Hi,
On 5/28/20 8:34 PM, Goffredo Baroncelli wrote:
> From: Goffredo Baroncelli <kreijack@xxxxxxxxx>
>
> When this mode is enabled,
The commit message does not mention if this is either only a convenience
during development and testing of the feature to be able to quickly turn
it on/off, or if you intend to have this into the final change set.
> the allocation policy of the chunk
> is so modified:
> - allocation of metadata chunk: priority is given to preferred_metadata
> disks.
> - allocation of data chunk: priority is given to a non preferred_metadata
> disk.
>
> When a striped profile is involved (like RAID0,5,6), the logic
> is a bit more complex. If there are enough disks, the data profiles
> are stored on the non preferred_metadata disks; instead the metadata
> profiles are stored on the preferred_metadata disk.
> If the disks are not enough, then the profile is allocated on all
> the disks.
>
> Example: assuming that sda, sdb, sdc are ssd disks, and sde, sdf are
> non preferred_metadata ones.
> A data profile raid6, will be stored on sda, sdb, sdc, sde, sdf (sde
> and sdf are not enough to host a raid5 profile).
> A metadata profile raid6, will be stored on sda, sdb, sdc (these
> are enough to host a raid6 profile).
>
> To enable this mode pass -o dedicated_metadata at mount time.
Is it dedicated_metadata or preferred_metadata?
> Signed-off-by: Goffredo Baroncelli <kreijack@xxxxxxxxx>
> ---
> fs/btrfs/ctree.h | 1 +
> fs/btrfs/super.c | 8 +++++
> fs/btrfs/volumes.c | 89 ++++++++++++++++++++++++++++++++++++++++++++--
> fs/btrfs/volumes.h | 1 +
> 4 files changed, 97 insertions(+), 2 deletions(-)
>
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 03ea7370aea7..779760fd27b1 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -1239,6 +1239,7 @@ static inline u32 BTRFS_MAX_XATTR_SIZE(const struct btrfs_fs_info *info)
> #define BTRFS_MOUNT_NOLOGREPLAY (1 << 27)
> #define BTRFS_MOUNT_REF_VERIFY (1 << 28)
> #define BTRFS_MOUNT_DISCARD_ASYNC (1 << 29)
> +#define BTRFS_MOUNT_PREFERRED_METADATA (1 << 30)
>
> #define BTRFS_DEFAULT_COMMIT_INTERVAL (30)
> #define BTRFS_DEFAULT_MAX_INLINE (2048)
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index 438ecba26557..80700dc9dcf8 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -359,6 +359,7 @@ enum {
> #ifdef CONFIG_BTRFS_FS_REF_VERIFY
> Opt_ref_verify,
> #endif
> + Opt_preferred_metadata,
> Opt_err,
> };
>
> @@ -430,6 +431,7 @@ static const match_table_t tokens = {
> #ifdef CONFIG_BTRFS_FS_REF_VERIFY
> {Opt_ref_verify, "ref_verify"},
> #endif
> + {Opt_preferred_metadata, "preferred_metadata"},
> {Opt_err, NULL},
> };
>
> @@ -881,6 +883,10 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
> btrfs_set_opt(info->mount_opt, REF_VERIFY);
> break;
> #endif
> + case Opt_preferred_metadata:
> + btrfs_set_and_info(info, PREFERRED_METADATA,
> + "enabling preferred_metadata");
> + break;
> case Opt_err:
> btrfs_err(info, "unrecognized mount option '%s'", p);
> ret = -EINVAL;
> @@ -1403,6 +1409,8 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
> #endif
> if (btrfs_test_opt(info, REF_VERIFY))
> seq_puts(seq, ",ref_verify");
> + if (btrfs_test_opt(info, PREFERRED_METADATA))
> + seq_puts(seq, ",preferred_metadata");
> seq_printf(seq, ",subvolid=%llu",
> BTRFS_I(d_inode(dentry))->root->root_key.objectid);
> seq_puts(seq, ",subvol=");
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 5265f54c2931..c68efb15e473 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -4770,6 +4770,56 @@ static int btrfs_cmp_device_info(const void *a, const void *b)
> return 0;
> }
>
> +/*
> + * sort the devices in descending order by preferred_metadata,
> + * max_avail, total_avail
> + */
> +static int btrfs_cmp_device_info_metadata(const void *a, const void *b)
> +{
> + const struct btrfs_device_info *di_a = a;
> + const struct btrfs_device_info *di_b = b;
> +
> + /* metadata -> preferred_metadata first */
> + if (di_a->preferred_metadata && !di_b->preferred_metadata)
> + return -1;
> + if (!di_a->preferred_metadata && di_b->preferred_metadata)
> + return 1;
> + if (di_a->max_avail > di_b->max_avail)
> + return -1;
> + if (di_a->max_avail < di_b->max_avail)
> + return 1;
> + if (di_a->total_avail > di_b->total_avail)
> + return -1;
> + if (di_a->total_avail < di_b->total_avail)
> + return 1;
> + return 0;
> +}
> +
> +/*
> + * sort the devices in descending order by !preferred_metadata,
> + * max_avail, total_avail
> + */
> +static int btrfs_cmp_device_info_data(const void *a, const void *b)
> +{
> + const struct btrfs_device_info *di_a = a;
> + const struct btrfs_device_info *di_b = b;
> +
> + /* data -> preferred_metadata last */
> + if (di_a->preferred_metadata && !di_b->preferred_metadata)
> + return 1;
> + if (!di_a->preferred_metadata && di_b->preferred_metadata)
> + return -1;
> + if (di_a->max_avail > di_b->max_avail)
> + return -1;
> + if (di_a->max_avail < di_b->max_avail)
> + return 1;
> + if (di_a->total_avail > di_b->total_avail)
> + return -1;
> + if (di_a->total_avail < di_b->total_avail)
> + return 1;
> + return 0;
> +}
> +
> static void check_raid56_incompat_flag(struct btrfs_fs_info *info, u64 type)
> {
> if (!(type & BTRFS_BLOCK_GROUP_RAID56_MASK))
> @@ -4885,6 +4935,7 @@ static int gather_device_info(struct btrfs_fs_devices *fs_devices,
> int ndevs = 0;
> u64 max_avail;
> u64 dev_offset;
> + int nr_preferred_metadata = 0;
>
> /*
> * in the first pass through the devices list, we gather information
> @@ -4937,15 +4988,49 @@ static int gather_device_info(struct btrfs_fs_devices *fs_devices,
> devices_info[ndevs].max_avail = max_avail;
> devices_info[ndevs].total_avail = total_avail;
> devices_info[ndevs].dev = device;
> + devices_info[ndevs].preferred_metadata = !!(device->type &
> + BTRFS_DEV_PREFERRED_METADATA);
> + if (devices_info[ndevs].preferred_metadata)
> + nr_preferred_metadata++;
> ++ndevs;
> }
> ctl->ndevs = ndevs;
>
> + BUG_ON(nr_preferred_metadata > ndevs);
> /*
> * now sort the devices by hole size / available space
> */
> - sort(devices_info, ndevs, sizeof(struct btrfs_device_info),
> - btrfs_cmp_device_info, NULL);
> + if (((ctl->type & BTRFS_BLOCK_GROUP_DATA) &&
> + (ctl->type & BTRFS_BLOCK_GROUP_METADATA)) ||
> + !btrfs_test_opt(info, PREFERRED_METADATA)) {
> + /* mixed bg or PREFERRED_METADATA not set */
> + sort(devices_info, ctl->ndevs, sizeof(struct btrfs_device_info),
> + btrfs_cmp_device_info, NULL);
> + } else {
> + /*
> + * if PREFERRED_METADATA is set, sort the device considering
> + * also the kind (preferred_metadata or not). Limit the
> + * availables devices to the ones of the same kind, to avoid
> + * that a striped profile, like raid5, spreads to all kind of
> + * devices.
> + * It is allowed to use different kinds of devices if the ones
> + * of the same kind are not enough alone.
> + */
> + if (ctl->type & BTRFS_BLOCK_GROUP_DATA) {
> + int nr_data = ctl->ndevs - nr_preferred_metadata;
> + sort(devices_info, ctl->ndevs,
> + sizeof(struct btrfs_device_info),
> + btrfs_cmp_device_info_data, NULL);
> + if (nr_data >= ctl->devs_min)
> + ctl->ndevs = nr_data;
> + } else { /* non data -> metadata and system */
> + sort(devices_info, ctl->ndevs,
> + sizeof(struct btrfs_device_info),
> + btrfs_cmp_device_info_metadata, NULL);
> + if (nr_preferred_metadata >= ctl->devs_min)
> + ctl->ndevs = nr_preferred_metadata;
> + }
> + }
>
> return 0;
> }
> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
> index 0ac5bf2b95e6..d39c3b0e7569 100644
> --- a/fs/btrfs/volumes.h
> +++ b/fs/btrfs/volumes.h
> @@ -347,6 +347,7 @@ struct btrfs_device_info {
> u64 dev_offset;
> u64 max_avail;
> u64 total_avail;
> + int preferred_metadata:1;
> };
>
> struct btrfs_raid_attr {
>
