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[dm-devel] [PATCH] dm snapshot: use unsigned integer chunk size



Use unsigned integer chunk size.

Maximum chunk size is 512kB, there won't ever be need to use 4GB chunk size,
so the number can be 32-bit. This fixes compiler failure on 32-bit systems
with large block devices.

Signed-off-by: Mikulas Patocka <mpatocka redhat com>
Signed-off-by: Mike Snitzer <snitzer redhat com>
Reviewed-by: Jonathan Brassow <jbrassow redhat com>

---
NOTE: this patch was made to go _before_ the snapshot exception
patchset; I'll be sending [v2] of 2 patches from that series.  They
needed small adjustments now that this chunk_size patch comes before
them.
---
 drivers/md/dm-exception-store.c |   23 +++++++++++------------
 drivers/md/dm-exception-store.h |    8 ++++----
 drivers/md/dm-snap-persistent.c |   16 ++++++++--------
 drivers/md/dm-snap.c            |    4 ++--
 4 files changed, 25 insertions(+), 26 deletions(-)

Index: linux-2.6/drivers/md/dm-snap.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-snap.c
+++ linux-2.6/drivers/md/dm-snap.c
@@ -527,7 +527,7 @@ static int dm_add_exception(void *contex
 static sector_t __minimum_chunk_size(struct origin *o)
 {
 	struct dm_snapshot *snap;
-	sector_t chunk_size = 0;
+	unsigned chunk_size = 0;
 
 	if (o)
 		list_for_each_entry(snap, &o->snapshots, list)
@@ -975,7 +975,7 @@ static void start_copy(struct dm_snap_pe
 
 	src.bdev = bdev;
 	src.sector = chunk_to_sector(s->store, pe->e.old_chunk);
-	src.count = min(s->store->chunk_size, dev_size - src.sector);
+	src.count = min((sector_t)s->store->chunk_size, dev_size - src.sector);
 
 	dest.bdev = s->store->cow->bdev;
 	dest.sector = chunk_to_sector(s->store, pe->e.new_chunk);
Index: linux-2.6/drivers/md/dm-exception-store.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-exception-store.c
+++ linux-2.6/drivers/md/dm-exception-store.c
@@ -141,48 +141,47 @@ EXPORT_SYMBOL(dm_exception_store_type_un
 static int set_chunk_size(struct dm_exception_store *store,
 			  const char *chunk_size_arg, char **error)
 {
-	unsigned long chunk_size_ulong;
+	unsigned chunk_size;
 	char *value;
 
-	chunk_size_ulong = simple_strtoul(chunk_size_arg, &value, 10);
+	chunk_size = simple_strtoul(chunk_size_arg, &value, 10);
 	if (*chunk_size_arg == '\0' || *value != '\0') {
 		*error = "Invalid chunk size";
 		return -EINVAL;
 	}
 
-	if (!chunk_size_ulong) {
+	if (!chunk_size) {
 		store->chunk_size = store->chunk_mask = store->chunk_shift = 0;
 		return 0;
 	}
 
-	return dm_exception_store_set_chunk_size(store, chunk_size_ulong,
-						 error);
+	return dm_exception_store_set_chunk_size(store, chunk_size, error);
 }
 
 int dm_exception_store_set_chunk_size(struct dm_exception_store *store,
-				      unsigned long chunk_size_ulong,
+				      unsigned chunk_size,
 				      char **error)
 {
 	/* Check chunk_size is a power of 2 */
-	if (!is_power_of_2(chunk_size_ulong)) {
+	if (!is_power_of_2(chunk_size)) {
 		*error = "Chunk size is not a power of 2";
 		return -EINVAL;
 	}
 
 	/* Validate the chunk size against the device block size */
-	if (chunk_size_ulong % (bdev_logical_block_size(store->cow->bdev) >> 9)) {
+	if (chunk_size % (bdev_logical_block_size(store->cow->bdev) >> 9)) {
 		*error = "Chunk size is not a multiple of device blocksize";
 		return -EINVAL;
 	}
 
-	if (chunk_size_ulong > INT_MAX >> SECTOR_SHIFT) {
+	if (chunk_size > INT_MAX >> SECTOR_SHIFT) {
 		*error = "Chunk size is too high";
 		return -EINVAL;
 	}
 
-	store->chunk_size = chunk_size_ulong;
-	store->chunk_mask = chunk_size_ulong - 1;
-	store->chunk_shift = ffs(chunk_size_ulong) - 1;
+	store->chunk_size = chunk_size;
+	store->chunk_mask = chunk_size - 1;
+	store->chunk_shift = ffs(chunk_size) - 1;
 
 	return 0;
 }
Index: linux-2.6/drivers/md/dm-exception-store.h
===================================================================
--- linux-2.6.orig/drivers/md/dm-exception-store.h
+++ linux-2.6/drivers/md/dm-exception-store.h
@@ -101,9 +101,9 @@ struct dm_exception_store {
 	struct dm_dev *cow;
 
 	/* Size of data blocks saved - must be a power of 2 */
-	chunk_t chunk_size;
-	chunk_t chunk_mask;
-	chunk_t chunk_shift;
+	unsigned chunk_size;
+	unsigned chunk_mask;
+	unsigned chunk_shift;
 
 	void *context;
 };
@@ -169,7 +169,7 @@ int dm_exception_store_type_register(str
 int dm_exception_store_type_unregister(struct dm_exception_store_type *type);
 
 int dm_exception_store_set_chunk_size(struct dm_exception_store *store,
-				      unsigned long chunk_size_ulong,
+				      unsigned chunk_size,
 				      char **error);
 
 int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
Index: linux-2.6/drivers/md/dm-snap-persistent.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-snap-persistent.c
+++ linux-2.6/drivers/md/dm-snap-persistent.c
@@ -284,12 +284,13 @@ static int read_header(struct pstore *ps
 {
 	int r;
 	struct disk_header *dh;
-	chunk_t chunk_size;
+	unsigned chunk_size;
 	int chunk_size_supplied = 1;
 	char *chunk_err;
 
 	/*
-	 * Use default chunk size (or hardsect_size, if larger) if none supplied
+	 * Use default chunk size (or logical_block_size, if larger)
+	 * if none supplied
 	 */
 	if (!ps->store->chunk_size) {
 		ps->store->chunk_size = max(DM_CHUNK_SIZE_DEFAULT_SECTORS,
@@ -334,10 +335,9 @@ static int read_header(struct pstore *ps
 		return 0;
 
 	if (chunk_size_supplied)
-		DMWARN("chunk size %llu in device metadata overrides "
-		       "table chunk size of %llu.",
-		       (unsigned long long)chunk_size,
-		       (unsigned long long)ps->store->chunk_size);
+		DMWARN("chunk size %u in device metadata overrides "
+		       "table chunk size of %u.",
+		       chunk_size, ps->store->chunk_size);
 
 	/* We had a bogus chunk_size. Fix stuff up. */
 	free_area(ps);
@@ -345,8 +345,8 @@ static int read_header(struct pstore *ps
 	r = dm_exception_store_set_chunk_size(ps->store, chunk_size,
 					      &chunk_err);
 	if (r) {
-		DMERR("invalid on-disk chunk size %llu: %s.",
-		      (unsigned long long)chunk_size, chunk_err);
+		DMERR("invalid on-disk chunk size %u: %s.",
+		      chunk_size, chunk_err);
 		return r;
 	}
 


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