ef295ecf09
Now that we don't need the common flags to overflow outside the range of a 32-bit type we can encode them the same way for both the bio and request fields. This in addition allows us to place the operation first (and make some room for more ops while we're at it) and to stop having to shift around the operation values. In addition this allows passing around only one value in the block layer instead of two (and eventuall also in the file systems, but we can do that later) and thus clean up a lot of code. Last but not least this allows decreasing the size of the cmd_flags field in struct request to 32-bits. Various functions passing this value could also be updated, but I'd like to avoid the churn for now. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
85 lines
1.9 KiB
C
85 lines
1.9 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_BIO, /* 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 *bio;
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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_op; /* REQ_OP */
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int bi_op_flags; /* req_flag_bits */
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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(void);
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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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