From 4c7e3bf44d0ae227ea1ee87c2197212e65d043d7 Mon Sep 17 00:00:00 2001 From: Mark McLoughlin Date: Tue, 3 Oct 2006 01:15:25 -0700 Subject: [PATCH] [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 Signed-off-by: Alasdair G Kergon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/md/dm-exception-store.c | 124 ++++++++++++++++++-------------- drivers/md/dm-snap.c | 90 ++++++++++++----------- drivers/md/dm-snap.h | 5 +- 3 files changed, 120 insertions(+), 99 deletions(-) diff --git a/drivers/md/dm-exception-store.c b/drivers/md/dm-exception-store.c index d12379b5cd..8b4cd02f75 100644 --- a/drivers/md/dm-exception-store.c +++ b/drivers/md/dm-exception-store.c @@ -17,6 +17,7 @@ #include #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 *new_snapshot) 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 exception_store *store) 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 exception_store *store, uint32_t chunk_size) 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(struct exception_store *store, *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) diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c index 7c14867b59..89f8dd1bfa 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -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:

*/ 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; - 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 *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, diff --git a/drivers/md/dm-snap.h b/drivers/md/dm-snap.h index fdec1e2dc8..221eb8880c 100644 --- a/drivers/md/dm-snap.h +++ b/drivers/md/dm-snap.h @@ -128,10 +128,9 @@ int dm_add_exception(struct dm_snapshot *s, chunk_t old, chunk_t new); * 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. -- 2.39.5