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[PATCH] dm snapshot: allow zero chunk_size

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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>
This commit is contained in:
Mark McLoughlin
2006-10-03 01:15:25 -07:00
committed by Linus Torvalds
parent 92c060a692
commit 4c7e3bf44d
3 changed files with 122 additions and 101 deletions
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90
drivers/md/dm-snap.c
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@@ -398,21 +398,60 @@ static void read_snapshot_metadata(struct dm_snapshot *s)
}
}
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 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
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 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
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 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
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 int origin_status(struct dm_target *ti, status_type_t type, char *result,
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 origin_target = {
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,