diff options
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/Makefile | 3 | ||||
| -rw-r--r-- | drivers/md/dm-exception-store.c | 749 | ||||
| -rw-r--r-- | drivers/md/dm-exception-store.h | 9 | ||||
| -rw-r--r-- | drivers/md/dm-snap-persistent.c | 694 | ||||
| -rw-r--r-- | drivers/md/dm-snap-transient.c | 95 | ||||
| -rw-r--r-- | drivers/md/dm-snap.c | 20 |
6 files changed, 833 insertions, 737 deletions
diff --git a/drivers/md/Makefile b/drivers/md/Makefile index 63f0ae94415..72880b7e28d 100644 --- a/drivers/md/Makefile +++ b/drivers/md/Makefile @@ -5,7 +5,8 @@ dm-mod-objs := dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \ dm-ioctl.o dm-io.o dm-kcopyd.o dm-sysfs.o dm-multipath-objs := dm-path-selector.o dm-mpath.o -dm-snapshot-objs := dm-snap.o dm-exception-store.o +dm-snapshot-objs := dm-snap.o dm-exception-store.o dm-snap-transient.o \ + dm-snap-persistent.o dm-mirror-objs := dm-raid1.o md-mod-objs := md.o bitmap.o raid456-objs := raid5.o raid6algos.o raid6recov.o raid6tables.o \ diff --git a/drivers/md/dm-exception-store.c b/drivers/md/dm-exception-store.c index c5c9a265231..74777e0f80d 100644 --- a/drivers/md/dm-exception-store.c +++ b/drivers/md/dm-exception-store.c @@ -1,757 +1,46 @@ /* - * dm-exception-store.c - * * Copyright (C) 2001-2002 Sistina Software (UK) Limited. - * Copyright (C) 2006 Red Hat GmbH + * Copyright (C) 2006-2008 Red Hat GmbH * * This file is released under the GPL. */ #include "dm-exception-store.h" -#include "dm-snap.h" #include <linux/mm.h> #include <linux/pagemap.h> #include <linux/vmalloc.h> #include <linux/slab.h> -#include <linux/dm-io.h> -#include <linux/dm-kcopyd.h> - -#define DM_MSG_PREFIX "snapshots" -#define DM_CHUNK_SIZE_DEFAULT_SECTORS 32 /* 16KB */ - -/*----------------------------------------------------------------- - * Persistent snapshots, by persistent we mean that the snapshot - * will survive a reboot. - *---------------------------------------------------------------*/ - -/* - * We need to store a record of which parts of the origin have - * been copied to the snapshot device. The snapshot code - * requires that we copy exception chunks to chunk aligned areas - * of the COW store. It makes sense therefore, to store the - * metadata in chunk size blocks. - * - * There is no backward or forward compatibility implemented, - * snapshots with different disk versions than the kernel will - * not be usable. It is expected that "lvcreate" will blank out - * the start of a fresh COW device before calling the snapshot - * constructor. - * - * The first chunk of the COW device just contains the header. - * After this there is a chunk filled with exception metadata, - * followed by as many exception chunks as can fit in the - * metadata areas. - * - * All on disk structures are in little-endian format. The end - * of the exceptions info is indicated by an exception with a - * new_chunk of 0, which is invalid since it would point to the - * header chunk. - */ - -/* - * Magic for persistent snapshots: "SnAp" - Feeble isn't it. - */ -#define SNAP_MAGIC 0x70416e53 - -/* - * The on-disk version of the metadata. - */ -#define SNAPSHOT_DISK_VERSION 1 - -struct disk_header { - uint32_t magic; - - /* - * Is this snapshot valid. There is no way of recovering - * an invalid snapshot. - */ - uint32_t valid; - - /* - * Simple, incrementing version. no backward - * compatibility. - */ - uint32_t version; - - /* In sectors */ - uint32_t chunk_size; -}; - -struct disk_exception { - uint64_t old_chunk; - uint64_t new_chunk; -}; - -struct commit_callback { - void (*callback)(void *, int success); - void *context; -}; - -/* - * The top level structure for a persistent exception store. - */ -struct pstore { - struct dm_snapshot *snap; /* up pointer to my snapshot */ - int version; - int valid; - uint32_t exceptions_per_area; - - /* - * Now that we have an asynchronous kcopyd there is no - * need for large chunk sizes, so it wont hurt to have a - * whole chunks worth of metadata in memory at once. - */ - void *area; - - /* - * An area of zeros used to clear the next area. - */ - void *zero_area; - - /* - * Used to keep track of which metadata area the data in - * 'chunk' refers to. - */ - chunk_t current_area; - - /* - * The next free chunk for an exception. - */ - chunk_t next_free; - - /* - * The index of next free exception in the current - * metadata area. - */ - uint32_t current_committed; - - atomic_t pending_count; - uint32_t callback_count; - struct commit_callback *callbacks; - struct dm_io_client *io_client; - - struct workqueue_struct *metadata_wq; -}; - -static unsigned sectors_to_pages(unsigned sectors) -{ - return DIV_ROUND_UP(sectors, PAGE_SIZE >> 9); -} - -static int alloc_area(struct pstore *ps) -{ - int r = -ENOMEM; - size_t len; - - len = ps->snap->chunk_size << SECTOR_SHIFT; - - /* - * Allocate the chunk_size block of memory that will hold - * a single metadata area. - */ - ps->area = vmalloc(len); - if (!ps->area) - return r; - - ps->zero_area = vmalloc(len); - if (!ps->zero_area) { - vfree(ps->area); - return r; - } - memset(ps->zero_area, 0, len); - - return 0; -} - -static void free_area(struct pstore *ps) -{ - vfree(ps->area); - ps->area = NULL; - vfree(ps->zero_area); - ps->zero_area = NULL; -} - -struct mdata_req { - struct dm_io_region *where; - struct dm_io_request *io_req; - struct work_struct work; - int result; -}; - -static void do_metadata(struct work_struct *work) -{ - struct mdata_req *req = container_of(work, struct mdata_req, work); - - req->result = dm_io(req->io_req, 1, req->where, NULL); -} - -/* - * Read or write a chunk aligned and sized block of data from a device. - */ -static int chunk_io(struct pstore *ps, chunk_t chunk, int rw, int metadata) -{ - struct dm_io_region where = { - .bdev = ps->snap->cow->bdev, - .sector = ps->snap->chunk_size * chunk, - .count = ps->snap->chunk_size, - }; - struct dm_io_request io_req = { - .bi_rw = rw, - .mem.type = DM_IO_VMA, - .mem.ptr.vma = ps->area, - .client = ps->io_client, - .notify.fn = NULL, - }; - struct mdata_req req; - - if (!metadata) - return dm_io(&io_req, 1, &where, NULL); - - req.where = &where; - req.io_req = &io_req; - - /* - * Issue the synchronous I/O from a different thread - * to avoid generic_make_request recursion. - */ - INIT_WORK(&req.work, do_metadata); - queue_work(ps->metadata_wq, &req.work); - flush_workqueue(ps->metadata_wq); - - return req.result; -} - -/* - * Convert a metadata area index to a chunk index. - */ -static chunk_t area_location(struct pstore *ps, chunk_t area) -{ - return 1 + ((ps->exceptions_per_area + 1) * area); -} - -/* - * Read or write a metadata area. Remembering to skip the first - * chunk which holds the header. - */ -static int area_io(struct pstore *ps, int rw) -{ - int r; - chunk_t chunk; - - chunk = area_location(ps, ps->current_area); - - r = chunk_io(ps, chunk, rw, 0); - if (r) - return r; - - return 0; -} - -static void zero_memory_area(struct pstore *ps) -{ - memset(ps->area, 0, ps->snap->chunk_size << SECTOR_SHIFT); -} - -static int zero_disk_area(struct pstore *ps, chunk_t area) -{ - struct dm_io_region where = { - .bdev = ps->snap->cow->bdev, - .sector = ps->snap->chunk_size * area_location(ps, area), - .count = ps->snap->chunk_size, - }; - struct dm_io_request io_req = { - .bi_rw = WRITE, - .mem.type = DM_IO_VMA, - .mem.ptr.vma = ps->zero_area, - .client = ps->io_client, - .notify.fn = NULL, - }; - - return dm_io(&io_req, 1, &where, NULL); -} - -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; - - /* - * 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; - } - - ps->io_client = dm_io_client_create(sectors_to_pages(ps->snap-> - chunk_size)); - if (IS_ERR(ps->io_client)) - return PTR_ERR(ps->io_client); - - r = alloc_area(ps); - if (r) - return r; - - r = chunk_io(ps, 0, READ, 1); - if (r) - goto bad; - - dh = (struct disk_header *) ps->area; - - if (le32_to_cpu(dh->magic) == 0) { - *new_snapshot = 1; - return 0; - } - - if (le32_to_cpu(dh->magic) != SNAP_MAGIC) { - DMWARN("Invalid or corrupt snapshot"); - r = -ENXIO; - goto bad; - } - - *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. */ - 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_client_resize(sectors_to_pages(ps->snap->chunk_size), - ps->io_client); - if (r) - return r; - - r = alloc_area(ps); - return r; - -bad: - free_area(ps); - return r; -} - -static int write_header(struct pstore *ps) -{ - struct disk_header *dh; - - memset(ps->area, 0, ps->snap->chunk_size << SECTOR_SHIFT); - - dh = (struct disk_header *) ps->area; - dh->magic = cpu_to_le32(SNAP_MAGIC); - dh->valid = cpu_to_le32(ps->valid); - dh->version = cpu_to_le32(ps->version); - dh->chunk_size = cpu_to_le32(ps->snap->chunk_size); - - return chunk_io(ps, 0, WRITE, 1); -} - -/* - * Access functions for the disk exceptions, these do the endian conversions. - */ -static struct disk_exception *get_exception(struct pstore *ps, uint32_t index) -{ - BUG_ON(index >= ps->exceptions_per_area); - - return ((struct disk_exception *) ps->area) + index; -} +#include <linux/device-mapper.h> -static void read_exception(struct pstore *ps, - uint32_t index, struct disk_exception *result) -{ - struct disk_exception *e = get_exception(ps, index); - - /* copy it */ - result->old_chunk = le64_to_cpu(e->old_chunk); - result->new_chunk = le64_to_cpu(e->new_chunk); -} - -static void write_exception(struct pstore *ps, - uint32_t index, struct disk_exception *de) -{ - struct disk_exception *e = get_exception(ps, index); - - /* copy it */ - e->old_chunk = cpu_to_le64(de->old_chunk); - e->new_chunk = cpu_to_le64(de->new_chunk); -} +#define DM_MSG_PREFIX "snapshot exception stores" -/* - * Registers the exceptions that are present in the current area. - * 'full' is filled in to indicate if the area has been - * filled. - */ -static int insert_exceptions(struct pstore *ps, int *full) +int dm_exception_store_init(void) { int r; - unsigned int i; - struct disk_exception de; - - /* presume the area is full */ - *full = 1; - - for (i = 0; i < ps->exceptions_per_area; i++) { - read_exception(ps, i, &de); - - /* - * If the new_chunk is pointing at the start of - * the COW device, where the first metadata area - * is we know that we've hit the end of the - * exceptions. Therefore the area is not full. - */ - if (de.new_chunk == 0LL) { - ps->current_committed = i; - *full = 0; - break; - } - - /* - * Keep track of the start of the free chunks. - */ - if (ps->next_free <= de.new_chunk) - ps->next_free = de.new_chunk + 1; - - /* - * Otherwise we add the exception to the snapshot. - */ - r = dm_add_exception(ps->snap, de.old_chunk, de.new_chunk); - if (r) - return r; - } - - return 0; -} - -static int read_exceptions(struct pstore *ps) -{ - int r, full = 1; - - /* - * Keeping reading chunks and inserting exceptions until - * we find a partially full area. - */ - for (ps->current_area = 0; full; ps->current_area++) { - r = area_io(ps, READ); - if (r) - return r; - r = insert_exceptions(ps, &full); - if (r) - return r; + r = dm_transient_snapshot_init(); + if (r) { + DMERR("Unable to register transient exception store type."); + goto transient_fail; } - ps->current_area--; - - return 0; -} - -static struct pstore *get_info(struct dm_exception_store *store) -{ - return (struct pstore *) store->context; -} - -static void persistent_fraction_full(struct dm_exception_store *store, - sector_t *numerator, sector_t *denominator) -{ - *numerator = get_info(store)->next_free * store->snap->chunk_size; - *denominator = get_dev_size(store->snap->cow->bdev); -} - -static void persistent_destroy(struct dm_exception_store *store) -{ - struct pstore *ps = get_info(store); - - destroy_workqueue(ps->metadata_wq); - dm_io_client_destroy(ps->io_client); - vfree(ps->callbacks); - free_area(ps); - kfree(ps); -} - -static int persistent_read_metadata(struct dm_exception_store *store) -{ - int r, uninitialized_var(new_snapshot); - struct pstore *ps = get_info(store); - - /* - * Read the snapshot header. - */ - r = read_header(ps, &new_snapshot); - if (r) - return r; - - /* - * Now we know correct chunk_size, complete the initialisation. - */ - ps->exceptions_per_area = (ps->snap->chunk_size << SECTOR_SHIFT) / - sizeof(struct disk_exception); - ps->callbacks = dm_vcalloc(ps->exceptions_per_area, - sizeof(*ps->callbacks)); - if (!ps->callbacks) - return -ENOMEM; - - /* - * Do we need to setup a new snapshot ? - */ - if (new_snapshot) { - r = write_header(ps); - if (r) { - DMWARN("write_header failed"); - return r; - } - - ps->current_area = 0; - zero_memory_area(ps); - r = zero_disk_area(ps, 0); - if (r) { - DMWARN("zero_disk_area(0) failed"); - return r; - } - } else { - /* - * Sanity checks. - */ - if (ps->version != SNAPSHOT_DISK_VERSION) { - DMWARN("unable to handle snapshot disk version %d", - ps->version); - return -EINVAL; - } - - /* - * Metadata are valid, but snapshot is invalidated - */ - if (!ps->valid) - return 1; - - /* - * Read the metadata. - */ - r = read_exceptions(ps); - if (r) - return r; + r = dm_persistent_snapshot_init(); + if (r) { + DMERR("Unable to register persistent exception store type"); + goto persistent_fail; } return 0; -} - -static int persistent_prepare(struct dm_exception_store *store, - struct dm_snap_exception *e) -{ - struct pstore *ps = get_info(store); - uint32_t stride; - chunk_t next_free; - sector_t size = get_dev_size(store->snap->cow->bdev); - - /* Is there enough room ? */ - if (size < ((ps->next_free + 1) * store->snap->chunk_size)) - return -ENOSPC; - e->new_chunk = ps->next_free; - - /* - * Move onto the next free pending, making sure to take - * into account the location of the metadata chunks. - */ - stride = (ps->exceptions_per_area + 1); - next_free = ++ps->next_free; - if (sector_div(next_free, stride) == 1) - ps->next_free++; - - atomic_inc(&ps->pending_count); - return 0; -} - -static void persistent_commit(struct dm_exception_store *store, - struct dm_snap_exception *e, - void (*callback) (void *, int success), - void *callback_context) -{ - unsigned int i; - struct pstore *ps = get_info(store); - struct disk_exception de; - struct commit_callback *cb; - - de.old_chunk = e->old_chunk; - de.new_chunk = e->new_chunk; - write_exception(ps, ps->current_committed++, &de); - - /* - * Add the callback to the back of the array. This code - * is the only place where the callback array is - * manipulated, and we know that it will never be called - * multiple times concurrently. - */ - cb = ps->callbacks + ps->callback_count++; - cb->callback = callback; - cb->context = callback_context; - - /* - * If there are exceptions in flight and we have not yet - * filled this metadata area there's nothing more to do. - */ - if (!atomic_dec_and_test(&ps->pending_count) && - (ps->current_committed != ps->exceptions_per_area)) - return; - - /* - * If we completely filled the current area, then wipe the next one. - */ - if ((ps->current_committed == ps->exceptions_per_area) && - zero_disk_area(ps, ps->current_area + 1)) - ps->valid = 0; - - /* - * Commit exceptions to disk. - */ - if (ps->valid && area_io(ps, WRITE)) - ps->valid = 0; - - /* - * Advance to the next area if this one is full. - */ - if (ps->current_committed == ps->exceptions_per_area) { - ps->current_committed = 0; - ps->current_area++; - zero_memory_area(ps); - } - - for (i = 0; i < ps->callback_count; i++) { - cb = ps->callbacks + i; - cb->callback(cb->context, ps->valid); - } - - ps->callback_count = 0; -} - -static void persistent_drop(struct dm_exception_store *store) -{ - struct pstore *ps = get_info(store); - - ps->valid = 0; - if (write_header(ps)) - DMWARN("write header failed"); -} - -int dm_create_persistent(struct dm_exception_store *store) -{ - struct pstore *ps; - - /* allocate the pstore */ - ps = kmalloc(sizeof(*ps), GFP_KERNEL); - 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; - - ps->callback_count = 0; - atomic_set(&ps->pending_count, 0); - ps->callbacks = NULL; - - ps->metadata_wq = create_singlethread_workqueue("ksnaphd"); - if (!ps->metadata_wq) { - kfree(ps); - DMERR("couldn't start header metadata update thread"); - return -ENOMEM; - } - - store->destroy = persistent_destroy; - store->read_metadata = persistent_read_metadata; - store->prepare_exception = persistent_prepare; - store->commit_exception = persistent_commit; - store->drop_snapshot = persistent_drop; - store->fraction_full = persistent_fraction_full; - store->context = ps; - - return 0; -} - -/*----------------------------------------------------------------- - * Implementation of the store for non-persistent snapshots. - *---------------------------------------------------------------*/ -struct transient_c { - sector_t next_free; -}; - -static void transient_destroy(struct dm_exception_store *store) -{ - kfree(store->context); -} - -static int transient_read_metadata(struct dm_exception_store *store) -{ - return 0; -} - -static int transient_prepare(struct dm_exception_store *store, - struct dm_snap_exception *e) -{ - struct transient_c *tc = (struct transient_c *) store->context; - sector_t size = get_dev_size(store->snap->cow->bdev); - - if (size < (tc->next_free + store->snap->chunk_size)) - return -1; - - e->new_chunk = sector_to_chunk(store->snap, tc->next_free); - tc->next_free += store->snap->chunk_size; - - return 0; -} - -static void transient_commit(struct dm_exception_store *store, - struct dm_snap_exception *e, - void (*callback) (void *, int success), - void *callback_context) -{ - /* Just succeed */ - callback(callback_context, 1); -} - -static void transient_fraction_full(struct dm_exception_store *store, - sector_t *numerator, sector_t *denominator) -{ - *numerator = ((struct transient_c *) store->context)->next_free; - *denominator = get_dev_size(store->snap->cow->bdev); +persistent_fail: + dm_persistent_snapshot_exit(); +transient_fail: + return r; } -int dm_create_transient(struct dm_exception_store *store) +void dm_exception_store_exit(void) { - struct transient_c *tc; - - 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; - - tc = kmalloc(sizeof(struct transient_c), GFP_KERNEL); - if (!tc) - return -ENOMEM; - - tc->next_free = 0; - store->context = tc; - - return 0; + dm_persistent_snapshot_exit(); + dm_transient_snapshot_exit(); } diff --git a/drivers/md/dm-exception-store.h b/drivers/md/dm-exception-store.h index 25677df8dd5..78d1acec77e 100644 --- a/drivers/md/dm-exception-store.h +++ b/drivers/md/dm-exception-store.h @@ -122,9 +122,18 @@ static inline void dm_consecutive_chunk_count_inc(struct dm_snap_exception *e) # endif +int dm_exception_store_init(void); +void dm_exception_store_exit(void); + /* * Two exception store implementations. */ +int dm_persistent_snapshot_init(void); +void dm_persistent_snapshot_exit(void); + +int dm_transient_snapshot_init(void); +void dm_transient_snapshot_exit(void); + int dm_create_persistent(struct dm_exception_store *store); int dm_create_transient(struct dm_exception_store *store); diff --git a/drivers/md/dm-snap-persistent.c b/drivers/md/dm-snap-persistent.c new file mode 100644 index 00000000000..57c946c69ee --- /dev/null +++ b/drivers/md/dm-snap-persistent.c @@ -0,0 +1,694 @@ +/* + * Copyright (C) 2001-2002 Sistina Software (UK) Limited. + * Copyright (C) 2006-2008 Red Hat GmbH + * + * This file is released under the GPL. + */ + +#include "dm-exception-store.h" +#include "dm-snap.h" + +#include <linux/mm.h> +#include <linux/pagemap.h> +#include <linux/vmalloc.h> +#include <linux/slab.h> +#include <linux/dm-io.h> + +#define DM_MSG_PREFIX "persistent snapshot" +#define DM_CHUNK_SIZE_DEFAULT_SECTORS 32 /* 16KB */ + +/*----------------------------------------------------------------- + * Persistent snapshots, by persistent we mean that the snapshot + * will survive a reboot. + *---------------------------------------------------------------*/ + +/* + * We need to store a record of which parts of the origin have + * been copied to the snapshot device. The snapshot code + * requires that we copy exception chunks to chunk aligned areas + * of the COW store. It makes sense therefore, to store the + * metadata in chunk size blocks. + * + * There is no backward or forward compatibility implemented, + * snapshots with different disk versions than the kernel will + * not be usable. It is expected that "lvcreate" will blank out + * the start of a fresh COW device before calling the snapshot + * constructor. + * + * The first chunk of the COW device just contains the header. + * After this there is a chunk filled with exception metadata, + * followed by as many exception chunks as can fit in the + * metadata areas. + * + * All on disk structures are in little-endian format. The end + * of the exceptions info is indicated by an exception with a + * new_chunk of 0, which is invalid since it would point to the + * header chunk. + */ + +/* + * Magic for persistent snapshots: "SnAp" - Feeble isn't it. + */ +#define SNAP_MAGIC 0x70416e53 + +/* + * The on-disk version of the metadata. + */ +#define SNAPSHOT_DISK_VERSION 1 + +struct disk_header { + uint32_t magic; + + /* + * Is this snapshot valid. There is no way of recovering + * an invalid snapshot. + */ + uint32_t valid; + + /* + * Simple, incrementing version. no backward + * compatibility. + */ + uint32_t version; + + /* In sectors */ + uint32_t chunk_size; +}; + +struct disk_exception { + uint64_t old_chunk; + uint64_t new_chunk; +}; + +struct commit_callback { + void (*callback)(void *, int success); + void *context; +}; + +/* + * The top level structure for a persistent exception store. + */ +struct pstore { + struct dm_snapshot *snap; /* up pointer to my snapshot */ + int version; + int valid; + uint32_t exceptions_per_area; + + /* + * Now that we have an asynchronous kcopyd there is no + * need for large chunk sizes, so it wont hurt to have a + * whole chunks worth of metadata in memory at once. + */ + void *area; + + /* + * An area of zeros used to clear the next area. + */ + void *zero_area; + + /* + * Used to keep track of which metadata area the data in + * 'chunk' refers to. + */ + chunk_t current_area; + + /* + * The next free chunk for an exception. + */ + chunk_t next_free; + + /* + * The index of next free exception in the current + * metadata area. + */ + uint32_t current_committed; + + atomic_t pending_count; + uint32_t callback_count; + struct commit_callback *callbacks; + struct dm_io_client *io_client; + + struct workqueue_struct *metadata_wq; +}; + +static unsigned sectors_to_pages(unsigned sectors) +{ + return DIV_ROUND_UP(sectors, PAGE_SIZE >> 9); +} + +static int alloc_area(struct pstore *ps) +{ + int r = -ENOMEM; + size_t len; + + len = ps->snap->chunk_size << SECTOR_SHIFT; + + /* + * Allocate the chunk_size block of memory that will hold + * a single metadata area. + */ + ps->area = vmalloc(len); + if (!ps->area) + return r; + + ps->zero_area = vmalloc(len); + if (!ps->zero_area) { + vfree(ps->area); + return r; + } + memset(ps->zero_area, 0, len); + + return 0; +} + +static void free_area(struct pstore *ps) +{ + vfree(ps->area); + ps->area = NULL; + vfree(ps->zero_area); + ps->zero_area = NULL; +} + +struct mdata_req { + struct dm_io_region *where; + struct dm_io_request *io_req; + struct work_struct work; + int result; +}; + +static void do_metadata(struct work_struct *work) +{ + struct mdata_req *req = container_of(work, struct mdata_req, work); + + req->result = dm_io(req->io_req, 1, req->where, NULL); +} + +/* + * Read or write a chunk aligned and sized block of data from a device. + */ +static int chunk_io(struct pstore *ps, chunk_t chunk, int rw, int metadata) +{ + struct dm_io_region where = { + .bdev = ps->snap->cow->bdev, + .sector = ps->snap->chunk_size * chunk, + .count = ps->snap->chunk_size, + }; + struct dm_io_request io_req = { + .bi_rw = rw, + .mem.type = DM_IO_VMA, + .mem.ptr.vma = ps->area, + .client = ps->io_client, + .notify.fn = NULL, + }; + struct mdata_req req; + + if (!metadata) + return dm_io(&io_req, 1, &where, NULL); + + req.where = &where; + req.io_req = &io_req; + + /* + * Issue the synchronous I/O from a different thread + * to avoid generic_make_request recursion. + */ + INIT_WORK(&req.work, do_metadata); + queue_work(ps->metadata_wq, &req.work); + flush_workqueue(ps->metadata_wq); + + return req.result; +} + +/* + * Convert a metadata area index to a chunk index. + */ +static chunk_t area_location(struct pstore *ps, chunk_t area) +{ + return 1 + ((ps->exceptions_per_area + 1) * area); +} + +/* + * Read or write a metadata area. Remembering to skip the first + * chunk which holds the header. + */ +static int area_io(struct pstore *ps, int rw) +{ + int r; + chunk_t chunk; + + chunk = area_location(ps, ps->current_area); + + r = chunk_io(ps, chunk, rw, 0); + if (r) + return r; + + return 0; +} + +static void zero_memory_area(struct pstore *ps) +{ + memset(ps->area, 0, ps->snap->chunk_size << SECTOR_SHIFT); +} + +static int zero_disk_area(struct pstore *ps, chunk_t area) +{ + struct dm_io_region where = { + .bdev = ps->snap->cow->bdev, + .sector = ps->snap->chunk_size * area_location(ps, area), + .count = ps->snap->chunk_size, + }; + struct dm_io_request io_req = { + .bi_rw = WRITE, + .mem.type = DM_IO_VMA, + .mem.ptr.vma = ps->zero_area, + .client = ps->io_client, + .notify.fn = NULL, + }; + + return dm_io(&io_req, 1, &where, NULL); +} + +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; + + /* + * 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; + } + + ps->io_client = dm_io_client_create(sectors_to_pages(ps->snap-> + chunk_size)); + if (IS_ERR(ps->io_client)) + return PTR_ERR(ps->io_client); + + r = alloc_area(ps); + if (r) + return r; + + r = chunk_io(ps, 0, READ, 1); + if (r) + goto bad; + + dh = (struct disk_header *) ps->area; + + if (le32_to_cpu(dh->magic) == 0) { + *new_snapshot = 1; + return 0; + } + + if (le32_to_cpu(dh->magic) != SNAP_MAGIC) { + DMWARN("Invalid or corrupt snapshot"); + r = -ENXIO; + goto bad; + } + + *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. */ + 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_client_resize(sectors_to_pages(ps->snap->chunk_size), + ps->io_client); + if (r) + return r; + + r = alloc_area(ps); + return r; + +bad: + free_area(ps); + return r; +} + +static int write_header(struct pstore *ps) +{ + struct disk_header *dh; + + memset(ps->area, 0, ps->snap->chunk_size << SECTOR_SHIFT); + + dh = (struct disk_header *) ps->area; + dh->magic = cpu_to_le32(SNAP_MAGIC); + dh->valid = cpu_to_le32(ps->valid); + dh->version = cpu_to_le32(ps->version); + dh->chunk_size = cpu_to_le32(ps->snap->chunk_size); + + return chunk_io(ps, 0, WRITE, 1); +} + +/* + * Access functions for the disk exceptions, these do the endian conversions. + */ +static struct disk_exception *get_exception(struct pstore *ps, uint32_t index) +{ + BUG_ON(index >= ps->exceptions_per_area); + + return ((struct disk_exception *) ps->area) + index; +} + +static void read_exception(struct pstore *ps, + uint32_t index, struct disk_exception *result) +{ + struct disk_exception *e = get_exception(ps, index); + + /* copy it */ + result->old_chunk = le64_to_cpu(e->old_chunk); + result->new_chunk = le64_to_cpu(e->new_chunk); +} + +static void write_exception(struct pstore *ps, + uint32_t index, struct disk_exception *de) +{ + struct disk_exception *e = get_exception(ps, index); + + /* copy it */ + e->old_chunk = cpu_to_le64(de->old_chunk); + e->new_chunk = cpu_to_le64(de->new_chunk); +} + +/* + * Registers the exceptions that are present in the current area. + * 'full' is filled in to indicate if the area has been + * filled. + */ +static int insert_exceptions(struct pstore *ps, int *full) +{ + int r; + unsigned int i; + struct disk_exception de; + + /* presume the area is full */ + *full = 1; + + for (i = 0; i < ps->exceptions_per_area; i++) { + read_exception(ps, i, &de); + + /* + * If the new_chunk is pointing at the start of + * the COW device, where the first metadata area + * is we know that we've hit the end of the + * exceptions. Therefore the area is not full. + */ + if (de.new_chunk == 0LL) { + ps->current_committed = i; + *full = 0; + break; + } + + /* + * Keep track of the start of the free chunks. + */ + if (ps->next_free <= de.new_chunk) + ps->next_free = de.new_chunk + 1; + + /* + * Otherwise we add the exception to the snapshot. + */ + r = dm_add_exception(ps->snap, de.old_chunk, de.new_chunk); + if (r) + return r; + } + + return 0; +} + +static int read_exceptions(struct pstore *ps) +{ + int r, full = 1; + + /* + * Keeping reading chunks and inserting exceptions until + * we find a partially full area. + */ + for (ps->current_area = 0; full; ps->current_area++) { + r = area_io(ps, READ); + if (r) + return r; + + r = insert_exceptions(ps, &full); + if (r) + return r; + } + + ps->current_area--; + + return 0; +} + +static struct pstore *get_info(struct dm_exception_store *store) +{ + return (struct pstore *) store->context; +} + +static void persistent_fraction_full(struct dm_exception_store *store, + sector_t *numerator, sector_t *denominator) +{ + *numerator = get_info(store)->next_free * store->snap->chunk_size; + *denominator = get_dev_size(store->snap->cow->bdev); +} + +static void persistent_destroy(struct dm_exception_store *store) +{ + struct pstore *ps = get_info(store); + + destroy_workqueue(ps->metadata_wq); + dm_io_client_destroy(ps->io_client); + vfree(ps->callbacks); + free_area(ps); + kfree(ps); +} + +static int persistent_read_metadata(struct dm_exception_store *store) +{ + int r, uninitialized_var(new_snapshot); + struct pstore *ps = get_info(store); + + /* + * Read the snapshot header. + */ + r = read_header(ps, &new_snapshot); + if (r) + return r; + + /* + * Now we know correct chunk_size, complete the initialisation. + */ + ps->exceptions_per_area = (ps->snap->chunk_size << SECTOR_SHIFT) / + sizeof(struct disk_exception); + ps->callbacks = dm_vcalloc(ps->exceptions_per_area, + sizeof(*ps->callbacks)); + if (!ps->callbacks) + return -ENOMEM; + + /* + * Do we need to setup a new snapshot ? + */ + if (new_snapshot) { + r = write_header(ps); + if (r) { + DMWARN("write_header failed"); + return r; + } + + ps->current_area = 0; + zero_memory_area(ps); + r = zero_disk_area(ps, 0); + if (r) { + DMWARN("zero_disk_area(0) failed"); + return r; + } + } else { + /* + * Sanity checks. + */ + if (ps->version != SNAPSHOT_DISK_VERSION) { + DMWARN("unable to handle snapshot disk version %d", + ps->version); + return -EINVAL; + } + + /* + * Metadata are valid, but snapshot is invalidated + */ + if (!ps->valid) + return 1; + + /* + * Read the metadata. + */ + r = read_exceptions(ps); + if (r) + return r; + } + + return 0; +} + +static int persistent_prepare(struct dm_exception_store *store, + struct dm_snap_exception *e) +{ + struct pstore *ps = get_info(store); + uint32_t stride; + chunk_t next_free; + sector_t size = get_dev_size(store->snap->cow->bdev); + + /* Is there enough room ? */ + if (size < ((ps->next_free + 1) * store->snap->chunk_size)) + return -ENOSPC; + + e->new_chunk = ps->next_free; + + /* + * Move onto the next free pending, making sure to take + * into account the location of the metadata chunks. + */ + stride = (ps->exceptions_per_area + 1); + next_free = ++ps->next_free; + if (sector_div(next_free, stride) == 1) + ps->next_free++; + + atomic_inc(&ps->pending_count); + return 0; +} + +static void persistent_commit(struct dm_exception_store *store, + struct dm_snap_exception *e, + void (*callback) (void *, int success), + void *callback_context) +{ + unsigned int i; + struct pstore *ps = get_info(store); + struct disk_exception de; + struct commit_callback *cb; + + de.old_chunk = e->old_chunk; + de.new_chunk = e->new_chunk; + write_exception(ps, ps->current_committed++, &de); + + /* + * Add the callback to the back of the array. This code + * is the only place where the callback array is + * manipulated, and we know that it will never be called + * multiple times concurrently. + */ + cb = ps->callbacks + ps->callback_count++; + cb->callback = callback; + cb->context = callback_context; + + /* + * If there are exceptions in flight and we have not yet + * filled this metadata area there's nothing more to do. + */ + if (!atomic_dec_and_test(&ps->pending_count) && + (ps->current_committed != ps->exceptions_per_area)) + return; + + /* + * If we completely filled the current area, then wipe the next one. + */ + if ((ps->current_committed == ps->exceptions_per_area) && + zero_disk_area(ps, ps->current_area + 1)) + ps->valid = 0; + + /* + * Commit exceptions to disk. + */ + if (ps->valid && area_io(ps, WRITE)) + ps->valid = 0; + + /* + * Advance to the next area if this one is full. + */ + if (ps->current_committed == ps->exceptions_per_area) { + ps->current_committed = 0; + ps->current_area++; + zero_memory_area(ps); + } + + for (i = 0; i < ps->callback_count; i++) { + cb = ps->callbacks + i; + cb->callback(cb->context, ps->valid); + } + + ps->callback_count = 0; +} + +static void persistent_drop(struct dm_exception_store *store) +{ + struct pstore *ps = get_info(store); + + ps->valid = 0; + if (write_header(ps)) + DMWARN("write header failed"); +} + +int dm_create_persistent(struct dm_exception_store *store) +{ + struct pstore *ps; + + /* allocate the pstore */ + ps = kmalloc(sizeof(*ps), GFP_KERNEL); + 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; + + ps->callback_count = 0; + atomic_set(&ps->pending_count, 0); + ps->callbacks = NULL; + + ps->metadata_wq = create_singlethread_workqueue("ksnaphd"); + if (!ps->metadata_wq) { + kfree(ps); + DMERR("couldn't start header metadata update thread"); + return -ENOMEM; + } + + store->destroy = persistent_destroy; + store->read_metadata = persistent_read_metadata; + store->prepare_exception = persistent_prepare; + store->commit_exception = persistent_commit; + store->drop_snapshot = persistent_drop; + store->fraction_full = persistent_fraction_full; + store->context = ps; + + return 0; +} + +int dm_persistent_snapshot_init(void) +{ + return 0; +} + +void dm_persistent_snapshot_exit(void) +{ +} diff --git a/drivers/md/dm-snap-transient.c b/drivers/md/dm-snap-transient.c new file mode 100644 index 00000000000..2a781df57fe --- /dev/null +++ b/drivers/md/dm-snap-transient.c @@ -0,0 +1,95 @@ +/* + * Copyright (C) 2001-2002 Sistina Software (UK) Limited. + * Copyright (C) 2006-2008 Red Hat GmbH + * + * This file is released under the GPL. + */ + +#include "dm-exception-store.h" +#include "dm-snap.h" + +#include <linux/mm.h> +#include <linux/pagemap.h> +#include <linux/vmalloc.h> +#include <linux/slab.h> +#include <linux/dm-io.h> + +#define DM_MSG_PREFIX "transient snapshot" + +/*----------------------------------------------------------------- + * Implementation of the store for non-persistent snapshots. + *---------------------------------------------------------------*/ +struct transient_c { + sector_t next_free; +}; + +static void transient_destroy(struct dm_exception_store *store) +{ + kfree(store->context); +} + +static int transient_read_metadata(struct dm_exception_store *store) +{ + return 0; +} + +static int transient_prepare(struct dm_exception_store *store, + struct dm_snap_exception *e) +{ + struct transient_c *tc = (struct transient_c *) store->context; + sector_t size = get_dev_size(store->snap->cow->bdev); + + if (size < (tc->next_free + store->snap->chunk_size)) + return -1; + + e->new_chunk = sector_to_chunk(store->snap, tc->next_free); + tc->next_free += store->snap->chunk_size; + + return 0; +} + +static void transient_commit(struct dm_exception_store *store, + struct dm_snap_exception *e, + void (*callback) (void *, int success), + void *callback_context) +{ + /* Just succeed */ + callback(callback_context, 1); +} + +static void transient_fraction_full(struct dm_exception_store *store, + sector_t *numerator, sector_t *denominator) +{ + *numerator = ((struct transient_c *) store->context)->next_free; + *denominator = get_dev_size(store->snap->cow->bdev); +} + +int dm_create_transient(struct dm_exception_store *store) +{ + struct transient_c *tc; + + 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; + + tc = kmalloc(sizeof(struct transient_c), GFP_KERNEL); + if (!tc) + return -ENOMEM; + + tc->next_free = 0; + store->context = tc; + + return 0; +} + +int dm_transient_snapshot_init(void) +{ + return 0; +} + +void dm_transient_snapshot_exit(void) +{ +} diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c index 81f03a0e783..018b567fc75 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -1406,6 +1406,12 @@ static int __init dm_snapshot_init(void) { int r; + r = dm_exception_store_init(); + if (r) { + DMERR("Failed to initialize exception stores"); + return r; + } + r = dm_register_target(&snapshot_target); if (r) { DMERR("snapshot target register failed %d", r); @@ -1454,17 +1460,17 @@ static int __init dm_snapshot_init(void) return 0; - bad_pending_pool: +bad_pending_pool: kmem_cache_destroy(tracked_chunk_cache); - bad5: +bad5: kmem_cache_destroy(pending_cache); - bad4: +bad4: kmem_cache_destroy(exception_cache); - bad3: +bad3: exit_origin_hash(); - bad2: +bad2: dm_unregister_target(&origin_target); - bad1: +bad1: dm_unregister_target(&snapshot_target); return r; } @@ -1480,6 +1486,8 @@ static void __exit dm_snapshot_exit(void) kmem_cache_destroy(pending_cache); kmem_cache_destroy(exception_cache); kmem_cache_destroy(tracked_chunk_cache); + + dm_exception_store_exit(); } /* Module hooks */ |