dm io: prepare for new interface

Introduce struct dm_io_client to prepare for per-client mempools and bio_sets.

Temporary functions bios() and io_pool() choose between the per-client
structures and the global ones so the old and new interfaces can co-exist.

Make error_bits optional.

Signed-off-by: Heinz Mauelshagen <hjm@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: Milan Broz <mbroz@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 44 insertions, 17 deletions

diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index 4d19c45158b4..66db79208c1d 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2003 Sistina Software
+ * Copyright (C) 2006 Red Hat GmbH
  *
  * This file is released under the GPL.
  */
@@ -14,11 +15,17 @@
 
 static struct bio_set *_bios;
 
+struct dm_io_client {
+        mempool_t *pool;
+        struct bio_set *bios;
+};
+
 /* FIXME: can we shrink this ? */
 struct io {
         unsigned long error;
         atomic_t count;
         struct task_struct *sleeper;
+        struct dm_io_client *client;
         io_notify_fn callback;
         void *context;
 };
@@ -26,12 +33,24 @@ struct io {
 /*
  * io contexts are only dynamically allocated for asynchronous
  * io.  Since async io is likely to be the majority of io we'll
- * have the same number of io contexts as buffer heads ! (FIXME:
- * must reduce this).
+ * have the same number of io contexts as bios! (FIXME: must reduce this).
  */
 static unsigned _num_ios;
 static mempool_t *_io_pool;
 
+/*
+ * Temporary functions to allow old and new interfaces to co-exist.
+ */
+static struct bio_set *bios(struct dm_io_client *client)
+{
+        return client ? client->bios : _bios;
+}
+
+static mempool_t *io_pool(struct dm_io_client *client)
+{
+        return client ? client->pool : _io_pool;
+}
+
 static unsigned int pages_to_ios(unsigned int pages)
 {
         return 4 * pages;       /* too many ? */
@@ -118,7 +137,7 @@ static void dec_count(struct io *io, unsigned int region, int error)
                         io_notify_fn fn = io->callback;
                         void *context = io->context;
 
-                        mempool_free(io, _io_pool);
+                        mempool_free(io, io_pool(io->client));
                         fn(r, context);
                 }
         }
@@ -241,7 +260,9 @@ static void vm_dp_init(struct dpages *dp, void *data)
 
 static void dm_bio_destructor(struct bio *bio)
 {
-        bio_free(bio, _bios);
+        struct io *io = bio->bi_private;
+
+        bio_free(bio, bios(io->client));
 }
 
 /*-----------------------------------------------------------------
@@ -264,7 +285,7 @@ static void do_region(int rw, unsigned int region, struct io_region *where,
                  * to hide it from bio_add_page().
                  */
                 num_bvecs = (remaining / (PAGE_SIZE >> SECTOR_SHIFT)) + 2;
-                bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, _bios);
+                bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, bios(io->client));
                 bio->bi_sector = where->sector + (where->count - remaining);
                 bio->bi_bdev = where->bdev;
                 bio->bi_end_io = endio;
@@ -319,8 +340,9 @@ static void dispatch_io(int rw, unsigned int num_regions,
         dec_count(io, 0, 0);
 }
 
-static int sync_io(unsigned int num_regions, struct io_region *where,
-            int rw, struct dpages *dp, unsigned long *error_bits)
+static int sync_io(struct dm_io_client *client, unsigned int num_regions,
+                   struct io_region *where, int rw, struct dpages *dp,
+                   unsigned long *error_bits)
 {
         struct io io;
 
@@ -332,6 +354,7 @@ static int sync_io(unsigned int num_regions, struct io_region *where,
         io.error = 0;
         atomic_set(&io.count, 1); /* see dispatch_io() */
         io.sleeper = current;
+        io.client = client;
 
         dispatch_io(rw, num_regions, where, dp, &io, 1);
 
@@ -348,12 +371,15 @@ static int sync_io(unsigned int num_regions, struct io_region *where,
         if (atomic_read(&io.count))
                 return -EINTR;
 
-        *error_bits = io.error;
+        if (error_bits)
+                *error_bits = io.error;
+
         return io.error ? -EIO : 0;
 }
 
-static int async_io(unsigned int num_regions, struct io_region *where, int rw,
-             struct dpages *dp, io_notify_fn fn, void *context)
+static int async_io(struct dm_io_client *client, unsigned int num_regions,
+                    struct io_region *where, int rw, struct dpages *dp,
+                    io_notify_fn fn, void *context)
 {
         struct io *io;
 
@@ -363,10 +389,11 @@ static int async_io(unsigned int num_regions, struct io_region *where, int rw,
                 return -EIO;
         }
 
-        io = mempool_alloc(_io_pool, GFP_NOIO);
+        io = mempool_alloc(io_pool(client), GFP_NOIO);
         io->error = 0;
         atomic_set(&io->count, 1); /* see dispatch_io() */
         io->sleeper = NULL;
+        io->client = client;
         io->callback = fn;
         io->context = context;
 
@@ -380,7 +407,7 @@ int dm_io_sync(unsigned int num_regions, struct io_region *where, int rw,
 {
         struct dpages dp;
         list_dp_init(&dp, pl, offset);
-        return sync_io(num_regions, where, rw, &dp, error_bits);
+        return sync_io(NULL, num_regions, where, rw, &dp, error_bits);
 }
 
 int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where, int rw,
@@ -388,7 +415,7 @@ int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where, int rw,
 {
         struct dpages dp;
         bvec_dp_init(&dp, bvec);
-        return sync_io(num_regions, where, rw, &dp, error_bits);
+        return sync_io(NULL, num_regions, where, rw, &dp, error_bits);
 }
 
 int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw,
@@ -396,7 +423,7 @@ int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw,
 {
         struct dpages dp;
         vm_dp_init(&dp, data);
-        return sync_io(num_regions, where, rw, &dp, error_bits);
+        return sync_io(NULL, num_regions, where, rw, &dp, error_bits);
 }
 
 int dm_io_async(unsigned int num_regions, struct io_region *where, int rw,
@@ -405,7 +432,7 @@ int dm_io_async(unsigned int num_regions, struct io_region *where, int rw,
 {
         struct dpages dp;
         list_dp_init(&dp, pl, offset);
-        return async_io(num_regions, where, rw, &dp, fn, context);
+        return async_io(NULL, num_regions, where, rw, &dp, fn, context);
 }
 
 int dm_io_async_bvec(unsigned int num_regions, struct io_region *where, int rw,
@@ -413,7 +440,7 @@ int dm_io_async_bvec(unsigned int num_regions, struct io_region *where, int rw,
 {
         struct dpages dp;
         bvec_dp_init(&dp, bvec);
-        return async_io(num_regions, where, rw, &dp, fn, context);
+        return async_io(NULL, num_regions, where, rw, &dp, fn, context);
 }
 
 int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw,
@@ -421,7 +448,7 @@ int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw,
 {
         struct dpages dp;
         vm_dp_init(&dp, data);
-        return async_io(num_regions, where, rw, &dp, fn, context);
+        return async_io(NULL, num_regions, where, rw, &dp, fn, context);
 }
 
 EXPORT_SYMBOL(dm_io_get);