linux-ext4 - Re: [PATCH] fs-verity: use mempool for hash requests

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Date:   Mon, 13 Jan 2020 19:28:44 -0500
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Eric Biggers <ebiggers@...nel.org>
Cc:     linux-fscrypt@...r.kernel.org, linux-ext4@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [PATCH] fs-verity: use mempool for hash requests

On Tue, Dec 31, 2019 at 11:55:45AM -0600, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@...gle.com>
> 
> When initializing an fs-verity hash algorithm, also initialize a mempool
> that contains a single preallocated hash request object.  Then replace
> the direct calls to ahash_request_alloc() and ahash_request_free() with
> allocating and freeing from this mempool.
> 
> This eliminates the possibility of the allocation failing, which is
> desirable for the I/O path.
> 
> This doesn't cause deadlocks because there's no case where multiple hash
> requests are needed at a time to make forward progress.
> 
> Signed-off-by: Eric Biggers <ebiggers@...gle.com>

Looks good; feel free to add:

Reviewed-by: Theodore Ts'o <tytso@....edu>