[PATCH 02/30] xfs: create block pointer check functions

From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: darrick.wong@oracle.com
Cc: linux-xfs@vger.kernel.org
Subject: [PATCH 02/30] xfs: create block pointer check functions
Date: Wed, 11 Oct 2017 18:40:55 -0700	[thread overview]
Message-ID: <150777245581.1724.14031376814151145502.stgit@magnolia> (raw)
In-Reply-To: <150777244315.1724.6916081372861799350.stgit@magnolia>

From: Darrick J. Wong <darrick.wong@oracle.com>

Create some helper functions to check that a block pointer points
within the filesystem (or AG) and doesn't point at static metadata.
We will use this for scrub.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_alloc.c    |   49 ++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/libxfs/xfs_alloc.h    |    4 +++
 fs/xfs/libxfs/xfs_rtbitmap.c |   12 ++++++++++
 fs/xfs/xfs_rtalloc.h         |    2 ++
 4 files changed, 67 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index 744dcae..bd3a943 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -2923,3 +2923,52 @@ xfs_alloc_query_all(
 	query.fn = fn;
 	return xfs_btree_query_all(cur, xfs_alloc_query_range_helper, &query);
 }
+
+/* Find the size of the AG, in blocks. */
+xfs_agblock_t
+xfs_ag_block_count(
+	struct xfs_mount	*mp,
+	xfs_agnumber_t		agno)
+{
+	ASSERT(agno < mp->m_sb.sb_agcount);
+
+	if (agno < mp->m_sb.sb_agcount - 1)
+		return mp->m_sb.sb_agblocks;
+	return mp->m_sb.sb_dblocks - (agno * mp->m_sb.sb_agblocks);
+}
+
+/*
+ * Verify that an AG block number pointer neither points outside the AG
+ * nor points at static metadata.
+ */
+bool
+xfs_verify_agbno_ptr(
+	struct xfs_mount	*mp,
+	xfs_agnumber_t		agno,
+	xfs_agblock_t		agbno)
+{
+	xfs_agblock_t		eoag;
+
+	eoag = xfs_ag_block_count(mp, agno);
+	if (agbno >= eoag)
+		return false;
+	if (agbno <= XFS_AGFL_BLOCK(mp))
+		return false;
+	return true;
+}
+
+/*
+ * Verify that an FS block number pointer neither points outside the
+ * filesystem nor points at static AG metadata.
+ */
+bool
+xfs_verify_fsbno_ptr(
+	struct xfs_mount	*mp,
+	xfs_fsblock_t		fsbno)
+{
+	xfs_agnumber_t		agno = XFS_FSB_TO_AGNO(mp, fsbno);
+
+	if (agno >= mp->m_sb.sb_agcount)
+		return false;
+	return xfs_verify_agbno_ptr(mp, agno, XFS_FSB_TO_AGBNO(mp, fsbno));
+}
diff --git a/fs/xfs/libxfs/xfs_alloc.h b/fs/xfs/libxfs/xfs_alloc.h
index ef26edc..3185807 100644
--- a/fs/xfs/libxfs/xfs_alloc.h
+++ b/fs/xfs/libxfs/xfs_alloc.h
@@ -232,5 +232,9 @@ int xfs_alloc_query_range(struct xfs_btree_cur *cur,
 		xfs_alloc_query_range_fn fn, void *priv);
 int xfs_alloc_query_all(struct xfs_btree_cur *cur, xfs_alloc_query_range_fn fn,
 		void *priv);
+xfs_agblock_t xfs_ag_block_count(struct xfs_mount *mp, xfs_agnumber_t agno);
+bool xfs_verify_agbno_ptr(struct xfs_mount *mp, xfs_agnumber_t agno,
+		xfs_agblock_t agbno);
+bool xfs_verify_fsbno_ptr(struct xfs_mount *mp, xfs_fsblock_t fsbno);
 
 #endif	/* __XFS_ALLOC_H__ */
diff --git a/fs/xfs/libxfs/xfs_rtbitmap.c b/fs/xfs/libxfs/xfs_rtbitmap.c
index 5d4e43e..0a49348 100644
--- a/fs/xfs/libxfs/xfs_rtbitmap.c
+++ b/fs/xfs/libxfs/xfs_rtbitmap.c
@@ -1086,3 +1086,15 @@ xfs_rtalloc_query_all(
 
 	return xfs_rtalloc_query_range(tp, &keys[0], &keys[1], fn, priv);
 }
+
+/*
+ * Verify that an realtime block number pointer doesn't point off the
+ * end of the realtime device.
+ */
+bool
+xfs_verify_rtbno_ptr(
+	struct xfs_mount	*mp,
+	xfs_rtblock_t		rtbno)
+{
+	return rtbno < mp->m_sb.sb_rblocks;
+}
diff --git a/fs/xfs/xfs_rtalloc.h b/fs/xfs/xfs_rtalloc.h
index 79defa7..11b8554 100644
--- a/fs/xfs/xfs_rtalloc.h
+++ b/fs/xfs/xfs_rtalloc.h
@@ -138,6 +138,7 @@ int xfs_rtalloc_query_range(struct xfs_trans *tp,
 int xfs_rtalloc_query_all(struct xfs_trans *tp,
 			  xfs_rtalloc_query_range_fn fn,
 			  void *priv);
+bool xfs_verify_rtbno_ptr(struct xfs_mount *mp, xfs_rtblock_t rtbno);
 #else
 # define xfs_rtallocate_extent(t,b,min,max,l,f,p,rb)    (ENOSYS)
 # define xfs_rtfree_extent(t,b,l)                       (ENOSYS)
@@ -146,6 +147,7 @@ int xfs_rtalloc_query_all(struct xfs_trans *tp,
 # define xfs_rtalloc_query_range(t,l,h,f,p)             (ENOSYS)
 # define xfs_rtalloc_query_all(t,f,p)                   (ENOSYS)
 # define xfs_rtbuf_get(m,t,b,i,p)                       (ENOSYS)
+# define xfs_verify_rtbno_ptr(m, r)			(false)
 static inline int		/* error */
 xfs_rtmount_init(
 	xfs_mount_t	*mp)	/* file system mount structure */

