xfs: flush delalloc blocks on ENOSPC in xfs_trans_alloc_icreate

xfs_trans_alloc_icreate() can fail with ENOSPC when delalloc
reservations have consumed most of the available block count
(fdblocks).  xfs_trans_alloc() already retries internally with
xfs_blockgc_flush_all(), but that only trims post-EOF speculative
preallocation and may not free enough space for the transaction
reservation.

Add a retry with xfs_flush_inodes() when xfs_trans_alloc() returns
ENOSPC.  This forces writeback of all dirty inodes via
sync_inodes_sb(), converting delalloc reservations to real
allocations and freeing the over-reserved portion back to fdblocks.

This fixes all callers of xfs_trans_alloc_icreate() and removes
the existing caller-level retry from xfs_create(), which is now
handled centrally.

Signed-off-by: Ravi Singh <ravising@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

Author: Ravi Singh

fs/xfs/xfs_inode.c

@@ -699,12 +699,6 @@ xfs_create(
 	 */
 	error = xfs_trans_alloc_icreate(mp, tres, udqp, gdqp, pdqp, resblks,
 			&tp);
-	if (error == -ENOSPC) {
-		/* flush outstanding delalloc blocks and retry */
-		xfs_flush_inodes(mp);
-		error = xfs_trans_alloc_icreate(mp, tres, udqp, gdqp, pdqp,
-				resblks, &tp);
-	}
 	if (error)
 		goto out_parent;
 

fs/xfs/xfs_trans.c

@@ -1199,10 +1199,21 @@ xfs_trans_alloc_icreate(
 {
 	struct xfs_trans	*tp;
 	bool			retried = false;
+	bool			flushed = false;
 	int			error;
 
 retry:
 	error = xfs_trans_alloc(mp, resv, dblocks, 0, 0, &tp);
+	if (error == -ENOSPC && !flushed) {
+		/*
+		 * Flush all delalloc blocks to reclaim space from speculative
+		 * preallocation.  This is similar to the quota retry below
+		 * but targets FS-wide ENOSPC.
+		 */
+		xfs_flush_inodes(mp);
+		flushed = true;
+		goto retry;
+	}
 	if (error)
 		return error;