mirror of
https://github.com/torvalds/linux
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b0d3cc011e
Commit76c44f6d80introduced the possibly for "Overflow" to be reported by the snapshot device's status. Older userspace (e.g. lvm2) does not handle the "Overflow" status response. Fix this incompatibility by requiring newer userspace code, that can cope with "Overflow", request the persistent store with overflow support by using "PO" (Persistent with Overflow) for the snapshot store type. Reported-by: Zdenek Kabelac <zkabelac@redhat.com> Fixes:76c44f6d80("dm snapshot: don't invalidate on-disk image on snapshot write overflow") Reviewed-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
152 lines
3.6 KiB
C
152 lines
3.6 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/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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#define DM_MSG_PREFIX "transient snapshot"
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/*-----------------------------------------------------------------
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* Implementation of the store for non-persistent snapshots.
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*---------------------------------------------------------------*/
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struct transient_c {
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sector_t next_free;
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};
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static void transient_dtr(struct dm_exception_store *store)
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{
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kfree(store->context);
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}
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static int transient_read_metadata(struct dm_exception_store *store,
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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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{
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return 0;
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}
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static int transient_prepare_exception(struct dm_exception_store *store,
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struct dm_exception *e)
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{
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struct transient_c *tc = store->context;
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sector_t size = get_dev_size(dm_snap_cow(store->snap)->bdev);
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if (size < (tc->next_free + store->chunk_size))
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return -1;
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e->new_chunk = sector_to_chunk(store, tc->next_free);
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tc->next_free += store->chunk_size;
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return 0;
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}
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static void transient_commit_exception(struct dm_exception_store *store,
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struct dm_exception *e,
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void (*callback) (void *, int success),
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void *callback_context)
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{
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/* Just succeed */
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callback(callback_context, 1);
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}
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static void transient_usage(struct dm_exception_store *store,
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sector_t *total_sectors,
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sector_t *sectors_allocated,
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sector_t *metadata_sectors)
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{
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*sectors_allocated = ((struct transient_c *) store->context)->next_free;
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*total_sectors = get_dev_size(dm_snap_cow(store->snap)->bdev);
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*metadata_sectors = 0;
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}
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static int transient_ctr(struct dm_exception_store *store, char *options)
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{
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struct transient_c *tc;
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tc = kmalloc(sizeof(struct transient_c), GFP_KERNEL);
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if (!tc)
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return -ENOMEM;
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tc->next_free = 0;
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store->context = tc;
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return 0;
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}
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static unsigned transient_status(struct dm_exception_store *store,
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status_type_t status, char *result,
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unsigned maxlen)
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{
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unsigned sz = 0;
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switch (status) {
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case STATUSTYPE_INFO:
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break;
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case STATUSTYPE_TABLE:
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DMEMIT(" N %llu", (unsigned long long)store->chunk_size);
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}
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return sz;
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}
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static struct dm_exception_store_type _transient_type = {
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.name = "transient",
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.module = THIS_MODULE,
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.ctr = transient_ctr,
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.dtr = transient_dtr,
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.read_metadata = transient_read_metadata,
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.prepare_exception = transient_prepare_exception,
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.commit_exception = transient_commit_exception,
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.usage = transient_usage,
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.status = transient_status,
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};
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static struct dm_exception_store_type _transient_compat_type = {
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.name = "N",
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.module = THIS_MODULE,
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.ctr = transient_ctr,
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.dtr = transient_dtr,
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.read_metadata = transient_read_metadata,
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.prepare_exception = transient_prepare_exception,
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.commit_exception = transient_commit_exception,
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.usage = transient_usage,
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.status = transient_status,
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};
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int dm_transient_snapshot_init(void)
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{
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int r;
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r = dm_exception_store_type_register(&_transient_type);
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if (r) {
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DMWARN("Unable to register transient exception store type");
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return r;
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}
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r = dm_exception_store_type_register(&_transient_compat_type);
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if (r) {
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DMWARN("Unable to register old-style transient "
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"exception store type");
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dm_exception_store_type_unregister(&_transient_type);
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return r;
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}
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return r;
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}
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void dm_transient_snapshot_exit(void)
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{
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dm_exception_store_type_unregister(&_transient_type);
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dm_exception_store_type_unregister(&_transient_compat_type);
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}
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