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-rw-r--r--fs/buffer.c6
-rw-r--r--fs/ocfs2/journal.c2
-rw-r--r--fs/reiserfs/prints.c2
-rw-r--r--include/linux/buffer_head.h19
4 files changed, 17 insertions, 12 deletions
diff --git a/fs/buffer.c b/fs/buffer.c
index f25f5809642..e7a1461f438 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -426,8 +426,10 @@ __find_get_block_slow(struct block_device *bdev, sector_t block)
if (all_mapped) {
printk("__find_get_block_slow() failed. "
"block=%llu, b_blocknr=%llu\n",
- (unsigned long long)block, (unsigned long long)bh->b_blocknr);
- printk("b_state=0x%08lx, b_size=%u\n", bh->b_state, bh->b_size);
+ (unsigned long long)block,
+ (unsigned long long)bh->b_blocknr);
+ printk("b_state=0x%08lx, b_size=%zu\n",
+ bh->b_state, bh->b_size);
printk("device blocksize: %d\n", 1 << bd_inode->i_blkbits);
}
out_unlock:
diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index 90641929a43..6a610ae5358 100644
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -377,7 +377,7 @@ int ocfs2_journal_access(struct ocfs2_journal_handle *handle,
BUG_ON(!bh);
BUG_ON(!(handle->flags & OCFS2_HANDLE_STARTED));
- mlog_entry("bh->b_blocknr=%llu, type=%d (\"%s\"), bh->b_size = %hu\n",
+ mlog_entry("bh->b_blocknr=%llu, type=%d (\"%s\"), bh->b_size = %zu\n",
(unsigned long long)bh->b_blocknr, type,
(type == OCFS2_JOURNAL_ACCESS_CREATE) ?
"OCFS2_JOURNAL_ACCESS_CREATE" :
diff --git a/fs/reiserfs/prints.c b/fs/reiserfs/prints.c
index 78b40621b88..27bd3a1df2a 100644
--- a/fs/reiserfs/prints.c
+++ b/fs/reiserfs/prints.c
@@ -143,7 +143,7 @@ static void sprintf_buffer_head(char *buf, struct buffer_head *bh)
char b[BDEVNAME_SIZE];
sprintf(buf,
- "dev %s, size %d, blocknr %llu, count %d, state 0x%lx, page %p, (%s, %s, %s)",
+ "dev %s, size %zd, blocknr %llu, count %d, state 0x%lx, page %p, (%s, %s, %s)",
bdevname(bh->b_bdev, b), bh->b_size,
(unsigned long long)bh->b_blocknr, atomic_read(&(bh->b_count)),
bh->b_state, bh->b_page,
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index da917ed096a..464f068f8b1 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -46,25 +46,28 @@ struct address_space;
typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);
/*
- * Keep related fields in common cachelines. The most commonly accessed
- * field (b_state) goes at the start so the compiler does not generate
- * indexed addressing for it.
+ * Historically, a buffer_head was used to map a single block
+ * within a page, and of course as the unit of I/O through the
+ * filesystem and block layers. Nowadays the basic I/O unit
+ * is the bio, and buffer_heads are used for extracting block
+ * mappings (via a get_block_t call), for tracking state within
+ * a page (via a page_mapping) and for wrapping bio submission
+ * for backward compatibility reasons (e.g. submit_bh).
*/
struct buffer_head {
- /* First cache line: */
unsigned long b_state; /* buffer state bitmap (see above) */
struct buffer_head *b_this_page;/* circular list of page's buffers */
struct page *b_page; /* the page this bh is mapped to */
- atomic_t b_count; /* users using this block */
- u32 b_size; /* block size */
- sector_t b_blocknr; /* block number */
- char *b_data; /* pointer to data block */
+ sector_t b_blocknr; /* start block number */
+ size_t b_size; /* size of mapping */
+ char *b_data; /* pointer to data within the page */
struct block_device *b_bdev;
bh_end_io_t *b_end_io; /* I/O completion */
void *b_private; /* reserved for b_end_io */
struct list_head b_assoc_buffers; /* associated with another mapping */
+ atomic_t b_count; /* users using this buffer_head */
};
/*