ext4: properly sync file size update after O_SYNC direct IO (52c6fec9) · Commits · EulixOS / Software / Kernel

fs/ext4/file.c

+65 −87

Original line number	Diff line number	Diff line
		@@ -283,80 +283,38 @@ static ssize_t ext4_buffered_write_iter(struct kiocb *iocb,
		}

		static ssize_t ext4_handle_inode_extension(struct inode *inode, loff_t offset,
		ssize_t written, size_t count)
		ssize_t count)
		{
		handle_t *handle;
		bool truncate = false;
		u8 blkbits = inode->i_blkbits;
		ext4_lblk_t written_blk, end_blk;
		int ret;

		/*
		* Note that EXT4_I(inode)->i_disksize can get extended up to
		* inode->i_size while the I/O was running due to writeback of delalloc
		* blocks. But, the code in ext4_iomap_alloc() is careful to use
		* zeroed/unwritten extents if this is possible; thus we won't leave
		* uninitialized blocks in a file even if we didn't succeed in writing
		* as much as we intended.
		*/
		WARN_ON_ONCE(i_size_read(inode) < EXT4_I(inode)->i_disksize);
		if (offset + count <= EXT4_I(inode)->i_disksize) {
		/*
		* We need to ensure that the inode is removed from the orphan
		* list if it has been added prematurely, due to writeback of
		* delalloc blocks.
		*/
		if (!list_empty(&EXT4_I(inode)->i_orphan) && inode->i_nlink) {
		lockdep_assert_held_write(&inode->i_rwsem);
		handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);

		if (IS_ERR(handle)) {
		ext4_orphan_del(NULL, inode);
		if (IS_ERR(handle))
		return PTR_ERR(handle);
		}

		ext4_orphan_del(handle, inode);
		if (ext4_update_inode_size(inode, offset + count)) {
		int ret = ext4_mark_inode_dirty(handle, inode);
		if (unlikely(ret)) {
		ext4_journal_stop(handle);
		return ret;
		}

		return written;
		}

		if (written < 0)
		goto truncate;

		handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
		if (IS_ERR(handle)) {
		written = PTR_ERR(handle);
		goto truncate;
		}

		if (ext4_update_inode_size(inode, offset + written)) {
		ret = ext4_mark_inode_dirty(handle, inode);
		if (unlikely(ret)) {
		written = ret;
		if (inode->i_nlink)
		ext4_orphan_del(handle, inode);
		ext4_journal_stop(handle);
		goto truncate;
		}
		}

		/*
		* We may need to truncate allocated but not written blocks beyond EOF.
		*/
		written_blk = ALIGN(offset + written, 1 << blkbits);
		end_blk = ALIGN(offset + count, 1 << blkbits);
		if (written_blk < end_blk && ext4_can_truncate(inode))
		truncate = true;
		return count;
		}

		/*
		* Remove the inode from the orphan list if it has been extended and
		* everything went OK.
		* Clean up the inode after DIO or DAX extending write has completed and the
		* inode size has been updated using ext4_handle_inode_extension().
		*/
		if (!truncate && inode->i_nlink)
		ext4_orphan_del(handle, inode);
		ext4_journal_stop(handle);

		if (truncate) {
		truncate:
		static void ext4_inode_extension_cleanup(struct inode *inode, ssize_t count)
		{
		lockdep_assert_held_write(&inode->i_rwsem);
		if (count < 0) {
		ext4_truncate_failed_write(inode);
		/*
		* If the truncate operation failed early, then the inode may
		@@ -365,9 +323,28 @@ static ssize_t ext4_handle_inode_extension(struct inode *inode, loff_t offset,
		*/
		if (inode->i_nlink)
		ext4_orphan_del(NULL, inode);
		return;
		}
		/*
		* If i_disksize got extended due to writeback of delalloc blocks while
		* the DIO was running we could fail to cleanup the orphan list in
		* ext4_handle_inode_extension(). Do it now.
		*/
		if (!list_empty(&EXT4_I(inode)->i_orphan) && inode->i_nlink) {
		handle_t *handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);

		return written;
		if (IS_ERR(handle)) {
		/*
		* The write has successfully completed. Not much to
		* do with the error here so just cleanup the orphan
		* list and hope for the best.
		*/
		ext4_orphan_del(NULL, inode);
		return;
		}
		ext4_orphan_del(handle, inode);
		ext4_journal_stop(handle);
		}
		}

		static int ext4_dio_write_end_io(struct kiocb *iocb, ssize_t size,
		@@ -376,31 +353,22 @@ static int ext4_dio_write_end_io(struct kiocb *iocb, ssize_t size,
		loff_t pos = iocb->ki_pos;
		struct inode *inode = file_inode(iocb->ki_filp);

		if (error)
		return error;

		if (size && flags & IOMAP_DIO_UNWRITTEN) {
		if (!error && size && flags & IOMAP_DIO_UNWRITTEN)
		error = ext4_convert_unwritten_extents(NULL, inode, pos, size);
		if (error < 0)
		if (error)
		return error;
		}
		/*
		* If we are extending the file, we have to update i_size here before
		* page cache gets invalidated in iomap_dio_rw(). Otherwise racing
		* buffered reads could zero out too much from page cache pages. Update
		* of on-disk size will happen later in ext4_dio_write_iter() where
		* we have enough information to also perform orphan list handling etc.
		* Note that we perform all extending writes synchronously under
		* i_rwsem held exclusively so i_size update is safe here in that case.
		* If the write was not extending, we cannot see pos > i_size here
		* because operations reducing i_size like truncate wait for all
		* outstanding DIO before updating i_size.
		* Note that EXT4_I(inode)->i_disksize can get extended up to
		* inode->i_size while the I/O was running due to writeback of delalloc
		* blocks. But the code in ext4_iomap_alloc() is careful to use
		* zeroed/unwritten extents if this is possible; thus we won't leave
		* uninitialized blocks in a file even if we didn't succeed in writing
		* as much as we intended.
		*/
		pos += size;
		if (pos > i_size_read(inode))
		i_size_write(inode, pos);

		return 0;
		WARN_ON_ONCE(i_size_read(inode) < READ_ONCE(EXT4_I(inode)->i_disksize));
		if (pos + size <= READ_ONCE(EXT4_I(inode)->i_disksize))
		return size;
		return ext4_handle_inode_extension(inode, pos, size);
		}

		static const struct iomap_dio_ops ext4_dio_write_ops = {
		@@ -581,8 +549,16 @@ static ssize_t ext4_dio_write_iter(struct kiocb iocb, struct iov_iter from)
		if (ret == -ENOTBLK)
		ret = 0;

		if (extend)
		ret = ext4_handle_inode_extension(inode, offset, ret, count);
		if (extend) {
		/*
		* We always perform extending DIO write synchronously so by
		* now the IO is completed and ext4_handle_inode_extension()
		* was called. Cleanup the inode in case of error or race with
		* writeback of delalloc blocks.
		*/
		WARN_ON_ONCE(ret == -EIOCBQUEUED);
		ext4_inode_extension_cleanup(inode, ret);
		}

		out:
		if (ilock_shared)
		@@ -663,8 +639,10 @@ ext4_dax_write_iter(struct kiocb iocb, struct iov_iter from)

		ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);

		if (extend)
		ret = ext4_handle_inode_extension(inode, offset, ret, count);
		if (extend) {
		ret = ext4_handle_inode_extension(inode, offset, ret);
		ext4_inode_extension_cleanup(inode, ret);
		}
		out:
		inode_unlock(inode);
		if (ret > 0)