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Commit 3e41f597 authored by Evgeniy Dushistov's avatar Evgeniy Dushistov Committed by Linus Torvalds
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[PATCH] ufs: not usual amounts of fragments per block 



The writing to UFS file system with block/fragment!=8 may cause bogus
behaviour.  The problem in "ufs_bitmap_search" function, which doesn't work
correctly in "block/fragment!=8" case.  The idea is stolen from BSD code.

Signed-off-by: default avatarEvgeniy Dushistov <dushistov@mail.ru>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 9695ef16

fs/ufs/balloc.c

+87 −45
Original line number Diff line number Diff line
@@ -726,18 +726,63 @@ static unsigned ufs_alloccg_block (struct inode * inode, 
	return result;

}



static unsigned ubh_scanc(struct ufs_sb_private_info *uspi,

			  struct ufs_buffer_head *ubh,

			  unsigned begin, unsigned size,

			  unsigned char *table, unsigned char mask)

{

	unsigned rest, offset;

	unsigned char *cp;

	



	offset = begin & ~uspi->s_fmask;

	begin >>= uspi->s_fshift;

	for (;;) {

		if ((offset + size) < uspi->s_fsize)

			rest = size;

		else

			rest = uspi->s_fsize - offset;

		size -= rest;

		cp = ubh->bh[begin]->b_data + offset;

		while ((table[*cp++] & mask) == 0 && --rest)

			;

		if (rest || !size)

			break;

		begin++;

		offset = 0;

	}

	return (size + rest);

}



/*

 * Find a block of the specified size in the specified cylinder group.

 * @sp: pointer to super block

 * @ucpi: pointer to cylinder group info

 * @goal: near which block we want find new one

 * @count: specified size

 */

static unsigned ufs_bitmap_search(struct super_block *sb,

	struct ufs_cg_private_info * ucpi, unsigned goal, unsigned count)

				  struct ufs_cg_private_info *ucpi,

				  unsigned goal, unsigned count)

{

	struct ufs_sb_private_info * uspi;

	/*

	 * Bit patterns for identifying fragments in the block map

	 * used as ((map & mask_arr) == want_arr)

	 */

	static const int mask_arr[9] = {

		0x3, 0x7, 0xf, 0x1f, 0x3f, 0x7f, 0xff, 0x1ff, 0x3ff

	};

	static const int want_arr[9] = {

		0x0, 0x2, 0x6, 0xe, 0x1e, 0x3e, 0x7e, 0xfe, 0x1fe

	};

	struct ufs_sb_private_info *uspi = UFS_SB(sb)->s_uspi;

	struct ufs_super_block_first *usb1;

	struct ufs_cylinder_group *ucg;

	unsigned start, length, location, result;

	unsigned possition, fragsize, blockmap, mask;

	unsigned start, length, loc, result;

	unsigned pos, want, blockmap, mask, end;



	UFSD(("ENTER, cg %u, goal %u, count %u\n", ucpi->c_cgx, goal, count))

	UFSD(("ENTER, cg %u, goal %u, count %u\n", ucpi->c_cgx, goal, count));



	uspi = UFS_SB(sb)->s_uspi;

	usb1 = ubh_get_usb_first (uspi);

	ucg = ubh_get_ucg(UCPI_UBH(ucpi));
@@ -747,53 +792,50 @@ static unsigned ufs_bitmap_search (struct super_block * sb, 
		start = ucpi->c_frotor >> 3;

		

	length = ((uspi->s_fpg + 7) >> 3) - start;

	location = ubh_scanc(UCPI_UBH(ucpi), ucpi->c_freeoff + start, length,

	loc = ubh_scanc(uspi, UCPI_UBH(ucpi), ucpi->c_freeoff + start, length,

		(uspi->s_fpb == 8) ? ufs_fragtable_8fpb : ufs_fragtable_other,

		1 << (count - 1 + (uspi->s_fpb & 7))); 

	if (location == 0) {

	if (loc == 0) {

		length = start + 1;

		location = ubh_scanc(UCPI_UBH(ucpi), ucpi->c_freeoff, length,

			(uspi->s_fpb == 8) ? ufs_fragtable_8fpb : ufs_fragtable_other,

		loc = ubh_scanc(uspi, UCPI_UBH(ucpi), ucpi->c_freeoff, length,

				(uspi->s_fpb == 8) ? ufs_fragtable_8fpb :

				ufs_fragtable_other,

				1 << (count - 1 + (uspi->s_fpb & 7)));

		if (location == 0) {

		if (loc == 0) {

			ufs_error(sb, "ufs_bitmap_search",

			"bitmap corrupted on cg %u, start %u, length %u, count %u, freeoff %u\n",

			ucpi->c_cgx, start, length, count, ucpi->c_freeoff);

				  "bitmap corrupted on cg %u, start %u,"

				  " length %u, count %u, freeoff %u\n",

				  ucpi->c_cgx, start, length, count,

				  ucpi->c_freeoff);

			return (unsigned)-1;

		}

		start = 0;

	}

	result = (start + length - location) << 3;

	result = (start + length - loc) << 3;

	ucpi->c_frotor = result;



	/*

	 * found the byte in the map

	 */



	for (end = result + 8; result < end; result += uspi->s_fpb) {

		blockmap = ubh_blkmap(UCPI_UBH(ucpi), ucpi->c_freeoff, result);

	fragsize = 0;

	for (possition = 0, mask = 1; possition < 8; possition++, mask <<= 1) {

		if (blockmap & mask) {

			if (!(possition & uspi->s_fpbmask))

				fragsize = 1;

			else 

				fragsize++;

		}

		else {

			if (fragsize == count) {

				result += possition - count;

				UFSD(("EXIT, result %u\n", result))

				return result;

		blockmap <<= 1;

		mask = mask_arr[count];

		want = want_arr[count];

		for (pos = 0; pos <= uspi->s_fpb - count; pos++) {

			if ((blockmap & mask) == want) {

				UFSD(("EXIT, result %u\n", result));

				return result + pos;

 			}

			fragsize = 0;

			mask <<= 1;

			want <<= 1;

 		}

 	}

	if (fragsize == count) {

		result += possition - count;

		UFSD(("EXIT, result %u\n", result))

		return result;

	}

	ufs_error (sb, "ufs_bitmap_search", "block not in map on cg %u\n", ucpi->c_cgx);

	UFSD(("EXIT (FAILED)\n"))



	ufs_error(sb, "ufs_bitmap_search", "block not in map on cg %u\n",

		  ucpi->c_cgx);

	UFSD(("EXIT (FAILED)\n"));

	return (unsigned)-1;

}

fs/ufs/util.h

+0 −26
Original line number Diff line number Diff line
@@ -513,29 +513,3 @@ static inline void ufs_fragacct (struct super_block * sb, unsigned blockmap, 
	if (fragsize > 0 && fragsize < uspi->s_fpb)

		fs32_add(sb, &fraglist[fragsize], cnt);

}
 


#define ubh_scanc(ubh,begin,size,table,mask) _ubh_scanc_(uspi,ubh,begin,size,table,mask)

static inline unsigned _ubh_scanc_(struct ufs_sb_private_info * uspi, struct ufs_buffer_head * ubh, 

	unsigned begin, unsigned size, unsigned char * table, unsigned char mask)

{

	unsigned rest, offset;

	unsigned char * cp;

	



	offset = begin & ~uspi->s_fmask;

	begin >>= uspi->s_fshift;

	for (;;) {

		if ((offset + size) < uspi->s_fsize)

			rest = size;

		else

			rest = uspi->s_fsize - offset;

		size -= rest;

		cp = ubh->bh[begin]->b_data + offset;

		while ((table[*cp++] & mask) == 0 && --rest);

		if (rest || !size)

			break;

		begin++;

		offset = 0;

	}

	return (size + rest);

}