ext4_ext_zeroout_mem() zero out blocks in mem.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@xxxxxxxxx>
---
fs/ext4/extents.c | 70 +++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 70 insertions(+), 0 deletions(-)
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 9e7c7b3..30663b6 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2555,6 +2555,76 @@ static int ext4_ext_zeroout(struct inode *inode, struct ext4_extent *ex)
}
/*
+ * ext4_ext_zeroout_mem() zero specified pages in page cache.
+ * this function is used by ext4_ext_convert_to_initialized() to
+ * zeroout small extents.
+ *
+ * @inode: the file inode
+ * @ex: the extent to be zeroout
+ *
+ * return 0 on success
+ */
+static int ext4_ext_zeroout_mem(struct inode *inode,
+ struct ext4_extent *ex)
+{
+ ext4_fsblk_t pblk;
+ ext4_lblk_t lblk;
+ ext4_lblk_t end;
+ struct page *page;
+ struct buffer_head *bh;
+ struct block_device *bdev;
+ pgoff_t index;
+ unsigned blocksize, blks_per_page_bits;
+
+ bdev = inode->i_sb->s_bdev;
+
+ blocksize = 1 << inode->i_blkbits;
+ blks_per_page_bits = PAGE_CACHE_SHIFT - inode->i_blkbits;
+
+ pblk = ext4_ext_pblock(ex);
+ lblk = le32_to_cpu(ex->ee_block);
+ end = lblk + ext4_ext_get_actual_len(ex);
+
+ while (lblk < end) {
+ struct ext4_extent ext;
+ char *kaddr;
+
+ /* grab page */
+ index = lblk >> blks_per_page_bits;
+ page = grab_cache_page_write_begin(inode->i_mapping,
+ index, AOP_FLAG_NOFS);
+ if (!page) {
+ ext.ee_block = cpu_to_le32(lblk);
+ ext.ee_len = cpu_to_le16(end - lblk);
+ ext4_ext_store_pblock(&ext, pblk);
+ return ext4_ext_zeroout(inode, &ext);
+ }
+
+ /* map buffers, mark dirty */
+ if (!page_has_buffers(page))
+ create_empty_buffers(page, blocksize, 0);
+
+ kaddr = kmap_atomic(page, KM_USER0);
+ bh = page_buffers(page);
+ do {
+ unmap_underlying_metadata(bdev, pblk);
+ memset(kaddr, 0, blocksize);
+ map_bh(bh, inode->i_sb, pblk++);
+ set_buffer_uptodate(bh);
+ mark_buffer_dirty(bh);
+ bh = bh->b_this_page;
+ lblk++;
+ } while (bh != page_buffers(page) && lblk < end);
+ kunmap_atomic(kaddr, KM_USER0);
+
+ unlock_page(page);
+ page_cache_release(page);
+ }
+
+ return 0;
+}
+
+/*
* used by extent splitting.
*/
#define EXT4_EXT_MAY_ZEROOUT 0x1 /* safe to zeroout if split fails \
--
1.7.4.4
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