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![Christoph Hellwig](/assets/img/avatar_default.png)
Remove the WRITE_* and READ_SYNC wrappers, and just use the flags directly. Where applicable this also drops usage of the bio_set_op_attrs wrapper. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
977 lines
23 KiB
C
977 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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/*
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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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|
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/* presume the area is full */
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*full = 1;
|
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|
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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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* 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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* Keep track of the start of the free chunks.
|
|
*/
|
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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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* Otherwise we add the exception to the snapshot.
|
|
*/
|
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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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}
|
|
|
|
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),
|
|
void *callback_context)
|
|
{
|
|
int r, full = 1;
|
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struct dm_bufio_client *client;
|
|
chunk_t prefetch_area = 0;
|
|
|
|
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);
|
|
|
|
if (IS_ERR(client))
|
|
return PTR_ERR(client);
|
|
|
|
/*
|
|
* Setup for one current buffer + desired readahead buffers.
|
|
*/
|
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dm_bufio_set_minimum_buffers(client, 1 + DM_PREFETCH_CHUNKS);
|
|
|
|
/*
|
|
* Keeping reading chunks and inserting exceptions until
|
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* 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))
|
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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;
|
|
} while (prefetch_area <= ps->current_area + DM_PREFETCH_CHUNKS);
|
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|
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chunk = area_location(ps, ps->current_area);
|
|
|
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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;
|
|
}
|
|
|
|
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))
|
|
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);
|
|
}
|