xfs: Conditionally upgrade existing inodes to use large extent counters

Source kernel commit: 4f86bb4b66c999ad9ddcfd49fec93992eeba2715

This commit enables upgrading existing inodes to use large extent counters
provided that underlying filesystem's superblock has large extent counter
feature enabled.

Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Chandan Babu R <chandan.babu@oracle.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>

5 files changed, 44 insertions, 2 deletions

diff --git a/libxfs/xfs_attr.c b/libxfs/xfs_attr.c
index 9a9da4594d..f08918024c 100644
--- a/libxfs/xfs_attr.c
+++ b/libxfs/xfs_attr.c
@@ -776,6 +776,9 @@ xfs_attr_set(
 	if (args->value || xfs_inode_hasattr(dp)) {
 		error = xfs_iext_count_may_overflow(dp, XFS_ATTR_FORK,
 				XFS_IEXT_ATTR_MANIP_CNT(rmt_blks));
+		if (error == -EFBIG)
+			error = xfs_iext_count_upgrade(args->trans, dp,
+					XFS_IEXT_ATTR_MANIP_CNT(rmt_blks));
 		if (error)
 			goto out_trans_cancel;
 	}
diff --git a/libxfs/xfs_bmap.c b/libxfs/xfs_bmap.c
index 591d79c403..7930924608 100644
--- a/libxfs/xfs_bmap.c
+++ b/libxfs/xfs_bmap.c
@@ -4517,14 +4517,16 @@ xfs_bmapi_convert_delalloc(
 		return error;
 
 	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	xfs_trans_ijoin(tp, ip, 0);
 
 	error = xfs_iext_count_may_overflow(ip, whichfork,
 			XFS_IEXT_ADD_NOSPLIT_CNT);
+	if (error == -EFBIG)
+		error = xfs_iext_count_upgrade(tp, ip,
+				XFS_IEXT_ADD_NOSPLIT_CNT);
 	if (error)
 		goto out_trans_cancel;
 
-	xfs_trans_ijoin(tp, ip, 0);
-
 	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &bma.icur, &bma.got) ||
 	    bma.got.br_startoff > offset_fsb) {
 		/*
diff --git a/libxfs/xfs_format.h b/libxfs/xfs_format.h
index 43de892d03..3beaa819b7 100644
--- a/libxfs/xfs_format.h
+++ b/libxfs/xfs_format.h
@@ -935,6 +935,17 @@ enum xfs_dinode_fmt {
 #define XFS_MAX_EXTCNT_ATTR_FORK_SMALL	((xfs_extnum_t)((1ULL << 15) - 1))
 
 /*
+ * When we upgrade an inode to the large extent counts, the maximum value by
+ * which the extent count can increase is bound by the change in size of the
+ * on-disk field. No upgrade operation should ever be adding more than a few
+ * tens of extents, so if we get a really large value it is a sign of a code bug
+ * or corruption.
+ */
+#define XFS_MAX_EXTCNT_UPGRADE_NR	\
+	min(XFS_MAX_EXTCNT_ATTR_FORK_LARGE - XFS_MAX_EXTCNT_ATTR_FORK_SMALL,	\
+	    XFS_MAX_EXTCNT_DATA_FORK_LARGE - XFS_MAX_EXTCNT_DATA_FORK_SMALL)
+
+/*
  * Inode minimum and maximum sizes.
  */
 #define	XFS_DINODE_MIN_LOG	8
diff --git a/libxfs/xfs_inode_fork.c b/libxfs/xfs_inode_fork.c
index 568c0ff4e5..da59232918 100644
--- a/libxfs/xfs_inode_fork.c
+++ b/libxfs/xfs_inode_fork.c
@@ -754,3 +754,27 @@ xfs_iext_count_may_overflow(
 
 	return 0;
 }
+
+/*
+ * Upgrade this inode's extent counter fields to be able to handle a potential
+ * increase in the extent count by nr_to_add.  Normally this is the same
+ * quantity that caused xfs_iext_count_may_overflow() to return -EFBIG.
+ */
+int
+xfs_iext_count_upgrade(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*ip,
+	uint			nr_to_add)
+{
+	ASSERT(nr_to_add <= XFS_MAX_EXTCNT_UPGRADE_NR);
+
+	if (!xfs_has_large_extent_counts(ip->i_mount) ||
+	    xfs_inode_has_large_extent_counts(ip) ||
+	    XFS_TEST_ERROR(false, ip->i_mount, XFS_ERRTAG_REDUCE_MAX_IEXTENTS))
+		return -EFBIG;
+
+	ip->i_diflags2 |= XFS_DIFLAG2_NREXT64;
+	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+
+	return 0;
+}
diff --git a/libxfs/xfs_inode_fork.h b/libxfs/xfs_inode_fork.h
index 6f9d69f889..4f68c1f20b 100644
--- a/libxfs/xfs_inode_fork.h
+++ b/libxfs/xfs_inode_fork.h
@@ -275,6 +275,8 @@ int xfs_ifork_verify_local_data(struct xfs_inode *ip);
 int xfs_ifork_verify_local_attr(struct xfs_inode *ip);
 int xfs_iext_count_may_overflow(struct xfs_inode *ip, int whichfork,
 		int nr_to_add);
+int xfs_iext_count_upgrade(struct xfs_trans *tp, struct xfs_inode *ip,
+		uint nr_to_add);
 
 /* returns true if the fork has extents but they are not read in yet. */
 static inline bool xfs_need_iread_extents(struct xfs_ifork *ifp)