From: "Kirill A. Shutemov" Subject: [PATCHv1, RFC 21/33] fs: make block_read_full_page() be able to read huge page Date: Tue, 26 Jul 2016 03:35:23 +0300 Message-ID: <1469493335-3622-22-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 The approach is straight-forward: for compound pages we read out whole huge page. For huge page we cannot have array of buffer head pointers on stack -- it's 4096 pointers on x86-64 -- 'arr' is allocated with kmalloc() for huge pages. Signed-off-by: Kirill A. Shutemov --- fs/buffer.c | 22 +++++++++++++++++----- include/linux/buffer_head.h | 9 +++++---- include/linux/page-flags.h | 2 +- 3 files changed, 23 insertions(+), 10 deletions(-) diff --git a/fs/buffer.c b/fs/buffer.c index 193ef03401ed..9ca197a924eb 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -870,7 +870,7 @@ struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, try_again: head = NULL; - offset = PAGE_SIZE; + offset = hpage_size(page); while ((offset -= size) >= 0) { bh = alloc_buffer_head(GFP_NOFS); if (!bh) @@ -1466,7 +1466,7 @@ void set_bh_page(struct buffer_head *bh, struct page *page, unsigned long offset) { bh->b_page = page; - BUG_ON(offset >= PAGE_SIZE); + BUG_ON(offset >= hpage_size(page)); if (PageHighMem(page)) /* * This catches illegal uses and preserves the offset: @@ -2239,11 +2239,13 @@ int block_read_full_page(struct page *page, get_block_t *get_block) { struct inode *inode = page->mapping->host; sector_t iblock, lblock; - struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; + struct buffer_head *arr_on_stack[MAX_BUF_PER_PAGE]; + struct buffer_head *bh, *head, **arr = arr_on_stack; unsigned int blocksize, bbits; int nr, i; int fully_mapped = 1; + VM_BUG_ON_PAGE(PageTail(page), page); head = create_page_buffers(page, inode, 0); blocksize = head->b_size; bbits = block_size_bits(blocksize); @@ -2254,6 +2256,11 @@ int block_read_full_page(struct page *page, get_block_t *get_block) nr = 0; i = 0; + if (PageTransHuge(page)) { + arr = kmalloc(sizeof(struct buffer_head *) * HPAGE_PMD_NR * + MAX_BUF_PER_PAGE, GFP_NOFS); + } + do { if (buffer_uptodate(bh)) continue; @@ -2269,7 +2276,9 @@ int block_read_full_page(struct page *page, get_block_t *get_block) SetPageError(page); } if (!buffer_mapped(bh)) { - zero_user(page, i * blocksize, blocksize); + zero_user(page + (i * blocksize / PAGE_SIZE), + i * blocksize % PAGE_SIZE, + blocksize); if (!err) set_buffer_uptodate(bh); continue; @@ -2295,7 +2304,7 @@ int block_read_full_page(struct page *page, get_block_t *get_block) if (!PageError(page)) SetPageUptodate(page); unlock_page(page); - return 0; + goto out; } /* Stage two: lock the buffers */ @@ -2317,6 +2326,9 @@ int block_read_full_page(struct page *page, get_block_t *get_block) else submit_bh(REQ_OP_READ, 0, bh); } +out: + if (arr != arr_on_stack) + kfree(arr); return 0; } EXPORT_SYMBOL(block_read_full_page); diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index ebbacd14d450..2389e8fd6127 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -131,13 +131,14 @@ BUFFER_FNS(Meta, meta) BUFFER_FNS(Prio, prio) BUFFER_FNS(Defer_Completion, defer_completion) -#define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK) +#define bh_offset(bh) ((unsigned long)(bh)->b_data & ~hpage_mask(bh->b_page)) /* If we *know* page->private refers to buffer_heads */ -#define page_buffers(page) \ +#define page_buffers(__page) \ ({ \ - BUG_ON(!PagePrivate(page)); \ - ((struct buffer_head *)page_private(page)); \ + struct page *p = compound_head(__page); \ + BUG_ON(!PagePrivate(p)); \ + ((struct buffer_head *)page_private(p)); \ }) #define page_has_buffers(page) PagePrivate(page) diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index de90abb7c84e..89f0e9f26694 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -730,7 +730,7 @@ static inline void ClearPageSlabPfmemalloc(struct page *page) */ static inline int page_has_private(struct page *page) { - return !!(page->flags & PAGE_FLAGS_PRIVATE); + return !!(compound_head(page)->flags & PAGE_FLAGS_PRIVATE); } #undef PF_ANY -- 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