[PATCH 2/2]: ufs: not usual amounts of fragments per block

Evgeniy Dushistov
2006-05-25T06:35:39Z

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>

---

diff -upr -X linux-2.6.17-rc4-mm3/Documentation/dontdiff linux-2.6.17-rc4-mm3/fs/ufs/balloc.c linux-2.6.17-rc4-mm3.mod/fs/ufs/balloc.c
--- linux-2.6.17-rc4-mm3/fs/ufs/balloc.c 2006-05-25 10:25:32.962540750 +0400
+++ linux-2.6.17-rc4-mm3.mod/fs/ufs/balloc.c 2006-05-25 10:26:57.807843250 +0400
@@ -726,18 +726,63 @@ gotit:
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;
+ unsigned rest, offset;
+ unsigned char *cp;

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

- uspi = UFS_SB(sb)->s_uspi;
+ 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));
+
usb1 = ubh_get_usb_first (uspi);
ucg = ubh_get_ucg(UCPI_UBH(ucpi));

@@ -747,53 +792,50 @@ static unsigned ufs_bitmap_search (struc
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;
}

diff -upr -X linux-2.6.17-rc4-mm3/Documentation/dontdiff linux-2.6.17-rc4-mm3/fs/ufs/util.h linux-2.6.17-rc4-mm3.mod/fs/ufs/util.h
--- linux-2.6.17-rc4-mm3/fs/ufs/util.h 2006-05-25 10:25:32.970541250 +0400
+++ linux-2.6.17-rc4-mm3.mod/fs/ufs/util.h 2006-05-25 10:26:57.839845250 +0400
@@ -513,29 +513,3 @@ static inline void ufs_fragacct (struct
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);
-}

--
/Evgeniy