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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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7b5a35225b
Currently there is not limitation of number of requests in the loop bio list. This can lead into some nasty situations when the caller spawns tons of bio requests taking huge amount of memory. This is even more obvious with discard where blkdev_issue_discard() will submit all bios for the range and wait for them to finish afterwards. On really big loop devices and slow backing file system this can lead to OOM situation as reported by Dave Chinner. With this patch we will wait in loop_make_request() if the number of bios in the loop bio list would exceed 'nr_congestion_on'. We'll wake up the process as we process the bios form the list. Some threshold hysteresis is in place to avoid high frequency oscillation. Signed-off-by: Lukas Czerner <lczerner@redhat.com> Reported-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
86 lines
2.2 KiB
C
86 lines
2.2 KiB
C
/*
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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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#ifndef _LINUX_LOOP_H
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#define _LINUX_LOOP_H
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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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#include <uapi/linux/loop.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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kuid_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_list lo_bio_list;
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unsigned int lo_bio_count;
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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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/* wait queue for incoming requests */
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wait_queue_head_t lo_req_wait;
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struct request_queue *lo_queue;
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struct gendisk *lo_disk;
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};
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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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