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Re: [PATCH 4/6] xfs: take i_mmap_lock on extent manipulation operations

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: [PATCH 4/6] xfs: take i_mmap_lock on extent manipulation operations
From: Brian Foster <bfoster@xxxxxxxxxx>
Date: Mon, 9 Feb 2015 15:31:36 -0500
Cc: xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1423083859-28439-5-git-send-email-david@xxxxxxxxxxxxx>
References: <1423083859-28439-1-git-send-email-david@xxxxxxxxxxxxx> <1423083859-28439-5-git-send-email-david@xxxxxxxxxxxxx>
User-agent: Mutt/1.5.23 (2014-03-12)
On Thu, Feb 05, 2015 at 08:04:17AM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
> 
> Now we have the i_mmap_lock being held across the page fault IO
> path, we now add extent manipulation operation exclusion by adding
> the lock to the paths that directly modify extent maps. This
> includes truncate, hole punching and other fallocate based
> operations. The operations will now take both the i_iolock and the
> i_mmaplock in exclusive mode, thereby ensuring that all IO and page
> faults block without holding any page locks while the extent
> manipulation is in progress.
> 
> This gives us the lock order during truncate of i_iolock ->
> i_mmaplock -> page_lock -> i_lock, hence providing the same
> lock order as the iolock provides the normal IO path without
> involving the mmap_sem.
> 
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> ---

Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>

>  fs/xfs/xfs_file.c  | 4 ++--
>  fs/xfs/xfs_ioctl.c | 4 ++--
>  fs/xfs/xfs_iops.c  | 5 +++--
>  3 files changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 2bb25fd..76bf14a 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -830,7 +830,7 @@ xfs_file_fallocate(
>                    FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE))
>               return -EOPNOTSUPP;
>  
> -     xfs_ilock(ip, XFS_IOLOCK_EXCL);
> +     xfs_ilock(ip, XFS_IOLOCK_EXCL|XFS_MMAPLOCK_EXCL);
>       if (mode & FALLOC_FL_PUNCH_HOLE) {
>               error = xfs_free_file_space(ip, offset, len);
>               if (error)
> @@ -894,7 +894,7 @@ xfs_file_fallocate(
>       }
>  
>  out_unlock:
> -     xfs_iunlock(ip, XFS_IOLOCK_EXCL);
> +     xfs_iunlock(ip, XFS_IOLOCK_EXCL|XFS_MMAPLOCK_EXCL);
>       return error;
>  }
>  
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index b88ab92..972fa13 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -636,7 +636,7 @@ xfs_ioc_space(
>       if (error)
>               return error;
>  
> -     xfs_ilock(ip, XFS_IOLOCK_EXCL);
> +     xfs_ilock(ip, XFS_IOLOCK_EXCL|XFS_MMAPLOCK_EXCL);
>  
>       switch (bf->l_whence) {
>       case 0: /*SEEK_SET*/
> @@ -725,7 +725,7 @@ xfs_ioc_space(
>       error = xfs_update_prealloc_flags(ip, flags);
>  
>  out_unlock:
> -     xfs_iunlock(ip, XFS_IOLOCK_EXCL);
> +     xfs_iunlock(ip, XFS_IOLOCK_EXCL|XFS_MMAPLOCK_EXCL);
>       mnt_drop_write_file(filp);
>       return error;
>  }
> diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
> index 8be5bb5..0362b65 100644
> --- a/fs/xfs/xfs_iops.c
> +++ b/fs/xfs/xfs_iops.c
> @@ -769,6 +769,7 @@ xfs_setattr_size(
>               return error;
>  
>       ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
> +     ASSERT(xfs_isilocked(ip, XFS_MMAPLOCK_EXCL));
>       ASSERT(S_ISREG(ip->i_d.di_mode));
>       ASSERT((iattr->ia_valid & (ATTR_UID|ATTR_GID|ATTR_ATIME|ATTR_ATIME_SET|
>               ATTR_MTIME_SET|ATTR_KILL_PRIV|ATTR_TIMES_SET)) == 0);
> @@ -984,9 +985,9 @@ xfs_vn_setattr(
>       int                     error;
>  
>       if (iattr->ia_valid & ATTR_SIZE) {
> -             xfs_ilock(ip, XFS_IOLOCK_EXCL);
> +             xfs_ilock(ip, XFS_IOLOCK_EXCL|XFS_MMAPLOCK_EXCL);
>               error = xfs_setattr_size(ip, iattr);
> -             xfs_iunlock(ip, XFS_IOLOCK_EXCL);
> +             xfs_iunlock(ip, XFS_IOLOCK_EXCL|XFS_MMAPLOCK_EXCL);
>       } else {
>               error = xfs_setattr_nonsize(ip, iattr, 0);
>       }
> -- 
> 2.0.0
> 
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