Convert ext2_count_free() to use memweight() instead of table lookup
based counting clear bits implementation. This change only affects
the code segments enabled by EXT2FS_DEBUG.
Note that this memweight() call can't be replaced with a single
bitmap_weight() call, although the pointer to the memory area is
aligned to long-word boundary. Because the size of the memory area
may not be a multiple of BITS_PER_LONG, then it returns wrong value on
big-endian architecture.
This also includes the following changes.
- Remove unnecessary map == NULL check in ext2_count_free() which
always takes non-null pointer as the memory area.
- Fix printk format warning that only reveals with EXT2FS_DEBUG.
Signed-off-by: Akinobu Mita <akinobu.mita@xxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: linux-ext4@xxxxxxxxxxxxxxx
---
v3: rewrite to keep ext2_count_free() as a wrapper for memweight()
fs/ext2/balloc.c | 14 ++------------
fs/ext2/ialloc.c | 1 +
2 files changed, 3 insertions(+), 12 deletions(-)
diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c
index 1c36139..376aa77 100644
--- a/fs/ext2/balloc.c
+++ b/fs/ext2/balloc.c
@@ -1444,19 +1444,9 @@ ext2_fsblk_t ext2_new_block(struct inode *inode, unsigned long goal, int *errp)
#ifdef EXT2FS_DEBUG
-static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
-
-unsigned long ext2_count_free (struct buffer_head * map, unsigned int numchars)
+unsigned long ext2_count_free(struct buffer_head *map, unsigned int numchars)
{
- unsigned int i;
- unsigned long sum = 0;
-
- if (!map)
- return (0);
- for (i = 0; i < numchars; i++)
- sum += nibblemap[map->b_data[i] & 0xf] +
- nibblemap[(map->b_data[i] >> 4) & 0xf];
- return (sum);
+ return numchars * BITS_PER_BYTE - memweight(map->b_data, numchars);
}
#endif /* EXT2FS_DEBUG */
diff --git a/fs/ext2/ialloc.c b/fs/ext2/ialloc.c
index c13eb7b..8f370e01 100644
--- a/fs/ext2/ialloc.c
+++ b/fs/ext2/ialloc.c
@@ -644,6 +644,7 @@ unsigned long ext2_count_free_inodes (struct super_block * sb)
}
brelse(bitmap_bh);
printk("ext2_count_free_inodes: stored = %lu, computed = %lu, %lu\n",
+ (unsigned long)
percpu_counter_read(&EXT2_SB(sb)->s_freeinodes_counter),
desc_count, bitmap_count);
return desc_count;
--
1.7.7.6
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