xfs_attr_leaf_try_add(struct xfs_da_args *args, struct xfs_buf *bp);
> > >    */
> > >   STATIC int xfs_attr_node_get(xfs_da_args_t *args);
> > >   STATIC void xfs_attr_restore_rmt_blk(struct xfs_da_args *args);
> > > -STATIC int xfs_attr_node_addname(struct xfs_da_args *args,
> > > -				 struct xfs_da_state *state);
> > > -STATIC int xfs_attr_node_addname_find_attr(struct xfs_da_args *args,
> > > -				 struct xfs_da_state **state);
> > > -STATIC int xfs_attr_node_addname_clear_incomplete(struct xfs_da_args *args);
> > > +STATIC int xfs_attr_node_addname(struct xfs_delattr_context *dac);
> > > +STATIC int xfs_attr_node_addname_find_attr(struct xfs_delattr_context *dac);
> > > +STATIC int xfs_attr_node_addname_clear_incomplete(
> > > +				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_set_iter(struct xfs_delattr_context *dac,
> > > +			     struct xfs_buf **leaf_bp);
> > >   int
> > >   xfs_inode_hasattr(
> > > @@ -244,7 +245,7 @@ xfs_attr_is_shortform(
> > >    * Checks to see if a delayed attribute transaction should be rolled.  If so,
> > >    * transaction is finished or rolled as needed.
> > >    */
> > > -int
> > > +STATIC int
> > >   xfs_attr_trans_roll(
> > >   	struct xfs_delattr_context	*dac)
> > >   {
> > > @@ -265,29 +266,58 @@ xfs_attr_trans_roll(
> > >   	return error;
> > >   }
> > > +/*
> > > + * Set the attribute specified in @args.
> > > + */
> > > +int
> > > +xfs_attr_set_args(
> > > +	struct xfs_da_args		*args)
> > > +{
> > > +	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) {
> > > +			if (leaf_bp)
> > > +				xfs_trans_brelse(args->trans, leaf_bp);
> > > +			return error;
> > > +		}
> > > +	} while (true);
> > > +
> > > +	return error;
> > > +}
> > > +
> > >   STATIC int
> > >   xfs_attr_set_fmt(
> > > -	struct xfs_da_args	*args)
> > > +	struct xfs_delattr_context	*dac,
> > > +	struct xfs_buf			**leaf_bp)
> > >   {
> > > -	struct xfs_buf          *leaf_bp = NULL;
> > > -	struct xfs_inode	*dp = args->dp;
> > > -	int			error2, error = 0;
> > > +	struct xfs_da_args		*args = dac->da_args;
> > > +	struct xfs_inode		*dp = args->dp;
> > > +	int				error = 0;
> > >   	/*
> > >   	 * Try to add the attr to the attribute list in the inode.
> > >   	 */
> > >   	error = xfs_attr_try_sf_addname(dp, args);
> > > -	if (error != -ENOSPC) {
> > > -		error2 = xfs_trans_commit(args->trans);
> > > -		args->trans = NULL;
> > > -		return error ? error : error2;
> > > -	}
> > > +
> > > +	/* Should only be 0, -EEXIST or -ENOSPC */
> > > +	if (error != -ENOSPC)
> > > +		return error;
> > >   	/*
> > >   	 * It won't fit in the shortform, transform to a leaf block.
> > >   	 * GROT: another possible req'mt for a double-split btree op.
> > >   	 */
> > > -	error = xfs_attr_shortform_to_leaf(args, &leaf_bp);
> > > +	error = xfs_attr_shortform_to_leaf(args, leaf_bp);
> > >   	if (error)
> > >   		return error;
> > > @@ -296,102 +326,130 @@ xfs_attr_set_fmt(
> > >   	 * concurrent AIL push cannot grab the half-baked leaf buffer
> > >   	 * and run into problems 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;
> > > -	}
> > > +	xfs_trans_bhold(args->trans, *leaf_bp);
> > > +	/*
> > > +	 * We're still in XFS_DAS_UNINIT state here.  We've converted
> > > +	 * the attr fork to leaf format and will restart with the leaf
> > > +	 * add.
> > > +	 */
> > > +	dac->flags |= XFS_DAC_DEFER_FINISH;
> > >   	return -EAGAIN;
> > >   }
> > >   /*
> > >    * 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.
> > >    */
> > >   int
> > > -xfs_attr_set_args(
> > > -	struct xfs_da_args	*args)
> > > +xfs_attr_set_iter(
> > > +	struct xfs_delattr_context	*dac,
> > > +	struct xfs_buf			**leaf_bp)
> > >   {
> > > -	struct xfs_inode	*dp = args->dp;
> > > -	struct xfs_buf		*bp = NULL;
> > > -	struct xfs_da_state     *state = NULL;
> > > -	int			forkoff, error = 0;
> > > +	struct xfs_da_args              *args = dac->da_args;
> > > +	struct xfs_inode		*dp = args->dp;
> > > +	struct xfs_buf			*bp = NULL;
> > > +	int				forkoff, error = 0;
> > > -	/*
> > > -	 * 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.
> > > -	 */
> > > -	if (xfs_attr_is_shortform(dp)) {
> > > -		error = xfs_attr_set_fmt(args);
> > > -		if (error != -EAGAIN)
> > > -			return error;
> > > -	}
> > > +	/* State machine switch */
> > > +	switch (dac->dela_state) {
> > > +	case XFS_DAS_UNINIT:
> > > +		/*
> > > +		 * If the fork is shortform, attempt to add the attr. If there
> > > +		 * is no space, this converts to leaf format and returns
> > > +		 * -EAGAIN with the leaf buffer held across the roll. The caller
> > > +		 * will deal with a transaction roll error, but otherwise
> > > +		 * release the hold once we return with a clean transaction.
> > > +		 */
> > > +		if (xfs_attr_is_shortform(dp))
> > > +			return xfs_attr_set_fmt(dac, leaf_bp);
> > 
> > More post-series renaming nits:
> > 
> > These probably ought to be renamed xfs_attr_sf_addname or something to go
> > with the _removename functions...
> Sure, I'll throw that into the patch at the end
> > 
> > 
> > > +		if (*leaf_bp != NULL) {
> > > +			xfs_trans_bhold_release(args->trans, *leaf_bp);
> > > +			*leaf_bp = NULL;
> > > +		}
> > > -	if (xfs_attr_is_leaf(dp)) {
> > > -		error = xfs_attr_leaf_try_add(args, bp);
> > > -		if (error == -ENOSPC) {
> > > -			/*
> > > -			 * Promote the attribute list to the Btree format.
> > > -			 */
> > > -			error = xfs_attr3_leaf_to_node(args);
> > > -			if (error)
> > > +		if (xfs_attr_is_leaf(dp)) {
> > > +			error = xfs_attr_leaf_try_add(args, *leaf_bp);
> > > +			if (error == -ENOSPC) {
> > > +				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.
> > > +				 *
> > > +				 * At this point, we are still in
> > > +				 * XFS_DAS_UNINIT, but when we come back, we'll
> > > +				 * be a node, so we'll fall down into the node
> > > +				 * handling code below
> > > +				 */
> > > +				dac->flags |= XFS_DAC_DEFER_FINISH;
> > > +				return -EAGAIN;
> > > +			} else 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);
> > > +			dac->dela_state = XFS_DAS_FOUND_LBLK;
> > 
> > Can you lift just whole if block into a separate xfs_attr_leaf_addname
> > function?  Especially since the state diagram indicates such a function
> > and would result in this chunk losing two levels of indent?
> > 
> > I know, we got rid of it three patches ago, but at least the replacement
> > would be shorter than the old version.
> Hmm, I think others may have some opinion about that. There seemed to be
> much effort into getting all the "dela_state =" assignments into the same
> scope.
> 
> I can certainly explore that in another patch, but I would encourage adding
> that patch in the extended set, maybe in the fully delayed series which
> already has a few cleanup patches queued up in it.  That way delayed attrs
> and parent pointers can sort of progress in parrallel with the clean up
> rather than falling back into yet more refactoring.  My inkling is that this
> proposal will be met with a lot of opinion.
> 
> My plan here was to sort of get through this subseries, and then jump right
> into the next 12 patches of the extended set.  How about we add the extra
> patch there?  Maybe around near the end?

Ok, that suits me just fine. :)

> 
> > 
> > > +		} else {
> > > +			error = xfs_attr_node_addname_find_attr(dac);
> > >   			if (error)
> > >   				return error;
> > > -			/*
> > > -			 * Commit the current trans (including the inode) and
> > > -			 * start a new one.
> > > -			 */
> > > -			error = xfs_trans_roll_inode(&args->trans, dp);
> > > +			error = xfs_attr_node_addname(dac);
> > >   			if (error)
> > >   				return error;
> > > -			goto node;
> > > -		} else if (error) {
> > > -			return error;
> > > +			dac->dela_state = XFS_DAS_FOUND_NBLK;
> > 
> > ... and then maybe this chunk can lose one level of indent?
> yes but... same gripe with the dela = state assignment
> 
> > 
> > >   		}
> > > -
> > > -		/*
> > > -		 * 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;
> > > -
> > > +		return -EAGAIN;
> > > +	case XFS_DAS_FOUND_LBLK:
> > >   		/*
> > >   		 * 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) {
> > > -			error = xfs_attr_rmtval_set(args);
> > > +
> > > +		/* Open coded xfs_attr_rmtval_set without trans handling */
> > 
> > xfs_attr_rmtval_set has no callers, is that just sitting around waiting
> > for the log item patchset coming next?
> I think we forgot to clean it out.  Will remove.  Do you want that in a
> separate patch?

Yes, please.

> > 
> > 
> > > +		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;
> > > +			}
> > > +		}
> > > +
> > > +		/*
> > > +		 * Repeat allocating remote blocks for the attr value until
> > > +		 * blkcnt drops to zero.
> > > +		 */
> > > +		if (dac->blkcnt > 0) {
> > > +			error = xfs_attr_rmtval_set_blk(dac);
> > >   			if (error)
> > >   				return error;
> > > +			return -EAGAIN;
> > >   		}
> > > +		error = xfs_attr_rmtval_set_value(args);
> > > +		if (error)
> > > +			return error;
> > > +
> > > +		/*
> > > +		 * If this is not a rename, clear the incomplete flag and we're
> > > +		 * done.
> > > +		 */
> > >   		if (!(args->op_flags & XFS_DA_OP_RENAME)) {
> > > -			/*
> > > -			 * Added a "remote" value, just clear the incomplete
> > > -			 *flag.
> > > -			 */
> > >   			if (args->rmtblkno > 0)
> > >   				error = xfs_attr3_leaf_clearflag(args);
> > > -
> > >   			return error;
> > >   		}
> > > @@ -404,7 +462,6 @@ xfs_attr_set_args(
> > >   		 * 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;
> > > @@ -412,29 +469,37 @@ xfs_attr_set_args(
> > >   		 * 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;
> > > +	case XFS_DAS_FLIP_LFLAG:
> > >   		/*
> > >   		 * 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_LBLK:
> > > +		/* Set state in case xfs_attr_rmtval_remove returns -EAGAIN */
> > > +		dac->dela_state = XFS_DAS_RM_LBLK;
> > >   		if (args->rmtblkno) {
> > > -			error = xfs_attr_rmtval_invalidate(args);
> > > +			error = __xfs_attr_rmtval_remove(dac);
> > >   			if (error)
> > >   				return error;
> > > -			error = xfs_attr_rmtval_remove(args);
> > > -			if (error)
> > > -				return error;
> > > +			dac->dela_state = XFS_DAS_RD_LEAF;
> > > +			return -EAGAIN;
> > >   		}
> > > +		/* fallthrough */
> > > +	case XFS_DAS_RD_LEAF:
> > >   		/*
> > > -		 * Read in the block containing the "old" attr, then remove the
> > > -		 * "old" attr from that block (neat, huh!)
> > > +		 * This is the last step for leaf format. Read the block with
> > > +		 * the old attr, remove the old attr, check for shortform
> > > +		 * conversion and return.
> > >   		 */
> > >   		error = xfs_attr3_leaf_read(args->trans, args->dp, args->blkno,
> > >   					   &bp);
> > > @@ -443,97 +508,116 @@ xfs_attr_set_args(
> > >   		xfs_attr3_leaf_remove(bp, args);
> > > -		/*
> > > -		 * If the result is small enough, shrink it all into the inode.
> > > -		 */
> > >   		forkoff = xfs_attr_shortform_allfit(bp, dp);
> > >   		if (forkoff)
> > >   			error = xfs_attr3_leaf_to_shortform(bp, args, forkoff);
> > >   			/* bp is gone due to xfs_da_shrink_inode */
> > >   		return error;
> > > -	}
> > > -node:
> > > +	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(dac);
> > > +			if (error)
> > > +				return error;
> > > +		}
> > > -	do {
> > > -		error = xfs_attr_node_addname_find_attr(args, &state);
> > > -		if (error)
> > > -			return error;
> > > -		error = xfs_attr_node_addname(args, state);
> > > -	} while (error == -EAGAIN);
> > > -	if (error)
> > > -		return error;
> > > +		/* fallthrough */
> > > +	case XFS_DAS_ALLOC_NODE:
> > > +		/*
> > > +		 * 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.
> > > +		 */
> > > +		dac->dela_state = XFS_DAS_ALLOC_NODE;
> > > +		if (args->rmtblkno > 0) {
> > > +			if (dac->blkcnt > 0) {
> > > +				error = xfs_attr_rmtval_set_blk(dac);
> > > +				if (error)
> > > +					return error;
> > > +				return -EAGAIN;
> > > +			}
> > > +
> > > +			error = xfs_attr_rmtval_set_value(args);
> > > +			if (error)
> > > +				return error;
> > > +		}
> > > -	/*
> > > -	 * 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;
> > > +		/*
> > > +		 * 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 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) {
> > > -		error = xfs_attr_rmtval_set(args);
> > > +		/*
> > > +		 * 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.
> > > +		 */
> > > +		error = xfs_attr3_leaf_flipflags(args);
> > >   		if (error)
> > > -			return error;
> > > -	}
> > > -
> > > -	if (!(args->op_flags & XFS_DA_OP_RENAME)) {
> > > +			goto out;
> > >   		/*
> > > -		 * Added a "remote" value, just clear the incomplete flag.
> > > +		 * Commit the flag value change and start the next trans in
> > > +		 * series
> > >   		 */
> > > -		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.
> > > -	 */
> > > -	error = xfs_attr3_leaf_flipflags(args);
> > > -	if (error)
> > > -		goto out;
> > > -	/*
> > > -	 * 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;
> > > -	/*
> > > -	 * Dismantle the "old" attribute/value pair by removing a "remote" value
> > > -	 * (if it exists).
> > > -	 */
> > > -	xfs_attr_restore_rmt_blk(args);
> > > +	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);
> > > -	if (args->rmtblkno) {
> > >   		error = xfs_attr_rmtval_invalidate(args);
> > >   		if (error)
> > >   			return error;
> > > -		error = xfs_attr_rmtval_remove(args);
> > > -		if (error)
> > > -			return error;
> > > -	}
> > > +		/* fallthrough */
> > > +	case XFS_DAS_RM_NBLK:
> > > +		/* Set state in case xfs_attr_rmtval_remove returns -EAGAIN */
> > > +		dac->dela_state = XFS_DAS_RM_NBLK;
> > > +		if (args->rmtblkno) {
> > > +			error = __xfs_attr_rmtval_remove(dac);
> > > +			if (error)
> > > +				return error;
> > > +
> > > +			dac->dela_state = XFS_DAS_CLR_FLAG;
> > > +			return -EAGAIN;
> > > +		}
> > > -	error = xfs_attr_node_addname_clear_incomplete(args);
> > > +		/* fallthrough */
> > > +	case XFS_DAS_CLR_FLAG:
> > > +		/*
> > > +		 * The last state for node format. Look up the old attr and
> > > +		 * remove it.
> > > +		 */
> > > +		error = xfs_attr_node_addname_clear_incomplete(dac);
> > > +		break;
> > > +	default:
> > > +		ASSERT(dac->dela_state != XFS_DAS_RM_SHRINK);
> > 
> > How would we end up in RM_SHRINK?  Isn't that only set in the remove
> > path?
> Yes, I think that's the point of the assert tho.  This is a condition that
> should never happen, so assert that is not the case.  This was part of some
> psuedo code that was suggested earlier.  I do sort of worry about
> continueing to change the patch after it's earned the rvbs though?

Yet another to add to the cleaning series, then.

(Don't drop the RVBs on this one just to fix an assert)

--D

> 
> > 
> > > +		break;
> > > +	}
> > >   out:
> > >   	return error;
> > >   }
> > > +
> > >   /*
> > >    * Return EEXIST if attr is found, or ENOATTR if not
> > >    */
> > > @@ -997,18 +1081,18 @@ xfs_attr_node_hasname(
> > >   STATIC int
> > >   xfs_attr_node_addname_find_attr(
> > > -	struct xfs_da_args	*args,
> > > -	struct xfs_da_state     **state)
> > > +	struct xfs_delattr_context	*dac)
> > >   {
> > > -	int			retval;
> > > +	struct xfs_da_args		*args = dac->da_args;
> > > +	int				retval;
> > >   	/*
> > >   	 * Search to see if name already exists, and get back a pointer
> > >   	 * to where it should go.
> > >   	 */
> > > -	retval = xfs_attr_node_hasname(args, state);
> > > +	retval = xfs_attr_node_hasname(args, &dac->da_state);
> > >   	if (retval != -ENOATTR && retval != -EEXIST)
> > > -		goto error;
> > > +		return retval;
> > >   	if (retval == -ENOATTR && (args->attr_flags & XATTR_REPLACE))
> > >   		goto error;
> > > @@ -1034,8 +1118,8 @@ xfs_attr_node_addname_find_attr(
> > >   	return 0;
> > >   error:
> > > -	if (*state)
> > > -		xfs_da_state_free(*state);
> > > +	if (dac->da_state)
> > > +		xfs_da_state_free(dac->da_state);
> > >   	return retval;
> > >   }
> > > @@ -1048,19 +1132,23 @@ xfs_attr_node_addname_find_attr(
> > >    *
> > >    * "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_da_state	*state)
> > > +	struct xfs_delattr_context	*dac)
> > >   {
> > > -	struct xfs_da_state_blk	*blk;
> > > -	struct xfs_inode	*dp;
> > > -	int			error;
> > > +	struct xfs_da_args		*args = dac->da_args;
> > > +	struct xfs_da_state		*state = dac->da_state;
> > > +	struct xfs_da_state_blk		*blk;
> > > +	int				error;
> > >   	trace_xfs_attr_node_addname(args);
> > > -	dp = args->dp;
> > >   	blk = &state->path.blk[state->path.active-1];
> > >   	ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
> > > @@ -1077,18 +1165,15 @@ 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.
> > > +			 * Now that we have converted the leaf to a node, we can
> > > +			 * roll the transaction, and try xfs_attr3_leaf_add
> > > +			 * again on re-entry.  No need to set dela_state to do
> > > +			 * this. dela_state is still unset by this function at
> > > +			 * this point.
> > >   			 */
> > > -			error = xfs_trans_roll_inode(&args->trans, dp);
> > > -			if (error)
> > > -				goto out;
> > > -
> > > +			dac->flags |= XFS_DAC_DEFER_FINISH;
> > >   			return -EAGAIN;
> > >   		}
> > > @@ -1101,9 +1186,7 @@ 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.
> > > @@ -1120,8 +1203,9 @@ xfs_attr_node_addname(
> > >   STATIC
> > >   int xfs_attr_node_addname_clear_incomplete(
> > > -	struct xfs_da_args		*args)
> > > +	struct xfs_delattr_context	*dac)
> > >   {
> > > +	struct xfs_da_args		*args = dac->da_args;
> > >   	struct xfs_da_state		*state = NULL;
> > >   	struct xfs_da_state_blk		*blk;
> > >   	int				retval = 0;
> > > diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
> > > index 32736d9..41ad5e8 100644
> > > --- a/fs/xfs/libxfs/xfs_attr.h
> > > +++ b/fs/xfs/libxfs/xfs_attr.h
> > > @@ -164,6 +164,262 @@ struct xfs_attr_list_context {
> > >    *              v
> > >    *            done
> > >    *
> > > + *
> > > + * Below is a state machine diagram for attr set operations.
> > > + *
> > > + * It seems the challenge with understanding this system comes from trying to
> > > + * absorb the state machine all at once, when really one should only be looking
> > > + * at it with in the context of a single function. Once a state sensitive
> > > + * function is called, the idea is that it "takes ownership" of the
> > > + * state machine. It isn't concerned with the states that may have belonged to
> > > + * it's calling parent. Only the states relevant to itself or any other
> > > + * subroutines there in. Once a calling function hands off the state machine to
> > > + * a subroutine, it needs to respect the simple rule that it doesn't "own" the
> > > + * state machine anymore, and it's the responsibility of that calling function
> > > + * to propagate the -EAGAIN back up the call stack. Upon reentry, it is
> > > + * committed to re-calling that subroutine until it returns something other than
> > > + * -EAGAIN. Once that subroutine signals completion (by returning anything other
> > > + * than -EAGAIN), the calling function can resume using the state machine.
> > > + *
> > > + *  xfs_attr_set_iter()
> > > + *              │
> > > + *              v
> > > + *   ┌─y─ has an attr fork?
> > > + *   │          |
> > > + *   │          n
> > > + *   │          |
> > > + *   │          V
> > > + *   │       add a fork
> > > + *   │          │
> > > + *   └──────────┤
> > > + *              │
> > > + *              V
> > > + *   ┌─y─ is shortform?
> > > + *   │          │
> > > + *   │          V
> > > + *   │   xfs_attr_set_fmt
> > > + *   │          |
> > > + *   │          V
> > > + *   │ xfs_attr_try_sf_addname
> > > + *   │          │
> > > + *   │          V
> > > + *   │      had enough ──y──> done
> > > + *   │        space?
> > > + *   n          │
> > 
> > About  ^^^ this line crawling down the left side of the flowchart:
> > 
> > How do we go from "y" -> "n" ?  Is that a clerical error?
> Thats a typo, the "y" should be on the down arrow.  Will fix
> > 
> > > + *   │          n
> > > + *   │          │
> > > + *   │          V
> > > + *   │   transform to leaf
> > > + *   │          │
> > > + *   │          V
> > > + *   │   hold the leaf buffer
> > > + *   │          │
> > > + *   │          V
> > > + *   │     return -EAGAIN
> > > + *   │      Re-enter in
> > > + *   │       leaf form
> > > + *   │
> > > + *   └─> release leaf buffer
> > > + *          if needed
> > > + *              │
> > > + *              V
> > > + *   ┌───n── fork has
> > > + *   │      only 1 blk?
> > > + *   │          │
> > > + *   │          y
> > > + *   │          │
> > > + *   │          v
> > > + *   │ xfs_attr_leaf_try_add()
> > > + *   │          │
> > > + *   │          v
> > > + *   │      had enough ──────────────y─────────────┐
> > > + *   │        space?                               │
> > > + *   │          │                                  │
> > > + *   │          n                                  │
> > > + *   │          │                                  │
> > > + *   │          v                                  │
> > > + *   │    return -EAGAIN                           │
> > > + *   │      re-enter in                            │
> > > + *   │        node form                            │
> > > + *   │          │                                  │
> > > + *   └──────────┤                                  │
> > > + *              │                                  │
> > > + *              V                                  │
> > > + * xfs_attr_node_addname_find_attr                 │
> > > + *        determines if this                       │
> > > + *       is create or rename                       │
> > > + *     find space to store attr                    │
> > > + *              │                                  │
> > > + *              v                                  │
> > > + *     xfs_attr_node_addname                       │
> > > + *              │                                  │
> > > + *              v                                  │
> > > + *   fits in a node leaf? ────n─────┐              │
> > > + *              │     ^             v              │
> > > + *              │     │       single leaf node?    │
> > > + *              │     │         │            │     │
> > > + *              y     │         y            n     │
> > > + *              │     │         │            │     │
> > > + *              v     │         v            v     │
> > > + *            update  │    grow the leaf  split if │
> > > + *           hashvals └── return -EAGAIN   needed  │
> > > + *              │         retry leaf add     │     │
> > > + *              │           on reentry       │     │
> > > + *              ├────────────────────────────┘     │
> > > + *              │                                  │
> > > + *              v                                  │
> > > + *         need to alloc                           │
> > > + *   ┌─y── or flip flag?                           │
> > > + *   │          │                                  │
> > > + *   │          n                                  │
> > > + *   │          │                                  │
> > > + *   │          v                                  │
> > > + *   │         done                                │
> > > + *   │                                             │
> > > + *   │                                             │
> > > + *   │         XFS_DAS_FOUND_LBLK <────────────────┘
> > > + *   │                  │
> > > + *   │                  V
> > > + *   │        xfs_attr_leaf_addname()
> > > + *   │                  │
> > > + *   │                  v
> > > + *   │      ┌──first time through?
> > > + *   │      │          │
> > > + *   │      │          y
> > > + *   │      │          │
> > > + *   │      n          v
> > > + *   │      │    if we have rmt blks
> > > + *   │      │    find space for them
> > > + *   │      │          │
> > > + *   │      └──────────┤
> > > + *   │                 │
> > > + *   │                 v
> > > + *   │            still have
> > > + *   │      ┌─n─ blks to alloc? <──┐
> > > + *   │      │          │           │
> > > + *   │      │          y           │
> > > + *   │      │          │           │
> > > + *   │      │          v           │
> > > + *   │      │     alloc one blk    │
> > > + *   │      │     return -EAGAIN ──┘
> > > + *   │      │    re-enter with one
> > > + *   │      │    less blk to alloc
> > > + *   │      │
> > > + *   │      │
> > > + *   │      └───> set the rmt
> > > + *   │               value
> > > + *   │                 │
> > > + *   │                 v
> > > + *   │               was this
> > > + *   │              a rename? ──n─┐
> > > + *   │                 │          │
> > > + *   │                 y          │
> > > + *   │                 │          │
> > > + *   │                 v          │
> > > + *   │           flip incomplete  │
> > > + *   │               flag         │
> > > + *   │                 │          │
> > > + *   │                 v          │
> > > + *   │         XFS_DAS_FLIP_LFLAG │
> > > + *   │                 │          │
> > > + *   │                 v          │
> > > + *   │          need to remove    │
> > > + *   │              old bks? ──n──┤
> > > + *   │                 │          │
> > > + *   │                 y          │
> > > + *   │                 │          │
> > > + *   │                 V          │
> > > + *   │               remove       │
> > > + *   │        ┌───> old blks      │
> > > + *   │        │        │          │
> > > + *   │ XFS_DAS_RM_LBLK │          │
> > > + *   │        ^        │          │
> > > + *   │        │        v          │
> > > + *   │        └──y── more to      │
> > > + *   │              remove?       │
> > > + *   │                 │          │
> > > + *   │                 n          │
> > > + *   │                 │          │
> > > + *   │                 v          │
> > > + *   │          XFS_DAS_RD_LEAF   │
> > > + *   │                 │          │
> > > + *   │                 v          │
> > > + *   │            remove leaf     │
> > > + *   │                 │          │
> > > + *   │                 v          │
> > > + *   │            shrink to sf    │
> > > + *   │             if needed      │
> > > + *   │                 │          │
> > > + *   │                 v          │
> > > + *   │                done <──────┘
> > > + *   │
> > > + *   └──────> XFS_DAS_FOUND_NBLK
> > > + *                     │
> > > + *                     v
> > > + *       ┌─────n──  need to
> > > + *       │        alloc blks?
> > > + *       │             │
> > > + *       │             y
> > > + *       │             │
> > > + *       │             v
> > > + *       │        find space
> > > + *       │             │
> > > + *       │             v
> > > + *       │  ┌─>XFS_DAS_ALLOC_NODE
> > > + *       │  │          │
> > > + *       │  │          v
> > > + *       │  │      alloc blk
> > > + *       │  │          │
> > > + *       │  │          v
> > > + *       │  └──y── need to alloc
> > > + *       │         more blocks?
> > > + *       │             │
> > > + *       │             n
> > > + *       │             │
> > > + *       │             v
> > > + *       │      set the rmt value
> > > + *       │             │
> > > + *       │             v
> > > + *       │          was this
> > > + *       └────────> a rename? ──n─┐
> > > + *                     │          │
> > > + *                     y          │
> > > + *                     │          │
> > > + *                     v          │
> > > + *               flip incomplete  │
> > > + *                   flag         │
> > > + *                     │          │
> > > + *                     v          │
> > > + *             XFS_DAS_FLIP_NFLAG │
> > > + *                     │          │
> > > + *                     v          │
> > > + *                 need to        │
> > > + *               remove blks? ─n──┤
> > > + *                     │          │
> > > + *                     y          │
> > > + *                     │          │
> > > + *                     v          │
> > > + *                   remove       │
> > > + *        ┌────────> old blks     │
> > > + *        │            │          │
> > > + *  XFS_DAS_RM_NBLK    │          │
> > > + *        ^            │          │
> > > + *        │            v          │
> > > + *        └──────y── more to      │
> > > + *                   remove       │
> > > + *                     │          │
> > > + *                     n          │
> > > + *                     │          │
> > > + *                     v          │
> > > + *              XFS_DAS_CLR_FLAG  │
> > > + *                     │          │
> > > + *                     v          │
> > > + *                clear flags     │
> > > + *                     │          │
> > > + *                     ├──────────┘
> > > + *                     │
> > > + *                     v
> > > + *                   done
> > >    */
> > >   /*
> > > @@ -180,12 +436,22 @@ 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 */
> > > +	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_RD_LEAF,	      /* Read in the new leaf */
> > > +	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 */
> > > +	XFS_DAS_CLR_FLAG,	      /* Clear incomplete flag */
> > >   };
> > >   /*
> > >    * Defines for xfs_delattr_context.flags
> > >    */
> > >   #define XFS_DAC_DEFER_FINISH		0x01 /* finish the transaction */
> > > +#define XFS_DAC_LEAF_ADDNAME_INIT	0x02 /* xfs_attr_leaf_addname init*/
> > >   /*
> > >    * Context used for keeping track of delayed attribute operations
> > > @@ -193,6 +459,11 @@ 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;
> > > @@ -220,7 +491,6 @@ 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 2f3c4cc..fc71f10 100644
> > > --- a/fs/xfs/libxfs/xfs_attr_remote.c
> > > +++ b/fs/xfs/libxfs/xfs_attr_remote.c
> > > @@ -439,9 +439,9 @@ xfs_attr_rmtval_get(
> > >   /*
> > >    * Find a "hole" in the attribute address space large enough for us to drop the
> > > - * new attribute's value into
> > > + * new attributes 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);
> > 
> > Nit: indent two tabs for the second and third lines.
> Sure, will fix.  Thanks for the review!
> 
> Allison
> 
> > 
> > --D
> > 
> > > +	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.
> > >    */
> > > @@ -669,37 +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 && 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..8ad68d5 100644
> > > --- a/fs/xfs/libxfs/xfs_attr_remote.h
> > > +++ b/fs/xfs/libxfs/xfs_attr_remote.h
> > > @@ -10,9 +10,12 @@ int xfs_attr3_rmt_blocks(struct xfs_mount *mp, int attrlen);
> > >   int xfs_attr_rmtval_get(struct xfs_da_args *args);
> > >   int xfs_attr_rmtval_set(struct xfs_da_args *args);
> > > -int xfs_attr_rmtval_remove(struct xfs_da_args *args);
> > >   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 3c1c830..96f93a7 100644
> > > --- a/fs/xfs/xfs_trace.h
> > > +++ b/fs/xfs/xfs_trace.h
> > > @@ -1943,7 +1943,6 @@ 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
> > >