Re: [PATCH 2/7] xfs: use generic percpu counters for free inode counter

Brian Foster
2015-02-05T14:10:14Z

On Thu, Feb 05, 2015 at 07:54:04AM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> XFS has hand-rolled per-cpu counters for the superblock since before
> there was any generic implementation. The free inode counter is not
> used for any limit enforcement - the per-AG free inode counters are
> used during allocation to determine if there are inode available for
> allocation.
>
> Hence we don't need any of the complexity of the hand-rolled
> counters and we can simply replace them with generic per-cpu
> counters similar to the inode counter.
>
> This version introduces a xfs_mod_ifree() helper function from
> Christoph Hellwig.
>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

> fs/xfs/libxfs/xfs_sb.c | 1 +
> fs/xfs/xfs_fsops.c | 2 +-
> fs/xfs/xfs_mount.c | 76 ++++++++++++++++++++++----------------------------
> fs/xfs/xfs_mount.h | 2 ++
> fs/xfs/xfs_super.c | 4 ++-
> fs/xfs/xfs_trans.c | 5 ++--
> 6 files changed, 42 insertions(+), 48 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
> index 017cb2f..b66aeab 100644
> --- a/fs/xfs/libxfs/xfs_sb.c
> +++ b/fs/xfs/libxfs/xfs_sb.c
> @@ -772,6 +772,7 @@ xfs_log_sb(
> struct xfs_buf *bp = xfs_trans_getsb(tp, mp, 0);
>
> mp->m_sb.sb_icount = percpu_counter_sum(&mp->m_icount);
> + mp->m_sb.sb_ifree = percpu_counter_sum(&mp->m_ifree);
>
> xfs_sb_to_disk(XFS_BUF_TO_SBP(bp), &mp->m_sb);
> xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SB_BUF);
> diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
> index e1470f2..fa74d03 100644
> --- a/fs/xfs/xfs_fsops.c
> +++ b/fs/xfs/xfs_fsops.c
> @@ -632,11 +632,11 @@ xfs_fs_counts(
> {
> xfs_icsb_sync_counters(mp, XFS_ICSB_LAZY_COUNT);
> cnt->allocino = percpu_counter_read_positive(&mp->m_icount);
> + cnt->freeino = percpu_counter_read_positive(&mp->m_ifree);
>
> spin_lock(&mp->m_sb_lock);
> cnt->freedata = mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
> cnt->freertx = mp->m_sb.sb_frextents;
> - cnt->freeino = mp->m_sb.sb_ifree;
> spin_unlock(&mp->m_sb_lock);
> return 0;
> }
> diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
> index 702ea6a..650e8f1 100644
> --- a/fs/xfs/xfs_mount.c
> +++ b/fs/xfs/xfs_mount.c
> @@ -1114,6 +1114,20 @@ xfs_mod_icount(
> return 0;
> }
>
> +
> +int
> +xfs_mod_ifree(
> + struct xfs_mount *mp,
> + int64_t delta)
> +{
> + percpu_counter_add(&mp->m_ifree, delta);
> + if (percpu_counter_compare(&mp->m_ifree, 0) < 0) {
> + ASSERT(0);
> + percpu_counter_add(&mp->m_ifree, -delta);
> + return -EINVAL;
> + }
> + return 0;
> +}
> /*
> * xfs_mod_incore_sb_unlocked() is a utility routine commonly used to apply
> * a delta to a specified field in the in-core superblock. Simply
> @@ -1142,17 +1156,9 @@ xfs_mod_incore_sb_unlocked(
> */
> switch (field) {
> case XFS_SBS_ICOUNT:
> - ASSERT(0);
> - return -ENOSPC;
> case XFS_SBS_IFREE:
> - lcounter = (long long)mp->m_sb.sb_ifree;
> - lcounter += delta;
> - if (lcounter < 0) {
> - ASSERT(0);
> - return -EINVAL;
> - }
> - mp->m_sb.sb_ifree = lcounter;
> - return 0;
> + ASSERT(0);
> + return -EINVAL;
> case XFS_SBS_FDBLOCKS:
> lcounter = (long long)
> mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
> @@ -1502,7 +1508,6 @@ xfs_icsb_cpu_notify(
> case CPU_ONLINE:
> case CPU_ONLINE_FROZEN:
> xfs_icsb_lock(mp);
> - xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, 0);
> xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, 0);
> xfs_icsb_unlock(mp);
> break;
> @@ -1513,15 +1518,12 @@ xfs_icsb_cpu_notify(
> * re-enable the counters. */
> xfs_icsb_lock(mp);
> spin_lock(&mp->m_sb_lock);
> - xfs_icsb_disable_counter(mp, XFS_SBS_IFREE);
> xfs_icsb_disable_counter(mp, XFS_SBS_FDBLOCKS);
>
> - mp->m_sb.sb_ifree += cntp->icsb_ifree;
> mp->m_sb.sb_fdblocks += cntp->icsb_fdblocks;
>
> memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
>
> - xfs_icsb_balance_counter_locked(mp, XFS_SBS_IFREE, 0);
> xfs_icsb_balance_counter_locked(mp, XFS_SBS_FDBLOCKS, 0);
> spin_unlock(&mp->m_sb_lock);
> xfs_icsb_unlock(mp);
> @@ -1544,10 +1546,14 @@ xfs_icsb_init_counters(
> if (error)
> return error;
>
> + error = percpu_counter_init(&mp->m_ifree, 0, GFP_KERNEL);
> + if (error)
> + goto free_icount;
> +
> mp->m_sb_cnts = alloc_percpu(xfs_icsb_cnts_t);
> if (!mp->m_sb_cnts) {
> - percpu_counter_destroy(&mp->m_icount);
> - return -ENOMEM;
> + error = -ENOMEM;
> + goto free_ifree;
> }
>
> for_each_online_cpu(i) {
> @@ -1570,6 +1576,12 @@ xfs_icsb_init_counters(
> #endif /* CONFIG_HOTPLUG_CPU */
>
> return 0;
> +
> +free_ifree:
> + percpu_counter_destroy(&mp->m_ifree);
> +free_icount:
> + percpu_counter_destroy(&mp->m_icount);
> + return error;
> }
>
> void
> @@ -1577,6 +1589,7 @@ xfs_icsb_reinit_counters(
> xfs_mount_t *mp)
> {
> percpu_counter_set(&mp->m_icount, mp->m_sb.sb_icount);
> + percpu_counter_set(&mp->m_ifree, mp->m_sb.sb_ifree);
>
> xfs_icsb_lock(mp);
> /*
> @@ -1584,7 +1597,6 @@ xfs_icsb_reinit_counters(
> * initial balance kicks us off correctly
> */
> mp->m_icsb_counters = -1;
> - xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, 0);
> xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, 0);
> xfs_icsb_unlock(mp);
> }
> @@ -1599,6 +1611,7 @@ xfs_icsb_destroy_counters(
> }
>
> percpu_counter_destroy(&mp->m_icount);
> + percpu_counter_destroy(&mp->m_ifree);
>
> mutex_destroy(&mp->m_icsb_mutex);
> }
> @@ -1662,7 +1675,6 @@ xfs_icsb_count(
>
> for_each_online_cpu(i) {
> cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
> - cnt->icsb_ifree += cntp->icsb_ifree;
> cnt->icsb_fdblocks += cntp->icsb_fdblocks;
> }
>
> @@ -1675,7 +1687,7 @@ xfs_icsb_counter_disabled(
> xfs_mount_t *mp,
> xfs_sb_field_t field)
> {
> - ASSERT((field >= XFS_SBS_IFREE) && (field <= XFS_SBS_FDBLOCKS));
> + ASSERT(field == XFS_SBS_FDBLOCKS);
> return test_bit(field, &mp->m_icsb_counters);
> }
>
> @@ -1686,7 +1698,7 @@ xfs_icsb_disable_counter(
> {
> xfs_icsb_cnts_t cnt;
>
> - ASSERT((field >= XFS_SBS_IFREE) && (field <= XFS_SBS_FDBLOCKS));
> + ASSERT(field == XFS_SBS_FDBLOCKS);
>
> /*
> * If we are already disabled, then there is nothing to do
> @@ -1705,9 +1717,6 @@ xfs_icsb_disable_counter(
>
> xfs_icsb_count(mp, &cnt, XFS_ICSB_LAZY_COUNT);
> switch(field) {
> - case XFS_SBS_IFREE:
> - mp->m_sb.sb_ifree = cnt.icsb_ifree;
> - break;
> case XFS_SBS_FDBLOCKS:
> mp->m_sb.sb_fdblocks = cnt.icsb_fdblocks;
> break;
> @@ -1729,15 +1738,12 @@ xfs_icsb_enable_counter(
> xfs_icsb_cnts_t *cntp;
> int i;
>
> - ASSERT((field >= XFS_SBS_IFREE) && (field <= XFS_SBS_FDBLOCKS));
> + ASSERT(field == XFS_SBS_FDBLOCKS);
>
> xfs_icsb_lock_all_counters(mp);
> for_each_online_cpu(i) {
> cntp = per_cpu_ptr(mp->m_sb_cnts, i);
> switch (field) {
> - case XFS_SBS_IFREE:
> - cntp->icsb_ifree = count + resid;
> - break;
> case XFS_SBS_FDBLOCKS:
> cntp->icsb_fdblocks = count + resid;
> break;
> @@ -1760,8 +1766,6 @@ xfs_icsb_sync_counters_locked(
>
> xfs_icsb_count(mp, &cnt, flags);
>
> - if (!xfs_icsb_counter_disabled(mp, XFS_SBS_IFREE))
> - mp->m_sb.sb_ifree = cnt.icsb_ifree;
> if (!xfs_icsb_counter_disabled(mp, XFS_SBS_FDBLOCKS))
> mp->m_sb.sb_fdblocks = cnt.icsb_fdblocks;
> }
> @@ -1813,12 +1817,6 @@ xfs_icsb_balance_counter_locked(
>
> /* update counters - first CPU gets residual*/
> switch (field) {
> - case XFS_SBS_IFREE:
> - count = mp->m_sb.sb_ifree;
> - resid = do_div(count, weight);
> - if (count < max(min, XFS_ICSB_INO_CNTR_REENABLE))
> - return;
> - break;
> case XFS_SBS_FDBLOCKS:
> count = mp->m_sb.sb_fdblocks;
> resid = do_div(count, weight);
> @@ -1873,14 +1871,6 @@ again:
> }
>
> switch (field) {
> - case XFS_SBS_IFREE:
> - lcounter = icsbp->icsb_ifree;
> - lcounter += delta;
> - if (unlikely(lcounter < 0))
> - goto balance_counter;
> - icsbp->icsb_ifree = lcounter;
> - break;
> -
> case XFS_SBS_FDBLOCKS:
> BUG_ON((mp->m_resblks - mp->m_resblks_avail) != 0);
>
> diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
> index 457c6e3..0cb32ce 100644
> --- a/fs/xfs/xfs_mount.h
> +++ b/fs/xfs/xfs_mount.h
> @@ -84,6 +84,7 @@ typedef struct xfs_mount {
> struct xfs_sb m_sb; /* copy of fs superblock */
> spinlock_t m_sb_lock; /* sb counter lock */
> struct percpu_counter m_icount; /* allocated inodes counter */
> + struct percpu_counter m_ifree; /* free inodes counter */
>
> struct xfs_buf *m_sb_bp; /* buffer for superblock */
> char *m_fsname; /* filesystem name */
> @@ -380,6 +381,7 @@ extern int xfs_mod_incore_sb(xfs_mount_t *, xfs_sb_field_t, int64_t, int);
> extern int xfs_mod_incore_sb_batch(xfs_mount_t *, xfs_mod_sb_t *,
> uint, int);
> extern int xfs_mod_icount(struct xfs_mount *mp, int64_t delta);
> +extern int xfs_mod_ifree(struct xfs_mount *mp, int64_t delta);
> extern int xfs_mount_log_sb(xfs_mount_t *);
> extern struct xfs_buf *xfs_getsb(xfs_mount_t *, int);
> extern int xfs_readsb(xfs_mount_t *, int);
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index 87e169f..e06aa6b 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -1088,6 +1088,7 @@ xfs_fs_statfs(
> struct xfs_inode *ip = XFS_I(dentry->d_inode);
> __uint64_t fakeinos, id;
> __uint64_t icount;
> + __uint64_t ifree;
> xfs_extlen_t lsize;
> __int64_t ffree;
>
> @@ -1100,6 +1101,7 @@ xfs_fs_statfs(
>
> xfs_icsb_sync_counters(mp, XFS_ICSB_LAZY_COUNT);
> icount = percpu_counter_sum(&mp->m_icount);
> + ifree = percpu_counter_sum(&mp->m_ifree);
>
> spin_lock(&mp->m_sb_lock);
> statp->f_bsize = sbp->sb_blocksize;
> @@ -1115,7 +1117,7 @@ xfs_fs_statfs(
> mp->m_maxicount);
>
> /* make sure statp->f_ffree does not underflow */
> - ffree = statp->f_files - (icount - sbp->sb_ifree);
> + ffree = statp->f_files - (icount - ifree);
> statp->f_ffree = max_t(__int64_t, ffree, 0);
>
> spin_unlock(&mp->m_sb_lock);
> diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
> index 9bc742b..68680ce 100644
> --- a/fs/xfs/xfs_trans.c
> +++ b/fs/xfs/xfs_trans.c
> @@ -560,8 +560,7 @@ xfs_trans_unreserve_and_mod_sb(
> }
>
> if (ifreedelta) {
> - error = xfs_icsb_modify_counters(mp, XFS_SBS_IFREE,
> - ifreedelta, rsvd);
> + error = xfs_mod_ifree(mp, ifreedelta);
> if (error)
> goto out_undo_icount;
> }
> @@ -630,7 +629,7 @@ xfs_trans_unreserve_and_mod_sb(
>
> out_undo_ifreecount:
> if (ifreedelta)
> - xfs_icsb_modify_counters(mp, XFS_SBS_IFREE, -ifreedelta, rsvd);
> + xfs_mod_ifree(mp, -ifreedelta);
> out_undo_icount:
> if (idelta)
> xfs_mod_icount(mp, -idelta);
> --
> 2.0.0
>
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