xfs: Conditionally upgrade existing inodes to use large extent counters

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>

5 files changed, 44 insertions, 2 deletions

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index 23523b802539..2815cfbbae70 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/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/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 4fab0c92ab70..82d5467ddf2c 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -4524,14 +4524,16 @@ 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/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index 43de892d0305..3beaa819b790 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/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/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index bb5d841aac58..9aee4a1e2fe9 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -756,3 +756,27 @@ 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/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
index 6f9d69f8896e..4f68c1f20beb 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/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)