xfs: Compute bmap extent alignments in a separate function

This commit moves over the code which computes stripe alignment and
extent size hint alignment into a separate function. Apart from
xfs_bmap_btalloc(), the new function will be used by another function
introduced in a future commit.

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/libxfs/xfs_bmap.c

@@ -3463,13 +3463,59 @@ xfs_bmap_btalloc_accounting(
 		args->len);
 }
 
+static int
+xfs_bmap_compute_alignments(
+	struct xfs_bmalloca	*ap,
+	struct xfs_alloc_arg	*args)
+{
+	struct xfs_mount	*mp = args->mp;
+	xfs_extlen_t		align = 0; /* minimum allocation alignment */
+	int			stripe_align = 0;
+	int			error;
+
+	/* stripe alignment for allocation is determined by mount parameters */
+	if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC))
+		stripe_align = mp->m_swidth;
+	else if (mp->m_dalign)
+		stripe_align = mp->m_dalign;
+
+	if (ap->flags & XFS_BMAPI_COWFORK)
+		align = xfs_get_cowextsz_hint(ap->ip);
+	else if (ap->datatype & XFS_ALLOC_USERDATA)
+		align = xfs_get_extsz_hint(ap->ip);
+	if (align) {
+		error = xfs_bmap_extsize_align(mp, &ap->got, &ap->prev,
+						align, 0, ap->eof, 0, ap->conv,
+						&ap->offset, &ap->length);
+		ASSERT(!error);
+		ASSERT(ap->length);
+	}
+
+	/* apply extent size hints if obtained earlier */
+	if (align) {
+		args->prod = align;
+		div_u64_rem(ap->offset, args->prod, &args->mod);
+		if (args->mod)
+			args->mod = args->prod - args->mod;
+	} else if (mp->m_sb.sb_blocksize >= PAGE_SIZE) {
+		args->prod = 1;
+		args->mod = 0;
+	} else {
+		args->prod = PAGE_SIZE >> mp->m_sb.sb_blocklog;
+		div_u64_rem(ap->offset, args->prod, &args->mod);
+		if (args->mod)
+			args->mod = args->prod - args->mod;
+	}
+
+	return stripe_align;
+}
+
 STATIC int
 xfs_bmap_btalloc(
 	struct xfs_bmalloca	*ap)	/* bmap alloc argument struct */
 {
 	xfs_mount_t	*mp;		/* mount point structure */
 	xfs_alloctype_t	atype = 0;	/* type for allocation routines */
-	xfs_extlen_t	align = 0;	/* minimum allocation alignment */
 	xfs_agnumber_t	fb_agno;	/* ag number of ap->firstblock */
 	xfs_agnumber_t	ag;
 	xfs_alloc_arg_t	args;
@@ -3489,25 +3535,11 @@ xfs_bmap_btalloc(
 
 	mp = ap->ip->i_mount;
 
-	/* stripe alignment for allocation is determined by mount parameters */
+	memset(&args, 0, sizeof(args));
-	stripe_align = 0;
+	args.tp = ap->tp;
-	if (mp->m_swidth && (mp->m_flags & XFS_MOUNT_SWALLOC))
+	args.mp = mp;
-		stripe_align = mp->m_swidth;
-	else if (mp->m_dalign)
-		stripe_align = mp->m_dalign;
-
-	if (ap->flags & XFS_BMAPI_COWFORK)
-		align = xfs_get_cowextsz_hint(ap->ip);
-	else if (ap->datatype & XFS_ALLOC_USERDATA)
-		align = xfs_get_extsz_hint(ap->ip);
-	if (align) {
-		error = xfs_bmap_extsize_align(mp, &ap->got, &ap->prev,
-						align, 0, ap->eof, 0, ap->conv,
-						&ap->offset, &ap->length);
-		ASSERT(!error);
-		ASSERT(ap->length);
-	}
 
+	stripe_align = xfs_bmap_compute_alignments(ap, &args);
 
 	nullfb = ap->tp->t_firstblock == NULLFSBLOCK;
 	fb_agno = nullfb ? NULLAGNUMBER : XFS_FSB_TO_AGNO(mp,
@@ -3538,9 +3570,6 @@ xfs_bmap_btalloc(
 	 * Normal allocation, done through xfs_alloc_vextent.
 	 */
 	tryagain = isaligned = 0;
-	memset(&args, 0, sizeof(args));
-	args.tp = ap->tp;
-	args.mp = mp;
 	args.fsbno = ap->blkno;
 	args.oinfo = XFS_RMAP_OINFO_SKIP_UPDATE;
 
@@ -3571,21 +3600,7 @@ xfs_bmap_btalloc(
 		args.total = ap->total;
 		args.minlen = ap->minlen;
 	}
-	/* apply extent size hints if obtained earlier */
+
-	if (align) {
-		args.prod = align;
-		div_u64_rem(ap->offset, args.prod, &args.mod);
-		if (args.mod)
-			args.mod = args.prod - args.mod;
-	} else if (mp->m_sb.sb_blocksize >= PAGE_SIZE) {
-		args.prod = 1;
-		args.mod = 0;
-	} else {
-		args.prod = PAGE_SIZE >> mp->m_sb.sb_blocklog;
-		div_u64_rem(ap->offset, args.prod, &args.mod);
-		if (args.mod)
-			args.mod = args.prod - args.mod;
-	}
 	/*
 	 * If we are not low on available data blocks, and the underlying
 	 * logical volume manager is a stripe, and the file offset is zero then