ocfs2: avoid unaligned access to dqc_bitmap

The dqc_bitmap field of struct ocfs2_local_disk_chunk is 32-bit aligned,
but not 64-bit aligned.  The dqc_bitmap is accessed by ocfs2_set_bit(),
ocfs2_clear_bit(), ocfs2_test_bit(), or ocfs2_find_next_zero_bit().  These
are wrapper macros for ext2_*_bit() which need to take an unsigned long
aligned address (though some architectures are able to handle unaligned
address correctly)

So some 64bit architectures may not be able to access the dqc_bitmap
correctly.

This avoids such unaligned access by using another wrapper functions for
ext2_*_bit().  The code is taken from fs/ext4/mballoc.c which also need to
handle unaligned bitmap access.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index bcde467acca396a1916831849bc495faa5d413b5..d355e6e36b366bfe7dc8cc91cbabdad05976ba2c 100644 (file)
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -849,5 +849,52 @@ static inline void _ocfs2_clear_bit(unsigned int bit, unsigned long *bitmap)
 #define ocfs2_test_bit test_bit_le
 #define ocfs2_find_next_zero_bit find_next_zero_bit_le
 #define ocfs2_find_next_bit find_next_bit_le
+
+static inline void *correct_addr_and_bit_unaligned(int *bit, void *addr)
+{
+#if BITS_PER_LONG == 64
+       *bit += ((unsigned long) addr & 7UL) << 3;
+       addr = (void *) ((unsigned long) addr & ~7UL);
+#elif BITS_PER_LONG == 32
+       *bit += ((unsigned long) addr & 3UL) << 3;
+       addr = (void *) ((unsigned long) addr & ~3UL);
+#else
+#error "how many bits you are?!"
+#endif
+       return addr;
+}
+
+static inline void ocfs2_set_bit_unaligned(int bit, void *bitmap)
+{
+       bitmap = correct_addr_and_bit_unaligned(&bit, bitmap);
+       ocfs2_set_bit(bit, bitmap);
+}
+
+static inline void ocfs2_clear_bit_unaligned(int bit, void *bitmap)
+{
+       bitmap = correct_addr_and_bit_unaligned(&bit, bitmap);
+       ocfs2_clear_bit(bit, bitmap);
+}
+
+static inline int ocfs2_test_bit_unaligned(int bit, void *bitmap)
+{
+       bitmap = correct_addr_and_bit_unaligned(&bit, bitmap);
+       return ocfs2_test_bit(bit, bitmap);
+}
+
+static inline int ocfs2_find_next_zero_bit_unaligned(void *bitmap, int max,
+                                                       int start)
+{
+       int fix = 0, ret, tmpmax;
+       bitmap = correct_addr_and_bit_unaligned(&fix, bitmap);
+       tmpmax = max + fix;
+       start += fix;
+
+       ret = ocfs2_find_next_zero_bit(bitmap, tmpmax, start) - fix;
+       if (ret > max)
+               return max;
+       return ret;
+}
+
 #endif  /* OCFS2_H */
 

diff --git a/fs/ocfs2/quota_local.c b/fs/ocfs2/quota_local.c
index 942fd65bdad3fe2be63f42f4539a92343a2eb9f6..f100bf70a9066ed1b917b8ec0451c27231840f92 100644 (file)
--- a/fs/ocfs2/quota_local.c
+++ b/fs/ocfs2/quota_local.c
@@ -551,8 +551,8 @@ static int ocfs2_recover_local_quota_file(struct inode *lqinode,
                                goto out_commit;
                        }
                        lock_buffer(qbh);
-                       WARN_ON(!ocfs2_test_bit(bit, dchunk->dqc_bitmap));
-                       ocfs2_clear_bit(bit, dchunk->dqc_bitmap);
+                       WARN_ON(!ocfs2_test_bit_unaligned(bit, dchunk->dqc_bitmap));
+                       ocfs2_clear_bit_unaligned(bit, dchunk->dqc_bitmap);
                        le32_add_cpu(&dchunk->dqc_free, 1);
                        unlock_buffer(qbh);
                        ocfs2_journal_dirty(handle, qbh);
@@ -949,7 +949,7 @@ static struct ocfs2_quota_chunk *ocfs2_find_free_entry(struct super_block *sb,
                      * ol_quota_entries_per_block(sb);
        }
 
-       found = ocfs2_find_next_zero_bit(dchunk->dqc_bitmap, len, 0);
+       found = ocfs2_find_next_zero_bit_unaligned(dchunk->dqc_bitmap, len, 0);
        /* We failed? */
        if (found == len) {
                mlog(ML_ERROR, "Did not find empty entry in chunk %d with %u"
@@ -1213,7 +1213,7 @@ static void olq_alloc_dquot(struct buffer_head *bh, void *private)
        struct ocfs2_local_disk_chunk *dchunk;
 
        dchunk = (struct ocfs2_local_disk_chunk *)bh->b_data;
-       ocfs2_set_bit(*offset, dchunk->dqc_bitmap);
+       ocfs2_set_bit_unaligned(*offset, dchunk->dqc_bitmap);
        le32_add_cpu(&dchunk->dqc_free, -1);
 }
 
@@ -1294,7 +1294,7 @@ int ocfs2_local_release_dquot(handle_t *handle, struct dquot *dquot)
                        (od->dq_chunk->qc_headerbh->b_data);
        /* Mark structure as freed */
        lock_buffer(od->dq_chunk->qc_headerbh);
-       ocfs2_clear_bit(offset, dchunk->dqc_bitmap);
+       ocfs2_clear_bit_unaligned(offset, dchunk->dqc_bitmap);
        le32_add_cpu(&dchunk->dqc_free, 1);
        unlock_buffer(od->dq_chunk->qc_headerbh);
        ocfs2_journal_dirty(handle, od->dq_chunk->qc_headerbh);