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Message-ID: <20230912203214.GE20408@twin.jikos.cz>
Date: Tue, 12 Sep 2023 22:32:14 +0200
From: David Sterba <dsterba@...e.cz>
To: Johannes Thumshirn <johannes.thumshirn@....com>
Cc: Chris Mason <clm@...com>, Josef Bacik <josef@...icpanda.com>,
David Sterba <dsterba@...e.com>,
Christoph Hellwig <hch@....de>,
Naohiro Aota <naohiro.aota@....com>, Qu Wenruo <wqu@...e.com>,
Damien Le Moal <dlemoal@...nel.org>,
linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 01/11] btrfs: add raid stripe tree definitions
On Mon, Sep 11, 2023 at 05:52:02AM -0700, Johannes Thumshirn wrote:
> Add definitions for the raid stripe tree. This tree will hold information
> about the on-disk layout of the stripes in a RAID set.
>
> Each stripe extent has a 1:1 relationship with an on-disk extent item and
> is doing the logical to per-drive physical address translation for the
> extent item in question.
>
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@....com>
> ---
> fs/btrfs/accessors.h | 10 ++++++++++
> fs/btrfs/locking.c | 5 +++--
> include/uapi/linux/btrfs_tree.h | 33 +++++++++++++++++++++++++++++++--
> 3 files changed, 44 insertions(+), 4 deletions(-)
>
> diff --git a/fs/btrfs/accessors.h b/fs/btrfs/accessors.h
> index f958eccff477..977ff160a024 100644
> --- a/fs/btrfs/accessors.h
> +++ b/fs/btrfs/accessors.h
> @@ -306,6 +306,16 @@ BTRFS_SETGET_FUNCS(timespec_nsec, struct btrfs_timespec, nsec, 32);
> BTRFS_SETGET_STACK_FUNCS(stack_timespec_sec, struct btrfs_timespec, sec, 64);
> BTRFS_SETGET_STACK_FUNCS(stack_timespec_nsec, struct btrfs_timespec, nsec, 32);
>
> +BTRFS_SETGET_FUNCS(stripe_extent_encoding, struct btrfs_stripe_extent, encoding, 8);
What is encoding referring to?
> +BTRFS_SETGET_FUNCS(raid_stride_devid, struct btrfs_raid_stride, devid, 64);
> +BTRFS_SETGET_FUNCS(raid_stride_physical, struct btrfs_raid_stride, physical, 64);
> +BTRFS_SETGET_FUNCS(raid_stride_length, struct btrfs_raid_stride, length, 64);
> +BTRFS_SETGET_STACK_FUNCS(stack_stripe_extent_encoding,
> + struct btrfs_stripe_extent, encoding, 8);
> +BTRFS_SETGET_STACK_FUNCS(stack_raid_stride_devid, struct btrfs_raid_stride, devid, 64);
> +BTRFS_SETGET_STACK_FUNCS(stack_raid_stride_physical, struct btrfs_raid_stride, physical, 64);
> +BTRFS_SETGET_STACK_FUNCS(stack_raid_stride_length, struct btrfs_raid_stride, length, 64);
> +
> /* struct btrfs_dev_extent */
> BTRFS_SETGET_FUNCS(dev_extent_chunk_tree, struct btrfs_dev_extent, chunk_tree, 64);
> BTRFS_SETGET_FUNCS(dev_extent_chunk_objectid, struct btrfs_dev_extent,
> diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c
> index 6ac4fd8cc8dc..e7760d40feab 100644
> --- a/fs/btrfs/locking.c
> +++ b/fs/btrfs/locking.c
> @@ -58,8 +58,8 @@
>
> static struct btrfs_lockdep_keyset {
> u64 id; /* root objectid */
> - /* Longest entry: btrfs-block-group-00 */
> - char names[BTRFS_MAX_LEVEL][24];
> + /* Longest entry: btrfs-raid-stripe-tree-00 */
> + char names[BTRFS_MAX_LEVEL][25];
Length of "btrfs-raid-stripe-tree-00" is 25, there should be +1 for the
NUL, also length aligned to at least 4 is better.
> struct lock_class_key keys[BTRFS_MAX_LEVEL];
> } btrfs_lockdep_keysets[] = {
> { .id = BTRFS_ROOT_TREE_OBJECTID, DEFINE_NAME("root") },
> @@ -74,6 +74,7 @@ static struct btrfs_lockdep_keyset {
> { .id = BTRFS_UUID_TREE_OBJECTID, DEFINE_NAME("uuid") },
> { .id = BTRFS_FREE_SPACE_TREE_OBJECTID, DEFINE_NAME("free-space") },
> { .id = BTRFS_BLOCK_GROUP_TREE_OBJECTID, DEFINE_NAME("block-group") },
> + { .id = BTRFS_RAID_STRIPE_TREE_OBJECTID,DEFINE_NAME("raid-stripe-tree") },
The naming is without the "tree"
> { .id = 0, DEFINE_NAME("tree") },
> };
>
> diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
> index fc3c32186d7e..3fb758ce3ac0 100644
> --- a/include/uapi/linux/btrfs_tree.h
> +++ b/include/uapi/linux/btrfs_tree.h
> @@ -4,9 +4,8 @@
>
> #include <linux/btrfs.h>
> #include <linux/types.h>
> -#ifdef __KERNEL__
> #include <linux/stddef.h>
> -#else
> +#ifndef __KERNEL__
> #include <stddef.h>
> #endif
>
> @@ -73,6 +72,9 @@
> /* Holds the block group items for extent tree v2. */
> #define BTRFS_BLOCK_GROUP_TREE_OBJECTID 11ULL
>
> +/* tracks RAID stripes in block groups. */
Tracks ...
> +#define BTRFS_RAID_STRIPE_TREE_OBJECTID 12ULL
> +
> /* device stats in the device tree */
> #define BTRFS_DEV_STATS_OBJECTID 0ULL
>
> @@ -285,6 +287,8 @@
> */
> #define BTRFS_QGROUP_RELATION_KEY 246
>
> +#define BTRFS_RAID_STRIPE_KEY 247
Any particular reason you chose 247 for the key number? It does not
leave any gap after BTRFS_QGROUP_RELATION_KEY and before
BTRFS_BALANCE_ITEM_KEY. If this is related to extents then please find
more suitable group of keys where to put it.
> +
> /*
> * Obsolete name, see BTRFS_TEMPORARY_ITEM_KEY.
> */
> @@ -719,6 +723,31 @@ struct btrfs_free_space_header {
> __le64 num_bitmaps;
> } __attribute__ ((__packed__));
>
> +struct btrfs_raid_stride {
> + /* btrfs device-id this raid extent lives on */
Comments should be full sentences.
> + __le64 devid;
> + /* physical location on disk */
> + __le64 physical;
> + /* length of stride on this disk */
> + __le64 length;
> +};
__attribute__ ((__packed__));
> +
> +#define BTRFS_STRIPE_DUP 0
> +#define BTRFS_STRIPE_RAID0 1
> +#define BTRFS_STRIPE_RAID1 2
> +#define BTRFS_STRIPE_RAID1C3 3
> +#define BTRFS_STRIPE_RAID1C4 4
> +#define BTRFS_STRIPE_RAID5 5
> +#define BTRFS_STRIPE_RAID6 6
> +#define BTRFS_STRIPE_RAID10 7
This is probably defining the on-disk format so some consistency is
desired, there are already the BTRFS_BLOCK_GROUP_* types, from which the
BTRFS_RAID_* are derive, so the BTRFS_STRIPE_* values should match the
order and ideally the values themselves if possible.
> +
> +struct btrfs_stripe_extent {
> + __u8 encoding;
> + __u8 reserved[7];
> + /* array of raid strides this stripe is composed of */
> + __DECLARE_FLEX_ARRAY(struct btrfs_raid_stride, strides);
Do we really whant to declare that as __DECLARE_FLEX_ARRAY? It's not a
standard macro and obscures the definition.
> +};
> +
> #define BTRFS_HEADER_FLAG_WRITTEN (1ULL << 0)
> #define BTRFS_HEADER_FLAG_RELOC (1ULL << 1)
>
>
> --
> 2.41.0
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