924e600d41
Eliminate a 4-byte hole in 'struct dm_io_memory' by moving 'offset' above the 'ptr' to which it applies (size reduced from 24 to 16 bytes). And by association, 1-4 byte hole is eliminated in 'struct dm_io_request' (size reduced from 56 to 48 bytes). Eliminate all 6 4-byte holes and 1 cache-line in 'struct dm_snapshot' (size reduced from 392 to 368 bytes). Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
86 lines
2.0 KiB
C
86 lines
2.0 KiB
C
/*
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* Copyright (C) 2003 Sistina Software
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* Copyright (C) 2004 - 2008 Red Hat, Inc. All rights reserved.
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*
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* Device-Mapper low-level I/O.
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*
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* This file is released under the GPL.
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*/
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#ifndef _LINUX_DM_IO_H
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#define _LINUX_DM_IO_H
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#ifdef __KERNEL__
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#include <linux/types.h>
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struct dm_io_region {
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struct block_device *bdev;
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sector_t sector;
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sector_t count; /* If this is zero the region is ignored. */
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};
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struct page_list {
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struct page_list *next;
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struct page *page;
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};
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typedef void (*io_notify_fn)(unsigned long error, void *context);
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enum dm_io_mem_type {
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DM_IO_PAGE_LIST,/* Page list */
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DM_IO_BVEC, /* Bio vector */
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DM_IO_VMA, /* Virtual memory area */
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DM_IO_KMEM, /* Kernel memory */
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};
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struct dm_io_memory {
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enum dm_io_mem_type type;
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unsigned offset;
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union {
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struct page_list *pl;
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struct bio_vec *bvec;
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void *vma;
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void *addr;
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} ptr;
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};
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struct dm_io_notify {
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io_notify_fn fn; /* Callback for asynchronous requests */
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void *context; /* Passed to callback */
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};
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/*
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* IO request structure
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*/
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struct dm_io_client;
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struct dm_io_request {
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int bi_rw; /* READ|WRITE - not READA */
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struct dm_io_memory mem; /* Memory to use for io */
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struct dm_io_notify notify; /* Synchronous if notify.fn is NULL */
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struct dm_io_client *client; /* Client memory handler */
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};
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/*
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* For async io calls, users can alternatively use the dm_io() function below
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* and dm_io_client_create() to create private mempools for the client.
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*
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* Create/destroy may block.
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*/
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struct dm_io_client *dm_io_client_create(unsigned num_pages);
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int dm_io_client_resize(unsigned num_pages, struct dm_io_client *client);
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void dm_io_client_destroy(struct dm_io_client *client);
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/*
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* IO interface using private per-client pools.
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* Each bit in the optional 'sync_error_bits' bitset indicates whether an
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* error occurred doing io to the corresponding region.
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*/
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int dm_io(struct dm_io_request *io_req, unsigned num_regions,
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struct dm_io_region *region, unsigned long *sync_error_bits);
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#endif /* __KERNEL__ */
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#endif /* _LINUX_DM_IO_H */
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