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md/bitmap: record the space available for the bitmap in the superblock.

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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>
This commit is contained in:
NeilBrown
2012-05-22 13:55:34 +10:00
parent 63aced6102
commit 1dff2b87a3
2 changed files with 10 additions and 1 deletions
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7
drivers/md/bitmap.c
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@@ -423,6 +423,8 @@ void bitmap_update_sb(struct bitmap *bitmap)
/* 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 @@ static int bitmap_read_sb(struct bitmap *bitmap)
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 @@ static int bitmap_read_sb(struct bitmap *bitmap)
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 @@ out_no_sb:
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;