diff options
Diffstat (limited to 'fs/buffer.c')
| -rw-r--r-- | fs/buffer.c | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/fs/buffer.c b/fs/buffer.c index af5776da814a..f8beca55240a 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -43,6 +43,7 @@ #include <linux/bitops.h> #include <linux/mpage.h> #include <linux/bit_spinlock.h> +#include <linux/pagevec.h> #include <trace/events/block.h> static int fsync_buffers_list(spinlock_t *lock, struct list_head *list); @@ -1636,6 +1637,81 @@ void unmap_underlying_metadata(struct block_device *bdev, sector_t block) } EXPORT_SYMBOL(unmap_underlying_metadata); +/** + * clean_bdev_aliases: clean a range of buffers in block device + * @bdev: Block device to clean buffers in + * @block: Start of a range of blocks to clean + * @len: Number of blocks to clean + * + * We are taking a range of blocks for data and we don't want writeback of any + * buffer-cache aliases starting from return from this function and until the + * moment when something will explicitly mark the buffer dirty (hopefully that + * will not happen until we will free that block ;-) We don't even need to mark + * it not-uptodate - nobody can expect anything from a newly allocated buffer + * anyway. We used to use unmap_buffer() for such invalidation, but that was + * wrong. We definitely don't want to mark the alias unmapped, for example - it + * would confuse anyone who might pick it with bread() afterwards... + * + * Also.. Note that bforget() doesn't lock the buffer. So there can be + * writeout I/O going on against recently-freed buffers. We don't wait on that + * I/O in bforget() - it's more efficient to wait on the I/O only if we really + * need to. That happens here. + */ +void clean_bdev_aliases(struct block_device *bdev, sector_t block, sector_t len) +{ + struct inode *bd_inode = bdev->bd_inode; + struct address_space *bd_mapping = bd_inode->i_mapping; + struct pagevec pvec; + pgoff_t index = block >> (PAGE_SHIFT - bd_inode->i_blkbits); + pgoff_t end; + int i; + struct buffer_head *bh; + struct buffer_head *head; + + end = (block + len - 1) >> (PAGE_SHIFT - bd_inode->i_blkbits); + pagevec_init(&pvec, 0); + while (index <= end && pagevec_lookup(&pvec, bd_mapping, index, + min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) { + for (i = 0; i < pagevec_count(&pvec); i++) { + struct page *page = pvec.pages[i]; + + index = page->index; + if (index > end) + break; + if (!page_has_buffers(page)) + continue; + /* + * We use page lock instead of bd_mapping->private_lock + * to pin buffers here since we can afford to sleep and + * it scales better than a global spinlock lock. + */ + lock_page(page); + /* Recheck when the page is locked which pins bhs */ + if (!page_has_buffers(page)) + goto unlock_page; + head = page_buffers(page); + bh = head; + do { + if (!buffer_mapped(bh)) + goto next; + if (bh->b_blocknr >= block + len) + break; + clear_buffer_dirty(bh); + wait_on_buffer(bh); + clear_buffer_req(bh); +next: + bh = bh->b_this_page; + } while (bh != head); +unlock_page: + unlock_page(page); + } + pagevec_release(&pvec); + cond_resched(); + index++; + } +} +EXPORT_SYMBOL(clean_bdev_aliases); + /* * Size is a power-of-two in the range 512..PAGE_SIZE, * and the case we care about most is PAGE_SIZE. |