Re: [PATCH v7 12/14] xfs: prepare xfs_break_layouts() to be called with XFS_MMAPLOCK_EXCL

Darrick J. Wong
2018-03-30T15:17:35Z

On Wed, Mar 21, 2018 at 03:58:20PM -0700, Dan Williams wrote:
> In preparation for adding coordination between extent unmap operations
> and busy dax-pages, update xfs_break_layouts() to permit it to be called
> with the mmap lock held. This lock scheme will be required for
> coordinating the break of 'dax layouts' (non-idle dax (ZONE_DEVICE)
> pages mapped into the file's address space). Breaking dax layouts will
> be added to xfs_break_layouts() in a future patch, for now this preps
> the unmap call sites to take and hold XFS_MMAPLOCK_EXCL over the call to
> xfs_break_layouts().
>
> Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
> Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
> Cc: Dave Chinner <david@fromorbit.com>
> Suggested-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
> fs/xfs/xfs_file.c | 5 +----
> fs/xfs/xfs_ioctl.c | 5 +----
> fs/xfs/xfs_iops.c | 10 +++++++---
> fs/xfs/xfs_pnfs.c | 3 ++-
> 4 files changed, 11 insertions(+), 12 deletions(-)
>
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 9ea08326f876..18edf04811d0 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -768,7 +768,7 @@ xfs_file_fallocate(
> struct xfs_inode *ip = XFS_I(inode);
> long error;
> enum xfs_prealloc_flags flags = 0;
> - uint iolock = XFS_IOLOCK_EXCL;
> + uint iolock = XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL;
> loff_t new_size = 0;
> bool do_file_insert = false;
>
> @@ -782,9 +782,6 @@ xfs_file_fallocate(
> if (error)
> goto out_unlock;
>
> - xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
> - iolock |= XFS_MMAPLOCK_EXCL;
> -
> if (mode & FALLOC_FL_PUNCH_HOLE) {
> error = xfs_free_file_space(ip, offset, len);
> if (error)
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index 89fb1eb80aae..4151fade4bb1 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -614,7 +614,7 @@ xfs_ioc_space(
> struct xfs_inode *ip = XFS_I(inode);
> struct iattr iattr;
> enum xfs_prealloc_flags flags = 0;
> - uint iolock = XFS_IOLOCK_EXCL;
> + uint iolock = XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL;
> int error;
>
> /*
> @@ -648,9 +648,6 @@ xfs_ioc_space(
> if (error)
> goto out_unlock;
>
> - xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
> - iolock |= XFS_MMAPLOCK_EXCL;
> -
> switch (bf->l_whence) {
> case 0: /*SEEK_SET*/
> break;
> diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
> index 951e84df5576..d23aa08426f9 100644
> --- a/fs/xfs/xfs_iops.c
> +++ b/fs/xfs/xfs_iops.c
> @@ -1028,13 +1028,17 @@ xfs_vn_setattr(
>
> if (iattr->ia_valid & ATTR_SIZE) {
> struct xfs_inode *ip = XFS_I(d_inode(dentry));
> - uint iolock = XFS_IOLOCK_EXCL;
> + uint iolock;
> +
> + xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
> + iolock = XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL;
>
> error = xfs_break_layouts(d_inode(dentry), &iolock);
> - if (error)
> + if (error) {
> + xfs_iunlock(ip, XFS_MMAPLOCK_EXCL);
> return error;
> + }
>
> - xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
> error = xfs_vn_setattr_size(dentry, iattr);
> xfs_iunlock(ip, XFS_MMAPLOCK_EXCL);
> } else {
> diff --git a/fs/xfs/xfs_pnfs.c b/fs/xfs/xfs_pnfs.c
> index aa6c5c193f45..6ea7b0b55d02 100644
> --- a/fs/xfs/xfs_pnfs.c
> +++ b/fs/xfs/xfs_pnfs.c
> @@ -43,7 +43,8 @@ xfs_break_layouts(
> while ((error = break_layout(inode, false) == -EWOULDBLOCK)) {
> xfs_iunlock(ip, *iolock);
> error = break_layout(inode, true);
> - *iolock = XFS_IOLOCK_EXCL;
> + *iolock &= ~XFS_IOLOCK_SHARED;
> + *iolock |= XFS_IOLOCK_EXCL;
> xfs_ilock(ip, *iolock);
> }
>
>
> --
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