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[PATCH] ufs: not usual amounts of fragments per block
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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: Evgeniy Dushistov <dushistov@mail.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Evgeniy Dushistov authored and Linus Torvalds committed Jun 25, 2006
1 parent 9695ef1 commit 3e41f59
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Showing 2 changed files with 87 additions and 71 deletions.
132 changes: 87 additions & 45 deletions fs/ufs/balloc.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -726,18 +726,63 @@ static unsigned ufs_alloccg_block (struct inode * inode,
return result;
}

static unsigned ufs_bitmap_search (struct super_block * sb,
struct ufs_cg_private_info * ucpi, unsigned goal, unsigned count)
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)
{
struct ufs_sb_private_info * uspi;
struct ufs_super_block_first * usb1;
struct ufs_cylinder_group * ucg;
unsigned start, length, location, result;
unsigned possition, fragsize, blockmap, mask;

UFSD(("ENTER, cg %u, goal %u, count %u\n", ucpi->c_cgx, goal, count))
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)
{
/*
* 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, loc, result;
unsigned pos, want, blockmap, mask, end;

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));

Expand All @@ -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,
1 << (count - 1 + (uspi->s_fpb & 7)));
if (location == 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);
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 (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);
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
*/
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;
}
fragsize = 0;
}
}
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"))

for (end = result + 8; result < end; result += uspi->s_fpb) {
blockmap = ubh_blkmap(UCPI_UBH(ucpi), ucpi->c_freeoff, 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;
}
mask <<= 1;
want <<= 1;
}
}

ufs_error(sb, "ufs_bitmap_search", "block not in map on cg %u\n",
ucpi->c_cgx);
UFSD(("EXIT (FAILED)\n"));
return (unsigned)-1;
}

Expand Down
26 changes: 0 additions & 26 deletions fs/ufs/util.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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);
}

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