linux-kernel - Re: [PATCH v3 2/6] fat: add fat

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Message-ID: <87mwi8x27b.fsf@devron.myhome.or.jp>
Date:	Mon, 03 Feb 2014 13:14:16 +0900
From:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To:	Namjae Jeon <linkinjeon@...il.com>
Cc:	akpm@...ux-foundation.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Namjae Jeon <namjae.jeon@...sung.com>,
	Amit Sahrawat <a.sahrawat@...sung.com>
Subject: Re: [PATCH v3 2/6] fat: add fat_fallocate operation


Sorry for long delay.

Namjae Jeon <linkinjeon@...il.com> writes:

> +	if (mode & FALLOC_FL_KEEP_SIZE) {
> +		/* First compute the number of clusters to be allocated */
> +		mm_bytes = offset + len - round_up(MSDOS_I(inode)->mmu_private,
> +			sbi->cluster_size);

This should use ->i_disksize?

[...]

> +		/* Release unwritten fallocated blocks on inode eviction. */
> +		if (MSDOS_I(inode)->mmu_private < MSDOS_I(inode)->i_disksize) {
> +			int err;
> +			fat_truncate_blocks(inode, MSDOS_I(inode)->mmu_private);
> +			/* Fallocate results in updating the i_start/iogstart
> +			 * for the zero byte file. So, make it return to
> +			 * original state during evict and commit it
> +			 * synchrnously to avoid any corruption on the next
> +			 * access to the cluster chain for the file.
> +			 */
> +			err = fat_sync_inode(inode);

Ah, good catch. We have to update i_size. I was forgetting about this.
Well, sync inode unconditionally would not be good. Maybe, we better to
use __fat_write_inode() with inode_needs_sync() or such.
-- 
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
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