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>

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 986283c5332f95ddcc70dea159ebe965ca33e29a..44e1aa30e3f66b19300b3689cd7d74679e3c06cc 100644 (file)
--- 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)