[PATCH v4 17/17] xfs: Add delay ready attr set routines

Allison Collins
2019-11-07T01:29:01Z

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_later, which uses a state machine to keep track
of where it was when EAGAIN was returned. Part of
xfs_attr_leaf_addname has been factored out into a new helper
function xfs_attr_leaf_try_add to allow transaction cycling between
the two routines, and the flipflags logic has been removed since we
can simply cancel the transaction upon error. xfs_attr_set_args
consists of a simple loop to refresh the transaction until the
operation is completed.

Signed-off-by: Allison Collins <allison.henderson@oracle.com>
---
fs/xfs/libxfs/xfs_attr.c | 435 +++++++++++++++++++++++------------------------
fs/xfs/libxfs/xfs_attr.h | 1 +
2 files changed, 211 insertions(+), 225 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index 38d5c5c..97e5ae0 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -58,6 +58,7 @@ 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
@@ -250,9 +251,79 @@ int
xfs_attr_set_args(
struct xfs_da_args *args)
{
+ int error = 0;
+ int err2 = 0;
+ struct xfs_buf *leaf_bp = NULL;
+
+ do {
+ error = xfs_attr_set_later(args, &leaf_bp);
+ if (error && error != -EAGAIN)
+ goto out;
+
+ xfs_trans_log_inode(args->trans, args->dp,
+ XFS_ILOG_CORE | XFS_ILOG_ADATA);
+
+ err2 = xfs_trans_roll(&args->trans);
+ if (err2) {
+ error = err2;
+ goto out;
+ }
+
+ /* Rejoin inode and leaf if needed */
+ xfs_trans_ijoin(args->trans, args->dp, 0);
+ if (leaf_bp) {
+ xfs_trans_bjoin(args->trans, leaf_bp);
+ xfs_trans_bhold(args->trans, leaf_bp);
+ }
+
+ } while (error == -EAGAIN);
+
+out:
+ 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.
+ */
+int
+xfs_attr_set_later(
+ struct xfs_da_args *args,
+ struct xfs_buf **leaf_bp)
+{
struct xfs_inode *dp = args->dp;
- struct xfs_buf *leaf_bp = NULL;
- int error, error2 = 0;;
+ int error = 0;
+ int sf_size;
+
+ /* State machine switch */
+ switch (args->dc.dc_state) {
+ case XFS_DC_SF_TO_LEAF:
+ goto sf_to_leaf;
+ case XFS_DC_ALLOC_LEAF:
+ case XFS_DC_FOUND_LBLK:
+ goto leaf;
+ case XFS_DC_FOUND_NBLK:
+ case XFS_DC_ALLOC_NODE:
+ case XFS_DC_LEAF_TO_NODE:
+ goto node;
+ default:
+ break;
+ }
+
+ /*
+ * New inodes may not have an attribute fork yet. So set the attribute
+ * fork appropriately
+ */
+ if (XFS_IFORK_Q((args->dp)) == 0) {
+ sf_size = sizeof(struct xfs_attr_sf_hdr) +
+ XFS_ATTR_SF_ENTSIZE_BYNAME(args->name.len, args->valuelen);
+ xfs_bmap_set_attrforkoff(args->dp, sf_size, NULL);
+ args->dp->i_afp = kmem_zone_zalloc(xfs_ifork_zone, 0);
+ args->dp->i_afp->if_flags = XFS_IFEXTENTS;
+ }

/*
* If the attribute list is non-existent or a shortform list,
@@ -272,21 +343,14 @@ xfs_attr_set_args(
* Try to add the attr to the attribute list in the inode.
*/
error = xfs_attr_try_sf_addname(dp, args);
- if (error != -ENOSPC) {
- if (dp->i_mount->m_flags & XFS_MOUNT_WSYNC)
- xfs_trans_set_sync(args->trans);
-
- error2 = xfs_trans_commit(args->trans);
- args->trans = NULL;
- return error ? error : error2;
- }
-
+ 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;

@@ -294,43 +358,42 @@ xfs_attr_set_args(
* 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;
- }
+
+ xfs_trans_bhold(args->trans, *leaf_bp);
+ args->dc.dc_state = XFS_DC_SF_TO_LEAF;
+ return -EAGAIN;
+ }
+sf_to_leaf:
+
+ /*
+ * After a shortform to leaf conversion, we need to hold the leaf and
+ * cylce out the transaction. When we get back, we need to release
+ * the leaf.
+ */
+ if (*leaf_bp != NULL) {
+ xfs_trans_brelse(args->trans, *leaf_bp);
+ *leaf_bp = NULL;
}

if (xfs_bmap_one_block(dp, XFS_ATTR_FORK)) {
+ error = xfs_attr_leaf_try_add(args, *leaf_bp);
+ if (error == -ENOSPC)
+ args->dc.dc_state = XFS_DC_LEAF_TO_NODE;
+ else if (error)
+ return error;
+ else
+ args->dc.dc_state = XFS_DC_FOUND_LBLK;
+ return -EAGAIN;
+leaf:
error = xfs_attr_leaf_addname(args);
if (error == -ENOSPC) {
- /*
- * Commit that transaction so that the node_addname()
- * call can manage its own transactions.
- */
- 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;
-
- /*
- * Fob the rest of the problem off on the Btree code.
- */
- error = xfs_attr_node_addname(args);
+ args->dc.dc_state = XFS_DC_LEAF_TO_NODE;
+ return -EAGAIN;
}
} else {
+ args->dc.dc_state = XFS_DC_LEAF_TO_NODE;
+node:
error = xfs_attr_node_addname(args);
}
return error;
@@ -764,27 +827,26 @@ 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)
{
- int error, forkoff;
- struct xfs_buf *bp = NULL;
+ int error, nmap;
struct xfs_inode *dp = args->dp;
+ struct xfs_bmbt_irec *map = &args->dc.map;

- 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;
+ /* State machine switch */
+ switch (args->dc.dc_state) {
+ case XFS_DC_ALLOC_LEAF:
+ goto alloc_leaf;
+ default:
+ break;
+ }

/*
* If there was an out-of-line value, allocate the blocks we
@@ -793,90 +855,58 @@ xfs_attr_leaf_addname(struct xfs_da_args *args)
* 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 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.
- */
- if (args->op_flags & XFS_DA_OP_RENAME) {
- /*
- * 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;
+ /* Open coded xfs_attr_rmtval_set without trans handling */

- /*
- * Dismantle the "old" attribute/value pair by removing
- * a "remote" value (if it exists).
- */
- args->index = args->index2;
- args->blkno = args->blkno2;
- args->rmtblkno = args->rmtblkno2;
- args->rmtblkcnt = args->rmtblkcnt2;
- args->rmtvaluelen = args->rmtvaluelen2;
- if (args->rmtblkno) {
- error = xfs_attr_rmtval_remove(args);
- if (error)
- return error;
- }
+ args->dc.lfileoff = 0;
+ args->dc.lblkno = 0;
+ args->dc.blkcnt = 0;
+ args->rmtblkcnt = 0;
+ args->rmtblkno = 0;
+ memset(map, 0, sizeof(struct xfs_bmbt_irec));

- /*
- * 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,
- XFS_DABUF_MAP_NOMAPPING, &bp);
+ error = xfs_attr_rmt_find_hole(args);
if (error)
return error;

- xfs_attr3_leaf_remove(bp, args);
+ args->dc.blkcnt = args->rmtblkcnt;
+ args->dc.lblkno = args->rmtblkno;

/*
- * If the result is small enough, shrink it all into the inode.
+ * Roll through the "value", allocating blocks on disk as
+ * required.
*/
- if ((forkoff = xfs_attr_shortform_allfit(bp, dp))) {
- error = xfs_attr3_leaf_to_shortform(bp, args, forkoff);
- /* bp is gone due to xfs_da_shrink_inode */
- if (error)
- return error;
- error = xfs_defer_finish(&args->trans);
+alloc_leaf:
+ while (args->dc.blkcnt > 0) {
+ nmap = 1;
+ error = xfs_bmapi_write(args->trans, dp,
+ (xfs_fileoff_t)args->dc.lblkno,
+ args->dc.blkcnt, XFS_BMAPI_ATTRFORK,
+ args->total, map, &nmap);
if (error)
return error;
- }
+ ASSERT(nmap == 1);
+ ASSERT((map->br_startblock != DELAYSTARTBLOCK) &&
+ (map->br_startblock != HOLESTARTBLOCK));

- /*
- * Commit the remove and start the next trans in series.
- */
- error = xfs_trans_roll_inode(&args->trans, dp);
+ /* roll attribute extent map forwards */
+ args->dc.lblkno += map->br_blockcount;
+ args->dc.blkcnt -= map->br_blockcount;

- } else if (args->rmtblkno > 0) {
- /*
- * Added a "remote" value, just clear the incomplete flag.
- */
- error = xfs_attr3_leaf_clearflag(args);
+ args->dc.dc_state = XFS_DC_ALLOC_LEAF;
+ return -EAGAIN;
+ }
+
+ error = xfs_attr_rmtval_set_value(args);
if (error)
return error;
+ }

+ if (args->rmtblkno > 0) {
/*
- * Commit the flag value change and start the next trans in
- * series.
+ * Added a "remote" value, just clear the incomplete flag.
*/
- error = xfs_trans_roll_inode(&args->trans, args->dp);
+ error = xfs_attr3_leaf_clearflag(args);
}
return error;
}
@@ -1017,16 +1047,23 @@ 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_da_state *state;
+ struct xfs_da_state *state = NULL;
struct xfs_da_state_blk *blk;
struct xfs_inode *dp;
- struct xfs_mount *mp;
- int retval, error;
+ int retval = 0;
+ int error = 0;
+ int nmap;
+ struct xfs_bmbt_irec *map = &args->dc.map;

trace_xfs_attr_node_addname(args);

@@ -1034,8 +1071,17 @@ xfs_attr_node_addname(
* Fill in bucket of arguments/results/context to carry around.
*/
dp = args->dp;
- mp = dp->i_mount;
-restart:
+
+ /* State machine switch */
+ switch (args->dc.dc_state) {
+ case XFS_DC_FOUND_NBLK:
+ goto found_nblk;
+ case XFS_DC_ALLOC_NODE:
+ goto alloc_node;
+ default:
+ break;
+ }
+
/*
* Search to see if name already exists, and get back a pointer
* to where it should go.
@@ -1085,19 +1131,12 @@ xfs_attr_node_addname(
error = xfs_attr3_leaf_to_node(args);
if (error)
goto out;
- error = xfs_defer_finish(&args->trans);
- if (error)
- goto out;

/*
- * Commit the node conversion and start the next
- * trans in the chain.
+ * Restart routine from the top. No need to set the
+ * state
*/
- error = xfs_trans_roll_inode(&args->trans, dp);
- if (error)
- goto out;
-
- goto restart;
+ return -EAGAIN;
}

/*
@@ -1109,9 +1148,6 @@ xfs_attr_node_addname(
error = xfs_da3_split(state);
if (error)
goto out;
- error = xfs_defer_finish(&args->trans);
- if (error)
- goto out;
} else {
/*
* Addition succeeded, update Btree hashvals.
@@ -1126,13 +1162,9 @@ 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;
+ args->dc.dc_state = XFS_DC_FOUND_NBLK;
+ return -EAGAIN;
+found_nblk:

/*
* If there was an out-of-line value, allocate the blocks we
@@ -1141,104 +1173,57 @@ xfs_attr_node_addname(
* maximum size of a transaction and/or hit a deadlock.
*/
if (args->rmtblkno > 0) {
- error = xfs_attr_rmtval_set(args);
- if (error)
- return error;
- }
+ /* Open coded xfs_attr_rmtval_set without trans handling */
+ args->dc.lblkno = 0;
+ args->dc.lfileoff = 0;
+ args->dc.blkcnt = 0;
+ args->rmtblkcnt = 0;
+ args->rmtblkno = 0;
+ memset(map, 0, sizeof(struct xfs_bmbt_irec));

- /*
- * 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.
- */
- if (args->op_flags & XFS_DA_OP_RENAME) {
- /*
- * 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);
+ error = xfs_attr_rmt_find_hole(args);
if (error)
- goto out;
+ return error;

+ args->dc.blkcnt = args->rmtblkcnt;
+ args->dc.lblkno = args->rmtblkno;
/*
- * Dismantle the "old" attribute/value pair by removing
- * a "remote" value (if it exists).
+ * Roll through the "value", allocating blocks on disk as
+ * required.
*/
- args->index = args->index2;
- args->blkno = args->blkno2;
- args->rmtblkno = args->rmtblkno2;
- args->rmtblkcnt = args->rmtblkcnt2;
- args->rmtvaluelen = args->rmtvaluelen2;
- if (args->rmtblkno) {
- error = xfs_attr_rmtval_remove(args);
+alloc_node:
+ while (args->dc.blkcnt > 0) {
+ nmap = 1;
+ error = xfs_bmapi_write(args->trans, dp,
+ (xfs_fileoff_t)args->dc.lblkno, args->dc.blkcnt,
+ XFS_BMAPI_ATTRFORK, args->total, map, &nmap);
if (error)
return error;
- }

- /*
- * 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.
- */
- args->name.type |= XFS_ATTR_INCOMPLETE;
- state = xfs_da_state_alloc();
- state->args = args;
- state->mp = mp;
- state->inleaf = 0;
- error = xfs_da3_node_lookup_int(state, &retval);
- if (error)
- goto out;
+ ASSERT(nmap == 1);
+ ASSERT((map->br_startblock != DELAYSTARTBLOCK) &&
+ (map->br_startblock != HOLESTARTBLOCK));

- /*
- * 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);
- error = xfs_attr3_leaf_remove(blk->bp, args);
- xfs_da3_fixhashpath(state, &state->path);
+ /* roll attribute extent map forwards */
+ args->dc.lblkno += map->br_blockcount;
+ args->dc.blkcnt -= map->br_blockcount;

- /*
- * 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;
+ args->dc.dc_state = XFS_DC_ALLOC_NODE;
+ return -EAGAIN;
}

- /*
- * Commit and start the next trans in the chain.
- */
- error = xfs_trans_roll_inode(&args->trans, dp);
+ error = xfs_attr_rmtval_set_value(args);
if (error)
- goto out;
+ return error;
+ }

- } else if (args->rmtblkno > 0) {
+ if (args->rmtblkno > 0) {
/*
* Added a "remote" value, just clear the incomplete flag.
*/
error = xfs_attr3_leaf_clearflag(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;
}
retval = error = 0;

diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
index fb8bf5b..c710387 100644
--- a/fs/xfs/libxfs/xfs_attr.h
+++ b/fs/xfs/libxfs/xfs_attr.h
@@ -149,6 +149,7 @@ int xfs_attr_get(struct xfs_inode *ip, struct xfs_name *name,
int xfs_attr_set(struct xfs_inode *dp, struct xfs_name *name,
unsigned char *value, int valuelen, int flags);
int xfs_attr_set_args(struct xfs_da_args *args);
+int xfs_attr_set_later(struct xfs_da_args *args, struct xfs_buf **leaf_bp);
int xfs_attr_remove(struct xfs_inode *dp, struct xfs_name *name, int flags);
int xfs_has_attr(struct xfs_da_args *args);
int xfs_attr_remove_args(struct xfs_da_args *args);
--
2.7.4