dm crypt: tidy io ref counting

Make io reference counting more obvious.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 8 insertions, 12 deletions

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 986283c5332f..44e1aa30e3f6 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -584,7 +584,6 @@ static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io, int error)
                 crypt_free_buffer_pages(cc, clone);
                 bio_put(clone);
                 io->error = -EIO;
-                crypt_dec_pending(io);
                 return;
         }
 
@@ -593,6 +592,9 @@ static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io, int error)
 
         clone->bi_sector = cc->start + io->sector;
         io->sector += bio_sectors(clone);
+
+        atomic_inc(&io->pending);
+        generic_make_request(clone);
 }
 
 static void kcryptd_crypt_write_convert_loop(struct dm_crypt_io *io)
@@ -610,7 +612,6 @@ static void kcryptd_crypt_write_convert_loop(struct dm_crypt_io *io)
                 clone = crypt_alloc_buffer(io, remaining);
                 if (unlikely(!clone)) {
                         io->error = -ENOMEM;
-                        crypt_dec_pending(io);
                         return;
                 }
 
@@ -625,16 +626,6 @@ static void kcryptd_crypt_write_convert_loop(struct dm_crypt_io *io)
                 if (unlikely(r < 0))
                         return;
 
-                /* Grab another reference to the io struct
-                 * before we kick off the request */
-                if (remaining)
-                        atomic_inc(&io->pending);
-
-                generic_make_request(clone);
-
-                /* Do not reference clone after this - it
-                 * may be gone already. */
-
                 /* out of memory -> run queues */
                 if (unlikely(remaining))
                         congestion_wait(WRITE, HZ/100);
@@ -645,10 +636,15 @@ static void kcryptd_crypt_write_convert(struct dm_crypt_io *io)
 {
         struct crypt_config *cc = io->target->private;
 
+        /*
+         * Prevent io from disappearing until this function completes.
+         */
         atomic_inc(&io->pending);
 
         crypt_convert_init(cc, &io->ctx, NULL, io->base_bio, io->sector);
         kcryptd_crypt_write_convert_loop(io);
+
+        crypt_dec_pending(io);
 }
 
 static void kcryptd_crypt_read_done(struct dm_crypt_io *io, int error)