cregit-Linux how code gets into the kernel

Release 4.11 block/partition-generic.c

Directory: block
/*
 *  Code extracted from drivers/block/genhd.c
 *  Copyright (C) 1991-1998  Linus Torvalds
 *  Re-organised Feb 1998 Russell King
 *
 *  We now have independent partition support from the
 *  block drivers, which allows all the partition code to
 *  be grouped in one location, and it to be mostly self
 *  contained.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/kmod.h>
#include <linux/ctype.h>
#include <linux/genhd.h>
#include <linux/dax.h>
#include <linux/blktrace_api.h>

#include "partitions/check.h"

#ifdef CONFIG_BLK_DEV_MD
extern void md_autodetect_dev(dev_t dev);
#endif
 
/*
 * disk_name() is used by partition check code and the genhd driver.
 * It formats the devicename of the indicated disk into
 * the supplied buffer (of size at least 32), and returns
 * a pointer to that same buffer (for convenience).
 */


char *disk_name(struct gendisk *hd, int partno, char *buf) { if (!partno) snprintf(buf, BDEVNAME_SIZE, "%s", hd->disk_name); else if (isdigit(hd->disk_name[strlen(hd->disk_name)-1])) snprintf(buf, BDEVNAME_SIZE, "%sp%d", hd->disk_name, partno); else snprintf(buf, BDEVNAME_SIZE, "%s%d", hd->disk_name, partno); return buf; }

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const char *bdevname(struct block_device *bdev, char *buf) { return disk_name(bdev->bd_disk, bdev->bd_part->partno, buf); }

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EXPORT_SYMBOL(bdevname); /* * There's very little reason to use this, you should really * have a struct block_device just about everywhere and use * bdevname() instead. */
const char *__bdevname(dev_t dev, char *buffer) { scnprintf(buffer, BDEVNAME_SIZE, "unknown-block(%u,%u)", MAJOR(dev), MINOR(dev)); return buffer; }

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EXPORT_SYMBOL(__bdevname);
static ssize_t part_partition_show(struct device *dev, struct device_attribute *attr, char *buf) { struct hd_struct *p = dev_to_part(dev); return sprintf(buf, "%d\n", p->partno); }

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static ssize_t part_start_show(struct device *dev, struct device_attribute *attr, char *buf) { struct hd_struct *p = dev_to_part(dev); return sprintf(buf, "%llu\n",(unsigned long long)p->start_sect); }

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ssize_t part_size_show(struct device *dev, struct device_attribute *attr, char *buf) { struct hd_struct *p = dev_to_part(dev); return sprintf(buf, "%llu\n",(unsigned long long)part_nr_sects_read(p)); }

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static ssize_t part_ro_show(struct device *dev, struct device_attribute *attr, char *buf) { struct hd_struct *p = dev_to_part(dev); return sprintf(buf, "%d\n", p->policy ? 1 : 0); }

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static ssize_t part_alignment_offset_show(struct device *dev, struct device_attribute *attr, char *buf) { struct hd_struct *p = dev_to_part(dev); return sprintf(buf, "%llu\n", (unsigned long long)p->alignment_offset); }

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static ssize_t part_discard_alignment_show(struct device *dev, struct device_attribute *attr, char *buf) { struct hd_struct *p = dev_to_part(dev); return sprintf(buf, "%u\n", p->discard_alignment); }

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ssize_t part_stat_show(struct device *dev, struct device_attribute *attr, char *buf) { struct hd_struct *p = dev_to_part(dev); int cpu; cpu = part_stat_lock(); part_round_stats(cpu, p); part_stat_unlock(); return sprintf(buf, "%8lu %8lu %8llu %8u " "%8lu %8lu %8llu %8u " "%8u %8u %8u" "\n", part_stat_read(p, ios[READ]), part_stat_read(p, merges[READ]), (unsigned long long)part_stat_read(p, sectors[READ]), jiffies_to_msecs(part_stat_read(p, ticks[READ])), part_stat_read(p, ios[WRITE]), part_stat_read(p, merges[WRITE]), (unsigned long long)part_stat_read(p, sectors[WRITE]), jiffies_to_msecs(part_stat_read(p, ticks[WRITE])), part_in_flight(p), jiffies_to_msecs(part_stat_read(p, io_ticks)), jiffies_to_msecs(part_stat_read(p, time_in_queue))); }

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ssize_t part_inflight_show(struct device *dev, struct device_attribute *attr, char *buf) { struct hd_struct *p = dev_to_part(dev); return sprintf(buf, "%8u %8u\n", atomic_read(&p->in_flight[0]), atomic_read(&p->in_flight[1])); }

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#ifdef CONFIG_FAIL_MAKE_REQUEST
ssize_t part_fail_show(struct device *dev, struct device_attribute *attr, char *buf) { struct hd_struct *p = dev_to_part(dev); return sprintf(buf, "%d\n", p->make_it_fail); }

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ssize_t part_fail_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { struct hd_struct *p = dev_to_part(dev); int i; if (count > 0 && sscanf(buf, "%d", &i) > 0) p->make_it_fail = (i == 0) ? 0 : 1; return count; }

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#endif static DEVICE_ATTR(partition, S_IRUGO, part_partition_show, NULL); static DEVICE_ATTR(start, S_IRUGO, part_start_show, NULL); static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL); static DEVICE_ATTR(ro, S_IRUGO, part_ro_show, NULL); static DEVICE_ATTR(alignment_offset, S_IRUGO, part_alignment_offset_show, NULL); static DEVICE_ATTR(discard_alignment, S_IRUGO, part_discard_alignment_show, NULL); static DEVICE_ATTR(stat, S_IRUGO, part_stat_show, NULL); static DEVICE_ATTR(inflight, S_IRUGO, part_inflight_show, NULL); #ifdef CONFIG_FAIL_MAKE_REQUEST static struct device_attribute dev_attr_fail = __ATTR(make-it-fail, S_IRUGO|S_IWUSR, part_fail_show, part_fail_store); #endif static struct attribute *part_attrs[] = { &dev_attr_partition.attr, &dev_attr_start.attr, &dev_attr_size.attr, &dev_attr_ro.attr, &dev_attr_alignment_offset.attr, &dev_attr_discard_alignment.attr, &dev_attr_stat.attr, &dev_attr_inflight.attr, #ifdef CONFIG_FAIL_MAKE_REQUEST &dev_attr_fail.attr, #endif NULL }; static struct attribute_group part_attr_group = { .attrs = part_attrs, }; static const struct attribute_group *part_attr_groups[] = { &part_attr_group, #ifdef CONFIG_BLK_DEV_IO_TRACE &blk_trace_attr_group, #endif NULL };
static void part_release(struct device *dev) { struct hd_struct *p = dev_to_part(dev); blk_free_devt(dev->devt); hd_free_part(p); kfree(p); }

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static int part_uevent(struct device *dev, struct kobj_uevent_env *env) { struct hd_struct *part = dev_to_part(dev); add_uevent_var(env, "PARTN=%u", part->partno); if (part->info && part->info->volname[0]) add_uevent_var(env, "PARTNAME=%s", part->info->volname); return 0; }

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struct device_type part_type = { .name = "partition", .groups = part_attr_groups, .release = part_release, .uevent = part_uevent, };
static void delete_partition_rcu_cb(struct rcu_head *head) { struct hd_struct *part = container_of(head, struct hd_struct, rcu_head); part->start_sect = 0; part->nr_sects = 0; part_stat_set_all(part, 0); put_device(part_to_dev(part)); }

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void __delete_partition(struct percpu_ref *ref) { struct hd_struct *part = container_of(ref, struct hd_struct, ref); call_rcu(&part->rcu_head, delete_partition_rcu_cb); }

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void delete_partition(struct gendisk *disk, int partno) { struct disk_part_tbl *ptbl = disk->part_tbl; struct hd_struct *part; if (partno >= ptbl->len) return; part = ptbl->part[partno]; if (!part) return; rcu_assign_pointer(ptbl->part[partno], NULL); rcu_assign_pointer(ptbl->last_lookup, NULL); kobject_put(part->holder_dir); device_del(part_to_dev(part)); hd_struct_kill(part); }

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static ssize_t whole_disk_show(struct device *dev, struct device_attribute *attr, char *buf) { return 0; }

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static DEVICE_ATTR(whole_disk, S_IRUSR | S_IRGRP | S_IROTH, whole_disk_show, NULL);
struct hd_struct *add_partition(struct gendisk *disk, int partno, sector_t start, sector_t len, int flags, struct partition_meta_info *info) { struct hd_struct *p; dev_t devt = MKDEV(0, 0); struct device *ddev = disk_to_dev(disk); struct device *pdev; struct disk_part_tbl *ptbl; const char *dname; int err; err = disk_expand_part_tbl(disk, partno); if (err) return ERR_PTR(err); ptbl = disk->part_tbl; if (ptbl->part[partno]) return ERR_PTR(-EBUSY); p = kzalloc(sizeof(*p), GFP_KERNEL); if (!p) return ERR_PTR(-EBUSY); if (!init_part_stats(p)) { err = -ENOMEM; goto out_free; } seqcount_init(&p->nr_sects_seq); pdev = part_to_dev(p); p->start_sect = start; p->alignment_offset = queue_limit_alignment_offset(&disk->queue->limits, start); p->discard_alignment = queue_limit_discard_alignment(&disk->queue->limits, start); p->nr_sects = len; p->partno = partno; p->policy = get_disk_ro(disk); if (info) { struct partition_meta_info *pinfo = alloc_part_info(disk); if (!pinfo) goto out_free_stats; memcpy(pinfo, info, sizeof(*info)); p->info = pinfo; } dname = dev_name(ddev); if (isdigit(dname[strlen(dname) - 1])) dev_set_name(pdev, "%sp%d", dname, partno); else dev_set_name(pdev, "%s%d", dname, partno); device_initialize(pdev); pdev->class = &block_class; pdev->type = &part_type; pdev->parent = ddev; err = blk_alloc_devt(p, &devt); if (err) goto out_free_info; pdev->devt = devt; /* delay uevent until 'holders' subdir is created */ dev_set_uevent_suppress(pdev, 1); err = device_add(pdev); if (err) goto out_put; err = -ENOMEM; p->holder_dir = kobject_create_and_add("holders", &pdev->kobj); if (!p->holder_dir) goto out_del; dev_set_uevent_suppress(pdev, 0); if (flags & ADDPART_FLAG_WHOLEDISK) { err = device_create_file(pdev, &dev_attr_whole_disk); if (err) goto out_del; } err = hd_ref_init(p); if (err) { if (flags & ADDPART_FLAG_WHOLEDISK) goto out_remove_file; goto out_del; } /* everything is up and running, commence */ rcu_assign_pointer(ptbl->part[partno], p); /* suppress uevent if the disk suppresses it */ if (!dev_get_uevent_suppress(ddev)) kobject_uevent(&pdev->kobj, KOBJ_ADD); return p; out_free_info: free_part_info(p); out_free_stats: free_part_stats(p); out_free: kfree(p); return ERR_PTR(err); out_remove_file: device_remove_file(pdev, &dev_attr_whole_disk); out_del: kobject_put(p->holder_dir); device_del(pdev); out_put: put_device(pdev); blk_free_devt(devt); return ERR_PTR(err); }

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static bool disk_unlock_native_capacity(struct gendisk *disk) { const struct block_device_operations *bdops = disk->fops; if (bdops->unlock_native_capacity && !(disk->flags & GENHD_FL_NATIVE_CAPACITY)) { printk(KERN_CONT "enabling native capacity\n"); bdops->unlock_native_capacity(disk); disk->flags |= GENHD_FL_NATIVE_CAPACITY; return true; } else { printk(KERN_CONT "truncated\n"); return false; } }

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static int drop_partitions(struct gendisk *disk, struct block_device *bdev) { struct disk_part_iter piter; struct hd_struct *part; int res; if (bdev->bd_part_count || bdev->bd_super) return -EBUSY; res = invalidate_partition(disk, 0); if (res) return res; disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY); while ((part = disk_part_iter_next(&piter))) delete_partition(disk, part->partno); disk_part_iter_exit(&piter); return 0; }

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static bool part_zone_aligned(struct gendisk *disk, struct block_device *bdev, sector_t from, sector_t size) { unsigned int zone_sectors = bdev_zone_sectors(bdev); /* * If this function is called, then the disk is a zoned block device * (host-aware or host-managed). This can be detected even if the * zoned block device support is disabled (CONFIG_BLK_DEV_ZONED not * set). In this case, however, only host-aware devices will be seen * as a block device is not created for host-managed devices. Without * zoned block device support, host-aware drives can still be used as * regular block devices (no zone operation) and their zone size will * be reported as 0. Allow this case. */ if (!zone_sectors) return true; /* * Check partition start and size alignement. If the drive has a * smaller last runt zone, ignore it and allow the partition to * use it. Check the zone size too: it should be a power of 2 number * of sectors. */ if (WARN_ON_ONCE(!is_power_of_2(zone_sectors))) { u32 rem; div_u64_rem(from, zone_sectors, &rem); if (rem) return false; if ((from + size) < get_capacity(disk)) { div_u64_rem(size, zone_sectors, &rem); if (rem) return false; } } else { if (from & (zone_sectors - 1)) return false; if ((from + size) < get_capacity(disk) && (size & (zone_sectors - 1))) return false; } return true; }

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int rescan_partitions(struct gendisk *disk, struct block_device *bdev) { struct parsed_partitions *state = NULL; struct hd_struct *part; int p, highest, res; rescan: if (state && !IS_ERR(state)) { free_partitions(state); state = NULL; } res = drop_partitions(disk, bdev); if (res) return res; if (disk->fops->revalidate_disk) disk->fops->revalidate_disk(disk); blk_integrity_revalidate(disk); check_disk_size_change(disk, bdev); bdev->bd_invalidated = 0; if (!get_capacity(disk) || !(state = check_partition(disk, bdev))) return 0; if (IS_ERR(state)) { /* * I/O error reading the partition table. If any * partition code tried to read beyond EOD, retry * after unlocking native capacity. */ if (PTR_ERR(state) == -ENOSPC) { printk(KERN_WARNING "%s: partition table beyond EOD, ", disk->disk_name); if (disk_unlock_native_capacity(disk)) goto rescan; } return -EIO; } /* * If any partition code tried to read beyond EOD, try * unlocking native capacity even if partition table is * successfully read as we could be missing some partitions. */ if (state->access_beyond_eod) { printk(KERN_WARNING "%s: partition table partially beyond EOD, ", disk->disk_name); if (disk_unlock_native_capacity(disk)) goto rescan; } /* tell userspace that the media / partition table may have changed */ kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE); /* Detect the highest partition number and preallocate * disk->part_tbl. This is an optimization and not strictly * necessary. */ for (p = 1, highest = 0; p < state->limit; p++) if (state->parts[p].size) highest = p; disk_expand_part_tbl(disk, highest); /* add partitions */ for (p = 1; p < state->limit; p++) { sector_t size, from; size = state->parts[p].size; if (!size) continue; from = state->parts[p].from; if (from >= get_capacity(disk)) { printk(KERN_WARNING "%s: p%d start %llu is beyond EOD, ", disk->disk_name, p, (unsigned long long) from); if (disk_unlock_native_capacity(disk)) goto rescan; continue; } if (from + size > get_capacity(disk)) { printk(KERN_WARNING "%s: p%d size %llu extends beyond EOD, ", disk->disk_name, p, (unsigned long long) size); if (disk_unlock_native_capacity(disk)) { /* free state and restart */ goto rescan; } else { /* * we can not ignore partitions of broken tables * created by for example camera firmware, but * we limit them to the end of the disk to avoid * creating invalid block devices */ size = get_capacity(disk) - from; } } /* * On a zoned block device, partitions should be aligned on the * device zone size (i.e. zone boundary crossing not allowed). * Otherwise, resetting the write pointer of the last zone of * one partition may impact the following partition. */ if (bdev_is_zoned(bdev) && !part_zone_aligned(disk, bdev, from, size)) { printk(KERN_WARNING "%s: p%d start %llu+%llu is not zone aligned\n", disk->disk_name, p, (unsigned long long) from, (unsigned long long) size); continue; } part = add_partition(disk, p, from, size, state->parts[p].flags, &state->parts[p].info); if (IS_ERR(part)) { printk(KERN_ERR " %s: p%d could not be added: %ld\n", disk->disk_name, p, -PTR_ERR(part)); continue; } #ifdef CONFIG_BLK_DEV_MD if (state->parts[p].flags & ADDPART_FLAG_RAID) md_autodetect_dev(part_to_dev(part)->devt); #endif } free_partitions(state); return 0; }

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int invalidate_partitions(struct gendisk *disk, struct block_device *bdev) { int res; if (!bdev->bd_invalidated) return 0; res = drop_partitions(disk, bdev); if (res) return res; set_capacity(disk, 0); check_disk_size_change(disk, bdev); bdev->bd_invalidated = 0; /* tell userspace that the media / partition table may have changed */ kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE); return 0; }

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static struct page *read_pagecache_sector(struct block_device *bdev, sector_t n) { struct address_space *mapping = bdev->bd_inode->i_mapping; return read_mapping_page(mapping, (pgoff_t)(n >> (PAGE_SHIFT-9)), NULL); }

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unsigned char *read_dev_sector