diff options
author | Coly Li <colyli@suse.de> | 2020-07-25 20:00:30 +0800 |
---|---|---|
committer | Jens Axboe <axboe@kernel.dk> | 2020-07-25 07:38:20 -0600 |
commit | de1fafab649f944d97e45fc043b55a3a5a371744 (patch) | |
tree | 4734c66348053bc3b56c309a2fcc3e7aa9a869fa /drivers/md/bcache/bcache.h | |
parent | 4c1ccd0896d6a45f2159280d957afd441a7aeaba (diff) |
bcache: introduce meta_bucket_pages() related helper routines
Currently the in-memory meta data like c->uuids or c->disk_buckets
are allocated by alloc_bucket_pages(). The macro alloc_bucket_pages()
calls __get_free_pages() to allocated continuous pages with order
indicated by ilog2(bucket_pages(c)),
#define alloc_bucket_pages(gfp, c) \
((void *) __get_free_pages(__GFP_ZERO|gfp, ilog2(bucket_pages(c))))
The maximum order is defined as MAX_ORDER, the default value is 11 (and
can be overwritten by CONFIG_FORCE_MAX_ZONEORDER). In bcache code the
maximum bucket size width is 16bits, this is restricted both by KEY_SIZE
size and bucket_size size from struct cache_sb_disk. The maximum 16bits
width and power-of-2 value is (1<<15) in unit of sector (512byte). It
means the maximum value of bucket size in bytes is (1<<24) bytes a.k.a
4096 pages.
When the bucket size is set to maximum permitted value, ilog2(4096) is
12, which exceeds the default maximum order __get_free_pages() can
accepted, the failed pages allocation will fail cache set registration
procedure and print a kernel oops message for the exceeded pages order.
This patch introduces meta_bucket_pages(), meta_bucket_bytes(), and
alloc_bucket_pages() helper routines. meta_bucket_pages() indicates the
maximum pages can be allocated to meta data bucket, meta_bucket_bytes()
indicates the according maximum bytes, and alloc_bucket_pages() does
the pages allocation for meta bucket. Because meta_bucket_pages()
chooses the smaller value among the bucket size and MAX_ORDER_NR_PAGES,
it still works when MAX_ORDER overwritten by CONFIG_FORCE_MAX_ZONEORDER.
Following patches will use these helper routines to decide maximum pages
can be allocated for different meta data buckets. If the bucket size is
larger than meta_bucket_bytes(), the bcache registration can continue to
success, just the space more than meta_bucket_bytes() inside the bucket
is wasted. Comparing bcache failed for large bucket size, wasting some
space for meta data buckets is acceptable at this moment.
Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/md/bcache/bcache.h')
-rw-r--r-- | drivers/md/bcache/bcache.h | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h index 2d1743c0217a..5e1c581137af 100644 --- a/drivers/md/bcache/bcache.h +++ b/drivers/md/bcache/bcache.h @@ -762,6 +762,26 @@ struct bbio { #define bucket_bytes(c) ((c)->sb.bucket_size << 9) #define block_bytes(c) ((c)->sb.block_size << 9) +static inline unsigned int meta_bucket_pages(struct cache_sb *sb) +{ + unsigned int n, max_pages; + + max_pages = min_t(unsigned int, + __rounddown_pow_of_two(USHRT_MAX) / PAGE_SECTORS, + MAX_ORDER_NR_PAGES); + + n = sb->bucket_size / PAGE_SECTORS; + if (n > max_pages) + n = max_pages; + + return n; +} + +static inline unsigned int meta_bucket_bytes(struct cache_sb *sb) +{ + return meta_bucket_pages(sb) << PAGE_SHIFT; +} + #define prios_per_bucket(c) \ ((bucket_bytes(c) - sizeof(struct prio_set)) / \ sizeof(struct bucket_disk)) |