Re: [PATCH v6 24/31] ext4: defer i_disksize update while DISKSIZE_GROW_PENDING is set

[sashiko-bot@kernel.org]

> From: Zhang Yi <yi.zhang@huawei.com>
> 
> Operations like append allocate, zero range, and truncate update
> i_disksize directly. If the new i_disksize exceeds the original value
> while the zeroed EOF block is still awaiting writeback, metadata may be
> persisted before the zeroed data, exposing stale data on crash.
> 
> Defer i_disksize updates while EXT4_STATE_DISKSIZE_GROW_PENDING is set;
> the ioend worker for the pending block will advance i_disksize to i_size
> once the zeroed data is written back. The tradeoff is that i_disksize
> may lag i_size transiently, but this is observable only to callers that
> read i_disksize directly.
> 
> Introduce __ext4_set_i_disksize() to centralize the bit check for
> callers already holding i_data_sem (ext4_ext_truncate and
> ext4_set_inode_size), and refactor ext4_update_inode_size() to take
> i_data_sem itself and check the bit atomically with i_size_write(), so
> the ioend worker observes the latest i_size under the same lock.
> 
> Note that in the O_SYNC mode of ext4_do_fallocate() or
> ext4_zero_range(), we need to flush out pending blocks that can update
> i_disksize synchronously. This will be handled later, and
> EXT4_STATE_DISKSIZE_GROW_PENDING will also be set after everything is
> done.
> 
> Suggested-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Zhang Yi <yi.zhang@huawei.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260903123543.2302999-1-yi.zhang@huaweicloud.com?part=24