[PATCH] mm: hugepage accounting fix

[sfrench/cifs-2.6.git] / fs / bio.c

diff --git a/fs/bio.c b/fs/bio.c
index 460554b07ff91501739ae7b2f21ea14392ea5e51..1f3bb501c262bc9b94ad9e0b73c5af8acc511c90 100644 (file)
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -123,9 +123,10 @@ static void bio_fs_destructor(struct bio *bio)
        bio_free(bio, fs_bio_set);
 }
 
-inline void bio_init(struct bio *bio)
+void bio_init(struct bio *bio)
 {
        bio->bi_next = NULL;
+       bio->bi_bdev = NULL;
        bio->bi_flags = 1 << BIO_UPTODATE;
        bio->bi_rw = 0;
        bio->bi_vcnt = 0;
@@ -252,7 +253,7 @@ inline int bio_hw_segments(request_queue_t *q, struct bio *bio)
  *     the actual data it points to. Reference count of returned
  *     bio will be one.
  */
-inline void __bio_clone(struct bio *bio, struct bio *bio_src)
+void __bio_clone(struct bio *bio, struct bio *bio_src)
 {
        request_queue_t *q = bdev_get_queue(bio_src->bi_bdev);
 
@@ -313,7 +314,8 @@ int bio_get_nr_vecs(struct block_device *bdev)
 }
 
 static int __bio_add_page(request_queue_t *q, struct bio *bio, struct page
-                         *page, unsigned int len, unsigned int offset)
+                         *page, unsigned int len, unsigned int offset,
+                         unsigned short max_sectors)
 {
        int retried_segments = 0;
        struct bio_vec *bvec;
@@ -324,10 +326,31 @@ static int __bio_add_page(request_queue_t *q, struct bio *bio, struct page
        if (unlikely(bio_flagged(bio, BIO_CLONED)))
                return 0;
 
-       if (bio->bi_vcnt >= bio->bi_max_vecs)
+       if (((bio->bi_size + len) >> 9) > max_sectors)
                return 0;
 
-       if (((bio->bi_size + len) >> 9) > q->max_sectors)
+       /*
+        * For filesystems with a blocksize smaller than the pagesize
+        * we will often be called with the same page as last time and
+        * a consecutive offset.  Optimize this special case.
+        */
+       if (bio->bi_vcnt > 0) {
+               struct bio_vec *prev = &bio->bi_io_vec[bio->bi_vcnt - 1];
+
+               if (page == prev->bv_page &&
+                   offset == prev->bv_offset + prev->bv_len) {
+                       prev->bv_len += len;
+                       if (q->merge_bvec_fn &&
+                           q->merge_bvec_fn(q, bio, prev) < len) {
+                               prev->bv_len -= len;
+                               return 0;
+                       }
+
+                       goto done;
+               }
+       }
+
+       if (bio->bi_vcnt >= bio->bi_max_vecs)
                return 0;
 
        /*
@@ -381,10 +404,31 @@ static int __bio_add_page(request_queue_t *q, struct bio *bio, struct page
        bio->bi_vcnt++;
        bio->bi_phys_segments++;
        bio->bi_hw_segments++;
+ done:
        bio->bi_size += len;
        return len;
 }
 
+/**
+ *     bio_add_pc_page -       attempt to add page to bio
+ *     @q: the target queue
+ *     @bio: destination bio
+ *     @page: page to add
+ *     @len: vec entry length
+ *     @offset: vec entry offset
+ *
+ *     Attempt to add a page to the bio_vec maplist. This can fail for a
+ *     number of reasons, such as the bio being full or target block
+ *     device limitations. The target block device must allow bio's
+ *      smaller than PAGE_SIZE, so it is always possible to add a single
+ *      page to an empty bio. This should only be used by REQ_PC bios.
+ */
+int bio_add_pc_page(request_queue_t *q, struct bio *bio, struct page *page,
+                   unsigned int len, unsigned int offset)
+{
+       return __bio_add_page(q, bio, page, len, offset, q->max_hw_sectors);
+}
+
 /**
  *     bio_add_page    -       attempt to add page to bio
  *     @bio: destination bio
@@ -401,8 +445,8 @@ static int __bio_add_page(request_queue_t *q, struct bio *bio, struct page
 int bio_add_page(struct bio *bio, struct page *page, unsigned int len,
                 unsigned int offset)
 {
-       return __bio_add_page(bdev_get_queue(bio->bi_bdev), bio, page,
-                             len, offset);
+       struct request_queue *q = bdev_get_queue(bio->bi_bdev);
+       return __bio_add_page(q, bio, page, len, offset, q->max_sectors);
 }
 
 struct bio_map_data {
@@ -514,7 +558,7 @@ struct bio *bio_copy_user(request_queue_t *q, unsigned long uaddr,
                        break;
                }
 
-               if (__bio_add_page(q, bio, page, bytes, 0) < bytes) {
+               if (bio_add_pc_page(q, bio, page, bytes, 0) < bytes) {
                        ret = -EINVAL;
                        break;
                }
@@ -628,7 +672,8 @@ static struct bio *__bio_map_user_iov(request_queue_t *q,
                        /*
                         * sorry...
                         */
-                       if (__bio_add_page(q, bio, pages[j], bytes, offset) < bytes)
+                       if (bio_add_pc_page(q, bio, pages[j], bytes, offset) <
+                                           bytes)
                                break;
 
                        len -= bytes;
@@ -801,8 +846,8 @@ static struct bio *__bio_map_kern(request_queue_t *q, void *data,
                if (bytes > len)
                        bytes = len;
 
-               if (__bio_add_page(q, bio, virt_to_page(data), bytes,
-                                  offset) < bytes)
+               if (bio_add_pc_page(q, bio, virt_to_page(data), bytes,
+                                   offset) < bytes)
                        break;
 
                data += bytes;
@@ -1228,6 +1273,7 @@ EXPORT_SYMBOL(bio_clone);
 EXPORT_SYMBOL(bio_phys_segments);
 EXPORT_SYMBOL(bio_hw_segments);
 EXPORT_SYMBOL(bio_add_page);
+EXPORT_SYMBOL(bio_add_pc_page);
 EXPORT_SYMBOL(bio_get_nr_vecs);
 EXPORT_SYMBOL(bio_map_user);
 EXPORT_SYMBOL(bio_unmap_user);