Release 4.7 drivers/md/dm-snap-persistent.c

/*
 * 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 <linux/ctype.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/vmalloc.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/dm-io.h>
#include "dm-bufio.h"


#define DM_MSG_PREFIX "persistent snapshot"

#define DM_CHUNK_SIZE_DEFAULT_SECTORS 32	
/* 16KB */


#define DM_PREFETCH_CHUNKS		12

/*-----------------------------------------------------------------
 * 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


#define NUM_SNAPSHOT_HDR_CHUNKS 1


struct disk_header {
	
__le32 magic;

	/*
         * Is this snapshot valid.  There is no way of recovering
         * an invalid snapshot.
         */
	
__le32 valid;

	/*
         * Simple, incrementing version. no backward
         * compatibility.
         */
	
__le32 version;

	/* In sectors */
	
__le32 chunk_size;
} 
__packed;


struct disk_exception {
	
__le64 old_chunk;
	
__le64 new_chunk;
} 
__packed;


struct core_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_exception_store *store;
	
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;

	/*
         * An area used for header. The header can be written
         * concurrently with metadata (when invalidating the snapshot),
         * so it needs a separate buffer.
         */
	
void *header_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.
         *
         * When creating exceptions, all the chunks here and above are
         * free.  It holds the next chunk to be allocated.  On rare
         * occasions (e.g. after a system crash) holes can be left in
         * the exception store because chunks can be committed out of
         * order.
         *
         * When merging exceptions, it does not necessarily mean all the
         * chunks here and above are free.  It holds the value it would
         * have held if all chunks had been committed in order of
         * allocation.  Consequently the value may occasionally be
         * slightly too low, but since it's only used for 'status' and
         * it can never reach its minimum value too early this doesn't
         * matter.
         */

	
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 int alloc_area(struct pstore *ps)
{
	int r = -ENOMEM;
	size_t len;

	len = ps->store->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)
		goto err_area;

	ps->zero_area = vzalloc(len);
	if (!ps->zero_area)
		goto err_zero_area;

	ps->header_area = vmalloc(len);
	if (!ps->header_area)
		goto err_header_area;

	return 0;

err_header_area:
	vfree(ps->zero_area);

err_zero_area:
	vfree(ps->area);

err_area:
	return r;
}

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41
35.96%
1
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jonathan brassow
jonathan brassow
2
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1
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joe perches
joe perches
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1
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static void free_area(struct pstore *ps)
{
	vfree(ps->area);
	ps->area = NULL;
	vfree(ps->zero_area);
	ps->zero_area = NULL;
	vfree(ps->header_area);
	ps->header_area = NULL;
}

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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);
}

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/*
 * Read or write a chunk aligned and sized block of data from a device.
 */


static int chunk_io(struct pstore *ps, void *area, chunk_t chunk, int rw,
		    int metadata)
{
	struct dm_io_region where = {
		.bdev = dm_snap_cow(ps->store->snap)->bdev,
		.sector = ps->store->chunk_size * chunk,
		.count = ps->store->chunk_size,
        };
	struct dm_io_request io_req = {
		.bi_rw = rw,
		.mem.type = DM_IO_VMA,
		.mem.ptr.vma = 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_ONSTACK(&req.work, do_metadata);
	queue_work(ps->metadata_wq, &req.work);
	flush_workqueue(ps->metadata_wq);
	destroy_work_on_stack(&req.work);

	return req.result;
}

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liu chuansheng
8
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mikulas patocka
mikulas patocka
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4.32%
2
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jonathan brassow
jonathan brassow
6
3.24%
2
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mike snitzer
mike snitzer
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2.16%
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andrew morton
andrew morton
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/*
 * Convert a metadata area index to a chunk index.
 */


static chunk_t area_location(struct pstore *ps, chunk_t area)
{
	return NUM_SNAPSHOT_HDR_CHUNKS + ((ps->exceptions_per_area + 1) * area);
}

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tomohiro kusumi
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static void skip_metadata(struct pstore *ps)
{
	uint32_t stride = ps->exceptions_per_area + 1;
	chunk_t next_free = ps->next_free;
	if (sector_div(next_free, stride) == NUM_SNAPSHOT_HDR_CHUNKS)
		ps->next_free++;
}

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/*
 * 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, ps->area, chunk, rw, 0);
	if (r)
		return r;

	return 0;
}

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static void zero_memory_area(struct pstore *ps)
{
	memset(ps->area, 0, ps->store->chunk_size << SECTOR_SHIFT);
}

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static int zero_disk_area(struct pstore *ps, chunk_t area)
{
	return chunk_io(ps, ps->zero_area, area_location(ps, area), WRITE, 0);
}

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mikulas patocka
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static int read_header(struct pstore *ps, int *new_snapshot)
{
	int r;
	struct disk_header *dh;
	unsigned chunk_size;
	int chunk_size_supplied = 1;
	char *chunk_err;

	/*
         * Use default chunk size (or logical_block_size, if larger)
         * if none supplied
         */
	if (!ps->store->chunk_size) {
		ps->store->chunk_size = max(DM_CHUNK_SIZE_DEFAULT_SECTORS,
		    bdev_logical_block_size(dm_snap_cow(ps->store->snap)->
					    bdev) >> 9);
		ps->store->chunk_mask = ps->store->chunk_size - 1;
		ps->store->chunk_shift = __ffs(ps->store->chunk_size);
		chunk_size_supplied = 0;
	}

	ps->io_client = dm_io_client_create();
	if (IS_ERR(ps->io_client))
		return PTR_ERR(ps->io_client);

	r = alloc_area(ps);
	if (r)
		return r;

	r = chunk_io(ps, ps->header_area, 0, READ, 1);
	if (r)
		goto bad;

	dh = ps->header_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 (ps->store->chunk_size == chunk_size)
		return 0;

	if (chunk_size_supplied)
		DMWARN("chunk size %u in device metadata overrides "
		       "table chunk size of %u.",
		       chunk_size, ps->store->chunk_size);

	/* We had a bogus chunk_size. Fix stuff up. */
	free_area(ps);

	r = dm_exception_store_set_chunk_size(ps->store, chunk_size,
					      &chunk_err);
	if (r) {
		DMERR("invalid on-disk chunk size %u: %s.",
		      chunk_size, chunk_err);
		return r;
	}

	r = alloc_area(ps);
	return r;

bad:
	free_area(ps);
	return r;
}

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alasdair kergon
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9.09%
mikulas patocka
mikulas patocka
41
11.82%
6
54.55%
jonathan brassow
jonathan brassow
19
5.48%
2
18.18%
mike snitzer
mike snitzer
4
1.15%
1
9.09%
martin k. petersen
martin k. petersen
1
0.29%
1
9.09%
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347
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11
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static int write_header(struct pstore *ps)
{
	struct disk_header *dh;

	memset(ps->header_area, 0, ps->store->chunk_size << SECTOR_SHIFT);

	dh = ps->header_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->store->chunk_size);

	return chunk_io(ps, ps->header_area, 0, WRITE, 1);
}

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mikulas patocka
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jonathan brassow
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/*
 * Access functions for the disk exceptions, these do the endian conversions.
 */


static struct disk_exception *get_exception(struct pstore *ps, void *ps_area,
					    uint32_t index)
{
	BUG_ON(index >= ps->exceptions_per_area);

	return ((struct disk_exception *) ps_area) + index;
}

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static void read_exception(struct pstore *ps, void *ps_area,
			   uint32_t index, struct core_exception *result)
{
	struct disk_exception *de = get_exception(ps, ps_area, index);

	/* copy it */
	result->old_chunk = le64_to_cpu(de->old_chunk);
	result->new_chunk = le64_to_cpu(de->new_chunk);
}

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static void write_exception(struct pstore *ps,
			    uint32_t index, struct core_exception *e)
{
	struct disk_exception *de = get_exception(ps, ps->area, index);

	/* copy it */
	de->old_chunk = cpu_to_le64(e->old_chunk);
	de->new_chunk = cpu_to_le64(e->new_chunk);
}

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mikulas patocka
4
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static void clear_exception(struct pstore *ps, uint32_t index)
{
	struct disk_exception *de = get_exception(ps, ps->area, index);

	/* clear it */
	de->old_chunk = 0;
	de->new_chunk = 0;
}

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mikulas patocka
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/*
 * 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, void *ps_area,
			     int (*callback)(void *callback_context,
					     chunk_t old, chunk_t new),
			     void *callback_context,
			     int *full)
{
	int r;
	unsigned int i;
	struct core_exception e;

	/* presume the area is full */
	*full = 1;

	for (i = 0; i < ps->exceptions_per_area; i++) {
		read_exception(ps, ps_area, i, &e);

		/*
                 * 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 (e.new_chunk == 0LL) {
			ps->current_committed = i;
			*full = 0;
			break;
		}

		/*
                 * Keep track of the start of the free chunks.
                 */
		if (ps->next_free <= e.new_chunk)
			ps->next_free = e.new_chunk + 1;

		/*
                 * Otherwise we add the exception to the snapshot.
                 */
		r = callback(callback_context, e.old_chunk, e.new_chunk);
		if (r)
			return r;
	}

	return 0;
}

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23
14.74%
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mikulas patocka
mikulas patocka
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3.85%
1
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static int read_exceptions(struct pstore *ps,
			   int (*callback)(void *callback_context, chunk_t old,
					   chunk_t new),
			   void *callback_context)
{
	int r, full = 1;
	struct dm_bufio_client *client;
	chunk_t prefetch_area = 0;

	client = dm_bufio_client_create(dm_snap_cow(ps->store->snap)->bdev,
					ps->store->chunk_size << SECTOR_SHIFT,
					1, 0, NULL, NULL);

	if (IS_ERR(client))
		return PTR_ERR(client);

	/*
         * Setup for one current buffer + desired readahead buffers.
         */
	dm_bufio_set_minimum_buffers(client, 1 + DM_PREFETCH_CHUNKS);

	/*
         * Keeping reading chunks and inserting exceptions until
         * we find a partially full area.
         */
	for (ps->current_area = 0; full; ps->current_area++) {
		struct dm_buffer *bp;
		void *area;
		chunk_t chunk;

		if (unlikely(prefetch_area < ps->current_area))
			prefetch_area = ps->current_area;

		if (DM_PREFETCH_CHUNKS) do {
			chunk_t pf_chunk = area_location(ps, prefetch_area);
			if (unlikely(pf_chunk >= dm_bufio_get_device_size(client)))
				break;
			dm_bufio_prefetch(client, pf_chunk, 1);
			prefetch_area++;
			if (unlikely(!prefetch_area))
				break;
		} while (prefetch_area <= ps->current_area + DM_PREFETCH_CHUNKS);

		chunk = area_location(ps, ps->current_area);

		area = dm_bufio_read(client, chunk, &bp);
		if (IS_ERR(area)) {
			r = PTR_ERR(area);
			goto ret_destroy_bufio;
		}

		r = insert_exceptions(ps, area, callback, callback_context,
				      &full);

		if (!full)
			memcpy(ps->area, area, ps->store->chunk_size << SECTOR_SHIFT);

		dm_bufio_release(bp);

		dm_bufio_forget(client, chunk);

		if (unlikely(r))
			goto ret_destroy_bufio;
	}

	ps->current_area--;

	skip_metadata(ps);

	r = 0;

ret_destroy_bufio:
	dm_bufio_client_destroy(client);

	return r;
}

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71.43%
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jonathan brassow
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static struct pstore *get_info(struct dm_exception_store *store)
{
	return (struct pstore *) store->context;
}

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static void persistent_usage(struct dm_exception_store *store,
			     sector_t *total_sectors,
			     sector_t *sectors_allocated,
			     sector_t *metadata_sectors)
{
	struct pstore *ps = get_info(store);

	*sectors_allocated = ps->next_free * store->chunk_size;
	*total_sectors = get_dev_size(dm_snap_cow(store->snap)->bdev);

	/*
         * First chunk is the fixed header.
         * Then there are (ps->current_area + 1) metadata chunks, each one
         * separated from the next by ps->exceptions_per_area data chunks.
         */
	*metadata_sectors = (ps->current_area + 1 + NUM_SNAPSHOT_HDR_CHUNKS) *
			    store->chunk_size;
}

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mike snitzer
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2
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mikulas patocka
mikulas patocka
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static void persistent_dtr(struct dm_exception_store *store)
{
	struct pstore *ps = get_info(store);

	destroy_workqueue(ps->metadata_wq);

	/* Created in read_header */
	if (ps->io_client)
		dm_io_client_destroy(ps->io_client);
	free_area(ps);

	/* Allocated in persistent_read_metadata */
	vfree(ps->callbacks);

	kfree(ps);
}

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static int persistent_read_metadata(struct dm_exception_store *store,
				    int (*callback)(void *callback_context,
						    chunk_t old, chunk_t new),
				    void *callback_context)
{
	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->store->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;
	}
	/*
         * 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, callback, callback_context);

	return r;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
alasdair kergon
alasdair kergon
199
86.90%
1
25.00%
jonathan brassow
jonathan brassow
30
13.10%
3
75.00%
Total
229
100.00%
4
100.00%



static int persistent_prepare_exception(struct dm_exception_store *store,
					struct dm_exception *e)
{
	struct pstore *ps = get_info(store);
	sector_t size = get_dev_size(dm_snap_cow(store->snap)->bdev);

	/* Is there enough room ? */
	if (size < ((ps->next_free + 1) * store->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.
         */
	ps->next_free++;
	skip_metadata(ps);

	atomic_inc(&ps->pending_count);
	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
alasdair kergon
alasdair kergon
86
91.49%
1
20.00%
mike snitzer
mike snitzer
4
4.26%
1
20.00%
jonathan brassow
jonathan brassow
2
2.13%
2
40.00%
mikulas patocka
mikulas patocka
2
2.13%
1
20.00%
Total
94
100.00%
5
100.00%



static void persistent_commit_exception(struct dm_exception_store *store,
					struct dm_exception *e, int valid,
					void (*callback) (void *, int success),
					void *callback_context)
{
	unsigned int i;
	struct pstore *ps = get_info(store);
	struct core_exception ce;
	struct commit_callback *cb;

	if (!valid)
		ps->valid = 0;

	ce.old_chunk = e->old_chunk;
	ce.new_chunk = e->new_chunk;
	write_exception(ps, ps->current_committed++, &ce);

	/*
         * 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_FLUSH_FUA))
		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;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
alasdair kergon
alasdair kergon
252
93.68%
2
33.33%
mikulas patocka
mikulas patocka
14
5.20%
1
16.67%
jonathan brassow
jonathan brassow
2
0.74%
2
33.33%
tejun heo
tejun heo
1
0.37%
1
16.67%
Total
269
100.00%
6
100.00%



static int persistent_prepare_merge(struct dm_exception_store *store,
				    chunk_t *last_old_chunk,
				    chunk_t *last_new_chunk)
{
	struct pstore *ps = get_info(store);
	struct core_exception ce;
	int nr_consecutive;
	int r;

	/*
         * When current area is empty, move back to preceding area.
         */
	if (!ps->current_committed) {
		/*
                 * Have we finished?
                 */
		if (!ps->current_area)
			return 0;

		ps->current_area--;
		r = area_io(ps, READ);
		if (r < 0)
			return r;
		ps->current_committed = ps->exceptions_per_area;
	}

	read_exception(ps, ps->area, ps->current_committed - 1, &ce);
	*last_old_chunk = ce.old_chunk;
	*last_new_chunk = ce.new_chunk;

	/*
         * Find number of consecutive chunks within the current area,
         * working backwards.
         */
	for (nr_consecutive = 1; nr_consecutive < ps->current_committed;
	     nr_consecutive++) {
		read_exception(ps, ps->area,
			       ps->current_committed - 1 - nr_consecutive, &ce);
		if (ce.old_chunk != *last_old_chunk - nr_consecutive ||
		    ce.new_chunk != *last_new_chunk - nr_consecutive)
			break;
	}

	return nr_consecutive;
}

Contributors
Person
Tokens
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Commits
CommitProp
mikulas patocka
mikulas patocka
177
95.68%
2
66.67%
alasdair kergon
alasdair kergon
8
4.32%
1
33.33%
Total
185
100.00%
3
100.00%



static int persistent_commit_merge(struct dm_exception_store *store,
				   int nr_merged)
{
	int r, i;
	struct pstore *ps = get_info(store);

	BUG_ON(nr_merged > ps->current_committed);

	for (i = 0; i < nr_merged; i++)
		clear_exception(ps, ps->current_committed - 1 - i);

	r = area_io(ps, WRITE_FLUSH_FUA);
	if (r < 0)
		return r;

	ps->current_committed -= nr_merged;

	/*
         * At this stage, only persistent_usage() uses ps->next_free, so
         * we make no attempt to keep ps->next_free strictly accurate
         * as exceptions may have been committed out-of-order originally.
         * Once a snapshot has become merging, we set it to the value it
         * would have held had all the exceptions been committed in order.
         *
         * ps->current_area does not get reduced by prepare_merge() until
         * after commit_merge() has removed the nr_merged previous exceptions.
         */
	ps->next_free = area_location(ps, ps->current_area) +
			ps->current_committed + 1;

	return 0;
}

Contributors
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CommitProp
mikulas patocka
mikulas patocka
111
100.00%
2
100.00%
Total
111
100.00%
2
100.00%



static void persistent_drop_snapshot(struct dm_exception_store *store)
{
	struct pstore *ps = get_info(store);

	ps->valid = 0;
	if (write_header(ps))
		DMWARN("write header failed");
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
alasdair kergon
alasdair kergon
38
97.44%
1
50.00%
jonathan brassow
jonathan brassow
1
2.56%
1
50.00%
Total
39
100.00%
2
100.00%



static int persistent_ctr(struct dm_exception_store *store, char *options)
{
	struct pstore *ps;
	int r;

	/* allocate the pstore */
	ps = kzalloc(sizeof(*ps), GFP_KERNEL);
	if (!ps)
		return -ENOMEM;

	ps->store = store;
	ps->valid = 1;
	ps->version = SNAPSHOT_DISK_VERSION;
	ps->area = NULL;
	ps->zero_area = NULL;
	ps->header_area = NULL;
	ps->next_free = NUM_SNAPSHOT_HDR_CHUNKS + 1; /* header and 1st area */
	ps->current_committed = 0;

	ps->callback_count = 0;
	atomic_set(&ps->pending_count, 0);
	ps->callbacks = NULL;

	ps->metadata_wq = alloc_workqueue("ksnaphd", WQ_MEM_RECLAIM, 0);
	if (!ps->metadata_wq) {
		DMERR("couldn't start header metadata update thread");
		r = -ENOMEM;
		goto err_workqueue;
	}

	if (options) {
		char overflow = toupper(options[0]);
		if (overflow == 'O')
			store->userspace_supports_overflow = true;
		else {
			DMERR("Unsupported persistent store option: %s", options);
			r = -EINVAL;
			goto err_options;
		}
	}

	store->context = ps;

	return 0;

err_options:
	destroy_workqueue(ps->metadata_wq);
err_workqueue:
	kfree(ps);

	return r;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
alasdair kergon
alasdair kergon
119
51.97%
1
10.00%
mike snitzer
mike snitzer
42
18.34%
1
10.00%
sudip mukherjee
sudip mukherjee
34
14.85%
1
10.00%
mikulas patocka
mikulas patocka
16
6.99%
2
20.00%
jonathan brassow
jonathan brassow
13
5.68%
3
30.00%
tejun heo
tejun heo
5
2.18%
2
20.00%
Total
229
100.00%
10
100.00%



static unsigned persistent_status(struct dm_exception_store *store,
				  status_type_t status, char *result,
				  unsigned maxlen)
{
	unsigned sz = 0;

	switch (status) {
	case STATUSTYPE_INFO:
		break;
	case STATUSTYPE_TABLE:
		DMEMIT(" %s %llu", store->userspace_supports_overflow ? "PO" : "P",
		       (unsigned long long)store->chunk_size);
	}

	return sz;
}

Contributors
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CommitProp
jonathan brassow
jonathan brassow
54
84.38%
2
50.00%
mike snitzer
mike snitzer
9
14.06%
1
25.00%
alasdair kergon
alasdair kergon
1
1.56%
1
25.00%
Total
64
100.00%
4
100.00%


static struct dm_exception_store_type _persistent_type = {
	.name = "persistent",
	.module = THIS_MODULE,
	.ctr = persistent_ctr,
	.dtr = persistent_dtr,
	.read_metadata = persistent_read_metadata,
	.prepare_exception = persistent_prepare_exception,
	.commit_exception = persistent_commit_exception,
	.prepare_merge = persistent_prepare_merge,
	.commit_merge = persistent_commit_merge,
	.drop_snapshot = persistent_drop_snapshot,
	.usage = persistent_usage,
	.status = persistent_status,
};


static struct dm_exception_store_type _persistent_compat_type = {
	.name = "P",
	.module = THIS_MODULE,
	.ctr = persistent_ctr,
	.dtr = persistent_dtr,
	.read_metadata = persistent_read_metadata,
	.prepare_exception = persistent_prepare_exception,
	.commit_exception = persistent_commit_exception,
	.prepare_merge = persistent_prepare_merge,
	.commit_merge = persistent_commit_merge,
	.drop_snapshot = persistent_drop_snapshot,
	.usage = persistent_usage,
	.status = persistent_status,
};



int dm_persistent_snapshot_init(void)
{
	int r;

	r = dm_exception_store_type_register(&_persistent_type);
	if (r) {
		DMERR("Unable to register persistent exception store type");
		return r;
	}

	r = dm_exception_store_type_register(&_persistent_compat_type);
	if (r) {
		DMERR("Unable to register old-style persistent exception "
		      "store type");
		dm_exception_store_type_unregister(&_persistent_type);
		return r;
	}

	return r;
}

Contributors
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jonathan brassow
jonathan brassow
55
85.94%
1
50.00%
alasdair kergon
alasdair kergon
9
14.06%
1
50.00%
Total
64
100.00%
2
100.00%



void dm_persistent_snapshot_exit(void)
{
	dm_exception_store_type_unregister(&_persistent_type);
	dm_exception_store_type_unregister(&_persistent_compat_type);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
jonathan brassow
jonathan brassow
14
73.68%
1
50.00%
alasdair kergon
alasdair kergon
5
26.32%
1
50.00%
Total
19
100.00%
2
100.00%

Overall Contributors
Person
Tokens
Prop
Commits
CommitProp
alasdair kergon
alasdair kergon
2184
61.61%
2
5.00%
mikulas patocka
mikulas patocka
833
23.50%
15
37.50%
jonathan brassow
jonathan brassow
366
10.32%
10
25.00%
mike snitzer
mike snitzer
107
3.02%
3
7.50%
sudip mukherjee
sudip mukherjee
34
0.96%
1
2.50%
liu chuansheng
liu chuansheng
8
0.23%
1
2.50%
tejun heo
tejun heo
6
0.17%
3
7.50%
paul gortmaker
paul gortmaker
3
0.08%
1
2.50%
martin k. petersen
martin k. petersen
1
0.03%
1
2.50%
andrew morton
andrew morton
1
0.03%
1
2.50%
tomohiro kusumi
tomohiro kusumi
1
0.03%
1
2.50%
joe perches
joe perches
1
0.03%
1
2.50%
Total
3545
100.00%
40
100.00%
  
Directory: drivers/md

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