linux-kernel - [PATCHv5 27/36] ext4: handle huge pages in __ext4_block_zero_page

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Message-Id: <20161129112304.90056-28-kirill.shutemov@linux.intel.com>
Date:   Tue, 29 Nov 2016 14:22:55 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     "Theodore Ts'o" <tytso@....edu>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Jan Kara <jack@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        Hugh Dickins <hughd@...gle.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Matthew Wilcox <willy@...radead.org>,
        Ross Zwisler <ross.zwisler@...ux.intel.com>,
        linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-block@...r.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCHv5 27/36] ext4: handle huge pages in __ext4_block_zero_page_range()

As the function handles zeroing range only within one block, the
required changes are trivial, just remove assuption on page size.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
 fs/ext4/inode.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 387aa857770b..d3143dfe9962 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3776,7 +3776,7 @@ static int __ext4_block_zero_page_range(handle_t *handle,
 		struct address_space *mapping, loff_t from, loff_t length)
 {
 	ext4_fsblk_t index = from >> PAGE_SHIFT;
-	unsigned offset = from & (PAGE_SIZE-1);
+	unsigned offset;
 	unsigned blocksize, pos;
 	ext4_lblk_t iblock;
 	struct inode *inode = mapping->host;
@@ -3789,6 +3789,9 @@ static int __ext4_block_zero_page_range(handle_t *handle,
 	if (!page)
 		return -ENOMEM;
 
+	page = compound_head(page);
+	offset = from & ~hpage_mask(page);
+
 	blocksize = inode->i_sb->s_blocksize;
 
 	iblock = index << (PAGE_SHIFT - inode->i_sb->s_blocksize_bits);
@@ -3845,7 +3848,7 @@ static int __ext4_block_zero_page_range(handle_t *handle,
 		if (err)
 			goto unlock;
 	}
-	zero_user(page, offset, length);
+	zero_user(page + offset / PAGE_SIZE, offset % PAGE_SIZE, length);
 	BUFFER_TRACE(bh, "zeroed end of block");
 
 	if (ext4_should_journal_data(inode)) {
-- 
2.10.2