On Fri, 18 Dec 2020 00:29:07 -0700, Allison Henderson wrote:
> This patch modifies the attr set routines to be delay ready. This means
> they no longer roll or commit transactions, but instead return -EAGAIN
> to have the calling routine roll and refresh the transaction. In this
> series, xfs_attr_set_args has become xfs_attr_set_iter, which uses a
> state machine like switch to keep track of where it was when EAGAIN was
> returned. See xfs_attr.h for a more detailed diagram of the states.
>
> Two new helper functions have been added: xfs_attr_rmtval_set_init and
I don't see xfs_attr_rmtval_set_init() being added in this patch. Maybe it
needs to be removed from the description.
> 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@xxxxxxxxxx>
> ---
> fs/xfs/libxfs/xfs_attr.c | 357 ++++++++++++++++++++++++++--------------
> fs/xfs/libxfs/xfs_attr.h | 235 +++++++++++++++++++++++++-
> fs/xfs/libxfs/xfs_attr_remote.c | 98 +++++++----
> fs/xfs/libxfs/xfs_attr_remote.h | 5 +-
> fs/xfs/xfs_trace.h | 1 -
> 5 files changed, 541 insertions(+), 155 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> index b6330f9..cd72512 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 +255,15 @@ 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;
> + /*
> + * 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.
> + */
> + return -EAGAIN;
> }
>
> /*
> @@ -268,7 +271,7 @@ 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)
> {
> @@ -298,34 +301,95 @@ 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;
> + } while (true);
> +
> + return error;
> +}
> +
> +/*
> + * Set the attribute specified in @args.
> + * This routine is meant to function as a delayed operation, and may return
> + * -EAGAIN when the transaction needs to be rolled. Calling functions will need
> + * to handle this, and recall the function until a successful error code is
> + * returned.
> + */
> +STATIC int
> +xfs_attr_set_iter(
> + struct xfs_delattr_context *dac,
> + struct xfs_buf **leaf_bp)
> +{
> + struct xfs_da_args *args = dac->da_args;
> + struct xfs_inode *dp = args->dp;
> + int error = 0;
> +
> + /* State machine switch */
> + switch (dac->dela_state) {
> + case XFS_DAS_FLIP_LFLAG:
> + case XFS_DAS_FOUND_LBLK:
> + case XFS_DAS_RM_LBLK:
> + return xfs_attr_leaf_addname(dac);
> + case XFS_DAS_FOUND_NBLK:
> + case XFS_DAS_FLIP_NFLAG:
> + case XFS_DAS_ALLOC_NODE:
> + return xfs_attr_node_addname(dac);
> + case XFS_DAS_UNINIT:
> + break;
> + default:
> + ASSERT(dac->dela_state != XFS_DAS_RM_SHRINK);
> + break;
> + }
>
> /*
> * If the attribute list is already in leaf format, jump straight to
> * leaf handling. Otherwise, try to add the attribute to the shortform
> * list; if there's no room then convert the list to leaf format and try
> - * again.
> + * again. No need to set state as we will be in leaf form when we come
> + * back
> */
> if (xfs_attr_is_shortform(dp)) {
>
> /*
> - * If the attr was successfully set in shortform, the
> - * transaction is committed and set to NULL. Otherwise, is it
> - * converted from shortform to leaf, and the transaction is
> - * retained.
> + * If the attr was successfully set in shortform, no need to
> + * continue. Otherwise, is it converted from shortform to leaf
> + * and -EAGAIN is returned.
> */
> - error = xfs_attr_set_shortform(args, &leaf_bp);
> - if (error || !args->trans)
> - return error;
> + error = xfs_attr_set_shortform(args, leaf_bp);
> + if (error == -EAGAIN)
> + dac->flags |= XFS_DAC_DEFER_FINISH;
> +
> + return error;
> }
>
> - if (xfs_bmap_one_block(dp, XFS_ATTR_FORK)) {
> - error = xfs_attr_leaf_addname(args);
> - if (error != -ENOSPC)
> - return error;
> + /*
> + * After a shortform to leaf conversion, we need to hold the leaf and
> + * cycle out the transaction. When we get back, we need to release
> + * the leaf to release the hold on the leaf buffer.
> + */
> + if (*leaf_bp != NULL) {
> + xfs_trans_bhold_release(args->trans, *leaf_bp);
> + *leaf_bp = NULL;
> + }
> +
> + if (!xfs_bmap_one_block(dp, XFS_ATTR_FORK))
> + return xfs_attr_node_addname(dac);
>
> + error = xfs_attr_leaf_try_add(args, *leaf_bp);
> + switch (error) {
> + case -ENOSPC:
> /*
> * Promote the attribute list to the Btree format.
> */
> @@ -334,25 +398,22 @@ xfs_attr_set_args(
> 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.
> + * 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
... node handling code above?.
Apart from the above nits I don't see any issues w.r.t the logical correctness
of the code. Hence,
Reviewed-by: Chandan Babu R <chandanrlinux@xxxxxxxxx>
> */
> - error = xfs_trans_roll_inode(&args->trans, dp);
> - if (error)
> - return error;
> + dac->flags |= XFS_DAC_DEFER_FINISH;
> + return -EAGAIN;
> + case 0:
> + dac->dela_state = XFS_DAS_FOUND_LBLK;
> + return -EAGAIN;
> }
> -
> - error = xfs_attr_node_addname(args);
> return error;
> }
>
> @@ -728,28 +789,30 @@ xfs_attr_leaf_try_add(
> *
> * This leaf block cannot have a "remote" value, we only call this routine
> * if bmap_one_block() says there is only one block (ie: no remote blks).
> + *
> + * This routine is meant to function as a delayed operation, and may return
> + * -EAGAIN when the transaction needs to be rolled. Calling functions will need
> + * to handle this, and recall the function until a successful error code is
> + * returned.
> */
> STATIC int
> xfs_attr_leaf_addname(
> - struct xfs_da_args *args)
> + struct xfs_delattr_context *dac)
> {
> - int error, forkoff;
> - struct xfs_buf *bp = NULL;
> - struct xfs_inode *dp = args->dp;
> -
> - trace_xfs_attr_leaf_addname(args);
> -
> - error = xfs_attr_leaf_try_add(args, bp);
> - if (error)
> - return error;
> + struct xfs_da_args *args = dac->da_args;
> + struct xfs_buf *bp = NULL;
> + int error, forkoff;
> + struct xfs_inode *dp = args->dp;
>
> - /*
> - * Commit the transaction that added the attr name so that
> - * later routines can manage their own transactions.
> - */
> - error = xfs_trans_roll_inode(&args->trans, dp);
> - if (error)
> - return error;
> + /* State machine switch */
> + switch (dac->dela_state) {
> + case XFS_DAS_FLIP_LFLAG:
> + goto das_flip_flag;
> + case XFS_DAS_RM_LBLK:
> + goto das_rm_lblk;
> + default:
> + break;
> + }
>
> /*
> * If there was an out-of-line value, allocate the blocks we
> @@ -757,12 +820,34 @@ xfs_attr_leaf_addname(
> * after we create the attribute so that we don't overflow the
> * maximum size of a transaction and/or hit a deadlock.
> */
> - if (args->rmtblkno > 0) {
> - error = xfs_attr_rmtval_set(args);
> +
> + /* Open coded xfs_attr_rmtval_set without trans handling */
> + if ((dac->flags & XFS_DAC_LEAF_ADDNAME_INIT) == 0) {
> + dac->flags |= XFS_DAC_LEAF_ADDNAME_INIT;
> + if (args->rmtblkno > 0) {
> + error = xfs_attr_rmtval_find_space(dac);
> + if (error)
> + return error;
> + }
> + }
> +
> + /*
> + * Roll through the "value", allocating blocks on disk as
> + * required.
> + */
> + if (dac->blkcnt > 0) {
> + error = xfs_attr_rmtval_set_blk(dac);
> if (error)
> return error;
> +
> + dac->flags |= XFS_DAC_DEFER_FINISH;
> + return -EAGAIN;
> }
>
> + error = xfs_attr_rmtval_set_value(args);
> + if (error)
> + return error;
> +
> if (!(args->op_flags & XFS_DA_OP_RENAME)) {
> /*
> * Added a "remote" value, just clear the incomplete flag.
> @@ -782,29 +867,30 @@ xfs_attr_leaf_addname(
> * In a separate transaction, set the incomplete flag on the "old" attr
> * and clear the incomplete flag on the "new" attr.
> */
> -
> error = xfs_attr3_leaf_flipflags(args);
> if (error)
> return error;
> /*
> * Commit the flag value change and start the next trans in series.
> */
> - error = xfs_trans_roll_inode(&args->trans, args->dp);
> - if (error)
> - return error;
> -
> + dac->dela_state = XFS_DAS_FLIP_LFLAG;
> + return -EAGAIN;
> +das_flip_flag:
> /*
> * Dismantle the "old" attribute/value pair by removing a "remote" value
> * (if it exists).
> */
> xfs_attr_restore_rmt_blk(args);
>
> - if (args->rmtblkno) {
> - error = xfs_attr_rmtval_invalidate(args);
> - if (error)
> - return error;
> + error = xfs_attr_rmtval_invalidate(args);
> + if (error)
> + return error;
>
> - error = xfs_attr_rmtval_remove(args);
> + /* Set state in case xfs_attr_rmtval_remove returns -EAGAIN */
> + dac->dela_state = XFS_DAS_RM_LBLK;
> +das_rm_lblk:
> + if (args->rmtblkno) {
> + error = __xfs_attr_rmtval_remove(dac);
> if (error)
> return error;
> }
> @@ -970,23 +1056,38 @@ xfs_attr_node_hasname(
> *
> * "Remote" attribute values confuse the issue and atomic rename operations
> * add a whole extra layer of confusion on top of that.
> + *
> + * This routine is meant to function as a delayed operation, and may return
> + * -EAGAIN when the transaction needs to be rolled. Calling functions will need
> + * to handle this, and recall the function until a successful error code is
> + *returned.
> */
> STATIC int
> xfs_attr_node_addname(
> - struct xfs_da_args *args)
> + struct xfs_delattr_context *dac)
> {
> - struct xfs_da_state *state;
> - struct xfs_da_state_blk *blk;
> - struct xfs_inode *dp;
> - int retval, error;
> + struct xfs_da_args *args = dac->da_args;
> + struct xfs_da_state *state = NULL;
> + struct xfs_da_state_blk *blk;
> + int retval = 0;
> + int error = 0;
>
> trace_xfs_attr_node_addname(args);
>
> - /*
> - * Fill in bucket of arguments/results/context to carry around.
> - */
> - dp = args->dp;
> -restart:
> + /* State machine switch */
> + switch (dac->dela_state) {
> + case XFS_DAS_FLIP_NFLAG:
> + goto das_flip_flag;
> + case XFS_DAS_FOUND_NBLK:
> + goto das_found_nblk;
> + case XFS_DAS_ALLOC_NODE:
> + goto das_alloc_node;
> + case XFS_DAS_RM_NBLK:
> + goto das_rm_nblk;
> + default:
> + break;
> + }
> +
> /*
> * Search to see if name already exists, and get back a pointer
> * to where it should go.
> @@ -1032,19 +1133,16 @@ 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;
> -
> - goto restart;
> + dac->flags |= XFS_DAC_DEFER_FINISH;
> + return -EAGAIN;
> }
>
> /*
> @@ -1056,9 +1154,7 @@ 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.
> @@ -1066,6 +1162,11 @@ xfs_attr_node_addname(
> xfs_da3_fixhashpath(state, &state->path);
> }
>
> + if (!args->rmtblkno && !(args->op_flags & XFS_DA_OP_RENAME)) {
> + retval = error;
> + goto out;
> + }
> +
> /*
> * Kill the state structure, we're done with it and need to
> * allow the buffers to come back later.
> @@ -1073,13 +1174,9 @@ xfs_attr_node_addname(
> xfs_da_state_free(state);
> state = NULL;
>
> - /*
> - * Commit the leaf addition or btree split and start the next
> - * trans in the chain.
> - */
> - error = xfs_trans_roll_inode(&args->trans, dp);
> - if (error)
> - goto out;
> + dac->dela_state = XFS_DAS_FOUND_NBLK;
> + return -EAGAIN;
> +das_found_nblk:
>
> /*
> * If there was an out-of-line value, allocate the blocks we
> @@ -1088,7 +1185,27 @@ xfs_attr_node_addname(
> * maximum size of a transaction and/or hit a deadlock.
> */
> if (args->rmtblkno > 0) {
> - error = xfs_attr_rmtval_set(args);
> + /* Open coded xfs_attr_rmtval_set without trans handling */
> + error = xfs_attr_rmtval_find_space(dac);
> + if (error)
> + return error;
> +
> + /*
> + * Roll through the "value", allocating blocks on disk as
> + * required. Set the state in case of -EAGAIN return code
> + */
> + dac->dela_state = XFS_DAS_ALLOC_NODE;
> +das_alloc_node:
> + if (dac->blkcnt > 0) {
> + error = xfs_attr_rmtval_set_blk(dac);
> + if (error)
> + return error;
> +
> + dac->flags |= XFS_DAC_DEFER_FINISH;
> + return -EAGAIN;
> + }
> +
> + error = xfs_attr_rmtval_set_value(args);
> if (error)
> return error;
> }
> @@ -1118,22 +1235,24 @@ xfs_attr_node_addname(
> /*
> * Commit the flag value change and start the next trans in series
> */
> - error = xfs_trans_roll_inode(&args->trans, args->dp);
> - if (error)
> - goto out;
> -
> + dac->dela_state = XFS_DAS_FLIP_NFLAG;
> + return -EAGAIN;
> +das_flip_flag:
> /*
> * Dismantle the "old" attribute/value pair by removing a "remote" value
> * (if it exists).
> */
> xfs_attr_restore_rmt_blk(args);
>
> - if (args->rmtblkno) {
> - error = xfs_attr_rmtval_invalidate(args);
> - if (error)
> - return error;
> + error = xfs_attr_rmtval_invalidate(args);
> + if (error)
> + return error;
>
> - error = xfs_attr_rmtval_remove(args);
> + /* Set state in case xfs_attr_rmtval_remove returns -EAGAIN */
> + dac->dela_state = XFS_DAS_RM_NBLK;
> +das_rm_nblk:
> + if (args->rmtblkno) {
> + error = __xfs_attr_rmtval_remove(dac);
> if (error)
> return error;
> }
> diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
> index 3154ef4..e101238 100644
> --- a/fs/xfs/libxfs/xfs_attr.h
> +++ b/fs/xfs/libxfs/xfs_attr.h
> @@ -135,6 +135,227 @@ struct xfs_attr_list_context {
> * v
> * done
> *
> + *
> + * Below is a state machine diagram for attr set operations.
> + *
> + * It seems the challenge with undertanding 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
> + * statemachine. 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 statemachine to
> + * a subroutine, it needs to respect the simple rule that it doesn't "own" the
> + * statemachine 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 statemachine.
> + *
> + * xfs_attr_set_iter()
> + * │
> + * v
> + * ┌─y─ has an attr fork?
> + * │ |
> + * │ n
> + * │ |
> + * │ V
> + * │ add a fork
> + * │ │
> + * └──────────┤
> + * │
> + * V
> + * ┌─n── is shortform?
> + * │ |
> + * │ y
> + * │ |
> + * │ V
> + * │ xfs_attr_set_shortform
> + * │ |
> + * │ V
> + * │ had enough ──y──> done
> + * │ space?
> + * │ │
> + * │ n
> + * │ │
> + * │ V
> + * │ return -EAGAIN
> + * │ Re-enter in leaf form
> + * │ │
> + * └──────────┤
> + * │
> + * V
> + * release leaf buffer
> + * if needed
> + * │
> + * V
> + * ┌───n── fork has
> + * │ only 1 blk?
> + * │ │
> + * │ y
> + * │ │
> + * │ v
> + * │ xfs_attr_leaf_try_add()
> + * │ │
> + * │ v
> + * │ had enough
> + * │ ┌────n── space?
> + * │ │ │
> + * │ v │
> + * │ return -EAGAIN │
> + * │ re-enter in y
> + * │ node form │
> + * │ │ │
> + * ├───────┘ │
> + * │ v
> + * │ XFS_DAS_FOUND_LBLK ──┐
> + * │ │
> + * │ XFS_DAS_FLIP_LFLAG ──┤
> + * │ (subroutine state) │
> + * │ │
> + * │ └─>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 │
> + * │ remove │
> + * │ XFS_DAS_RM_LBLK ─> old name │
> + * │ ^ │ │
> + * │ │ v │
> + * │ └──────y── more to │
> + * │ remove │
> + * │ │ │
> + * │ n │
> + * │ │ │
> + * │ v │
> + * │ done <──────┘
> + * └──> XFS_DAS_FOUND_NBLK ──┐
> + * (subroutine state) │
> + * │
> + * XFS_DAS_ALLOC_NODE ──┤
> + * (subroutine state) │
> + * │
> + * XFS_DAS_FLIP_NFLAG ──┤
> + * (subroutine state) │
> + * │
> + * └─>xfs_attr_node_addname()
> + * │
> + * v
> + * determine if this
> + * is create or rename
> + * find space to store attr
> + * │
> + * v
> + * ┌──────n──── fits in a node leaf?
> + * │ ^ │
> + * single leaf node? │ │
> + * │ │ │ y
> + * n y │ │
> + * │ │ │ v
> + * v v │ update
> + * split if grow the leaf ─┘ hashvals
> + * needed return -EAGAIN │
> + * │ retry leaf add │
> + * │ on reentry │
> + * │ │
> + * └───────────────────────────┤
> + * v
> + * need to alloc ──n──> done
> + * or flip flag?
> + * │
> + * y
> + * │
> + * v
> + * 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 │
> + * remove │
> + * XFS_DAS_RM_NBLK ─> old name │
> + * ^ │ │
> + * │ v │
> + * └──────y── more to │
> + * remove │
> + * │ │
> + * n │
> + * │ │
> + * v │
> + * done <──────┘
> + *
> */
>
> /*
> @@ -149,12 +370,20 @@ struct xfs_attr_list_context {
> enum xfs_delattr_state {
> XFS_DAS_UNINIT = 0, /* No state has been set yet */
> XFS_DAS_RM_SHRINK, /* We are shrinking the tree */
> + XFS_DAS_FOUND_LBLK, /* We found leaf blk for attr */
> + XFS_DAS_FOUND_NBLK, /* We found node blk for attr */
> + XFS_DAS_FLIP_LFLAG, /* Flipped leaf INCOMPLETE attr flag */
> + XFS_DAS_RM_LBLK, /* A rename is removing leaf blocks */
> + XFS_DAS_ALLOC_NODE, /* We are allocating node blocks */
> + XFS_DAS_FLIP_NFLAG, /* Flipped node INCOMPLETE attr flag */
> + XFS_DAS_RM_NBLK, /* A rename is removing node blocks */
> };
>
> /*
> * 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
> @@ -162,6 +391,11 @@ 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;
>
> @@ -188,7 +422,6 @@ 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 f09820c..6af86bf 100644
> --- a/fs/xfs/libxfs/xfs_attr_remote.c
> +++ b/fs/xfs/libxfs/xfs_attr_remote.c
> @@ -441,7 +441,7 @@ xfs_attr_rmtval_get(
> * Find a "hole" in the attribute address space large enough for us to drop the
> * new attribute's value into
> */
> -STATIC int
> +int
> xfs_attr_rmt_find_hole(
> struct xfs_da_args *args)
> {
> @@ -468,7 +468,7 @@ xfs_attr_rmt_find_hole(
> return 0;
> }
>
> -STATIC int
> +int
> xfs_attr_rmtval_set_value(
> struct xfs_da_args *args)
> {
> @@ -628,6 +628,69 @@ xfs_attr_rmtval_set(
> }
>
> /*
> + * Find a hole for the attr and store it in the delayed attr context. This
> + * initializes the context to roll through allocating an attr extent for a
> + * delayed attr operation
> + */
> +int
> +xfs_attr_rmtval_find_space(
> + struct xfs_delattr_context *dac)
> +{
> + struct xfs_da_args *args = dac->da_args;
> + struct xfs_bmbt_irec *map = &dac->map;
> + int error;
> +
> + dac->lblkno = 0;
> + dac->blkcnt = 0;
> + args->rmtblkcnt = 0;
> + args->rmtblkno = 0;
> + memset(map, 0, sizeof(struct xfs_bmbt_irec));
> +
> + error = xfs_attr_rmt_find_hole(args);
> + if (error)
> + return error;
> +
> + dac->blkcnt = args->rmtblkcnt;
> + dac->lblkno = args->rmtblkno;
> +
> + return 0;
> +}
> +
> +/*
> + * Write one block of the value associated with an attribute into the
> + * out-of-line buffer that we have defined for it. This is similar to a subset
> + * of xfs_attr_rmtval_set, but records the current block to the delayed attr
> + * context, and leaves transaction handling to the caller.
> + */
> +int
> +xfs_attr_rmtval_set_blk(
> + struct xfs_delattr_context *dac)
> +{
> + struct xfs_da_args *args = dac->da_args;
> + struct xfs_inode *dp = args->dp;
> + struct xfs_bmbt_irec *map = &dac->map;
> + int nmap;
> + int error;
> +
> + nmap = 1;
> + error = xfs_bmapi_write(args->trans, dp, (xfs_fileoff_t)dac->lblkno,
> + dac->blkcnt, XFS_BMAPI_ATTRFORK, args->total,
> + map, &nmap);
> + if (error)
> + return error;
> +
> + ASSERT(nmap == 1);
> + ASSERT((map->br_startblock != DELAYSTARTBLOCK) &&
> + (map->br_startblock != HOLESTARTBLOCK));
> +
> + /* roll attribute extent map forwards */
> + dac->lblkno += map->br_blockcount;
> + dac->blkcnt -= map->br_blockcount;
> +
> + return 0;
> +}
> +
> +/*
> * Remove the value associated with an attribute by deleting the
> * out-of-line buffer that it is stored on.
> */
> @@ -669,37 +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 != -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 5a263ae..9074b8b 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, \
>
--
chandan
