diff --git a/Documentation/admin-guide/xfs.rst b/Documentation/admin-guide/xfs.rst
index f461d6c33534..a0e271dcaf82 100644
--- a/Documentation/admin-guide/xfs.rst
+++ b/Documentation/admin-guide/xfs.rst
@@ -210,6 +210,28 @@ When mounting an XFS filesystem, the following options are accepted.
 	inconsistent namespace presentation during or after a
 	failover event.
 
+Deprecation of V4 Format
+========================
+
+The V4 filesystem format lacks certain features that are supported by
+the V5 format, such as metadata checksumming, strengthened metadata
+verification, and the ability to store timestamps past the year 2038.
+Because of this, the V4 format is deprecated.  All users should upgrade
+by backing up their files, reformatting, and restoring from the backup.
+
+Administrators and users can detect a V4 filesystem by running xfs_info
+against a filesystem mountpoint and checking for a string containing
+"crc=".  If no such string is found, please upgrade xfsprogs to the
+latest version and try again.
+
+The deprecation will take place in two parts.  Support for mounting V4
+filesystems can now be disabled at kernel build time via Kconfig option.
+The option will default to yes until September 2025, at which time it
+will be changed to default to no.  In September 2030, support will be
+removed from the codebase entirely.
+
+Note: Distributors may choose to withdraw V4 format support earlier than
+the dates listed above.
 
 Deprecated Mount Options
 ========================
@@ -217,6 +239,7 @@ Deprecated Mount Options
 ===========================     ================
   Name				Removal Schedule
 ===========================     ================
+Mounting with V4 filesystem     September 2030
 ===========================     ================
 
 
diff --git a/fs/xfs/Kconfig b/fs/xfs/Kconfig
index e685299eb3d2..5422227e9e93 100644
--- a/fs/xfs/Kconfig
+++ b/fs/xfs/Kconfig
@@ -22,6 +22,30 @@ config XFS_FS
 	  system of your root partition is compiled as a module, you'll need
 	  to use an initial ramdisk (initrd) to boot.
 
+config XFS_SUPPORT_V4
+	bool "Support deprecated V4 (crc=0) format"
+	default y
+	help
+	  The V4 filesystem format lacks certain features that are supported
+	  by the V5 format, such as metadata checksumming, strengthened
+	  metadata verification, and the ability to store timestamps past the
+	  year 2038.  Because of this, the V4 format is deprecated.  All users
+	  should upgrade by backing up their files, reformatting, and restoring
+	  from the backup.
+
+	  Administrators and users can detect a V4 filesystem by running
+	  xfs_info against a filesystem mountpoint and checking for a string
+	  beginning with "crc=".  If the string "crc=0" is found, the
+	  filesystem is a V4 filesystem.  If no such string is found, please
+	  upgrade xfsprogs to the latest version and try again.
+
+	  This option will become default N in September 2025.  Support for the
+	  V4 format will be removed entirely in September 2030.  Distributors
+	  can say N here to withdraw support earlier.
+
+	  To continue supporting the old V4 format (crc=0), say Y.
+	  To close off an attack surface, say N.
+
 config XFS_QUOTA
 	bool "XFS Quota support"
 	depends on XFS_FS
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index baf5de30eebb..bb1d079b690d 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1450,6 +1450,19 @@ xfs_fc_fill_super(
 	if (error)
 		goto out_free_sb;
 
+	/* V4 support is undergoing deprecation. */
+	if (!xfs_sb_version_hascrc(&mp->m_sb)) {
+#ifdef CONFIG_XFS_SUPPORT_V4
+		xfs_warn_once(mp,
+	"Deprecated V4 format (crc=0) will not be supported after September 2030.");
+#else
+		xfs_warn(mp,
+	"Deprecated V4 format (crc=0) not supported by kernel.");
+		error = -EINVAL;
+		goto out_free_sb;
+#endif
+	}
+
 	/*
 	 * XFS block mappings use 54 bits to store the logical block offset.
 	 * This should suffice to handle the maximum file size that the VFS