Commit 4df031ff authored by Zhang Yi's avatar Zhang Yi Committed by Theodore Ts'o
Browse files

ext4: check and update i_disksize properly 



After commit 3da40c7b ("ext4: only call ext4_truncate when size <=
isize"), i_disksize could always be updated to i_size in ext4_setattr(),
and we could sure that i_disksize <= i_size since holding inode lock and
if i_disksize < i_size there are delalloc writes pending in the range
upto i_size. If the end of the current write is <= i_size, there's no
need to touch i_disksize since writeback will push i_disksize upto
i_size eventually. So we can switch to check i_size instead of
i_disksize in ext4_da_write_end() when write to the end of the file.
we also could remove ext4_mark_inode_dirty() together because we defer
inode dirtying to generic_write_end() or ext4_da_write_inline_data_end().

Signed-off-by: default avatarZhang Yi <yi.zhang@huawei.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20210716122024.1105856-2-yi.zhang@huawei.com
parent b33d9f59

fs/ext4/inode.c

+18 −16
Original line number Diff line number Diff line
@@ -3084,35 +3084,37 @@ static int ext4_da_write_end(struct file *file, 
	end = start + copied - 1;



	/*

	 * generic_write_end() will run mark_inode_dirty() if i_size

	 * changes.  So let's piggyback the i_disksize mark_inode_dirty

	 * into that.

	 * Since we are holding inode lock, we are sure i_disksize <=

	 * i_size. We also know that if i_disksize < i_size, there are

	 * delalloc writes pending in the range upto i_size. If the end of

	 * the current write is <= i_size, there's no need to touch

	 * i_disksize since writeback will push i_disksize upto i_size

	 * eventually. If the end of the current write is > i_size and

	 * inside an allocated block (ext4_da_should_update_i_disksize()

	 * check), we need to update i_disksize here as neither

	 * ext4_writepage() nor certain ext4_writepages() paths not

	 * allocating blocks update i_disksize.

	 *

	 * Note that we defer inode dirtying to generic_write_end() /

	 * ext4_da_write_inline_data_end().

	 */

	new_i_size = pos + copied;

	if (copied && new_i_size > EXT4_I(inode)->i_disksize) {

	if (copied && new_i_size > inode->i_size) {

		if (ext4_has_inline_data(inode) ||

		    ext4_da_should_update_i_disksize(page, end)) {

		    ext4_da_should_update_i_disksize(page, end))

			ext4_update_i_disksize(inode, new_i_size);

			/* We need to mark inode dirty even if

			 * new_i_size is less that inode->i_size

			 * bu greater than i_disksize.(hint delalloc)

			 */

			ret = ext4_mark_inode_dirty(handle, inode);

		}

	}



	if (write_mode != CONVERT_INLINE_DATA &&

	    ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA) &&

	    ext4_has_inline_data(inode))

		ret2 = ext4_da_write_inline_data_end(inode, pos, len, copied,

		ret = ext4_da_write_inline_data_end(inode, pos, len, copied,

						     page);

	else

		ret2 = generic_write_end(file, mapping, pos, len, copied,

		ret = generic_write_end(file, mapping, pos, len, copied,

							page, fsdata);



	copied = ret2;

	if (ret2 < 0)

		ret = ret2;

	copied = ret;

	ret2 = ext4_journal_stop(handle);

	if (unlikely(ret2 && !ret))

		ret = ret2;