md/bitmap: store bytes in file rather than just in last page.

This number is more generally useful, and bytes-in-last-page is
easily extracted from it.

Signed-off-by: NeilBrown <neilb@suse.de>

2 files changed, 10 insertions, 8 deletions

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index c98f2fee1bd0..7a3be0d4103e 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -203,9 +203,13 @@ static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)
 
                 bdev = (rdev->meta_bdev) ? rdev->meta_bdev : rdev->bdev;
 
-                if (page->index == store->file_pages-1)
-                        size = roundup(store->last_page_size,
+                if (page->index == store->file_pages-1) {
+                        int last_page_size = store->bytes & (PAGE_SIZE-1);
+                        if (last_page_size == 0)
+                                last_page_size = PAGE_SIZE;
+                        size = roundup(last_page_size,
                                        bdev_logical_block_size(bdev));
+                }
                 /* Just make sure we aren't corrupting data or
                  * metadata
                  */
@@ -973,6 +977,8 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
         if (!bitmap->mddev->bitmap_info.external)
                 bytes += sizeof(bitmap_super_t);
 
+        store->bytes = bytes;
+
         num_pages = DIV_ROUND_UP(bytes, PAGE_SIZE);
 
         if (file && i_size_read(file->f_mapping->host) < bytes) {
@@ -1042,8 +1048,6 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
 
                         oldindex = index;
 
-                        store->last_page_size = count;
-
                         if (outofdate) {
                                 /*
                                  * if bitmap is out of date, dirty the
@@ -1965,9 +1969,7 @@ space_store(struct mddev *mddev, const char *buf, size_t len)
                 return -EINVAL;
 
         if (mddev->bitmap &&
-            sectors  < ((mddev->bitmap->storage.file_pages - 1)
-                              * PAGE_SIZE
-                        + mddev->bitmap->storage.last_page_size + 511) >> 9)
+            sectors < (mddev->bitmap->storage.bytes + 511) >> 9)
                 return -EFBIG; /* Bitmap is too big for this small space */
 
         /* could make sure it isn't too big, but that isn't really
diff --git a/drivers/md/bitmap.h b/drivers/md/bitmap.h
index 162ab095b866..26689260e179 100644
--- a/drivers/md/bitmap.h
+++ b/drivers/md/bitmap.h
@@ -197,7 +197,7 @@ struct bitmap {
                 unsigned long *filemap_attr;    /* attributes associated
                                                  * w/ filemap pages */
                 unsigned long file_pages;       /* number of pages in the file*/
-                int last_page_size;             /* bytes in the last page */
+                unsigned long bytes;            /* total bytes in the bitmap */
         } storage;
 
         unsigned long flags;