I don’t think I’m supposed to be on this thread – please move me to bcc! ☺ 

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caitlyn mason
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On 1/26/17, 9:28 AM, "David Sterba" <dste...@suse.cz> wrote:

    On Wed, Jan 25, 2017 at 07:06:18AM -0800, Liu Bo wrote:
    > On Wed, Jan 25, 2017 at 01:49:09PM +0530, Chandan Rajendra wrote:
    > > On Tuesday, January 24, 2017 03:58:51 PM Liu Bo wrote:
    > > > Commit "d0b7da88 Btrfs: btrfs_page_mkwrite: Reserve space in 
sectorsized units"
    > > > did this, but btrfs_lookup_ordered_range expects a 'length' rather 
than a
    > > > 'page_end'.
    > > > 
    > > > Signed-off-by: Liu Bo <bo.li....@oracle.com>
    > > > ---
    > > > Is this a candidate for stable?
    > > > 
    > > >  fs/btrfs/inode.c | 2 +-
    > > >  1 file changed, 1 insertion(+), 1 deletion(-)
    > > > 
    > > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
    > > > index 4e02426..366cf0b 100644
    > > > --- a/fs/btrfs/inode.c
    > > > +++ b/fs/btrfs/inode.c
    > > > @@ -9023,7 +9023,7 @@ int btrfs_page_mkwrite(struct vm_area_struct 
*vma, struct vm_fault *vmf)
    > > >        * we can't set the delalloc bits if there are pending ordered
    > > >        * extents.  Drop our locks and wait for them to finish
    > > >        */
    > > > -     ordered = btrfs_lookup_ordered_range(inode, page_start, 
page_end);
    > > > +     ordered = btrfs_lookup_ordered_range(inode, page_start, 
PAGE_SIZE);
    > > >       if (ordered) {
    > > >               unlock_extent_cached(io_tree, page_start, page_end,
    > > >                                    &cached_state, GFP_NOFS);
    > > > 
    > > 
    > > Thanks for fixing this,
    > > Reviewed-by: Chandan Rajendra <chan...@linux.vnet.ibm.com>
    > > 
    > > As for the question about whether this commit should be merged into the 
stable
    > > trees ... I am not sure about that since I don't notice any sort of 
filesystem
    > > corruption that can be caused by the current code i.e. With the 
existing code,
    > > apart from any ordered extents that map the page in question, we are 
most
    > > likely to be *unnecessarily* starting i/o on ordered extents that don't 
map
    > > the file offset range covered by the page. Chris, Josef or David, 
Please let
    > > us know your thoughts on this.
    > 
    > It could be a performance regression which causes fault writes have
    > unnecessary waits instead of a real corruption.
    
    Does not seem to be urgent for stable, but I'll consider it next time
    doing a stable round updates.
    

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