diff options
| author | Kiyoshi Ueda <k-ueda@ct.jp.nec.com> | 2006-12-08 13:41:05 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.osdl.org> | 2006-12-08 19:29:09 +0300 |
| commit | 45cbcd798354251b99694086af9d57c99e89bb43 (patch) | |
| tree | a9822364a37993b72ffecf356aa040e8fefe6cb5 /drivers/md | |
| parent | a3d77d35be6f416a250c528c3ed5c70013a915e8 (diff) | |
| download | linux-45cbcd798354251b99694086af9d57c99e89bb43.tar.xz | |
[PATCH] dm: map and endio return code clarification
Tighten the use of return values from the target map and end_io functions.
Values of 2 and above are now explictly reserved for future use. There are no
existing targets using such values.
The patch has no effect on existing behaviour.
o Reserve return values of 2 and above from target map functions.
Any positive value currently indicates "mapping complete", but all
existing drivers use the value 1. We now make that a requirement
so we can assign new meaning to higher values in future.
The new definition of return values from target map functions is:
< 0 : error
= 0 : The target will handle the io (DM_MAPIO_SUBMITTED).
= 1 : Mapping completed (DM_MAPIO_REMAPPED).
> 1 : Reserved (undefined). Previously this was the same as '= 1'.
o Reserve return values of 2 and above from target end_io functions
for similar reasons.
DM_ENDIO_INCOMPLETE is introduced for a return value of 1.
Test results:
I have tested by using the multipath target.
I/Os succeed when valid paths exist.
I/Os are queued in the multipath target when there are no valid paths and
queue_if_no_path is set.
I/Os fail when there are no valid paths and queue_if_no_path is not set.
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: dm-devel@redhat.com
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/dm.c | 13 | ||||
| -rw-r--r-- | drivers/md/dm.h | 11 |
2 files changed, 21 insertions, 3 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c index b42e71bb9e67..d8544e1a4c1f 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -482,9 +482,13 @@ static int clone_endio(struct bio *bio, unsigned int done, int error) r = endio(tio->ti, bio, error, &tio->info); if (r < 0) error = r; - else if (r > 0) - /* the target wants another shot at the io */ + else if (r == DM_ENDIO_INCOMPLETE) + /* The target will handle the io */ return 1; + else if (r) { + DMWARN("unimplemented target endio return value: %d", r); + BUG(); + } } dec_pending(tio->io, error); @@ -542,7 +546,7 @@ static void __map_bio(struct dm_target *ti, struct bio *clone, atomic_inc(&tio->io->io_count); sector = clone->bi_sector; r = ti->type->map(ti, clone, &tio->info); - if (r > 0) { + if (r == DM_MAPIO_REMAPPED) { /* the bio has been remapped so dispatch it */ blk_add_trace_remap(bdev_get_queue(clone->bi_bdev), clone, @@ -560,6 +564,9 @@ static void __map_bio(struct dm_target *ti, struct bio *clone, clone->bi_private = md->bs; bio_put(clone); free_tio(md, tio); + } else if (r) { + DMWARN("unimplemented target map return value: %d", r); + BUG(); } } diff --git a/drivers/md/dm.h b/drivers/md/dm.h index 81c98d6e35e9..293d5ce62a21 100644 --- a/drivers/md/dm.h +++ b/drivers/md/dm.h @@ -33,6 +33,17 @@ #define SECTOR_SHIFT 9 /* + * Definitions of return values from target end_io function. + */ +#define DM_ENDIO_INCOMPLETE 1 + +/* + * Definitions of return values from target map function. + */ +#define DM_MAPIO_SUBMITTED 0 +#define DM_MAPIO_REMAPPED 1 + +/* * Suspend feature flags */ #define DM_SUSPEND_LOCKFS_FLAG (1 << 0) |