Re: [PATCH 2/2] ext4: Fix mmap data corruption when blocksize < pagesize

Re: [PATCH 2/2] ext4: Fix mmap data corruption when blocksize < pagesize

[Jan Kara]

On Tue 23-09-14 17:03:23, Jan Kara wrote:
> Use block_create_hole() when hole is being created in a file so that
> ->page_mkwrite() will get called for the partial tail page if it is
> mmaped (see the first patch in the series for details).
  Just out of curiosity I did a change similar to this one for ext4 to XFS
and indeed it fixed generic/030 test failures for XFS with blocksize 1k.

								Honza

PS: I forgot to CC xfs list in the original posting. You can find the VFS
    patch e.g. at http://www.spinics.net/lists/linux-mm/msg78976.html

> Signed-off-by: Jan Kara <jack@suse.cz>
> ---
>  fs/ext4/inode.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 3aa26e9117c4..fdcb007c2c9e 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -4536,8 +4536,12 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
>  				ext4_orphan_del(NULL, inode);
>  				goto err_out;
>  			}
> -		} else
> +		} else {
> +			loff_t old_size = inode->i_size;
> +
>  			i_size_write(inode, attr->ia_size);
> +			block_create_hole(inode, old_size, inode->i_size);
> +		}
>  
>  		/*
>  		 * Blocks are going to be removed from the inode. Wait
> -- 
> 1.8.1.4
> 
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs

Re: [PATCH 2/2] ext4: Fix mmap data corruption when blocksize < pagesize

[Jan Kara]

[-- Attachment #1: Type: text/plain, Size: 1624 bytes --]

On Wed 24-09-14 10:45:19, Jan Kara wrote:
> On Tue 23-09-14 17:03:23, Jan Kara wrote:
> > Use block_create_hole() when hole is being created in a file so that
> > ->page_mkwrite() will get called for the partial tail page if it is
> > mmaped (see the first patch in the series for details).
>   Just out of curiosity I did a change similar to this one for ext4 to XFS
> and indeed it fixed generic/030 test failures for XFS with blocksize 1k.
  Just for reference attached the patch I was testing - I can resend with
proper changelog etc. if people are fine with this approach.

								Honza

> > Signed-off-by: Jan Kara <jack@suse.cz>
> > ---
> >  fs/ext4/inode.c | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> > 
> > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> > index 3aa26e9117c4..fdcb007c2c9e 100644
> > --- a/fs/ext4/inode.c
> > +++ b/fs/ext4/inode.c
> > @@ -4536,8 +4536,12 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
> >  				ext4_orphan_del(NULL, inode);
> >  				goto err_out;
> >  			}
> > -		} else
> > +		} else {
> > +			loff_t old_size = inode->i_size;
> > +
> >  			i_size_write(inode, attr->ia_size);
> > +			block_create_hole(inode, old_size, inode->i_size);
> > +		}
> >  
> >  		/*
> >  		 * Blocks are going to be removed from the inode. Wait
> > -- 
> > 1.8.1.4
> > 
> -- 
> Jan Kara <jack@suse.cz>
> SUSE Labs, CR
> --
> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

[-- Attachment #2: 0001-xfs-Fix-mmap-data-corruption.patch --]
[-- Type: text/x-patch, Size: 738 bytes --]

>From ceedc36b1c99c25ebb55c88f6ab059347b52f4ec Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Wed, 24 Sep 2014 10:18:25 +0200
Subject: [PATCH] xfs: Fix mmap data corruption

Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/xfs/xfs_iops.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 72129493e9d3..19ce64bfb4f7 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -848,6 +848,8 @@ xfs_setattr_size(
 	if (error)
 		return error;
 	truncate_setsize(inode, newsize);
+	if (oldsize < newsize)
+		block_create_hole(inode, oldsize, newsize);
 
 	tp = xfs_trans_alloc(mp, XFS_TRANS_SETATTR_SIZE);
 	error = xfs_trans_reserve(tp, &M_RES(mp)->tr_itruncate, 0, 0);
-- 
1.8.1.4


[-- Attachment #3: Type: text/plain, Size: 121 bytes --]

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs

[PATCH 0/2 v2] Fix data corruption when blocksize < pagesize for mmapped data

[Jan Kara]

  Hello,

  this is a second version of the patches to fix data corruption in mmapped
data when blocksize < pagesize as tested by xfstests generic/030 test.
The patchset fixes XFS and ext4. I've checked and btrfs doesn't need fixing
because it doesn't support blocksize < pagesize. If that's ever going
to change btrfs will likely need a similar treatment. ocfs2, ext2, ext3 are
OK since they happily allocate blocks during writeback. For other filesystems
like gfs2, ubifs, nilfs, ceph,... I'm not sure whether they support blocksize <
pagesize at all. Interesting is also NFS which may care but I don't understand
its ->page_mkwrite() handler good enough to judge.

Changes since v1:
- changed helper function name and moved it to mm/truncate.c - I originally
  thought we can make the helper function update i_size to simplify the
  interface but it's actually impossible due to generic_write_end() lock
  ordering constraints.
- used round_up() instead of ALIGN()
- taught truncate_setsize() to use the helper function

								Honza

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs

[PATCH 2/2] ext4: Fix mmap data corruption when blocksize < pagesize

[Jan Kara]

Use truncate_isize_extended() when hole is being created in a file so that
->page_mkwrite() will get called for the partial tail page if it is
mmaped (see the first patch in the series for details).

Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/inode.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 3aa26e9117c4..9e269489e094 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4536,8 +4536,12 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
 				ext4_orphan_del(NULL, inode);
 				goto err_out;
 			}
-		} else
+		} else {
+			loff_t oldsize = inode->i_size;
+
 			i_size_write(inode, attr->ia_size);
+			pagecache_isize_extended(inode, oldsize, inode->i_size);
+		}
 
 		/*
 		 * Blocks are going to be removed from the inode. Wait
-- 
1.8.1.4

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs

Re: [PATCH 2/2] ext4: Fix mmap data corruption when blocksize < pagesize

[Theodore Ts'o]

On Thu, Sep 25, 2014 at 02:41:56PM +0200, Jan Kara wrote:
> Use truncate_isize_extended() when hole is being created in a file so that
> ->page_mkwrite() will get called for the partial tail page if it is
> mmaped (see the first patch in the series for details).
> 
> Signed-off-by: Jan Kara <jack@suse.cz>

Applied to the ext4 tree, thanks.

					- Ted

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs

[PATCH 0/2 v2] Fix data corruption when blocksize < pagesize for mmapped data

[Jan Kara]

  Hello,

  this is a second version of the patches to fix data corruption in mmapped
data when blocksize < pagesize as tested by xfstests generic/030 test.
The patchset fixes XFS and ext4. I've checked and btrfs doesn't need fixing
because it doesn't support blocksize < pagesize. If that's ever going
to change btrfs will likely need a similar treatment. ocfs2, ext2, ext3 are
OK since they happily allocate blocks during writeback. For other filesystems
like gfs2, ubifs, nilfs, ceph,... I'm not sure whether they support blocksize <
pagesize at all. Interesting is also NFS which may care but I don't understand
its ->page_mkwrite() handler good enough to judge.

Changes since v1:
- changed helper function name and moved it to mm/truncate.c - I originally
  thought we can make the helper function update i_size to simplify the
  interface but it's actually impossible due to generic_write_end() lock
  ordering constraints.
- used round_up() instead of ALIGN()
- taught truncate_setsize() to use the helper function

								Honza

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs

[PATCH 2/2] ext4: Fix mmap data corruption when blocksize < pagesize

[Jan Kara]

Use truncate_isize_extended() when hole is being created in a file so that
->page_mkwrite() will get called for the partial tail page if it is
mmaped (see the first patch in the series for details).

Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/inode.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 3aa26e9117c4..9e269489e094 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4536,8 +4536,12 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
 				ext4_orphan_del(NULL, inode);
 				goto err_out;
 			}
-		} else
+		} else {
+			loff_t oldsize = inode->i_size;
+
 			i_size_write(inode, attr->ia_size);
+			pagecache_isize_extended(inode, oldsize, inode->i_size);
+		}
 
 		/*
 		 * Blocks are going to be removed from the inode. Wait
-- 
1.8.1.4

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs