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@xxxxxx>
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@xxxxxxxx>
SUSE Labs, CR
