4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 only,
8 * as published by the Free Software Foundation.
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License version 2 for more details (a copy is included
14 * in the LICENSE file that accompanied this code).
16 * You should have received a copy of the GNU General Public License
17 * version 2 along with this program; If not, see
18 * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
20 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
21 * CA 95054 USA or visit www.sun.com if you need additional information or
27 * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
28 * Use is subject to license terms.
30 * Copyright (c) 2011, 2012, Intel Corporation.
33 * This file is part of Lustre, http://www.lustre.org/
34 * Lustre is a trademark of Sun Microsystems, Inc.
38 * linux/drivers/block/loop.c
40 * Written by Theodore Ts'o, 3/29/93
42 * Copyright 1993 by Theodore Ts'o. Redistribution of this file is
43 * permitted under the GNU General Public License.
45 * Modularized and updated for 1.1.16 kernel - Mitch Dsouza 28th May 1994
46 * Adapted for 1.3.59 kernel - Andries Brouwer, 1 Feb 1996
48 * Fixed do_loop_request() re-entrancy - Vincent.Renardias@waw.com Mar 20, 1997
50 * Added devfs support - Richard Gooch <rgooch@atnf.csiro.au> 16-Jan-1998
52 * Handle sparse backing files correctly - Kenn Humborg, Jun 28, 1998
54 * Loadable modules and other fixes by AK, 1998
56 * Maximum number of loop devices now dynamic via max_loop module parameter.
57 * Russell Kroll <rkroll@exploits.org> 19990701
59 * Maximum number of loop devices when compiled-in now selectable by passing
60 * max_loop=<1-255> to the kernel on boot.
61 * Erik I. Bols?, <eriki@himolde.no>, Oct 31, 1999
63 * Completely rewrite request handling to be make_request_fn style and
64 * non blocking, pushing work to a helper thread. Lots of fixes from
66 * Jens Axboe <axboe@suse.de>, Nov 2000
68 * Support up to 256 loop devices
69 * Heinz Mauelshagen <mge@sistina.com>, Feb 2002
71 * Support for falling back on the write file operation when the address space
72 * operations prepare_write and/or commit_write are not available on the
74 * Anton Altaparmakov, 16 Feb 2005
77 * - Advisory locking is ignored here.
78 * - Should use an own CAP_* category instead of CAP_SYS_ADMIN
82 #include <linux/module.h>
84 #include <linux/sched.h>
86 #include <linux/file.h>
87 #include <linux/stat.h>
88 #include <linux/errno.h>
89 #include <linux/major.h>
90 #include <linux/wait.h>
91 #include <linux/blkdev.h>
92 #include <linux/blkpg.h>
93 #include <linux/init.h>
94 #include <linux/swap.h>
95 #include <linux/slab.h>
96 #include <linux/suspend.h>
97 #include <linux/writeback.h>
98 #include <linux/buffer_head.h> /* for invalidate_bdev() */
99 #include <linux/completion.h>
100 #include <linux/highmem.h>
101 #include <linux/gfp.h>
102 #include <linux/pagevec.h>
103 #include <linux/uaccess.h>
105 #include "../include/lustre_lib.h"
106 #include "../include/lustre_lite.h"
107 #include "llite_internal.h"
109 #define LLOOP_MAX_SEGMENTS LNET_MAX_IOV
111 /* Possible states of device */
118 struct lloop_device {
124 struct file *lo_backing_file;
125 struct block_device *lo_device;
126 unsigned lo_blocksize;
132 struct bio *lo_biotail;
134 struct semaphore lo_sem;
135 struct mutex lo_ctl_mutex;
137 wait_queue_head_t lo_bh_wait;
139 struct request_queue *lo_queue;
141 const struct lu_env *lo_env;
143 struct ll_dio_pages lo_pvec;
145 /* data to handle bio for lustre. */
146 struct lo_request_data {
147 struct page *lrd_pages[LLOOP_MAX_SEGMENTS];
148 loff_t lrd_offsets[LLOOP_MAX_SEGMENTS];
156 LO_FLAGS_READ_ONLY = 1,
159 static int lloop_major;
160 #define MAX_LOOP_DEFAULT 16
161 static int max_loop = MAX_LOOP_DEFAULT;
162 static struct lloop_device *loop_dev;
163 static struct gendisk **disks;
164 static struct mutex lloop_mutex;
165 static void *ll_iocontrol_magic;
167 static loff_t get_loop_size(struct lloop_device *lo, struct file *file)
169 loff_t size, offset, loopsize;
171 /* Compute loopsize in bytes */
172 size = i_size_read(file->f_mapping->host);
173 offset = lo->lo_offset;
174 loopsize = size - offset;
175 if (lo->lo_sizelimit > 0 && lo->lo_sizelimit < loopsize)
176 loopsize = lo->lo_sizelimit;
179 * Unfortunately, if we want to do I/O on the device,
180 * the number of 512-byte sectors has to fit into a sector_t.
182 return loopsize >> 9;
185 static int do_bio_lustrebacked(struct lloop_device *lo, struct bio *head)
187 const struct lu_env *env = lo->lo_env;
188 struct cl_io *io = &lo->lo_io;
189 struct inode *inode = file_inode(lo->lo_backing_file);
190 struct cl_object *obj = ll_i2info(inode)->lli_clob;
196 struct bvec_iter iter;
200 struct ll_dio_pages *pvec = &lo->lo_pvec;
201 struct page **pages = pvec->ldp_pages;
202 loff_t *offsets = pvec->ldp_offsets;
204 truncate_inode_pages(inode->i_mapping, 0);
206 /* initialize the IO */
207 memset(io, 0, sizeof(*io));
209 ret = cl_io_init(env, io, CIT_MISC, obj);
211 return io->ci_result;
212 io->ci_lockreq = CILR_NEVER;
214 rw = bio_data_dir(head);
215 for (bio = head; bio ; bio = bio->bi_next) {
216 LASSERT(rw == bio_data_dir(bio));
218 offset = (pgoff_t)(bio->bi_iter.bi_sector << 9) + lo->lo_offset;
219 bio_for_each_segment(bvec, bio, iter) {
220 BUG_ON(bvec.bv_offset != 0);
221 BUG_ON(bvec.bv_len != PAGE_SIZE);
223 pages[page_count] = bvec.bv_page;
224 offsets[page_count] = offset;
226 offset += bvec.bv_len;
228 LASSERT(page_count <= LLOOP_MAX_SEGMENTS);
231 ll_stats_ops_tally(ll_i2sbi(inode),
232 (rw == WRITE) ? LPROC_LL_BRW_WRITE : LPROC_LL_BRW_READ,
235 pvec->ldp_size = page_count << PAGE_SHIFT;
236 pvec->ldp_nr = page_count;
238 /* FIXME: in ll_direct_rw_pages, it has to allocate many cl_page{}s to
239 * write those pages into OST. Even worse case is that more pages
240 * would be asked to write out to swap space, and then finally get here
242 * Unfortunately this is NOT easy to fix.
243 * Thoughts on solution:
244 * 0. Define a reserved pool for cl_pages, which could be a list of
245 * pre-allocated cl_pages;
246 * 1. Define a new operation in cl_object_operations{}, says clo_depth,
247 * which measures how many layers for this lustre object. Generally
248 * speaking, the depth would be 2, one for llite, and one for lovsub.
249 * However, for SNS, there will be more since we need additional page
251 * 2. Reserve the # of (page_count * depth) cl_pages from the reserved
252 * pool. Afterwards, the clio would allocate the pages from reserved
253 * pool, this guarantees we needn't allocate the cl_pages from
254 * generic cl_page slab cache.
255 * Of course, if there is NOT enough pages in the pool, we might
256 * be asked to write less pages once, this purely depends on
257 * implementation. Anyway, we should be careful to avoid deadlocking.
260 bytes = ll_direct_rw_pages(env, io, rw, inode, pvec);
263 return (bytes == pvec->ldp_size) ? 0 : (int)bytes;
267 * Add bio to back of pending list
269 static void loop_add_bio(struct lloop_device *lo, struct bio *bio)
273 spin_lock_irqsave(&lo->lo_lock, flags);
274 if (lo->lo_biotail) {
275 lo->lo_biotail->bi_next = bio;
276 lo->lo_biotail = bio;
278 lo->lo_bio = lo->lo_biotail = bio;
280 spin_unlock_irqrestore(&lo->lo_lock, flags);
282 atomic_inc(&lo->lo_pending);
283 if (waitqueue_active(&lo->lo_bh_wait))
284 wake_up(&lo->lo_bh_wait);
288 * Grab first pending buffer
290 static unsigned int loop_get_bio(struct lloop_device *lo, struct bio **req)
294 unsigned int count = 0;
295 unsigned int page_count = 0;
298 spin_lock_irq(&lo->lo_lock);
300 if (unlikely(!first)) {
301 spin_unlock_irq(&lo->lo_lock);
305 /* TODO: need to split the bio, too bad. */
306 LASSERT(first->bi_vcnt <= LLOOP_MAX_SEGMENTS);
308 rw = bio_data_dir(first);
310 while (*bio && (*bio)->bi_rw == rw) {
311 CDEBUG(D_INFO, "bio sector %llu size %u count %u vcnt%u\n",
312 (unsigned long long)(*bio)->bi_iter.bi_sector,
313 (*bio)->bi_iter.bi_size,
314 page_count, (*bio)->bi_vcnt);
315 if (page_count + (*bio)->bi_vcnt > LLOOP_MAX_SEGMENTS)
318 page_count += (*bio)->bi_vcnt;
320 bio = &(*bio)->bi_next;
323 /* Some of bios can't be mergeable. */
327 /* Hit the end of queue */
328 lo->lo_biotail = NULL;
332 spin_unlock_irq(&lo->lo_lock);
336 static blk_qc_t loop_make_request(struct request_queue *q, struct bio *old_bio)
338 struct lloop_device *lo = q->queuedata;
339 int rw = bio_rw(old_bio);
342 blk_queue_split(q, &old_bio, q->bio_split);
347 CDEBUG(D_INFO, "submit bio sector %llu size %u\n",
348 (unsigned long long)old_bio->bi_iter.bi_sector,
349 old_bio->bi_iter.bi_size);
351 spin_lock_irq(&lo->lo_lock);
352 inactive = lo->lo_state != LLOOP_BOUND;
353 spin_unlock_irq(&lo->lo_lock);
358 if (lo->lo_flags & LO_FLAGS_READ_ONLY)
360 } else if (rw == READA) {
362 } else if (rw != READ) {
363 CERROR("lloop: unknown command (%x)\n", rw);
366 loop_add_bio(lo, old_bio);
367 return BLK_QC_T_NONE;
369 bio_io_error(old_bio);
370 return BLK_QC_T_NONE;
373 static inline void loop_handle_bio(struct lloop_device *lo, struct bio *bio)
377 ret = do_bio_lustrebacked(lo, bio);
379 struct bio *tmp = bio->bi_next;
388 static inline int loop_active(struct lloop_device *lo)
390 return atomic_read(&lo->lo_pending) ||
391 (lo->lo_state == LLOOP_RUNDOWN);
395 * worker thread that handles reads/writes to file backed loop devices,
396 * to avoid blocking in our make_request_fn.
398 static int loop_thread(void *data)
400 struct lloop_device *lo = data;
403 unsigned long times = 0;
404 unsigned long total_count = 0;
410 set_user_nice(current, MIN_NICE);
412 lo->lo_state = LLOOP_BOUND;
414 env = cl_env_get(&refcheck);
421 memset(&lo->lo_pvec, 0, sizeof(lo->lo_pvec));
422 lo->lo_pvec.ldp_pages = lo->lo_requests[0].lrd_pages;
423 lo->lo_pvec.ldp_offsets = lo->lo_requests[0].lrd_offsets;
426 * up sem, we are running
431 wait_event(lo->lo_bh_wait, loop_active(lo));
432 if (!atomic_read(&lo->lo_pending)) {
435 spin_lock_irq(&lo->lo_lock);
436 exiting = (lo->lo_state == LLOOP_RUNDOWN);
437 spin_unlock_irq(&lo->lo_lock);
443 count = loop_get_bio(lo, &bio);
445 CWARN("lloop(minor: %d): missing bio\n", lo->lo_number);
449 total_count += count;
450 if (total_count < count) { /* overflow */
456 if ((times & 127) == 0) {
457 CDEBUG(D_INFO, "total: %lu, count: %lu, avg: %lu\n",
458 total_count, times, total_count / times);
462 LASSERT(count <= atomic_read(&lo->lo_pending));
463 loop_handle_bio(lo, bio);
464 atomic_sub(count, &lo->lo_pending);
466 cl_env_put(env, &refcheck);
473 static int loop_set_fd(struct lloop_device *lo, struct file *unused,
474 struct block_device *bdev, struct file *file)
477 struct address_space *mapping;
482 if (!try_module_get(THIS_MODULE))
486 if (lo->lo_state != LLOOP_UNBOUND)
489 mapping = file->f_mapping;
490 inode = mapping->host;
493 if (!S_ISREG(inode->i_mode) || inode->i_sb->s_magic != LL_SUPER_MAGIC)
496 if (!(file->f_mode & FMODE_WRITE))
497 lo_flags |= LO_FLAGS_READ_ONLY;
499 size = get_loop_size(lo, file);
501 if ((loff_t)(sector_t)size != size) {
506 /* remove all pages in cache so as dirty pages not to be existent. */
507 truncate_inode_pages(mapping, 0);
509 set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
511 lo->lo_blocksize = PAGE_SIZE;
512 lo->lo_device = bdev;
513 lo->lo_flags = lo_flags;
514 lo->lo_backing_file = file;
515 lo->lo_sizelimit = 0;
516 lo->old_gfp_mask = mapping_gfp_mask(mapping);
517 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
519 lo->lo_bio = lo->lo_biotail = NULL;
522 * set queue make_request_fn, and add limits based on lower level
525 blk_queue_make_request(lo->lo_queue, loop_make_request);
526 lo->lo_queue->queuedata = lo;
528 /* queue parameters */
529 CLASSERT(PAGE_SIZE < (1 << (sizeof(unsigned short) * 8)));
530 blk_queue_logical_block_size(lo->lo_queue,
531 (unsigned short)PAGE_SIZE);
532 blk_queue_max_hw_sectors(lo->lo_queue,
533 LLOOP_MAX_SEGMENTS << (PAGE_SHIFT - 9));
534 blk_queue_max_segments(lo->lo_queue, LLOOP_MAX_SEGMENTS);
536 set_capacity(disks[lo->lo_number], size);
537 bd_set_size(bdev, size << 9);
539 set_blocksize(bdev, lo->lo_blocksize);
541 kthread_run(loop_thread, lo, "lloop%d", lo->lo_number);
546 /* This is safe: open() is still holding a reference. */
547 module_put(THIS_MODULE);
551 static int loop_clr_fd(struct lloop_device *lo, struct block_device *bdev,
554 struct file *filp = lo->lo_backing_file;
555 gfp_t gfp = lo->old_gfp_mask;
557 if (lo->lo_state != LLOOP_BOUND)
560 if (lo->lo_refcnt > count) /* we needed one fd for the ioctl */
566 spin_lock_irq(&lo->lo_lock);
567 lo->lo_state = LLOOP_RUNDOWN;
568 spin_unlock_irq(&lo->lo_lock);
569 wake_up(&lo->lo_bh_wait);
572 lo->lo_backing_file = NULL;
573 lo->lo_device = NULL;
575 lo->lo_sizelimit = 0;
577 invalidate_bdev(bdev);
578 set_capacity(disks[lo->lo_number], 0);
579 bd_set_size(bdev, 0);
580 mapping_set_gfp_mask(filp->f_mapping, gfp);
581 lo->lo_state = LLOOP_UNBOUND;
583 /* This is safe: open() is still holding a reference. */
584 module_put(THIS_MODULE);
588 static int lo_open(struct block_device *bdev, fmode_t mode)
590 struct lloop_device *lo = bdev->bd_disk->private_data;
592 mutex_lock(&lo->lo_ctl_mutex);
594 mutex_unlock(&lo->lo_ctl_mutex);
599 static void lo_release(struct gendisk *disk, fmode_t mode)
601 struct lloop_device *lo = disk->private_data;
603 mutex_lock(&lo->lo_ctl_mutex);
605 mutex_unlock(&lo->lo_ctl_mutex);
608 /* lloop device node's ioctl function. */
609 static int lo_ioctl(struct block_device *bdev, fmode_t mode,
610 unsigned int cmd, unsigned long arg)
612 struct lloop_device *lo = bdev->bd_disk->private_data;
613 struct inode *inode = NULL;
616 mutex_lock(&lloop_mutex);
618 case LL_IOC_LLOOP_DETACH: {
619 err = loop_clr_fd(lo, bdev, 2);
621 blkdev_put(bdev, 0); /* grabbed in LLOOP_ATTACH */
625 case LL_IOC_LLOOP_INFO: {
628 if (!lo->lo_backing_file) {
633 inode = file_inode(lo->lo_backing_file);
634 if (lo->lo_state == LLOOP_BOUND)
635 fid = ll_i2info(inode)->lli_fid;
639 if (copy_to_user((void __user *)arg, &fid, sizeof(fid)))
648 mutex_unlock(&lloop_mutex);
653 static struct block_device_operations lo_fops = {
654 .owner = THIS_MODULE,
656 .release = lo_release,
660 /* dynamic iocontrol callback.
661 * This callback is registered in lloop_init and will be called by
664 * This is a llite regular file ioctl function. It takes the responsibility
665 * of attaching or detaching a file by a lloop's device number.
667 static enum llioc_iter lloop_ioctl(struct inode *unused, struct file *file,
668 unsigned int cmd, unsigned long arg,
669 void *magic, int *rcp)
671 struct lloop_device *lo = NULL;
672 struct block_device *bdev = NULL;
676 if (magic != ll_iocontrol_magic)
684 CWARN("Enter llop_ioctl\n");
686 mutex_lock(&lloop_mutex);
688 case LL_IOC_LLOOP_ATTACH: {
689 struct lloop_device *lo_free = NULL;
692 for (i = 0; i < max_loop; i++, lo = NULL) {
694 if (lo->lo_state == LLOOP_UNBOUND) {
699 if (file_inode(lo->lo_backing_file) == file_inode(file))
702 if (lo || !lo_free) {
708 dev = MKDEV(lloop_major, lo->lo_number);
710 /* quit if the used pointer is writable */
711 if (put_user((long)old_encode_dev(dev), (long __user *)arg)) {
716 bdev = blkdev_get_by_dev(dev, file->f_mode, NULL);
723 err = loop_set_fd(lo, NULL, bdev, file);
732 case LL_IOC_LLOOP_DETACH_BYDEV: {
735 dev = old_decode_dev(arg);
736 if (MAJOR(dev) != lloop_major) {
742 if (minor > max_loop - 1) {
747 lo = &loop_dev[minor];
748 if (lo->lo_state != LLOOP_BOUND) {
753 bdev = lo->lo_device;
754 err = loop_clr_fd(lo, bdev, 1);
756 blkdev_put(bdev, 0); /* grabbed in LLOOP_ATTACH */
767 mutex_unlock(&lloop_mutex);
774 static int __init lloop_init(void)
777 unsigned int cmdlist[] = {
779 LL_IOC_LLOOP_DETACH_BYDEV,
782 if (max_loop < 1 || max_loop > 256) {
783 max_loop = MAX_LOOP_DEFAULT;
784 CWARN("lloop: invalid max_loop (must be between 1 and 256), using default (%u)\n",
788 lloop_major = register_blkdev(0, "lloop");
792 CDEBUG(D_CONFIG, "registered lloop major %d with %u minors\n",
793 lloop_major, max_loop);
795 ll_iocontrol_magic = ll_iocontrol_register(lloop_ioctl, 2, cmdlist);
796 if (!ll_iocontrol_magic)
799 loop_dev = kcalloc(max_loop, sizeof(*loop_dev), GFP_KERNEL);
803 disks = kcalloc(max_loop, sizeof(*disks), GFP_KERNEL);
807 for (i = 0; i < max_loop; i++) {
808 disks[i] = alloc_disk(1);
813 mutex_init(&lloop_mutex);
815 for (i = 0; i < max_loop; i++) {
816 struct lloop_device *lo = &loop_dev[i];
817 struct gendisk *disk = disks[i];
819 lo->lo_queue = blk_alloc_queue(GFP_KERNEL);
823 mutex_init(&lo->lo_ctl_mutex);
824 sema_init(&lo->lo_sem, 0);
825 init_waitqueue_head(&lo->lo_bh_wait);
827 spin_lock_init(&lo->lo_lock);
828 disk->major = lloop_major;
829 disk->first_minor = i;
830 disk->fops = &lo_fops;
831 sprintf(disk->disk_name, "lloop%d", i);
832 disk->private_data = lo;
833 disk->queue = lo->lo_queue;
836 /* We cannot fail after we call this, so another loop!*/
837 for (i = 0; i < max_loop; i++)
843 blk_cleanup_queue(loop_dev[i].lo_queue);
852 unregister_blkdev(lloop_major, "lloop");
853 ll_iocontrol_unregister(ll_iocontrol_magic);
854 CERROR("lloop: ran out of memory\n");
858 static void lloop_exit(void)
862 ll_iocontrol_unregister(ll_iocontrol_magic);
863 for (i = 0; i < max_loop; i++) {
864 del_gendisk(disks[i]);
865 blk_cleanup_queue(loop_dev[i].lo_queue);
869 unregister_blkdev(lloop_major, "lloop");
875 module_param(max_loop, int, 0444);
876 MODULE_PARM_DESC(max_loop, "maximum of lloop_device");
877 MODULE_AUTHOR("OpenSFS, Inc. <http://www.lustre.org/>");
878 MODULE_DESCRIPTION("Lustre virtual block device");
879 MODULE_VERSION(LUSTRE_VERSION_STRING);
880 MODULE_LICENSE("GPL");
882 module_init(lloop_init);
883 module_exit(lloop_exit);