diff options
Diffstat (limited to 'fs/xfs/xfs_mount.c')
| -rw-r--r-- | fs/xfs/xfs_mount.c | 918 |
1 files changed, 108 insertions, 810 deletions
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c index 4fa80e63eea2..2ce7ee3b4ec1 100644 --- a/fs/xfs/xfs_mount.c +++ b/fs/xfs/xfs_mount.c @@ -43,18 +43,6 @@ #include "xfs_sysfs.h" -#ifdef HAVE_PERCPU_SB -STATIC void xfs_icsb_balance_counter(xfs_mount_t *, xfs_sb_field_t, - int); -STATIC void xfs_icsb_balance_counter_locked(xfs_mount_t *, xfs_sb_field_t, - int); -STATIC void xfs_icsb_disable_counter(xfs_mount_t *, xfs_sb_field_t); -#else - -#define xfs_icsb_balance_counter(mp, a, b) do { } while (0) -#define xfs_icsb_balance_counter_locked(mp, a, b) do { } while (0) -#endif - static DEFINE_MUTEX(xfs_uuid_table_mutex); static int xfs_uuid_table_size; static uuid_t *xfs_uuid_table; @@ -347,8 +335,7 @@ reread: goto reread; } - /* Initialize per-cpu counters */ - xfs_icsb_reinit_counters(mp); + xfs_reinit_percpu_counters(mp); /* no need to be quiet anymore, so reset the buf ops */ bp->b_ops = &xfs_sb_buf_ops; @@ -1087,8 +1074,6 @@ xfs_log_sbcount(xfs_mount_t *mp) if (!xfs_fs_writable(mp, SB_FREEZE_COMPLETE)) return 0; - xfs_icsb_sync_counters(mp, 0); - /* * we don't need to do this if we are updating the superblock * counters on every modification. @@ -1099,253 +1084,136 @@ xfs_log_sbcount(xfs_mount_t *mp) return xfs_sync_sb(mp, true); } -/* - * 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 - * switch on the field indicated and apply the delta to that field. - * Fields are not allowed to dip below zero, so if the delta would - * do this do not apply it and return EINVAL. - * - * The m_sb_lock must be held when this routine is called. - */ -STATIC int -xfs_mod_incore_sb_unlocked( - xfs_mount_t *mp, - xfs_sb_field_t field, - int64_t delta, - int rsvd) +int +xfs_mod_icount( + struct xfs_mount *mp, + int64_t delta) { - int scounter; /* short counter for 32 bit fields */ - long long lcounter; /* long counter for 64 bit fields */ - long long res_used, rem; - - /* - * With the in-core superblock spin lock held, switch - * on the indicated field. Apply the delta to the - * proper field. If the fields value would dip below - * 0, then do not apply the delta and return EINVAL. - */ - switch (field) { - case XFS_SBS_ICOUNT: - lcounter = (long long)mp->m_sb.sb_icount; - lcounter += delta; - if (lcounter < 0) { - ASSERT(0); - return -EINVAL; - } - mp->m_sb.sb_icount = lcounter; - return 0; - 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; - case XFS_SBS_FDBLOCKS: - lcounter = (long long) - mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp); - res_used = (long long)(mp->m_resblks - mp->m_resblks_avail); - - if (delta > 0) { /* Putting blocks back */ - if (res_used > delta) { - mp->m_resblks_avail += delta; - } else { - rem = delta - res_used; - mp->m_resblks_avail = mp->m_resblks; - lcounter += rem; - } - } else { /* Taking blocks away */ - lcounter += delta; - if (lcounter >= 0) { - mp->m_sb.sb_fdblocks = lcounter + - XFS_ALLOC_SET_ASIDE(mp); - return 0; - } - - /* - * We are out of blocks, use any available reserved - * blocks if were allowed to. - */ - if (!rsvd) - return -ENOSPC; - - lcounter = (long long)mp->m_resblks_avail + delta; - if (lcounter >= 0) { - mp->m_resblks_avail = lcounter; - return 0; - } - printk_once(KERN_WARNING - "Filesystem \"%s\": reserve blocks depleted! " - "Consider increasing reserve pool size.", - mp->m_fsname); - return -ENOSPC; - } - - mp->m_sb.sb_fdblocks = lcounter + XFS_ALLOC_SET_ASIDE(mp); - return 0; - case XFS_SBS_FREXTENTS: - lcounter = (long long)mp->m_sb.sb_frextents; - lcounter += delta; - if (lcounter < 0) { - return -ENOSPC; - } - mp->m_sb.sb_frextents = lcounter; - return 0; - case XFS_SBS_DBLOCKS: - lcounter = (long long)mp->m_sb.sb_dblocks; - lcounter += delta; - if (lcounter < 0) { - ASSERT(0); - return -EINVAL; - } - mp->m_sb.sb_dblocks = lcounter; - return 0; - case XFS_SBS_AGCOUNT: - scounter = mp->m_sb.sb_agcount; - scounter += delta; - if (scounter < 0) { - ASSERT(0); - return -EINVAL; - } - mp->m_sb.sb_agcount = scounter; - return 0; - case XFS_SBS_IMAX_PCT: - scounter = mp->m_sb.sb_imax_pct; - scounter += delta; - if (scounter < 0) { - ASSERT(0); - return -EINVAL; - } - mp->m_sb.sb_imax_pct = scounter; - return 0; - case XFS_SBS_REXTSIZE: - scounter = mp->m_sb.sb_rextsize; - scounter += delta; - if (scounter < 0) { - ASSERT(0); - return -EINVAL; - } - mp->m_sb.sb_rextsize = scounter; - return 0; - case XFS_SBS_RBMBLOCKS: - scounter = mp->m_sb.sb_rbmblocks; - scounter += delta; - if (scounter < 0) { - ASSERT(0); - return -EINVAL; - } - mp->m_sb.sb_rbmblocks = scounter; - return 0; - case XFS_SBS_RBLOCKS: - lcounter = (long long)mp->m_sb.sb_rblocks; - lcounter += delta; - if (lcounter < 0) { - ASSERT(0); - return -EINVAL; - } - mp->m_sb.sb_rblocks = lcounter; - return 0; - case XFS_SBS_REXTENTS: - lcounter = (long long)mp->m_sb.sb_rextents; - lcounter += delta; - if (lcounter < 0) { - ASSERT(0); - return -EINVAL; - } - mp->m_sb.sb_rextents = lcounter; - return 0; - case XFS_SBS_REXTSLOG: - scounter = mp->m_sb.sb_rextslog; - scounter += delta; - if (scounter < 0) { - ASSERT(0); - return -EINVAL; - } - mp->m_sb.sb_rextslog = scounter; - return 0; - default: + /* deltas are +/-64, hence the large batch size of 128. */ + __percpu_counter_add(&mp->m_icount, delta, 128); + if (percpu_counter_compare(&mp->m_icount, 0) < 0) { ASSERT(0); + percpu_counter_add(&mp->m_icount, -delta); return -EINVAL; } + return 0; } -/* - * xfs_mod_incore_sb() is used to change a field in the in-core - * superblock structure by the specified delta. This modification - * is protected by the m_sb_lock. Just use the xfs_mod_incore_sb_unlocked() - * routine to do the work. - */ int -xfs_mod_incore_sb( +xfs_mod_ifree( struct xfs_mount *mp, - xfs_sb_field_t field, - int64_t delta, - int rsvd) + int64_t delta) { - int status; - -#ifdef HAVE_PERCPU_SB - ASSERT(field < XFS_SBS_ICOUNT || field > XFS_SBS_FDBLOCKS); -#endif - spin_lock(&mp->m_sb_lock); - status = xfs_mod_incore_sb_unlocked(mp, field, delta, rsvd); - spin_unlock(&mp->m_sb_lock); - - return status; + 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; } -/* - * Change more than one field in the in-core superblock structure at a time. - * - * The fields and changes to those fields are specified in the array of - * xfs_mod_sb structures passed in. Either all of the specified deltas - * will be applied or none of them will. If any modified field dips below 0, - * then all modifications will be backed out and EINVAL will be returned. - * - * Note that this function may not be used for the superblock values that - * are tracked with the in-memory per-cpu counters - a direct call to - * xfs_icsb_modify_counters is required for these. - */ int -xfs_mod_incore_sb_batch( +xfs_mod_fdblocks( struct xfs_mount *mp, - xfs_mod_sb_t *msb, - uint nmsb, - int rsvd) + int64_t delta, + bool rsvd) { - xfs_mod_sb_t *msbp; - int error = 0; + int64_t lcounter; + long long res_used; + s32 batch; + + if (delta > 0) { + /* + * If the reserve pool is depleted, put blocks back into it + * first. Most of the time the pool is full. + */ + if (likely(mp->m_resblks == mp->m_resblks_avail)) { + percpu_counter_add(&mp->m_fdblocks, delta); + return 0; + } + + spin_lock(&mp->m_sb_lock); + res_used = (long long)(mp->m_resblks - mp->m_resblks_avail); + + if (res_used > delta) { + mp->m_resblks_avail += delta; + } else { + delta -= res_used; + mp->m_resblks_avail = mp->m_resblks; + percpu_counter_add(&mp->m_fdblocks, delta); + } + spin_unlock(&mp->m_sb_lock); + return 0; + } /* - * Loop through the array of mod structures and apply each individually. - * If any fail, then back out all those which have already been applied. - * Do all of this within the scope of the m_sb_lock so that all of the - * changes will be atomic. + * Taking blocks away, need to be more accurate the closer we + * are to zero. + * + * batch size is set to a maximum of 1024 blocks - if we are + * allocating of freeing extents larger than this then we aren't + * going to be hammering the counter lock so a lock per update + * is not a problem. + * + * If the counter has a value of less than 2 * max batch size, + * then make everything serialise as we are real close to + * ENOSPC. + */ +#define __BATCH 1024 + if (percpu_counter_compare(&mp->m_fdblocks, 2 * __BATCH) < 0) + batch = 1; + else + batch = __BATCH; +#undef __BATCH + + __percpu_counter_add(&mp->m_fdblocks, delta, batch); + if (percpu_counter_compare(&mp->m_fdblocks, + XFS_ALLOC_SET_ASIDE(mp)) >= 0) { + /* we had space! */ + return 0; + } + + /* + * lock up the sb for dipping into reserves before releasing the space + * that took us to ENOSPC. */ spin_lock(&mp->m_sb_lock); - for (msbp = msb; msbp < (msb + nmsb); msbp++) { - ASSERT(msbp->msb_field < XFS_SBS_ICOUNT || - msbp->msb_field > XFS_SBS_FDBLOCKS); + percpu_counter_add(&mp->m_fdblocks, -delta); + if (!rsvd) + goto fdblocks_enospc; - error = xfs_mod_incore_sb_unlocked(mp, msbp->msb_field, - msbp->msb_delta, rsvd); - if (error) - goto unwind; + lcounter = (long long)mp->m_resblks_avail + delta; + if (lcounter >= 0) { + mp->m_resblks_avail = lcounter; + spin_unlock(&mp->m_sb_lock); + return 0; } + printk_once(KERN_WARNING + "Filesystem \"%s\": reserve blocks depleted! " + "Consider increasing reserve pool size.", + mp->m_fsname); +fdblocks_enospc: spin_unlock(&mp->m_sb_lock); - return 0; + return -ENOSPC; +} -unwind: - while (--msbp >= msb) { - error = xfs_mod_incore_sb_unlocked(mp, msbp->msb_field, - -msbp->msb_delta, rsvd); - ASSERT(error == 0); - } +int +xfs_mod_frextents( + struct xfs_mount *mp, + int64_t delta) +{ + int64_t lcounter; + int ret = 0; + + spin_lock(&mp->m_sb_lock); + lcounter = mp->m_sb.sb_frextents + delta; + if (lcounter < 0) + ret = -ENOSPC; + else + mp->m_sb.sb_frextents = lcounter; spin_unlock(&mp->m_sb_lock); - return error; + return ret; } /* @@ -1407,573 +1275,3 @@ xfs_dev_is_read_only( } return 0; } - -#ifdef HAVE_PERCPU_SB -/* - * Per-cpu incore superblock counters - * - * Simple concept, difficult implementation - * - * Basically, replace the incore superblock counters with a distributed per cpu - * counter for contended fields (e.g. free block count). - * - * Difficulties arise in that the incore sb is used for ENOSPC checking, and - * hence needs to be accurately read when we are running low on space. Hence - * there is a method to enable and disable the per-cpu counters based on how - * much "stuff" is available in them. - * - * Basically, a counter is enabled if there is enough free resource to justify - * running a per-cpu fast-path. If the per-cpu counter runs out (i.e. a local - * ENOSPC), then we disable the counters to synchronise all callers and - * re-distribute the available resources. - * - * If, once we redistributed the available resources, we still get a failure, - * we disable the per-cpu counter and go through the slow path. - * - * The slow path is the current xfs_mod_incore_sb() function. This means that - * when we disable a per-cpu counter, we need to drain its resources back to - * the global superblock. We do this after disabling the counter to prevent - * more threads from queueing up on the counter. - * - * Essentially, this means that we still need a lock in the fast path to enable - * synchronisation between the global counters and the per-cpu counters. This - * is not a problem because the lock will be local to a CPU almost all the time - * and have little contention except when we get to ENOSPC conditions. - * - * Basically, this lock becomes a barrier that enables us to lock out the fast - * path while we do things like enabling and disabling counters and - * synchronising the counters. - * - * Locking rules: - * - * 1. m_sb_lock before picking up per-cpu locks - * 2. per-cpu locks always picked up via for_each_online_cpu() order - * 3. accurate counter sync requires m_sb_lock + per cpu locks - * 4. modifying per-cpu counters requires holding per-cpu lock - * 5. modifying global counters requires holding m_sb_lock - * 6. enabling or disabling a counter requires holding the m_sb_lock - * and _none_ of the per-cpu locks. - * - * Disabled counters are only ever re-enabled by a balance operation - * that results in more free resources per CPU than a given threshold. - * To ensure counters don't remain disabled, they are rebalanced when - * the global resource goes above a higher threshold (i.e. some hysteresis - * is present to prevent thrashing). - */ - -#ifdef CONFIG_HOTPLUG_CPU -/* - * hot-plug CPU notifier support. - * - * We need a notifier per filesystem as we need to be able to identify - * the filesystem to balance the counters out. This is achieved by - * having a notifier block embedded in the xfs_mount_t and doing pointer - * magic to get the mount pointer from the notifier block address. - */ -STATIC int -xfs_icsb_cpu_notify( - struct notifier_block *nfb, - unsigned long action, - void *hcpu) -{ - xfs_icsb_cnts_t *cntp; - xfs_mount_t *mp; - - mp = (xfs_mount_t *)container_of(nfb, xfs_mount_t, m_icsb_notifier); - cntp = (xfs_icsb_cnts_t *) - per_cpu_ptr(mp->m_sb_cnts, (unsigned long)hcpu); - switch (action) { - case CPU_UP_PREPARE: - case CPU_UP_PREPARE_FROZEN: - /* Easy Case - initialize the area and locks, and - * then rebalance when online does everything else for us. */ - memset(cntp, 0, sizeof(xfs_icsb_cnts_t)); - break; - case CPU_ONLINE: - case CPU_ONLINE_FROZEN: - xfs_icsb_lock(mp); - xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, 0); - xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, 0); - xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, 0); - xfs_icsb_unlock(mp); - break; - case CPU_DEAD: - case CPU_DEAD_FROZEN: - /* Disable all the counters, then fold the dead cpu's - * count into the total on the global superblock and - * re-enable the counters. */ - xfs_icsb_lock(mp); - spin_lock(&mp->m_sb_lock); - xfs_icsb_disable_counter(mp, XFS_SBS_ICOUNT); - xfs_icsb_disable_counter(mp, XFS_SBS_IFREE); - xfs_icsb_disable_counter(mp, XFS_SBS_FDBLOCKS); - - mp->m_sb.sb_icount += cntp->icsb_icount; - 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_ICOUNT, 0); - 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); - break; - } - - return NOTIFY_OK; -} -#endif /* CONFIG_HOTPLUG_CPU */ - -int -xfs_icsb_init_counters( - xfs_mount_t *mp) -{ - xfs_icsb_cnts_t *cntp; - int i; - - mp->m_sb_cnts = alloc_percpu(xfs_icsb_cnts_t); - if (mp->m_sb_cnts == NULL) - return -ENOMEM; - - for_each_online_cpu(i) { - cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i); - memset(cntp, 0, sizeof(xfs_icsb_cnts_t)); - } - - mutex_init(&mp->m_icsb_mutex); - - /* - * start with all counters disabled so that the - * initial balance kicks us off correctly - */ - mp->m_icsb_counters = -1; - -#ifdef CONFIG_HOTPLUG_CPU - mp->m_icsb_notifier.notifier_call = xfs_icsb_cpu_notify; - mp->m_icsb_notifier.priority = 0; - register_hotcpu_notifier(&mp->m_icsb_notifier); -#endif /* CONFIG_HOTPLUG_CPU */ - - return 0; -} - -void -xfs_icsb_reinit_counters( - xfs_mount_t *mp) -{ - xfs_icsb_lock(mp); - /* - * start with all counters disabled so that the - * initial balance kicks us off correctly - */ - mp->m_icsb_counters = -1; - xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, 0); - xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, 0); - xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, 0); - xfs_icsb_unlock(mp); -} - -void -xfs_icsb_destroy_counters( - xfs_mount_t *mp) -{ - if (mp->m_sb_cnts) { - unregister_hotcpu_notifier(&mp->m_icsb_notifier); - free_percpu(mp->m_sb_cnts); - } - mutex_destroy(&mp->m_icsb_mutex); -} - -STATIC void -xfs_icsb_lock_cntr( - xfs_icsb_cnts_t *icsbp) -{ - while (test_and_set_bit(XFS_ICSB_FLAG_LOCK, &icsbp->icsb_flags)) { - ndelay(1000); - } -} - -STATIC void -xfs_icsb_unlock_cntr( - xfs_icsb_cnts_t *icsbp) -{ - clear_bit(XFS_ICSB_FLAG_LOCK, &icsbp->icsb_flags); -} - - -STATIC void -xfs_icsb_lock_all_counters( - xfs_mount_t *mp) -{ - xfs_icsb_cnts_t *cntp; - int i; - - for_each_online_cpu(i) { - cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i); - xfs_icsb_lock_cntr(cntp); - } -} - -STATIC void -xfs_icsb_unlock_all_counters( - xfs_mount_t *mp) -{ - xfs_icsb_cnts_t *cntp; - int i; - - for_each_online_cpu(i) { - cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i); - xfs_icsb_unlock_cntr(cntp); - } -} - -STATIC void -xfs_icsb_count( - xfs_mount_t *mp, - xfs_icsb_cnts_t *cnt, - int flags) -{ - xfs_icsb_cnts_t *cntp; - int i; - - memset(cnt, 0, sizeof(xfs_icsb_cnts_t)); - - if (!(flags & XFS_ICSB_LAZY_COUNT)) - xfs_icsb_lock_all_counters(mp); - - for_each_online_cpu(i) { - cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i); - cnt->icsb_icount += cntp->icsb_icount; - cnt->icsb_ifree += cntp->icsb_ifree; - cnt->icsb_fdblocks += cntp->icsb_fdblocks; - } - - if (!(flags & XFS_ICSB_LAZY_COUNT)) - xfs_icsb_unlock_all_counters(mp); -} - -STATIC int -xfs_icsb_counter_disabled( - xfs_mount_t *mp, - xfs_sb_field_t field) -{ - ASSERT((field >= XFS_SBS_ICOUNT) && (field <= XFS_SBS_FDBLOCKS)); - return test_bit(field, &mp->m_icsb_counters); -} - -STATIC void -xfs_icsb_disable_counter( - xfs_mount_t *mp, - xfs_sb_field_t field) -{ - xfs_icsb_cnts_t cnt; - - ASSERT((field >= XFS_SBS_ICOUNT) && (field <= XFS_SBS_FDBLOCKS)); - - /* - * If we are already disabled, then there is nothing to do - * here. We check before locking all the counters to avoid - * the expensive lock operation when being called in the - * slow path and the counter is already disabled. This is - * safe because the only time we set or clear this state is under - * the m_icsb_mutex. - */ - if (xfs_icsb_counter_disabled(mp, field)) - return; - - xfs_icsb_lock_all_counters(mp); - if (!test_and_set_bit(field, &mp->m_icsb_counters)) { - /* drain back to superblock */ - - xfs_icsb_count(mp, &cnt, XFS_ICSB_LAZY_COUNT); - switch(field) { - case XFS_SBS_ICOUNT: - mp->m_sb.sb_icount = cnt.icsb_icount; - break; - 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; - default: - BUG(); - } - } - - xfs_icsb_unlock_all_counters(mp); -} - -STATIC void -xfs_icsb_enable_counter( - xfs_mount_t *mp, - xfs_sb_field_t field, - uint64_t count, - uint64_t resid) -{ - xfs_icsb_cnts_t *cntp; - int i; - - ASSERT((field >= XFS_SBS_ICOUNT) && (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_ICOUNT: - cntp->icsb_icount = count + resid; - break; - case XFS_SBS_IFREE: - cntp->icsb_ifree = count + resid; - break; - case XFS_SBS_FDBLOCKS: - cntp->icsb_fdblocks = count + resid; - break; - default: - BUG(); - break; - } - resid = 0; - } - clear_bit(field, &mp->m_icsb_counters); - xfs_icsb_unlock_all_counters(mp); -} - -void -xfs_icsb_sync_counters_locked( - xfs_mount_t *mp, - int flags) -{ - xfs_icsb_cnts_t cnt; - - xfs_icsb_count(mp, &cnt, flags); - - if (!xfs_icsb_counter_disabled(mp, XFS_SBS_ICOUNT)) - mp->m_sb.sb_icount = cnt.icsb_icount; - 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; -} - -/* - * Accurate update of per-cpu counters to incore superblock - */ -void -xfs_icsb_sync_counters( - xfs_mount_t *mp, - int flags) -{ - spin_lock(&mp->m_sb_lock); - xfs_icsb_sync_counters_locked(mp, flags); - spin_unlock(&mp->m_sb_lock); -} - -/* - * Balance and enable/disable counters as necessary. - * - * Thresholds for re-enabling counters are somewhat magic. inode counts are - * chosen to be the same number as single on disk allocation chunk per CPU, and - * free blocks is something far enough zero that we aren't going thrash when we - * get near ENOSPC. We also need to supply a minimum we require per cpu to - * prevent looping endlessly when xfs_alloc_space asks for more than will - * be distributed to a single CPU but each CPU has enough blocks to be - * reenabled. - * - * Note that we can be called when counters are already disabled. - * xfs_icsb_disable_counter() optimises the counter locking in this case to - * prevent locking every per-cpu counter needlessly. - */ - -#define XFS_ICSB_INO_CNTR_REENABLE (uint64_t)64 -#define XFS_ICSB_FDBLK_CNTR_REENABLE(mp) \ - (uint64_t)(512 + XFS_ALLOC_SET_ASIDE(mp)) -STATIC void -xfs_icsb_balance_counter_locked( - xfs_mount_t *mp, - xfs_sb_field_t field, - int min_per_cpu) -{ - uint64_t count, resid; - int weight = num_online_cpus(); - uint64_t min = (uint64_t)min_per_cpu; - - /* disable counter and sync counter */ - xfs_icsb_disable_counter(mp, field); - - /* update counters - first CPU gets residual*/ - switch (field) { - case XFS_SBS_ICOUNT: - count = mp->m_sb.sb_icount; - resid = do_div(count, weight); - if (count < max(min, XFS_ICSB_INO_CNTR_REENABLE)) - return; - break; - 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); - if (count < max(min, XFS_ICSB_FDBLK_CNTR_REENABLE(mp))) - return; - break; - default: - BUG(); - count = resid = 0; /* quiet, gcc */ - break; - } - - xfs_icsb_enable_counter(mp, field, count, resid); -} - -STATIC void -xfs_icsb_balance_counter( - xfs_mount_t *mp, - xfs_sb_field_t fields, - int min_per_cpu) -{ - spin_lock(&mp->m_sb_lock); - xfs_icsb_balance_counter_locked(mp, fields, min_per_cpu); - spin_unlock(&mp->m_sb_lock); -} - -int -xfs_icsb_modify_counters( - xfs_mount_t *mp, - xfs_sb_field_t field, - int64_t delta, - int rsvd) -{ - xfs_icsb_cnts_t *icsbp; - long long lcounter; /* long counter for 64 bit fields */ - int ret = 0; - - might_sleep(); -again: - preempt_disable(); - icsbp = this_cpu_ptr(mp->m_sb_cnts); - - /* - * if the counter is disabled, go to slow path - */ - if (unlikely(xfs_icsb_counter_disabled(mp, field))) - goto slow_path; - xfs_icsb_lock_cntr(icsbp); - if (unlikely(xfs_icsb_counter_disabled(mp, field))) { - xfs_icsb_unlock_cntr(icsbp); - goto slow_path; - } - - switch (field) { - case XFS_SBS_ICOUNT: - lcounter = icsbp->icsb_icount; - lcounter += delta; - if (unlikely(lcounter < 0)) - goto balance_counter; - icsbp->icsb_icount = lcounter; - break; - - 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); - - lcounter = icsbp->icsb_fdblocks - XFS_ALLOC_SET_ASIDE(mp); - lcounter += delta; - if (unlikely(lcounter < 0)) - goto balance_counter; - icsbp->icsb_fdblocks = lcounter + XFS_ALLOC_SET_ASIDE(mp); - break; - default: - BUG(); - break; - } - xfs_icsb_unlock_cntr(icsbp); - preempt_enable(); - return 0; - -slow_path: - preempt_enable(); - - /* - * serialise with a mutex so we don't burn lots of cpu on - * the superblock lock. We still need to hold the superblock - * lock, however, when we modify the global structures. - */ - xfs_icsb_lock(mp); - - /* - * Now running atomically. - * - * If the counter is enabled, someone has beaten us to rebalancing. - * Drop the lock and try again in the fast path.... - */ - if (!(xfs_icsb_counter_disabled(mp, field))) { - xfs_icsb_unlock(mp); - goto again; - } - - /* - * The counter is currently disabled. Because we are - * running atomically here, we know a rebalance cannot - * be in progress. Hence we can go straight to operating - * on the global superblock. We do not call xfs_mod_incore_sb() - * here even though we need to get the m_sb_lock. Doing so - * will cause us to re-enter this function and deadlock. - * Hence we get the m_sb_lock ourselves and then call - * xfs_mod_incore_sb_unlocked() as the unlocked path operates - * directly on the global counters. - */ - spin_lock(&mp->m_sb_lock); - ret = xfs_mod_incore_sb_unlocked(mp, field, delta, rsvd); - spin_unlock(&mp->m_sb_lock); - - /* - * Now that we've modified the global superblock, we - * may be able to re-enable the distributed counters - * (e.g. lots of space just got freed). After that - * we are done. - */ - if (ret != -ENOSPC) - xfs_icsb_balance_counter(mp, field, 0); - xfs_icsb_unlock(mp); - return ret; - -balance_counter: - xfs_icsb_unlock_cntr(icsbp); - preempt_enable(); - - /* - * We may have multiple threads here if multiple per-cpu - * counters run dry at the same time. This will mean we can - * do more balances than strictly necessary but it is not - * the common slowpath case. - */ - xfs_icsb_lock(mp); - - /* - * running atomically. - * - * This will leave the counter in the correct state for future - * accesses. After the rebalance, we simply try again and our retry - * will either succeed through the fast path or slow path without - * another balance operation being required. - */ - xfs_icsb_balance_counter(mp, field, delta); - xfs_icsb_unlock(mp); - goto again; -} - -#endif |