xfs: move xfs_bmap_btalloc_filestreams() to xfs_filestreams.c

xfs_bmap_btalloc_filestreams() calls two filestreams functions to
select the AG to allocate from. Both those functions end up in
the same selection function that iterates all AGs multiple times.
Worst case, xfs_bmap_btalloc_filestreams() can iterate all AGs 4
times just to select the initial AG to allocate in.

Move the AG selection to fs/xfs/xfs_filestreams.c as a single
interface so that the inefficient AG interation is contained
entirely within the filestreams code. This will allow the
implementation to be simplified and made more efficient in future
patches.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

2 files changed, 14 insertions, 83 deletions

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 16628fdbcd55..11facb8a6b3a 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -3222,68 +3222,6 @@ xfs_bmap_btalloc_select_lengths(
 	return error;
 }
 
-static int
-xfs_bmap_btalloc_filestreams_select_lengths(
-	struct xfs_bmalloca	*ap,
-	struct xfs_alloc_arg	*args,
-	xfs_extlen_t		*blen)
-{
-	struct xfs_mount	*mp = ap->ip->i_mount;
-	struct xfs_perag	*pag;
-	xfs_agnumber_t		start_agno;
-	int			error;
-
-	args->total = ap->total;
-
-	start_agno = XFS_FSB_TO_AGNO(mp, ap->blkno);
-	if (start_agno == NULLAGNUMBER)
-		start_agno = 0;
-
-	pag = xfs_perag_grab(mp, start_agno);
-	if (pag) {
-		error = xfs_bmap_longest_free_extent(pag, args->tp, blen);
-		xfs_perag_rele(pag);
-		if (error) {
-			if (error != -EAGAIN)
-				return error;
-			*blen = 0;
-		}
-	}
-
-	if (*blen < args->maxlen) {
-		xfs_agnumber_t	agno = start_agno;
-
-		error = xfs_filestream_new_ag(ap, &agno);
-		if (error)
-			return error;
-		if (agno == NULLAGNUMBER)
-			goto out_select;
-
-		pag = xfs_perag_grab(mp, agno);
-		if (!pag)
-			goto out_select;
-
-		error = xfs_bmap_longest_free_extent(pag, args->tp, blen);
-		xfs_perag_rele(pag);
-		if (error) {
-			if (error != -EAGAIN)
-				return error;
-			*blen = 0;
-		}
-		start_agno = agno;
-	}
-
-out_select:
-	args->minlen = xfs_bmap_select_minlen(ap, args, *blen);
-
-	/*
-	 * Set the failure fallback case to look in the selected AG as stream
-	 * may have moved.
-	 */
-	ap->blkno = args->fsbno = XFS_AGB_TO_FSB(mp, start_agno, 0);
-	return 0;
-}
-
 /* Update all inode and quota accounting for the allocation we just did. */
 static void
 xfs_bmap_btalloc_accounting(
@@ -3577,7 +3515,7 @@ xfs_bmap_btalloc_at_eof(
  * transaction that we are critically low on space so they don't waste time on
  * allocation modes that are unlikely to succeed.
  */
-static int
+int
 xfs_bmap_btalloc_low_space(
 	struct xfs_bmalloca	*ap,
 	struct xfs_alloc_arg	*args)
@@ -3606,36 +3544,25 @@ xfs_bmap_btalloc_filestreams(
 	struct xfs_alloc_arg	*args,
 	int			stripe_align)
 {
-	xfs_agnumber_t		agno = xfs_filestream_lookup_ag(ap->ip);
 	xfs_extlen_t		blen = 0;
 	int			error;
 
-	/* Determine the initial block number we will target for allocation. */
-	if (agno == NULLAGNUMBER)
-		agno = 0;
-	ap->blkno = XFS_AGB_TO_FSB(args->mp, agno, 0);
-	xfs_bmap_adjacent(ap);
+
+	error = xfs_filestream_select_ag(ap, args, &blen);
+	if (error)
+		return error;
 
 	/*
-	 * If there is very little free space before we start a
-	 * filestreams allocation, we're almost guaranteed to fail to
-	 * find an AG with enough contiguous free space to succeed, so
-	 * just go straight to the low space algorithm.
+	 * If we are in low space mode, then optimal allocation will fail so
+	 * prepare for minimal allocation and jump to the low space algorithm
+	 * immediately.
 	 */
 	if (ap->tp->t_flags & XFS_TRANS_LOWMODE) {
 		args->minlen = ap->minlen;
-		return xfs_bmap_btalloc_low_space(ap, args);
+		goto out_low_space;
 	}
 
-	/*
-	 * Search for an allocation group with a single extent large enough for
-	 * the request.  If one isn't found, then adjust the minimum allocation
-	 * size to the largest space found.
-	 */
-	error = xfs_bmap_btalloc_filestreams_select_lengths(ap, args, &blen);
-	if (error)
-		return error;
-
+	args->minlen = xfs_bmap_select_minlen(ap, args, blen);
 	if (ap->aeof) {
 		error = xfs_bmap_btalloc_at_eof(ap, args, blen, stripe_align,
 				true);
@@ -3647,6 +3574,7 @@ xfs_bmap_btalloc_filestreams(
 	if (error || args->fsbno != NULLFSBLOCK)
 		return error;
 
+out_low_space:
 	return xfs_bmap_btalloc_low_space(ap, args);
 }
 
diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h
index b52cfdcb9320..dd08361ca5a6 100644
--- a/fs/xfs/libxfs/xfs_bmap.h
+++ b/fs/xfs/libxfs/xfs_bmap.h
@@ -12,6 +12,7 @@ struct xfs_ifork;
 struct xfs_inode;
 struct xfs_mount;
 struct xfs_trans;
+struct xfs_alloc_arg;
 
 /*
  * Argument structure for xfs_bmap_alloc.
@@ -224,6 +225,8 @@ int	xfs_bmap_add_extent_unwritten_real(struct xfs_trans *tp,
 		struct xfs_bmbt_irec *new, int *logflagsp);
 xfs_extlen_t xfs_bmapi_minleft(struct xfs_trans *tp, struct xfs_inode *ip,
 		int fork);
+int	xfs_bmap_btalloc_low_space(struct xfs_bmalloca *ap,
+		struct xfs_alloc_arg *args);
 
 enum xfs_bmap_intent_type {
 	XFS_BMAP_MAP = 1,