xfs: get rid of the log item descriptor

It's just a connector between a transaction and a log item. There's
a 1:1 relationship between a log item descriptor and a log item,
and a 1:1 relationship between a log item descriptor and a
transaction. Both relationships are created and terminated at the
same time, so why do we even have the descriptor?

Replace it with a specific list_head in the log item and a new
log item dirtied flag to replace the XFS_LID_DIRTY flag.

Signed-Off-By: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
[darrick: fix up deferred agfl intent finish_item use of LID_DIRTY]
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/libxfs/xfs_bmap.c

@@ -246,7 +246,7 @@ xfs_bmap_get_bp(
 	struct xfs_btree_cur	*cur,
 	xfs_fsblock_t		bno)
 {
-	struct xfs_log_item_desc *lidp;
+	struct xfs_log_item	*lip;
 	int			i;
 
 	if (!cur)
@@ -260,9 +260,9 @@ xfs_bmap_get_bp(
 	}
 
 	/* Chase down all the log items to see if the bp is there */
-	list_for_each_entry(lidp, &cur->bc_tp->t_items, lid_trans) {
-		struct xfs_buf_log_item	*bip;
-		bip = (struct xfs_buf_log_item *)lidp->lid_item;
+	list_for_each_entry(lip, &cur->bc_tp->t_items, li_trans) {
+		struct xfs_buf_log_item	*bip = (struct xfs_buf_log_item *)lip;
+
 		if (bip->bli_item.li_type == XFS_LI_BUF &&
 		    XFS_BUF_ADDR(bip->bli_buf) == bno)
 			return bip->bli_buf;

fs/xfs/libxfs/xfs_shared.h

@@ -57,21 +57,6 @@ extern const struct xfs_buf_ops xfs_sb_quiet_buf_ops;
 extern const struct xfs_buf_ops xfs_symlink_buf_ops;
 extern const struct xfs_buf_ops xfs_rtbuf_ops;
 
-/*
- * This structure is used to track log items associated with
- * a transaction.  It points to the log item and keeps some
- * flags to track the state of the log item.  It also tracks
- * the amount of space needed to log the item it describes
- * once we get to commit processing (see xfs_trans_commit()).
- */
-struct xfs_log_item_desc {
-	struct xfs_log_item	*lid_item;
-	struct list_head	lid_trans;
-	unsigned char		lid_flags;
-};
-
-#define XFS_LID_DIRTY		0x1
-
 /* log size calculation functions */
 int	xfs_log_calc_unit_res(struct xfs_mount *mp, int unit_bytes);
 int	xfs_log_calc_minimum_size(struct xfs_mount *);

fs/xfs/xfs_buf_item.c

@@ -438,7 +438,7 @@ xfs_buf_item_unpin(
 			 * xfs_trans_uncommit() will try to reference the
 			 * buffer which we no longer have a hold on.
 			 */
-			if (lip->li_desc)
+			if (!list_empty(&lip->li_trans))
 				xfs_trans_del_item(lip);
 
 			/*

fs/xfs/xfs_icreate_item.c

@@ -184,5 +184,5 @@ xfs_icreate_log(
 
 	xfs_trans_add_item(tp, &icp->ic_item);
 	tp->t_flags |= XFS_TRANS_DIRTY;
-	icp->ic_item.li_desc->lid_flags |= XFS_LID_DIRTY;
+	set_bit(XFS_LI_DIRTY, &icp->ic_item.li_flags);
 }

fs/xfs/xfs_log.c

@@ -1047,6 +1047,7 @@ xfs_log_item_init(
 	INIT_LIST_HEAD(&item->li_ail);
 	INIT_LIST_HEAD(&item->li_cil);
 	INIT_LIST_HEAD(&item->li_bio_list);
+	INIT_LIST_HEAD(&item->li_trans);
 }
 
 /*
@@ -2110,10 +2111,10 @@ xlog_print_tic_res(
  */
 void
 xlog_print_trans(
-	struct xfs_trans		*tp)
+	struct xfs_trans	*tp)
 {
-	struct xfs_mount		*mp = tp->t_mountp;
-	struct xfs_log_item_desc	*lidp;
+	struct xfs_mount	*mp = tp->t_mountp;
+	struct xfs_log_item	*lip;
 
 	/* dump core transaction and ticket info */
 	xfs_warn(mp, "transaction summary:");
@@ -2124,8 +2125,7 @@ xlog_print_trans(
 	xlog_print_tic_res(mp, tp->t_ticket);
 
 	/* dump each log item */
-	list_for_each_entry(lidp, &tp->t_items, lid_trans) {
-		struct xfs_log_item	*lip = lidp->lid_item;
+	list_for_each_entry(lip, &tp->t_items, li_trans) {
 		struct xfs_log_vec	*lv = lip->li_lv;
 		struct xfs_log_iovec	*vec;
 		int			i;

fs/xfs/xfs_log_cil.c

@@ -141,18 +141,17 @@ xlog_cil_alloc_shadow_bufs(
 	struct xlog		*log,
 	struct xfs_trans	*tp)
 {
-	struct xfs_log_item_desc *lidp;
+	struct xfs_log_item	*lip;
 
-	list_for_each_entry(lidp, &tp->t_items, lid_trans) {
-		struct xfs_log_item *lip = lidp->lid_item;
+	list_for_each_entry(lip, &tp->t_items, li_trans) {
 		struct xfs_log_vec *lv;
 		int	niovecs = 0;
 		int	nbytes = 0;
 		int	buf_size;
 		bool	ordered = false;
 
 		/* Skip items which aren't dirty in this transaction. */
-		if (!(lidp->lid_flags & XFS_LID_DIRTY))
+		if (!test_bit(XFS_LI_DIRTY, &lip->li_flags))
 			continue;
 
 		/* get number of vecs and size of data to be stored */
@@ -317,7 +316,7 @@ xlog_cil_insert_format_items(
 	int			*diff_len,
 	int			*diff_iovecs)
 {
-	struct xfs_log_item_desc *lidp;
+	struct xfs_log_item	*lip;
 
 
 	/* Bail out if we didn't find a log item.  */
@@ -326,15 +325,14 @@ xlog_cil_insert_format_items(
 		return;
 	}
 
-	list_for_each_entry(lidp, &tp->t_items, lid_trans) {
-		struct xfs_log_item *lip = lidp->lid_item;
+	list_for_each_entry(lip, &tp->t_items, li_trans) {
 		struct xfs_log_vec *lv;
 		struct xfs_log_vec *old_lv = NULL;
 		struct xfs_log_vec *shadow;
 		bool	ordered = false;
 
 		/* Skip items which aren't dirty in this transaction. */
-		if (!(lidp->lid_flags & XFS_LID_DIRTY))
+		if (!test_bit(XFS_LI_DIRTY, &lip->li_flags))
 			continue;
 
 		/*
@@ -406,7 +404,7 @@ xlog_cil_insert_items(
 {
 	struct xfs_cil		*cil = log->l_cilp;
 	struct xfs_cil_ctx	*ctx = cil->xc_ctx;
-	struct xfs_log_item_desc *lidp;
+	struct xfs_log_item	*lip;
 	int			len = 0;
 	int			diff_iovecs = 0;
 	int			iclog_space;
@@ -479,11 +477,10 @@ xlog_cil_insert_items(
 	 * We do this here so we only need to take the CIL lock once during
 	 * the transaction commit.
 	 */
-	list_for_each_entry(lidp, &tp->t_items, lid_trans) {
-		struct xfs_log_item	*lip = lidp->lid_item;
+	list_for_each_entry(lip, &tp->t_items, li_trans) {
 
 		/* Skip items which aren't dirty in this transaction. */
-		if (!(lidp->lid_flags & XFS_LID_DIRTY))
+		if (!test_bit(XFS_LI_DIRTY, &lip->li_flags))
 			continue;
 
 		/*

fs/xfs/xfs_super.c

@@ -1880,11 +1880,6 @@ xfs_init_zones(void)
 	if (!xfs_trans_zone)
 		goto out_destroy_ifork_zone;
 
-	xfs_log_item_desc_zone =
-		kmem_zone_init(sizeof(struct xfs_log_item_desc),
-			       "xfs_log_item_desc");
-	if (!xfs_log_item_desc_zone)
-		goto out_destroy_trans_zone;
 
 	/*
 	 * The size of the zone allocated buf log item is the maximum
@@ -1894,7 +1889,7 @@ xfs_init_zones(void)
 	xfs_buf_item_zone = kmem_zone_init(sizeof(struct xfs_buf_log_item),
 					   "xfs_buf_item");
 	if (!xfs_buf_item_zone)
-		goto out_destroy_log_item_desc_zone;
+		goto out_destroy_trans_zone;
 
 	xfs_efd_zone = kmem_zone_init((sizeof(xfs_efd_log_item_t) +
 			((XFS_EFD_MAX_FAST_EXTENTS - 1) *
@@ -1982,8 +1977,6 @@ xfs_init_zones(void)
 	kmem_zone_destroy(xfs_efd_zone);
  out_destroy_buf_item_zone:
 	kmem_zone_destroy(xfs_buf_item_zone);
- out_destroy_log_item_desc_zone:
-	kmem_zone_destroy(xfs_log_item_desc_zone);
  out_destroy_trans_zone:
 	kmem_zone_destroy(xfs_trans_zone);
  out_destroy_ifork_zone:
@@ -2022,7 +2015,6 @@ xfs_destroy_zones(void)
 	kmem_zone_destroy(xfs_efi_zone);
 	kmem_zone_destroy(xfs_efd_zone);
 	kmem_zone_destroy(xfs_buf_item_zone);
-	kmem_zone_destroy(xfs_log_item_desc_zone);
 	kmem_zone_destroy(xfs_trans_zone);
 	kmem_zone_destroy(xfs_ifork_zone);
 	kmem_zone_destroy(xfs_da_state_zone);

fs/xfs/xfs_trace.h

@@ -441,7 +441,6 @@ DECLARE_EVENT_CLASS(xfs_buf_item_class,
 		__field(unsigned, bli_recur)
 		__field(int, bli_refcount)
 		__field(unsigned, bli_flags)
-		__field(void *, li_desc)
 		__field(unsigned long, li_flags)
 	),
 	TP_fast_assign(
@@ -455,12 +454,11 @@ DECLARE_EVENT_CLASS(xfs_buf_item_class,
 		__entry->buf_hold = atomic_read(&bip->bli_buf->b_hold);
 		__entry->buf_pincount = atomic_read(&bip->bli_buf->b_pin_count);
 		__entry->buf_lockval = bip->bli_buf->b_sema.count;
-		__entry->li_desc = bip->bli_item.li_desc;
 		__entry->li_flags = bip->bli_item.li_flags;
 	),
 	TP_printk("dev %d:%d bno 0x%llx len 0x%zx hold %d pincount %d "
 		  "lock %d flags %s recur %d refcount %d bliflags %s "
-		  "lidesc %p liflags %s",
+		  "liflags %s",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
 		  (unsigned long long)__entry->buf_bno,
 		  __entry->buf_len,
@@ -471,7 +469,6 @@ DECLARE_EVENT_CLASS(xfs_buf_item_class,
 		  __entry->bli_recur,
 		  __entry->bli_refcount,
 		  __print_flags(__entry->bli_flags, "|", XFS_BLI_FLAGS),
-		  __entry->li_desc,
 		  __print_flags(__entry->li_flags, "|", XFS_LI_FLAGS))
 )
 

fs/xfs/xfs_trans.c

@@ -34,7 +34,6 @@
 #include "xfs_defer.h"
 
 kmem_zone_t	*xfs_trans_zone;
-kmem_zone_t	*xfs_log_item_desc_zone;
 
 #if defined(CONFIG_TRACEPOINTS)
 static void
@@ -734,77 +733,52 @@ xfs_trans_unreserve_and_mod_sb(
 	return;
 }
 
-/*
- * Add the given log item to the transaction's list of log items.
- *
- * The log item will now point to its new descriptor with its li_desc field.
- */
+/* Add the given log item to the transaction's list of log items. */
 void
 xfs_trans_add_item(
 	struct xfs_trans	*tp,
 	struct xfs_log_item	*lip)
 {
-	struct xfs_log_item_desc *lidp;
-
 	ASSERT(lip->li_mountp == tp->t_mountp);
 	ASSERT(lip->li_ailp == tp->t_mountp->m_ail);
+	ASSERT(list_empty(&lip->li_trans));
+	ASSERT(!test_bit(XFS_LI_DIRTY, &lip->li_flags));
 
-	lidp = kmem_zone_zalloc(xfs_log_item_desc_zone, KM_SLEEP | KM_NOFS);
-
-	lidp->lid_item = lip;
-	lidp->lid_flags = 0;
-	list_add_tail(&lidp->lid_trans, &tp->t_items);
-
-	lip->li_desc = lidp;
-
+	list_add_tail(&lip->li_trans, &tp->t_items);
 	trace_xfs_trans_add_item(tp, _RET_IP_);
 }
 
-STATIC void
-xfs_trans_free_item_desc(
-	struct xfs_log_item_desc *lidp)
-{
-	list_del_init(&lidp->lid_trans);
-	kmem_zone_free(xfs_log_item_desc_zone, lidp);
-}
-
 /*
- * Unlink and free the given descriptor.
+ * Unlink the log item from the transaction. the log item is no longer
+ * considered dirty in this transaction, as the linked transaction has
+ * finished, either by abort or commit completion.
  */
 void
 xfs_trans_del_item(
 	struct xfs_log_item	*lip)
 {
-	xfs_trans_free_item_desc(lip->li_desc);
-	lip->li_desc = NULL;
+	clear_bit(XFS_LI_DIRTY, &lip->li_flags);
+	list_del_init(&lip->li_trans);
 }
 
-/*
- * Unlock all of the items of a transaction and free all the descriptors
- * of that transaction.
- */
+/* Detach and unlock all of the items in a transaction */
 void
 xfs_trans_free_items(
 	struct xfs_trans	*tp,
 	xfs_lsn_t		commit_lsn,
 	bool			abort)
 {
-	struct xfs_log_item_desc *lidp, *next;
+	struct xfs_log_item	*lip, *next;
 
 	trace_xfs_trans_free_items(tp, _RET_IP_);
 
-	list_for_each_entry_safe(lidp, next, &tp->t_items, lid_trans) {
-		struct xfs_log_item	*lip = lidp->lid_item;
-
-		lip->li_desc = NULL;
-
+	list_for_each_entry_safe(lip, next, &tp->t_items, li_trans) {
+		xfs_trans_del_item(lip);
 		if (commit_lsn != NULLCOMMITLSN)
 			lip->li_ops->iop_committing(lip, commit_lsn);
 		if (abort)
 			set_bit(XFS_LI_ABORTED, &lip->li_flags);
 		lip->li_ops->iop_unlock(lip);
-
-		xfs_trans_free_item_desc(lidp);
 	}
 }
 
@@ -1052,10 +1026,10 @@ xfs_trans_cancel(
 	}
 #ifdef DEBUG
 	if (!dirty && !XFS_FORCED_SHUTDOWN(mp)) {
-		struct xfs_log_item_desc *lidp;
+		struct xfs_log_item *lip;
 
-		list_for_each_entry(lidp, &tp->t_items, lid_trans)
-			ASSERT(!(lidp->lid_item->li_type == XFS_LI_EFD));
+		list_for_each_entry(lip, &tp->t_items, li_trans)
+			ASSERT(!(lip->li_type == XFS_LI_EFD));
 	}
 #endif
 	xfs_trans_unreserve_and_mod_sb(tp);

fs/xfs/xfs_trans.h

@@ -27,7 +27,6 @@ struct xfs_efi_log_item;
 struct xfs_inode;
 struct xfs_item_ops;
 struct xfs_log_iovec;
-struct xfs_log_item_desc;
 struct xfs_mount;
 struct xfs_trans;
 struct xfs_trans_res;
@@ -43,8 +42,8 @@ struct xfs_bud_log_item;
 
 typedef struct xfs_log_item {
 	struct list_head		li_ail;		/* AIL pointers */
+	struct list_head		li_trans;	/* transaction list */
 	xfs_lsn_t			li_lsn;		/* last on-disk lsn */
-	struct xfs_log_item_desc	*li_desc;	/* ptr to current desc*/
 	struct xfs_mount		*li_mountp;	/* ptr to fs mount */
 	struct xfs_ail			*li_ailp;	/* ptr to AIL */
 	uint				li_type;	/* item type */
@@ -72,11 +71,13 @@ typedef struct xfs_log_item {
 #define	XFS_LI_IN_AIL	0
 #define	XFS_LI_ABORTED	1
 #define	XFS_LI_FAILED	2
+#define	XFS_LI_DIRTY	3	/* log item dirty in transaction */
 
 #define XFS_LI_FLAGS \
 	{ (1 << XFS_LI_IN_AIL),		"IN_AIL" }, \
 	{ (1 << XFS_LI_ABORTED),	"ABORTED" }, \
-	{ (1 << XFS_LI_FAILED),		"FAILED" }
+	{ (1 << XFS_LI_FAILED),		"FAILED" }, \
+	{ (1 << XFS_LI_DIRTY),		"DIRTY" }
 
 struct xfs_item_ops {
 	void (*iop_size)(xfs_log_item_t *, int *, int *);
@@ -248,7 +249,6 @@ void		xfs_trans_buf_copy_type(struct xfs_buf *dst_bp,
 					struct xfs_buf *src_bp);
 
 extern kmem_zone_t	*xfs_trans_zone;
-extern kmem_zone_t	*xfs_log_item_desc_zone;
 
 /* rmap updates */
 enum xfs_rmap_intent_type;