From: Jan Kara <jack@suse.cz>
To: Matthew Wilcox <willy@infradead.org>
Cc: Yu Kuai <yukuai1@huaweicloud.com>,
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, viro@zeniv.linux.org.uk, brauner@kernel.org,
nico@fluxnic.net, xiang@kernel.org, chao@kernel.org,
tytso@mit.edu, adilger.kernel@dilger.ca, 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-fsdevel@vger.kernel.org, linux-erofs@lists.ozlabs.org,
linux-ext4@vger.kernel.org, linux-nilfs@vger.kernel.org,
yukuai3@huawei.com, yi.zhang@huawei.com, yangerkun@huawei.com
Subject: Re: [PATCH RFC v3 for-6.8/block 09/17] btrfs: use bdev apis
Date: Thu, 4 Jan 2024 12:49:58 +0100 [thread overview]
Message-ID: <20240104114958.f3cit5q7syp3tn3a@quack3> (raw)
In-Reply-To: <ZYcZi5YYvt5QHrG9@casper.infradead.org>
On Sat 23-12-23 17:31:55, Matthew Wilcox wrote:
> On Thu, Dec 21, 2023 at 04:57:04PM +0800, Yu Kuai wrote:
> > @@ -3674,16 +3670,17 @@ struct btrfs_super_block *btrfs_read_dev_one_super(struct block_device *bdev,
> > * Drop the page of the primary superblock, so later read will
> > * always read from the device.
> > */
> > - invalidate_inode_pages2_range(mapping,
> > - bytenr >> PAGE_SHIFT,
> > + invalidate_bdev_range(bdev, bytenr >> PAGE_SHIFT,
> > (bytenr + BTRFS_SUPER_INFO_SIZE) >> PAGE_SHIFT);
> > }
> >
> > - page = read_cache_page_gfp(mapping, bytenr >> PAGE_SHIFT, GFP_NOFS);
> > - if (IS_ERR(page))
> > - return ERR_CAST(page);
> > + nofs_flag = memalloc_nofs_save();
> > + folio = bdev_read_folio(bdev, bytenr);
> > + memalloc_nofs_restore(nofs_flag);
>
> This is the wrong way to use memalloc_nofs_save/restore. They should be
> used at the point that the filesystem takes/releases whatever lock is
> also used during reclaim. I don't know btrfs well enough to suggest
> what lock is missing these annotations.
In principle I agree with you but in this particular case I agree the ask
is just too big. I suspect it is one of btrfs btree locks or maybe
chunk_mutex but I doubt even btrfs developers know and maybe it is just a
cargo cult. And it is not like this would be the first occurence of this
anti-pattern in btrfs - see e.g. device_list_add(), add_missing_dev(),
btrfs_destroy_delalloc_inodes() (here the wrapping around
invalidate_inode_pages2() looks really weird), and many others...
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2024-01-04 11:50 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-21 8:56 [PATCH RFC v3 for-6.8/block 00/17] block: don't access bd_inode directly from other modules Yu Kuai
2023-12-21 8:56 ` [PATCH RFC v3 for-6.8/block 01/17] block: add some bdev apis Yu Kuai
2023-12-21 8:56 ` [PATCH RFC v3 for-6.8/block 02/17] xen/blkback: use bdev api in xen_update_blkif_status() Yu Kuai
2024-01-04 11:06 ` Jan Kara
2024-01-04 12:19 ` Yu Kuai
2024-01-04 15:16 ` Jan Kara
2024-01-05 6:08 ` Christoph Hellwig
2023-12-21 8:56 ` [PATCH RFC v3 for-6.8/block 03/17] bcache: use bdev api in read_super() Yu Kuai
2023-12-21 8:56 ` [PATCH RFC v3 for-6.8/block 04/17] mtd: block2mtd: use bdev apis Yu Kuai
2024-01-04 11:28 ` Jan Kara
2024-01-04 12:22 ` Yu Kuai
2024-01-05 6:10 ` Christoph Hellwig
2024-01-05 10:31 ` Yu Kuai
2023-12-21 8:57 ` [PATCH RFC v3 for-6.8/block 05/17] s390/dasd: use bdev api in dasd_format() Yu Kuai
2023-12-21 8:57 ` [PATCH RFC v3 for-6.8/block 06/17] scsicam: use bdev api in scsi_bios_ptable() Yu Kuai
2023-12-21 8:57 ` [PATCH RFC v3 for-6.8/block 07/17] bcachefs: remove dead function bdev_sectors() Yu Kuai
2024-04-11 17:49 ` Kent Overstreet
2023-12-21 8:57 ` [PATCH RFC v3 for-6.8/block 08/17] bio: export bio_add_folio_nofail() Yu Kuai
2023-12-21 8:57 ` [PATCH RFC v3 for-6.8/block 09/17] btrfs: use bdev apis Yu Kuai
2023-12-23 17:31 ` Matthew Wilcox
2023-12-23 18:39 ` Kent Overstreet
2024-01-04 11:49 ` Jan Kara [this message]
2024-04-10 17:28 ` David Sterba
2023-12-21 8:57 ` [PATCH RFC v3 for-6.8/block 10/17] cramfs: use bdev apis in cramfs_blkdev_read() Yu Kuai
2023-12-21 8:58 ` [PATCH RFC v3 for-6.8/block 11/17] erofs: use bdev api Yu Kuai
2024-01-04 12:02 ` Jan Kara
2024-01-04 12:32 ` Yu Kuai
2024-01-05 4:43 ` Gao Xiang
2023-12-21 8:58 ` [PATCH RFC v3 for-6.8/block 12/17] nilfs2: use bdev api in nilfs_attach_log_writer() Yu Kuai
2023-12-21 14:54 ` Ryusuke Konishi
2023-12-21 8:58 ` [PATCH RFC v3 for-6.8/block 13/17] jbd2: use bdev apis Yu Kuai
2024-01-04 12:11 ` Jan Kara
2023-12-21 8:58 ` [PATCH RFC v3 for-6.8/block 14/17] buffer: add a new helper to read sb block Yu Kuai
2024-01-04 12:22 ` Jan Kara
2023-12-21 8:58 ` [PATCH RFC v3 for-6.8/block 15/17] ext4: use " Yu Kuai
2023-12-21 8:59 ` [PATCH RFC v3 for-6.8/block 16/17] ext4: remove block_device_ejected() Yu Kuai
2023-12-21 8:59 ` [PATCH RFC v3 for-6.8/block 17/17] ext4: use bdev apis Yu Kuai
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