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Subject[patch 038/100] dm snapshot: refactor __find_pending_exception
-stable review patch.  If anyone has any objections, please let us know.
---------------------

From: Mikulas Patocka <mpatocka@redhat.com>

upstream commit: 2913808eb56a6445a7b277eb8d17651c8defb035

Move looking-up of a pending exception from __find_pending_exception to another
function.

Cc: stable@kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---
drivers/md/dm-snap.c | 52 +++++++++++++++++++++++++++------------------------
1 file changed, 28 insertions(+), 24 deletions(-)

--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -972,6 +972,17 @@ static void start_copy(struct dm_snap_pe
&src, 1, &dest, 0, copy_callback, pe);
}

+static struct dm_snap_pending_exception *
+__lookup_pending_exception(struct dm_snapshot *s, chunk_t chunk)
+{
+ struct dm_snap_exception *e = lookup_exception(&s->pending, chunk);
+
+ if (!e)
+ return NULL;
+
+ return container_of(e, struct dm_snap_pending_exception, e);
+}
+
/*
* Looks to see if this snapshot already has a pending exception
* for this chunk, otherwise it allocates a new one and inserts
@@ -983,21 +994,10 @@ static void start_copy(struct dm_snap_pe
static struct dm_snap_pending_exception *
__find_pending_exception(struct dm_snapshot *s, struct bio *bio)
{
- struct dm_snap_exception *e;
- struct dm_snap_pending_exception *pe;
+ struct dm_snap_pending_exception *pe, *pe2;
chunk_t chunk = sector_to_chunk(s, bio->bi_sector);

/*
- * Is there a pending exception for this already ?
- */
- e = lookup_exception(&s->pending, chunk);
- if (e) {
- /* cast the exception to a pending exception */
- pe = container_of(e, struct dm_snap_pending_exception, e);
- goto out;
- }
-
- /*
* Create a new pending exception, we don't want
* to hold the lock while we do this.
*/
@@ -1010,11 +1010,10 @@ __find_pending_exception(struct dm_snaps
return NULL;
}

- e = lookup_exception(&s->pending, chunk);
- if (e) {
+ pe2 = __lookup_pending_exception(s, chunk);
+ if (pe2) {
free_pending_exception(pe);
- pe = container_of(e, struct dm_snap_pending_exception, e);
- goto out;
+ return pe2;
}

pe->e.old_chunk = chunk;
@@ -1032,7 +1031,6 @@ __find_pending_exception(struct dm_snaps
get_pending_exception(pe);
insert_exception(&s->pending, &pe->e);

- out:
return pe;
}

@@ -1083,11 +1081,14 @@ static int snapshot_map(struct dm_target
* writeable.
*/
if (bio_rw(bio) == WRITE) {
- pe = __find_pending_exception(s, bio);
+ pe = __lookup_pending_exception(s, chunk);
if (!pe) {
- __invalidate_snapshot(s, -ENOMEM);
- r = -EIO;
- goto out_unlock;
+ pe = __find_pending_exception(s, bio);
+ if (!pe) {
+ __invalidate_snapshot(s, -ENOMEM);
+ r = -EIO;
+ goto out_unlock;
+ }
}

remap_exception(s, &pe->e, bio, chunk);
@@ -1217,10 +1218,13 @@ static int __origin_write(struct list_he
if (e)
goto next_snapshot;

- pe = __find_pending_exception(snap, bio);
+ pe = __lookup_pending_exception(snap, chunk);
if (!pe) {
- __invalidate_snapshot(snap, -ENOMEM);
- goto next_snapshot;
+ pe = __find_pending_exception(snap, bio);
+ if (!pe) {
+ __invalidate_snapshot(snap, -ENOMEM);
+ goto next_snapshot;
+ }
}

if (!primary_pe) {


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