patch: fs: allow cross VFS mount reflinks

1 files changed, 110 insertions, 0 deletions

diff --git a/fs-allow-cross-vfsmount-reflink-dedupe.patch b/fs-allow-cross-vfsmount-reflink-dedupe.patch
new file mode 100644
index 000000000000..d737180dafe2
--- /dev/null
+++ b/fs-allow-cross-vfsmount-reflink-dedupe.patch
@@ -0,0 +1,110 @@
+From 4caa9af06265aef40239847d14b2182f5dd35a44 Mon Sep 17 00:00:00 2001
+From: Scott B <arglebargle@arglebargle.dev>
+Date: Fri, 18 Feb 2022 16:15:23 -0800
+Subject: [PATCH] fs: allow cross-vfsmount reflink/dedupe
+
+Squashed commit of the following:
+
+commit d053c48ab87a8668d5eb27765b9ff10573053091
+Author: Josef Bacik <josef@toxicpanda.com>
+Date:   Fri Feb 18 09:38:14 2022 -0500
+
+    fs: allow cross-vfsmount reflink/dedupe
+
+    Currently we disallow reflink and dedupe if the two files aren't on the
+    same vfsmount.  However we really only need to disallow it if they're
+    not on the same super block.  It is very common for btrfs to have a main
+    subvolume that is mounted and then different subvolumes mounted at
+    different locations.  It's allowed to reflink between these volumes, but
+    the vfsmount check disallows this.  Instead fix dedupe to check for the
+    same superblock, and simply remove the vfsmount check for reflink as it
+    already does the superblock check.
+
+    Reviewed-by: Darrick J. Wong <djwong@kernel.org>
+    Reviewed-by: Nikolay Borisov <nborisov@suse.com>
+    Reviewed-by: David Sterba <dsterba@suse.com>
+    Signed-off-by: Josef Bacik <josef@toxicpanda.com>
+
+commit 8d92b5b06130d1557e200dd64bb901f94ff661ea
+Author: Josef Bacik <josef@toxicpanda.com>
+Date:   Fri Feb 18 09:38:13 2022 -0500
+
+    btrfs: remove the cross file system checks from remap
+
+    The sb check is already done in do_clone_file_range, and the mnt check
+    (which will hopefully go away in a subsequent patch) is done in
+    ioctl_file_clone().  Remove the check in our code and put an ASSERT() to
+    make sure it doesn't change underneath us.
+
+    Signed-off-by: Josef Bacik <josef@toxicpanda.com>
+---
+ fs/btrfs/reflink.c | 4 +---
+ fs/ioctl.c         | 4 ----
+ fs/remap_range.c   | 7 +------
+ 3 files changed, 2 insertions(+), 13 deletions(-)
+
+diff --git a/fs/btrfs/reflink.c b/fs/btrfs/reflink.c
+index e0f93b357548..5804f4af2629 100644
+--- a/fs/btrfs/reflink.c
++++ b/fs/btrfs/reflink.c
+@@ -772,9 +772,7 @@ static int btrfs_remap_file_range_prep(struct file *file_in, loff_t pos_in,
+ 		if (btrfs_root_readonly(root_out))
+ 			return -EROFS;
+ 
+-		if (file_in->f_path.mnt != file_out->f_path.mnt ||
+-		    inode_in->i_sb != inode_out->i_sb)
+-			return -EXDEV;
++		ASSERT(inode_in->i_sb == inode_out->i_sb);
+ 	}
+ 
+ 	/* Don't make the dst file partly checksummed */
+diff --git a/fs/ioctl.c b/fs/ioctl.c
+index 504e69578112..79550f5f4c45 100644
+--- a/fs/ioctl.c
++++ b/fs/ioctl.c
+@@ -236,9 +236,6 @@ static long ioctl_file_clone(struct file *dst_file, unsigned long srcfd,
+ 
+ 	if (!src_file.file)
+ 		return -EBADF;
+-	ret = -EXDEV;
+-	if (src_file.file->f_path.mnt != dst_file->f_path.mnt)
+-		goto fdput;
+ 	cloned = vfs_clone_file_range(src_file.file, off, dst_file, destoff,
+ 				      olen, 0);
+ 	if (cloned < 0)
+@@ -247,7 +244,6 @@ static long ioctl_file_clone(struct file *dst_file, unsigned long srcfd,
+ 		ret = -EINVAL;
+ 	else
+ 		ret = 0;
+-fdput:
+ 	fdput(src_file);
+ 	return ret;
+ }
+diff --git a/fs/remap_range.c b/fs/remap_range.c
+index 6d4a9beaa097..264ec4541a6c 100644
+--- a/fs/remap_range.c
++++ b/fs/remap_range.c
+@@ -368,11 +368,6 @@ loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
+ 
+ 	WARN_ON_ONCE(remap_flags & REMAP_FILE_DEDUP);
+ 
+-	/*
+-	 * FICLONE/FICLONERANGE ioctls enforce that src and dest files are on
+-	 * the same mount. Practically, they only need to be on the same file
+-	 * system.
+-	 */
+ 	if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
+ 		return -EXDEV;
+ 
+@@ -464,7 +459,7 @@ loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
+ 		goto out_drop_write;
+ 
+ 	ret = -EXDEV;
+-	if (src_file->f_path.mnt != dst_file->f_path.mnt)
++	if (file_inode(src_file)->i_sb != file_inode(dst_file)->i_sb)
+ 		goto out_drop_write;
+ 
+ 	ret = -EISDIR;
+-- 
+2.35.1
+