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From:   David Howells <dhowells@redhat.com>
To:     Jens Axboe <axboe@kernel.dk>, Al Viro <viro@zeniv.linux.org.uk>,
        Christoph Hellwig <hch@infradead.org>
Cc:     David Howells <dhowells@redhat.com>,
        Matthew Wilcox <willy@infradead.org>, Jan Kara <jack@suse.cz>,
        Jeff Layton <jlayton@kernel.org>,
        David Hildenbrand <david@redhat.com>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Logan Gunthorpe <logang@deltatee.com>,
        Hillf Danton <hdanton@sina.com>,
        Christian Brauner <brauner@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Christoph Hellwig <hch@lst.de>,
        Konstantin Komarov <almaz.alexandrovich@paragon-software.com>,
        ntfs3@lists.linux.dev
Subject: [PATCH v22 21/31] ntfs3: Provide a splice-read wrapper
Date:   Mon, 22 May 2023 14:50:08 +0100
Message-Id: <20230522135018.2742245-22-dhowells@redhat.com>
In-Reply-To: <20230522135018.2742245-1-dhowells@redhat.com>
References: <20230522135018.2742245-1-dhowells@redhat.com>
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Provide a splice_read wrapper for NTFS3 to perform various checks before
allowing the operation to proceed.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Christoph Hellwig <hch@lst.de>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: Jens Axboe <axboe@kernel.dk>
cc: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
cc: ntfs3@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
cc: linux-block@vger.kernel.org
cc: linux-mm@kvack.org
---
 fs/ntfs3/file.c | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

diff --git a/fs/ntfs3/file.c b/fs/ntfs3/file.c
index 9a3d55c367d9..667c9dc68b58 100644
--- a/fs/ntfs3/file.c
+++ b/fs/ntfs3/file.c
@@ -744,6 +744,35 @@ static ssize_t ntfs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 	return generic_file_read_iter(iocb, iter);
 }
 
+static ssize_t ntfs_file_splice_read(struct file *in, loff_t *ppos,
+				     struct pipe_inode_info *pipe,
+				     size_t len, unsigned int flags)
+{
+	struct inode *inode = in->f_mapping->host;
+	struct ntfs_inode *ni = ntfs_i(inode);
+
+	if (is_encrypted(ni)) {
+		ntfs_inode_warn(inode, "encrypted i/o not supported");
+		return -EOPNOTSUPP;
+	}
+
+#ifndef CONFIG_NTFS3_LZX_XPRESS
+	if (ni->ni_flags & NI_FLAG_COMPRESSED_MASK) {
+		ntfs_inode_warn(
+			inode,
+			"activate CONFIG_NTFS3_LZX_XPRESS to read external compressed files");
+		return -EOPNOTSUPP;
+	}
+#endif
+
+	if (is_dedup(ni)) {
+		ntfs_inode_warn(inode, "read deduplicated not supported");
+		return -EOPNOTSUPP;
+	}
+
+	return generic_file_splice_read(in, ppos, pipe, len, flags);
+}
+
 /*
  * ntfs_get_frame_pages
  *
@@ -1159,7 +1188,7 @@ const struct file_operations ntfs_file_operations = {
 #ifdef CONFIG_COMPAT
 	.compat_ioctl	= ntfs_compat_ioctl,
 #endif
-	.splice_read	= generic_file_splice_read,
+	.splice_read	= ntfs_file_splice_read,
 	.mmap		= ntfs_file_mmap,
 	.open		= ntfs_file_open,
 	.fsync		= generic_file_fsync,