| Message ID | 153367990333.37314.16218849614019392916.stgit@djiang5-desk3.ch.intel.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [1/2] ext4: Close race between direct IO and ext4_break_layouts() | expand |
On Tue 07-08-18 15:11:43, Dave Jiang wrote: > This patch is the duplicate of ross's fix for ext4 for xfs. > > If the refcount of a page is lowered between the time that it is returned > by dax_busy_page() and when the refcount is again checked in > xfs_break_layouts() => ___wait_var_event(), the waiting function > xfs_wait_dax_page() will never be called. This means that > xfs_break_layouts() will still have 'retry' set to false, so we'll stop > looping and never check the refcount of other pages in this inode. > > Instead, always continue looping as long as dax_layout_busy_page() gives us > a page which it found with an elevated refcount. > > Signed-off-by: Dave Jiang <dave.jiang@intel.com> The patch looks good to me. You can add: Reviewed-by: Jan Kara <jack@suse.cz> Just one minor nit below: > @@ -746,9 +744,10 @@ xfs_break_dax_layouts( > if (!page) > return 0; > > + *did_unlock = true; I think it would be more understandable to name the argument of xfs_break_dax_layouts() as 'retry' instead of 'did_unlock' as it's not about unlocking anymore. Honza
On 08/08/2018 01:53 AM, Jan Kara wrote: > On Tue 07-08-18 15:11:43, Dave Jiang wrote: >> This patch is the duplicate of ross's fix for ext4 for xfs. >> >> If the refcount of a page is lowered between the time that it is returned >> by dax_busy_page() and when the refcount is again checked in >> xfs_break_layouts() => ___wait_var_event(), the waiting function >> xfs_wait_dax_page() will never be called. This means that >> xfs_break_layouts() will still have 'retry' set to false, so we'll stop >> looping and never check the refcount of other pages in this inode. >> >> Instead, always continue looping as long as dax_layout_busy_page() gives us >> a page which it found with an elevated refcount. >> >> Signed-off-by: Dave Jiang <dave.jiang@intel.com> > > The patch looks good to me. You can add: > > Reviewed-by: Jan Kara <jack@suse.cz> > > Just one minor nit below: > >> @@ -746,9 +744,10 @@ xfs_break_dax_layouts( >> if (!page) >> return 0; >> >> + *did_unlock = true; > > I think it would be more understandable to name the argument of > xfs_break_dax_layouts() as 'retry' instead of 'did_unlock' as it's not > about unlocking anymore. Thanks for the review Jan! I will change. I was trying to decide between less code change vs more clear definition. :) > > Honza >
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index a3e7767a5715..666c93fe5284 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -721,12 +721,10 @@ xfs_file_write_iter( static void xfs_wait_dax_page( - struct inode *inode, - bool *did_unlock) + struct inode *inode) { struct xfs_inode *ip = XFS_I(inode); - *did_unlock = true; xfs_iunlock(ip, XFS_MMAPLOCK_EXCL); schedule(); xfs_ilock(ip, XFS_MMAPLOCK_EXCL); @@ -746,9 +744,10 @@ xfs_break_dax_layouts( if (!page) return 0; + *did_unlock = true; return ___wait_var_event(&page->_refcount, atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE, - 0, 0, xfs_wait_dax_page(inode, did_unlock)); + 0, 0, xfs_wait_dax_page(inode)); } int
This patch is the duplicate of ross's fix for ext4 for xfs. If the refcount of a page is lowered between the time that it is returned by dax_busy_page() and when the refcount is again checked in xfs_break_layouts() => ___wait_var_event(), the waiting function xfs_wait_dax_page() will never be called. This means that xfs_break_layouts() will still have 'retry' set to false, so we'll stop looping and never check the refcount of other pages in this inode. Instead, always continue looping as long as dax_layout_busy_page() gives us a page which it found with an elevated refcount. Signed-off-by: Dave Jiang <dave.jiang@intel.com> --- fs/xfs/xfs_file.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)