From: Jan Kara <jack@suse.cz>
To: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>, Mike Snitzer <snitzer@redhat.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Richard Weinberger <richard@nod.at>,
Josef Bacik <josef@toxicpanda.com>, Coly Li <colyli@suse.de>,
linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
dm-devel@redhat.com, linux-mtd@lists.infradead.org,
Al Viro <viro@zeniv.linux.org.uk>, Jan Kara <jack@suse.com>,
Tejun Heo <tj@kernel.org>,
xen-devel@lists.xenproject.org, linux-bcache@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [dm-devel] [PATCH 18/20] fs: remove get_super_thawed and get_super_exclusive_thawed
Date: Thu, 19 Nov 2020 15:59:56 +0100 [thread overview]
Message-ID: <20201119145956.GA1981@quack2.suse.cz> (raw)
In-Reply-To: <20201118084800.2339180-19-hch@lst.de>
On Wed 18-11-20 09:47:58, Christoph Hellwig wrote:
> Just open code the wait in the only caller of both functions.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
As far as I remember, Al (added to CC) generally objected against exporting
bits from fs/super.c (like put_super(), __get_super()) in the past. FWIW I
also find a dedicated function in fs/super.c somewhat cleaner than
opencoding in quota code but I can live with both...
Honza
> ---
> fs/internal.h | 2 ++
> fs/quota/quota.c | 31 +++++++++++++++++++++-------
> fs/super.c | 51 ++--------------------------------------------
> include/linux/fs.h | 4 +---
> 4 files changed, 29 insertions(+), 59 deletions(-)
>
> diff --git a/fs/internal.h b/fs/internal.h
> index a7cd0f64faa4ab..47be21dfeebef5 100644
> --- a/fs/internal.h
> +++ b/fs/internal.h
> @@ -114,7 +114,9 @@ extern struct file *alloc_empty_file_noaccount(int, const struct cred *);
> */
> extern int reconfigure_super(struct fs_context *);
> extern bool trylock_super(struct super_block *sb);
> +struct super_block *__get_super(struct block_device *bdev, bool excl);
> extern struct super_block *user_get_super(dev_t);
> +void put_super(struct super_block *sb);
> extern bool mount_capable(struct fs_context *);
>
> /*
> diff --git a/fs/quota/quota.c b/fs/quota/quota.c
> index 9af95c7a0bbe3c..f3d32b0d9008f2 100644
> --- a/fs/quota/quota.c
> +++ b/fs/quota/quota.c
> @@ -20,6 +20,7 @@
> #include <linux/writeback.h>
> #include <linux/nospec.h>
> #include "compat.h"
> +#include "../internal.h"
>
> static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
> qid_t id)
> @@ -868,6 +869,7 @@ static struct super_block *quotactl_block(const char __user *special, int cmd)
> struct block_device *bdev;
> struct super_block *sb;
> struct filename *tmp = getname(special);
> + bool excl = false, thawed = false;
>
> if (IS_ERR(tmp))
> return ERR_CAST(tmp);
> @@ -875,17 +877,32 @@ static struct super_block *quotactl_block(const char __user *special, int cmd)
> putname(tmp);
> if (IS_ERR(bdev))
> return ERR_CAST(bdev);
> - if (quotactl_cmd_onoff(cmd))
> - sb = get_super_exclusive_thawed(bdev);
> - else if (quotactl_cmd_write(cmd))
> - sb = get_super_thawed(bdev);
> - else
> - sb = get_super(bdev);
> +
> + if (quotactl_cmd_onoff(cmd)) {
> + excl = true;
> + thawed = true;
> + } else if (quotactl_cmd_write(cmd)) {
> + thawed = true;
> + }
> +
> +retry:
> + sb = __get_super(bdev, excl);
> + if (thawed && sb && sb->s_writers.frozen != SB_UNFROZEN) {
> + if (excl)
> + up_write(&sb->s_umount);
> + else
> + up_read(&sb->s_umount);
> + wait_event(sb->s_writers.wait_unfrozen,
> + sb->s_writers.frozen == SB_UNFROZEN);
> + put_super(sb);
> + goto retry;
> + }
> +
> bdput(bdev);
> if (!sb)
> return ERR_PTR(-ENODEV);
> -
> return sb;
> +
> #else
> return ERR_PTR(-ENODEV);
> #endif
> diff --git a/fs/super.c b/fs/super.c
> index 98bb0629ee108e..343e5c1e538d2a 100644
> --- a/fs/super.c
> +++ b/fs/super.c
> @@ -307,7 +307,7 @@ static void __put_super(struct super_block *s)
> * Drops a temporary reference, frees superblock if there's no
> * references left.
> */
> -static void put_super(struct super_block *sb)
> +void put_super(struct super_block *sb)
> {
> spin_lock(&sb_lock);
> __put_super(sb);
> @@ -740,7 +740,7 @@ void iterate_supers_type(struct file_system_type *type,
>
> EXPORT_SYMBOL(iterate_supers_type);
>
> -static struct super_block *__get_super(struct block_device *bdev, bool excl)
> +struct super_block *__get_super(struct block_device *bdev, bool excl)
> {
> struct super_block *sb;
>
> @@ -789,53 +789,6 @@ struct super_block *get_super(struct block_device *bdev)
> }
> EXPORT_SYMBOL(get_super);
>
> -static struct super_block *__get_super_thawed(struct block_device *bdev,
> - bool excl)
> -{
> - while (1) {
> - struct super_block *s = __get_super(bdev, excl);
> - if (!s || s->s_writers.frozen == SB_UNFROZEN)
> - return s;
> - if (!excl)
> - up_read(&s->s_umount);
> - else
> - up_write(&s->s_umount);
> - wait_event(s->s_writers.wait_unfrozen,
> - s->s_writers.frozen == SB_UNFROZEN);
> - put_super(s);
> - }
> -}
> -
> -/**
> - * get_super_thawed - get thawed superblock of a device
> - * @bdev: device to get the superblock for
> - *
> - * Scans the superblock list and finds the superblock of the file system
> - * mounted on the device. The superblock is returned once it is thawed
> - * (or immediately if it was not frozen). %NULL is returned if no match
> - * is found.
> - */
> -struct super_block *get_super_thawed(struct block_device *bdev)
> -{
> - return __get_super_thawed(bdev, false);
> -}
> -EXPORT_SYMBOL(get_super_thawed);
> -
> -/**
> - * get_super_exclusive_thawed - get thawed superblock of a device
> - * @bdev: device to get the superblock for
> - *
> - * Scans the superblock list and finds the superblock of the file system
> - * mounted on the device. The superblock is returned once it is thawed
> - * (or immediately if it was not frozen) and s_umount semaphore is held
> - * in exclusive mode. %NULL is returned if no match is found.
> - */
> -struct super_block *get_super_exclusive_thawed(struct block_device *bdev)
> -{
> - return __get_super_thawed(bdev, true);
> -}
> -EXPORT_SYMBOL(get_super_exclusive_thawed);
> -
> /**
> * get_active_super - get an active reference to the superblock of a device
> * @bdev: device to get the superblock for
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 8667d0cdc71e76..a61df0dd4f1989 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1409,7 +1409,7 @@ enum {
>
> struct sb_writers {
> int frozen; /* Is sb frozen? */
> - wait_queue_head_t wait_unfrozen; /* for get_super_thawed() */
> + wait_queue_head_t wait_unfrozen; /* wait for thaw */
> struct percpu_rw_semaphore rw_sem[SB_FREEZE_LEVELS];
> };
>
> @@ -3132,8 +3132,6 @@ extern struct file_system_type *get_filesystem(struct file_system_type *fs);
> extern void put_filesystem(struct file_system_type *fs);
> extern struct file_system_type *get_fs_type(const char *name);
> extern struct super_block *get_super(struct block_device *);
> -extern struct super_block *get_super_thawed(struct block_device *);
> -extern struct super_block *get_super_exclusive_thawed(struct block_device *bdev);
> extern struct super_block *get_active_super(struct block_device *bdev);
> extern void drop_super(struct super_block *sb);
> extern void drop_super_exclusive(struct super_block *sb);
> --
> 2.29.2
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
--
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next prev parent reply other threads:[~2020-11-19 15:00 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-18 8:47 [dm-devel] merge struct block_device and struct hd_struct Christoph Hellwig
2020-11-18 8:47 ` [dm-devel] [PATCH 01/20] blk-cgroup: fix a hd_struct leak in blkcg_fill_root_iostats Christoph Hellwig
2020-11-18 14:09 ` Jan Kara
2020-11-19 8:37 ` Johannes Thumshirn
2020-11-24 12:26 ` Tejun Heo
2020-11-18 8:47 ` [dm-devel] [PATCH 02/20] block: remove a duplicate __disk_get_part prototype Christoph Hellwig
2020-11-18 14:10 ` Jan Kara
2020-11-19 8:37 ` Johannes Thumshirn
2020-11-18 8:47 ` [dm-devel] [PATCH 03/20] block: add a bdev_kobj helper Christoph Hellwig
2020-11-18 14:18 ` Jan Kara
2020-11-19 8:37 ` Johannes Thumshirn
2020-11-18 8:47 ` [dm-devel] [PATCH 04/20] block: use disk_part_iter_exit in disk_part_iter_next Christoph Hellwig
2020-11-18 14:19 ` Jan Kara
2020-11-19 8:37 ` Johannes Thumshirn
2020-11-18 8:47 ` [dm-devel] [PATCH 05/20] block: use put_device in put_disk Christoph Hellwig
2020-11-18 14:20 ` Jan Kara
2020-11-19 8:38 ` Johannes Thumshirn
2020-11-18 8:47 ` [dm-devel] [PATCH 06/20] block: change the hash used for looking up block devices Christoph Hellwig
2020-11-18 14:22 ` Jan Kara
2020-11-18 8:47 ` [dm-devel] [PATCH 07/20] init: refactor name_to_dev_t Christoph Hellwig
2020-11-18 14:37 ` Jan Kara
2020-11-19 7:52 ` Christoph Hellwig
2020-11-19 8:25 ` Jan Kara
2020-11-20 8:49 ` Christoph Hellwig
2020-11-19 8:38 ` Johannes Thumshirn
2020-11-18 8:47 ` [dm-devel] [PATCH 08/20] init: refactor devt_from_partuuid Christoph Hellwig
2020-11-18 14:41 ` Jan Kara
2020-11-18 8:47 ` [dm-devel] [PATCH 09/20] init: cleanup match_dev_by_uuid and match_dev_by_label Christoph Hellwig
2020-11-18 14:42 ` Jan Kara
2020-11-19 8:38 ` Johannes Thumshirn
2020-11-18 8:47 ` [dm-devel] [PATCH 10/20] block: refactor __blkdev_put Christoph Hellwig
2020-11-18 14:46 ` Jan Kara
2020-11-18 8:47 ` [dm-devel] [PATCH 11/20] block: reference struct block_device from struct hd_struct Christoph Hellwig
2020-11-19 9:41 ` Jan Kara
2020-11-20 8:56 ` Christoph Hellwig
2020-11-24 16:59 ` Tejun Heo
2020-11-25 11:40 ` Jan Kara
2020-11-25 12:09 ` Tejun Heo
2020-11-18 8:47 ` [dm-devel] [PATCH 12/20] block: simplify the block device claiming interface Christoph Hellwig
2020-11-19 10:07 ` Jan Kara
2020-11-18 8:47 ` [dm-devel] [PATCH 13/20] block: remove ->bd_contains Christoph Hellwig
2020-11-19 10:32 ` Jan Kara
2020-11-20 9:01 ` Christoph Hellwig
2020-11-18 8:47 ` [dm-devel] [PATCH 14/20] block: remove the nr_sects field in struct hd_struct Christoph Hellwig
2020-11-19 12:05 ` Jan Kara
2020-11-20 9:08 ` Christoph Hellwig
2020-11-20 11:21 ` Jan Kara
2020-11-20 15:32 ` Christoph Hellwig
2020-11-20 15:59 ` Matthew Wilcox
2020-11-20 16:01 ` Christoph Hellwig
2020-11-20 20:05 ` Jan Kara
2020-11-21 16:24 ` Christoph Hellwig
2020-11-18 8:47 ` [dm-devel] [PATCH 15/20] block: merge struct block_device and " Christoph Hellwig
2020-11-19 14:39 ` Jan Kara
2020-11-20 9:15 ` Christoph Hellwig
2020-11-20 10:53 ` Jan Kara
2020-11-18 8:47 ` [dm-devel] [PATCH 16/20] block: stop using bdget_disk for partition 0 Christoph Hellwig
2020-11-19 14:43 ` Jan Kara
2020-11-18 8:47 ` [dm-devel] [PATCH 17/20] filemap: consistently use ->f_mapping over ->i_mapping Christoph Hellwig
2020-11-19 14:53 ` Jan Kara
2020-11-19 15:13 ` Matthew Wilcox
2020-11-20 9:17 ` Christoph Hellwig
2020-11-18 8:47 ` [dm-devel] [PATCH 18/20] fs: remove get_super_thawed and get_super_exclusive_thawed Christoph Hellwig
2020-11-19 14:59 ` Jan Kara [this message]
2020-11-18 8:47 ` [dm-devel] [PATCH 19/20] bcache: remove a superflous lookup_bdev all Christoph Hellwig
2020-11-18 8:54 ` Coly Li
2020-11-18 9:10 ` Greg KH
2020-11-18 9:55 ` Coly Li
2020-11-18 16:24 ` Christoph Hellwig
2020-11-18 8:48 ` [dm-devel] [PATCH 20/20] block: remove i_bdev Christoph Hellwig
2020-11-18 8:56 ` [dm-devel] merge struct block_device and struct hd_struct Jan Beulich
2020-11-18 8:58 ` Christoph Hellwig
2020-11-18 9:04 ` Jan Beulich
2020-11-18 9:08 ` Christoph Hellwig
2020-11-18 9:09 ` Greg KH
2020-11-18 9:23 ` Jan Beulich
2020-11-18 9:32 ` Greg KH
2020-11-18 12:50 ` Matthew Wilcox
2020-11-18 9:13 ` Greg KH
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