linux: implement filesystem-side copy/clone functions

This implements the Linux VFS ops required to service the file
copy/clone APIs:

  .copy_file_range    (4.5+)
  .clone_file_range   (4.5-4.19)
  .dedupe_file_range  (4.5-4.19)
  .remap_file_range   (4.20+)

Note that dedupe_file_range() and remap_file_range(REMAP_FILE_DEDUP) are
hooked up here, but are not implemented yet.

Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Kay Pedersen <[email protected]>
Signed-off-by: Rob Norris <[email protected]>
Sponsored-By: OpenDrives Inc.
Sponsored-By: Klara Inc.
Closes #15050

3 files changed, 196 insertions, 1 deletions

diff --git a/module/Kbuild.in b/module/Kbuild.in
index 485331ac6..c13217159 100644
--- a/module/Kbuild.in
+++ b/module/Kbuild.in
@@ -461,6 +461,7 @@ ZFS_OBJS_OS := \
 	zpl_ctldir.o \
 	zpl_export.o \
 	zpl_file.o \
+	zpl_file_range.o \
 	zpl_inode.o \
 	zpl_super.o \
 	zpl_xattr.o \
diff --git a/module/os/linux/zfs/zpl_file.c b/module/os/linux/zfs/zpl_file.c
index e690525d3..92b603e98 100644
--- a/module/os/linux/zfs/zpl_file.c
+++ b/module/os/linux/zfs/zpl_file.c
@@ -1283,7 +1283,6 @@ zpl_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 }
 #endif /* CONFIG_COMPAT */
 
-
 const struct address_space_operations zpl_address_space_operations = {
 #ifdef HAVE_VFS_READPAGES
 	.readpages	= zpl_readpages,
@@ -1333,6 +1332,18 @@ const struct file_operations zpl_file_operations = {
 	.aio_fsync	= zpl_aio_fsync,
 #endif
 	.fallocate	= zpl_fallocate,
+#ifdef HAVE_VFS_COPY_FILE_RANGE
+	.copy_file_range	= zpl_copy_file_range,
+#endif
+#ifdef HAVE_VFS_REMAP_FILE_RANGE
+	.remap_file_range	= zpl_remap_file_range,
+#endif
+#ifdef HAVE_VFS_CLONE_FILE_RANGE
+	.clone_file_range	= zpl_clone_file_range,
+#endif
+#ifdef HAVE_VFS_DEDUPE_FILE_RANGE
+	.dedupe_file_range	= zpl_dedupe_file_range,
+#endif
 #ifdef HAVE_FILE_FADVISE
 	.fadvise	= zpl_fadvise,
 #endif
diff --git a/module/os/linux/zfs/zpl_file_range.c b/module/os/linux/zfs/zpl_file_range.c
new file mode 100644
index 000000000..db387a748
--- /dev/null
+++ b/module/os/linux/zfs/zpl_file_range.c
@@ -0,0 +1,183 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or https://opensource.org/licenses/CDDL-1.0.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright (c) 2023, Klara Inc.
+ */
+
+#ifdef CONFIG_COMPAT
+#include <linux/compat.h>
+#endif
+#include <linux/fs.h>
+#include <sys/file.h>
+#include <sys/zfs_znode.h>
+#include <sys/zfs_vnops.h>
+#include <sys/zfeature.h>
+
+/*
+ * Clone part of a file via block cloning.
+ *
+ * Note that we are not required to update file offsets; the kernel will take
+ * care of that depending on how it was called.
+ */
+static ssize_t
+__zpl_clone_file_range(struct file *src_file, loff_t src_off,
+    struct file *dst_file, loff_t dst_off, size_t len)
+{
+	struct inode *src_i = file_inode(src_file);
+	struct inode *dst_i = file_inode(dst_file);
+	uint64_t src_off_o = (uint64_t)src_off;
+	uint64_t dst_off_o = (uint64_t)dst_off;
+	uint64_t len_o = (uint64_t)len;
+	cred_t *cr = CRED();
+	fstrans_cookie_t cookie;
+	int err;
+
+	if (!spa_feature_is_enabled(
+	    dmu_objset_spa(ITOZSB(dst_i)->z_os), SPA_FEATURE_BLOCK_CLONING))
+		return (-EOPNOTSUPP);
+
+	if (src_i != dst_i)
+		spl_inode_lock_shared(src_i);
+	spl_inode_lock(dst_i);
+
+	crhold(cr);
+	cookie = spl_fstrans_mark();
+
+	err = -zfs_clone_range(ITOZ(src_i), &src_off_o, ITOZ(dst_i),
+	    &dst_off_o, &len_o, cr);
+
+	spl_fstrans_unmark(cookie);
+	crfree(cr);
+
+	spl_inode_unlock(dst_i);
+	if (src_i != dst_i)
+		spl_inode_unlock_shared(src_i);
+
+	if (err < 0)
+		return (err);
+
+	return ((ssize_t)len_o);
+}
+
+#ifdef HAVE_VFS_COPY_FILE_RANGE
+/*
+ * Entry point for copy_file_range(). Copy len bytes from src_off in src_file
+ * to dst_off in dst_file. We are permitted to do this however we like, so we
+ * try to just clone the blocks, and if we can't support it, fall back to the
+ * kernel's generic byte copy function.
+ */
+ssize_t
+zpl_copy_file_range(struct file *src_file, loff_t src_off,
+    struct file *dst_file, loff_t dst_off, size_t len, unsigned int flags)
+{
+	ssize_t ret;
+
+	if (flags != 0)
+		return (-EINVAL);
+
+	/* Try to do it via zfs_clone_range() */
+	ret =__zpl_clone_file_range(src_file, src_off,
+	    dst_file, dst_off, len);
+
+#ifdef HAVE_VFS_GENERIC_COPY_FILE_RANGE
+	/*
+	 * Since Linux 5.3 the filesystem driver is responsible for executing
+	 * an appropriate fallback, and a generic fallback function is provided.
+	 */
+	if (ret == -EOPNOTSUPP || ret == -EXDEV)
+		ret = generic_copy_file_range(src_file, src_off, dst_file,
+		    dst_off, len, flags);
+#endif /* HAVE_VFS_GENERIC_COPY_FILE_RANGE */
+
+	return (ret);
+}
+#endif /* HAVE_VFS_COPY_FILE_RANGE */
+
+#ifdef HAVE_VFS_REMAP_FILE_RANGE
+/*
+ * Entry point for FICLONE/FICLONERANGE/FIDEDUPERANGE.
+ *
+ * FICLONE and FICLONERANGE are basically the same as copy_file_range(), except
+ * that they must clone - they cannot fall back to copying. FICLONE is exactly
+ * FICLONERANGE, for the entire file. We don't need to try to tell them apart;
+ * the kernel will sort that out for us.
+ *
+ * FIDEDUPERANGE is for turning a non-clone into a clone, that is, compare the
+ * range in both files and if they're the same, arrange for them to be backed
+ * by the same storage.
+ */
+loff_t
+zpl_remap_file_range(struct file *src_file, loff_t src_off,
+    struct file *dst_file, loff_t dst_off, loff_t len, unsigned int flags)
+{
+	if (flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_CAN_SHORTEN))
+		return (-EINVAL);
+
+	/*
+	 * REMAP_FILE_CAN_SHORTEN lets us know we can clone less than the given
+	 * range if we want. Its designed for filesystems that make data past
+	 * EOF available, and don't want it to be visible in both files. ZFS
+	 * doesn't do that, so we just turn the flag off.
+	 */
+	flags &= ~REMAP_FILE_CAN_SHORTEN;
+
+	if (flags & REMAP_FILE_DEDUP)
+		/* No support for dedup yet */
+		return (-EOPNOTSUPP);
+
+	/* Zero length means to clone everything to the end of the file */
+	if (len == 0)
+		len = i_size_read(file_inode(src_file)) - src_off;
+
+	return (__zpl_clone_file_range(src_file, src_off,
+	    dst_file, dst_off, len));
+}
+#endif /* HAVE_VFS_REMAP_FILE_RANGE */
+
+#ifdef HAVE_VFS_CLONE_FILE_RANGE
+/*
+ * Entry point for FICLONE and FICLONERANGE, before Linux 4.20.
+ */
+int
+zpl_clone_file_range(struct file *src_file, loff_t src_off,
+    struct file *dst_file, loff_t dst_off, uint64_t len)
+{
+	/* Zero length means to clone everything to the end of the file */
+	if (len == 0)
+		len = i_size_read(file_inode(src_file)) - src_off;
+
+	return (__zpl_clone_file_range(src_file, src_off,
+	    dst_file, dst_off, len));
+}
+#endif /* HAVE_VFS_CLONE_FILE_RANGE */
+
+#ifdef HAVE_VFS_DEDUPE_FILE_RANGE
+/*
+ * Entry point for FIDEDUPERANGE, before Linux 4.20.
+ */
+int
+zpl_dedupe_file_range(struct file *src_file, loff_t src_off,
+    struct file *dst_file, loff_t dst_off, uint64_t len)
+{
+	/* No support for dedup yet */
+	return (-EOPNOTSUPP);
+}
+#endif /* HAVE_VFS_DEDUPE_FILE_RANGE */