search for: xfs_break_dax_layouts

...alph Campbell wrote: > error = ___wait_var_event(&page->_refcount, > - atomic_read(&page->_refcount) == 1, > + dax_layout_is_idle_page(page), > TASK_INTERRUPTIBLE, 0, 0, > ext4_wait_dax_page(ei)); > +++ b/fs/xfs/xfs_file.c > @@ -750,7 +750,7 @@ xfs_break_dax_layouts( > > *retry = true; > return ___wait_var_event(&page->_refcount, > - atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE, > + dax_layout_is_idle_page(page), TASK_INTERRUPTIBLE, > 0, 0, xfs_wait_dax_page(inode)); > } I still think a litte helper...

On Mon, Sep 14, 2020 at 04:10:38PM -0700, Dan Williams wrote: > You also need to fix up ext4_break_layouts() and > xfs_break_dax_layouts() to expect ->_refcount is 0 instead of 1. This > also needs some fstests exposure. While we're at it, can we add a wait_fsdax_unref helper macro that hides the _refcount access from the file systems?

...gt;_refcount) == 1, + dax_layout_is_idle_page(page), TASK_INTERRUPTIBLE, 0, 0, ext4_wait_dax_page(ei)); } while (error == 0); diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index a29f78a663ca..29ab96541bc1 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -750,7 +750,7 @@ xfs_break_dax_layouts( *retry = true; return ___wait_var_event(&page->_refcount, - atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE, + dax_layout_is_idle_page(page), TASK_INTERRUPTIBLE, 0, 0, xfs_wait_dax_page(inode)); } diff --git a/include/linux/dax.h b/include/linux/dax.h index 43...

On 9/15/20 11:10 PM, Christoph Hellwig wrote: > On Mon, Sep 14, 2020 at 04:10:38PM -0700, Dan Williams wrote: >> You also need to fix up ext4_break_layouts() and >> xfs_break_dax_layouts() to expect ->_refcount is 0 instead of 1. This >> also needs some fstests exposure. > > While we're at it, can we add a wait_fsdax_unref helper macro that hides > the _refcount access from the file systems? Sure. I'll add a separate patch for it in v2.

...TIBLE, 0, 0, - ext4_wait_dax_page(ei)); + error = dax_wait_page(ei, page, ext4_wait_dax_page); } while (error == 0); return error; diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 3d1b95124744..a5304aaeaa3a 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -749,9 +749,7 @@ xfs_break_dax_layouts( return 0; *retry = true; - return ___wait_var_event(&page->_refcount, - atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE, - 0, 0, xfs_wait_dax_page(inode)); + return dax_wait_page(inode, page, xfs_wait_dax_page); } int diff --git a/include/linux/dax.h b/include/l...

...TERRUPTIBLE, 0, 0, > ext4_wait_dax_page(ei)); > } while (error == 0); > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > index a29f78a663ca..29ab96541bc1 100644 > --- a/fs/xfs/xfs_file.c > +++ b/fs/xfs/xfs_file.c > @@ -750,7 +750,7 @@ xfs_break_dax_layouts( > > *retry = true; > return ___wait_var_event(&page->_refcount, > - atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE, > + dax_layout_is_idle_page(page), TASK_INTERRUPTIBLE, > 0...

...with refcount==0 were on an lru list. Since then, struct page has been reorganized to not collide the ->pgmap back pointer with the ->lru list and there have been other cleanups for page pinning that might make this incremental cleanup viable. You also need to fix up ext4_break_layouts() and xfs_break_dax_layouts() to expect ->_refcount is 0 instead of 1. This also needs some fstests exposure. > I have a modified THP migration patch series that applies on top of > this one and is cleaner since I don't have to add code to handle the > +1 reference count. The link below is for the earlier v2:...

Matthew Wilcox, Ira Weiny, and others have complained that ZONE_DEVICE struct page reference counting is ugly because they are "free" when the reference count is one instead of zero. This leads to explicit checks for ZONE_DEVICE pages in places like put_page(), GUP, THP splitting, and page migration which have to adjust the expected reference count when determining if the page is

ZONE_DEVICE struct pages have an extra reference count that complicates the code for put_page() and several places in the kernel that need to check the reference count to see that a page is not being used (gup, compaction, migration, etc.). Clean up the code so the reference count doesn't need to be treated specially for ZONE_DEVICE. Signed-off-by: Ralph Campbell <rcampbell at

...u list. Since > then, struct page has been reorganized to not collide the ->pgmap back > pointer with the ->lru list and there have been other cleanups for > page pinning that might make this incremental cleanup viable. > > You also need to fix up ext4_break_layouts() and > xfs_break_dax_layouts() to expect ->_refcount is 0 instead of 1. This > also needs some fstests exposure. Got it. Thanks! >> I have a modified THP migration patch series that applies on top of >> this one and is cleaner since I don't have to add code to handle the >> +1 reference count. The...

This is still an RFC because after looking at the pmem/dax code some more, I realized that the ZONE_DEVICE struct pages are being inserted into the process' page tables with vmf_insert_mixed() and a zero refcount on the ZONE_DEVICE struct page. This is sort of OK because insert_pfn() increments the reference count on the pgmap which is what prevents memunmap_pages() from freeing the struct