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fs/adfs: map: incorporate map offsets into layout

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lookup_zone() and scan_free_map() cope in different ways with the
location of the map data within a zone:

1. lookup_zone() adds a four byte offset to the map data pointer to
   skip over the check and free link bytes.

2. scan_free_map() needs to use the free link pointer, which is an
   offset from itself, so we end up adding a 32-bit offset to the
   end pointer (aka mapsize) which is really confusing.

Rename mapsize to endbit as this is really what it is, and incorporate
the 32-bit offset into the map layout.  This means that both dm_startbit
and dm_endbit are now bit offsets from the start of the buffer, rather
than four bytes in to the buffer.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Russell King 2019-12-09 11:08:49 +00:00 committed by Al Viro
parent 7b19526762
commit 197ba3c519
1 changed files with 11 additions and 11 deletions
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22
fs/adfs/map.c
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@ -68,9 +68,9 @@ static DEFINE_RWLOCK(adfs_map_lock);
static int lookup_zone(const struct adfs_discmap *dm, const unsigned int idlen,
const u32 frag_id, unsigned int *offset)
{
const unsigned int mapsize = dm->dm_endbit;
const unsigned int endbit = dm->dm_endbit;
const u32 idmask = (1 << idlen) - 1;
unsigned char *map = dm->dm_bh->b_data + 4;
unsigned char *map = dm->dm_bh->b_data;
unsigned int start = dm->dm_startbit;
unsigned int mapptr;
u32 frag;
@ -87,7 +87,7 @@ static int lookup_zone(const struct adfs_discmap *dm, const unsigned int idlen,
u32 v = le32_to_cpu(_map[mapptr >> 5]) >> (mapptr & 31);
while (v == 0) {
mapptr = (mapptr & ~31) + 32;
if (mapptr >= mapsize)
if (mapptr >= endbit)
goto error;
v = le32_to_cpu(_map[mapptr >> 5]);
}
@ -99,7 +99,7 @@ static int lookup_zone(const struct adfs_discmap *dm, const unsigned int idlen,
goto found;
again:
start = mapptr;
} while (mapptr < mapsize);
} while (mapptr < endbit);
return -1;
error:
@ -127,7 +127,7 @@ found:
static unsigned int
scan_free_map(struct adfs_sb_info *asb, struct adfs_discmap *dm)
{
const unsigned int mapsize = dm->dm_endbit + 32;
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;
@ -165,7 +165,7 @@ scan_free_map(struct adfs_sb_info *asb, struct adfs_discmap *dm)
u32 v = le32_to_cpu(_map[mapptr >> 5]) >> (mapptr & 31);
while (v == 0) {
mapptr = (mapptr & ~31) + 32;
if (mapptr >= mapsize)
if (mapptr >= endbit)
goto error;
v = le32_to_cpu(_map[mapptr >> 5]);
}
@ -345,19 +345,19 @@ static void adfs_map_layout(struct adfs_discmap *dm, unsigned int nzones,
dm[0].dm_bh = NULL;
dm[0].dm_startblk = 0;
dm[0].dm_startbit = ADFS_DR_SIZE_BITS;
dm[0].dm_endbit = zone_size;
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 = 0;
dm[zone].dm_endbit = zone_size;
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 = size;
dm[nzones - 1].dm_endbit = 32 + size;
}
static int adfs_map_read(struct adfs_discmap *dm, struct super_block *sb,