afs: Trace page dirty/clean

Add a trace event that logs the dirtying and cleaning of pages attached to
AFS inodes.

Signed-off-by: David Howells <dhowells@redhat.com>

3 files changed, 70 insertions, 13 deletions

diff --git a/fs/afs/file.c b/fs/afs/file.c
index 675c5c268a52..a39192ced99e 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -583,6 +583,9 @@ static int afs_readpages(struct file *file, struct address_space *mapping,
 static void afs_invalidatepage(struct page *page, unsigned int offset,
                                unsigned int length)
 {
+        struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
+        unsigned long priv;
+
         _enter("{%lu},%u,%u", page->index, offset, length);
 
         BUG_ON(!PageLocked(page));
@@ -598,6 +601,9 @@ static void afs_invalidatepage(struct page *page, unsigned int offset,
 #endif
 
                 if (PagePrivate(page)) {
+                        priv = page_private(page);
+                        trace_afs_page_dirty(vnode, tracepoint_string("inval"),
+                                             page->index, priv);
                         set_page_private(page, 0);
                         ClearPagePrivate(page);
                 }
@@ -613,6 +619,7 @@ static void afs_invalidatepage(struct page *page, unsigned int offset,
 static int afs_releasepage(struct page *page, gfp_t gfp_flags)
 {
         struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
+        unsigned long priv;
 
         _enter("{{%x:%u}[%lu],%lx},%x",
                vnode->fid.vid, vnode->fid.vnode, page->index, page->flags,
@@ -628,6 +635,9 @@ static int afs_releasepage(struct page *page, gfp_t gfp_flags)
 #endif
 
         if (PagePrivate(page)) {
+                priv = page_private(page);
+                trace_afs_page_dirty(vnode, tracepoint_string("rel"),
+                                     page->index, priv);
                 set_page_private(page, 0);
                 ClearPagePrivate(page);
         }
diff --git a/fs/afs/write.c b/fs/afs/write.c
index 6807277ef956..4472882f06df 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -18,19 +18,6 @@
 #include "internal.h"
 
 /*
- * We use page->private to hold the amount of the page that we've written to,
- * splitting the field into two parts.  However, we need to represent a range
- * 0...PAGE_SIZE inclusive, so we can't support 64K pages on a 32-bit system.
- */
-#if PAGE_SIZE > 32768
-#define AFS_PRIV_MAX    0xffffffff
-#define AFS_PRIV_SHIFT  32
-#else
-#define AFS_PRIV_MAX    0xffff
-#define AFS_PRIV_SHIFT  16
-#endif
-
-/*
  * mark a page as having been made dirty and thus needing writeback
  */
 int afs_set_page_dirty(struct page *page)
@@ -145,6 +132,8 @@ try_again:
 
         priv = (unsigned long)t << AFS_PRIV_SHIFT;
         priv |= f;
+        trace_afs_page_dirty(vnode, tracepoint_string("begin"),
+                             page->index, priv);
         SetPagePrivate(page);
         set_page_private(page, priv);
         _leave(" = 0");
@@ -386,6 +375,7 @@ static int afs_write_back_from_locked_page(struct address_space *mapping,
                                            struct page *primary_page,
                                            pgoff_t final_page)
 {
+        struct afs_vnode *vnode = AFS_FS_I(mapping->host);
         struct page *pages[8], *page;
         unsigned long count, priv;
         unsigned n, offset, to, f, t;
@@ -407,8 +397,13 @@ static int afs_write_back_from_locked_page(struct address_space *mapping,
         priv = page_private(primary_page);
         offset = priv & AFS_PRIV_MAX;
         to = priv >> AFS_PRIV_SHIFT;
+        trace_afs_page_dirty(vnode, tracepoint_string("store"),
+                             primary_page->index, priv);
 
         WARN_ON(offset == to);
+        if (offset == to)
+                trace_afs_page_dirty(vnode, tracepoint_string("WARN"),
+                                     primary_page->index, priv);
 
         if (start >= final_page || to < PAGE_SIZE)
                 goto no_more;
@@ -452,6 +447,9 @@ static int afs_write_back_from_locked_page(struct address_space *mapping,
                         }
                         to = t;
 
+                        trace_afs_page_dirty(vnode, tracepoint_string("store+"),
+                                             page->index, priv);
+
                         if (!clear_page_dirty_for_io(page))
                                 BUG();
                         if (test_set_page_writeback(page))
@@ -657,6 +655,7 @@ int afs_writepages(struct address_space *mapping,
 void afs_pages_written_back(struct afs_vnode *vnode, struct afs_call *call)
 {
         struct pagevec pv;
+        unsigned long priv;
         unsigned count, loop;
         pgoff_t first = call->first, last = call->last;
 
@@ -676,6 +675,9 @@ void afs_pages_written_back(struct afs_vnode *vnode, struct afs_call *call)
                 ASSERTCMP(pv.nr, ==, count);
 
                 for (loop = 0; loop < count; loop++) {
+                        priv = page_private(pv.pages[loop]);
+                        trace_afs_page_dirty(vnode, tracepoint_string("clear"),
+                                             pv.pages[loop]->index, priv);
                         set_page_private(pv.pages[loop], 0);
                         end_page_writeback(pv.pages[loop]);
                 }
@@ -783,6 +785,8 @@ int afs_page_mkwrite(struct vm_fault *vmf)
 
         priv = (unsigned long)PAGE_SIZE << AFS_PRIV_SHIFT; /* To */
         priv |= 0; /* From */
+        trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"),
+                             vmf->page->index, priv);
         SetPagePrivate(vmf->page);
         set_page_private(vmf->page, priv);
 
@@ -840,9 +844,13 @@ int afs_launder_page(struct page *page)
                         t = priv >> AFS_PRIV_SHIFT;
                 }
 
+                trace_afs_page_dirty(vnode, tracepoint_string("launder"),
+                                     page->index, priv);
                 ret = afs_store_data(mapping, page->index, page->index, t, f);
         }
 
+        trace_afs_page_dirty(vnode, tracepoint_string("laundered"),
+                             page->index, priv);
         set_page_private(page, 0);
         ClearPagePrivate(page);
 
diff --git a/include/trace/events/afs.h b/include/trace/events/afs.h
index 9cfb7657b72c..5f4e8193932d 100644
--- a/include/trace/events/afs.h
+++ b/include/trace/events/afs.h
@@ -402,6 +402,45 @@ TRACE_EVENT(afs_dir_check_failed,
                       __entry->vnode, __entry->off, __entry->i_size)
             );
 
+/*
+ * We use page->private to hold the amount of the page that we've written to,
+ * splitting the field into two parts.  However, we need to represent a range
+ * 0...PAGE_SIZE inclusive, so we can't support 64K pages on a 32-bit system.
+ */
+#if PAGE_SIZE > 32768
+#define AFS_PRIV_MAX    0xffffffff
+#define AFS_PRIV_SHIFT  32
+#else
+#define AFS_PRIV_MAX    0xffff
+#define AFS_PRIV_SHIFT  16
+#endif
+
+TRACE_EVENT(afs_page_dirty,
+            TP_PROTO(struct afs_vnode *vnode, const char *where,
+                     pgoff_t page, unsigned long priv),
+
+            TP_ARGS(vnode, where, page, priv),
+
+            TP_STRUCT__entry(
+                    __field(struct afs_vnode *,         vnode           )
+                    __field(const char *,               where           )
+                    __field(pgoff_t,                    page            )
+                    __field(unsigned long,              priv            )
+                             ),
+
+            TP_fast_assign(
+                    __entry->vnode = vnode;
+                    __entry->where = where;
+                    __entry->page = page;
+                    __entry->priv = priv;
+                           ),
+
+            TP_printk("vn=%p %lx %s %lu-%lu",
+                      __entry->vnode, __entry->page, __entry->where,
+                      __entry->priv & AFS_PRIV_MAX,
+                      __entry->priv >> AFS_PRIV_SHIFT)
+            );
+
 #endif /* _TRACE_AFS_H */
 
 /* This part must be outside protection */