Page cache miss tracing using ftrace on mm/filemap

[firefly-linux-kernel-4.4.55.git] / mm / filemap.c

diff --git a/mm/filemap.c b/mm/filemap.c
index 7905fe721aa8ab3db06c957c9f2cc63cea1fee5f..fa1f12a3589648f36a4aa541de4e19a57495a894 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -683,6 +683,47 @@ int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
        }
 }
 
+/**
+ * page_cache_next_hole - find the next hole (not-present entry)
+ * @mapping: mapping
+ * @index: index
+ * @max_scan: maximum range to search
+ *
+ * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the
+ * lowest indexed hole.
+ *
+ * Returns: the index of the hole if found, otherwise returns an index
+ * outside of the set specified (in which case 'return - index >=
+ * max_scan' will be true). In rare cases of index wrap-around, 0 will
+ * be returned.
+ *
+ * page_cache_next_hole may be called under rcu_read_lock. However,
+ * like radix_tree_gang_lookup, this will not atomically search a
+ * snapshot of the tree at a single point in time. For example, if a
+ * hole is created at index 5, then subsequently a hole is created at
+ * index 10, page_cache_next_hole covering both indexes may return 10
+ * if called under rcu_read_lock.
+ */
+pgoff_t page_cache_next_hole(struct address_space *mapping,
+                             pgoff_t index, unsigned long max_scan)
+{
+        unsigned long i;
+
+        for (i = 0; i < max_scan; i++) {
+                struct page *page;
+
+                page = radix_tree_lookup(&mapping->page_tree, index);
+                if (!page || radix_tree_exceptional_entry(page))
+                        break;
+                index++;
+                if (index == 0)
+                        break;
+        }
+
+        return index;
+}
+EXPORT_SYMBOL(page_cache_next_hole);
+
 /**
  * find_get_page - find and get a page reference
  * @mapping: the address_space to search
@@ -1109,6 +1150,8 @@ static void do_generic_file_read(struct file *filp, loff_t *ppos,
        unsigned int prev_offset;
        int error;
 
+       trace_mm_filemap_do_generic_file_read(filp, *ppos, desc->count, 1);
+
        index = *ppos >> PAGE_CACHE_SHIFT;
        prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT;
        prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1);
@@ -1503,7 +1546,7 @@ EXPORT_SYMBOL(generic_file_aio_read);
 static int page_cache_read(struct file *file, pgoff_t offset)
 {
        struct address_space *mapping = file->f_mapping;
-       struct page *page; 
+       struct page *page;
        int ret;
 
        do {
@@ -1520,7 +1563,7 @@ static int page_cache_read(struct file *file, pgoff_t offset)
                page_cache_release(page);
 
        } while (ret == AOP_TRUNCATED_PAGE);
-               
+
        return ret;
 }
 
@@ -2307,6 +2350,8 @@ static ssize_t generic_perform_write(struct file *file,
        ssize_t written = 0;
        unsigned int flags = 0;
 
+       trace_mm_filemap_generic_perform_write(file, pos, iov_iter_count(i), 0);
+
        /*
         * Copies from kernel address space cannot fail (NFSD is a big user).
         */
@@ -2405,7 +2450,7 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
                written += status;
                *ppos = pos + status;
        }
-       
+
        return written ? written : status;
 }
 EXPORT_SYMBOL(generic_file_buffered_write);