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d=pankajraghav.com; s=MBO0001; t=1719928888; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=J6W5uuHM9ZW/rEky4ztQshWxBTdgHKyHpuUWE6Z27TI=; b=dkYKV11weiLwFZR7c/DrT5d2a6fAJRM81tYaaNbCabxi3EXwnG32NzShMiXaGpk8PFHZ7j 1A+r2PDhFZKos+HXcuniuhlfbSi74LCBKFvW6a96siJGjAhy5jBd3D6XvqD7Tv0C8itl2c gD2P6mYzM7UoL5AhZ0uaMf0Itvldd/aFsUPi74ytaOuyzTfakrF6S6EYeKK7FH3o5Xlh9n 7SginUHFUNydqIR79xCnQr69PFDY38TKf42c+XaAv+MWyf3YTOPmY13kH13mvBChvBWBVX L4f5JbCaoF5xoYAjmpTuXhlsMtZptSkOOYHN28ZAJgZTwE4Jk81+EsFj1jx4bw== Date: Tue, 2 Jul 2024 14:01:23 +0000 From: "Pankaj Raghav (Samsung)" To: Christoph Hellwig Cc: david@fromorbit.com, willy@infradead.org, chandan.babu@oracle.com, djwong@kernel.org, brauner@kernel.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, yang@os.amperecomputing.com, linux-mm@kvack.org, john.g.garry@oracle.com, linux-fsdevel@vger.kernel.org, hare@suse.de, p.raghav@samsung.com, mcgrof@kernel.org, gost.dev@samsung.com, cl@os.amperecomputing.com, linux-xfs@vger.kernel.org, Zi Yan Subject: Re: [PATCH v8 06/10] iomap: fix iomap_dio_zero() for fs bs > system page size Message-ID: <20240702140123.emt2gz5kbigth2en@quentin> References: <20240625114420.719014-1-kernel@pankajraghav.com> <20240625114420.719014-7-kernel@pankajraghav.com> <20240702074203.GA29410@lst.de> <20240702101556.jdi5anyr3v5zngnv@quentin> <20240702120250.GA17373@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240702120250.GA17373@lst.de> X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 298AFC0080 X-Stat-Signature: j9gwyay4i8m7qc31kf6j49f14ofxyxbj X-Rspam-User: X-HE-Tag: 1719928893-354964 X-HE-Meta: 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 /2n4nEVG xPv4Xl0zVxDDdl19Kg6zCpuxOmZ2ef2hAJklH67qEpFWgpQ3a4VE5+5qO5w7nWkVx4MgMuaMlEI2X2aFWnXjcDod1qzjJhfI0gbhbhx16BuCIRZkn3+H7T5Bkm9+TQ+fD4YXU18THyMQojApUkFSXnnJWQFL4WhvCckjU8W7tj665Er4JQH6xAtIMUF/HK3iQCMmIRPeZ2wEPq+xLPnzHd+6Blb/0OVgO90IK7JuPME3XSjyTZ7ccNgHNsbk6OFeBO2fJ+Satilarw9I= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > > > A WARN_ON without actually erroring out here is highly dangerous. > > > > I agree but I think we decided that we are safe with 64k for now as fs > > that uses iomap will not have a block size > 64k. > > > > But this function needs some changes when we decide to go beyond 64k > > by returning error instead of not returning anything. > > Until then WARN_ON_ONCE would be a good stop gap for people developing > > the feature to go beyond 64k block size[1]. > > Sure, but please make it return an error and return that instead of > just warning and going beyond the allocated page. Does this make sense? diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c index 61d09d2364f7..14be34703588 100644 --- a/fs/iomap/direct-io.c +++ b/fs/iomap/direct-io.c @@ -240,16 +240,19 @@ void iomap_dio_bio_end_io(struct bio *bio) } EXPORT_SYMBOL_GPL(iomap_dio_bio_end_io); -static void iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio, +static int iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio, loff_t pos, unsigned len) { struct inode *inode = file_inode(dio->iocb->ki_filp); struct bio *bio; + if (!len) + return 0; /* * Max block size supported is 64k */ - WARN_ON_ONCE(len > ZERO_PAGE_64K_SIZE); + if (len > ZERO_PAGE_64K_SIZE) + return -EINVAL; bio = iomap_dio_alloc_bio(iter, dio, 1, REQ_OP_WRITE | REQ_SYNC | REQ_IDLE); fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits, @@ -260,6 +263,7 @@ static void iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio, __bio_add_page(bio, zero_page_64k, len, 0); iomap_dio_submit_bio(iter, dio, bio, pos); + return 0; } /* @@ -368,8 +372,10 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter, if (need_zeroout) { /* zero out from the start of the block to the write offset */ pad = pos & (fs_block_size - 1); - if (pad) - iomap_dio_zero(iter, dio, pos - pad, pad); + + ret = iomap_dio_zero(iter, dio, pos - pad, pad); + if (ret) + goto out; } /* @@ -443,7 +449,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter, /* zero out from the end of the write to the end of the block */ pad = pos & (fs_block_size - 1); if (pad) - iomap_dio_zero(iter, dio, pos, fs_block_size - pad); + ret = iomap_dio_zero(iter, dio, pos, fs_block_size - pad); } out: /* Undo iter limitation to current extent */ -- Pankaj