| Message ID | 20190301042448.6868-1-willy@infradead.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | dax: Flush partial PMDs correctly | expand |
On Thu 28-02-19 20:24:48, Matthew Wilcox wrote: > The radix tree would rewind the index in an iterator to the lowest index > of a multi-slot entry. The XArray iterators instead leave the index > unchanged, but I overlooked that when converting DAX from the radix tree > to the XArray. Adjust the index that we use for flushing to the start > of the PMD range. > > Fixes: c1901cd33cf4 "page cache: Convert find_get_entries_tag to XArray" > Reported-by: Piotr Balcer <piotr.balcer@intel.com> > Tested-by: Dan Williams <dan.j.williams@intel.com> > Signed-off-by: Matthew Wilcox <willy@infradead.org> > --- Thanks for the patch! One comment below: > @@ -894,17 +893,18 @@ static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev, > xas_unlock_irq(xas); > > /* > - * Even if dax_writeback_mapping_range() was given a wbc->range_start > - * in the middle of a PMD, the 'index' we are given will be aligned to > - * the start index of the PMD, as will the pfn we pull from 'entry'. > + * If dax_writeback_mapping_range() was given a wbc->range_start > + * in the middle of a PMD, the 'index' we are given needs to be > + * aligned to the start index of the PMD. > * This allows us to flush for PMD_SIZE and not have to worry about > * partial PMD writebacks. > */ > pfn = dax_to_pfn(entry); > - size = PAGE_SIZE << dax_entry_order(entry); > + count = 1UL << dax_entry_order(entry); > + index = xas->xa_index &~ (count - 1); Hum, why do you compute 'index' here when you actually never use it? The whole patch looks fishy since it is effectively a noop AFAICT... Honza > > dax_entry_mkclean(mapping, xas->xa_index, pfn); > - dax_flush(dax_dev, page_address(pfn_to_page(pfn)), size); > + dax_flush(dax_dev, page_address(pfn_to_page(pfn)), count * PAGE_SIZE); > /* > * After we have flushed the cache, we can clear the dirty tag. There > * cannot be new dirty data in the pfn after the flush has completed as > @@ -917,8 +917,7 @@ static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev, > xas_clear_mark(xas, PAGECACHE_TAG_DIRTY); > dax_wake_entry(xas, entry, false); > > - trace_dax_writeback_one(mapping->host, xas->xa_index, > - size >> PAGE_SHIFT); > + trace_dax_writeback_one(mapping->host, xas->xa_index, count); > return ret; > > put_unlocked: > -- > 2.20.1 >
On Fri, Mar 01, 2019 at 02:49:54PM +0100, Jan Kara wrote: > > pfn = dax_to_pfn(entry); > > - size = PAGE_SIZE << dax_entry_order(entry); > > + count = 1UL << dax_entry_order(entry); > > + index = xas->xa_index &~ (count - 1); > > Hum, why do you compute 'index' here when you actually never use it? The > whole patch looks fishy since it is effectively a noop AFAICT... *facepalm*. I lost the change to the next line while I was backing out some extraneous changes. > > dax_entry_mkclean(mapping, xas->xa_index, pfn); Replacement patch sent.
diff --git a/fs/dax.c b/fs/dax.c index 6959837cc465..f7a7af766efe 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -843,9 +843,8 @@ static void dax_entry_mkclean(struct address_space *mapping, pgoff_t index, static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev, struct address_space *mapping, void *entry) { - unsigned long pfn; + unsigned long pfn, index, count; long ret = 0; - size_t size; /* * A page got tagged dirty in DAX mapping? Something is seriously @@ -894,17 +893,18 @@ static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev, xas_unlock_irq(xas); /* - * Even if dax_writeback_mapping_range() was given a wbc->range_start - * in the middle of a PMD, the 'index' we are given will be aligned to - * the start index of the PMD, as will the pfn we pull from 'entry'. + * If dax_writeback_mapping_range() was given a wbc->range_start + * in the middle of a PMD, the 'index' we are given needs to be + * aligned to the start index of the PMD. * This allows us to flush for PMD_SIZE and not have to worry about * partial PMD writebacks. */ pfn = dax_to_pfn(entry); - size = PAGE_SIZE << dax_entry_order(entry); + count = 1UL << dax_entry_order(entry); + index = xas->xa_index &~ (count - 1); dax_entry_mkclean(mapping, xas->xa_index, pfn); - dax_flush(dax_dev, page_address(pfn_to_page(pfn)), size); + dax_flush(dax_dev, page_address(pfn_to_page(pfn)), count * PAGE_SIZE); /* * After we have flushed the cache, we can clear the dirty tag. There * cannot be new dirty data in the pfn after the flush has completed as @@ -917,8 +917,7 @@ static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev, xas_clear_mark(xas, PAGECACHE_TAG_DIRTY); dax_wake_entry(xas, entry, false); - trace_dax_writeback_one(mapping->host, xas->xa_index, - size >> PAGE_SHIFT); + trace_dax_writeback_one(mapping->host, xas->xa_index, count); return ret; put_unlocked: