md/bitmap: record the space available for the bitmap in the superblock.
Now that bitmaps can grow and shrink it is best if we record
how much space is available. This means that when
we reduce the size of the bitmap we won't "lose" the space
for late when we might want to increase the size of the bitmap
again.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 8f681da..15dbe03 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -423,6 +423,8 @@
/* This might have been changed by a reshape */
sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);
sb->chunksize = cpu_to_le32(bitmap->mddev->bitmap_info.chunksize);
+ sb->sectors_reserved = cpu_to_le32(bitmap->mddev->
+ bitmap_info.space);
kunmap_atomic(sb);
write_page(bitmap, bitmap->storage.sb_page, 1);
}
@@ -536,6 +538,7 @@
bitmap_super_t *sb;
unsigned long chunksize, daemon_sleep, write_behind;
unsigned long long events;
+ unsigned long sectors_reserved = 0;
int err = -EINVAL;
struct page *sb_page;
@@ -573,6 +576,7 @@
chunksize = le32_to_cpu(sb->chunksize);
daemon_sleep = le32_to_cpu(sb->daemon_sleep) * HZ;
write_behind = le32_to_cpu(sb->write_behind);
+ sectors_reserved = le32_to_cpu(sb->sectors_reserved);
/* verify that the bitmap-specific fields are valid */
if (sb->magic != cpu_to_le32(BITMAP_MAGIC))
@@ -633,6 +637,9 @@
bitmap->mddev->bitmap_info.chunksize = chunksize;
bitmap->mddev->bitmap_info.daemon_sleep = daemon_sleep;
bitmap->mddev->bitmap_info.max_write_behind = write_behind;
+ if (bitmap->mddev->bitmap_info.space == 0 ||
+ bitmap->mddev->bitmap_info.space > sectors_reserved)
+ bitmap->mddev->bitmap_info.space = sectors_reserved;
if (err)
bitmap_print_sb(bitmap);
return err;