On Mon, May 20, 2024 at 03:50:18PM +0530, Nitesh Shetty wrote:
> From: Anuj Gupta <anuj20.g@xxxxxxxxxxx>
>
> This is a prep patch. Allow copy_file_range to work for block devices.
> Relaxing generic_copy_file_checks allows us to reuse the existing infra,
> instead of adding a new user interface for block copy offload.
> Change generic_copy_file_checks to use ->f_mapping->host for both inode_in
> and inode_out. Allow block device in generic_file_rw_checks.
>
> Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
> Signed-off-by: Anuj Gupta <anuj20.g@xxxxxxxxxxx>
> Signed-off-by: Nitesh Shetty <nj.shetty@xxxxxxxxxxx>
> ---
> fs/read_write.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/fs/read_write.c b/fs/read_write.c
> index ef6339391351..31645ca5ed58 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -1413,8 +1413,8 @@ static int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
> struct file *file_out, loff_t pos_out,
> size_t *req_count, unsigned int flags)
> {
> - struct inode *inode_in = file_inode(file_in);
> - struct inode *inode_out = file_inode(file_out);
> + struct inode *inode_in = file_in->f_mapping->host;
> + struct inode *inode_out = file_out->f_mapping->host;
> uint64_t count = *req_count;
> loff_t size_in;
> int ret;
Ok, so this changes from file->f_inode to file->mapping->host. No
doubt this is because of how bdev inode mappings are munged.
However, the first code that is run here is:
ret = generic_file_rw_checks(file_in, file_out);
and that function still uses file_inode().
Hence there checks:
> @@ -1726,7 +1726,9 @@ int generic_file_rw_checks(struct file *file_in, struct file *file_out)
> /* Don't copy dirs, pipes, sockets... */
> if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
> return -EISDIR;
> - if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
> + if (!S_ISREG(inode_in->i_mode) && !S_ISBLK(inode_in->i_mode))
> + return -EINVAL;
> + if ((inode_in->i_mode & S_IFMT) != (inode_out->i_mode & S_IFMT))
> return -EINVAL;
.... are being done on different inodes to the rest of
generic_copy_file_checks() when block devices are used.
Is this correct? If so, this needs a pair of comments (one for each
function) to explain why the specific inode used for these functions
is correct for block devices....
-Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
