Al,
Do you have plans merging this patch? I have addressed the comments
from Jeff Layton.
Thank you.
On Thu, Jul 6, 2017 at 4:58 PM, Olga Kornievskaia <aglo@xxxxxxxxx> wrote:
> Hi folks,
>
> Are there any more comments? Will this be accepted?
>
> On Fri, Jun 30, 2017 at 4:58 PM, Olga Kornievskaia <kolga@xxxxxxxxxx> wrote:
>> Allow copy_file_range to copy between different superblocks but only
>> of the same file system types.
>>
>> This feature is needed by NFSv4.2 to perform file copy operation on
>> the same server or file copy between different NFSv4.2 servers.
>>
>> If a file system's fileoperations copy_file_range operation prohibits
>> cross-device copies, fall back to do_splice_direct. This would be
>> needed for the NFS (destination) server side implementation of the
>> file copy and currently for CIFS.
>>
>> Besides NFS, there is only 1 implementor of the copy_file_range FS
>> operation -- CIFS. CIFS assumes incoming file descriptors are both
>> CIFS but it will check if they are coming from different servers and
>> return error code to fall back to do_splice_direct.
>>
>> NFS will allow for copies between different NFS servers.
>>
>> Adding to the vfs.txt documentation to explicitly warn about allowing
>> for different superblocks of the same file type to be passed into the
>> copy_file_range for the future users of copy_file_range method.
>>
>> Signed-off-by: Olga Kornievskaia <kolga@xxxxxxxxxx>
>> ---
>> Documentation/filesystems/vfs.txt | 7 +++++++
>> fs/read_write.c | 13 ++++++-------
>> 2 files changed, 13 insertions(+), 7 deletions(-)
>>
>> diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
>> index f42b906..0c243f6 100644
>> --- a/Documentation/filesystems/vfs.txt
>> +++ b/Documentation/filesystems/vfs.txt
>> @@ -845,6 +845,8 @@ struct file_operations {
>> #ifndef CONFIG_MMU
>> unsigned (*mmap_capabilities)(struct file *);
>> #endif
>> + ssize_t (*copy_file_range)(struct file *, loff_t, struct file *,
>> + loff_t, size_t, unsigned int);
>> };
>>
>> Again, all methods are called without any locks being held, unless
>> @@ -913,6 +915,11 @@ otherwise noted.
>>
>> fallocate: called by the VFS to preallocate blocks or punch a hole.
>>
>> + copy_file_range: called by copy_file_range(2) system call. This method
>> + works on two file descriptors that might reside on
>> + different superblocks of the same type of file system.
>> +
>> +
>> Note that the file operations are implemented by the specific
>> filesystem in which the inode resides. When opening a device node
>> (character or block special) most filesystems will call special
>> diff --git a/fs/read_write.c b/fs/read_write.c
>> index 47c1d44..f981d49 100644
>> --- a/fs/read_write.c
>> +++ b/fs/read_write.c
>> @@ -1589,10 +1589,6 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
>> (file_out->f_flags & O_APPEND))
>> return -EBADF;
>>
>> - /* this could be relaxed once a method supports cross-fs copies */
>> - if (inode_in->i_sb != inode_out->i_sb)
>> - return -EXDEV;
>> -
>> if (len == 0)
>> return 0;
>>
>> @@ -1602,7 +1598,8 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
>> * Try cloning first, this is supported by more file systems, and
>> * more efficient if both clone and copy are supported (e.g. NFS).
>> */
>> - if (file_in->f_op->clone_file_range) {
>> + if (inode_in->i_sb == inode_out->i_sb &&
>> + file_in->f_op->clone_file_range) {
>> ret = file_in->f_op->clone_file_range(file_in, pos_in,
>> file_out, pos_out, len);
>> if (ret == 0) {
>> @@ -1611,10 +1608,12 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
>> }
>> }
>>
>> - if (file_out->f_op->copy_file_range) {
>> + if (file_out->f_op->copy_file_range &&
>> + (file_in->f_op->copy_file_range ==
>> + file_out->f_op->copy_file_range)) {
>> ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out,
>> pos_out, len, flags);
>> - if (ret != -EOPNOTSUPP)
>> + if (ret != -EOPNOTSUPP && ret != -EXDEV)
>> goto done;
>> }
>>
>> --
>> 1.8.3.1
>>
>> --
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