// SPDX-License-Identifier: GPL-2.0-only/* * Copyright 1993 by Theodore Ts'o. */#include <linux/module.h>#include <linux/moduleparam.h>#include <linux/sched.h>#include <linux/fs.h>#include <linux/pagemap.h>#include <linux/file.h>#include <linux/stat.h>#include <linux/errno.h>#include <linux/major.h>#include <linux/wait.h>#include <linux/blkpg.h>#include <linux/init.h>#include <linux/swap.h>#include <linux/slab.h>#include <linux/compat.h>#include <linux/suspend.h>#include <linux/freezer.h>#include <linux/mutex.h>#include <linux/writeback.h>#include <linux/completion.h>#include <linux/highmem.h>#include <linux/splice.h>#include <linux/sysfs.h>#include <linux/miscdevice.h>#include <linux/falloc.h>#include <linux/uio.h>#include <linux/ioprio.h>#include <linux/blk-cgroup.h>#include <linux/sched/mm.h>#include <linux/statfs.h>#include <linux/uaccess.h>#include <linux/blk-mq.h>#include <linux/spinlock.h>#include <uapi/linux/loop.h> /* Possible states of device */enum { Lo_unbound, Lo_bound, Lo_rundown, Lo_deleting,}; struct loop_func_table; struct loop_device { int lo_number; loff_t lo_offset; loff_t lo_sizelimit; int lo_flags; char lo_file_name[LO_NAME_SIZE]; struct file * lo_backing_file; struct block_device *lo_device; gfp_t old_gfp_mask; spinlock_t lo_lock; int lo_state; spinlock_t lo_work_lock; struct workqueue_struct *workqueue; struct work_struct rootcg_work; struct list_head rootcg_cmd_list; struct list_head idle_worker_list; struct rb_root worker_tree; struct timer_list timer; bool use_dio; bool sysfs_inited; struct request_queue *lo_queue; struct blk_mq_tag_set tag_set; struct gendisk *lo_disk; struct mutex lo_mutex; bool idr_visible;}; struct loop_cmd { struct list_head list_entry; bool use_aio; /* use AIO interface to handle I/O */ atomic_t ref; /* only for aio */ long ret; struct kiocb iocb; struct bio_vec *bvec; struct cgroup_subsys_state *blkcg_css; struct cgroup_subsys_state *memcg_css;}; #define LOOP_IDLE_WORKER_TIMEOUT (60 * HZ)#define LOOP_DEFAULT_HW_Q_DEPTH (128) static DEFINE_IDR(loop_index_idr);static DEFINE_MUTEX(loop_ctl_mutex);static DEFINE_MUTEX(loop_validate_mutex); /** * loop_global_lock_killable() - take locks for safe loop_validate_file() test * * @lo: struct loop_device * @global: true if @lo is about to bind another "struct loop_device", false otherwise * * Returns 0 on success, -EINTR otherwise. * * Since loop_validate_file() traverses on other "struct loop_device" if * is_loop_device() is true, we need a global lock for serializing concurrent * loop_configure()/loop_change_fd()/__loop_clr_fd() calls. */static int loop_global_lock_killable(struct loop_device *lo, bool global){ int err; if (global) { err = mutex_lock_killable(&loop_validate_mutex); if (err) return err; } err = mutex_lock_killable(&lo->lo_mutex); if (err && global) mutex_unlock(&loop_validate_mutex); return err;} /** * loop_global_unlock() - release locks taken by loop_global_lock_killable() * * @lo: struct loop_device * @global: true if @lo was about to bind another "struct loop_device", false otherwise */static void loop_global_unlock(struct loop_device *lo, bool global){ mutex_unlock(&lo->lo_mutex); if (global) mutex_unlock(&loop_validate_mutex);} static int max_part;static int part_shift; static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file){ loff_t loopsize; /* Compute loopsize in bytes */ loopsize = i_size_read(file->f_mapping->host); if (offset > 0) loopsize -= offset; /* offset is beyond i_size, weird but possible */ if (loopsize < 0) return 0; if (sizelimit > 0 && sizelimit < loopsize) loopsize = sizelimit; /* * Unfortunately, if we want to do I/O on the device, * the number of 512-byte sectors has to fit into a sector_t. */ return loopsize >> 9;} static loff_t get_loop_size(struct loop_device *lo, struct file *file){ return get_size(lo->lo_offset, lo->lo_sizelimit, file);} static void __loop_update_dio(struct loop_device *lo, bool dio){ struct file *file = lo->lo_backing_file; struct address_space *mapping = file->f_mapping; struct inode *inode = mapping->host; unsigned short sb_bsize = 0; unsigned dio_align = 0; bool use_dio; if (inode->i_sb->s_bdev) { sb_bsize = bdev_logical_block_size(inode->i_sb->s_bdev); dio_align = sb_bsize - 1; } /* * We support direct I/O only if lo_offset is aligned with the * logical I/O size of backing device, and the logical block * size of loop is bigger than the backing device's. * * TODO: the above condition may be loosed in the future, and * direct I/O may be switched runtime at that time because most * of requests in sane applications should be PAGE_SIZE aligned */ if (dio) { if (queue_logical_block_size(lo->lo_queue) >= sb_bsize && !(lo->lo_offset & dio_align) && (file->f_mode & FMODE_CAN_ODIRECT)) use_dio = true; else use_dio = false; } else { use_dio = false; } if (lo->use_dio == use_dio) return; /* flush dirty pages before changing direct IO */ vfs_fsync(file, 0); /* * The flag of LO_FLAGS_DIRECT_IO is handled similarly with * LO_FLAGS_READ_ONLY, both are set from kernel, and losetup * will get updated by ioctl(LOOP_GET_STATUS) */ if (lo->lo_state == Lo_bound) blk_mq_freeze_queue(lo->lo_queue); lo->use_dio = use_dio; if (use_dio) { blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, lo->lo_queue); lo->lo_flags |= LO_FLAGS_DIRECT_IO; } else { blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue); lo->lo_flags &= ~LO_FLAGS_DIRECT_IO; } if (lo->lo_state == Lo_bound) blk_mq_unfreeze_queue(lo->lo_queue);} /** * loop_set_size() - sets device size and notifies userspace * @lo: struct loop_device to set the size for * @size: new size of the loop device * * Callers must validate that the size passed into this function fits into * a sector_t, eg using loop_validate_size() */static void loop_set_size(struct loop_device *lo, loff_t size){ if (!set_capacity_and_notify(lo->lo_disk, size)) kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE);} static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos){ struct iov_iter i; ssize_t bw; iov_iter_bvec(&i, WRITE, bvec, 1, bvec->bv_len); file_start_write(file); bw = vfs_iter_write(file, &i, ppos, 0); file_end_write(file); if (likely(bw == bvec->bv_len)) return 0; printk_ratelimited(KERN_ERR "loop: Write error at byte offset %llu, length %i.\n", (unsigned long long)*ppos, bvec->bv_len); if (bw >= 0) bw = -EIO; return bw;} static int lo_write_simple(struct loop_device *lo, struct request *rq, loff_t pos){ struct bio_vec bvec; struct req_iterator iter; int ret = 0; rq_for_each_segment(bvec, rq, iter) { ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos); if (ret < 0) break; cond_resched(); } return ret;} static int lo_read_simple(struct loop_device *lo, struct request *rq, loff_t pos){ struct bio_vec bvec; struct req_iterator iter; struct iov_iter i; ssize_t len; rq_for_each_segment(bvec, rq, iter) { iov_iter_bvec(&i, READ, &bvec, 1, bvec.bv_len); len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0); if (len < 0) return len; flush_dcache_page(bvec.bv_page); if (len != bvec.bv_len) { struct bio *bio; __rq_for_each_bio(bio, rq) zero_fill_bio(bio); break; } cond_resched(); } return 0;} static int lo_fallocate(struct loop_device *lo, struct request *rq, loff_t pos, int mode){ /* * We use fallocate to manipulate the space mappings used by the image * a.k.a. discard/zerorange. */ struct file *file = lo->lo_backing_file; int ret; mode |= FALLOC_FL_KEEP_SIZE; if (!bdev_max_discard_sectors(lo->lo_device)) return -EOPNOTSUPP; ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq)); if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP)) return -EIO; return ret;} static int lo_req_flush(struct loop_device *lo, struct request *rq){ int ret = vfs_fsync(lo->lo_backing_file, 0); if (unlikely(ret && ret != -EINVAL)) ret = -EIO; return ret;} static void lo_complete_rq(struct request *rq){ struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); blk_status_t ret = BLK_STS_OK; if (!cmd->use_aio || cmd->ret < 0 || cmd->ret == blk_rq_bytes(rq) || req_op(rq) != REQ_OP_READ) { if (cmd->ret < 0) ret = errno_to_blk_status(cmd->ret); goto end_io; } /* * Short READ - if we got some data, advance our request and * retry it. If we got no data, end the rest with EIO. */ if (cmd->ret) { blk_update_request(rq, BLK_STS_OK, cmd->ret); cmd->ret = 0; blk_mq_requeue_request(rq, true); } else { if (cmd->use_aio) { struct bio *bio = rq->bio; while (bio) { zero_fill_bio(bio); bio = bio->bi_next; } } ret = BLK_STS_IOERR;end_io: blk_mq_end_request(rq, ret); }} static void lo_rw_aio_do_completion(struct loop_cmd *cmd){ struct request *rq = blk_mq_rq_from_pdu(cmd); if (!atomic_dec_and_test(&cmd->ref)) return; kfree(cmd->bvec); cmd->bvec = NULL; if (likely(!blk_should_fake_timeout(rq->q))) blk_mq_complete_request(rq);} static void lo_rw_aio_complete(struct kiocb *iocb, long ret){ struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb); cmd->ret = ret; lo_rw_aio_do_completion(cmd);} static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, loff_t pos, bool rw){ struct iov_iter iter; struct req_iterator rq_iter; struct bio_vec *bvec; struct request *rq = blk_mq_rq_from_pdu(cmd); struct bio *bio = rq->bio; struct file *file = lo->lo_backing_file; struct bio_vec tmp; unsigned int offset; int nr_bvec = 0; int ret; rq_for_each_bvec(tmp, rq, rq_iter) nr_bvec++; if (rq->bio != rq->biotail) { bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec), GFP_NOIO); if (!bvec) return -EIO; cmd->bvec = bvec; /* * The bios of the request may be started from the middle of * the 'bvec' because of bio splitting, so we can't directly * copy bio->bi_iov_vec to new bvec. The rq_for_each_bvec * API will take care of all details for us. */ rq_for_each_bvec(tmp, rq, rq_iter) { *bvec = tmp; bvec++; } bvec = cmd->bvec; offset = 0; } else { /* * Same here, this bio may be started from the middle of the * 'bvec' because of bio splitting, so offset from the bvec * must be passed to iov iterator */ offset = bio->bi_iter.bi_bvec_done; bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); } atomic_set(&cmd->ref, 2); iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq)); iter.iov_offset = offset; cmd->iocb.ki_pos = pos; cmd->iocb.ki_filp = file; cmd->iocb.ki_complete = lo_rw_aio_complete; cmd->iocb.ki_flags = IOCB_DIRECT; cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0); if (rw == WRITE) ret = call_write_iter(file, &cmd->iocb, &iter); else ret = call_read_iter(file, &cmd->iocb, &iter); lo_rw_aio_do_completion(cmd); if (ret != -EIOCBQUEUED) lo_rw_aio_complete(&cmd->iocb, ret); return 0;} static int do_req_filebacked(struct loop_device *lo, struct request *rq){ struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset; /* * lo_write_simple and lo_read_simple should have been covered * by io submit style function like lo_rw_aio(), one blocker * is that lo_read_simple() need to call flush_dcache_page after * the page is written from kernel, and it isn't easy to handle * this in io submit style function which submits all segments * of the req at one time. And direct read IO doesn't need to * run flush_dcache_page(). */ switch (req_op(rq)) { case REQ_OP_FLUSH: return lo_req_flush(lo, rq); case REQ_OP_WRITE_ZEROES: /* * If the caller doesn't want deallocation, call zeroout to * write zeroes the range. Otherwise, punch them out. */ return lo_fallocate(lo, rq, pos, (rq->cmd_flags & REQ_NOUNMAP) ? FALLOC_FL_ZERO_RANGE : FALLOC_FL_PUNCH_HOLE); case REQ_OP_DISCARD: return lo_fallocate(lo, rq, pos, FALLOC_FL_PUNCH_HOLE); case REQ_OP_WRITE: if (cmd->use_aio) return lo_rw_aio(lo, cmd, pos, WRITE); else return lo_write_simple(lo, rq, pos); case REQ_OP_READ: if (cmd->use_aio) return lo_rw_aio(lo, cmd, pos, READ); else return lo_read_simple(lo, rq, pos);Lines 1–500 of 2275. Load more
// SPDX-License-Identifier: GPL-2.0-only /* * Copyright 1993 by Theodore Ts'o. */ #include <linux/module.h> #include <linux/moduleparam.h> #include <linux/sched.h> #include <linux/fs.h> #include <linux/pagemap.h> #include <linux/file.h> #include <linux/stat.h> #include <linux/errno.h> #include <linux/major.h> #include <linux/wait.h> #include <linux/blkpg.h> #include <linux/init.h> #include <linux/swap.h> #include <linux/slab.h> #include <linux/compat.h> #include <linux/suspend.h> #include <linux/freezer.h> #include <linux/mutex.h> #include <linux/writeback.h> #include <linux/completion.h> #include <linux/highmem.h> #include <linux/splice.h> #include <linux/sysfs.h> #include <linux/miscdevice.h> #include <linux/falloc.h> #include <linux/uio.h> #include <linux/ioprio.h> #include <linux/blk-cgroup.h> #include <linux/sched/mm.h> #include <linux/statfs.h> #include <linux/uaccess.h> #include <linux/blk-mq.h> #include <linux/spinlock.h> #include <uapi/linux/loop.h> /* Possible states of device */ enum { Lo_unbound, Lo_bound, Lo_rundown, Lo_deleting, }; struct loop_func_table; struct loop_device { int lo_number; loff_t lo_offset; loff_t lo_sizelimit; int lo_flags; char lo_file_name[LO_NAME_SIZE]; struct file * lo_backing_file; struct block_device *lo_device; gfp_t old_gfp_mask; spinlock_t lo_lock; int lo_state; spinlock_t lo_work_lock; struct workqueue_struct *workqueue; struct work_struct rootcg_work; struct list_head rootcg_cmd_list; struct list_head idle_worker_list; struct rb_root worker_tree; struct timer_list timer; bool use_dio; bool sysfs_inited; struct request_queue *lo_queue; struct blk_mq_tag_set tag_set; struct gendisk *lo_disk; struct mutex lo_mutex; bool idr_visible; }; struct loop_cmd { struct list_head list_entry; bool use_aio; /* use AIO interface to handle I/O */ atomic_t ref; /* only for aio */ long ret; struct kiocb iocb; struct bio_vec *bvec; struct cgroup_subsys_state *blkcg_css; struct cgroup_subsys_state *memcg_css; }; #define LOOP_IDLE_WORKER_TIMEOUT (60 * HZ) #define LOOP_DEFAULT_HW_Q_DEPTH (128) static DEFINE_IDR(loop_index_idr); static DEFINE_MUTEX(loop_ctl_mutex); static DEFINE_MUTEX(loop_validate_mutex); /** * loop_global_lock_killable() - take locks for safe loop_validate_file() test * * @lo: struct loop_device * @global: true if @lo is about to bind another "struct loop_device", false otherwise * * Returns 0 on success, -EINTR otherwise. * * Since loop_validate_file() traverses on other "struct loop_device" if * is_loop_device() is true, we need a global lock for serializing concurrent * loop_configure()/loop_change_fd()/__loop_clr_fd() calls. */ static int loop_global_lock_killable(struct loop_device *lo, bool global) { int err; if (global) { err = mutex_lock_killable(&loop_validate_mutex); if (err) return err; } err = mutex_lock_killable(&lo->lo_mutex); if (err && global) mutex_unlock(&loop_validate_mutex); return err; } /** * loop_global_unlock() - release locks taken by loop_global_lock_killable() * * @lo: struct loop_device * @global: true if @lo was about to bind another "struct loop_device", false otherwise */ static void loop_global_unlock(struct loop_device *lo, bool global) { mutex_unlock(&lo->lo_mutex); if (global) mutex_unlock(&loop_validate_mutex); } static int max_part; static int part_shift; static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file) { loff_t loopsize; /* Compute loopsize in bytes */ loopsize = i_size_read(file->f_mapping->host); if (offset > 0) loopsize -= offset; /* offset is beyond i_size, weird but possible */ if (loopsize < 0) return 0; if (sizelimit > 0 && sizelimit < loopsize) loopsize = sizelimit; /* * Unfortunately, if we want to do I/O on the device, * the number of 512-byte sectors has to fit into a sector_t. */ return loopsize >> 9; } static loff_t get_loop_size(struct loop_device *lo, struct file *file) { return get_size(lo->lo_offset, lo->lo_sizelimit, file); } static void __loop_update_dio(struct loop_device *lo, bool dio) { struct file *file = lo->lo_backing_file; struct address_space *mapping = file->f_mapping; struct inode *inode = mapping->host; unsigned short sb_bsize = 0; unsigned dio_align = 0; bool use_dio; if (inode->i_sb->s_bdev) { sb_bsize = bdev_logical_block_size(inode->i_sb->s_bdev); dio_align = sb_bsize - 1; } /* * We support direct I/O only if lo_offset is aligned with the * logical I/O size of backing device, and the logical block * size of loop is bigger than the backing device's. * * TODO: the above condition may be loosed in the future, and * direct I/O may be switched runtime at that time because most * of requests in sane applications should be PAGE_SIZE aligned */ if (dio) { if (queue_logical_block_size(lo->lo_queue) >= sb_bsize && !(lo->lo_offset & dio_align) && (file->f_mode & FMODE_CAN_ODIRECT)) use_dio = true; else use_dio = false; } else { use_dio = false; } if (lo->use_dio == use_dio) return; /* flush dirty pages before changing direct IO */ vfs_fsync(file, 0); /* * The flag of LO_FLAGS_DIRECT_IO is handled similarly with * LO_FLAGS_READ_ONLY, both are set from kernel, and losetup * will get updated by ioctl(LOOP_GET_STATUS) */ if (lo->lo_state == Lo_bound) blk_mq_freeze_queue(lo->lo_queue); lo->use_dio = use_dio; if (use_dio) { blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, lo->lo_queue); lo->lo_flags |= LO_FLAGS_DIRECT_IO; } else { blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue); lo->lo_flags &= ~LO_FLAGS_DIRECT_IO; } if (lo->lo_state == Lo_bound) blk_mq_unfreeze_queue(lo->lo_queue); } /** * loop_set_size() - sets device size and notifies userspace * @lo: struct loop_device to set the size for * @size: new size of the loop device * * Callers must validate that the size passed into this function fits into * a sector_t, eg using loop_validate_size() */ static void loop_set_size(struct loop_device *lo, loff_t size) { if (!set_capacity_and_notify(lo->lo_disk, size)) kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE); } static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos) { struct iov_iter i; ssize_t bw; iov_iter_bvec(&i, WRITE, bvec, 1, bvec->bv_len); file_start_write(file); bw = vfs_iter_write(file, &i, ppos, 0); file_end_write(file); if (likely(bw == bvec->bv_len)) return 0; printk_ratelimited(KERN_ERR "loop: Write error at byte offset %llu, length %i.\n", (unsigned long long)*ppos, bvec->bv_len); if (bw >= 0) bw = -EIO; return bw; } static int lo_write_simple(struct loop_device *lo, struct request *rq, loff_t pos) { struct bio_vec bvec; struct req_iterator iter; int ret = 0; rq_for_each_segment(bvec, rq, iter) { ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos); if (ret < 0) break; cond_resched(); } return ret; } static int lo_read_simple(struct loop_device *lo, struct request *rq, loff_t pos) { struct bio_vec bvec; struct req_iterator iter; struct iov_iter i; ssize_t len; rq_for_each_segment(bvec, rq, iter) { iov_iter_bvec(&i, READ, &bvec, 1, bvec.bv_len); len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0); if (len < 0) return len; flush_dcache_page(bvec.bv_page); if (len != bvec.bv_len) { struct bio *bio; __rq_for_each_bio(bio, rq) zero_fill_bio(bio); break; } cond_resched(); } return 0; } static int lo_fallocate(struct loop_device *lo, struct request *rq, loff_t pos, int mode) { /* * We use fallocate to manipulate the space mappings used by the image * a.k.a. discard/zerorange. */ struct file *file = lo->lo_backing_file; int ret; mode |= FALLOC_FL_KEEP_SIZE; if (!bdev_max_discard_sectors(lo->lo_device)) return -EOPNOTSUPP; ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq)); if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP)) return -EIO; return ret; } static int lo_req_flush(struct loop_device *lo, struct request *rq) { int ret = vfs_fsync(lo->lo_backing_file, 0); if (unlikely(ret && ret != -EINVAL)) ret = -EIO; return ret; } static void lo_complete_rq(struct request *rq) { struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); blk_status_t ret = BLK_STS_OK; if (!cmd->use_aio || cmd->ret < 0 || cmd->ret == blk_rq_bytes(rq) || req_op(rq) != REQ_OP_READ) { if (cmd->ret < 0) ret = errno_to_blk_status(cmd->ret); goto end_io; } /* * Short READ - if we got some data, advance our request and * retry it. If we got no data, end the rest with EIO. */ if (cmd->ret) { blk_update_request(rq, BLK_STS_OK, cmd->ret); cmd->ret = 0; blk_mq_requeue_request(rq, true); } else { if (cmd->use_aio) { struct bio *bio = rq->bio; while (bio) { zero_fill_bio(bio); bio = bio->bi_next; } } ret = BLK_STS_IOERR; end_io: blk_mq_end_request(rq, ret); } } static void lo_rw_aio_do_completion(struct loop_cmd *cmd) { struct request *rq = blk_mq_rq_from_pdu(cmd); if (!atomic_dec_and_test(&cmd->ref)) return; kfree(cmd->bvec); cmd->bvec = NULL; if (likely(!blk_should_fake_timeout(rq->q))) blk_mq_complete_request(rq); } static void lo_rw_aio_complete(struct kiocb *iocb, long ret) { struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb); cmd->ret = ret; lo_rw_aio_do_completion(cmd); } static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, loff_t pos, bool rw) { struct iov_iter iter; struct req_iterator rq_iter; struct bio_vec *bvec; struct request *rq = blk_mq_rq_from_pdu(cmd); struct bio *bio = rq->bio; struct file *file = lo->lo_backing_file; struct bio_vec tmp; unsigned int offset; int nr_bvec = 0; int ret; rq_for_each_bvec(tmp, rq, rq_iter) nr_bvec++; if (rq->bio != rq->biotail) { bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec), GFP_NOIO); if (!bvec) return -EIO; cmd->bvec = bvec; /* * The bios of the request may be started from the middle of * the 'bvec' because of bio splitting, so we can't directly * copy bio->bi_iov_vec to new bvec. The rq_for_each_bvec * API will take care of all details for us. */ rq_for_each_bvec(tmp, rq, rq_iter) { *bvec = tmp; bvec++; } bvec = cmd->bvec; offset = 0; } else { /* * Same here, this bio may be started from the middle of the * 'bvec' because of bio splitting, so offset from the bvec * must be passed to iov iterator */ offset = bio->bi_iter.bi_bvec_done; bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); } atomic_set(&cmd->ref, 2); iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq)); iter.iov_offset = offset; cmd->iocb.ki_pos = pos; cmd->iocb.ki_filp = file; cmd->iocb.ki_complete = lo_rw_aio_complete; cmd->iocb.ki_flags = IOCB_DIRECT; cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0); if (rw == WRITE) ret = call_write_iter(file, &cmd->iocb, &iter); else ret = call_read_iter(file, &cmd->iocb, &iter); lo_rw_aio_do_completion(cmd); if (ret != -EIOCBQUEUED) lo_rw_aio_complete(&cmd->iocb, ret); return 0; } static int do_req_filebacked(struct loop_device *lo, struct request *rq) { struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset; /* * lo_write_simple and lo_read_simple should have been covered * by io submit style function like lo_rw_aio(), one blocker * is that lo_read_simple() need to call flush_dcache_page after * the page is written from kernel, and it isn't easy to handle * this in io submit style function which submits all segments * of the req at one time. And direct read IO doesn't need to * run flush_dcache_page(). */ switch (req_op(rq)) { case REQ_OP_FLUSH: return lo_req_flush(lo, rq); case REQ_OP_WRITE_ZEROES: /* * If the caller doesn't want deallocation, call zeroout to * write zeroes the range. Otherwise, punch them out. */ return lo_fallocate(lo, rq, pos, (rq->cmd_flags & REQ_NOUNMAP) ? FALLOC_FL_ZERO_RANGE : FALLOC_FL_PUNCH_HOLE); case REQ_OP_DISCARD: return lo_fallocate(lo, rq, pos, FALLOC_FL_PUNCH_HOLE); case REQ_OP_WRITE: if (cmd->use_aio) return lo_rw_aio(lo, cmd, pos, WRITE); else return lo_write_simple(lo, rq, pos); case REQ_OP_READ: if (cmd->use_aio) return lo_rw_aio(lo, cmd, pos, READ); else return lo_read_simple(lo, rq, pos);