On Tue, Aug 24, 2021 at 10:48:15PM -0500, Alex Sierra wrote: > From: Ralph Campbell <rcampbell@xxxxxxxxxx> > > There are several places where ZONE_DEVICE struct pages assume a reference > count == 1 means the page is idle and free. Instead of open coding this, > add a helper function to hide this detail. > > Signed-off-by: Ralph Campbell <rcampbell@xxxxxxxxxx> > Signed-off-by: Alex Sierra <alex.sierra@xxxxxxx> > Reviewed-by: Christoph Hellwig <hch@xxxxxx> Looks fine to me, Acked-by: Darrick J. Wong <djwong@xxxxxxxxxx> --D > --- > v3: > [AS]: rename dax_layout_is_idle_page func to dax_page_unused > > v4: > [AS]: This ref count functionality was missing on fuse/dax.c. > --- > fs/dax.c | 4 ++-- > fs/ext4/inode.c | 5 +---- > fs/fuse/dax.c | 4 +--- > fs/xfs/xfs_file.c | 4 +--- > include/linux/dax.h | 10 ++++++++++ > 5 files changed, 15 insertions(+), 12 deletions(-) > > diff --git a/fs/dax.c b/fs/dax.c > index 62352cbcf0f4..c387d09e3e5a 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -369,7 +369,7 @@ static void dax_disassociate_entry(void *entry, struct address_space *mapping, > for_each_mapped_pfn(entry, pfn) { > struct page *page = pfn_to_page(pfn); > > - WARN_ON_ONCE(trunc && page_ref_count(page) > 1); > + WARN_ON_ONCE(trunc && !dax_page_unused(page)); > WARN_ON_ONCE(page->mapping && page->mapping != mapping); > page->mapping = NULL; > page->index = 0; > @@ -383,7 +383,7 @@ static struct page *dax_busy_page(void *entry) > for_each_mapped_pfn(entry, pfn) { > struct page *page = pfn_to_page(pfn); > > - if (page_ref_count(page) > 1) > + if (!dax_page_unused(page)) > return page; > } > return NULL; > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index fe6045a46599..05ffe6875cb1 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -3971,10 +3971,7 @@ int ext4_break_layouts(struct inode *inode) > if (!page) > return 0; > > - error = ___wait_var_event(&page->_refcount, > - atomic_read(&page->_refcount) == 1, > - TASK_INTERRUPTIBLE, 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/fuse/dax.c b/fs/fuse/dax.c > index ff99ab2a3c43..2b1f190ba78a 100644 > --- a/fs/fuse/dax.c > +++ b/fs/fuse/dax.c > @@ -677,9 +677,7 @@ static int __fuse_dax_break_layouts(struct inode *inode, bool *retry, > return 0; > > *retry = true; > - return ___wait_var_event(&page->_refcount, > - atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE, > - 0, 0, fuse_wait_dax_page(inode)); > + return dax_wait_page(inode, page, fuse_wait_dax_page); > } > > /* dmap_end == 0 leads to unmapping of whole file */ > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > index 396ef36dcd0a..182057281086 100644 > --- a/fs/xfs/xfs_file.c > +++ b/fs/xfs/xfs_file.c > @@ -840,9 +840,7 @@ 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/linux/dax.h > index b52f084aa643..8b5da1d60dbc 100644 > --- a/include/linux/dax.h > +++ b/include/linux/dax.h > @@ -243,6 +243,16 @@ static inline bool dax_mapping(struct address_space *mapping) > return mapping->host && IS_DAX(mapping->host); > } > > +static inline bool dax_page_unused(struct page *page) > +{ > + return page_ref_count(page) == 1; > +} > + > +#define dax_wait_page(_inode, _page, _wait_cb) \ > + ___wait_var_event(&(_page)->_refcount, \ > + dax_page_unused(_page), \ > + TASK_INTERRUPTIBLE, 0, 0, _wait_cb(_inode)) > + > #ifdef CONFIG_DEV_DAX_HMEM_DEVICES > void hmem_register_device(int target_nid, struct resource *r); > #else > -- > 2.32.0 >