[PATCH] dm snapshot: allow zero chunk_size
The chunk size of snapshots cannot be changed so it is redundant to require it
as a parameter when activating an existing snapshot. Allow a value of zero in
this case and ignore it. For a new snapshot, use a default value if zero is
specified.
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 7c14867..89f8dd1 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -398,21 +398,60 @@
}
}
+static int set_chunk_size(struct dm_snapshot *s, const char *chunk_size_arg,
+ char **error)
+{
+ unsigned long chunk_size;
+ char *value;
+
+ 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) {
+ s->chunk_size = s->chunk_mask = s->chunk_shift = 0;
+ return 0;
+ }
+
+ /*
+ * Chunk size must be multiple of page size. Silently
+ * round up if it's not.
+ */
+ chunk_size = round_up(chunk_size, PAGE_SIZE >> 9);
+
+ /* Check chunk_size is a power of 2 */
+ if (chunk_size & (chunk_size - 1)) {
+ *error = "Chunk size is not a power of 2";
+ return -EINVAL;
+ }
+
+ /* Validate the chunk size against the device block size */
+ if (chunk_size % (bdev_hardsect_size(s->cow->bdev) >> 9)) {
+ *error = "Chunk size is not a multiple of device blocksize";
+ return -EINVAL;
+ }
+
+ s->chunk_size = chunk_size;
+ s->chunk_mask = chunk_size - 1;
+ s->chunk_shift = ffs(chunk_size) - 1;
+
+ return 0;
+}
+
/*
* Construct a snapshot mapping: <origin_dev> <COW-dev> <p/n> <chunk-size>
*/
static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
struct dm_snapshot *s;
- unsigned long chunk_size;
int r = -EINVAL;
char persistent;
char *origin_path;
char *cow_path;
- char *value;
- int blocksize;
- if (argc < 4) {
+ if (argc != 4) {
ti->error = "requires exactly 4 arguments";
r = -EINVAL;
goto bad1;
@@ -428,13 +467,6 @@
goto bad1;
}
- chunk_size = simple_strtoul(argv[3], &value, 10);
- if (chunk_size == 0 || value == NULL) {
- ti->error = "Invalid chunk size";
- r = -EINVAL;
- goto bad1;
- }
-
s = kmalloc(sizeof(*s), GFP_KERNEL);
if (s == NULL) {
ti->error = "Cannot allocate snapshot context private "
@@ -457,31 +489,11 @@
goto bad2;
}
- /*
- * Chunk size must be multiple of page size. Silently
- * round up if it's not.
- */
- chunk_size = round_up(chunk_size, PAGE_SIZE >> 9);
-
- /* Validate the chunk size against the device block size */
- blocksize = s->cow->bdev->bd_disk->queue->hardsect_size;
- if (chunk_size % (blocksize >> 9)) {
- ti->error = "Chunk size is not a multiple of device blocksize";
- r = -EINVAL;
+ r = set_chunk_size(s, argv[3], &ti->error);
+ if (r)
goto bad3;
- }
- /* Check chunk_size is a power of 2 */
- if (chunk_size & (chunk_size - 1)) {
- ti->error = "Chunk size is not a power of 2";
- r = -EINVAL;
- goto bad3;
- }
-
- s->chunk_size = chunk_size;
- s->chunk_mask = chunk_size - 1;
s->type = persistent;
- s->chunk_shift = ffs(chunk_size) - 1;
s->valid = 1;
s->active = 0;
@@ -496,16 +508,12 @@
goto bad3;
}
- /*
- * Check the persistent flag - done here because we need the iobuf
- * to check the LV header
- */
s->store.snap = s;
if (persistent == 'P')
- r = dm_create_persistent(&s->store, chunk_size);
+ r = dm_create_persistent(&s->store);
else
- r = dm_create_transient(&s->store, s, blocksize);
+ r = dm_create_transient(&s->store);
if (r) {
ti->error = "Couldn't create exception store";
@@ -1205,7 +1213,7 @@
static struct target_type origin_target = {
.name = "snapshot-origin",
- .version = {1, 4, 0},
+ .version = {1, 5, 0},
.module = THIS_MODULE,
.ctr = origin_ctr,
.dtr = origin_dtr,
@@ -1216,7 +1224,7 @@
static struct target_type snapshot_target = {
.name = "snapshot",
- .version = {1, 4, 0},
+ .version = {1, 5, 0},
.module = THIS_MODULE,
.ctr = snapshot_ctr,
.dtr = snapshot_dtr,