Increase the size of the buffer_head b_size field (only) for 64 bit platforms. Update some old and moldy comments in and around the structure as well. The b_size increase allows us to perform larger mappings and allocations for large I/O requests from userspace, which tie in with other changes allowing the get_block_t() interface to map multiple blocks at once.
Unified · Split
| @@ -426,8 +426,10 @@ __find_get_block_slow(struct block_device *bdev, sector_t block) · 425 unmodified lines | ||
| 426 | 426 | if (all_mapped) { |
| 427 | 427 | printk("__find_get_block_slow() failed. " |
| 428 | 428 | "block=%llu, b_blocknr=%llu\n", |
| 429 | − (unsigned long long)block, (unsigned long long)bh->b_blocknr); | |
| 430 | − printk("b_state=0x%08lx, b_size=%u\n", bh->b_state, bh->b_size); | |
| 429 | + (unsigned long long)block, | |
| 430 | + (unsigned long long)bh->b_blocknr); | |
| 431 | + printk("b_state=0x%08lx, b_size=%zu\n", | |
| 432 | + bh->b_state, bh->b_size); | |
| 431 | 433 | printk("device blocksize: %d\n", 1 << bd_inode->i_blkbits); |
| 432 | 434 | } |
| 433 | 435 | out_unlock: |
| @@ -377,7 +377,7 @@ int ocfs2_journal_access(struct ocfs2_journal_handle *handle, · 376 unmodified lines | ||
| 377 | 377 | BUG_ON(!bh); |
| 378 | 378 | BUG_ON(!(handle->flags & OCFS2_HANDLE_STARTED)); |
| 379 | 379 | |
| 380 | − mlog_entry("bh->b_blocknr=%llu, type=%d (\"%s\"), bh->b_size = %hu\n", | |
| 380 | + mlog_entry("bh->b_blocknr=%llu, type=%d (\"%s\"), bh->b_size = %zu\n", | |
| 381 | 381 | (unsigned long long)bh->b_blocknr, type, |
| 382 | 382 | (type == OCFS2_JOURNAL_ACCESS_CREATE) ? |
| 383 | 383 | "OCFS2_JOURNAL_ACCESS_CREATE" : |
| @@ -143,7 +143,7 @@ static void sprintf_buffer_head(char *buf, struct buffer_head *bh) · 142 unmodified lines | ||
| 143 | 143 | char b[BDEVNAME_SIZE]; |
| 144 | 144 | |
| 145 | 145 | sprintf(buf, |
| 146 | − "dev %s, size %d, blocknr %llu, count %d, state 0x%lx, page %p, (%s, %s, %s)", | |
| 146 | + "dev %s, size %zd, blocknr %llu, count %d, state 0x%lx, page %p, (%s, %s, %s)", | |
| 147 | 147 | bdevname(bh->b_bdev, b), bh->b_size, |
| 148 | 148 | (unsigned long long)bh->b_blocknr, atomic_read(&(bh->b_count)), |
| 149 | 149 | bh->b_state, bh->b_page, |
| @@ -46,25 +46,28 @@ struct address_space; · 45 unmodified lines | ||
| 46 | 46 | typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate); |
| 47 | 47 | |
| 48 | 48 | /* |
| 49 | − * Keep related fields in common cachelines. The most commonly accessed | |
| 50 | − * field (b_state) goes at the start so the compiler does not generate | |
| 51 | − * indexed addressing for it. | |
| 49 | + * Historically, a buffer_head was used to map a single block | |
| 50 | + * within a page, and of course as the unit of I/O through the | |
| 51 | + * filesystem and block layers. Nowadays the basic I/O unit | |
| 52 | + * is the bio, and buffer_heads are used for extracting block | |
| 53 | + * mappings (via a get_block_t call), for tracking state within | |
| 54 | + * a page (via a page_mapping) and for wrapping bio submission | |
| 55 | + * for backward compatibility reasons (e.g. submit_bh). | |
| 52 | 56 | */ |
| 53 | 57 | struct buffer_head { |
| 54 | − /* First cache line: */ | |
| 55 | 58 | unsigned long b_state; /* buffer state bitmap (see above) */ |
| 56 | 59 | struct buffer_head *b_this_page;/* circular list of page's buffers */ |
| 57 | 60 | struct page *b_page; /* the page this bh is mapped to */ |
| 58 | − atomic_t b_count; /* users using this block */ | |
| 59 | − u32 b_size; /* block size */ | |
| 60 | 61 | |
| 61 | − sector_t b_blocknr; /* block number */ | |
| 62 | − char *b_data; /* pointer to data block */ | |
| 62 | + sector_t b_blocknr; /* start block number */ | |
| 63 | + size_t b_size; /* size of mapping */ | |
| 64 | + char *b_data; /* pointer to data within the page */ | |
| 63 | 65 | |
| 64 | 66 | struct block_device *b_bdev; |
| 65 | 67 | bh_end_io_t *b_end_io; /* I/O completion */ |
| 66 | 68 | void *b_private; /* reserved for b_end_io */ |
| 67 | 69 | struct list_head b_assoc_buffers; /* associated with another mapping */ |
| 70 | + atomic_t b_count; /* users using this buffer_head */ | |
| 68 | 71 | }; |
| 69 | 72 | |
| 70 | 73 | /* |