On 8/15/23 10:57 AM, Amir Goldstein wrote:
> +/**
> + * kiocb_start_write - get write access to a superblock for async file io
> + * @iocb: the io context we want to submit the write with
> + *
> + * This is a variant of file_start_write() for async io submission.
> + * Should be matched with a call to kiocb_end_write().
> + */
> +static inline void kiocb_start_write(struct kiocb *iocb)
> +{
> + struct inode *inode = file_inode(iocb->ki_filp);
> +
> + iocb->ki_flags |= IOCB_WRITE;
> + if (WARN_ON_ONCE(iocb->ki_flags & IOCB_WRITE_STARTED))
> + return;
> + if (!S_ISREG(inode->i_mode))
> + return;
> + sb_start_write(inode->i_sb);
> + /*
> + * Fool lockdep by telling it the lock got released so that it
> + * doesn't complain about the held lock when we return to userspace.
> + */
> + __sb_writers_release(inode->i_sb, SB_FREEZE_WRITE);
> + iocb->ki_flags |= IOCB_WRITE_STARTED;
> +}
> +
> +/**
> + * kiocb_end_write - drop write access to a superblock after async file io
> + * @iocb: the io context we sumbitted the write with
> + *
> + * Should be matched with a call to kiocb_start_write().
> + */
> +static inline void kiocb_end_write(struct kiocb *iocb)
> +{
> + struct inode *inode = file_inode(iocb->ki_filp);
> +
> + if (!(iocb->ki_flags & IOCB_WRITE_STARTED))
> + return;
> + if (!S_ISREG(inode->i_mode))
> + return;
> + /*
> + * Tell lockdep we inherited freeze protection from submission thread.
> + */
> + __sb_writers_acquired(inode->i_sb, SB_FREEZE_WRITE);
> + sb_end_write(inode->i_sb);
> + iocb->ki_flags &= ~IOCB_WRITE_STARTED;
> }
Please don't add code that dips into the inode when it's not needed for
all callers.
--
Jens Axboe
