Re: [PATCH 22/43] xfs: add the zoned space allocator

Darrick J. Wong
2025-02-07T17:39:43Z

On Thu, Feb 06, 2025 at 07:44:38AM +0100, Christoph Hellwig wrote:
> For zoned RT devices space is always allocated at the write pointer, that
> is right after the last written block and only recorded on I/O completion.
>
> Because the actual allocation algorithm is very simple and just involves
> picking a good zone - preferably the one used for the last write to the
> inode. As the number of zones that can written at the same time is
> usually limited by the hardware, selecting a zone is done as late as
> possible from the iomap dio and buffered writeback bio submissions
> helpers just before submitting the bio.
>
> Given that the writers already took a reservation before acquiring the
> iolock, space will always be readily available if an open zone slot is
> available. A new structure is used to track these open zones, and
> pointed to by the xfs_rtgroup. Because zoned file systems don't have
> a rsum cache the space for that pointer can be reused.
>
> Allocations are only recorded at I/O completion time. The scheme used
> for that is very similar to the reflink COW end I/O path.
>
> Co-developed-by: Hans Holmberg <hans.holmberg@wdc.com>
> Signed-off-by: Hans Holmberg <hans.holmberg@wdc.com>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> fs/xfs/Makefile | 3 +-
> fs/xfs/libxfs/xfs_rtgroup.h | 22 +-
> fs/xfs/libxfs/xfs_types.h | 13 +-
> fs/xfs/xfs_log.c | 4 +
> fs/xfs/xfs_mount.c | 17 +-
> fs/xfs/xfs_mount.h | 2 +
> fs/xfs/xfs_rtalloc.c | 6 +-
> fs/xfs/xfs_trace.c | 2 +
> fs/xfs/xfs_trace.h | 97 ++++
> fs/xfs/xfs_zone_alloc.c | 959 ++++++++++++++++++++++++++++++++++++
> fs/xfs/xfs_zone_alloc.h | 34 ++
> fs/xfs/xfs_zone_priv.h | 89 ++++
> 12 files changed, 1238 insertions(+), 10 deletions(-)
> create mode 100644 fs/xfs/xfs_zone_alloc.c
> create mode 100644 fs/xfs/xfs_zone_alloc.h
> create mode 100644 fs/xfs/xfs_zone_priv.h
>
> diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
> index ea8e66c1e969..28bd2627e9ef 100644
> --- a/fs/xfs/Makefile
> +++ b/fs/xfs/Makefile
> @@ -137,7 +137,8 @@ xfs-$(CONFIG_XFS_QUOTA) += xfs_dquot.o \
> xfs_quotaops.o
>
> # xfs_rtbitmap is shared with libxfs
> -xfs-$(CONFIG_XFS_RT) += xfs_rtalloc.o
> +xfs-$(CONFIG_XFS_RT) += xfs_rtalloc.o \
> + xfs_zone_alloc.o
>
> xfs-$(CONFIG_XFS_POSIX_ACL) += xfs_acl.o
> xfs-$(CONFIG_SYSCTL) += xfs_sysctl.o
> diff --git a/fs/xfs/libxfs/xfs_rtgroup.h b/fs/xfs/libxfs/xfs_rtgroup.h
> index e35d1d798327..5d8777f819f4 100644
> --- a/fs/xfs/libxfs/xfs_rtgroup.h
> +++ b/fs/xfs/libxfs/xfs_rtgroup.h
> @@ -37,15 +37,27 @@ struct xfs_rtgroup {
> xfs_rtxnum_t rtg_extents;
>
> /*
> - * Cache of rt summary level per bitmap block with the invariant that
> - * rtg_rsum_cache[bbno] > the maximum i for which rsum[i][bbno] != 0,
> - * or 0 if rsum[i][bbno] == 0 for all i.
> - *
> + * For bitmap based RT devices this points to a cache of rt summary
> + * level per bitmap block with the invariant that rtg_rsum_cache[bbno]
> + * > the maximum i for which rsum[i][bbno] != 0, or 0 if
> + * rsum[i][bbno] == 0 for all i.
> * Reads and writes are serialized by the rsumip inode lock.
> + *
> + * For zoned RT devices this points to the open zone structure for
> + * a group that is open for writers, or is NULL.
> */
> - uint8_t *rtg_rsum_cache;
> + union {
> + uint8_t *rtg_rsum_cache;
> + struct xfs_open_zone *rtg_open_zone;
> + };
> };
>
> +/*
> + * For zoned RT devices this is set on groups that have no written blocks
> + * and can be picked by the allocator for opening.
> + */
> +#define XFS_RTG_FREE XA_MARK_0
> +
> static inline struct xfs_rtgroup *to_rtg(struct xfs_group *xg)
> {
> return container_of(xg, struct xfs_rtgroup, rtg_group);
> diff --git a/fs/xfs/libxfs/xfs_types.h b/fs/xfs/libxfs/xfs_types.h
> index 76f3c31573ec..f6f4f2d4b5db 100644
> --- a/fs/xfs/libxfs/xfs_types.h
> +++ b/fs/xfs/libxfs/xfs_types.h
> @@ -243,12 +243,23 @@ enum xfs_free_counter {
> * Number of free RT extents on the RT device.
> */
> XC_FREE_RTEXTENTS,
> +
> + /*
> + * Number of available for use RT extents.
> + *
> + * This counter only exists for zoned RT device and indicates the number
> + * of RT extents that can be directly used by writes. XC_FREE_RTEXTENTS
> + * also includes blocks that have been written previously and freed, but
> + * sit in a rtgroup that still needs a zone reset.
> + */
> + XC_FREE_RTAVAILABLE,
> XC_FREE_NR,
> };
>
> #define XFS_FREECOUNTER_STR \
> { XC_FREE_BLOCKS, "blocks" }, \
> - { XC_FREE_RTEXTENTS, "rtextents" }
> + { XC_FREE_RTEXTENTS, "rtextents" }, \
> + { XC_FREE_RTAVAILABLE, "rtavailable" }
>
> /*
> * Type verifier functions
> diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
> index f8851ff835de..6493bdb57351 100644
> --- a/fs/xfs/xfs_log.c
> +++ b/fs/xfs/xfs_log.c
> @@ -20,6 +20,7 @@
> #include "xfs_sysfs.h"
> #include "xfs_sb.h"
> #include "xfs_health.h"
> +#include "xfs_zone_alloc.h"
>
> struct kmem_cache *xfs_log_ticket_cache;
>
> @@ -3540,6 +3541,9 @@ xlog_force_shutdown(
> spin_unlock(&log->l_icloglock);
>
> wake_up_var(&log->l_opstate);
> + if (IS_ENABLED(CONFIG_XFS_RT) && xfs_has_zoned(log->l_mp))
> + xfs_zoned_wake_all(log->l_mp);
> +
> return log_error;
> }
>
> diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
> index b6004e456ed3..06e34c43cc94 100644
> --- a/fs/xfs/xfs_mount.c
> +++ b/fs/xfs/xfs_mount.c
> @@ -40,6 +40,7 @@
> #include "xfs_rtrmap_btree.h"
> #include "xfs_rtrefcount_btree.h"
> #include "scrub/stats.h"
> +#include "xfs_zone_alloc.h"
>
> static DEFINE_MUTEX(xfs_uuid_table_mutex);
> static int xfs_uuid_table_size;
> @@ -467,6 +468,7 @@ xfs_mount_reset_sbqflags(
> static const char *const xfs_free_pool_name[] = {
> [XC_FREE_BLOCKS] = "free blocks",
> [XC_FREE_RTEXTENTS] = "free rt extents",
> + [XC_FREE_RTAVAILABLE] = "available rt extents",
> };
>
> uint64_t
> @@ -1045,6 +1047,12 @@ xfs_mountfs(
> if (xfs_is_readonly(mp) && !xfs_has_norecovery(mp))
> xfs_log_clean(mp);
>
> + if (xfs_has_zoned(mp)) {
> + error = xfs_mount_zones(mp);
> + if (error)
> + goto out_rtunmount;
> + }
> +
> /*
> * Complete the quota initialisation, post-log-replay component.
> */
> @@ -1087,6 +1095,8 @@ xfs_mountfs(
> out_agresv:
> xfs_fs_unreserve_ag_blocks(mp);
> xfs_qm_unmount_quotas(mp);
> + if (xfs_has_zoned(mp))
> + xfs_unmount_zones(mp);
> out_rtunmount:
> xfs_rtunmount_inodes(mp);
> out_rele_rip:
> @@ -1168,6 +1178,8 @@ xfs_unmountfs(
> xfs_blockgc_stop(mp);
> xfs_fs_unreserve_ag_blocks(mp);
> xfs_qm_unmount_quotas(mp);
> + if (xfs_has_zoned(mp))
> + xfs_unmount_zones(mp);
> xfs_rtunmount_inodes(mp);
> xfs_irele(mp->m_rootip);
> if (mp->m_metadirip)
> @@ -1251,7 +1263,7 @@ xfs_freecounter_unavailable(
> struct xfs_mount *mp,
> enum xfs_free_counter ctr)
> {
> - if (ctr == XC_FREE_RTEXTENTS)
> + if (ctr == XC_FREE_RTEXTENTS || ctr == XC_FREE_RTAVAILABLE)
> return 0;
> return mp->m_alloc_set_aside + atomic64_read(&mp->m_allocbt_blks);
> }
> @@ -1341,7 +1353,8 @@ xfs_dec_freecounter(
>
> lcounter = (long long)mp->m_resblks[ctr].avail - delta;
> if (lcounter < 0) {
> - xfs_warn_once(mp,
> + if (ctr == XC_FREE_BLOCKS)
> + xfs_warn_once(mp,

That probably should go in the patch enabling xfs_dec_freecounter to
take XC_FREE_RTEXTENTS.

> "Reserve blocks depleted! Consider increasing reserve pool size.");
> goto fdblocks_enospc;
> }
> diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
> index 7c29f3f9ba78..a0e51ce5b84c 100644
> --- a/fs/xfs/xfs_mount.h
> +++ b/fs/xfs/xfs_mount.h
> @@ -205,6 +205,7 @@ typedef struct xfs_mount {
> bool m_fail_unmount;
> bool m_finobt_nores; /* no per-AG finobt resv. */
> bool m_update_sb; /* sb needs update in mount */
> + unsigned int m_max_open_zones;
>
> /*
> * Bitsets of per-fs metadata that have been checked and/or are sick.
> @@ -257,6 +258,7 @@ typedef struct xfs_mount {
> uint64_t save; /* reserved blks @ remount,ro */
> } m_resblks[XC_FREE_NR];
> struct delayed_work m_reclaim_work; /* background inode reclaim */
> + struct xfs_zone_info *m_zone_info; /* zone allocator information */
> struct dentry *m_debugfs; /* debugfs parent */
> struct xfs_kobj m_kobj;
> struct xfs_kobj m_error_kobj;
> diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
> index a0fd1dc5d362..6a45749daf57 100644
> --- a/fs/xfs/xfs_rtalloc.c
> +++ b/fs/xfs/xfs_rtalloc.c
> @@ -33,6 +33,7 @@
> #include "xfs_trace.h"
> #include "xfs_rtrefcount_btree.h"
> #include "xfs_reflink.h"
> +#include "xfs_zone_alloc.h"
>
> /*
> * Return whether there are any free extents in the size range given
> @@ -663,7 +664,8 @@ xfs_rtunmount_rtg(
>
> for (i = 0; i < XFS_RTGI_MAX; i++)
> xfs_rtginode_irele(&rtg->rtg_inodes[i]);
> - kvfree(rtg->rtg_rsum_cache);
> + if (!xfs_has_zoned(rtg_mount(rtg)))
> + kvfree(rtg->rtg_rsum_cache);
> }
>
> static int
> @@ -1573,6 +1575,8 @@ xfs_rtmount_rtg(
> }
> }
>
> + if (xfs_has_zoned(mp))
> + return 0;
> return xfs_alloc_rsum_cache(rtg, mp->m_sb.sb_rbmblocks);
> }
>
> diff --git a/fs/xfs/xfs_trace.c b/fs/xfs/xfs_trace.c
> index 8f530e69c18a..a60556dbd172 100644
> --- a/fs/xfs/xfs_trace.c
> +++ b/fs/xfs/xfs_trace.c
> @@ -49,6 +49,8 @@
> #include "xfs_metafile.h"
> #include "xfs_metadir.h"
> #include "xfs_rtgroup.h"
> +#include "xfs_zone_alloc.h"
> +#include "xfs_zone_priv.h"
>
> /*
> * We include this last to have the helpers above available for the trace
> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> index a02129c202b2..d4f012e41564 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -102,6 +102,7 @@ struct xfs_rmap_intent;
> struct xfs_refcount_intent;
> struct xfs_metadir_update;
> struct xfs_rtgroup;
> +struct xfs_open_zone;
>
> #define XFS_ATTR_FILTER_FLAGS \
> { XFS_ATTR_ROOT, "ROOT" }, \
> @@ -265,6 +266,100 @@ DEFINE_GROUP_REF_EVENT(xfs_group_grab);
> DEFINE_GROUP_REF_EVENT(xfs_group_grab_next_tag);
> DEFINE_GROUP_REF_EVENT(xfs_group_rele);
>
> +#ifdef CONFIG_XFS_RT
> +DECLARE_EVENT_CLASS(xfs_zone_class,
> + TP_PROTO(struct xfs_rtgroup *rtg),
> + TP_ARGS(rtg),
> + TP_STRUCT__entry(
> + __field(dev_t, dev)
> + __field(xfs_rgnumber_t, rgno)
> + __field(xfs_rgblock_t, used)
> + ),
> + TP_fast_assign(
> + __entry->dev = rtg_mount(rtg)->m_super->s_dev;
> + __entry->rgno = rtg_rgno(rtg);
> + __entry->used = rtg_rmap(rtg)->i_used_blocks;
> + ),
> + TP_printk("dev %d:%d rgno 0x%x used 0x%x",
> + MAJOR(__entry->dev), MINOR(__entry->dev),
> + __entry->rgno,
> + __entry->used)
> +);
> +
> +#define DEFINE_ZONE_EVENT(name) \
> +DEFINE_EVENT(xfs_zone_class, name, \
> + TP_PROTO(struct xfs_rtgroup *rtg), \
> + TP_ARGS(rtg))
> +DEFINE_ZONE_EVENT(xfs_zone_full);
> +DEFINE_ZONE_EVENT(xfs_zone_activate);
> +
> +TRACE_EVENT(xfs_zone_free_blocks,
> + TP_PROTO(struct xfs_rtgroup *rtg, xfs_rgblock_t rgbno,
> + xfs_extlen_t len),
> + TP_ARGS(rtg, rgbno, len),
> + TP_STRUCT__entry(
> + __field(dev_t, dev)
> + __field(xfs_rgnumber_t, rgno)
> + __field(xfs_rgblock_t, used)
> + __field(xfs_rgblock_t, rgbno)
> + __field(xfs_extlen_t, len)
> + ),
> + TP_fast_assign(
> + __entry->dev = rtg_mount(rtg)->m_super->s_dev;
> + __entry->rgno = rtg_rgno(rtg);
> + __entry->used = rtg_rmap(rtg)->i_used_blocks;
> + __entry->rgbno = rgbno;
> + __entry->len = len;
> + ),
> + TP_printk("dev %d:%d rgno 0x%x used 0x%x rgbno 0x%x len 0x%x",
> + MAJOR(__entry->dev), MINOR(__entry->dev),
> + __entry->rgno,
> + __entry->used,
> + __entry->rgbno,
> + __entry->len)
> +);
> +
> +DECLARE_EVENT_CLASS(xfs_zone_alloc_class,
> + TP_PROTO(struct xfs_open_zone *oz, xfs_rgblock_t rgbno,
> + xfs_extlen_t len),
> + TP_ARGS(oz, rgbno, len),
> + TP_STRUCT__entry(
> + __field(dev_t, dev)
> + __field(xfs_rgnumber_t, rgno)
> + __field(xfs_rgblock_t, used)
> + __field(xfs_rgblock_t, written)
> + __field(xfs_rgblock_t, write_pointer)
> + __field(xfs_rgblock_t, rgbno)
> + __field(xfs_extlen_t, len)
> + ),
> + TP_fast_assign(
> + __entry->dev = rtg_mount(oz->oz_rtg)->m_super->s_dev;
> + __entry->rgno = rtg_rgno(oz->oz_rtg);
> + __entry->used = rtg_rmap(oz->oz_rtg)->i_used_blocks;
> + __entry->written = oz->oz_written;
> + __entry->write_pointer = oz->oz_write_pointer;
> + __entry->rgbno = rgbno;
> + __entry->len = len;
> + ),
> + TP_printk("dev %d:%d rgno 0x%x used 0x%x written 0x%x wp 0x%x rgbno 0x%x len 0x%x",
> + MAJOR(__entry->dev), MINOR(__entry->dev),
> + __entry->rgno,
> + __entry->used,
> + __entry->written,
> + __entry->write_pointer,
> + __entry->rgbno,
> + __entry->len)
> +);
> +
> +#define DEFINE_ZONE_ALLOC_EVENT(name) \
> +DEFINE_EVENT(xfs_zone_alloc_class, name, \
> + TP_PROTO(struct xfs_open_zone *oz, xfs_rgblock_t rgbno, \
> + xfs_extlen_t len), \
> + TP_ARGS(oz, rgbno, len))
> +DEFINE_ZONE_ALLOC_EVENT(xfs_zone_record_blocks);
> +DEFINE_ZONE_ALLOC_EVENT(xfs_zone_alloc_blocks);
> +#endif /* CONFIG_XFS_RT */
> +
> TRACE_EVENT(xfs_inodegc_worker,
> TP_PROTO(struct xfs_mount *mp, unsigned int shrinker_hits),
> TP_ARGS(mp, shrinker_hits),
> @@ -3982,6 +4077,7 @@ DEFINE_SIMPLE_IO_EVENT(xfs_reflink_cancel_cow_range);
> DEFINE_SIMPLE_IO_EVENT(xfs_reflink_end_cow);
> DEFINE_INODE_IREC_EVENT(xfs_reflink_cow_remap_from);
> DEFINE_INODE_IREC_EVENT(xfs_reflink_cow_remap_to);
> +DEFINE_INODE_IREC_EVENT(xfs_reflink_cow_remap_skip);
>
> DEFINE_INODE_ERROR_EVENT(xfs_reflink_cancel_cow_range_error);
> DEFINE_INODE_ERROR_EVENT(xfs_reflink_end_cow_error);
> @@ -5665,6 +5761,7 @@ TRACE_EVENT(xfs_growfs_check_rtgeom,
>
> TRACE_DEFINE_ENUM(XC_FREE_BLOCKS);
> TRACE_DEFINE_ENUM(XC_FREE_RTEXTENTS);
> +TRACE_DEFINE_ENUM(XC_FREE_RTAVAILABLE);
>
> DECLARE_EVENT_CLASS(xfs_freeblocks_class,
> TP_PROTO(struct xfs_mount *mp, enum xfs_free_counter ctr,
> diff --git a/fs/xfs/xfs_zone_alloc.c b/fs/xfs/xfs_zone_alloc.c
> new file mode 100644
> index 000000000000..f41a2cc84382
> --- /dev/null
> +++ b/fs/xfs/xfs_zone_alloc.c
> @@ -0,0 +1,959 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2023-2025 Christoph Hellwig.
> + * Copyright (c) 2024-2025, Western Digital Corporation or its affiliates.
> + */
> +#include "xfs.h"
> +#include "xfs_shared.h"
> +#include "xfs_format.h"
> +#include "xfs_log_format.h"
> +#include "xfs_error.h"
> +#include "xfs_trans_resv.h"
> +#include "xfs_mount.h"
> +#include "xfs_inode.h"
> +#include "xfs_iomap.h"
> +#include "xfs_trans.h"
> +#include "xfs_alloc.h"
> +#include "xfs_bmap.h"
> +#include "xfs_bmap_btree.h"
> +#include "xfs_trans_space.h"
> +#include "xfs_refcount.h"
> +#include "xfs_rtbitmap.h"
> +#include "xfs_rtrmap_btree.h"
> +#include "xfs_zone_alloc.h"
> +#include "xfs_zone_priv.h"
> +#include "xfs_zones.h"
> +#include "xfs_trace.h"
> +
> +void
> +xfs_open_zone_put(
> + struct xfs_open_zone *oz)
> +{
> + if (atomic_dec_and_test(&oz->oz_ref)) {
> + xfs_rtgroup_rele(oz->oz_rtg);
> + kfree(oz);
> + }
> +}
> +
> +static void
> +xfs_open_zone_mark_full(
> + struct xfs_open_zone *oz)
> +{
> + struct xfs_rtgroup *rtg = oz->oz_rtg;
> + struct xfs_mount *mp = rtg_mount(rtg);
> + struct xfs_zone_info *zi = mp->m_zone_info;
> +
> + trace_xfs_zone_full(rtg);
> +
> + WRITE_ONCE(rtg->rtg_open_zone, NULL);
> +
> + spin_lock(&zi->zi_open_zones_lock);
> + if (oz->oz_is_gc) {
> + ASSERT(current == zi->zi_gc_thread);
> + zi->zi_open_gc_zone = NULL;
> + } else {
> + zi->zi_nr_open_zones--;
> + list_del_init(&oz->oz_entry);
> + }
> + spin_unlock(&zi->zi_open_zones_lock);
> + xfs_open_zone_put(oz);
> +
> + wake_up_all(&zi->zi_zone_wait);
> +}
> +
> +static void
> +xfs_zone_record_blocks(
> + struct xfs_trans *tp,
> + xfs_fsblock_t fsbno,
> + xfs_filblks_t len,
> + struct xfs_open_zone *oz,
> + bool used)
> +{
> + struct xfs_mount *mp = tp->t_mountp;
> + struct xfs_rtgroup *rtg = oz->oz_rtg;
> + struct xfs_inode *rmapip = rtg_rmap(rtg);
> +
> + trace_xfs_zone_record_blocks(oz, xfs_rtb_to_rgbno(mp, fsbno), len);
> +
> + xfs_rtgroup_lock(rtg, XFS_RTGLOCK_RMAP);
> + xfs_rtgroup_trans_join(tp, rtg, XFS_RTGLOCK_RMAP);
> + if (used) {
> + rmapip->i_used_blocks += len;
> + ASSERT(rmapip->i_used_blocks <= rtg_blocks(rtg));
> + } else {
> + xfs_add_frextents(mp, len);
> + }
> + oz->oz_written += len;
> + if (oz->oz_written == rtg_blocks(rtg))
> + xfs_open_zone_mark_full(oz);
> + xfs_trans_log_inode(tp, rmapip, XFS_ILOG_CORE);
> +}
> +
> +static int
> +xfs_zoned_map_extent(
> + struct xfs_trans *tp,
> + struct xfs_inode *ip,
> + struct xfs_bmbt_irec *new,
> + struct xfs_open_zone *oz,
> + xfs_fsblock_t old_startblock)
> +{
> + struct xfs_bmbt_irec data;
> + int nmaps = 1;
> + int error;
> +
> + /* Grab the corresponding mapping in the data fork. */
> + error = xfs_bmapi_read(ip, new->br_startoff, new->br_blockcount, &data,
> + &nmaps, 0);
> + if (error)
> + return error;
> +
> + /*
> + * Cap the update to the existing extent in the data fork because we can
> + * only overwrite one extent at a time.
> + */
> + ASSERT(new->br_blockcount >= data.br_blockcount);
> + new->br_blockcount = data.br_blockcount;
> +
> + /*
> + * If a data write raced with this GC write, keep the existing data in
> + * the data fork, mark our newly written GC extent as reclaimable, then
> + * move on to the next extent.
> + */
> + if (old_startblock != NULLFSBLOCK &&
> + old_startblock != data.br_startblock)
> + goto skip;
> +
> + trace_xfs_reflink_cow_remap_from(ip, new);
> + trace_xfs_reflink_cow_remap_to(ip, &data);
> +
> + error = xfs_iext_count_extend(tp, ip, XFS_DATA_FORK,
> + XFS_IEXT_REFLINK_END_COW_CNT);
> + if (error)
> + return error;
> +
> + if (data.br_startblock != HOLESTARTBLOCK) {
> + ASSERT(data.br_startblock != DELAYSTARTBLOCK);
> + ASSERT(!isnullstartblock(data.br_startblock));
> +
> + xfs_bmap_unmap_extent(tp, ip, XFS_DATA_FORK, &data);
> + if (xfs_is_reflink_inode(ip)) {
> + xfs_refcount_decrease_extent(tp, true, &data);
> + } else {
> + error = xfs_free_extent_later(tp, data.br_startblock,
> + data.br_blockcount, NULL,
> + XFS_AG_RESV_NONE,
> + XFS_FREE_EXTENT_REALTIME);
> + if (error)
> + return error;
> + }
> + }
> +
> + xfs_zone_record_blocks(tp, new->br_startblock, new->br_blockcount, oz,
> + true);
> +
> + /* Map the new blocks into the data fork. */
> + xfs_bmap_map_extent(tp, ip, XFS_DATA_FORK, new);
> + return 0;
> +
> +skip:
> + trace_xfs_reflink_cow_remap_skip(ip, new);
> + xfs_zone_record_blocks(tp, new->br_startblock, new->br_blockcount, oz,
> + false);
> + return 0;
> +}
> +
> +int
> +xfs_zoned_end_io(
> + struct xfs_inode *ip,
> + xfs_off_t offset,
> + xfs_off_t count,
> + xfs_daddr_t daddr,
> + struct xfs_open_zone *oz,
> + xfs_fsblock_t old_startblock)
> +{
> + struct xfs_mount *mp = ip->i_mount;
> + xfs_fileoff_t end_fsb = XFS_B_TO_FSB(mp, offset + count);
> + struct xfs_bmbt_irec new = {
> + .br_startoff = XFS_B_TO_FSBT(mp, offset),
> + .br_startblock = xfs_daddr_to_rtb(mp, daddr),
> + .br_state = XFS_EXT_NORM,
> + };
> + unsigned int resblks =
> + XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
> + struct xfs_trans *tp;
> + int error;
> +
> + if (xfs_is_shutdown(mp))
> + return -EIO;
> +
> + while (new.br_startoff < end_fsb) {
> + new.br_blockcount = end_fsb - new.br_startoff;
> +
> + error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0,
> + XFS_TRANS_RESERVE | XFS_TRANS_RES_FDBLKS, &tp);
> + if (error)
> + return error;
> + xfs_ilock(ip, XFS_ILOCK_EXCL);
> + xfs_trans_ijoin(tp, ip, 0);
> +
> + error = xfs_zoned_map_extent(tp, ip, &new, oz, old_startblock);
> + if (error)
> + xfs_trans_cancel(tp);
> + else
> + error = xfs_trans_commit(tp);
> + xfs_iunlock(ip, XFS_ILOCK_EXCL);
> + if (error)
> + return error;
> +
> + new.br_startoff += new.br_blockcount;
> + new.br_startblock += new.br_blockcount;
> + if (old_startblock != NULLFSBLOCK)
> + old_startblock += new.br_blockcount;
> + }
> +
> + return 0;
> +}
> +
> +/*
> + * "Free" blocks allocated in a zone.
> + *
> + * Just decrement the used blocks counter and report the space as freed.
> + */
> +int
> +xfs_zone_free_blocks(
> + struct xfs_trans *tp,
> + struct xfs_rtgroup *rtg,
> + xfs_fsblock_t fsbno,
> + xfs_filblks_t len)
> +{
> + struct xfs_mount *mp = tp->t_mountp;
> + struct xfs_inode *rmapip = rtg_rmap(rtg);
> +
> + xfs_assert_ilocked(rmapip, XFS_ILOCK_EXCL);
> +
> + if (len > rmapip->i_used_blocks) {
> + xfs_err(mp,
> +"trying to free more blocks (%lld) than used counter (%u).",
> + len, rmapip->i_used_blocks);
> + ASSERT(len <= rmapip->i_used_blocks);
> + xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
> + return -EFSCORRUPTED;
> + }
> +
> + trace_xfs_zone_free_blocks(rtg, xfs_rtb_to_rgbno(mp, fsbno), len);
> +
> + rmapip->i_used_blocks -= len;
> + xfs_add_frextents(mp, len);
> + xfs_trans_log_inode(tp, rmapip, XFS_ILOG_CORE);
> + return 0;
> +}
> +
> +/*
> + * Check if the zone containing the data just before the offset we are
> + * writing to is still open and has space.
> + */
> +static struct xfs_open_zone *
> +xfs_last_used_zone(
> + struct iomap_ioend *ioend)
> +{
> + struct xfs_inode *ip = XFS_I(ioend->io_inode);
> + struct xfs_mount *mp = ip->i_mount;
> + xfs_fileoff_t offset_fsb = XFS_B_TO_FSB(mp, ioend->io_offset);
> + struct xfs_rtgroup *rtg = NULL;
> + struct xfs_open_zone *oz = NULL;
> + struct xfs_iext_cursor icur;
> + struct xfs_bmbt_irec got;
> +
> + xfs_ilock(ip, XFS_ILOCK_SHARED);
> + if (!xfs_iext_lookup_extent_before(ip, &ip->i_df, &offset_fsb,
> + &icur, &got)) {
> + xfs_iunlock(ip, XFS_ILOCK_SHARED);
> + return NULL;
> + }
> + xfs_iunlock(ip, XFS_ILOCK_SHARED);
> +
> + rtg = xfs_rtgroup_grab(mp, xfs_rtb_to_rgno(mp, got.br_startblock));
> + if (!rtg)
> + return NULL;
> +
> + xfs_ilock(rtg_rmap(rtg), XFS_ILOCK_SHARED);
> + oz = READ_ONCE(rtg->rtg_open_zone);
> + if (oz && (oz->oz_is_gc || !atomic_inc_not_zero(&oz->oz_ref)))
> + oz = NULL;
> + xfs_iunlock(rtg_rmap(rtg), XFS_ILOCK_SHARED);
> +
> + xfs_rtgroup_rele(rtg);
> + return oz;
> +}
> +
> +static struct xfs_group *
> +xfs_find_free_zone(
> + struct xfs_mount *mp,
> + unsigned long start,
> + unsigned long end)
> +{
> + struct xfs_zone_info *zi = mp->m_zone_info;
> + XA_STATE (xas, &mp->m_groups[XG_TYPE_RTG].xa, start);
> + struct xfs_group *xg;
> +
> + xas_lock(&xas);
> + xas_for_each_marked(&xas, xg, end, XFS_RTG_FREE)
> + if (atomic_inc_not_zero(&xg->xg_active_ref))
> + goto found;
> + xas_unlock(&xas);
> + return NULL;
> +
> +found:
> + xas_clear_mark(&xas, XFS_RTG_FREE);
> + atomic_dec(&zi->zi_nr_free_zones);
> + zi->zi_free_zone_cursor = xg->xg_gno;
> + xas_unlock(&xas);
> + return xg;
> +}
> +
> +static struct xfs_open_zone *
> +xfs_init_open_zone(
> + struct xfs_rtgroup *rtg,
> + xfs_rgblock_t write_pointer,
> + bool is_gc)
> +{
> + struct xfs_open_zone *oz;
> +
> + oz = kzalloc(sizeof(*oz), GFP_NOFS | __GFP_NOFAIL);
> + spin_lock_init(&oz->oz_alloc_lock);
> + atomic_set(&oz->oz_ref, 1);
> + oz->oz_rtg = rtg;
> + oz->oz_write_pointer = write_pointer;
> + oz->oz_written = write_pointer;
> + oz->oz_is_gc = is_gc;
> +
> + /*
> + * All dereferences of rtg->rtg_open_zone hold the ILOCK for the rmap
> + * inode, but we don't really want to take that here because we are
> + * under the zone_list_lock. Ensure the pointer is only set for a fully
> + * initialized open zone structure so that a racy lookup finding it is
> + * fine.
> + */
> + WRITE_ONCE(rtg->rtg_open_zone, oz);
> + return oz;
> +}
> +
> +/*
> + * Find a completely free zone, open it, and return a reference.
> + */
> +struct xfs_open_zone *
> +xfs_open_zone(
> + struct xfs_mount *mp,
> + bool is_gc)
> +{
> + struct xfs_zone_info *zi = mp->m_zone_info;
> + struct xfs_group *xg;
> +
> + xg = xfs_find_free_zone(mp, zi->zi_free_zone_cursor, ULONG_MAX);
> + if (!xg)
> + xg = xfs_find_free_zone(mp, 0, zi->zi_free_zone_cursor);
> + if (!xg)
> + return NULL;
> +
> + set_current_state(TASK_RUNNING);
> + return xfs_init_open_zone(to_rtg(xg), 0, is_gc);
> +}
> +
> +static struct xfs_open_zone *
> +xfs_try_open_zone(
> + struct xfs_mount *mp)
> +{
> + struct xfs_zone_info *zi = mp->m_zone_info;
> + struct xfs_open_zone *oz;
> +
> + if (zi->zi_nr_open_zones >= mp->m_max_open_zones - XFS_OPEN_GC_ZONES)
> + return NULL;
> + if (atomic_read(&zi->zi_nr_free_zones) <
> + XFS_GC_ZONES - XFS_OPEN_GC_ZONES)
> + return NULL;
> +
> + /*
> + * Increment the open zone count to reserve our slot before dropping
> + * zi_open_zones_lock.
> + */
> + zi->zi_nr_open_zones++;
> + spin_unlock(&zi->zi_open_zones_lock);
> + oz = xfs_open_zone(mp, false);
> + spin_lock(&zi->zi_open_zones_lock);
> + if (!oz) {
> + zi->zi_nr_open_zones--;
> + return NULL;
> + }
> +
> + atomic_inc(&oz->oz_ref);
> + list_add_tail(&oz->oz_entry, &zi->zi_open_zones);
> +
> + /*
> + * If this was the last free zone, other waiters might be waiting
> + * on us to write to it as well.
> + */
> + wake_up_all(&zi->zi_zone_wait);
> +
> + /* XXX: this is a little verbose, but let's keep it for now */
> + xfs_info(mp, "using zone %u (%u)",
> + rtg_rgno(oz->oz_rtg), zi->zi_nr_open_zones);

Should this XXX become a tracepoint?

> + trace_xfs_zone_activate(oz->oz_rtg);
> + return oz;
> +}
> +
> +static bool
> +xfs_try_use_zone(
> + struct xfs_zone_info *zi,
> + struct xfs_open_zone *oz)
> +{
> + if (oz->oz_write_pointer == rtg_blocks(oz->oz_rtg))
> + return false;
> + if (!atomic_inc_not_zero(&oz->oz_ref))
> + return false;
> +
> + /*
> + * If we couldn't match by inode or life time we just pick the first
> + * zone with enough space above. For that we want the least busy zone
> + * for some definition of "least" busy. For now this simple LRU
> + * algorithm that rotates every zone to the end of the list will do it,
> + * even if it isn't exactly cache friendly.
> + */
> + if (!list_is_last(&oz->oz_entry, &zi->zi_open_zones))
> + list_move_tail(&oz->oz_entry, &zi->zi_open_zones);
> + return true;
> +}
> +
> +static struct xfs_open_zone *
> +xfs_select_open_zone_lru(
> + struct xfs_zone_info *zi)
> +{
> + struct xfs_open_zone *oz;
> +
> + lockdep_assert_held(&zi->zi_open_zones_lock);
> +
> + list_for_each_entry(oz, &zi->zi_open_zones, oz_entry)
> + if (xfs_try_use_zone(zi, oz))
> + return oz;
> +
> + cond_resched_lock(&zi->zi_open_zones_lock);
> + return NULL;
> +}
> +
> +static struct xfs_open_zone *
> +xfs_select_open_zone_mru(
> + struct xfs_zone_info *zi)
> +{
> + struct xfs_open_zone *oz;
> +
> + lockdep_assert_held(&zi->zi_open_zones_lock);
> +
> + list_for_each_entry_reverse(oz, &zi->zi_open_zones, oz_entry)
> + if (xfs_try_use_zone(zi, oz))
> + return oz;
> +
> + cond_resched_lock(&zi->zi_open_zones_lock);
> + return NULL;
> +}
> +
> +/*
> + * Try to pack inodes that are written back after they were closed tight instead
> + * of trying to open new zones for them or spread them to the least recently
> + * used zone. This optimizes the data layout for workloads that untar or copy
> + * a lot of small files. Right now this does not separate multiple such
> + * streams.
> + */
> +static inline bool xfs_zoned_pack_tight(struct xfs_inode *ip)
> +{
> + return !inode_is_open_for_write(VFS_I(ip)) &&
> + !(ip->i_diflags & XFS_DIFLAG_APPEND);
> +}
> +
> +/*
> + * Pick a new zone for writes.
> + *
> + * If we aren't using up our budget of open zones just open a new one from the
> + * freelist. Else try to find one that matches the expected data lifetime. If
> + * we don't find one that is good pick any zone that is available.
> + */
> +static struct xfs_open_zone *
> +xfs_select_zone_nowait(
> + struct xfs_mount *mp,
> + bool pack_tight)
> +{
> + struct xfs_zone_info *zi = mp->m_zone_info;
> + struct xfs_open_zone *oz = NULL;
> +
> + if (xfs_is_shutdown(mp))
> + return NULL;
> +
> + spin_lock(&zi->zi_open_zones_lock);
> + if (pack_tight)
> + oz = xfs_select_open_zone_mru(zi);
> + if (oz)
> + goto out_unlock;
> +
> + /*
> + * See if we can open a new zone and use that.
> + */
> + oz = xfs_try_open_zone(mp);
> + if (oz)
> + goto out_unlock;
> +
> + oz = xfs_select_open_zone_lru(zi);
> +out_unlock:
> + spin_unlock(&zi->zi_open_zones_lock);
> + return oz;
> +}
> +
> +static struct xfs_open_zone *
> +xfs_select_zone(
> + struct xfs_mount *mp,
> + bool pack_tight)
> +{
> + struct xfs_zone_info *zi = mp->m_zone_info;
> + DEFINE_WAIT (wait);
> + struct xfs_open_zone *oz;
> +
> + oz = xfs_select_zone_nowait(mp, pack_tight);
> + if (oz)
> + return oz;
> +
> + for (;;) {
> + prepare_to_wait(&zi->zi_zone_wait, &wait, TASK_UNINTERRUPTIBLE);
> + oz = xfs_select_zone_nowait(mp, pack_tight);
> + if (oz)
> + break;
> + schedule();
> + }
> + finish_wait(&zi->zi_zone_wait, &wait);
> + return oz;
> +}
> +
> +static unsigned int
> +xfs_zone_alloc_blocks(
> + struct xfs_open_zone *oz,
> + xfs_filblks_t count_fsb,
> + sector_t *sector,
> + bool *is_seq)
> +{
> + struct xfs_rtgroup *rtg = oz->oz_rtg;
> + struct xfs_mount *mp = rtg_mount(rtg);
> + xfs_rgblock_t rgbno;
> +
> + spin_lock(&oz->oz_alloc_lock);
> + count_fsb = min3(count_fsb, XFS_MAX_BMBT_EXTLEN,
> + (xfs_filblks_t)rtg_blocks(rtg) - oz->oz_write_pointer);
> + if (!count_fsb) {
> + spin_unlock(&oz->oz_alloc_lock);
> + return 0;
> + }
> + rgbno = oz->oz_write_pointer;
> + oz->oz_write_pointer += count_fsb;
> + spin_unlock(&oz->oz_alloc_lock);
> +
> + trace_xfs_zone_alloc_blocks(oz, rgbno, count_fsb);
> +
> + *sector = xfs_gbno_to_daddr(&rtg->rtg_group, 0);
> + *is_seq = bdev_zone_is_seq(mp->m_rtdev_targp->bt_bdev, *sector);
> + if (!*is_seq)
> + *sector += XFS_FSB_TO_BB(mp, rgbno);
> + return XFS_FSB_TO_B(mp, count_fsb);
> +}
> +
> +void
> +xfs_mark_rtg_boundary(
> + struct iomap_ioend *ioend)
> +{
> + struct xfs_mount *mp = XFS_I(ioend->io_inode)->i_mount;
> + sector_t sector = ioend->io_bio.bi_iter.bi_sector;
> +
> + if (xfs_rtb_to_rgbno(mp, xfs_daddr_to_rtb(mp, sector)) == 0)
> + ioend->io_flags |= IOMAP_IOEND_BOUNDARY;
> +}
> +
> +static void
> +xfs_submit_zoned_bio(
> + struct iomap_ioend *ioend,
> + struct xfs_open_zone *oz,
> + bool is_seq)
> +{
> + ioend->io_bio.bi_iter.bi_sector = ioend->io_sector;
> + ioend->io_private = oz;
> + atomic_inc(&oz->oz_ref); /* for xfs_zoned_end_io */
> +
> + if (is_seq) {
> + ioend->io_bio.bi_opf &= ~REQ_OP_WRITE;
> + ioend->io_bio.bi_opf |= REQ_OP_ZONE_APPEND;
> + } else {
> + xfs_mark_rtg_boundary(ioend);
> + }
> +
> + submit_bio(&ioend->io_bio);
> +}
> +
> +void
> +xfs_zone_alloc_and_submit(
> + struct iomap_ioend *ioend,
> + struct xfs_open_zone **oz)
> +{
> + struct xfs_inode *ip = XFS_I(ioend->io_inode);
> + struct xfs_mount *mp = ip->i_mount;
> + bool pack_tight = xfs_zoned_pack_tight(ip);
> + unsigned int alloc_len;
> + struct iomap_ioend *split;
> + bool is_seq;
> +
> + if (xfs_is_shutdown(mp))
> + goto out_error;
> +
> + /*
> + * If we don't have a cached zone in this write context, see if the
> + * last extent before the one we are writing points of an active zone.

"...writing points *to the end* of an active zone" ?

> + * If so, just continue writing to it.
> + */
> + if (!*oz && ioend->io_offset)
> + *oz = xfs_last_used_zone(ioend);

Also, why not return oz instead of passing it out via double pointer?

> + if (!*oz) {
> +select_zone:
> + *oz = xfs_select_zone(mp, pack_tight);
> + if (!*oz)
> + goto out_error;
> + }
> +
> + alloc_len = xfs_zone_alloc_blocks(*oz, XFS_B_TO_FSB(mp, ioend->io_size),
> + &ioend->io_sector, &is_seq);
> + if (!alloc_len) {
> + xfs_open_zone_put(*oz);
> + goto select_zone;
> + }
> +
> + while ((split = iomap_split_ioend(ioend, alloc_len, is_seq))) {
> + if (IS_ERR(split))
> + goto out_split_error;
> + alloc_len -= split->io_bio.bi_iter.bi_size;
> + xfs_submit_zoned_bio(split, *oz, is_seq);
> + if (!alloc_len) {
> + xfs_open_zone_put(*oz);
> + goto select_zone;
> + }
> + }
> +
> + xfs_submit_zoned_bio(ioend, *oz, is_seq);
> + return;
> +
> +out_split_error:
> + ioend->io_bio.bi_status = errno_to_blk_status(PTR_ERR(split));
> +out_error:
> + bio_io_error(&ioend->io_bio);
> +}
> +
> +void
> +xfs_zoned_wake_all(
> + struct xfs_mount *mp)
> +{
> + if (!(mp->m_super->s_flags & SB_ACTIVE))
> + return; /* can happen during log recovery */
> + wake_up_all(&mp->m_zone_info->zi_zone_wait);
> +}
> +
> +/*
> + * Check if @rgbno in @rgb is a potentially valid block. It might still be
> + * unused, but that information is only found in the rmap.
> + */
> +bool
> +xfs_zone_rgbno_is_valid(
> + struct xfs_rtgroup *rtg,
> + xfs_rgnumber_t rgbno)
> +{
> + lockdep_assert_held(&rtg_rmap(rtg)->i_lock);
> +
> + if (rtg->rtg_open_zone)
> + return rgbno < rtg->rtg_open_zone->oz_write_pointer;
> + return !xa_get_mark(&rtg_mount(rtg)->m_groups[XG_TYPE_RTG].xa,
> + rtg_rgno(rtg), XFS_RTG_FREE);
> +}
> +
> +static void
> +xfs_free_open_zones(
> + struct xfs_zone_info *zi)
> +{
> + struct xfs_open_zone *oz;
> +
> + spin_lock(&zi->zi_open_zones_lock);
> + while ((oz = list_first_entry_or_null(&zi->zi_open_zones,
> + struct xfs_open_zone, oz_entry))) {
> + list_del(&oz->oz_entry);
> + xfs_open_zone_put(oz);
> + }
> + spin_unlock(&zi->zi_open_zones_lock);
> +}
> +
> +struct xfs_init_zones {
> + struct xfs_mount *mp;
> + uint64_t available;
> + uint64_t reclaimable;
> +};
> +
> +static int
> +xfs_init_zone(
> + struct xfs_init_zones *iz,
> + struct xfs_rtgroup *rtg,
> + struct blk_zone *zone)
> +{
> + struct xfs_mount *mp = rtg_mount(rtg);
> + struct xfs_zone_info *zi = mp->m_zone_info;
> + uint64_t used = rtg_rmap(rtg)->i_used_blocks;
> + xfs_rgblock_t write_pointer, highest_rgbno;
> +
> + if (zone && !xfs_zone_validate(zone, rtg, &write_pointer))
> + return -EFSCORRUPTED;
> +
> + /*
> + * For sequential write required zones we retrieved the hardware write
> + * pointer above.
> + *
> + * For conventional zones or conventional devices we don't have that
> + * luxury. Instead query the rmap to find the highest recorded block
> + * and set the write pointer to the block after that. In case of a
> + * power loss this misses blocks where the data I/O has completed but
> + * not recorded in the rmap yet, and it also rewrites blocks if the most
> + * recently written ones got deleted again before unmount, but this is
> + * the best we can do without hardware support.
> + */
> + if (!zone || zone->cond == BLK_ZONE_COND_NOT_WP) {
> + xfs_rtgroup_lock(rtg, XFS_RTGLOCK_RMAP);
> + highest_rgbno = xfs_rtrmap_highest_rgbno(rtg);
> + if (highest_rgbno == NULLRGBLOCK)
> + write_pointer = 0;
> + else
> + write_pointer = highest_rgbno + 1;
> + xfs_rtgroup_unlock(rtg, XFS_RTGLOCK_RMAP);
> + }
> +
> + if (write_pointer == 0) {
> + /* zone is empty */
> + atomic_inc(&zi->zi_nr_free_zones);
> + xfs_group_set_mark(&rtg->rtg_group, XFS_RTG_FREE);
> + iz->available += rtg_blocks(rtg);
> + } else if (write_pointer < rtg_blocks(rtg)) {
> + /* zone is open */
> + struct xfs_open_zone *oz;
> +
> + atomic_inc(&rtg_group(rtg)->xg_active_ref);
> + oz = xfs_init_open_zone(rtg, write_pointer, false);
> + list_add_tail(&oz->oz_entry, &zi->zi_open_zones);
> + zi->zi_nr_open_zones++;
> +
> + iz->available += (rtg_blocks(rtg) - write_pointer);
> + iz->reclaimable += write_pointer - used;
> + } else if (used < rtg_blocks(rtg)) {
> + /* zone fully written, but has freed blocks */
> + iz->reclaimable += (rtg_blocks(rtg) - used);
> + }
> +
> + return 0;
> +}
> +
> +static int
> +xfs_get_zone_info_cb(
> + struct blk_zone *zone,
> + unsigned int idx,
> + void *data)
> +{
> + struct xfs_init_zones *iz = data;
> + struct xfs_mount *mp = iz->mp;
> + xfs_fsblock_t zsbno = xfs_daddr_to_rtb(mp, zone->start);
> + xfs_rgnumber_t rgno;
> + struct xfs_rtgroup *rtg;
> + int error;
> +
> + if (xfs_rtb_to_rgbno(mp, zsbno) != 0) {
> + xfs_warn(mp, "mismatched zone start 0x%llx.", zsbno);
> + return -EFSCORRUPTED;
> + }
> +
> + rgno = xfs_rtb_to_rgno(mp, zsbno);
> + rtg = xfs_rtgroup_grab(mp, rgno);
> + if (!rtg) {
> + xfs_warn(mp, "realtime group not found for zone %u.", rgno);
> + return -EFSCORRUPTED;
> + }
> + error = xfs_init_zone(iz, rtg, zone);
> + xfs_rtgroup_rele(rtg);
> + return error;
> +}
> +
> +/*
> + * Calculate the max open zone limit based on the of number of
> + * backing zones available
> + */
> +static inline uint32_t
> +xfs_max_open_zones(
> + struct xfs_mount *mp)
> +{
> + unsigned int max_open, max_open_data_zones;
> + /*
> + * We need two zones for every open data zone,
> + * one in reserve as we don't reclaim open zones. One data zone
> + * and its spare is included in XFS_MIN_ZONES.
> + */
> + max_open_data_zones = (mp->m_sb.sb_rgcount - XFS_MIN_ZONES) / 2 + 1;
> + max_open = max_open_data_zones + XFS_OPEN_GC_ZONES;
> +
> + /*
> + * Cap the max open limit to 1/4 of available space
> + */
> + max_open = min(max_open, mp->m_sb.sb_rgcount / 4);
> +
> + return max(XFS_MIN_OPEN_ZONES, max_open);
> +}
> +
> +/*
> + * Normally we use the open zone limit that the device reports. If there is
> + * none let the user pick one from the command line.
> + *
> + * If the device doesn't report an open zone limit and there is no override,
> + * allow to hold about a quarter of the zones open. In theory we could allow
> + * all to be open, but at that point we run into GC deadlocks because we can't
> + * reclaim open zones.
> + *
> + * When used on conventional SSDs a lower open limit is advisable as we'll
> + * otherwise overwhelm the FTL just as much as a conventional block allocator.
> + *
> + * Note: To debug the open zone management code, force max_open to 1 here.
> + */
> +static int
> +xfs_calc_open_zones(
> + struct xfs_mount *mp)
> +{
> + struct block_device *bdev = mp->m_rtdev_targp->bt_bdev;
> + unsigned int bdev_open_zones = bdev_max_open_zones(bdev);
> +
> + if (!mp->m_max_open_zones) {
> + if (bdev_open_zones)
> + mp->m_max_open_zones = bdev_open_zones;
> + else
> + mp->m_max_open_zones = xfs_max_open_zones(mp);
> + }
> +
> + if (mp->m_max_open_zones < XFS_MIN_OPEN_ZONES) {
> + xfs_notice(mp, "need at least %u open zones.",
> + XFS_MIN_OPEN_ZONES);
> + return -EIO;
> + }
> +
> + if (bdev_open_zones && bdev_open_zones < mp->m_max_open_zones) {
> + mp->m_max_open_zones = bdev_open_zones;
> + xfs_info(mp, "limiting open zones to %u due to hardware limit.\n",
> + bdev_open_zones);
> + }
> +
> + if (mp->m_max_open_zones > xfs_max_open_zones(mp)) {
> + mp->m_max_open_zones = xfs_max_open_zones(mp);
> + xfs_info(mp,
> +"limiting open zones to %u due to total zone count (%u)",
> + mp->m_max_open_zones, mp->m_sb.sb_rgcount);
> + }
> +
> + return 0;
> +}
> +
> +static struct xfs_zone_info *
> +xfs_alloc_zone_info(
> + struct xfs_mount *mp)
> +{
> + struct xfs_zone_info *zi;
> +
> + zi = kzalloc(sizeof(*zi), GFP_KERNEL);
> + if (!zi)
> + return NULL;
> + INIT_LIST_HEAD(&zi->zi_open_zones);
> + INIT_LIST_HEAD(&zi->zi_reclaim_reservations);
> + spin_lock_init(&zi->zi_reset_list_lock);
> + spin_lock_init(&zi->zi_open_zones_lock);
> + spin_lock_init(&zi->zi_reservation_lock);
> + init_waitqueue_head(&zi->zi_zone_wait);
> + return zi;
> +}
> +
> +static void
> +xfs_free_zone_info(
> + struct xfs_zone_info *zi)
> +{
> + xfs_free_open_zones(zi);
> + kfree(zi);
> +}
> +
> +int
> +xfs_mount_zones(
> + struct xfs_mount *mp)
> +{
> + struct xfs_init_zones iz = {
> + .mp = mp,
> + };
> + struct xfs_buftarg *bt = mp->m_rtdev_targp;
> + int error;
> +
> + if (!bt) {
> + xfs_notice(mp, "RT device missing.");
> + return -EINVAL;
> + }
> +
> + if (!xfs_has_rtgroups(mp) || !xfs_has_rmapbt(mp)) {
> + xfs_notice(mp, "invalid flag combination.");
> + return -EFSCORRUPTED;
> + }
> + if (mp->m_sb.sb_rextsize != 1) {
> + xfs_notice(mp, "zoned file systems do not support rextsize.");
> + return -EFSCORRUPTED;
> + }
> + if (mp->m_sb.sb_rgcount < XFS_MIN_ZONES) {
> + xfs_notice(mp,
> +"zoned file systems need to have at least %u zones.", XFS_MIN_ZONES);
> + return -EFSCORRUPTED;
> + }
> +
> + error = xfs_calc_open_zones(mp);
> + if (error)
> + return error;
> +
> + mp->m_zone_info = xfs_alloc_zone_info(mp);
> + if (!mp->m_zone_info)
> + return -ENOMEM;
> +
> + xfs_info(mp, "%u zones of %u blocks size (%u max open)",
> + mp->m_sb.sb_rgcount, mp->m_groups[XG_TYPE_RTG].blocks,
> + mp->m_max_open_zones);

Tracepoint?

> + if (bdev_is_zoned(bt->bt_bdev)) {
> + error = blkdev_report_zones(bt->bt_bdev,
> + XFS_FSB_TO_BB(mp, mp->m_sb.sb_rtstart),
> + mp->m_sb.sb_rgcount, xfs_get_zone_info_cb, &iz);
> + if (error < 0)
> + goto out_free_zone_info;
> + } else {
> + struct xfs_rtgroup *rtg = NULL;
> +
> + while ((rtg = xfs_rtgroup_next(mp, rtg))) {
> + error = xfs_init_zone(&iz, rtg, NULL);
> + if (error)
> + goto out_free_zone_info;
> + }
> + }
> +
> + xfs_set_freecounter(mp, XC_FREE_RTAVAILABLE, iz.available);
> + xfs_set_freecounter(mp, XC_FREE_RTEXTENTS,
> + iz.available + iz.reclaimable);

More indenting needed here.

> + return 0;
> +
> +out_free_zone_info:
> + xfs_free_zone_info(mp->m_zone_info);
> + return error;
> +}
> +
> +void
> +xfs_unmount_zones(
> + struct xfs_mount *mp)
> +{
> + xfs_free_zone_info(mp->m_zone_info);
> +}
> diff --git a/fs/xfs/xfs_zone_alloc.h b/fs/xfs/xfs_zone_alloc.h
> new file mode 100644
> index 000000000000..78cd7bfc6ac8
> --- /dev/null
> +++ b/fs/xfs/xfs_zone_alloc.h
> @@ -0,0 +1,34 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _XFS_ZONE_ALLOC_H
> +#define _XFS_ZONE_ALLOC_H
> +
> +struct iomap_ioend;
> +struct xfs_open_zone;
> +
> +void xfs_zone_alloc_and_submit(struct iomap_ioend *ioend,
> + struct xfs_open_zone **oz);
> +int xfs_zone_free_blocks(struct xfs_trans *tp, struct xfs_rtgroup *rtg,
> + xfs_fsblock_t fsbno, xfs_filblks_t len);
> +int xfs_zoned_end_io(struct xfs_inode *ip, xfs_off_t offset, xfs_off_t count,
> + xfs_daddr_t daddr, struct xfs_open_zone *oz,
> + xfs_fsblock_t old_startblock);
> +void xfs_open_zone_put(struct xfs_open_zone *oz);
> +
> +void xfs_zoned_wake_all(struct xfs_mount *mp);
> +bool xfs_zone_rgbno_is_valid(struct xfs_rtgroup *rtg, xfs_rgnumber_t rgbno);
> +void xfs_mark_rtg_boundary(struct iomap_ioend *ioend);
> +
> +#ifdef CONFIG_XFS_RT
> +int xfs_mount_zones(struct xfs_mount *mp);
> +void xfs_unmount_zones(struct xfs_mount *mp);
> +#else
> +static inline int xfs_mount_zones(struct xfs_mount *mp)
> +{
> + return -EIO;
> +}
> +static inline void xfs_unmount_zones(struct xfs_mount *mp)
> +{
> +}
> +#endif /* CONFIG_XFS_RT */
> +
> +#endif /* _XFS_ZONE_ALLOC_H */
> diff --git a/fs/xfs/xfs_zone_priv.h b/fs/xfs/xfs_zone_priv.h
> new file mode 100644
> index 000000000000..23d2fd6088ae
> --- /dev/null
> +++ b/fs/xfs/xfs_zone_priv.h
> @@ -0,0 +1,89 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _XFS_ZONE_PRIV_H
> +#define _XFS_ZONE_PRIV_H
> +
> +struct xfs_open_zone {
> + /*
> + * Entry in the open zone list and refcount. Protected by
> + * zi_open_zones_lock in struct xfs_zone_info.
> + */
> + struct list_head oz_entry;
> + atomic_t oz_ref;
> +
> + /*
> + * oz_write_pointer is the write pointer at which space is handed out
> + * for conventional zones, or simple the count of blocks handed out
> + * so far for sequential write required zones and is protected by
> + * oz_alloc_lock/
> + */
> + spinlock_t oz_alloc_lock;
> + xfs_rgblock_t oz_write_pointer;
> +
> + /*
> + * oz_written is the number of blocks for which we've received a
> + * write completion. oz_written must always be <= oz_write_pointer
> + * and is protected by the ILOCK of the rmap inode.
> + */
> + xfs_rgblock_t oz_written;
> +
> + /*
> + * Is this open zone used for garbage collection? There can only be a
> + * single open GC zone, which is pointed to by zi_open_gc_zone in
> + * struct xfs_zone_info. Constant over the life time of an open zone.
> + */
> + bool oz_is_gc;
> +
> + /*
> + * Pointer to the RT groups structure for this open zone. Constant over
> + * the life time of an open zone.
> + */
> + struct xfs_rtgroup *oz_rtg;
> +};
> +
> +struct xfs_zone_info {
> + /*
> + * List of pending space reservations:
> + */
> + spinlock_t zi_reservation_lock;
> + struct list_head zi_reclaim_reservations;
> +
> + /*
> + * List and number of open zones:
> + */
> + spinlock_t zi_open_zones_lock;
> + struct list_head zi_open_zones;
> + unsigned int zi_nr_open_zones;
> +
> + /*
> + * Free zone search cursor and number of free zones:
> + */
> + unsigned long zi_free_zone_cursor;
> + atomic_t zi_nr_free_zones;
> +
> + /*
> + * Wait queue to wait for free zones or open zone resources to become
> + * available:
> + */
> + wait_queue_head_t zi_zone_wait;
> +
> + /*
> + * Pointer to the GC thread, and the current open zone used by GC
> + * (if any).
> + *
> + * zi_open_gc_zone is mostly private to the GC thread, but can be read
> + * for debugging from other threads, in which case zi_open_zones_lock
> + * must be taken to access it.
> + */
> + struct task_struct *zi_gc_thread;
> + struct xfs_open_zone *zi_open_gc_zone;
> +
> + /*
> + * List of zones that need a reset:
> + */
> + spinlock_t zi_reset_list_lock;
> + struct xfs_group *zi_reset_list;
> +};
> +
> +struct xfs_open_zone *xfs_open_zone(struct xfs_mount *mp, bool is_gc);
> +
> +#endif /* _XFS_ZONE_PRIV_H */
> --
> 2.45.2
>
>