ide-cd: use scatterlists for PIO transfers (fs requests)

* Export ide_pio_bytes().

* Add ->last_xfer_len field to struct ide_cmd.

* Add ide_cd_error_cmd() helper to ide-cd.

* Convert ide-cd to use scatterlists also for PIO transfers (fs requests
  only for now) and get rid of partial completions (except when the error
  happens -- which is still subject to change later because looking at
  ATAPI spec it seems that the device is free to error the whole transfer
  with setting the Error bit only on the last transfer chunk).

* Update ide_cd_{prepare_rw,restore_request,do_request}() accordingly.

* Inline ide_cd_restore_request() into cdrom_start_rw().

Cc: Borislav Petkov <petkovbb@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/ide.h b/include/linux/ide.h
index d5d832271f44..c2841c0c36c8 100644
--- a/include/linux/ide.h
+++ b/include/linux/ide.h
@@ -352,6 +352,8 @@ struct ide_cmd {
 
         unsigned int            nbytes;
         unsigned int            nleft;
+        unsigned int            last_xfer_len;
+
         struct scatterlist      *cursg;
         unsigned int            cursg_ofs;
 
@@ -1226,6 +1228,8 @@ ide_startstop_t ide_issue_pc(ide_drive_t *, struct ide_cmd *);
 
 ide_startstop_t do_rw_taskfile(ide_drive_t *, struct ide_cmd *);
 
+void ide_pio_bytes(ide_drive_t *, struct ide_cmd *, unsigned int, unsigned int);
+
 void ide_finish_cmd(ide_drive_t *, struct ide_cmd *, u8);
 
 int ide_raw_taskfile(ide_drive_t *, struct ide_cmd *, u8 *, u16);