From 4c7e3bf44d0ae227ea1ee87c2197212e65d043d7 Mon Sep 17 00:00:00 2001 From: Mark McLoughlin Date: Tue, 3 Oct 2006 01:15:25 -0700 Subject: [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 ++++++++++++++++++++++------------------ 1 file changed, 69 insertions(+), 55 deletions(-) (limited to 'drivers/md/dm-exception-store.c') diff --git a/drivers/md/dm-exception-store.c b/drivers/md/dm-exception-store.c index d12379b5cdb..8b4cd02f75a 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) -- cgit v1.2.3