Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964946Ab3DHUuF (ORCPT ); Mon, 8 Apr 2013 16:50:05 -0400 Received: from mail-pd0-f174.google.com ([209.85.192.174]:57654 "EHLO mail-pd0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964861Ab3DHUuD (ORCPT ); Mon, 8 Apr 2013 16:50:03 -0400 Date: Mon, 8 Apr 2013 13:49:56 -0700 From: Kent Overstreet To: Gabriel Cc: linux-bcache@vger.kernel.org, linux-kernel@vger.kernel.org, Gabriel Subject: Re: [PATCH] bcache: Take data offset from the bdev superblock. Message-ID: <20130408204956.GH15749@google.com> References: <51629766.6030805@gmail.com> <1365415866-16344-1-git-send-email-g2p.code+bcache@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1365415866-16344-1-git-send-email-g2p.code+bcache@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5561 Lines: 165 On Mon, Apr 08, 2013 at 12:11:06PM +0200, Gabriel wrote: > Add a new superblock version, and consolidate related defines. So, I think BDEV_WITH_OFFSET looks ok, but what's the use case for it? I was going to add it way back but we decided not to implement the hack we thought we needed it for - if you or someone is going to use it I'll go ahead and apply it. As for BCACHE_SB_VERSION_CDEV_WITH_UUID, can you explain why you added that? I suspect it's needed but I can't remember why I didn't add it when I added the new UUID format (or perhaps I just forgot) > > Signed-off-by: Gabriel de Perthuis > --- > drivers/md/bcache/bcache.h | 23 ++++++++++++++++++----- > drivers/md/bcache/request.c | 2 +- > drivers/md/bcache/super.c | 21 ++++++++++++++++----- > 3 files changed, 35 insertions(+), 11 deletions(-) > > diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h > index f057235..8a110e6 100644 > --- a/drivers/md/bcache/bcache.h > +++ b/drivers/md/bcache/bcache.h > @@ -223,11 +223,17 @@ struct bkey { > #define BKEY_PADDED(key) \ > union { struct bkey key; uint64_t key ## _pad[BKEY_PAD]; } > > -/* Version 1: Backing device > +/* Version 0: Cache device > + * Version 1: Backing device > * Version 2: Seed pointer into btree node checksum > - * Version 3: New UUID format > + * Version 3: Cache device with new UUID format > + * Version 4: Backing device with data offset > */ > -#define BCACHE_SB_VERSION 3 > +#define BCACHE_SB_VERSION_CDEV 0 > +#define BCACHE_SB_VERSION_BDEV 1 > +#define BCACHE_SB_VERSION_CDEV_WITH_UUID 3 > +#define BCACHE_SB_VERSION_BDEV_WITH_OFFSET 4 > +#define BCACHE_SB_MAX_VERSION 4 > > #define SB_SECTOR 8 > #define SB_SIZE 4096 > @@ -236,13 +242,12 @@ struct bkey { > /* SB_JOURNAL_BUCKETS must be divisible by BITS_PER_LONG */ > #define MAX_CACHES_PER_SET 8 > > -#define BDEV_DATA_START 16 /* sectors */ > +#define BDEV_DATA_START_DEFAULT 16 /* sectors */ > > struct cache_sb { > uint64_t csum; > uint64_t offset; /* sector where this sb was written */ > uint64_t version; > -#define CACHE_BACKING_DEV 1 > > uint8_t magic[16]; > > @@ -485,6 +490,7 @@ struct cached_dev { > * where it's at. > */ > sector_t last_read; > + sector_t data_start_sector; > > /* Number of writeback bios in flight */ > atomic_t in_flight; > @@ -861,6 +867,13 @@ static inline bool key_merging_disabled(struct cache_set *c) > #endif > } > > + > +static inline bool SB_IS_BDEV(const struct cache_sb *sb) { > + return sb->version == BCACHE_SB_VERSION_BDEV > + || sb->version == BCACHE_SB_VERSION_BDEV_WITH_OFFSET; > +} > + > + > struct bbio { > unsigned submit_time_us; > union { > diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c > index 83731dc..9f74aff 100644 > --- a/drivers/md/bcache/request.c > +++ b/drivers/md/bcache/request.c > @@ -1220,7 +1220,7 @@ static void cached_dev_make_request(struct request_queue *q, struct bio *bio) > part_stat_unlock(); > > bio->bi_bdev = dc->bdev; > - bio->bi_sector += BDEV_DATA_START; > + bio->bi_sector += dc->data_start_sector; > > if (cached_dev_get(dc)) { > s = search_alloc(bio, d); > diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c > index 5fa3cd2..a409bb5 100644 > --- a/drivers/md/bcache/super.c > +++ b/drivers/md/bcache/super.c > @@ -148,7 +148,7 @@ static const char *read_super(struct cache_sb *sb, struct block_device *bdev, > goto err; > > err = "Unsupported superblock version"; > - if (sb->version > BCACHE_SB_VERSION) > + if (sb->version > BCACHE_SB_MAX_VERSION) > goto err; > > err = "Bad block/bucket size"; > @@ -168,7 +168,7 @@ static const char *read_super(struct cache_sb *sb, struct block_device *bdev, > if (get_capacity(bdev->bd_disk) < sb->bucket_size * sb->nbuckets) > goto err; > > - if (sb->version == CACHE_BACKING_DEV) > + if (SB_IS_BDEV(sb)) > goto out; > > err = "Bad UUID"; > @@ -286,7 +286,7 @@ void bcache_write_super(struct cache_set *c) > for_each_cache(ca, c, i) { > struct bio *bio = &ca->sb_bio; > > - ca->sb.version = BCACHE_SB_VERSION; > + ca->sb.version = BCACHE_SB_VERSION_CDEV_WITH_UUID; > ca->sb.seq = c->sb.seq; > ca->sb.last_mount = c->sb.last_mount; > > @@ -1047,9 +1047,20 @@ static const char *register_bdev(struct cache_sb *sb, struct page *sb_page, > dc->bdev = bdev; > dc->bdev->bd_holder = dc; > > + err = "bad start sector"; > + if (sb->version == BCACHE_SB_VERSION_BDEV) { > + dc->data_start_sector = BDEV_DATA_START_DEFAULT; > + } else { > + if (sb->keys < 1) > + goto err; > + dc->data_start_sector = sb->d[0]; > + if (dc->data_start_sector < BDEV_DATA_START_DEFAULT) > + goto err; > + } > + > g = dc->disk.disk; > > - set_capacity(g, dc->bdev->bd_part->nr_sects - 16); > + set_capacity(g, dc->bdev->bd_part->nr_sects - dc->data_start_sector); > > bch_cached_dev_request_init(dc); > > @@ -1802,7 +1813,7 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr, > if (err) > goto err_close; > > - if (sb->version == CACHE_BACKING_DEV) { > + if (SB_IS_BDEV(sb)) { > struct cached_dev *dc = kzalloc(sizeof(*dc), GFP_KERNEL); > > err = register_bdev(sb, sb_page, bdev, dc); > -- > 1.8.2.rc3.7.g35aca0e > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/