Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 407 insertions, 0 deletions

diff --git a/fs/adfs/map.c b/fs/adfs/map.c
new file mode 100644
index 000000000..a81de80c4
--- /dev/null
+++ b/fs/adfs/map.c
@@ -0,0 +1,407 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  linux/fs/adfs/map.c
+ *
+ *  Copyright (C) 1997-2002 Russell King
+ */
+#include <linux/slab.h>
+#include <linux/statfs.h>
+#include <asm/unaligned.h>
+#include "adfs.h"
+
+/*
+ * The ADFS map is basically a set of sectors.  Each sector is called a
+ * zone which contains a bitstream made up of variable sized fragments.
+ * Each bit refers to a set of bytes in the filesystem, defined by
+ * log2bpmb.  This may be larger or smaller than the sector size, but
+ * the overall size it describes will always be a round number of
+ * sectors.  A fragment id is always idlen bits long.
+ *
+ *  < idlen > <       n        > <1>
+ * +---------+-------//---------+---+
+ * | frag id |  0000....000000  | 1 |
+ * +---------+-------//---------+---+
+ *
+ * The physical disk space used by a fragment is taken from the start of
+ * the fragment id up to and including the '1' bit - ie, idlen + n + 1
+ * bits.
+ *
+ * A fragment id can be repeated multiple times in the whole map for
+ * large or fragmented files.  The first map zone a fragment starts in
+ * is given by fragment id / ids_per_zone - this allows objects to start
+ * from any zone on the disk.
+ *
+ * Free space is described by a linked list of fragments.  Each free
+ * fragment describes free space in the same way as the other fragments,
+ * however, the frag id specifies an offset (in map bits) from the end
+ * of this fragment to the start of the next free fragment.
+ *
+ * Objects stored on the disk are allocated object ids (we use these as
+ * our inode numbers.)  Object ids contain a fragment id and an optional
+ * offset.  This allows a directory fragment to contain small files
+ * associated with that directory.
+ */
+
+/*
+ * For the future...
+ */
+static DEFINE_RWLOCK(adfs_map_lock);
+
+/*
+ * This is fun.  We need to load up to 19 bits from the map at an
+ * arbitrary bit alignment.  (We're limited to 19 bits by F+ version 2).
+ */
+#define GET_FRAG_ID(_map,_start,_idmask)				\
+	({								\
+		unsigned char *_m = _map + (_start >> 3);		\
+		u32 _frag = get_unaligned_le32(_m);			\
+		_frag >>= (_start & 7);					\
+		_frag & _idmask;					\
+	})
+
+/*
+ * return the map bit offset of the fragment frag_id in the zone dm.
+ * Note that the loop is optimised for best asm code - look at the
+ * output of:
+ *  gcc -D__KERNEL__ -O2 -I../../include -o - -S map.c
+ */
+static int lookup_zone(const struct adfs_discmap *dm, const unsigned int idlen,
+		       const u32 frag_id, unsigned int *offset)
+{
+	const unsigned int endbit = dm->dm_endbit;
+	const u32 idmask = (1 << idlen) - 1;
+	unsigned char *map = dm->dm_bh->b_data;
+	unsigned int start = dm->dm_startbit;
+	unsigned int freelink, fragend;
+	u32 frag;
+
+	frag = GET_FRAG_ID(map, 8, idmask & 0x7fff);
+	freelink = frag ? 8 + frag : 0;
+
+	do {
+		frag = GET_FRAG_ID(map, start, idmask);
+
+		fragend = find_next_bit_le(map, endbit, start + idlen);
+		if (fragend >= endbit)
+			goto error;
+
+		if (start == freelink) {
+			freelink += frag & 0x7fff;
+		} else if (frag == frag_id) {
+			unsigned int length = fragend + 1 - start;
+
+			if (*offset < length)
+				return start + *offset;
+			*offset -= length;
+		}
+
+		start = fragend + 1;
+	} while (start < endbit);
+	return -1;
+
+error:
+	printk(KERN_ERR "adfs: oversized fragment 0x%x at 0x%x-0x%x\n",
+		frag, start, fragend);
+	return -1;
+}
+
+/*
+ * Scan the free space map, for this zone, calculating the total
+ * number of map bits in each free space fragment.
+ *
+ * Note: idmask is limited to 15 bits [3.2]
+ */
+static unsigned int
+scan_free_map(struct adfs_sb_info *asb, struct adfs_discmap *dm)
+{
+	const unsigned int endbit = dm->dm_endbit;
+	const unsigned int idlen  = asb->s_idlen;
+	const unsigned int frag_idlen = idlen <= 15 ? idlen : 15;
+	const u32 idmask = (1 << frag_idlen) - 1;
+	unsigned char *map = dm->dm_bh->b_data;
+	unsigned int start = 8, fragend;
+	u32 frag;
+	unsigned long total = 0;
+
+	/*
+	 * get fragment id
+	 */
+	frag = GET_FRAG_ID(map, start, idmask);
+
+	/*
+	 * If the freelink is null, then no free fragments
+	 * exist in this zone.
+	 */
+	if (frag == 0)
+		return 0;
+
+	do {
+		start += frag;
+
+		frag = GET_FRAG_ID(map, start, idmask);
+
+		fragend = find_next_bit_le(map, endbit, start + idlen);
+		if (fragend >= endbit)
+			goto error;
+
+		total += fragend + 1 - start;
+	} while (frag >= idlen + 1);
+
+	if (frag != 0)
+		printk(KERN_ERR "adfs: undersized free fragment\n");
+
+	return total;
+error:
+	printk(KERN_ERR "adfs: oversized free fragment\n");
+	return 0;
+}
+
+static int scan_map(struct adfs_sb_info *asb, unsigned int zone,
+		    const u32 frag_id, unsigned int mapoff)
+{
+	const unsigned int idlen = asb->s_idlen;
+	struct adfs_discmap *dm, *dm_end;
+	int result;
+
+	dm	= asb->s_map + zone;
+	zone	= asb->s_map_size;
+	dm_end	= asb->s_map + zone;
+
+	do {
+		result = lookup_zone(dm, idlen, frag_id, &mapoff);
+
+		if (result != -1)
+			goto found;
+
+		dm ++;
+		if (dm == dm_end)
+			dm = asb->s_map;
+	} while (--zone > 0);
+
+	return -1;
+found:
+	result -= dm->dm_startbit;
+	result += dm->dm_startblk;
+
+	return result;
+}
+
+/*
+ * calculate the amount of free blocks in the map.
+ *
+ *              n=1
+ *  total_free = E(free_in_zone_n)
+ *              nzones
+ */
+void adfs_map_statfs(struct super_block *sb, struct kstatfs *buf)
+{
+	struct adfs_sb_info *asb = ADFS_SB(sb);
+	struct adfs_discrecord *dr = adfs_map_discrecord(asb->s_map);
+	struct adfs_discmap *dm;
+	unsigned int total = 0;
+	unsigned int zone;
+
+	dm   = asb->s_map;
+	zone = asb->s_map_size;
+
+	do {
+		total += scan_free_map(asb, dm++);
+	} while (--zone > 0);
+
+	buf->f_blocks  = adfs_disc_size(dr) >> sb->s_blocksize_bits;
+	buf->f_files   = asb->s_ids_per_zone * asb->s_map_size;
+	buf->f_bavail  =
+	buf->f_bfree   = signed_asl(total, asb->s_map2blk);
+}
+
+int adfs_map_lookup(struct super_block *sb, u32 frag_id, unsigned int offset)
+{
+	struct adfs_sb_info *asb = ADFS_SB(sb);
+	unsigned int zone, mapoff;
+	int result;
+
+	/*
+	 * map & root fragment is special - it starts in the center of the
+	 * disk.  The other fragments start at zone (frag / ids_per_zone)
+	 */
+	if (frag_id == ADFS_ROOT_FRAG)
+		zone = asb->s_map_size >> 1;
+	else
+		zone = frag_id / asb->s_ids_per_zone;
+
+	if (zone >= asb->s_map_size)
+		goto bad_fragment;
+
+	/* Convert sector offset to map offset */
+	mapoff = signed_asl(offset, -asb->s_map2blk);
+
+	read_lock(&adfs_map_lock);
+	result = scan_map(asb, zone, frag_id, mapoff);
+	read_unlock(&adfs_map_lock);
+
+	if (result > 0) {
+		unsigned int secoff;
+
+		/* Calculate sector offset into map block */
+		secoff = offset - signed_asl(mapoff, asb->s_map2blk);
+		return secoff + signed_asl(result, asb->s_map2blk);
+	}
+
+	adfs_error(sb, "fragment 0x%04x at offset %d not found in map",
+		   frag_id, offset);
+	return 0;
+
+bad_fragment:
+	adfs_error(sb, "invalid fragment 0x%04x (zone = %d, max = %d)",
+		   frag_id, zone, asb->s_map_size);
+	return 0;
+}
+
+static unsigned char adfs_calczonecheck(struct super_block *sb, unsigned char *map)
+{
+	unsigned int v0, v1, v2, v3;
+	int i;
+
+	v0 = v1 = v2 = v3 = 0;
+	for (i = sb->s_blocksize - 4; i; i -= 4) {
+		v0 += map[i]     + (v3 >> 8);
+		v3 &= 0xff;
+		v1 += map[i + 1] + (v0 >> 8);
+		v0 &= 0xff;
+		v2 += map[i + 2] + (v1 >> 8);
+		v1 &= 0xff;
+		v3 += map[i + 3] + (v2 >> 8);
+		v2 &= 0xff;
+	}
+	v0 +=           v3 >> 8;
+	v1 += map[1] + (v0 >> 8);
+	v2 += map[2] + (v1 >> 8);
+	v3 += map[3] + (v2 >> 8);
+
+	return v0 ^ v1 ^ v2 ^ v3;
+}
+
+static int adfs_checkmap(struct super_block *sb, struct adfs_discmap *dm)
+{
+	unsigned char crosscheck = 0, zonecheck = 1;
+	int i;
+
+	for (i = 0; i < ADFS_SB(sb)->s_map_size; i++) {
+		unsigned char *map;
+
+		map = dm[i].dm_bh->b_data;
+
+		if (adfs_calczonecheck(sb, map) != map[0]) {
+			adfs_error(sb, "zone %d fails zonecheck", i);
+			zonecheck = 0;
+		}
+		crosscheck ^= map[3];
+	}
+	if (crosscheck != 0xff)
+		adfs_error(sb, "crosscheck != 0xff");
+	return crosscheck == 0xff && zonecheck;
+}
+
+/*
+ * Layout the map - the first zone contains a copy of the disc record,
+ * and the last zone must be limited to the size of the filesystem.
+ */
+static void adfs_map_layout(struct adfs_discmap *dm, unsigned int nzones,
+			    struct adfs_discrecord *dr)
+{
+	unsigned int zone, zone_size;
+	u64 size;
+
+	zone_size = (8 << dr->log2secsize) - le16_to_cpu(dr->zone_spare);
+
+	dm[0].dm_bh       = NULL;
+	dm[0].dm_startblk = 0;
+	dm[0].dm_startbit = 32 + ADFS_DR_SIZE_BITS;
+	dm[0].dm_endbit   = 32 + zone_size;
+
+	for (zone = 1; zone < nzones; zone++) {
+		dm[zone].dm_bh       = NULL;
+		dm[zone].dm_startblk = zone * zone_size - ADFS_DR_SIZE_BITS;
+		dm[zone].dm_startbit = 32;
+		dm[zone].dm_endbit   = 32 + zone_size;
+	}
+
+	size = adfs_disc_size(dr) >> dr->log2bpmb;
+	size -= (nzones - 1) * zone_size - ADFS_DR_SIZE_BITS;
+	dm[nzones - 1].dm_endbit = 32 + size;
+}
+
+static int adfs_map_read(struct adfs_discmap *dm, struct super_block *sb,
+			 unsigned int map_addr, unsigned int nzones)
+{
+	unsigned int zone;
+
+	for (zone = 0; zone < nzones; zone++) {
+		dm[zone].dm_bh = sb_bread(sb, map_addr + zone);
+		if (!dm[zone].dm_bh)
+			return -EIO;
+	}
+
+	return 0;
+}
+
+static void adfs_map_relse(struct adfs_discmap *dm, unsigned int nzones)
+{
+	unsigned int zone;
+
+	for (zone = 0; zone < nzones; zone++)
+		brelse(dm[zone].dm_bh);
+}
+
+struct adfs_discmap *adfs_read_map(struct super_block *sb, struct adfs_discrecord *dr)
+{
+	struct adfs_sb_info *asb = ADFS_SB(sb);
+	struct adfs_discmap *dm;
+	unsigned int map_addr, zone_size, nzones;
+	int ret;
+
+	nzones    = dr->nzones | dr->nzones_high << 8;
+	zone_size = (8 << dr->log2secsize) - le16_to_cpu(dr->zone_spare);
+
+	asb->s_idlen = dr->idlen;
+	asb->s_map_size = nzones;
+	asb->s_map2blk = dr->log2bpmb - dr->log2secsize;
+	asb->s_log2sharesize = dr->log2sharesize;
+	asb->s_ids_per_zone = zone_size / (asb->s_idlen + 1);
+
+	map_addr = (nzones >> 1) * zone_size -
+		     ((nzones > 1) ? ADFS_DR_SIZE_BITS : 0);
+	map_addr = signed_asl(map_addr, asb->s_map2blk);
+
+	dm = kmalloc_array(nzones, sizeof(*dm), GFP_KERNEL);
+	if (dm == NULL) {
+		adfs_error(sb, "not enough memory");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	adfs_map_layout(dm, nzones, dr);
+
+	ret = adfs_map_read(dm, sb, map_addr, nzones);
+	if (ret) {
+		adfs_error(sb, "unable to read map");
+		goto error_free;
+	}
+
+	if (adfs_checkmap(sb, dm))
+		return dm;
+
+	adfs_error(sb, "map corrupted");
+
+error_free:
+	adfs_map_relse(dm, nzones);
+	kfree(dm);
+	return ERR_PTR(-EIO);
+}
+
+void adfs_free_map(struct super_block *sb)
+{
+	struct adfs_sb_info *asb = ADFS_SB(sb);
+
+	adfs_map_relse(asb->s_map, asb->s_map_size);
+	kfree(asb->s_map);
+}