[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: Evgeniy Dushistov <dushistov@mail.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/fs/ufs/balloc.c b/fs/ufs/balloc.c
index 68de1312e4b6cb630aa73732b85f580ae5691a47..343eaf4542f892774e23d340cb55f10e9d06b4d2 100644 (file)
--- a/fs/ufs/balloc.c
+++ b/fs/ufs/balloc.c
@@ -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;
-       
-       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));
 
@@ -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;
 }
 

diff --git a/fs/ufs/util.h b/fs/ufs/util.h
index 6a0b48cf9cef8dab07ccba43bfbe35d19c4b87ec..e95d1c46461f880a7abdde74a67735af1b3e07df 100644 (file)
--- a/fs/ufs/util.h
+++ b/fs/ufs/util.h
@@ -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);
-}