[PATCH 2/5] xfs: factor data block addition from xfs_dir2_node_addname_int()

[Dave Chinner <david@fromorbit.com>]

From: Dave Chinner <dchinner@redhat.com>

Factor out the code that adds a data block to a directory from
xfs_dir2_node_addname_int(). This makes the code flow cleaner and
more obvious and provides clear isolation of upcoming optimsations.

Signed-off-By: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_dir2_node.c | 324 +++++++++++++++++-----------------
 1 file changed, 158 insertions(+), 166 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_dir2_node.c b/fs/xfs/libxfs/xfs_dir2_node.c
index e40986cc0759..cc1f1c505a2b 100644
--- a/fs/xfs/libxfs/xfs_dir2_node.c
+++ b/fs/xfs/libxfs/xfs_dir2_node.c
@@ -1608,6 +1608,129 @@ xfs_dir2_leafn_unbalance(
 	xfs_dir3_leaf_check(dp, drop_blk->bp);
 }
 
+/*
+ * Add a new data block to the directory at the free space index that the caller
+ * has specified.
+ */
+static int
+xfs_dir2_node_add_datablk(
+	struct xfs_da_args	*args,
+	struct xfs_da_state_blk	*fblk,
+	xfs_dir2_db_t		*dbno,
+	struct xfs_buf		**dbpp,
+	struct xfs_buf		**fbpp,
+	int			*findex)
+{
+	struct xfs_inode	*dp = args->dp;
+	struct xfs_trans	*tp = args->trans;
+	struct xfs_mount	*mp = dp->i_mount;
+	struct xfs_dir3_icfree_hdr freehdr;
+	struct xfs_dir2_data_free *bf;
+	struct xfs_dir2_data_hdr *hdr;
+	struct xfs_dir2_free	*free = NULL;
+	xfs_dir2_db_t		fbno;
+	struct xfs_buf		*fbp;
+	struct xfs_buf		*dbp;
+	__be16			*bests = NULL;
+	int			error;
+
+	/* Not allowed to allocate, return failure. */
+	if ((args->op_flags & XFS_DA_OP_JUSTCHECK) || args->total == 0)
+		return -ENOSPC;
+
+	/* Allocate and initialize the new data block.  */
+	error = xfs_dir2_grow_inode(args, XFS_DIR2_DATA_SPACE, dbno);
+	if (error)
+		return error;
+	error = xfs_dir3_data_init(args, *dbno, &dbp);
+	if (error)
+		return error;
+
+	/*
+	 * Get the freespace block corresponding to the data block
+	 * that was just allocated.
+	 */
+	fbno = dp->d_ops->db_to_fdb(args->geo, *dbno);
+	error = xfs_dir2_free_try_read(tp, dp,
+			       xfs_dir2_db_to_da(args->geo, fbno), &fbp);
+	if (error)
+		return error;
+
+	/*
+	 * If there wasn't a freespace block, the read will
+	 * return a NULL fbp.  Allocate and initialize a new one.
+	 */
+	if (!fbp) {
+		error = xfs_dir2_grow_inode(args, XFS_DIR2_FREE_SPACE, &fbno);
+		if (error)
+			return error;
+
+		if (dp->d_ops->db_to_fdb(args->geo, *dbno) != fbno) {
+			xfs_alert(mp,
+"%s: dir ino %llu needed freesp block %lld for data block %lld, got %lld",
+				__func__, (unsigned long long)dp->i_ino,
+				(long long)dp->d_ops->db_to_fdb(args->geo, *dbno),
+				(long long)*dbno, (long long)fbno);
+			if (fblk) {
+				xfs_alert(mp,
+			" fblk "PTR_FMT" blkno %llu index %d magic 0x%x",
+					fblk, (unsigned long long)fblk->blkno,
+					fblk->index, fblk->magic);
+			} else {
+				xfs_alert(mp, " ... fblk is NULL");
+			}
+			XFS_ERROR_REPORT(__func__, XFS_ERRLEVEL_LOW, mp);
+			return -EFSCORRUPTED;
+		}
+
+		/* Get a buffer for the new block. */
+		error = xfs_dir3_free_get_buf(args, fbno, &fbp);
+		if (error)
+			return error;
+		free = fbp->b_addr;
+		bests = dp->d_ops->free_bests_p(free);
+		dp->d_ops->free_hdr_from_disk(&freehdr, free);
+
+		/* Remember the first slot as our empty slot. */
+		freehdr.firstdb = (fbno - xfs_dir2_byte_to_db(args->geo,
+							XFS_DIR2_FREE_OFFSET)) *
+				dp->d_ops->free_max_bests(args->geo);
+	} else {
+		free = fbp->b_addr;
+		bests = dp->d_ops->free_bests_p(free);
+		dp->d_ops->free_hdr_from_disk(&freehdr, free);
+	}
+
+	/* Set the freespace block index from the data block number. */
+	*findex = dp->d_ops->db_to_fdindex(args->geo, *dbno);
+
+	/* Extend the freespace table if the new data block is off the end. */
+	if (*findex >= freehdr.nvalid) {
+		ASSERT(*findex < dp->d_ops->free_max_bests(args->geo));
+		freehdr.nvalid = *findex + 1;
+		bests[*findex] = cpu_to_be16(NULLDATAOFF);
+	}
+
+	/*
+	 * If this entry was for an empty data block (this should always be
+	 * true) then update the header.
+	 */
+	if (bests[*findex] == cpu_to_be16(NULLDATAOFF)) {
+		freehdr.nused++;
+		dp->d_ops->free_hdr_to_disk(fbp->b_addr, &freehdr);
+		xfs_dir2_free_log_header(args, fbp);
+	}
+
+	/* Update the freespace value for the new block in the table. */
+	hdr = dbp->b_addr;
+	bf = dp->d_ops->data_bestfree_p(hdr);
+	bests[*findex] = bf[0].length;
+
+	*dbpp = dbp;
+	*fbpp = fbp;
+	return 0;
+}
+
 /*
  * Add the data entry for a node-format directory name addition.
  * The leaf entry is added in xfs_dir2_leafn_add.
@@ -1632,10 +1755,9 @@ xfs_dir2_node_addname_int(
 	xfs_dir2_db_t		ifbno;		/* initial freespace block no */
 	xfs_dir2_db_t		lastfbno=0;	/* highest freespace block no */
 	int			length;		/* length of the new entry */
-	int			logfree;	/* need to log free entry */
-	xfs_mount_t		*mp;		/* filesystem mount point */
-	int			needlog;	/* need to log data header */
-	int			needscan;	/* need to rescan data frees */
+	int			logfree = 0;	/* need to log free entry */
+	int			needlog = 0;	/* need to log data header */
+	int			needscan = 0;	/* need to rescan data frees */
 	__be16			*tagp;		/* data entry tag pointer */
 	xfs_trans_t		*tp;		/* transaction pointer */
 	__be16			*bests;
@@ -1644,7 +1766,6 @@ xfs_dir2_node_addname_int(
 	xfs_dir2_data_aoff_t	aoff;
 
 	dp = args->dp;
-	mp = dp->i_mount;
 	tp = args->trans;
 	length = dp->d_ops->data_entsize(args->namelen);
 	/*
@@ -1673,6 +1794,7 @@ xfs_dir2_node_addname_int(
 			ASSERT(be16_to_cpu(bests[findex]) != NULLDATAOFF);
 			ASSERT(be16_to_cpu(bests[findex]) >= length);
 			dbno = freehdr.firstdb + findex;
+			goto found_block;
 		} else {
 			/*
 			 * The data block looked at didn't have enough room.
@@ -1774,168 +1896,46 @@ xfs_dir2_node_addname_int(
 			}
 		}
 	}
+
 	/*
 	 * If we don't have a data block, we need to allocate one and make
 	 * the freespace entries refer to it.
 	 */
-	if (unlikely(dbno == -1)) {
-		/*
-		 * Not allowed to allocate, return failure.
-		 */
-		if ((args->op_flags & XFS_DA_OP_JUSTCHECK) || args->total == 0)
-			return -ENOSPC;
-
-		/*
-		 * Allocate and initialize the new data block.
-		 */
-		if (unlikely((error = xfs_dir2_grow_inode(args,
-							 XFS_DIR2_DATA_SPACE,
-							 &dbno)) ||
-		    (error = xfs_dir3_data_init(args, dbno, &dbp))))
-			return error;
-
-		/*
-		 * If (somehow) we have a freespace block, get rid of it.
-		 */
-		if (fbp)
-			xfs_trans_brelse(tp, fbp);
-		if (fblk && fblk->bp)
-			fblk->bp = NULL;
-
-		/*
-		 * Get the freespace block corresponding to the data block
-		 * that was just allocated.
-		 */
-		fbno = dp->d_ops->db_to_fdb(args->geo, dbno);
-		error = xfs_dir2_free_try_read(tp, dp,
-				       xfs_dir2_db_to_da(args->geo, fbno),
-				       &fbp);
+	if (dbno == -1) {
+		error = xfs_dir2_node_add_datablk(args, fblk, &dbno, &dbp, &fbp,
+						  &findex);
 		if (error)
 			return error;
 
-		/*
-		 * If there wasn't a freespace block, the read will
-		 * return a NULL fbp.  Allocate and initialize a new one.
-		 */
-		if (!fbp) {
-			error = xfs_dir2_grow_inode(args, XFS_DIR2_FREE_SPACE,
-						    &fbno);
-			if (error)
-				return error;
-
-			if (dp->d_ops->db_to_fdb(args->geo, dbno) != fbno) {
-				xfs_alert(mp,
-"%s: dir ino %llu needed freesp block %lld for data block %lld, got %lld ifbno %llu lastfbno %d",
-					__func__, (unsigned long long)dp->i_ino,
-					(long long)dp->d_ops->db_to_fdb(
-								args->geo, dbno),
-					(long long)dbno, (long long)fbno,
-					(unsigned long long)ifbno, lastfbno);
-				if (fblk) {
-					xfs_alert(mp,
-				" fblk "PTR_FMT" blkno %llu index %d magic 0x%x",
-						fblk,
-						(unsigned long long)fblk->blkno,
-						fblk->index,
-						fblk->magic);
-				} else {
-					xfs_alert(mp, " ... fblk is NULL");
-				}
-				XFS_ERROR_REPORT("xfs_dir2_node_addname_int",
-						 XFS_ERRLEVEL_LOW, mp);
-				return -EFSCORRUPTED;
-			}
-
-			/*
-			 * Get a buffer for the new block.
-			 */
-			error = xfs_dir3_free_get_buf(args, fbno, &fbp);
-			if (error)
-				return error;
-			free = fbp->b_addr;
-			bests = dp->d_ops->free_bests_p(free);
-			dp->d_ops->free_hdr_from_disk(&freehdr, free);
-
-			/*
-			 * Remember the first slot as our empty slot.
-			 */
-			freehdr.firstdb =
-				(fbno - xfs_dir2_byte_to_db(args->geo,
-							XFS_DIR2_FREE_OFFSET)) *
-					dp->d_ops->free_max_bests(args->geo);
-		} else {
-			free = fbp->b_addr;
-			bests = dp->d_ops->free_bests_p(free);
-			dp->d_ops->free_hdr_from_disk(&freehdr, free);
-		}
+		/* setup current free block buffer */
+		free = fbp->b_addr;
 
-		/*
-		 * Set the freespace block index from the data block number.
-		 */
-		findex = dp->d_ops->db_to_fdindex(args->geo, dbno);
-		/*
-		 * If it's after the end of the current entries in the
-		 * freespace block, extend that table.
-		 */
-		if (findex >= freehdr.nvalid) {
-			ASSERT(findex < dp->d_ops->free_max_bests(args->geo));
-			freehdr.nvalid = findex + 1;
-			/*
-			 * Tag new entry so nused will go up.
-			 */
-			bests[findex] = cpu_to_be16(NULLDATAOFF);
-		}
-		/*
-		 * If this entry was for an empty data block
-		 * (this should always be true) then update the header.
-		 */
-		if (bests[findex] == cpu_to_be16(NULLDATAOFF)) {
-			freehdr.nused++;
-			dp->d_ops->free_hdr_to_disk(fbp->b_addr, &freehdr);
-			xfs_dir2_free_log_header(args, fbp);
-		}
-		/*
-		 * Update the real value in the table.
-		 * We haven't allocated the data entry yet so this will
-		 * change again.
-		 */
-		hdr = dbp->b_addr;
-		bf = dp->d_ops->data_bestfree_p(hdr);
-		bests[findex] = bf[0].length;
+		/* we're going to have to log the free block index later */
 		logfree = 1;
-	}
-	/*
-	 * We had a data block so we don't have to make a new one.
-	 */
-	else {
-		/*
-		 * If just checking, we succeeded.
-		 */
+	} else {
+found_block:
+		/* If just checking, we succeeded. */
 		if (args->op_flags & XFS_DA_OP_JUSTCHECK)
 			return 0;
 
-		/*
-		 * Read the data block in.
-		 */
+		/* Read the data block in. */
 		error = xfs_dir3_data_read(tp, dp,
 					   xfs_dir2_db_to_da(args->geo, dbno),
 					   -1, &dbp);
 		if (error)
 			return error;
-		hdr = dbp->b_addr;
-		bf = dp->d_ops->data_bestfree_p(hdr);
-		logfree = 0;
 	}
+
+	/* setup for data block up now */
+	hdr = dbp->b_addr;
+	bf = dp->d_ops->data_bestfree_p(hdr);
 	ASSERT(be16_to_cpu(bf[0].length) >= length);
-	/*
-	 * Point to the existing unused space.
-	 */
+
+	/* Point to the existing unused space. */
 	dup = (xfs_dir2_data_unused_t *)
 	      ((char *)hdr + be16_to_cpu(bf[0].offset));
-	needscan = needlog = 0;
-	/*
-	 * Mark the first part of the unused space, inuse for us.
-	 */
+
+	/* Mark the first part of the unused space, inuse for us. */
 	aoff = (xfs_dir2_data_aoff_t)((char *)dup - (char *)hdr);
 	error = xfs_dir2_data_use_free(args, dbp, dup, aoff, length,
 			&needlog, &needscan);
@@ -1943,9 +1943,8 @@ xfs_dir2_node_addname_int(
 		xfs_trans_brelse(tp, dbp);
 		return error;
 	}
-	/*
-	 * Fill in the new entry and log it.
-	 */
+
+	/* Fill in the new entry and log it. */
 	dep = (xfs_dir2_data_entry_t *)dup;
 	dep->inumber = cpu_to_be64(args->inumber);
 	dep->namelen = args->namelen;
@@ -1954,32 +1953,25 @@ xfs_dir2_node_addname_int(
 	tagp = dp->d_ops->data_entry_tag_p(dep);
 	*tagp = cpu_to_be16((char *)dep - (char *)hdr);
 	xfs_dir2_data_log_entry(args, dbp, dep);
-	/*
-	 * Rescan the block for bestfree if needed.
-	 */
+
+	/* Rescan the freespace and log the data block if needed. */
 	if (needscan)
 		xfs_dir2_data_freescan(dp, hdr, &needlog);
-	/*
-	 * Log the data block header if needed.
-	 */
 	if (needlog)
 		xfs_dir2_data_log_header(args, dbp);
-	/*
-	 * If the freespace entry is now wrong, update it.
-	 */
-	bests = dp->d_ops->free_bests_p(free); /* gcc is so stupid */
-	if (be16_to_cpu(bests[findex]) != be16_to_cpu(bf[0].length)) {
+
+	/* If the freespace block entry is now wrong, update it. */
+	bests = dp->d_ops->free_bests_p(free);
+	if (bests[findex] != bf[0].length) {
 		bests[findex] = bf[0].length;
 		logfree = 1;
 	}
-	/*
-	 * Log the freespace entry if needed.
-	 */
+
+	/* Log the freespace entry if needed. */
 	if (logfree)
 		xfs_dir2_free_log_bests(args, fbp, findex, findex);
-	/*
-	 * Return the data block and offset in args, then drop the data block.
-	 */
+
+	/* Return the data block and offset in args. */
 	args->blkno = (xfs_dablk_t)dbno;
 	args->index = be16_to_cpu(*tagp);
 	return 0;
-- 
2.23.0.rc1