From: "Kirill A. Shutemov" Subject: [PATCHv1, RFC 22/33] fs: make block_write_{begin,end}() be able to handle huge pages Date: Tue, 26 Jul 2016 03:35:24 +0300 Message-ID: <1469493335-3622-23-git-send-email-kirill.shutemov@linux.intel.com> References: <1469493335-3622-1-git-send-email-kirill.shutemov@linux.intel.com> Cc: Alexander Viro , Hugh Dickins , Andrea Arcangeli , Andrew Morton , Dave Hansen , Vlastimil Babka , Matthew Wilcox , Ross Zwisler , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org, "Kirill A. Shutemov" To: "Theodore Ts'o" , Andreas Dilger , Jan Kara Return-path: In-Reply-To: <1469493335-3622-1-git-send-email-kirill.shutemov@linux.intel.com> Sender: owner-linux-mm@kvack.org List-Id: linux-ext4.vger.kernel.org It's more or less straight-forward. Most changes are around getting offset/len withing page right and zero out desired part of the page. Signed-off-by: Kirill A. Shutemov --- fs/buffer.c | 53 +++++++++++++++++++++++++++++++---------------------- 1 file changed, 31 insertions(+), 22 deletions(-) diff --git a/fs/buffer.c b/fs/buffer.c index 9ca197a924eb..edd0971f9f95 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -1870,21 +1870,21 @@ void page_zero_new_buffers(struct page *page, unsigned from, unsigned to) do { block_end = block_start + bh->b_size; - if (buffer_new(bh)) { - if (block_end > from && block_start < to) { - if (!PageUptodate(page)) { - unsigned start, size; + if (buffer_new(bh) && block_end > from && block_start < to) { + if (!PageUptodate(page)) { + unsigned start, size; - start = max(from, block_start); - size = min(to, block_end) - start; + start = max(from, block_start); + size = min(to, block_end) - start; - zero_user(page, start, size); - set_buffer_uptodate(bh); - } - - clear_buffer_new(bh); - mark_buffer_dirty(bh); + zero_user(page + block_start / PAGE_SIZE, + start % PAGE_SIZE, + size % PAGE_SIZE); + set_buffer_uptodate(bh); } + + clear_buffer_new(bh); + mark_buffer_dirty(bh); } block_start = block_end; @@ -1950,18 +1950,20 @@ iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh, int __block_write_begin_int(struct page *page, loff_t pos, unsigned len, get_block_t *get_block, struct iomap *iomap) { - unsigned from = pos & (PAGE_SIZE - 1); - unsigned to = from + len; - struct inode *inode = page->mapping->host; + unsigned from, to; + struct inode *inode = page_mapping(page)->host; unsigned block_start, block_end; sector_t block; int err = 0; unsigned blocksize, bbits; struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; + page = compound_head(page); + from = pos & ~hpage_mask(page); + to = from + len; BUG_ON(!PageLocked(page)); - BUG_ON(from > PAGE_SIZE); - BUG_ON(to > PAGE_SIZE); + BUG_ON(from > hpage_size(page)); + BUG_ON(to > hpage_size(page)); BUG_ON(from > to); head = create_page_buffers(page, inode, 0); @@ -2001,10 +2003,15 @@ int __block_write_begin_int(struct page *page, loff_t pos, unsigned len, mark_buffer_dirty(bh); continue; } - if (block_end > to || block_start < from) - zero_user_segments(page, - to, block_end, - block_start, from); + if (block_end > to || block_start < from) { + BUG_ON(to - from > PAGE_SIZE); + zero_user_segments(page + + block_start / PAGE_SIZE, + to % PAGE_SIZE, + block_end % PAGE_SIZE, + block_start % PAGE_SIZE, + from % PAGE_SIZE); + } continue; } } @@ -2048,6 +2055,7 @@ static int __block_commit_write(struct inode *inode, struct page *page, unsigned blocksize; struct buffer_head *bh, *head; + VM_BUG_ON_PAGE(PageTail(page), page); bh = head = page_buffers(page); blocksize = bh->b_size; @@ -2114,7 +2122,8 @@ int block_write_end(struct file *file, struct address_space *mapping, struct inode *inode = mapping->host; unsigned start; - start = pos & (PAGE_SIZE - 1); + page = compound_head(page); + start = pos & ~hpage_mask(page); if (unlikely(copied < len)) { /* -- 2.8.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org