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authorDave Chinner <dchinner@redhat.com>2019-06-05 08:04:47 -0700
committerDarrick J. Wong <darrick.wong@oracle.com>2019-06-09 10:06:18 -0700
commitf16acc9d9b3761ae5e45219c9302f99e20919829 (patch)
treef209a6f178bd32ace2e72c47f2c575f9c6b8fdee /fs/read_write.c
parentLinux 5.2-rc4 (diff)
downloadlinux-dev-f16acc9d9b3761ae5e45219c9302f99e20919829.tar.xz
linux-dev-f16acc9d9b3761ae5e45219c9302f99e20919829.zip
vfs: introduce generic_copy_file_range()
Right now if vfs_copy_file_range() does not use any offload mechanism, it falls back to calling do_splice_direct(). This fails to do basic sanity checks on the files being copied. Before we start adding this necessarily functionality to the fallback path, separate it out into generic_copy_file_range(). generic_copy_file_range() has the same prototype as ->copy_file_range() so that filesystems can use it in their custom ->copy_file_range() method if they so choose. Signed-off-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Amir Goldstein <amir73il@gmail.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Diffstat (limited to 'fs/read_write.c')
-rw-r--r--fs/read_write.c35
1 files changed, 32 insertions, 3 deletions
diff --git a/fs/read_write.c b/fs/read_write.c
index c543d965e288..676b02fae589 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1565,6 +1565,36 @@ COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd,
}
#endif
+/**
+ * generic_copy_file_range - copy data between two files
+ * @file_in: file structure to read from
+ * @pos_in: file offset to read from
+ * @file_out: file structure to write data to
+ * @pos_out: file offset to write data to
+ * @len: amount of data to copy
+ * @flags: copy flags
+ *
+ * This is a generic filesystem helper to copy data from one file to another.
+ * It has no constraints on the source or destination file owners - the files
+ * can belong to different superblocks and different filesystem types. Short
+ * copies are allowed.
+ *
+ * This should be called from the @file_out filesystem, as per the
+ * ->copy_file_range() method.
+ *
+ * Returns the number of bytes copied or a negative error indicating the
+ * failure.
+ */
+
+ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in,
+ struct file *file_out, loff_t pos_out,
+ size_t len, unsigned int flags)
+{
+ return do_splice_direct(file_in, &pos_in, file_out, &pos_out,
+ len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0);
+}
+EXPORT_SYMBOL(generic_copy_file_range);
+
/*
* copy_file_range() differs from regular file read and write in that it
* specifically allows return partial success. When it does so is up to
@@ -1632,9 +1662,8 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
goto done;
}
- ret = do_splice_direct(file_in, &pos_in, file_out, &pos_out,
- len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0);
-
+ ret = generic_copy_file_range(file_in, pos_in, file_out, pos_out, len,
+ flags);
done:
if (ret > 0) {
fsnotify_access(file_in);