[PATCH 9/9] xfs: only allocate free space bitmap for xattr scrub if needed

From: "Darrick J. Wong" <djwong@kernel.org>
To: djwong@kernel.org
Cc: linux-xfs@vger.kernel.org
Subject: [PATCH 9/9] xfs: only allocate free space bitmap for xattr scrub if needed
Date: Sun, 02 Oct 2022 11:20:41 -0700	[thread overview]
Message-ID: <166473484120.1085108.12625299349355602768.stgit@magnolia> (raw)
In-Reply-To: <166473483982.1085108.101544412199880535.stgit@magnolia>

From: Darrick J. Wong <djwong@kernel.org>

The free space bitmap is only required if we're going to check the
bestfree space at the end of an xattr leaf block.  Therefore, we can
reduce the memory requirements of this scrubber if we can determine that
the xattr is in short format.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/scrub/attr.c |   31 ++++++++++++++++++++++++++++---
 1 file changed, 28 insertions(+), 3 deletions(-)

diff --git a/fs/xfs/scrub/attr.c b/fs/xfs/scrub/attr.c
index f6eb6070488b..b315a499ba32 100644
--- a/fs/xfs/scrub/attr.c
+++ b/fs/xfs/scrub/attr.c
@@ -37,6 +37,29 @@ xchk_xattr_buf_cleanup(
 	ab->value_sz = 0;
 }
 
+/*
+ * Allocate the free space bitmap if we're trying harder; there are leaf blocks
+ * in the attr fork; or we can't tell if there are leaf blocks.
+ */
+static inline bool
+xchk_xattr_want_freemap(
+	struct xfs_scrub	*sc)
+{
+	struct xfs_ifork	*ifp;
+
+	if (sc->flags & XCHK_TRY_HARDER)
+		return true;
+
+	if (!sc->ip)
+		return true;
+
+	ifp = xfs_ifork_ptr(sc->ip, XFS_ATTR_FORK);
+	if (!ifp)
+		return false;
+
+	return xfs_ifork_has_extents(ifp);
+}
+
 /*
  * Allocate enough memory to hold an attr value and attr block bitmaps,
  * reallocating the buffer if necessary.  Buffer contents are not preserved
@@ -66,9 +89,11 @@ xchk_setup_xattr_buf(
 	if (!ab->usedmap)
 		return -ENOMEM;
 
-	ab->freemap = kvmalloc(bmp_sz, XCHK_GFP_FLAGS);
-	if (!ab->freemap)
-		return -ENOMEM;
+	if (xchk_xattr_want_freemap(sc)) {
+		ab->freemap = kvmalloc(bmp_sz, XCHK_GFP_FLAGS);
+		if (!ab->freemap)
+			return -ENOMEM;
+	}
 
 resize_value:
 	if (ab->value_sz >= value_size)

