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lvm2/lib/device/device.h
Alasdair G Kergon bd0967a4b1 device: Keep the last data buffer read off each device.
If there's a second metadata area on device, we record that separately.

Note that the memory requirements aren't restricted yet.
2018-01-10 15:48:03 +00:00

200 lines
6.6 KiB
C

/*
* Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
* Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved.
*
* This file is part of LVM2.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU Lesser General Public License v.2.1.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef _LVM_DEVICE_H
#define _LVM_DEVICE_H
#include "uuid.h"
#include <fcntl.h>
#define DEV_ACCESSED_W 0x00000001 /* Device written to? */
#define DEV_REGULAR 0x00000002 /* Regular file? */
#define DEV_ALLOCED 0x00000004 /* dm_malloc used */
#define DEV_OPENED_RW 0x00000008 /* Opened RW */
#define DEV_OPENED_EXCL 0x00000010 /* Opened EXCL */
#define DEV_O_DIRECT 0x00000020 /* Use O_DIRECT */
#define DEV_O_DIRECT_TESTED 0x00000040 /* DEV_O_DIRECT is reliable */
#define DEV_OPEN_FAILURE 0x00000080 /* Has last open failed? */
#define DEV_USED_FOR_LV 0x00000100 /* Is device used for an LV */
#define DEV_ASSUMED_FOR_LV 0x00000200 /* Is device assumed for an LV */
#define DEV_NOT_O_NOATIME 0x00000400 /* Don't use O_NOATIME */
/*
* Standard format for callback functions.
* When provided, callback functions are called exactly once.
* If failed is set, data cannot be accessed.
*/
typedef void (*lvm_callback_fn_t)(int failed, void *context, void *data);
/*
* Support for external device info.
* Any new external device info source needs to be
* registered using EXT_REGISTER macro in dev-ext.c.
*/
typedef enum dev_ext_e {
DEV_EXT_NONE,
DEV_EXT_UDEV,
DEV_EXT_NUM
} dev_ext_t;
struct dev_ext {
int enabled;
dev_ext_t src;
void *handle;
};
struct device_area {
struct device *dev;
uint64_t start; /* Bytes */
uint64_t size; /* Bytes */
};
struct device_buffer {
void *data; /* Location of start of requested data (inside buf) */
/* Private */
void *malloc_address; /* Start of allocated memory */
void *buf; /* Aligned buffer that contains data within it */
struct device_area where; /* Location of buf */
unsigned write:1; /* 1 if write; 0 if read */
};
/*
* All devices in LVM will be represented by one of these.
* pointer comparisons are valid.
*/
struct device {
struct dm_list aliases; /* struct dm_str_list */
dev_t dev;
/* private */
int fd;
int open_count;
int error_count;
int max_error_count;
int phys_block_size;
int block_size;
int read_ahead;
uint32_t flags;
unsigned size_seqno;
uint64_t size;
uint64_t end;
struct dm_list open_list;
struct dev_ext ext;
struct device_buffer last_devbuf; /* Last data buffer read from the device */
struct device_buffer last_extra_devbuf; /* Last data buffer read from the device for extra metadata area */
const char *vgid; /* if device is an LV */
const char *lvid; /* if device is an LV */
char pvid[ID_LEN + 1]; /* if device is a PV */
char _padding[7];
};
/*
* All I/O is annotated with the reason it is performed.
*/
typedef enum dev_io_reason {
DEV_IO_SIGNATURES = 0, /* Scanning device signatures */
DEV_IO_LABEL, /* LVM PV disk label */
DEV_IO_MDA_HEADER, /* Text format metadata area header */
DEV_IO_MDA_CONTENT, /* Text format metadata area content */
DEV_IO_MDA_EXTRA_HEADER, /* Header of any extra metadata areas on device */
DEV_IO_MDA_EXTRA_CONTENT, /* Content of any extra metadata areas on device */
DEV_IO_FMT1, /* Original LVM1 metadata format */
DEV_IO_POOL, /* Pool metadata format */
DEV_IO_LV, /* Content written to an LV */
DEV_IO_LOG /* Logging messages */
} dev_io_reason_t;
/*
* Is this I/O for a device's extra metadata area?
*/
#define EXTRA_IO(reason) ((reason) == DEV_IO_MDA_EXTRA_HEADER || (reason) == DEV_IO_MDA_EXTRA_CONTENT)
struct device_list {
struct dm_list list;
struct device *dev;
};
/*
* Support for external device info.
*/
const char *dev_ext_name(struct device *dev);
int dev_ext_enable(struct device *dev, dev_ext_t src);
int dev_ext_disable(struct device *dev);
struct dev_ext *dev_ext_get(struct device *dev);
int dev_ext_release(struct device *dev);
/*
* Increment current dev_size_seqno.
* This is used to control lifetime
* of cached device size.
*/
void dev_size_seqno_inc(void);
/*
* All io should use these routines.
*/
int dev_get_block_size(struct device *dev, unsigned int *phys_block_size, unsigned int *block_size);
int dev_get_size(struct device *dev, uint64_t *size);
int dev_get_read_ahead(struct device *dev, uint32_t *read_ahead);
int dev_discard_blocks(struct device *dev, uint64_t offset_bytes, uint64_t size_bytes);
/* Use quiet version if device number could change e.g. when opening LV */
int dev_open(struct device *dev);
int dev_open_quiet(struct device *dev);
int dev_open_flags(struct device *dev, int flags, int direct, int quiet);
int dev_open_readonly(struct device *dev);
int dev_open_readonly_buffered(struct device *dev);
int dev_open_readonly_quiet(struct device *dev);
int dev_close(struct device *dev);
int dev_close_immediate(struct device *dev);
void dev_close_all(void);
int dev_test_excl(struct device *dev);
int dev_fd(struct device *dev);
const char *dev_name(const struct device *dev);
/* Returns a read-only buffer */
char *dev_read(struct device *dev, uint64_t offset, size_t len, dev_io_reason_t reason);
char *dev_read_circular(struct device *dev, uint64_t offset, size_t len,
uint64_t offset2, size_t len2, dev_io_reason_t reason);
/* Passes the data to dev_read_callback_fn */
int dev_read_callback(struct device *dev, uint64_t offset, size_t len, dev_io_reason_t reason,
lvm_callback_fn_t dev_read_callback_fn, void *callback_context);
/* Read data and copy it into a supplied private buffer. */
/* Only use for tiny reads or on unimportant code paths. */
int dev_read_buf(struct device *dev, uint64_t offset, size_t len, dev_io_reason_t reason, void *retbuf);
int dev_write(struct device *dev, uint64_t offset, size_t len, dev_io_reason_t reason, void *buffer);
int dev_append(struct device *dev, size_t len, dev_io_reason_t reason, char *buffer);
int dev_set(struct device *dev, uint64_t offset, size_t len, dev_io_reason_t reason, int value);
void dev_flush(struct device *dev);
struct device *dev_create_file(const char *filename, struct device *dev,
struct dm_str_list *alias, int use_malloc);
void dev_destroy_file(struct device *dev);
void devbufs_release(struct device *dev);
/* Return a valid device name from the alias list; NULL otherwise */
const char *dev_name_confirmed(struct device *dev, int quiet);
#endif