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![Jan Kara](/assets/img/avatar_default.png)
Commitb685d3d65a
("block: treat REQ_FUA and REQ_PREFLUSH as synchronous") removed REQ_SYNC flag from WRITE_{FUA|PREFLUSH|...} definitions. generic_make_request_checks() however strips REQ_FUA and REQ_PREFLUSH flags from a bio when the storage doesn't report volatile write cache and thus write effectively becomes asynchronous which can lead to performance regressions. Fix the problem by making sure all bios which are synchronous are properly marked with REQ_SYNC. Fixes:b685d3d65a
("block: treat REQ_FUA and REQ_PREFLUSH as synchronous") Cc: stable@vger.kernel.org Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
978 lines
23 KiB
C
978 lines
23 KiB
C
/*
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* Copyright (C) 2001-2002 Sistina Software (UK) Limited.
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* Copyright (C) 2006-2008 Red Hat GmbH
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*
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* This file is released under the GPL.
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*/
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#include "dm-exception-store.h"
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#include <linux/ctype.h>
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#include <linux/mm.h>
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#include <linux/pagemap.h>
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#include <linux/vmalloc.h>
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#include <linux/export.h>
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#include <linux/slab.h>
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#include <linux/dm-io.h>
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#include "dm-bufio.h"
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#define DM_MSG_PREFIX "persistent snapshot"
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#define DM_CHUNK_SIZE_DEFAULT_SECTORS 32 /* 16KB */
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#define DM_PREFETCH_CHUNKS 12
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/*-----------------------------------------------------------------
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* Persistent snapshots, by persistent we mean that the snapshot
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* will survive a reboot.
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*---------------------------------------------------------------*/
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/*
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* We need to store a record of which parts of the origin have
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* been copied to the snapshot device. The snapshot code
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* requires that we copy exception chunks to chunk aligned areas
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* of the COW store. It makes sense therefore, to store the
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* metadata in chunk size blocks.
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*
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* There is no backward or forward compatibility implemented,
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* snapshots with different disk versions than the kernel will
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* not be usable. It is expected that "lvcreate" will blank out
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* the start of a fresh COW device before calling the snapshot
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* constructor.
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*
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* The first chunk of the COW device just contains the header.
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* After this there is a chunk filled with exception metadata,
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* followed by as many exception chunks as can fit in the
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* metadata areas.
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*
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* All on disk structures are in little-endian format. The end
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* of the exceptions info is indicated by an exception with a
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* new_chunk of 0, which is invalid since it would point to the
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* header chunk.
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*/
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/*
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* Magic for persistent snapshots: "SnAp" - Feeble isn't it.
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*/
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#define SNAP_MAGIC 0x70416e53
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/*
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* The on-disk version of the metadata.
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*/
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#define SNAPSHOT_DISK_VERSION 1
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#define NUM_SNAPSHOT_HDR_CHUNKS 1
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struct disk_header {
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__le32 magic;
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/*
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* Is this snapshot valid. There is no way of recovering
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* an invalid snapshot.
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*/
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__le32 valid;
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/*
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* Simple, incrementing version. no backward
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* compatibility.
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*/
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__le32 version;
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/* In sectors */
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__le32 chunk_size;
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} __packed;
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struct disk_exception {
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__le64 old_chunk;
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__le64 new_chunk;
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} __packed;
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struct core_exception {
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uint64_t old_chunk;
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uint64_t new_chunk;
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};
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struct commit_callback {
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void (*callback)(void *, int success);
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void *context;
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};
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/*
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* The top level structure for a persistent exception store.
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*/
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struct pstore {
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struct dm_exception_store *store;
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int version;
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int valid;
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uint32_t exceptions_per_area;
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/*
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* Now that we have an asynchronous kcopyd there is no
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* need for large chunk sizes, so it wont hurt to have a
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* whole chunks worth of metadata in memory at once.
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*/
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void *area;
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/*
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* An area of zeros used to clear the next area.
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*/
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void *zero_area;
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/*
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* An area used for header. The header can be written
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* concurrently with metadata (when invalidating the snapshot),
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* so it needs a separate buffer.
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*/
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void *header_area;
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/*
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* Used to keep track of which metadata area the data in
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* 'chunk' refers to.
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*/
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chunk_t current_area;
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/*
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* The next free chunk for an exception.
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*
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* When creating exceptions, all the chunks here and above are
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* free. It holds the next chunk to be allocated. On rare
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* occasions (e.g. after a system crash) holes can be left in
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* the exception store because chunks can be committed out of
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* order.
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*
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* When merging exceptions, it does not necessarily mean all the
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* chunks here and above are free. It holds the value it would
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* have held if all chunks had been committed in order of
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* allocation. Consequently the value may occasionally be
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* slightly too low, but since it's only used for 'status' and
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* it can never reach its minimum value too early this doesn't
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* matter.
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*/
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chunk_t next_free;
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/*
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* The index of next free exception in the current
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* metadata area.
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*/
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uint32_t current_committed;
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atomic_t pending_count;
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uint32_t callback_count;
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struct commit_callback *callbacks;
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struct dm_io_client *io_client;
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struct workqueue_struct *metadata_wq;
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};
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static int alloc_area(struct pstore *ps)
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{
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int r = -ENOMEM;
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size_t len;
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len = ps->store->chunk_size << SECTOR_SHIFT;
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/*
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* Allocate the chunk_size block of memory that will hold
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* a single metadata area.
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*/
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ps->area = vmalloc(len);
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if (!ps->area)
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goto err_area;
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ps->zero_area = vzalloc(len);
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if (!ps->zero_area)
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goto err_zero_area;
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ps->header_area = vmalloc(len);
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if (!ps->header_area)
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goto err_header_area;
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return 0;
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err_header_area:
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vfree(ps->zero_area);
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err_zero_area:
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vfree(ps->area);
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err_area:
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return r;
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}
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static void free_area(struct pstore *ps)
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{
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vfree(ps->area);
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ps->area = NULL;
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vfree(ps->zero_area);
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ps->zero_area = NULL;
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vfree(ps->header_area);
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ps->header_area = NULL;
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}
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struct mdata_req {
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struct dm_io_region *where;
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struct dm_io_request *io_req;
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struct work_struct work;
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int result;
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};
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static void do_metadata(struct work_struct *work)
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{
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struct mdata_req *req = container_of(work, struct mdata_req, work);
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req->result = dm_io(req->io_req, 1, req->where, NULL);
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}
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/*
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* Read or write a chunk aligned and sized block of data from a device.
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*/
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static int chunk_io(struct pstore *ps, void *area, chunk_t chunk, int op,
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int op_flags, int metadata)
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{
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struct dm_io_region where = {
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.bdev = dm_snap_cow(ps->store->snap)->bdev,
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.sector = ps->store->chunk_size * chunk,
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.count = ps->store->chunk_size,
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};
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struct dm_io_request io_req = {
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.bi_op = op,
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.bi_op_flags = op_flags,
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.mem.type = DM_IO_VMA,
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.mem.ptr.vma = area,
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.client = ps->io_client,
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.notify.fn = NULL,
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};
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struct mdata_req req;
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if (!metadata)
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return dm_io(&io_req, 1, &where, NULL);
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req.where = &where;
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req.io_req = &io_req;
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/*
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* Issue the synchronous I/O from a different thread
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* to avoid generic_make_request recursion.
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*/
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INIT_WORK_ONSTACK(&req.work, do_metadata);
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queue_work(ps->metadata_wq, &req.work);
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flush_workqueue(ps->metadata_wq);
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destroy_work_on_stack(&req.work);
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return req.result;
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}
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/*
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* Convert a metadata area index to a chunk index.
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*/
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static chunk_t area_location(struct pstore *ps, chunk_t area)
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{
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return NUM_SNAPSHOT_HDR_CHUNKS + ((ps->exceptions_per_area + 1) * area);
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}
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static void skip_metadata(struct pstore *ps)
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{
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uint32_t stride = ps->exceptions_per_area + 1;
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chunk_t next_free = ps->next_free;
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if (sector_div(next_free, stride) == NUM_SNAPSHOT_HDR_CHUNKS)
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ps->next_free++;
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}
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/*
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* Read or write a metadata area. Remembering to skip the first
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* chunk which holds the header.
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*/
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static int area_io(struct pstore *ps, int op, int op_flags)
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{
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int r;
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chunk_t chunk;
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chunk = area_location(ps, ps->current_area);
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r = chunk_io(ps, ps->area, chunk, op, op_flags, 0);
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if (r)
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return r;
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return 0;
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}
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static void zero_memory_area(struct pstore *ps)
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{
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memset(ps->area, 0, ps->store->chunk_size << SECTOR_SHIFT);
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}
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static int zero_disk_area(struct pstore *ps, chunk_t area)
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{
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return chunk_io(ps, ps->zero_area, area_location(ps, area),
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REQ_OP_WRITE, 0, 0);
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}
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static int read_header(struct pstore *ps, int *new_snapshot)
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{
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int r;
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struct disk_header *dh;
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unsigned chunk_size;
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int chunk_size_supplied = 1;
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char *chunk_err;
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/*
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* Use default chunk size (or logical_block_size, if larger)
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* if none supplied
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*/
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if (!ps->store->chunk_size) {
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ps->store->chunk_size = max(DM_CHUNK_SIZE_DEFAULT_SECTORS,
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bdev_logical_block_size(dm_snap_cow(ps->store->snap)->
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bdev) >> 9);
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ps->store->chunk_mask = ps->store->chunk_size - 1;
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ps->store->chunk_shift = __ffs(ps->store->chunk_size);
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chunk_size_supplied = 0;
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}
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ps->io_client = dm_io_client_create();
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if (IS_ERR(ps->io_client))
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return PTR_ERR(ps->io_client);
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r = alloc_area(ps);
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if (r)
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return r;
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r = chunk_io(ps, ps->header_area, 0, REQ_OP_READ, 0, 1);
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if (r)
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goto bad;
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dh = ps->header_area;
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if (le32_to_cpu(dh->magic) == 0) {
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*new_snapshot = 1;
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return 0;
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}
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if (le32_to_cpu(dh->magic) != SNAP_MAGIC) {
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DMWARN("Invalid or corrupt snapshot");
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r = -ENXIO;
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goto bad;
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}
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*new_snapshot = 0;
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ps->valid = le32_to_cpu(dh->valid);
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ps->version = le32_to_cpu(dh->version);
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chunk_size = le32_to_cpu(dh->chunk_size);
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if (ps->store->chunk_size == chunk_size)
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return 0;
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if (chunk_size_supplied)
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DMWARN("chunk size %u in device metadata overrides "
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"table chunk size of %u.",
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chunk_size, ps->store->chunk_size);
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/* We had a bogus chunk_size. Fix stuff up. */
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free_area(ps);
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r = dm_exception_store_set_chunk_size(ps->store, chunk_size,
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&chunk_err);
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if (r) {
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DMERR("invalid on-disk chunk size %u: %s.",
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chunk_size, chunk_err);
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return r;
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}
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r = alloc_area(ps);
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return r;
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bad:
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free_area(ps);
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return r;
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}
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static int write_header(struct pstore *ps)
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{
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struct disk_header *dh;
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memset(ps->header_area, 0, ps->store->chunk_size << SECTOR_SHIFT);
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dh = ps->header_area;
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dh->magic = cpu_to_le32(SNAP_MAGIC);
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dh->valid = cpu_to_le32(ps->valid);
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dh->version = cpu_to_le32(ps->version);
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dh->chunk_size = cpu_to_le32(ps->store->chunk_size);
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return chunk_io(ps, ps->header_area, 0, REQ_OP_WRITE, 0, 1);
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}
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/*
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* Access functions for the disk exceptions, these do the endian conversions.
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*/
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static struct disk_exception *get_exception(struct pstore *ps, void *ps_area,
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uint32_t index)
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{
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BUG_ON(index >= ps->exceptions_per_area);
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return ((struct disk_exception *) ps_area) + index;
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}
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static void read_exception(struct pstore *ps, void *ps_area,
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uint32_t index, struct core_exception *result)
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{
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struct disk_exception *de = get_exception(ps, ps_area, index);
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/* copy it */
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result->old_chunk = le64_to_cpu(de->old_chunk);
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result->new_chunk = le64_to_cpu(de->new_chunk);
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}
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static void write_exception(struct pstore *ps,
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uint32_t index, struct core_exception *e)
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{
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struct disk_exception *de = get_exception(ps, ps->area, index);
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/* copy it */
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de->old_chunk = cpu_to_le64(e->old_chunk);
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de->new_chunk = cpu_to_le64(e->new_chunk);
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}
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static void clear_exception(struct pstore *ps, uint32_t index)
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{
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struct disk_exception *de = get_exception(ps, ps->area, index);
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/* clear it */
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de->old_chunk = 0;
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de->new_chunk = 0;
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}
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/*
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* Registers the exceptions that are present in the current area.
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* 'full' is filled in to indicate if the area has been
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* filled.
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*/
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static int insert_exceptions(struct pstore *ps, void *ps_area,
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int (*callback)(void *callback_context,
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chunk_t old, chunk_t new),
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void *callback_context,
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int *full)
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{
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int r;
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unsigned int i;
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struct core_exception e;
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/* presume the area is full */
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*full = 1;
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for (i = 0; i < ps->exceptions_per_area; i++) {
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read_exception(ps, ps_area, i, &e);
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/*
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* If the new_chunk is pointing at the start of
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* the COW device, where the first metadata area
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* is we know that we've hit the end of the
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* exceptions. Therefore the area is not full.
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*/
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if (e.new_chunk == 0LL) {
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ps->current_committed = i;
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*full = 0;
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break;
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}
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/*
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* Keep track of the start of the free chunks.
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*/
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if (ps->next_free <= e.new_chunk)
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ps->next_free = e.new_chunk + 1;
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/*
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* Otherwise we add the exception to the snapshot.
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*/
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r = callback(callback_context, e.old_chunk, e.new_chunk);
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if (r)
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return r;
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}
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return 0;
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}
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static int read_exceptions(struct pstore *ps,
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int (*callback)(void *callback_context, chunk_t old,
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chunk_t new),
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void *callback_context)
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{
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int r, full = 1;
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struct dm_bufio_client *client;
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chunk_t prefetch_area = 0;
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client = dm_bufio_client_create(dm_snap_cow(ps->store->snap)->bdev,
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ps->store->chunk_size << SECTOR_SHIFT,
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1, 0, NULL, NULL);
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if (IS_ERR(client))
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return PTR_ERR(client);
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/*
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* Setup for one current buffer + desired readahead buffers.
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*/
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dm_bufio_set_minimum_buffers(client, 1 + DM_PREFETCH_CHUNKS);
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/*
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* Keeping reading chunks and inserting exceptions until
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* we find a partially full area.
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*/
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for (ps->current_area = 0; full; ps->current_area++) {
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struct dm_buffer *bp;
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void *area;
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chunk_t chunk;
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if (unlikely(prefetch_area < ps->current_area))
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prefetch_area = ps->current_area;
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if (DM_PREFETCH_CHUNKS) do {
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chunk_t pf_chunk = area_location(ps, prefetch_area);
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if (unlikely(pf_chunk >= dm_bufio_get_device_size(client)))
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break;
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dm_bufio_prefetch(client, pf_chunk, 1);
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prefetch_area++;
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if (unlikely(!prefetch_area))
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break;
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} while (prefetch_area <= ps->current_area + DM_PREFETCH_CHUNKS);
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chunk = area_location(ps, ps->current_area);
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area = dm_bufio_read(client, chunk, &bp);
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if (IS_ERR(area)) {
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r = PTR_ERR(area);
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goto ret_destroy_bufio;
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}
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|
|
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;
|
|
}
|
|
|
|
static struct pstore *get_info(struct dm_exception_store *store)
|
|
{
|
|
return (struct pstore *) store->context;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
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);
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
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, REQ_OP_WRITE,
|
|
REQ_PREFLUSH | REQ_FUA | REQ_SYNC))
|
|
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 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, REQ_OP_READ, 0);
|
|
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;
|
|
}
|
|
|
|
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, REQ_OP_WRITE, REQ_PREFLUSH | REQ_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;
|
|
}
|
|
|
|
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");
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
void dm_persistent_snapshot_exit(void)
|
|
{
|
|
dm_exception_store_type_unregister(&_persistent_type);
|
|
dm_exception_store_type_unregister(&_persistent_compat_type);
|
|
}
|