3859ad36f0
The reference owned by the user/monitor that is created when adding the export and dropped when removing it was tied to the 'exports' list in nbd/server.c. Every block export will have a user reference, so move it to the block export level and tie it to the 'block_exports' list in block/export/export.c instead. This is necessary for introducing a QMP command for removing exports. Note that exports are present in block_exports even after the user has requested shutdown. This is different from NBD's exports where exports are immediately removed on a shutdown request, even if they are still in the process of shutting down. In order to avoid that the user still interacts with an export that is shutting down (and possibly removes it a second time), we need to remember if the user actually still owns it. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-Id: <20200924152717.287415-20-kwolf@redhat.com> Acked-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
86 lines
2.3 KiB
C
86 lines
2.3 KiB
C
/*
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* Declarations for block exports
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*
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* Copyright (c) 2012, 2020 Red Hat, Inc.
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*
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* Authors:
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* Paolo Bonzini <pbonzini@redhat.com>
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* Kevin Wolf <kwolf@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or
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* later. See the COPYING file in the top-level directory.
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*/
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#ifndef BLOCK_EXPORT_H
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#define BLOCK_EXPORT_H
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#include "qapi/qapi-types-block-export.h"
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#include "qemu/queue.h"
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typedef struct BlockExport BlockExport;
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typedef struct BlockExportDriver {
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/* The export type that this driver services */
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BlockExportType type;
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/*
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* The size of the driver-specific state that contains BlockExport as its
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* first field.
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*/
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size_t instance_size;
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/* Creates and starts a new block export */
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int (*create)(BlockExport *, BlockExportOptions *, Error **);
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/*
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* Frees a removed block export. This function is only called after all
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* references have been dropped.
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*/
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void (*delete)(BlockExport *);
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/*
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* Start to disconnect all clients and drop other references held
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* internally by the export driver. When the function returns, there may
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* still be active references while the export is in the process of
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* shutting down.
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*/
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void (*request_shutdown)(BlockExport *);
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} BlockExportDriver;
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struct BlockExport {
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const BlockExportDriver *drv;
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/* Unique identifier for the export */
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char *id;
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/*
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* Reference count for this block export. This includes strong references
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* both from the owner (qemu-nbd or the monitor) and clients connected to
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* the export.
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*/
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int refcount;
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/*
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* True if one of the references in refcount belongs to the user. After the
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* user has dropped their reference, they may not e.g. remove the same
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* export a second time (which would decrease the refcount without having
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* it incremented first).
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*/
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bool user_owned;
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/* The AioContext whose lock protects this BlockExport object. */
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AioContext *ctx;
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/* List entry for block_exports */
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QLIST_ENTRY(BlockExport) next;
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};
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BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp);
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void blk_exp_ref(BlockExport *exp);
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void blk_exp_unref(BlockExport *exp);
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void blk_exp_request_shutdown(BlockExport *exp);
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void blk_exp_close_all(void);
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void blk_exp_close_all_type(BlockExportType type);
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#endif
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