md/bitmap: add new 'space' attribute for bitmaps.
If we are to allow bitmaps to be resized when the array is resized,
we need to know how much space there is.
So create an attribute to store this information and set appropriate
defaults.
It can be set more precisely via sysfs, or future metadata extensions
may allow it to be recorded.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/md.c b/drivers/md/md.c
index ac99616..9a677f2 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1197,7 +1197,10 @@
mddev->dev_sectors = ((sector_t)sb->size) * 2;
mddev->events = ev1;
mddev->bitmap_info.offset = 0;
+ mddev->bitmap_info.space = 0;
+ /* bitmap can use 60 K after the 4K superblocks */
mddev->bitmap_info.default_offset = MD_SB_BYTES >> 9;
+ mddev->bitmap_info.default_space = 64*2 - (MD_SB_BYTES >> 9);
mddev->reshape_backwards = 0;
if (mddev->minor_version >= 91) {
@@ -1234,9 +1237,12 @@
mddev->max_disks = MD_SB_DISKS;
if (sb->state & (1<<MD_SB_BITMAP_PRESENT) &&
- mddev->bitmap_info.file == NULL)
+ mddev->bitmap_info.file == NULL) {
mddev->bitmap_info.offset =
mddev->bitmap_info.default_offset;
+ mddev->bitmap_info.space =
+ mddev->bitmap_info.space;
+ }
} else if (mddev->pers == NULL) {
/* Insist on good event counter while assembling, except
@@ -1677,7 +1683,12 @@
mddev->dev_sectors = le64_to_cpu(sb->size);
mddev->events = ev1;
mddev->bitmap_info.offset = 0;
+ mddev->bitmap_info.space = 0;
+ /* Default location for bitmap is 1K after superblock
+ * using 3K - total of 4K
+ */
mddev->bitmap_info.default_offset = 1024 >> 9;
+ mddev->bitmap_info.default_space = (4096-1024) >> 9;
mddev->reshape_backwards = 0;
mddev->recovery_cp = le64_to_cpu(sb->resync_offset);
@@ -1686,9 +1697,23 @@
mddev->max_disks = (4096-256)/2;
if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_BITMAP_OFFSET) &&
- mddev->bitmap_info.file == NULL )
+ mddev->bitmap_info.file == NULL) {
mddev->bitmap_info.offset =
(__s32)le32_to_cpu(sb->bitmap_offset);
+ /* Metadata doesn't record how much space is available.
+ * For 1.0, we assume we can use up to the superblock
+ * if before, else to 4K beyond superblock.
+ * For others, assume no change is possible.
+ */
+ if (mddev->minor_version > 0)
+ mddev->bitmap_info.space = 0;
+ else if (mddev->bitmap_info.offset > 0)
+ mddev->bitmap_info.space =
+ 8 - mddev->bitmap_info.offset;
+ else
+ mddev->bitmap_info.space =
+ -mddev->bitmap_info.offset;
+ }
if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_RESHAPE_ACTIVE)) {
mddev->reshape_position = le64_to_cpu(sb->reshape_position);
@@ -5280,6 +5305,7 @@
mddev->merge_check_needed = 0;
mddev->bitmap_info.offset = 0;
mddev->bitmap_info.default_offset = 0;
+ mddev->bitmap_info.default_space = 0;
mddev->bitmap_info.chunksize = 0;
mddev->bitmap_info.daemon_sleep = 0;
mddev->bitmap_info.max_write_behind = 0;
@@ -6076,6 +6102,7 @@
set_bit(MD_CHANGE_DEVS, &mddev->flags);
mddev->bitmap_info.default_offset = MD_SB_BYTES >> 9;
+ mddev->bitmap_info.default_space = 64*2 - (MD_SB_BYTES >> 9);
mddev->bitmap_info.offset = 0;
mddev->reshape_position = MaxSector;
@@ -6258,6 +6285,8 @@
return -EINVAL;
mddev->bitmap_info.offset =
mddev->bitmap_info.default_offset;
+ mddev->bitmap_info.space =
+ mddev->bitmap_info.default_space;
mddev->pers->quiesce(mddev, 1);
rv = bitmap_create(mddev);
if (!rv)
