s2io: reindented misleading for loop

[linux-2.6-omap-h63xx.git] / drivers / md / dm-exception-store.c

diff --git a/drivers/md/dm-exception-store.c b/drivers/md/dm-exception-store.c
index cb05b744deaa3395199f09d10997265bd6b205e1..41f408068a7c9c2329c61eb7e3eb47a82af6e280 100644 (file)
--- a/drivers/md/dm-exception-store.c
+++ b/drivers/md/dm-exception-store.c
@@ -9,13 +9,13 @@
 
 #include "dm.h"
 #include "dm-snap.h"
-#include "dm-io.h"
-#include "kcopyd.h"
 
 #include <linux/mm.h>
 #include <linux/pagemap.h>
 #include <linux/vmalloc.h>
 #include <linux/slab.h>
+#include <linux/dm-io.h>
+#include <linux/dm-kcopyd.h>
 
 #define DM_MSG_PREFIX "snapshots"
 #define DM_CHUNK_SIZE_DEFAULT_SECTORS 32       /* 16KB */
@@ -125,11 +125,13 @@ struct pstore {
        uint32_t callback_count;
        struct commit_callback *callbacks;
        struct dm_io_client *io_client;
+
+       struct workqueue_struct *metadata_wq;
 };
 
 static unsigned sectors_to_pages(unsigned sectors)
 {
-       return sectors / (PAGE_SIZE >> 9);
+       return DIV_ROUND_UP(sectors, PAGE_SIZE >> 9);
 }
 
 static int alloc_area(struct pstore *ps)
@@ -156,12 +158,26 @@ static void free_area(struct pstore *ps)
        ps->area = NULL;
 }
 
+struct mdata_req {
+       struct dm_io_region *where;
+       struct dm_io_request *io_req;
+       struct work_struct work;
+       int result;
+};
+
+static void do_metadata(struct work_struct *work)
+{
+       struct mdata_req *req = container_of(work, struct mdata_req, work);
+
+       req->result = dm_io(req->io_req, 1, req->where, NULL);
+}
+
 /*
  * Read or write a chunk aligned and sized block of data from a device.
  */
-static int chunk_io(struct pstore *ps, uint32_t chunk, int rw)
+static int chunk_io(struct pstore *ps, uint32_t chunk, int rw, int metadata)
 {
-       struct io_region where = {
+       struct dm_io_region where = {
                .bdev = ps->snap->cow->bdev,
                .sector = ps->snap->chunk_size * chunk,
                .count = ps->snap->chunk_size,
@@ -173,8 +189,23 @@ static int chunk_io(struct pstore *ps, uint32_t chunk, int rw)
                .client = ps->io_client,
                .notify.fn = NULL,
        };
+       struct mdata_req req;
+
+       if (!metadata)
+               return dm_io(&io_req, 1, &where, NULL);
+
+       req.where = &where;
+       req.io_req = &io_req;
 
-       return dm_io(&io_req, 1, &where, NULL);
+       /*
+        * Issue the synchronous I/O from a different thread
+        * to avoid generic_make_request recursion.
+        */
+       INIT_WORK(&req.work, do_metadata);
+       queue_work(ps->metadata_wq, &req.work);
+       flush_workqueue(ps->metadata_wq);
+
+       return req.result;
 }
 
 /*
@@ -189,7 +220,7 @@ static int area_io(struct pstore *ps, uint32_t area, int rw)
        /* convert a metadata area index to a chunk index */
        chunk = 1 + ((ps->exceptions_per_area + 1) * area);
 
-       r = chunk_io(ps, chunk, rw);
+       r = chunk_io(ps, chunk, rw, 0);
        if (r)
                return r;
 
@@ -230,7 +261,7 @@ static int read_header(struct pstore *ps, int *new_snapshot)
        if (r)
                return r;
 
-       r = chunk_io(ps, 0, READ);
+       r = chunk_io(ps, 0, READ, 1);
        if (r)
                goto bad;
 
@@ -292,7 +323,7 @@ static int write_header(struct pstore *ps)
        dh->version = cpu_to_le32(ps->version);
        dh->chunk_size = cpu_to_le32(ps->snap->chunk_size);
 
-       return chunk_io(ps, 0, WRITE);
+       return chunk_io(ps, 0, WRITE, 1);
 }
 
 /*
@@ -409,6 +440,7 @@ static void persistent_destroy(struct exception_store *store)
 {
        struct pstore *ps = get_info(store);
 
+       destroy_workqueue(ps->metadata_wq);
        dm_io_client_destroy(ps->io_client);
        vfree(ps->callbacks);
        free_area(ps);
@@ -417,7 +449,7 @@ static void persistent_destroy(struct exception_store *store)
 
 static int persistent_read_metadata(struct exception_store *store)
 {
-       int r, new_snapshot;
+       int r, uninitialized_var(new_snapshot);
        struct pstore *ps = get_info(store);
 
        /*
@@ -457,17 +489,18 @@ static int persistent_read_metadata(struct exception_store *store)
                /*
                 * Sanity checks.
                 */
-               if (!ps->valid) {
-                       DMWARN("snapshot is marked invalid");
-                       return -EINVAL;
-               }
-
                if (ps->version != SNAPSHOT_DISK_VERSION) {
                        DMWARN("unable to handle snapshot disk version %d",
                               ps->version);
                        return -EINVAL;
                }
 
+               /*
+                * Metadata are valid, but snapshot is invalidated
+                */
+               if (!ps->valid)
+                       return 1;
+
                /*
                 * Read the metadata.
                 */
@@ -588,6 +621,13 @@ int dm_create_persistent(struct exception_store *store)
        atomic_set(&ps->pending_count, 0);
        ps->callbacks = NULL;
 
+       ps->metadata_wq = create_singlethread_workqueue("ksnaphd");
+       if (!ps->metadata_wq) {
+               kfree(ps);
+               DMERR("couldn't start header metadata update thread");
+               return -ENOMEM;
+       }
+
        store->destroy = persistent_destroy;
        store->read_metadata = persistent_read_metadata;
        store->prepare_exception = persistent_prepare;