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From: Chandan Babu R <chandanrlinux@gmail.com>
To: Allison Henderson <allison.henderson@oracle.com>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH v13 03/10] xfs: Add delay ready attr set routines
Date: Tue, 27 Oct 2020 19:02:55 +0530	[thread overview]
Message-ID: <534604869.YD8572SIOA@garuda> (raw)
In-Reply-To: <20201023063435.7510-4-allison.henderson@oracle.com>

On Friday 23 October 2020 12:04:28 PM IST Allison Henderson wrote:
> This patch modifies the attr set routines to be delay ready. This means
> they no longer roll or commit transactions, but instead return -EAGAIN
> to have the calling routine roll and refresh the transaction.  In this
> series, xfs_attr_set_args has become xfs_attr_set_iter, which uses a
> state machine like switch to keep track of where it was when EAGAIN was
> returned. See xfs_attr.h for a more detailed diagram of the states.
> 
> Two new helper functions have been added: xfs_attr_rmtval_set_init and
> xfs_attr_rmtval_set_blk.  They provide a subset of logic similar to
> xfs_attr_rmtval_set, but they store the current block in the delay attr
> context to allow the caller to roll the transaction between allocations.
> This helps to simplify and consolidate code used by
> xfs_attr_leaf_addname and xfs_attr_node_addname. xfs_attr_set_args has
> now become a simple loop to refresh the transaction until the operation
> is completed.  Lastly, xfs_attr_rmtval_remove is no longer used, and is
> removed.

One nit. xfs_attr_rmtval_remove()'s prototype declaration needs to be removed
from xfs_attr_remote.h.

> 
> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> ---
>  fs/xfs/libxfs/xfs_attr.c        | 370 ++++++++++++++++++++++++++--------------
>  fs/xfs/libxfs/xfs_attr.h        | 126 +++++++++++++-
>  fs/xfs/libxfs/xfs_attr_remote.c |  99 +++++++----
>  fs/xfs/libxfs/xfs_attr_remote.h |   4 +
>  fs/xfs/xfs_trace.h              |   1 -
>  5 files changed, 439 insertions(+), 161 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index 6ca94cb..95c98d7 100644
> --- a/fs/xfs/libxfs/xfs_attr.c
> +++ b/fs/xfs/libxfs/xfs_attr.c
> @@ -44,7 +44,7 @@ STATIC int xfs_attr_shortform_addname(xfs_da_args_t *args);
>   * Internal routines when attribute list is one block.
>   */
>  STATIC int xfs_attr_leaf_get(xfs_da_args_t *args);
> -STATIC int xfs_attr_leaf_addname(xfs_da_args_t *args);
> +STATIC int xfs_attr_leaf_addname(struct xfs_delattr_context *dac);
>  STATIC int xfs_attr_leaf_removename(xfs_da_args_t *args);
>  STATIC int xfs_attr_leaf_hasname(struct xfs_da_args *args, struct xfs_buf **bp);
>  
> @@ -52,12 +52,15 @@ STATIC int xfs_attr_leaf_hasname(struct xfs_da_args *args, struct xfs_buf **bp);
>   * Internal routines when attribute list is more than one block.
>   */
>  STATIC int xfs_attr_node_get(xfs_da_args_t *args);
> -STATIC int xfs_attr_node_addname(xfs_da_args_t *args);
> +STATIC int xfs_attr_node_addname(struct xfs_delattr_context *dac);
>  STATIC int xfs_attr_node_removename_iter(struct xfs_delattr_context *dac);
>  STATIC int xfs_attr_node_hasname(xfs_da_args_t *args,
>  				 struct xfs_da_state **state);
>  STATIC int xfs_attr_fillstate(xfs_da_state_t *state);
>  STATIC int xfs_attr_refillstate(xfs_da_state_t *state);
> +STATIC int xfs_attr_leaf_try_add(struct xfs_da_args *args, struct xfs_buf *bp);
> +STATIC int xfs_attr_set_iter(struct xfs_delattr_context *dac,
> +			     struct xfs_buf **leaf_bp);
>  
>  int
>  xfs_inode_hasattr(
> @@ -218,8 +221,11 @@ xfs_attr_is_shortform(
>  
>  /*
>   * Attempts to set an attr in shortform, or converts short form to leaf form if
> - * there is not enough room.  If the attr is set, the transaction is committed
> - * and set to NULL.
> + * there is not enough room.  This function is meant to operate as a helper
> + * routine to the delayed attribute functions.  It returns -EAGAIN to indicate
> + * that the calling function should roll the transaction, and then proceed to
> + * add the attr in leaf form.  This subroutine does not expect to be recalled
> + * again like the other delayed attr routines do.
>   */
>  STATIC int
>  xfs_attr_set_shortform(
> @@ -227,16 +233,16 @@ xfs_attr_set_shortform(
>  	struct xfs_buf		**leaf_bp)
>  {
>  	struct xfs_inode	*dp = args->dp;
> -	int			error, error2 = 0;
> +	int			error = 0;
>  
>  	/*
>  	 * Try to add the attr to the attribute list in the inode.
>  	 */
>  	error = xfs_attr_try_sf_addname(dp, args);
> +
> +	/* Should only be 0, -EEXIST or ENOSPC */
>  	if (error != -ENOSPC) {
> -		error2 = xfs_trans_commit(args->trans);
> -		args->trans = NULL;
> -		return error ? error : error2;
> +		return error;
>  	}
>  	/*
>  	 * It won't fit in the shortform, transform to a leaf block.  GROT:
> @@ -249,18 +255,10 @@ xfs_attr_set_shortform(
>  	/*
>  	 * Prevent the leaf buffer from being unlocked so that a concurrent AIL
>  	 * push cannot grab the half-baked leaf buffer and run into problems
> -	 * with the write verifier. Once we're done rolling the transaction we
> -	 * can release the hold and add the attr to the leaf.
> +	 * with the write verifier.
>  	 */
>  	xfs_trans_bhold(args->trans, *leaf_bp);
> -	error = xfs_defer_finish(&args->trans);
> -	xfs_trans_bhold_release(args->trans, *leaf_bp);
> -	if (error) {
> -		xfs_trans_brelse(args->trans, *leaf_bp);
> -		return error;
> -	}
> -
> -	return 0;
> +	return -EAGAIN;
>  }
>  
>  /*
> @@ -268,7 +266,7 @@ xfs_attr_set_shortform(
>   * also checks for a defer finish.  Transaction is finished and rolled as
>   * needed, and returns true of false if the delayed operation should continue.
>   */
> -int
> +STATIC int
>  xfs_attr_trans_roll(
>  	struct xfs_delattr_context	*dac)
>  {
> @@ -297,61 +295,130 @@ int
>  xfs_attr_set_args(
>  	struct xfs_da_args	*args)
>  {
> -	struct xfs_inode	*dp = args->dp;
> -	struct xfs_buf          *leaf_bp = NULL;
> -	int			error = 0;
> +	struct xfs_buf			*leaf_bp = NULL;
> +	int				error = 0;
> +	struct xfs_delattr_context	dac = {
> +		.da_args	= args,
> +	};
> +
> +	do {
> +		error = xfs_attr_set_iter(&dac, &leaf_bp);
> +		if (error != -EAGAIN)
> +			break;
> +
> +		error = xfs_attr_trans_roll(&dac);
> +		if (error)
> +			return error;
> +
> +		if (leaf_bp) {
> +			xfs_trans_bjoin(args->trans, leaf_bp);
> +			xfs_trans_bhold(args->trans, leaf_bp);
> +		}

When xfs_attr_set_iter() causes a "short form" attribute list to be converted
to "leaf form", leaf_bp would point to an xfs_buf which has been added to the
transaction and also XFS_BLI_HOLD flag is set on the buffer (last statement in
xfs_attr_set_shortform()). XFS_BLI_HOLD flag makes sure that the new
transaction allocated by xfs_attr_trans_roll() would continue to have leaf_bp
in the transaction's item list. Hence I think the above calls to
xfs_trans_bjoin() and xfs_trans_bhold() are not required. Please let me know
if I am missing something obvious here.


-- 
chandan




  reply	other threads:[~2020-10-27 13:33 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-23  6:34 [PATCH v13 00/10] xfs: Delayed Attributes Allison Henderson
2020-10-23  6:34 ` [PATCH v13 01/10] xfs: Add helper xfs_attr_node_remove_step Allison Henderson
2020-10-27  7:03   ` Chandan Babu R
2020-10-27 22:23     ` Allison Henderson
2020-10-27 12:15   ` Brian Foster
2020-10-27 15:33     ` Allison Henderson
2020-11-10 23:12   ` Darrick J. Wong
2020-11-13  1:38     ` Allison Henderson
2020-10-23  6:34 ` [PATCH v13 02/10] xfs: Add delay ready attr remove routines Allison Henderson
2020-10-27  9:59   ` Chandan Babu R
2020-10-27 15:32     ` Allison Henderson
2020-10-28 12:04       ` Chandan Babu R
2020-10-29  1:29         ` Allison Henderson
2020-11-14  0:53           ` Darrick J. Wong
2020-10-27 12:16   ` Brian Foster
2020-10-27 22:27     ` Allison Henderson
2020-10-28 12:28       ` Brian Foster
2020-10-29  1:03         ` Allison Henderson
2020-11-10 23:15     ` Darrick J. Wong
2020-11-10 23:43   ` Darrick J. Wong
2020-11-11  0:28     ` Dave Chinner
2020-11-13  4:00       ` Allison Henderson
2020-11-13  3:43     ` Allison Henderson
2020-11-14  1:18       ` Darrick J. Wong
2020-11-16  5:12         ` Allison Henderson
2020-10-23  6:34 ` [PATCH v13 03/10] xfs: Add delay ready attr set routines Allison Henderson
2020-10-27 13:32   ` Chandan Babu R [this message]
2020-11-10 21:57     ` Darrick J. Wong
2020-11-13  1:33       ` Allison Henderson
2020-11-13  9:16         ` Chandan Babu R
2020-11-13 17:12           ` Allison Henderson
2020-11-14  1:20             ` Darrick J. Wong
2020-11-10 23:10   ` Darrick J. Wong
2020-11-13  1:38     ` Allison Henderson
2020-11-14  1:35       ` Darrick J. Wong
2020-11-16  5:25         ` Allison Henderson
2020-10-23  6:34 ` [PATCH v13 04/10] xfs: Rename __xfs_attr_rmtval_remove Allison Henderson
2020-10-23  6:34 ` [PATCH v13 05/10] xfs: Set up infastructure for deferred attribute operations Allison Henderson
2020-11-10 21:51   ` Darrick J. Wong
2020-11-11  3:44     ` Darrick J. Wong
2020-11-13 17:06       ` Allison Henderson
2020-11-13  1:32     ` Allison Henderson
2020-11-14  2:00       ` Darrick J. Wong
2020-11-16  7:41         ` Allison Henderson
2020-10-23  6:34 ` [PATCH v13 06/10] xfs: Add xfs_attr_set_deferred and xfs_attr_remove_deferred Allison Henderson
2020-11-10 20:15   ` Darrick J. Wong
2020-11-13  1:27     ` Allison Henderson
2020-11-14  2:03       ` Darrick J. Wong
2020-10-23  6:34 ` [PATCH v13 07/10] xfs: Add feature bit XFS_SB_FEAT_INCOMPAT_LOG_DELATTR Allison Henderson
2020-11-10 20:10   ` Darrick J. Wong
2020-11-13  1:27     ` Allison Henderson
2020-11-19  2:36   ` Darrick J. Wong
2020-11-19  4:01     ` Allison Henderson
2020-10-23  6:34 ` [PATCH v13 08/10] xfs: Enable delayed attributes Allison Henderson
2020-10-23  6:34 ` [PATCH v13 09/10] xfs: Remove unused xfs_attr_*_args Allison Henderson
2020-11-10 20:07   ` Darrick J. Wong
2020-11-13  1:27     ` Allison Henderson
2020-10-23  6:34 ` [PATCH v13 10/10] xfs: Add delayed attributes error tag Allison Henderson

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