From: "Kirill A. Shutemov" Subject: [PATCHv1, RFC 25/33] ext4: make ext4_mpage_readpages() hugepage-aware Date: Tue, 26 Jul 2016 03:35:27 +0300 Message-ID: <1469493335-3622-26-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 This patch modifies ext4_mpage_readpages() to deal with huge pages. We read out 2M at once, so we have to alloc (HPAGE_PMD_NR * blocks_per_page) sector_t for that. I'm not entirely happy with kmalloc in this codepath, but don't see any other option. Signed-off-by: Kirill A. Shutemov --- fs/ext4/readpage.c | 38 ++++++++++++++++++++++++++++++++------ 1 file changed, 32 insertions(+), 6 deletions(-) diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c index a81b829d56de..6d7cbddceeb2 100644 --- a/fs/ext4/readpage.c +++ b/fs/ext4/readpage.c @@ -104,12 +104,12 @@ int ext4_mpage_readpages(struct address_space *mapping, struct inode *inode = mapping->host; const unsigned blkbits = inode->i_blkbits; - const unsigned blocks_per_page = PAGE_SIZE >> blkbits; const unsigned blocksize = 1 << blkbits; sector_t block_in_file; sector_t last_block; sector_t last_block_in_file; - sector_t blocks[MAX_BUF_PER_PAGE]; + sector_t blocks_on_stack[MAX_BUF_PER_PAGE]; + sector_t *blocks = blocks_on_stack; unsigned page_block; struct block_device *bdev = inode->i_sb->s_bdev; int length; @@ -122,8 +122,9 @@ int ext4_mpage_readpages(struct address_space *mapping, map.m_flags = 0; for (; nr_pages; nr_pages--) { - int fully_mapped = 1; - unsigned first_hole = blocks_per_page; + int fully_mapped = 1, nr = nr_pages; + unsigned blocks_per_page = PAGE_SIZE >> blkbits; + unsigned first_hole; prefetchw(&page->flags); if (pages) { @@ -138,10 +139,31 @@ int ext4_mpage_readpages(struct address_space *mapping, goto confused; block_in_file = (sector_t)page->index << (PAGE_SHIFT - blkbits); - last_block = block_in_file + nr_pages * blocks_per_page; + + if (PageTransHuge(page)) { + BUILD_BUG_ON(BIO_MAX_PAGES < HPAGE_PMD_NR); + nr = HPAGE_PMD_NR * blocks_per_page; + /* XXX: need a better solution ? */ + blocks = kmalloc(sizeof(sector_t) * nr, GFP_NOFS); + if (!blocks) { + if (pages) { + delete_from_page_cache(page); + goto next_page; + } + return -ENOMEM; + } + + blocks_per_page *= HPAGE_PMD_NR; + last_block = block_in_file + blocks_per_page; + } else { + blocks = blocks_on_stack; + last_block = block_in_file + nr * blocks_per_page; + } + last_block_in_file = (i_size_read(inode) + blocksize - 1) >> blkbits; if (last_block > last_block_in_file) last_block = last_block_in_file; + first_hole = blocks_per_page; page_block = 0; /* @@ -213,6 +235,8 @@ int ext4_mpage_readpages(struct address_space *mapping, } } if (first_hole != blocks_per_page) { + if (PageTransHuge(page)) + goto confused; zero_user_segment(page, first_hole << blkbits, PAGE_SIZE); if (first_hole == 0) { @@ -248,7 +272,7 @@ int ext4_mpage_readpages(struct address_space *mapping, goto set_error_page; } bio = bio_alloc(GFP_KERNEL, - min_t(int, nr_pages, BIO_MAX_PAGES)); + min_t(int, nr, BIO_MAX_PAGES)); if (!bio) { if (ctx) fscrypt_release_ctx(ctx); @@ -289,5 +313,7 @@ int ext4_mpage_readpages(struct address_space *mapping, BUG_ON(pages && !list_empty(pages)); if (bio) submit_bio(bio); + if (blocks != blocks_on_stack) + kfree(blocks); return 0; } -- 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