From: Yu Kuai <yukuai1@huaweicloud.com>
To: Matthew Wilcox <willy@infradead.org>, Yu Kuai <yukuai1@huaweicloud.com>
Cc: axboe@kernel.dk, roger.pau@citrix.com, colyli@suse.de,
kent.overstreet@gmail.com, joern@lazybastard.org,
miquel.raynal@bootlin.com, richard@nod.at, vigneshr@ti.com,
sth@linux.ibm.com, hoeppner@linux.ibm.com, hca@linux.ibm.com,
gor@linux.ibm.com, agordeev@linux.ibm.com, jejb@linux.ibm.com,
martin.petersen@oracle.com, clm@fb.com, josef@toxicpanda.com,
dsterba@suse.com, nico@fluxnic.net, xiang@kernel.org,
chao@kernel.org, tytso@mit.edu, adilger.kernel@dilger.ca,
agruenba@redhat.com, jack@suse.com, konishi.ryusuke@gmail.com,
akpm@linux-foundation.org, hare@suse.de, p.raghav@samsung.com,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
xen-devel@lists.xenproject.org, linux-bcache@vger.kernel.org,
linux-mtd@lists.infradead.org, linux-s390@vger.kernel.org,
linux-scsi@vger.kernel.org, linux-bcachefs@vger.kernel.org,
linux-btrfs@vger.kernel.org, linux-erofs@lists.ozlabs.org,
linux-ext4@vger.kernel.org, gfs2@lists.linux.dev,
linux-nilfs@vger.kernel.org, yi.zhang@huawei.com,
yangerkun@huawei.com, "yukuai (C)" <yukuai3@huawei.com>
Subject: Re: [PATCH -next RFC 01/14] block: add some bdev apis
Date: Thu, 7 Dec 2023 10:45:13 +0800 [thread overview]
Message-ID: <d195aba8-7b89-698f-b7a0-06b87ae01c21@huaweicloud.com> (raw)
In-Reply-To: <ZXCMJ9skAAgPm4z3@casper.infradead.org>
Hi,
在 2023/12/06 22:58, Matthew Wilcox 写道:
> On Tue, Dec 05, 2023 at 08:37:15PM +0800, Yu Kuai wrote:
>> +struct folio *bdev_read_folio(struct block_device *bdev, pgoff_t index)
>> +{
>> + return read_mapping_folio(bdev->bd_inode->i_mapping, index, NULL);
>> +}
>> +EXPORT_SYMBOL_GPL(bdev_read_folio);
>
> I'm coming to the opinion that 'index' is the wrong parameter here.
> Looking through all the callers of bdev_read_folio() in this patchset,
> they all have a position in bytes, and they all convert it to
> index for this call. The API should probably be:
>
> struct folio *bdev_read_folio(struct block_device *bdev, loff_t pos)
> {
> return read_mapping_folio(bdev->bd_inode->i_mapping,
> pos / PAGE_SIZE, NULL);
> }
Thanks for reviewing this patchset! Okay, I'll convert to pass in "pos"
in v2.
>
> ... and at some point, we'll get round to converting read_mapping_folio()
> to take its argument in loff_t.
>
> Similiarly for these two APIs:
>
>> +struct folio *bdev_read_folio_gfp(struct block_device *bdev, pgoff_t index,
>> + gfp_t gfp)
>> +struct folio *bdev_get_folio(struct block_device *bdev, pgoff_t index)
>
>> +struct folio *bdev_find_or_create_folio(struct block_device *bdev,
>> + pgoff_t index, gfp_t gfp)
>> +{
>> + return __filemap_get_folio(bdev->bd_inode->i_mapping, index,
>> + FGP_LOCK | FGP_ACCESSED | FGP_CREAT, gfp);
>> +}
>> +EXPORT_SYMBOL_GPL(bdev_find_or_create_folio);
>
> This one probably shouldn't exist. I've been converting callers of
> find_or_create_page() to call __filemap_get_folio; I suspect we
> should expose a __bdev_get_folio and have the callers use the FGP
> arguments directly, but I'm open to other opinions here.
If nobody against this, I will expose single __bdev_get_folio() to use
in v2.
>
>> +void bdev_sync_readahead(struct block_device *bdev, struct file_ra_state *ra,
>> + struct file *file, pgoff_t index,
>> + unsigned long req_count)
>> +{
>> + struct file_ra_state tmp_ra = {};
>> +
>> + if (!ra) {
>> + ra = &tmp_ra;
>> + file_ra_state_init(ra, bdev->bd_inode->i_mapping);
>> + }
>> + page_cache_sync_readahead(bdev->bd_inode->i_mapping, ra, file, index,
>> + req_count);
>> +}
>
> I think the caller should always be passing in a valid file_ra_state.
> It's only cramfs that doesn't have one, and it really should!
> Not entirely sure about the arguments here; part of me says "bytes",
> but this is weird enough to maybe take arguments in pages.
In fact, bdev_sync_readahead() is only called for cramfs and ext4.
For ext4 it's used in ext4_readdir() so there is valid file_ra_state.
Hoever, for cramfs it's used in cramfs_read(), and cramfs_read() is used
for:
1) cramfs_read_folio
2) cramfs_readdir
3) cramfs_lookup
4) cramfs_read_super
Looks like it's easy to pass in valid file_ra_state() for 1) and 2),
however, I don't see an easy way to do this for 3) and 4).
Thanks,
Kuai
>
> .
>
next prev parent reply other threads:[~2023-12-07 2:45 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-05 12:37 [PATCH -next RFC 00/14] block: don't access bd_inode directly from other modules Yu Kuai
2023-12-05 12:37 ` [PATCH -next RFC 01/14] block: add some bdev apis Yu Kuai
2023-12-05 17:03 ` Bart Van Assche
2023-12-06 6:14 ` Christoph Hellwig
2023-12-06 6:50 ` Yu Kuai
2023-12-06 7:20 ` Christoph Hellwig
2023-12-06 17:50 ` Theodore Ts'o
2023-12-06 17:57 ` Christoph Hellwig
2023-12-06 14:58 ` Matthew Wilcox
2023-12-07 2:45 ` Yu Kuai [this message]
2023-12-05 12:37 ` [PATCH -next RFC 02/14] xen/blkback: use bdev api in xen_update_blkif_status() Yu Kuai
2023-12-06 5:55 ` Christoph Hellwig
2023-12-06 6:56 ` Yu Kuai
2023-12-06 7:21 ` Christoph Hellwig
2023-12-05 12:37 ` [PATCH -next RFC 03/14] bcache: use bdev api in read_super() Yu Kuai
2023-12-05 12:37 ` [PATCH -next RFC 04/14] mtd: block2mtd: use bdev apis Yu Kuai
2023-12-05 12:37 ` [PATCH -next RFC 05/14] s390/dasd: use bdev api in dasd_format() Yu Kuai
2023-12-05 12:37 ` [PATCH -next RFC 06/14] scsicam: use bdev api in scsi_bios_ptable() Yu Kuai
2023-12-05 12:37 ` [PATCH -next RFC 07/14] bcachefs: remove dead function bdev_sectors() Yu Kuai
2023-12-05 12:37 ` [PATCH -next RFC 08/14] btrfs: use bdev apis Yu Kuai
2023-12-05 12:37 ` [PATCH -next RFC 09/14] cramfs: use bdev apis in cramfs_blkdev_read() Yu Kuai
2023-12-05 12:37 ` [PATCH -next RFC 10/14] erofs: use bdev api Yu Kuai
2023-12-05 12:37 ` [PATCH -next RFC 11/14] ext4: use bdev apis Yu Kuai
2023-12-05 12:38 ` [PATCH -next RFC 12/14] jbd2: " Yu Kuai
2023-12-05 12:39 ` [PATCH -next RFC 13/14] gfs2: use bdev api Yu Kuai
2023-12-05 12:39 ` [PATCH -next RFC 14/14] nilfs2: use bdev api in nilfs_attach_log_writer() Yu Kuai
2023-12-06 5:54 ` [PATCH -next RFC 00/14] block: don't access bd_inode directly from other modules Christoph Hellwig
2023-12-06 6:06 ` Yu Kuai
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