1 files changed, 90 insertions, 31 deletions

diff --git a/lib/flex_array.c b/lib/flex_array.c
index 7baed2fc3bc8..66eef2e4483e 100644
--- a/lib/flex_array.c
+++ b/lib/flex_array.c
@@ -28,23 +28,6 @@ struct flex_array_part {
         char elements[FLEX_ARRAY_PART_SIZE];
 };
 
-static inline int __elements_per_part(int element_size)
-{
-        return FLEX_ARRAY_PART_SIZE / element_size;
-}
-
-static inline int bytes_left_in_base(void)
-{
-        int element_offset = offsetof(struct flex_array, parts);
-        int bytes_left = FLEX_ARRAY_BASE_SIZE - element_offset;
-        return bytes_left;
-}
-
-static inline int nr_base_part_ptrs(void)
-{
-        return bytes_left_in_base() / sizeof(struct flex_array_part *);
-}
-
 /*
  * If a user requests an allocation which is small
  * enough, we may simply use the space in the
@@ -54,7 +37,7 @@ static inline int nr_base_part_ptrs(void)
 static inline int elements_fit_in_base(struct flex_array *fa)
 {
         int data_size = fa->element_size * fa->total_nr_elements;
-        if (data_size <= bytes_left_in_base())
+        if (data_size <= FLEX_ARRAY_BASE_BYTES_LEFT)
                 return 1;
         return 0;
 }
@@ -63,6 +46,7 @@ static inline int elements_fit_in_base(struct flex_array *fa)
  * flex_array_alloc - allocate a new flexible array
  * @element_size:       the size of individual elements in the array
  * @total:              total number of elements that this should hold
+ * @flags:              page allocation flags to use for base array
  *
  * Note: all locking must be provided by the caller.
  *
@@ -103,7 +87,8 @@ struct flex_array *flex_array_alloc(int element_size, unsigned int total,
                                         gfp_t flags)
 {
         struct flex_array *ret;
-        int max_size = nr_base_part_ptrs() * __elements_per_part(element_size);
+        int max_size = FLEX_ARRAY_NR_BASE_PTRS *
+                                FLEX_ARRAY_ELEMENTS_PER_PART(element_size);
 
         /* max_size will end up 0 if element_size > PAGE_SIZE */
         if (total > max_size)
@@ -113,17 +98,21 @@ struct flex_array *flex_array_alloc(int element_size, unsigned int total,
                 return NULL;
         ret->element_size = element_size;
         ret->total_nr_elements = total;
+        if (elements_fit_in_base(ret) && !(flags & __GFP_ZERO))
+                memset(ret->parts[0], FLEX_ARRAY_FREE,
+                                                FLEX_ARRAY_BASE_BYTES_LEFT);
         return ret;
 }
 
 static int fa_element_to_part_nr(struct flex_array *fa,
                                         unsigned int element_nr)
 {
-        return element_nr / __elements_per_part(fa->element_size);
+        return element_nr / FLEX_ARRAY_ELEMENTS_PER_PART(fa->element_size);
 }
 
 /**
  * flex_array_free_parts - just free the second-level pages
+ * @fa:         the flex array from which to free parts
  *
  * This is to be used in cases where the base 'struct flex_array'
  * has been statically allocated and should not be free.
@@ -131,11 +120,10 @@ static int fa_element_to_part_nr(struct flex_array *fa,
 void flex_array_free_parts(struct flex_array *fa)
 {
         int part_nr;
-        int max_part = nr_base_part_ptrs();
 
         if (elements_fit_in_base(fa))
                 return;
-        for (part_nr = 0; part_nr < max_part; part_nr++)
+        for (part_nr = 0; part_nr < FLEX_ARRAY_NR_BASE_PTRS; part_nr++)
                 kfree(fa->parts[part_nr]);
 }
 
@@ -150,7 +138,8 @@ static unsigned int index_inside_part(struct flex_array *fa,
 {
         unsigned int part_offset;
 
-        part_offset = element_nr % __elements_per_part(fa->element_size);
+        part_offset = element_nr %
+                                FLEX_ARRAY_ELEMENTS_PER_PART(fa->element_size);
         return part_offset * fa->element_size;
 }
 
@@ -159,15 +148,12 @@ __fa_get_part(struct flex_array *fa, int part_nr, gfp_t flags)
 {
         struct flex_array_part *part = fa->parts[part_nr];
         if (!part) {
-                /*
-                 * This leaves the part pages uninitialized
-                 * and with potentially random data, just
-                 * as if the user had kmalloc()'d the whole.
-                 * __GFP_ZERO can be used to zero it.
-                 */
-                part = kmalloc(FLEX_ARRAY_PART_SIZE, flags);
+                part = kmalloc(sizeof(struct flex_array_part), flags);
                 if (!part)
                         return NULL;
+                if (!(flags & __GFP_ZERO))
+                        memset(part, FLEX_ARRAY_FREE,
+                                sizeof(struct flex_array_part));
                 fa->parts[part_nr] = part;
         }
         return part;
@@ -175,9 +161,12 @@ __fa_get_part(struct flex_array *fa, int part_nr, gfp_t flags)
 
 /**
  * flex_array_put - copy data into the array at @element_nr
- * @src:        address of data to copy into the array
+ * @fa:         the flex array to copy data into
  * @element_nr: index of the position in which to insert
  *              the new element.
+ * @src:        address of data to copy into the array
+ * @flags:      page allocation flags to use for array expansion
+ *
  *
  * Note that this *copies* the contents of @src into
  * the array.  If you are trying to store an array of
@@ -207,9 +196,38 @@ int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src,
 }
 
 /**
+ * flex_array_clear - clear element in array at @element_nr
+ * @fa:         the flex array of the element.
+ * @element_nr: index of the position to clear.
+ *
+ * Locking must be provided by the caller.
+ */
+int flex_array_clear(struct flex_array *fa, unsigned int element_nr)
+{
+        int part_nr = fa_element_to_part_nr(fa, element_nr);
+        struct flex_array_part *part;
+        void *dst;
+
+        if (element_nr >= fa->total_nr_elements)
+                return -ENOSPC;
+        if (elements_fit_in_base(fa))
+                part = (struct flex_array_part *)&fa->parts[0];
+        else {
+                part = fa->parts[part_nr];
+                if (!part)
+                        return -EINVAL;
+        }
+        dst = &part->elements[index_inside_part(fa, element_nr)];
+        memset(dst, FLEX_ARRAY_FREE, fa->element_size);
+        return 0;
+}
+
+/**
  * flex_array_prealloc - guarantee that array space exists
+ * @fa:         the flex array for which to preallocate parts
  * @start:      index of first array element for which space is allocated
  * @end:        index of last (inclusive) element for which space is allocated
+ * @flags:      page allocation flags
  *
  * This will guarantee that no future calls to flex_array_put()
  * will allocate memory.  It can be used if you are expecting to
@@ -242,6 +260,7 @@ int flex_array_prealloc(struct flex_array *fa, unsigned int start,
 
 /**
  * flex_array_get - pull data back out of the array
+ * @fa:         the flex array from which to extract data
  * @element_nr: index of the element to fetch from the array
  *
  * Returns a pointer to the data at index @element_nr.  Note
@@ -266,3 +285,43 @@ void *flex_array_get(struct flex_array *fa, unsigned int element_nr)
         }
         return &part->elements[index_inside_part(fa, element_nr)];
 }
+
+static int part_is_free(struct flex_array_part *part)
+{
+        int i;
+
+        for (i = 0; i < sizeof(struct flex_array_part); i++)
+                if (part->elements[i] != FLEX_ARRAY_FREE)
+                        return 0;
+        return 1;
+}
+
+/**
+ * flex_array_shrink - free unused second-level pages
+ * @fa:         the flex array to shrink
+ *
+ * Frees all second-level pages that consist solely of unused
+ * elements.  Returns the number of pages freed.
+ *
+ * Locking must be provided by the caller.
+ */
+int flex_array_shrink(struct flex_array *fa)
+{
+        struct flex_array_part *part;
+        int part_nr;
+        int ret = 0;
+
+        if (elements_fit_in_base(fa))
+                return ret;
+        for (part_nr = 0; part_nr < FLEX_ARRAY_NR_BASE_PTRS; part_nr++) {
+                part = fa->parts[part_nr];
+                if (!part)
+                        continue;
+                if (part_is_free(part)) {
+                        fa->parts[part_nr] = NULL;
+                        kfree(part);
+                        ret++;
+                }
+        }
+        return ret;
+}