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![Matthew Wilcox (Oracle)](/assets/img/avatar_default.png)
My UEK-derived config has 1030 files depending on pagemap.h before this change. Afterwards, just 326 files need to be rebuilt when I touch pagemap.h. I think blkdev.h is probably included too widely, but untangling that dependency is harder and this solves my problem. x86 allmodconfig builds, but there may be implicit include problems on other architectures. Link: https://lkml.kernel.org/r/20210309195747.283796-1-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Acked-by: Dan Williams <dan.j.williams@intel.com> [nvdimm] Acked-by: Jens Axboe <axboe@kernel.dk> [block] Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: Coly Li <colyli@suse.de> [bcache] Acked-by: Martin K. Petersen <martin.petersen@oracle.com> [scsi] Reviewed-by: William Kucharski <william.kucharski@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
259 lines
7.6 KiB
C
259 lines
7.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* scsicam.c - SCSI CAM support functions, use for HDIO_GETGEO, etc.
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*
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* Copyright 1993, 1994 Drew Eckhardt
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* Visionary Computing
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* (Unix and Linux consulting and custom programming)
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* drew@Colorado.EDU
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* +1 (303) 786-7975
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*
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* For more information, please consult the SCSI-CAM draft.
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*/
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/fs.h>
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#include <linux/genhd.h>
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#include <linux/kernel.h>
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#include <linux/blkdev.h>
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#include <linux/pagemap.h>
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#include <linux/msdos_partition.h>
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#include <asm/unaligned.h>
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#include <scsi/scsicam.h>
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/**
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* scsi_bios_ptable - Read PC partition table out of first sector of device.
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* @dev: from this device
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*
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* Description: Reads the first sector from the device and returns %0x42 bytes
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* starting at offset %0x1be.
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* Returns: partition table in kmalloc(GFP_KERNEL) memory, or NULL on error.
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*/
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unsigned char *scsi_bios_ptable(struct block_device *dev)
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{
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struct address_space *mapping = bdev_whole(dev)->bd_inode->i_mapping;
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unsigned char *res = NULL;
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struct page *page;
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page = read_mapping_page(mapping, 0, NULL);
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if (IS_ERR(page))
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return NULL;
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if (!PageError(page))
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res = kmemdup(page_address(page) + 0x1be, 66, GFP_KERNEL);
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put_page(page);
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return res;
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}
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EXPORT_SYMBOL(scsi_bios_ptable);
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/**
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* scsi_partsize - Parse cylinders/heads/sectors from PC partition table
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* @bdev: block device to parse
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* @capacity: size of the disk in sectors
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* @geom: output in form of [hds, cylinders, sectors]
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*
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* Determine the BIOS mapping/geometry used to create the partition
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* table, storing the results in @geom.
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*
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* Returns: %false on failure, %true on success.
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*/
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bool scsi_partsize(struct block_device *bdev, sector_t capacity, int geom[3])
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{
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int cyl, ext_cyl, end_head, end_cyl, end_sector;
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unsigned int logical_end, physical_end, ext_physical_end;
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struct msdos_partition *p, *largest = NULL;
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void *buf;
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int ret = false;
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buf = scsi_bios_ptable(bdev);
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if (!buf)
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return false;
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if (*(unsigned short *) (buf + 64) == 0xAA55) {
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int largest_cyl = -1, i;
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for (i = 0, p = buf; i < 4; i++, p++) {
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if (!p->sys_ind)
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continue;
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#ifdef DEBUG
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printk("scsicam_bios_param : partition %d has system \n",
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i);
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#endif
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cyl = p->cyl + ((p->sector & 0xc0) << 2);
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if (cyl > largest_cyl) {
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largest_cyl = cyl;
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largest = p;
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}
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}
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}
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if (largest) {
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end_cyl = largest->end_cyl + ((largest->end_sector & 0xc0) << 2);
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end_head = largest->end_head;
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end_sector = largest->end_sector & 0x3f;
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if (end_head + 1 == 0 || end_sector == 0)
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goto out_free_buf;
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#ifdef DEBUG
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printk("scsicam_bios_param : end at h = %d, c = %d, s = %d\n",
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end_head, end_cyl, end_sector);
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#endif
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physical_end = end_cyl * (end_head + 1) * end_sector +
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end_head * end_sector + end_sector;
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/* This is the actual _sector_ number at the end */
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logical_end = get_unaligned_le32(&largest->start_sect)
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+ get_unaligned_le32(&largest->nr_sects);
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/* This is for >1023 cylinders */
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ext_cyl = (logical_end - (end_head * end_sector + end_sector))
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/ (end_head + 1) / end_sector;
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ext_physical_end = ext_cyl * (end_head + 1) * end_sector +
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end_head * end_sector + end_sector;
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#ifdef DEBUG
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printk("scsicam_bios_param : logical_end=%d physical_end=%d ext_physical_end=%d ext_cyl=%d\n"
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,logical_end, physical_end, ext_physical_end, ext_cyl);
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#endif
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if (logical_end == physical_end ||
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(end_cyl == 1023 && ext_physical_end == logical_end)) {
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geom[0] = end_head + 1;
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geom[1] = end_sector;
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geom[2] = (unsigned long)capacity /
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((end_head + 1) * end_sector);
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ret = true;
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goto out_free_buf;
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}
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#ifdef DEBUG
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printk("scsicam_bios_param : logical (%u) != physical (%u)\n",
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logical_end, physical_end);
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#endif
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}
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out_free_buf:
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kfree(buf);
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return ret;
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}
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EXPORT_SYMBOL(scsi_partsize);
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/*
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* Function : static int setsize(unsigned long capacity,unsigned int *cyls,
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* unsigned int *hds, unsigned int *secs);
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*
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* Purpose : to determine a near-optimal int 0x13 mapping for a
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* SCSI disk in terms of lost space of size capacity, storing
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* the results in *cyls, *hds, and *secs.
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*
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* Returns : -1 on failure, 0 on success.
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*
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* Extracted from
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*
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* WORKING X3T9.2
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* DRAFT 792D
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* see http://www.t10.org/ftp/t10/drafts/cam/cam-r12b.pdf
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*
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* Revision 6
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* 10-MAR-94
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* Information technology -
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* SCSI-2 Common access method
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* transport and SCSI interface module
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*
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* ANNEX A :
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*
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* setsize() converts a read capacity value to int 13h
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* head-cylinder-sector requirements. It minimizes the value for
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* number of heads and maximizes the number of cylinders. This
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* will support rather large disks before the number of heads
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* will not fit in 4 bits (or 6 bits). This algorithm also
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* minimizes the number of sectors that will be unused at the end
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* of the disk while allowing for very large disks to be
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* accommodated. This algorithm does not use physical geometry.
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*/
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static int setsize(unsigned long capacity, unsigned int *cyls, unsigned int *hds,
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unsigned int *secs)
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{
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unsigned int rv = 0;
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unsigned long heads, sectors, cylinders, temp;
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cylinders = 1024L; /* Set number of cylinders to max */
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sectors = 62L; /* Maximize sectors per track */
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temp = cylinders * sectors; /* Compute divisor for heads */
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heads = capacity / temp; /* Compute value for number of heads */
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if (capacity % temp) { /* If no remainder, done! */
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heads++; /* Else, increment number of heads */
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temp = cylinders * heads; /* Compute divisor for sectors */
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sectors = capacity / temp; /* Compute value for sectors per
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track */
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if (capacity % temp) { /* If no remainder, done! */
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sectors++; /* Else, increment number of sectors */
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temp = heads * sectors; /* Compute divisor for cylinders */
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cylinders = capacity / temp; /* Compute number of cylinders */
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}
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}
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if (cylinders == 0)
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rv = (unsigned) -1; /* Give error if 0 cylinders */
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*cyls = (unsigned int) cylinders; /* Stuff return values */
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*secs = (unsigned int) sectors;
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*hds = (unsigned int) heads;
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return (rv);
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}
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/**
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* scsicam_bios_param - Determine geometry of a disk in cylinders/heads/sectors.
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* @bdev: which device
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* @capacity: size of the disk in sectors
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* @ip: return value: ip[0]=heads, ip[1]=sectors, ip[2]=cylinders
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*
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* Description : determine the BIOS mapping/geometry used for a drive in a
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* SCSI-CAM system, storing the results in ip as required
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* by the HDIO_GETGEO ioctl().
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*
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* Returns : -1 on failure, 0 on success.
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*/
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int scsicam_bios_param(struct block_device *bdev, sector_t capacity, int *ip)
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{
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u64 capacity64 = capacity; /* Suppress gcc warning */
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int ret = 0;
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/* try to infer mapping from partition table */
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if (scsi_partsize(bdev, capacity, ip))
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return 0;
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if (capacity64 < (1ULL << 32)) {
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/*
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* Pick some standard mapping with at most 1024 cylinders, and
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* at most 62 sectors per track - this works up to 7905 MB.
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*/
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ret = setsize((unsigned long)capacity, (unsigned int *)ip + 2,
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(unsigned int *)ip + 0, (unsigned int *)ip + 1);
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}
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/*
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* If something went wrong, then apparently we have to return a geometry
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* with more than 1024 cylinders.
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*/
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if (ret || ip[0] > 255 || ip[1] > 63) {
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if ((capacity >> 11) > 65534) {
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ip[0] = 255;
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ip[1] = 63;
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} else {
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ip[0] = 64;
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ip[1] = 32;
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}
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if (capacity > 65535*63*255)
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ip[2] = 65535;
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else
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ip[2] = (unsigned long)capacity / (ip[0] * ip[1]);
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}
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return 0;
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}
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EXPORT_SYMBOL(scsicam_bios_param);
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