7328508274
Remove artificial maximum 256 loop device that can be created due to a legacy device number limit. Searching through lkml archive, there are several instances where users complained about the artificial limit that the loop driver impose. There is no reason to have such limit. This patch rid the limit entirely and make loop device and associated block queue instantiation on demand. With on-demand instantiation, it also gives the benefit of not wasting memory if these devices are not in use (compare to current implementation that always create 8 loop devices), a net improvement in both areas. This version is both tested with creation of large number of loop devices and is compatible with existing losetup/mount user land tools. There are a number of people who worked on this and provided valuable suggestions, in no particular order, by: Jens Axboe Jan Engelhardt Christoph Hellwig Thomas M Signed-off-by: Ken Chen <kenchen@google.com> Cc: Jan Engelhardt <jengelh@linux01.gwdg.de> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
164 lines
4 KiB
C
164 lines
4 KiB
C
#ifndef _LINUX_LOOP_H
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#define _LINUX_LOOP_H
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/*
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* include/linux/loop.h
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*
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* Written by Theodore Ts'o, 3/29/93.
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*
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* Copyright 1993 by Theodore Ts'o. Redistribution of this file is
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* permitted under the GNU General Public License.
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*/
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#define LO_NAME_SIZE 64
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#define LO_KEY_SIZE 32
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#ifdef __KERNEL__
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#include <linux/bio.h>
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#include <linux/blkdev.h>
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#include <linux/spinlock.h>
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#include <linux/mutex.h>
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/* Possible states of device */
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enum {
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Lo_unbound,
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Lo_bound,
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Lo_rundown,
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};
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struct loop_func_table;
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struct loop_device {
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int lo_number;
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int lo_refcnt;
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loff_t lo_offset;
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loff_t lo_sizelimit;
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int lo_flags;
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int (*transfer)(struct loop_device *, int cmd,
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struct page *raw_page, unsigned raw_off,
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struct page *loop_page, unsigned loop_off,
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int size, sector_t real_block);
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char lo_file_name[LO_NAME_SIZE];
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char lo_crypt_name[LO_NAME_SIZE];
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char lo_encrypt_key[LO_KEY_SIZE];
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int lo_encrypt_key_size;
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struct loop_func_table *lo_encryption;
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__u32 lo_init[2];
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uid_t lo_key_owner; /* Who set the key */
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int (*ioctl)(struct loop_device *, int cmd,
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unsigned long arg);
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struct file * lo_backing_file;
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struct block_device *lo_device;
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unsigned lo_blocksize;
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void *key_data;
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gfp_t old_gfp_mask;
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spinlock_t lo_lock;
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struct bio *lo_bio;
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struct bio *lo_biotail;
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int lo_state;
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struct mutex lo_ctl_mutex;
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struct task_struct *lo_thread;
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wait_queue_head_t lo_event;
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request_queue_t *lo_queue;
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struct gendisk *lo_disk;
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struct list_head lo_list;
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};
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#endif /* __KERNEL__ */
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/*
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* Loop flags
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*/
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enum {
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LO_FLAGS_READ_ONLY = 1,
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LO_FLAGS_USE_AOPS = 2,
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};
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#include <asm/posix_types.h> /* for __kernel_old_dev_t */
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#include <asm/types.h> /* for __u64 */
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/* Backwards compatibility version */
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struct loop_info {
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int lo_number; /* ioctl r/o */
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__kernel_old_dev_t lo_device; /* ioctl r/o */
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unsigned long lo_inode; /* ioctl r/o */
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__kernel_old_dev_t lo_rdevice; /* ioctl r/o */
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int lo_offset;
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int lo_encrypt_type;
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int lo_encrypt_key_size; /* ioctl w/o */
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int lo_flags; /* ioctl r/o */
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char lo_name[LO_NAME_SIZE];
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unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
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unsigned long lo_init[2];
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char reserved[4];
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};
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struct loop_info64 {
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__u64 lo_device; /* ioctl r/o */
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__u64 lo_inode; /* ioctl r/o */
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__u64 lo_rdevice; /* ioctl r/o */
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__u64 lo_offset;
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__u64 lo_sizelimit;/* bytes, 0 == max available */
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__u32 lo_number; /* ioctl r/o */
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__u32 lo_encrypt_type;
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__u32 lo_encrypt_key_size; /* ioctl w/o */
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__u32 lo_flags; /* ioctl r/o */
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__u8 lo_file_name[LO_NAME_SIZE];
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__u8 lo_crypt_name[LO_NAME_SIZE];
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__u8 lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
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__u64 lo_init[2];
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};
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/*
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* Loop filter types
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*/
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#define LO_CRYPT_NONE 0
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#define LO_CRYPT_XOR 1
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#define LO_CRYPT_DES 2
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#define LO_CRYPT_FISH2 3 /* Twofish encryption */
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#define LO_CRYPT_BLOW 4
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#define LO_CRYPT_CAST128 5
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#define LO_CRYPT_IDEA 6
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#define LO_CRYPT_DUMMY 9
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#define LO_CRYPT_SKIPJACK 10
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#define LO_CRYPT_CRYPTOAPI 18
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#define MAX_LO_CRYPT 20
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#ifdef __KERNEL__
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/* Support for loadable transfer modules */
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struct loop_func_table {
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int number; /* filter type */
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int (*transfer)(struct loop_device *lo, int cmd,
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struct page *raw_page, unsigned raw_off,
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struct page *loop_page, unsigned loop_off,
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int size, sector_t real_block);
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int (*init)(struct loop_device *, const struct loop_info64 *);
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/* release is called from loop_unregister_transfer or clr_fd */
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int (*release)(struct loop_device *);
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int (*ioctl)(struct loop_device *, int cmd, unsigned long arg);
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struct module *owner;
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};
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int loop_register_transfer(struct loop_func_table *funcs);
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int loop_unregister_transfer(int number);
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#endif
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/*
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* IOCTL commands --- we will commandeer 0x4C ('L')
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*/
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#define LOOP_SET_FD 0x4C00
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#define LOOP_CLR_FD 0x4C01
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#define LOOP_SET_STATUS 0x4C02
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#define LOOP_GET_STATUS 0x4C03
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#define LOOP_SET_STATUS64 0x4C04
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#define LOOP_GET_STATUS64 0x4C05
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#define LOOP_CHANGE_FD 0x4C06
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#endif
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