From: Mark McLoughlin <[email protected]>
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 <[email protected]>
Signed-off-by: Alasdair G Kergon <[email protected]>
Index: linux-2.6.18-rc7/drivers/md/dm-exception-store.c
===================================================================
--- linux-2.6.18-rc7.orig/drivers/md/dm-exception-store.c 2006-09-14 20:25:35.000000000 +0100
+++ linux-2.6.18-rc7/drivers/md/dm-exception-store.c 2006-09-14 20:29:57.000000000 +0100
@@ -17,6 +17,7 @@
#include <linux/slab.h>
#define DM_MSG_PREFIX "snapshots"
+#define DM_CHUNK_SIZE_DEFAULT_SECTORS 32 /* 16KB */
/*-----------------------------------------------------------------
* Persistent snapshots, by persistent we mean that the snapshot
@@ -150,6 +151,7 @@ static int alloc_area(struct pstore *ps)
static void free_area(struct pstore *ps)
{
vfree(ps->area);
+ ps->area = NULL;
}
/*
@@ -198,48 +200,79 @@ static int read_header(struct pstore *ps
int r;
struct disk_header *dh;
chunk_t chunk_size;
+ int chunk_size_supplied = 1;
- r = chunk_io(ps, 0, READ);
+ /*
+ * Use default chunk size (or hardsect_size, if larger) if none supplied
+ */
+ if (!ps->snap->chunk_size) {
+ ps->snap->chunk_size = max(DM_CHUNK_SIZE_DEFAULT_SECTORS,
+ bdev_hardsect_size(ps->snap->cow->bdev) >> 9);
+ ps->snap->chunk_mask = ps->snap->chunk_size - 1;
+ ps->snap->chunk_shift = ffs(ps->snap->chunk_size) - 1;
+ chunk_size_supplied = 0;
+ }
+
+ r = dm_io_get(sectors_to_pages(ps->snap->chunk_size));
if (r)
return r;
+ r = alloc_area(ps);
+ if (r)
+ goto bad1;
+
+ r = chunk_io(ps, 0, READ);
+ if (r)
+ goto bad2;
+
dh = (struct disk_header *) ps->area;
if (le32_to_cpu(dh->magic) == 0) {
*new_snapshot = 1;
+ return 0;
+ }
- } else if (le32_to_cpu(dh->magic) == SNAP_MAGIC) {
- *new_snapshot = 0;
- ps->valid = le32_to_cpu(dh->valid);
- ps->version = le32_to_cpu(dh->version);
- chunk_size = le32_to_cpu(dh->chunk_size);
- if (ps->snap->chunk_size != chunk_size) {
- DMWARN("chunk size %llu in device metadata overrides "
- "table chunk size of %llu.",
- (unsigned long long)chunk_size,
- (unsigned long long)ps->snap->chunk_size);
-
- /* We had a bogus chunk_size. Fix stuff up. */
- dm_io_put(sectors_to_pages(ps->snap->chunk_size));
- free_area(ps);
-
- ps->snap->chunk_size = chunk_size;
- ps->snap->chunk_mask = chunk_size - 1;
- ps->snap->chunk_shift = ffs(chunk_size) - 1;
-
- r = alloc_area(ps);
- if (r)
- return r;
-
- r = dm_io_get(sectors_to_pages(chunk_size));
- if (r)
- return r;
- }
- } else {
- DMWARN("Invalid/corrupt snapshot");
+ if (le32_to_cpu(dh->magic) != SNAP_MAGIC) {
+ DMWARN("Invalid or corrupt snapshot");
r = -ENXIO;
+ goto bad2;
}
+ *new_snapshot = 0;
+ ps->valid = le32_to_cpu(dh->valid);
+ ps->version = le32_to_cpu(dh->version);
+ chunk_size = le32_to_cpu(dh->chunk_size);
+
+ if (!chunk_size_supplied || ps->snap->chunk_size == chunk_size)
+ return 0;
+
+ DMWARN("chunk size %llu in device metadata overrides "
+ "table chunk size of %llu.",
+ (unsigned long long)chunk_size,
+ (unsigned long long)ps->snap->chunk_size);
+
+ /* We had a bogus chunk_size. Fix stuff up. */
+ dm_io_put(sectors_to_pages(ps->snap->chunk_size));
+ free_area(ps);
+
+ ps->snap->chunk_size = chunk_size;
+ ps->snap->chunk_mask = chunk_size - 1;
+ ps->snap->chunk_shift = ffs(chunk_size) - 1;
+
+ r = dm_io_get(sectors_to_pages(chunk_size));
+ if (r)
+ return r;
+
+ r = alloc_area(ps);
+ if (r)
+ goto bad1;
+
+ return 0;
+
+bad2:
+ free_area(ps);
+bad1:
+ dm_io_put(sectors_to_pages(ps->snap->chunk_size));
return r;
}
@@ -547,32 +580,22 @@ static void persistent_drop(struct excep
DMWARN("write header failed");
}
-int dm_create_persistent(struct exception_store *store, uint32_t chunk_size)
+int dm_create_persistent(struct exception_store *store)
{
- int r;
struct pstore *ps;
- r = dm_io_get(sectors_to_pages(chunk_size));
- if (r)
- return r;
-
/* allocate the pstore */
ps = kmalloc(sizeof(*ps), GFP_KERNEL);
- if (!ps) {
- r = -ENOMEM;
- goto bad;
- }
+ if (!ps)
+ return -ENOMEM;
ps->snap = store->snap;
ps->valid = 1;
ps->version = SNAPSHOT_DISK_VERSION;
+ ps->area = NULL;
ps->next_free = 2; /* skipping the header and first area */
ps->current_committed = 0;
- r = alloc_area(ps);
- if (r)
- goto bad;
-
ps->callback_count = 0;
atomic_set(&ps->pending_count, 0);
ps->callbacks = NULL;
@@ -586,13 +609,6 @@ int dm_create_persistent(struct exceptio
store->context = ps;
return 0;
-
- bad:
- dm_io_put(sectors_to_pages(chunk_size));
- if (ps && ps->area)
- free_area(ps);
- kfree(ps);
- return r;
}
/*-----------------------------------------------------------------
@@ -642,18 +658,16 @@ static void transient_fraction_full(stru
*denominator = get_dev_size(store->snap->cow->bdev);
}
-int dm_create_transient(struct exception_store *store,
- struct dm_snapshot *s, int blocksize)
+int dm_create_transient(struct exception_store *store)
{
struct transient_c *tc;
- memset(store, 0, sizeof(*store));
store->destroy = transient_destroy;
store->read_metadata = transient_read_metadata;
store->prepare_exception = transient_prepare;
store->commit_exception = transient_commit;
+ store->drop_snapshot = NULL;
store->fraction_full = transient_fraction_full;
- store->snap = s;
tc = kmalloc(sizeof(struct transient_c), GFP_KERNEL);
if (!tc)
Index: linux-2.6.18-rc7/drivers/md/dm-snap.c
===================================================================
--- linux-2.6.18-rc7.orig/drivers/md/dm-snap.c 2006-09-14 20:26:20.000000000 +0100
+++ linux-2.6.18-rc7/drivers/md/dm-snap.c 2006-09-14 20:29:57.000000000 +0100
@@ -398,21 +398,60 @@ static void read_snapshot_metadata(struc
}
}
+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
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
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;
- 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;
+ r = set_chunk_size(s, argv[3], &ti->error);
+ if (r)
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
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_targe
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,
Index: linux-2.6.18-rc7/drivers/md/dm-snap.h
===================================================================
--- linux-2.6.18-rc7.orig/drivers/md/dm-snap.h 2006-09-14 20:25:35.000000000 +0100
+++ linux-2.6.18-rc7/drivers/md/dm-snap.h 2006-09-14 20:29:57.000000000 +0100
@@ -128,10 +128,9 @@ int dm_add_exception(struct dm_snapshot
* Constructor and destructor for the default persistent
* store.
*/
-int dm_create_persistent(struct exception_store *store, uint32_t chunk_size);
+int dm_create_persistent(struct exception_store *store);
-int dm_create_transient(struct exception_store *store,
- struct dm_snapshot *s, int blocksize);
+int dm_create_transient(struct exception_store *store);
/*
* Return the number of sectors in the device.
-
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